Messerschmitt Me 262. [Archive]

panzerpete

04-14-2007, 12:58 PM

Design and development
Although often viewed as a last ditch super-weapon, the Me 262 was already being developed as project P.1065 before the start of World War II. Plans were first drawn up in April 1939, and the original design was very similar to the plane that would eventually enter service. The progression of the original design into service was delayed by a lack of funds, as many high-ranking officials thought that the war could easily be won with conventional aircraft, and therefore most of the available government funds were used for the production of other aircraft.

Swept wings had been proposed as early as 1935 by Adolf Busemann, and Willy Messerschmitt had researched the topic from 1940. In April 1941, he actually proposed to fit a 35° swept wing (Pfeilflügel II, lit. Arrow wing) to the Me 262. Though this suggestion was not implemented, he continued with the projected HG II and HG III high-speed derivatives of the Me 262 in 1944, which were designed with a 35° and 45° wing sweep respectively. The production Me 262 had a leading edge sweep of 18.5° primarily to properly position the center of lift relative to the center of mass and not for the aerodynamic benefit of increasing the critical Mach number of the wing (the sweep was too slight to achieve any significant advantage).[2] The aircraft was originally designed as a tail-dragger and the first (Me 262 V1) through fourth (-V4) prototypes flew with this configuration, but it was discovered on an early test run that the engines and wings "blanked" the stabilizers, giving almost no control on the ground. Changing to a tricycle landing gear arrangement, initially as a fixed undercarriage on the fifth prototype aircraft, then a fully retractable one on the sixth and succeeding prototypes, immediately corrected all of these problems.

The first test flights began in April 1941, but since the BMW 003 turbojets were not ready for fitting, a conventional Junkers Jumo 210 engine was mounted in the nose, driving a propeller, to test the Me 262 V1 airframe. When the BMW 003 engines were finally installed the Jumo was retained for safety which proved wise as both 003s failed during the first flight and the pilot had to land using the nose mounted engine alone.

The V3 third prototype airframe became a true "jet" when it flew on 18 July 1942 in Leipheim near Günzburg, Germany, piloted by Fritz Wendel. This was almost nine full months ahead of the British Gloster Meteor's first flight on 5 March 1943. The 003 engines, which were proving unreliable, were replaced by the newly available Junkers Jumo 004. Test flights continued over the next year but the engines continued to be unreliable. While the production of the aircraft was slowed mainly by engine trouble, an order from Adolf Hitler that the new Me 262 must also be part bomber contributed to the delays in getting the Me 262 into operation. Airframe modifications were complete by 1942, but hampered by the lack of engines, serial production did not begin until 1944. This delay in engine availability was in part due to the shortage of strategic materials, especially metals and alloys that could handle the extreme temperatures produced by the jet engine. Even when the engines were completed they had an expected operational lifetime of approximately 50 hours, however in the real world situations, most 004s lifetimes were 12 hours. A pilot familiar with the Me 262 and its engines could expect approximately 20 to 25 hours of life from the 004s. The swap out of 004s was listed as a job able to be done in three hours, but changeouts typically took eight to nine hours due to poorly made parts and inadequate training of ground crews.

panzerpete

04-14-2007, 01:00 PM

Turbojet engines have less thrust at low speed than piston engines and as a result, acceleration is relatively poor. It was more noticeable for the Me 262 as early jet engines (before the invention of afterburners) responded slowly to throttle changes. The introduction of a primitive autothrottle late in the war only helped slightly. Conversely, the higher power of jet engines at higher speeds meant the Me 262 enjoyed a much higher climb speed. Used tactically, this gave the jet fighter an even greater speed advantage in climb rate than level flight at top speed.

With one engine out, the Me 262 still flew well, with speeds of 280 to 310 mph (450 km/h to 500 km/h). However it was highly recommended to avoid attempting to land with one engine out as it was considered a hazard.[citation needed]

Operationally, the Me 262 had an endurance of 60 to 90 minutes.

[edit] Operational history

Me 262A-1a camouflaged on a German airfieldIn April 1944, Erprobungskommando 262 was formed at Lechfeld in Bavaria as a test unit to introduce the 262 into service and train a core of pilots to fly it. Major Walter Nowotny was assigned as Commander in July 1944, and the unit redesignated Kommando Nowotny. Kommando Nowotny was essentially a trials and development unit, but it holds the distinction of being the world's first jet fighter squadron. Trials continued slowly with initial operational missions against the Allies in August 1944, allegedly downing 19 Allied aircraft for six Me 262s lost, although these claims have never been verified by cross-checking with USAAF records. The RAF Museum holds no intelligence reports of RAF aircraft engaging in combat with an Me 262 in August 1944,[citation needed]although there is a report of an unarmed encounter between an Me 262 and a DH98 Mosquito.[3] Nowotny himself was shot down and killed on 8 November 1944 by 1st Lt Edward “Buddy” Haydon of the 357th Fighter Group, USAAF and Capt Ernest “Feeb” Fiebelkorn of the 20th Fighter Group, USAAF. The "Kommando" was then withdrawn for further training and a revision of combat tactics to optimise the 262's strengths.

By January 1945, Jagdgeschwader 7 (JG7) had been formed as a pure jet fighter unit, although it would be several weeks before it was operational. In the meantime a bomber unit—I Gruppe, Kampfgeschwader 54 (KG54)—had re-equipped with the Me 262 for use in a ground attack and fighter role. However, the unit lost 12 jets in action in two weeks for minimal returns.

Jagdverband 44 (JV44) was another Me 262 fighter unit formed in February, by Lieutenant General Adolf Galland, who had recently been dismissed as Inspector of Day Fighters. Galland was able to draw into the unit many of the most experienced and decorated Luftwaffe fighter pilots from other units grounded by lack of fuel.

panzerpete

04-14-2007, 01:02 PM

During March, Me 262 fighter units were thus able, for the first time, to deliver large scale attacks on Allied bomber formations. On March 18, 1945, 37 Me 262s of JG7 intercepted a force of 1,221 bombers and 632 escorting fighters. They managed to shoot down 12 bombers and one fighter for the loss of three Me 262s. Although a four-to-one ratio was exactly what the Luftwaffe would have needed to make an impact on the war, the absolute scale of their success was minor as it represented only one per cent of the attacking force. In 1943 and early 1944, the USAAF had been able to keep up offensive operations though enduring loss ratios of 5% and more, and the few available Me 262s could not inflict sufficient magnitude of losses.

Side view of a Me 262 night fighter (converted two-seated trainer)Several two-seater "B" trainer variants of the Me 262 had been adapted as night fighters, complete with on-board radar and "deerhorn" antennae. Serving with 10 Staffel, Nachtjagdgeschwader 11, Night Fighter Unit, near Berlin, these few aircraft (alongside several single seat examples) accounted for most of the 13 Mosquitoes lost over Berlin in the first three months of 1945. However, actual intercepts were generally or entirely made using Wilde Sau methods, rather than AI radar-controlled interception. As the two-seat trainer was largely unavailable many pilots had to do their first flight in a jet in a single seater without an instructor.

Despite its deficiencies, the Me 262 was clearly signalling the beginning of the end of piston-engined aircraft as efficient fighting machines. Once airborne, it accelerated to speeds well over 800 km/h (500 mph), over 150 km/h (93 mph) faster than any Allied fighter operational in the European Theater of Operations.

The Me 262's top ace[4] was probably Hauptmann Franz Schall with 17 kills which included six four-engine bombers and ten P-51 fighters, although night fighter ace Oberleutnant Kurt Welter claimed 25 Mosquitos and two four-engined bombers shot down by night and two further Mosquitos by day flying the Me 262. The vast majority of Welter's claimed night kills were achieved in standard radarless aircraft, even though Welter had tested a prototype Me 262 fitted with Neptun radar. Another candidate for top ace on the aircraft was Heinrich Bär, who claimed 16 enemy aircraft while flying the Me 262.

[edit] Anti-bomber tactics
The standard approach against bomber formations, which were travelling at cruise speed, called for the Me 262 to approach the bombers from the rear at a higher altitude, diving in below the bombers to get additional speed before zooming up again to their level and opening fire with its four 30 mm cannon at 600 m (656 yard) range.

Allied bomber gunners found that their electric gun turrets had problems tracking the jets. However, due to the jets' straight-line approach, traverse rates were actually not as important as target acquisition itself, which was difficult because the jets closed into firing range very quickly and had to remain in firing position only very briefly using their standard attack profile.

Eventually new combat tactics were developed to counter the allied bombers defenses. Me 262s equipped with large numbers of R4M rockets would approach from the side of a bomber formation where their silhouettes were widest and, while still out of range of the .50 caliber guns, fire a salvo of these explosive rockets. The explosive power of only one or two of these rockets was capable of downing even the famously rugged B-17. While this tactic came too late to have a real effect on the war, it was nonetheless effective. This method of combating bombers became the standard until the invention and mass deployment of the guided missile. Some nicknamed this tactic the "Luftwaffe's Wolf Pack" as the fighters would often make runs in groups of two or three, fire their rockets, then return to base.

On 1 September 1944, USAAF General Carl Spaatz expressed the fear that if greater numbers of German jets appeared, they could inflict losses to the USAAF bombers heavy enough to cause cancellation of the Allied daylight bombing offensive.

[edit] Counter-jet tactics
Many accounts from Allied bomber crews cited that they were surprised by the speed of the Me 262. Allied intelligence was aware of German jet development, but not all combat units were fully briefed about the Me 262, and it is probably true to say that Allied intelligence slightly underestimated the speed of the Me 262.[citation needed]

Tactics against the Me 262 developed quickly to find ways of defeating it despite its great speed advantage. Allied bomber escort fighters (specifically P-51s) would fly high above the bombers— diving from this height gave them extra speed thus reducing the speed advantage of the Me 262. The Me 262 was less maneuverable than the P-51 and trained Allied pilots could catch up to a turning Me 262; but the only reliable way of dealing with the jets was to attack them in the takeoff and landing phase of their flight, and on the ground. Accordingly, Luftwaffe air fields that were recognized as jet bases were frequently bombed by medium bombers, and Allied fighters patrolled over the fields to attack jets that were trying to land on their bases. The Luftwaffe countered these moves by installing Flak alleys along the approach lines in order to protect the Me 262s from the ground, and providing top cover with conventional fighters during the takeoff and landing phase.

Another experimental tactic was installing nitrous oxide injection into Mustangs. When chasing an Me 262, the pilot could press a button injecting the nitrous oxide into the engine, producing a quick burst of speed.

Other Allied fighters that encountered the Me 262 included the British Supermarine Spitfire, Hawker Tempest and the Soviet Lavochkin La-7. The first recorded Allied destruction of a Me 262 was on 28 August 1944, claimed as destroyed by 78th FG pilots Major Joseph Myers and 2nd Lt. Manford O. Croy flying P-47s. Oberfeldwebel

panzerpete

04-14-2007, 01:04 PM

Hieronymus "Ronny" Lauer of I KG(J) 51, on a landing pattern crash landed his 262 to get away from the Allied fighters, which then destroyed the Me 262 in strafing attacks[5] The first Me 262 shot down in combat was on 5 October 1944 by Spitfire IXs of 401 RCAF. The 262 pilot was H.C. Butmann in WNr 170093 of 3./KG51. The Lavochkin was the only Soviet fighter to shoot down a German jet, with La-7 ace Ivan Nikitovich Kozhedub fighting and downing one Me 262 jet on February 15, 1945 over eastern Germany. Kozhedub apparently later said that his success was mainly due to the Me 262 pilot attempting to out-turn his more maneuverable plane.

[edit] High speed research

Me 262 interiorWilly Messerschmitt regarded the Me 262 as it went into production only as an interim type. His interest in high-speed flight that had led him to initiate work on swept wings starting in 1940 is evident from the advanced developments he had on his drawing board in 1944. While the Me 262 HG I (Hochgeschwindigkeit, high speed) that was actually flight-tested in 1944 had only small changes compared to combat aircraft, most notably a low-profiled canopy to reduce drag, the HG II and HG III designs were far more radical. The projected HG II variant combined the low-drag canopy with a 35° wing sweep and a butterfly tail. The HG III aircraft had a conventional tail, but a 45° wing sweep and the jet turbines embedded in the wing root.

Messerschmitt also conducted a series of carefully controlled flight tests with the series production Me 262. In these dive tests, it was established that the Me 262 was out of control in a dive at Mach 0.86, and that higher Mach numbers would lead to a nose-down trim that could not be countered by the pilot. The resulting steepening of the dive would lead to even higher speeds and disintegration of the airframe due to excessive negative g loads.

The HG series of Me 262 derivatives was estimated to be capable of reaching transonic Mach numbers in level flight, with the top speed of the HG III being projected as Mach 0.96 at 6 km altitude. Despite the necessity to gain experience in high-speed flight for the HG II and III designs, Messerschmitt undertook no attempts to exceed the Mach 0.86 limit for the Me 262.

After the war, the Royal Aircraft Establishment, at that time one of the leading institutions in high-speed research, re-tested the Me 262 to help with the British attempts at breaking the sound barrier. The RAE achieved speeds of up to Mach 0.84 and confirmed the results from the Messerschmitt dive tests as accurate. Similar tests were run by the Soviets. No attempts were made to exceed the Mach limit established by Messerschmitt.

After Willy Messerschmitt's death, the former Me 262 pilot Hans Guido Mutke claimed to be the first person to break the sound barrier on 9 April 1945 in a Me 262, in a "straight-down" 90° dive. This claim is disputed because it is only based on Mutke's memory of the incident, which recalls effects that other Me 262 pilots have observed below the speed of sound and a high airspeed indicator reading, but no altitude reading, which would be required to determine the actual speed. Furthermore, the pitot tube used to measure airspeed in aircraft can give falsely elevated readings as the pressure builds up inside the tube at high speeds. Finally, the Me 262 wing had only a slight sweep incorporated for trim (center of gravity) reasons and likely would have suffered structural failure due to divergence at high trans-sonic speeds.

[edit] Production
As the Me 262 was widely-regarded as the Luftwaffe's top priority, all expendable materials were put into 262 production. While Germany was bombed repeatedly, production of the Me 262 was dispersed into low-profile production facilities, sometimes little more than clearings in the forests of Germany and other occupied nations. Large, heavily protected underground factories were constructed to take up production of the Me 262, safe from bomb attacks, but the war ended before they could be completed. Per German doctrine at the time, several components of the Me 262 were built in forced labor camps. In the end, slightly over 1400 Me 262s of all versions were produced. Due to fuel shortages, pilot shortages, and the lack of many airfields that could support the Me 262 (concrete runways were recommended as the jet engines would melt tar runways), as few as 200 Me 262s made it to combat units.

[edit] Postwar evaluation, history and design influence

Reproduction of a Messerschmitt Me 262 at the Berlin Air Show 2006.After the end of the war the Me 262 as well as other advanced German technology was quickly swept up by the Americans, British and Soviets. Many Me 262s were found in readily-repairable condition and were confiscated. During testing, the Me 262 was found to have advantages over the early models of Gloster Meteor. It was faster, had better cockpit visibility to the sides and rear (mostly due to the canopy frame and the discoloration caused by the plastics used in the Meteor's construction) and was a superior gun platform; as the early Meteors had a tendency to snake at high speed and exhibited "weak" aileron response.[6] The Me 262 did have a shorter combat range than the Meteor.

The USAAF compared the P-80 and Me-262 concluding: "Despite a difference in gross weight of nearly 2,000 lb (907 kg), the Me 262 was superior to the P-80 in acceleration, speed and approximately the same in climb performance. The Me 262 apparently has a higher critical Mach number, from a drag standpoint, than any current Army Air Force fighter."[7] The Army Air Force also tested an example of the Me 262A-1a/U3 (US flight evaluation serial FE-4012), an unarmed photoreconnaissance version, which was fitted with a fighter nose and given an overall smooth finish. It was used for performance comparisons against the P-80. During testing in May-August 1946, the aircraft completed eight flights spanning four hours and 40 minutes. Testing was discontinued after four engine changes were required during the course of the tests, culminating in two single-engine landings.[8]

These aircraft were extensively studied, aiding development of early US and Soviet jet fighters. The F-86 Sabre was partially influenced by some of the features of the Me 262.[citation needed] The F-86 used a slat design similar to that of the Me 262 and some German parts were used on the prototype[citation needed].

The Czechoslovak aircraft industry continued to produce single-seater and two-seater variants of the Me 262 after World War II. These were kept flying as late as 1957. Both versions are on display at the Prague Aero museum in Kbely.

In January 2003, the American Me 262 Project completed flight testing to allow for delivery of near-exact reproductions of several versions of the Me 262 including at least two B-1c two-seater variants, one A-1c single seater and two "convertibles" that could easily be converted between the A-1c and B-1c configurations. All are powered by General Electric J85 engines and feature additional safety features such as upgraded brakes and strengthened landing gear. The "c" suffix refers to the new J-85 powerplant and has been informally assigned with the approval of the Messerschmitt Foundation in Germany.
[edit] The Me 262 in popular culture
In the PC flight simulator Chuck Yeager's Air Combat, a virtual Chuck Yeager voiced by himself, states that Allied pilots used the term "Blow Job" for Me 262s.
The American hard rock band Blue Öyster Cult portrayed an Me 262 on the cover of their 1974 album Secret Treaties. The album also contains a song, Me 262, inspired by the real-life jet. The lyrics are written from the point of view of a Luftwaffe pilot on a bomber interception mission in April 1945. The song is generally technically accurate, correctly identifying the aircraft's Junkers Jumo 004 engines, and describing how the pilot's Me 262 is armed with R4M air-to-air rockets, which were operational at that late stage in the war.
Clive Cussler's famous fictional character Dirk Pitt owns an Me 262, which he acquired when he helped excavate a hidden airfield that held a number of the aircraft.
The game B-17 Flying Fortress:The Mighty 8th! features ME-262s that the player can fly if he/she chose an interceptor role.

[edit] References
^ Price 2007, p. 36-37. Quote: "In April (1944), a service test unit, Erprobungskommando 262 was formed at Lechfeld in Bavaria...
^ a b Loftin, L.K. Jr. Quest for performance: The evolution of modern aircraft. NASA SP-468. [1] Access date: 22 April 2006.
^ Smith 1971, p. 103. Quote: "On 25 July 1944, a Me 262 from EK262 recorded the world's first interception of an enemy aircraft by a jet fighter. A photo-reconnaissance Mosquito from No. 544 Squadron RAF was flying over the Munich area when the observer, F/O Lobban spotted an enemy aircraft in the distance. The pilot, F/Lt Wall, quickly accelerated the machine, but was surprised to see that the enemy was still closing rapidly. After evading five firing passes from the Me 262 (Editors's note: piloted by Lt. Alfred Schreiber), Wall managed to dive into a cloud bank, eventually crash landing the Mosquito back at Fermo, near Venice."

[edit] Related content
Wikimedia Commons has media related to:
Messerschmitt Me 262Related development
Focke-Wulf Ta 183 - advanced jet fighter designed as the successor to the Messerschmitt Me 262.

panzerpete

04-14-2007, 01:05 PM

[edit] Variants

Me 262 A-1a circa 1944
Me 262 A-1a/U4
Me 262 B-1a/U1 or B-2a night fighter
Me 262 A-1a
Me 262 B-1a/U4A-1a Schwalbe - production version Jäger (fighter) and Jabo (from German: "Jagdbomber", fighter bomber).
A-1a/U1 - single prototype with a total of six nose mounted guns, two 20 mm MG 151 cannon, two 30 mm MK 103, and two 30 mm MK 108 cannon.
A-1a/U2 - single prototype with FuG 220 Lichtenstein SN 2 radar array and Hirschgeweih antenna array in order to test the Me 262 as a night-fighter.
A-1a/U3 - reconnaissance version modified in small numbers, fitted RB20/30 cameras mounted in the nose (sometimes one RB 20/20 and one RB 75/30). Some retained one 30 mm cannon as armament, but most were unarmed.
A-1a/U4 - two prototypes with a 50 mm tank cannon in nose.
A-1b - as A-1a but powered with BMW 003 engines. Few built- two are known to have existed at experimental establishments; maximum speed of 497 mph (800 km/h).
A-2a Sturmvogel - definitive blitzbomber version with only two guns.
A-2a/U1 - single prototype with advanced bombsight.
A-2a/U2 - two prototypes with glazed nose for accommodating a bombardier.
A-3a - proposed ground attack version.
A-4a - reconnaissance version.
A-5a - definitive reconnaissance version used in small numbers at end of the war.
B-1a - two-seat trainer.
B-1a/U1 - B-1a trainers converted into provisional night fighters, FuG 218 Neptun radar
B-2 - proposed night fighter version with stretched fuselage.
C-1a - single prototype of rocket-boosted interceptor with Walter rocket in tail.
C-2b - single prototype of rocket-boosted interceptor with BMW rockets mounted in engine nacelles.
C-3a - single prototype of rocket-boosted interceptor with Walter rockets in belly pack.
D-1 - proposed variant to carry Jagdfaust mortars.
E-1 - proposed cannon-armed variant based on A-1a/U4.
E-2 - proposed rocket-armed variant carrying up to 48 R4M rockets.
Japanese design patterned after the Me 262:

Nakajima Kikka
Postwar variants:

Avia S-92 - Czech built A-1a
Avia CS-92 - Czech built B-1a
A-1c - American privately built, based on A-1a configuration
B-1c - American privately built, based on B-1a configuration
A/B-1c - American privately built, convertible between A-1a and B-1a configuration

[edit] Operators
Czechoslovakia (post-war)
Germany: Luftwaffe
General characteristics
Crew: One
Length: 10.60 m (34 ft 9 in)
Wingspan: 12.51 m (41 ft 0 in)
Height: 3.50 m (11 ft 6 in)
Wing area: 21.7 m² (234 ft²)
Empty weight: 3,800 kg (8,400 lb)
Loaded weight: 7,130 kg (15,720 lb)
Max takeoff weight: 6,400 kg (14,100 lb)
Powerplant: 2× Junkers Jumo 004B-1 turbojets, 8.8 kN (1,980 lbf) each
Aspect ratio: 7.23
Performance
Maximum speed: 870 km/h (541 mph)
Range: 1,050 km (652 mi)
Service ceiling: 11,450 m (37,565 ft)
Rate of climb: 1,200 m/min (3,900 ft/min)
Thrust/weight: 0.28
Armament
4x 30 mm MK 108 cannons (A-2a: two cannons)
2x 250 kg (550 lb) bombs (A-2a only)
24x 55 mm (2.2 in) R4M rockets

panzerpete

04-14-2007, 01:08 PM

remember, all from wikipedia, the article i got this from has citations too but i have not put them in, but i can, just request them.

it is in so many posts because the article was almost 30,000 characters long

Digger

04-14-2007, 04:43 PM

Thanks panzerpete, that pretty much covers the basics and I'll post something later tonight for anyone who requires further reading on the subject.

Still by virtue of it's protracted development, late entry to the war, continued problems and poor quality of engines, difficulties of working the type up to service level and poor loss to kill ratio, the Me 262 was not a great fighter.

If the war had dragged on, then it would have had a legitimate claim to being a great fighter.

Regards digger.

Panzerknacker

04-14-2007, 06:49 PM

continued problems and poor quality of engines,

Well I think you get the point my dear Digger, there is difference between "poorly manufactured" (wich was not) and "poor quality materials" ( wich was sometimes).

Is also worth to note that most of the destroyed Me-262 were attacked in the groud or in the fianl aproach to their airfield, thing that deprived the Schwalbe to his best characteristics.

Also the plane was undermined by several bad tactical desitions and unnecessary delays wich hampered it to display his potential.

Me-262A-1/a, EKdo 262.

http://i10.tinypic.com/4df1tub.jpg

http://i16.tinypic.com/344b5s7.jpg

http://i11.tinypic.com/47s2gci.jpg

http://i11.tinypic.com/3yhy73l.jpg

There was however a lot of Me-262 aces like Galland, Bär, Steinhoff, etc.

One pilot of the JV 44 destroyed 2 P-51 in 3 minutes in his first sortie.

Raven

04-15-2007, 01:21 AM

Wow his first sortie, that's pretty impressive.

I've always thought if Hitler hadn't insisted it be a bomber it may have made a change to the war.

Of course if Germany had invested the time and costs into creating or upgrading their current piston-engine fleet I imgagine the outcome would have been more effective.

Digger

04-15-2007, 06:46 AM

Just to let you guys know, this thread was not started by me, it was shifted from another thread. I doubt I would have chosen the title for this thread.

To clear one thing up, I have never said the Me 262 was a bad aircraft, rather it was an aircraft yet to reach it's potential, when the war ended.

Engine development was it's biggest stumbling block, remembering this was cutting edge technology at the time, and it was this developmental problems with the Jumo engines which caused most of the delays. Hitler's decision to convert Me 262s to fighter bombers was not the cause for delay.

And yes, there was evidence of poor manufacturing in the Me 262, but this was the symptom of the times with most manufacturing suffering air attacks, disruption of supplies, shortages of strategic materials and a largely unskilled workforce. Many of the workforce in German war industry, were poorly treated, starving, were beaten(sometimes to death), had minimal skills training and because of these reasons good manufacturing principles lapsed dramatically throughout 1944.

In some cases there was evidence of sabotage, particuarly in engines, but to what degree this effected overall production is hard to say. In spite of these difficulties Messerschmitt did get the Me 262 into service, a remarkable achievment.

Regards digger.

Panzerknacker

04-15-2007, 12:12 PM

Yeap I splitted the topic, the Me-262 is interesting enough to made a thread of it.

most manufacturing suffering air attacks, disruption of supplies, shortages of strategic materials

I think those (in despite the others you named ) are the most important causes, the german ended assemblig jet fighters in the woods.

Wow his first sortie, that's pretty impressive.

I've always thought if Hitler hadn't insisted it be a bomber it may have made a change to the war

That was Walter Schuck, he scored 206 victories and was awarded the Knight's Cross with Oak Leaves. In April 1942 he was sent to the bitterly cold Eismeer Front with 7./JG 5 at Petsamo, Finland. In March 1944 he shot down seven Boston bombers in a single day. On 1 August 1944 he was promoted to Staffelkapitän of 10./JG 5. He was transferred to the West to fly the Me 262 and was appointed Staffelkapitän of 3./JG 7 on 24 March 1945. He shot down eight aircraft while flying the Me 262, including four B-17s on 10 April. He was forced to bail out on the same mission.

http://www.highironillustrations.com/aviation_pics/schuck.jpg

http://www.civilwarmall.com/bookseller/images/Schuck2.jpg

Raven

04-15-2007, 10:03 PM

Amazing. Thanks for the information Panzerknacker.

Librarian

04-16-2007, 10:58 AM

As usually, honorable ladies and gentlemen, Mr. Digger has the point in this case:

… it was an aircraft yet to reach it's potential, when the war ended… Engine development was it's biggest stumbling block, remembering this was cutting edge technology at the time, and it was this developmental problems with the Jumo engines which caused most of the delays.

Indeed, engine development was Me 262’s biggest faltering obstruct, but it has to be emphasized that this gas turbine jet power plant actually was a compromise between engineering desires and available materials and production facilities.

Outstanding evidence of technological compromises resulting from lack of strategic materials is situated in the fact that more than 7% of the engine intake-air was bled-off for cooling purposes. Despite this, however, most engines were found to have a service life of about only 10 hr., against a "design life" of 25 – 35 hr. Additional compromises are evident in the design, which shows that the production engineers were undoubtedly hampered by lack of both plant facilities and adequate skilled labor, but the main reason for a delay in Me 262 production was the diversion of critical materials into U-boat production and other projects late in the war, ant that verity forced Junkers to produce the 004 B engines with only 1/3 of the high grade steel that had been used in the very first 004A engines. It was a disastrous concession for the Me 262.

It has to be also emphasized that these failures were actually anticipated to some extent and the Me 262 was designed to permit really rapid engine changes.

Contrary to popular belief, the Jumo 004 was a fairly sound performer when first-rate steel alloys of excellent heat-resistant qualities were used just after the German capitulation, and it was proved by US post-war tests that simple application of different materials made possible to get average endurance of the turbines up to 150 hours service in actual flight tests, and up to 500 hours on the test stand.

http://i10.photobucket.com/albums/a137/Langnasen/JunkersJumo004.jpg

Junkers Jumo 004 B - Cross-Section

The Junkers Jumo 004 B was the first large-scale produced axial-flow aircraft gas turbine engine, developed by Dr. Ing. Anselm Franz from Junkers. Even though Dr. Franz was familiar with centrifugal compressors from his previous work on piston-engine superchargers, he opted for an axial compressor design because he was convinced that the low frontal engine area cross-section was of fundamental importance for a high-speed airplane aerodynamics and that aforesaid low-drag gains could be achieved with an axial design only. This also turned out to be a correct choice as the Gloster Meteor was delayed by problematic airframe integration issues caused by its large, centrifugal compressor equipped Derwent engines.

http://i10.photobucket.com/albums/a137/Langnasen/rolls-RoyceDerwent1.jpg

Rolls-Royce Derwent - Cross Section

The axial compressor concept was based on the steam-turbine experience achieved by AEG in Berlin and it didn’t use a vortex design that was characteristically used by British engineers in their own constructions.

In 1936, when the first work on turbojets began, a high-temperature Krupp-made steel alloy known as P-193 was available. This material, which contained nickel, chromium, and titanium, could be given good high-temperature strength by means of solution treating and precipitation hardening. Dr. Anselm Franz initially used an improved version of P-193 known as Tinidur – austinitic 'stainless steel' like steel alloy with 6% titanium, 18% nickel 12% chromium with the balance of steel.

The first turbine blades of the Jumo 004 A version were solid ones. Early tests showed that even supposedly identical blades would have a large scatter life. By 1944, Junkers had solved the problem and obtained uniform quality of the blade by close control of manufacturing, especially of the critical forging process. Attempts to produce hollow blades by folding flat sheets of Tinidur and welding down the trailing edge resulted in failure, as Tinidur could not be welded. Eventually, a deep drawing process was used, in which the stock for the blade was a flat circular blank. Hollow blades could be manufactured faster than solid blades by this process.

However, constant lack of Nickel caused a forced and rapid abandonment of the previously used materials. Chromite ore, from which is derived chromium, an element essential for the manufacture of stainless steel was evaluated as one of the few raw materials that were essential for the German war industry and for which there were no fully adequate sources within German territory, was very scarce.

At the beginning of the war Germany had an estimated stockpile of about 250,000 tons of chromite, which had been accumulated by heavy purchases in Africa, Turkey, and the Balkans in the late 1930s. By 1941 the only European source within the German range available for new deliveries of ore was the Balkans, and the only accessible source outside occupied Europe was Turkey, with another one potentially reachable replacement – a mammoth Nikopol manganese ore district - located in Ukrainian part of the USSR. In mid-1944, however, Germany’s loss of all remaining chromite as well as manganese ore supplies was disastrous: the Soviets recaptured Nikopol and succeeded in denying an important source of manganese to the Germans. Subsequently, total German steel production declined from the 35 million tons in 1943 to 2 millions tons per quarter by the end of 1944, and Germany was forced to abandon the production of high alloy-steels. The output of engineering steels declined by two-thirds, and the special steel available for military ordnance declined from nearly 2.5 million tons to less than 900,000 tons. The manufacture of airplanes, tanks, motor vehicles, tank shells, U-boats, and almost the entire gamut of artillery has suffered, but German engineers were still very devoted and skillful, and they successfully developed some even today very intriguing and highly original, even today applicable Ersatz (substitute) solutions.

Previously mentioned forced abandonment of Tinidur alloy, with 30-percent nickel content, strained Krupp toward development of the alloy called Cromadur, which was actually better than their earlier attempt, as Cromadur proved easy to weld. The process of folding the blade flat and welding it turned out to be superior to deep drawing, so the Cromadur blades proved more reliable than the Tinidur blading despite Cromadur's lower creep strength!

However, intensive air cooling was essential, and it was used throughout the engine. A later version of the 004B engine had hollow, air-cooled stator vanes, because these parts were the most critical ones. Compressor discharge-air was used to cool the blades. With hollow blades made out of Cromadur-alloy sheet metal, the complete 004B engine contained less than 2.3 kg of chromium. Due to these improvements the first production model of the 004B weighed 45.5 kg less than the 004A! Additional modifications were made to the first compressor stages too. A series of 100-hour tests were completed on several engines, and time between overhaul of 50 hours was achieved.

http://i10.photobucket.com/albums/a137/Langnasen/Jumo004-compressedairflow.jpg

Junkers Jumo 004 – Compressed Air Cooling

Cooling airflow was derived from between the fourth and fifth compressor stages, and led to the double skin around the combustion-chamber assembly. Most air passed down one exhaust cone strut to circulate inside the cone and through small holes to cool the downstream face of the turbine disk. Air was also taken in through three tunnels in two of the casting ribs and into the space between the two plate diaphragms in front of the turbine disk. Most of this air passed through the hollow turbine nozzle guide vanes, emerging through slits in the trailing edges.

http://i10.photobucket.com/albums/a137/Langnasen/Jumo004commandline.jpg

Junkers Jumo 004 – Motor Management Schematics

Forced end of the part I… To be continued.

Librarian

04-16-2007, 11:04 AM

Part II

The turbine, designed in collaboration with AEG, had a degree of reaction of 20 %, which represented a compromise between AEG, which wanted less, and Junkers, which wanted more (from afterburner considerations). The single-stage turbine had 61 blades fixed to the turbine disk by a formed root and kept in position by rivets. The production version had air-cooled hollow blades. A movable 'bullet' was mounted in the tailpipe and controlled by a servomotor to vary the nozzle area.

On the other side of the hill situation was pretty different. In England the early development of age hardening nickel alloys was influenced by works of on the nickel-chromium heat and oxidation resistant alloys which showed the outstanding characteristics of the 80% nickel, and 20 % chromium composition (Tapsel & Bradley, 1925). Thus when in the early 1940s, at the request of Britain's Air Ministry, different private company scientists worked feverishly to solve the problem of appropriate materials for emerging designs in jet and gas turbine engines, that what became one of the most noted contributions during the war by metallurgists (Pfeil, Allan and Convay from the Henry Wiggin & Co. Ltd.) facilities in Birmingham, was the specific re-invention of an low-ferrite alloy for jet-propelled aircraft engines.

http://i10.photobucket.com/albums/a137/Langnasen/Nimonic80alloyblades.jpg

Nimonic 80 Alloy Turbine Blades, De Havilland Goblin II Engine

This new nickel alloy called "Nimonic 80" allowed the jet engine's turbine parts, particularly the blades, to operate for long periods under tremendous stress, under high heat and corrosive exhaust, without deforming or melting. This new non-ferrite alloy was far superior to all German constructive metal alloys used in the aircraft industry. After the war, Nimonic 80 set the stage for a revolution in jet-propelled aviation.

For much of the past century the key location for this essential metal was the legendary Sudbury Basin, with the South Pacific island of New Caledonia coming a distant second.

And finally an additional historiographic remark: After the WW2 Dr. Anselm Franz immigrated to the United States, where he worked for the U.S. Air Force from 1946 until 1950. In 1951, he joined Avco Lycoming and soon moved to Stratford (Connecticut), where he established the gas-turbine department of the aforementioned company, being responsible for several successful engine-development programs, including the T53 (which powers the U.S. military's AH-1S Cobra, Grumman OV-1 Mohawk, and Bell UH-1 Huey helicopters) and T55 series of turbo-shaft engines, as well as the T55 high-bypass turbofan (named the ALF502). In the 1960s Dr. Anselm Franz led a team to design the three-spool, 1,500 shaft-horsepower AGT-1500 V gas turbine, the power plant for the U.S. M1 Abrams main battle tank. He retired as vice president of Avco Lycoming in 1968.

http://i10.photobucket.com/albums/a137/Langnasen/DrFranzAnselm.jpg

Dr. Ing. Anselm Franz, Chief Engeneer of the Junkers Jumo 004 Development Program

But that is a completely different story…

As always honorable ladies and gentlemen - all the best!;)

Twitch1

04-16-2007, 12:05 PM

Say all you want about the first jet turbines. The fact is that German engineers were aware of the initial shortcomings and had the situation in hand with the 2nd generation of engines that were being developed.

Panzerknacker

04-16-2007, 12:39 PM

Nice drawing and comments Librarian, the titanium was also a metal wich was completely unavailable for those times in Germany.

Say all you want about the first jet turbines. The fact is that German engineers were aware of the initial shortcomings and had the situation in hand with the 2nd generation of engines that were being developed.

They were aware but due the war situation they were unable to cure it completely, still some 1400 Me-262s were completed, not all used in combat.

I believe (firmly) that the Me-262 was a powerful combat machines despite his shorcomings.

More devastating than all the material poorness was the 25th May order of A.H who said every Me-262 should be a bomber.

http://www.mundosgm.com/galeria/me2626tb.jpg

Chevan

04-16-2007, 12:41 PM

Thanks for detailed engeen material mst. Labrarian.
You've wondered us as always by your extremaly wide and deep-specific knowleges at the same time.;)
BTW i have to add that inspite of engeens problems the Me-262 was the much better aircraft then the first British Meteor Mk i.
The Me-262 had a much more speed and a much more firepower 4x30 mm gun !!! This was a uber-wearpon which could really finish the allies strategic aviation if it was done in the 1944 and in enough quantity.
P.S. oh my god it seems i become a one more "german wearponry soccer" in here :D
what to do?

Panzerknacker

04-16-2007, 12:49 PM

P.S. oh my god it seems i become a one more "german wearponry soccer" in here :D
what to do?

What to do?...I guess that you might enjoy the conversation while eating some knackwurst and bier. :cool:

http://www.luft46.com/dsart/ds262-3.jpg

Chevan

04-16-2007, 12:56 PM

What to do?...I guess that you might enjoy the conversation while eating some knackwurst and bier. :cool:

http://www.luft46.com/dsart/ds262-3.jpg
I would enjoy but where you are when you are needed?
BTW is it an Me-262 HG II perspective modification which were never finished?

Panzerknacker

04-16-2007, 12:59 PM

I am always available my dear russian sargeant. ( i did receive your PM)

Indeed that is an Me-262HG "stüfe 1" ( stage 1)... nice isnt ?

Me 262 B-1a (http://www.lexikon-der-wehrmacht.de/Waffen/Me262-R.htm#B1) des KG 54 in Giebelstadt

http://www.lexikon-der-wehrmacht.de/Bilder/Me262/me262B1a-3%20IKG54%20Giebelstadt.jpg

Chevan

04-16-2007, 01:08 PM

I am always available my dear russian sargeant. ( i did receive your PM)
I've never doubt in it comrade general;)

Indeed that is an Me-262HG "stüfe 1" ( stage 1)... nice isnt ?

Very nice.
Could you prove for other our comrades ( mostly from the "misty Albion") that this aircraft could fly enough good.
Becouse some our members , who are the specialist on aerodinamic field ;) recently tryed to prove me that the Me 262 HG i/II/III simply was not able to fly.

Cheers.

pdf27

04-16-2007, 02:37 PM

Contrary to popular belief, the Jumo 004 was a fairly sound performer when first-rate steel alloys of excellent heat-resistant qualities were used just after the German capitulation, and it was proved by US post-war tests that simple application of different materials made possible to get average endurance of the turbines up to 150 hours service in actual flight tests, and up to 500 hours on the test stand.
True, although it should be pointed out that Allied engines at this point in time were happily managing over 1,000 hours in service with what were IIRC higher TITs and with no cooling air.

The Junkers Jumo 004 B was the first large-scale produced axial-flow aircraft gas turbine engine, developed by Dr. Ing. Anselm Franz from Junkers. Even though Dr. Franz was familiar with centrifugal compressors from his previous work on piston-engine superchargers, he opted for an axial compressor design because he was convinced that the low frontal engine area cross-section was of fundamental importance for a high-speed airplane aerodynamics and that aforesaid low-drag gains could be achieved with an axial design only. This also turned out to be a correct choice as the Gloster Meteor was delayed by problematic airframe integration issues caused by its large, centrifugal compressor equipped Derwent engines.
BS. AA Griffith at the RAE in Farnborough made the same fundamental mistake. For a peacetime programme where they had time to get it right, it may have been true. For a wartime emergency programme where they had to get it right first time with limited resources, it was deeply wrong. The point about the Gloster Meteor is savagely flawed too - despite these supposed "issues", it started development work later and yet entered squadron service before the Me-262 did.
The absolute genius of Frank Whittle - and I make no apologies about using the word - was not in the invention of the Turbojet engine. The concept had been around for quite some time, and he was merely refining it a bit. His genius was in realising that it could be made with simple parts that were already well understood, fettled a bit, and it would beat any engine then in service or on the drawing board by a huge margin. His use of centrifugal compressors is a large part of this - axial flow compressors even today are huge, heavy, a major pain to design right and suffer from stall/surge problems. Centrifugal compressors don't, and the only reason that they are nowadays limited to a few applications like helicopter engines is simply due to ducting problems when stacking compressors, rather than issues of frontal area.
It is worth noting that Whittle-type engines powered all the first generation of postwar jet aircraft, despite the supposedly "superior design" of the Jumo-type engines being freely available. Given that the Soviets had full access to the German plans - including those for the second-generation engines - and yet decided to build a copy of the RR Derwent instead is to me further evidence that your thesis that the Jumo-004 wasn't too bad really does not hold water. It wasn't until engines like the Armstrong-Siddely Sapphire and RR Avon became available in the 1950s that axial flow engines gained widespread acceptance.

pdf27

04-16-2007, 04:35 PM

The turbine, designed in collaboration with AEG, had a degree of reaction of 20 %, which represented a compromise between AEG, which wanted less, and Junkers, which wanted more (from afterburner considerations).
I have grave doubts that this was the reason. I really can't see how the degree of reaction would substantially affect the reheat stage. All it does is change the design of the final stator. If you're trying to have a rotor as the final stage, then the degree of reaction is critical for far more important things than reheat flame stability. Incidentally, the Jumo 004C was only ever a paper design which would most likely have had major problems in getting it to work. All of the first generation reheat designs proved to be much more troublesome than anticipated, largely due to flame stability problems. I suspect there will also have been some issues with the particular flow regime they operated in and the need for adjustable nozzles to take full advantage - moveable shock cones just don't cut it.

I should probably declare a bias here. I read Aero & Mechanical Engineering at exactly the same place - Peterhouse, Cambridge - that Frank Whittle read for the Mechanical Sciences Tripos, the forerunner of the current engineering course. Thus my views on him may not be entirely objective, although I have done my best.

pdf27

04-16-2007, 05:06 PM

Could you prove for other our comrades ( mostly from the "misty Albion") that this aircraft could fly enough good.
Becouse some our members , who are the specialist on aerodinamic field ;) recently tryed to prove me that the Me 262 HG i/II/III simply was not able to fly.
That would be me I suspect ;)
To be fair I've never tried to prove that it would be unflyable, but rather that the German performance figures were wildly implausible and it would most likely have been a complete dog.

Panzerknacker

04-16-2007, 07:26 PM

Gallands report on the Me-262:

http://img177.imageshack.us/img177/7953/me262v1iv8.jpg

Berlin, 25 May 1943:

Most esteemed Herr Generalfeldmarschall!

On Saturday, the 22nd of the month, I tested the ME 262 at Augsburg in the presence of Oberst Petersen and other persons from the Technical Office. I would have preferred to report personally to the Generalfeldmarschall and also elaborate on other matters, however I was so occupied after my visit to Sicily that there was simply no time. The Reichmarschall has ordered me to report today.

Concerning the Me 262, I beg to state the following:

1.) The aircraft represents an enormous leap forward, it would give us an unimaginable lead over the enemy if he adheres to the piston engine.

2.) In-flight handling of the airframe is impressive.

3.) The power plants are fully convincing, except during take-off and landing.

4.) The aircraft offers entirely new tactical prospects.

I beg to submit the following proposal: The Fw 190 D is under development, its performance should match the Me 209's in all respects. The performance of the two types, however, will not be superior to the enemy's models, particularly at altitude. The only progress seems to be in armament and higher speeds.

Conclusion:

a) Me 209 be discontinued
b) Total fighter production to switch from the Fw 190 with BMW 801
to the Fw 190 with DB 603 and Jumo 213 respectively.
c) The construction and industrial capacities thus released to be
concentrated on the Me 262, with immediate effect.
I shall report immediately on my return.

Heil Hitler! Herr Generalfeldmarschall your most obedient servant.

http://img20.imageshack.us/img20/5026/dibujoqq1.jpg

Sources:

"German jet aces of WW2" Osprey Military publishing

"Warplanes of the Luftwaffe"

http://home.att.net/~jv44/

Raven

04-16-2007, 10:18 PM

Quite interesting.
Just another, what if scenario.

Chevan

04-17-2007, 03:21 AM

That would be me I suspect ;)

Do yoy know the another aerodinamic specialists in here ?:D

To be fair I've never tried to prove that it would be unflyable, but rather that the German performance figures were wildly implausible and it would most likely have been a complete dog.
The pictures of models which i've showed at you just the prototipes that just explain the tendency of Messersmith to use the sweptback wing ( firstly in world for the jet aviation).

Cheers.

Digger

04-17-2007, 06:38 AM

One of the great myths surrounding the Me-262 was Hitler's demand the Me 262 be produced as a bomber severly delayed or impacted on the Me 262 production programme.

Nothing could be further from the truth. The notorious '-Fuhrer-Befhel was tactly ignored and in April 1944 when Me-262 production was barely at a trickle Hitler discovered at a conference with Goering, Milch and Saur not one Me-262 had been delivered as a bomber. Hitler's famous rage exploded and he declare,"Not a single one of my orders has been obeyed."

It was not until July 1944 the first Sturmvogel(bomber version) appeared and there had not been any delay in production due to the relative simplicity of the bomb pylons and release mechanism.

Although development of the Jumo 004 engine had been frozen in June 1944 to facilitate faster production, engine production could not keep pace with airframe production, with 59 Me 262's delivered in July, 20 in August, 91 in September, 117 in October for a total of 315 aircraft.

In early November 1944 the Fuhrer Befhel was cancelled and the bomber units which had been formed played little role in the combat of early 1945.

Regards digger.

pdf27

04-17-2007, 01:16 PM

Do yoy know the another aerodinamic specialists in here ?:D
Yeah, I do actually. At one point there were five of us on here (at the height of the whack-an-Ironman phase). Just look back through some of the archived threads to see who they were though. The only ones I can remember were Walther and Crab-to-be.

Panzerknacker

04-17-2007, 04:15 PM

One of the great myths surrounding the Me-262 was Hitler's demand the Me 262 be produced as a bomber severly delayed or impacted on the Me 262 production programme.

Nothing could be further from the truth. The notorious '-Fuhrer-Befhel was tactly ignored and in April 1944 when Me-262 production was barely at a trickle Hitler discovered at a conference with Goering, Milch and Saur not one Me-262 had been delivered as a bomber. Hitler's famous rage exploded and he declare,"Not a single one of my orders has been obeyed."

It was not until July 1944 the first Sturmvogel (bomber version) appeared and there had not been any delay in production due to the relative simplicity of the bomb pylons and release mechanism.

Yes, but Hitler also orderer an devoted fast bomber variant, the convertion to this aircraft wasnt so simple, it need more fuel and reinforcement in the fuselage. ( the sturmvogel was merely a Fighter bomber)

Later I will put more on that.

Librarian

04-17-2007, 07:22 PM

The fact is that German engineers were aware of the initial shortcomings and had the situation in hand with the 2nd generation of engines that were being developed.

Absolutely agreed, my dear Mr. Twitch1. BTW: I think that soon we will be able to share our contemplations about one mutually common personal love – about Packard and the WW2 war effort of the previously mentioned True Pride of the American Engineering Herritage. Although I do prefer the 1941 Clipper, I think that we will have an interesting conversation.

Thanks for detailed engeen material…

Oh, not at all, my daer Mr. Chevan. Engineering history always represented an substantial part of my private interests, and I am assuring you that some till now unpresented materials concerning perspectives and results of different Soviet engineering efforts will be posted here as well. And I think that you will be able to see some rare examples of true constructive ingenuity in that case too.

BS

Oh, please my dear Mr. Pdf27: this idiom is absolutely inappropriate for an Officer and a Gentlemen.

True, although it should be pointed out that Allied engines at this point in time were happily managing over 1,000 hours in service …

Would you be so kind to present the resources, my dear Mr. Pdf27? You see, I was able to find the officially distributed information that J33 jet-engine, for example, demonstrated a median life of only 151 hours before general overhaul due to poor stress-rupture properties. Please, just follow this link:

http://209.85.135.104/search?q=cache:knPWdNq9O5MJ:ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19620006009_1962006009.pdf+median+life,+J33&hl=en&ct=clnk&cd=2&gl=hu

and with no cooling air

With some curiously astonishing exceptions, my dear Mr. Pdf 27, peculiarly connected with another axial-flow jet engine. This time the British one.

http://i10.photobucket.com/albums/a137/Langnasen/MetropolitanVickersF2.jpg

Metropolitan Vickers F-2 – Cross Section

For a wartime emergency programme where they had to get it right first time with limited resources, it was deeply wrong.

Well, in that case, my dear Mr. Pdf27 I think that we can pronounce the whole genuine early American jet-engine design activity as a completely erroneous waste of time and money, and also to enunciate that aforesaid crime was committed by a group of staggering engineering idiots misfortunately positioned in the high places. Of course, I do have a completely opposite opinion. Personally I think that they were very good and completely capable professionals, obsessed with constructive perfectionism. What do I mean under by that? Well, I think that I shall be able to adequately explain this pretty personal, but theoretically well corroborated personal stance.

As you know, early in February of 1940 U.S. National Committee on Aeronautics established a Special Committee on Jet Propulsion, headed by Dr. William F. Durand, eminent aerodynamicist at Stanford University. Durand's interest in turbine machinery directed the NACA study almost entirely towards gas turbine engines. Curiously, from the very start the axial compressor solution was chosen as the best way to go, and that was explained by the smaller frontal area and higher potential pressure ratio of this engine type. However, although the axial compressor was lighter and more compact it was very well known that this solution represents quite a problematic answer, because it demanded knowledge of complex axial-flow aerodynamics. The complex movement of air across the blades of several stages presented a real challenge to the designers. The fabrication of the complicated compressors in those times without CAD/CAM technology was a genuine nightmare. Produced vibrations, caused by instable internal air-flow, created the danger that compressor blades might fly off in all directions. Nevertheless, the simpler solution found by Mr. Whittle and Mr. von Ohain - the centrifugal compressor - miraculously got away from the visage of those turbine experts within the Committee. The question is – why?

Personally, I think that part of the answer was already elucidated by a renowned N.A. Cumpsty, Head of the Whittle Laboratory, who has pointed out that the centrifugal compressor was used by Mr. Whittle because of the known difficulty of making an axial compressor. With a centrifugal compressor the use of the knowledge connected with pumps was obtainable, and - unlike the axial compressor (deeply connected with steam turbines!) - substantial pressure rise was producible, no matter how badly the aerodynamic of a design actually was calculated.

By directing the air flow radially outwards the centrifugal compressor, generally, always complicates the layout of the engine and obligatorily creates a larger frontal area; this becomes a more serious problem as the flight speeds approach the speed of sound. The centrifugal flow compressor employs an impeller to accelerate the air and a diffuser to produce the required pressure rise. Flow exit's a centrifugal compressor radially (at 90° to the flight direction) and it must therefore be redirected back towards the combustion chamber, resulting in a additional drop in thermodynamic efficiency.

An engine design using a centrifugal compressor, at least theoretically, allways will have a larger frontal area than one using a axial compressor. This is partly a consequence of the design of a centrifugal impeller, and partly a result of the need for the diffuser to redirect the flow back towards the combustion chamber. As the axial compressor needs more stages than a centrifugal compressor for the equivalent pressure rise, an engine designed with an axial compressor will be longer and thinner than one designed using a centrifugal compressor. This, plus the ability to increase the overall pressure ratio in an axial compressor by the constant addition of extra stages, has led to the use of axial compressors in most engine designs.

It seems also that Mr. Whittle’s choice of a centrifugal compressor for the WU (Whittle Unit) actually was influenced by his previous association with BTH (British Thompson Houston) of Rugby, who actually built WU, as BTH were in a position to assist with compressor design data.

Mr. Whittle was personally well aware that the axial flow compressor had the potential for a mass flow far in excess of the centrifugal compressor, however as engineers and scientists had not resolved the complex aerodynamic problems connected with the axial flow, he took the decision to use the proven, simple and undemanding centrifugal compressor.

It is of interest to note here that by 1942 centrifugal compressors were reaching the limits of efficiency due to the efforts of an almost unknown, but indeed excellent British engineer, who has specialized in aerodynamics - Dr. Stanley Hooker.

Aerodynamisist Dr. Stanley Hooker, hired by Mr. Ernest Hives of Rolls-Royce, was given the responsibility for the development of centrifugal compressors for aircraft piston-engines, such as the Rolls-Royce Merlin. Those more elderly perhaps will remember the fact that Mr. Stanley Hooker was some time ago brought out of retirement by Rolls-Royce, more precisely back there in 1970, in order to resolve the aerodynamic problems of the RB211 which pushed Rolls-Royce into near bankruptcy.

Dr.David Smith, another brilliant British engineer, a mathematically extraordinarily talented Scot living in Bowden, Cheshire, was subsequently employed by Metropolitan Vickers in Trafford Park, Manchester. Intriguingly, Mr. Smith had also written several mathematical papers on the problems of steam turbine rotor stability. This analytical contribution was crucial for the full-grown development of the axial-flow jet engines.

And so, in the same month when the US Special Committee on Jet Propulsion was formed, engineering representatives have arrived from three highly respected American firms and exclusively those with prior experience not with aircraft engines, but within industrial steam turbine design: Allis-Chalmers, Westinghouse, and the General Electric Steam Turbine Division at Schenectady. Intriguing fact, isn’t it?

The rationale for excluding the engine-producing companies from membership on the committee was not that they were too over-burdened with war-related work, because the steam turbine manufacturers were in the same situation. The selection of steam turbine manufacturers actually confirmed the theoretical choice of the axial-flow compressor with multiple stages, a compressor used in industrial steam turbines, as an completely appropriative solution.

If the engine companies had been included, they would have been more likely favor a design with a centrifugal compressor because of their previous experience with piston-engines superchargers.

Forced brak of the post... To be continued.

Librarian

04-17-2007, 07:34 PM

The case of Allis-Chalmers is highly intriguing in this specific issue. You see, as stated by Mr. George Lewis, the member of the aforesaid Committee, and NACA's director of research as well, in his personal letter addressed to Mr. Durand, "their particular interest was the axial-flow compressor, which has been constructed at Langley Field". Mr. Lewis revealed also that the results of a joint investigation with General Electric would be made available. This was obviously a reference to the eight-stage axial-flow compressor, previously constructed by Mr. Eastman Jacobs and Mr. Eugene Wasielewski, and intended primarily as a supercharger. I know that it sounds completely incredibly, but all three of the companies actually selected axial-flow compressors, although they decided not to attempt as many stages as Mr. Wasilewski and Mr. Jacobs, or German engineers.

At this point, all the signs indicated that an axial compressor would be a significant component of any jet propulsion scheme, a presumption shaped by the influence of Mr.Jacobs and the knowledge of the publications of the British aerodynamicists, Griffith and Constant. Future engineering practice would vindicate this decision, since the axial compressor did eventually prevail over the centrifugal one.

Stunning point is also the fact that the Westinghouse design team actually have decided to use a Brown-Bovery axial compressor as pretext for their construction (BTW: Brown-Bowery is highly renowned producer of steam turbines!) as its model. In any case, the company was completely familiar with the axial configuration through experience with axial compressors in Navy surface vessels.

To make this long story short, my dear Mr. Pdf 27, Westinghouse started the development of a project (X19A) sponsored by the U.S. Navy, actually the first real-made, genuine, distinctively American born and bred jet engine, that was ready in November of 1941. It was designed by a team guided by Mr. R. P. Kroon.

http://i10.photobucket.com/albums/a137/Langnasen/WestinghouseYankee19B.jpg

Westinghouse-Yankee R 19

Could you believe this – that aforesaid contraption (BTW: outfitted with some pretty nice characteristics!) was equipped with an axial compressor! Sweet Jesus, Joseph and Mary! :shock:

http://i10.photobucket.com/albums/a137/Langnasen/WestinghouseYankee19B-2.jpg

Six-stage axial compressor of the Westinghouse-Yankee 19 (18000 RPM in 1941!)

This early design lead to the more powerful J30 – series turbojet with 11-stage axial flow compressor and two-stage axial flow turbine. By 1944, Westinghouse was working on three derivatives of its first axial engine, the 19A (19 inch diameter). The 19A's direct descendant, the 19XB, became the J30, and powered the McDonnell FH-1 Phantom. Another variant, Westinghouse J34-WE-34 powered the famous McDonnell F2H Banshee, while Westinghouse J34-WE-36/36 A was used by Douglas for their F3D Skynight. Finally it has to be mentioned that Westinghouse J34-WE-30 was used by Vought company to, this time for their model F6 Pirate.

Well, US Navy probably was some kind of a…quite technologically extravagant society.

On the other hand, several different series J30s were used in US Air Force experimental aircraft program during the 1948-1953 period too. A J34-WE-22, rated at 1360 kg thrust, powered the tiny McDonnell XF-85 "Goblin." The McDonnell XF-88A used two J34-WE-15 engines, each rated at 1430 kg thrust, while the XF-88B used two XJ34-WE-19s, each rated at 1475 kg thrust. Power for the Douglas X-3 "Stiletto" was provided by two XJ34-WE-17s of 1528 kg thrust each. The -15, -17, and -19 engines were fitted with an afterburner for additional thrust when needed.

Yes, my dear Mr. Pdf 27 – I know that the adoption of the Whittle-type engine was a result of a high-ranking transatlantic visit that was performed by genera Arnold, who visited Great Britain in the spring of 1941. He was so impressed with the almost immediate accessibility of the Whittle gas-turbine engine, that due to his exceptionally augmented vexation - caused by American unpreparedness ("I don't want ever again to have the United States caught the way we were this time!") he successfully arranged for General Electric to manufacture this engine in the United States.

And so, on 2. October 1942, the Bell P-59A Airacomet, powered by a General Electric I-A gas turbine engine, became the first American jet-propelled aircraft to fly.

The I-A produced so low thrust, however, that performance was almost disappointing. Despite later installation of a more powerful engine, the P-59A did not reach the production stage. The British successfully developed the Meteor, powered by a Rolls Royce W-2B gas turbine engine and used it in World War2, although its performance was modestly better than that of the P-59A. By 1944, General Electric had developed a much more powerful gas turbine engine, the I-40, which was used to power the Lockheed XP80A fighter, developed by a mastermind of Clarence L. (Kelly) Johnson in just 143 days.

Of course, that is another story too...

Perhaps this is the right place for an additional observation toward generally not so widely recognized achievements of late Mr. David Smith, connected with the development of the first British axial flow jet engine for aircraft propulsion.

Another brake... To be continued soon.

Librarian

04-17-2007, 07:57 PM

Although Mr. David Smith was a steam turbine design engineer (sic!) within Metropolitan Vickers, he and other engeneers at the company were aware of the possibilities of the axial flow turbojet engine.

Originally, the first British axial-flow aircraft gas turbine B10 (known as Betty) was to have been built by the RAE (Royal Aircraft Establishment) the engines compressor was based on test data from experimental compressor "Anne" built to a design by A.A. Griffith of the RAE and manufactured by Fraser and Chalmers. A senior scientist within the RAE, A. A. Griffith had published paper on gas turbine development as early as 1926, and together with Hayne Constant, also of the RAE, considered that the compressors of future gas turbines should be of the axial type; However, the RAE did not have the manufacturing or research capability to make this aerodynamically complex compressor work on a scale sufficient to power an aircraft.

In 1937 discussions took place between the RAE and Metropolitan Vickers chief engineer Dr. Karl Baumann who in turn appointed Dr. David Smith to lead the design, development and manufacturing team. Work started at the company the following year under an Air Ministry Contract.

The experimental non-flight engine B10 had proved successful, with a compression ratio of 2:1. As war broke out and the Trafford Park Factory became committed to war work and space was at a premium, B10 had set fire to the research facility so it was decided to extend a small overspeed test cell which had been built in some secrecy on land off Barton Dock Road at Urmston, Manchester, with a view to relocate all gas turbine research and development. For a brief period the salt mines in Wincham had been used for engine testing, however pollution and fog from the nearby industrial town of Northwich caused contamination of the compressor blading which effected performance tests so all efforts were concentrated at "Barton Test’".

The first flight engine F2 ("Freda") ran in a test cell during December 1942, by June 1943 an F2 engine of 1800 lb static thrust was altitude tested in the tail of a Lancaster bomber. The Lancaster, which operated from the RAE Farnborough became the topic of much local discussion as it flew over the Manchester area. Interestingly, the aircraft allocated by the ministry was the Lancaster prototype which proved to be most unreliable, much to the frustration of Dr. Smith and the Metrovic team.

The first aircraft to be powered by and axial flow turbojet was a Gloster F/9 40 Meteor aircraft, the flight took place at the RAE on the 13th November 1943.

Metrovic continued turbojet development, the last flight engine being the F9 Sapphire, the design of which was handed to Armstong Siddley when Metropolitan Vickers decided to opt out of aircraft gas turbines and concentrate manufacturing and development on Industrial and Marine steam and gas turbines.

The test cells at Barton were turned over to steam turbine reseach and development in the early 1960’s. Dr. Smith returned to steam turbine design, although in great secrecy he was asked to assist Rolls-Royce’s Dr. Stanley Hooker when Rolls-Royce engineers ran into aerodynamic problems when developing the compressor for the famous Rolls-Royce Avon gas turbine engine.

It is worth noting that Whittle-type engines powered all the first generation of postwar jet aircraft…

Oh no, my dear Mr. Pdf 27. The MiG 9 “Fargo ” (first flight: April 24, 1946) was powered by two RD-20 jet engines (Soviet derivative of a BMW 003 A), and both Jak-15 and Jak 17 used a single RD 10 jet engine (Soviet version of a Jumo 004). You know… Just for the record.

RR Derwent instead is to me further evidence that your thesis that the Jumo-004 wasn't too bad really does not hold water. It wasn't until engines like the Armstrong-Siddely Sapphire and RR Avon became available in the 1950s that axial flow engines gained widespread acceptance.

Don’t be so sure, my dear Mr. Pdf 27. Those unknown masterpieces of engeneering produced back there in USSR are still widely unknown. Yes, you are right – they were not applied, more precisely not initially, but highly original constructive bureaus leaded by Stechkin and Mikulin actually have designed some very intriguing designs in early fifties. Yes, I know - this is not directly connected with WW2, but… Perhaps that will be a theme for another thread.:)

…and the only reason that they are nowadays limited to a few applications like helicopter engines is simply due to ducting problems when stacking compressors, rather than issues of frontal area.

Really, my dear Mr. Pdf27? Excellent. Allow me than a tiny proposal: let’s make a tiny mathematical exercise deeply connected with some standard engineering tasks in aeronautic industry. Would you be so kind to make for me the Constant outer engine intake diameter calculation [Dmax] (given as the equivalent flat-plate area), separately for an axial-compressor equipped, as well as for centrifugal compressor equipped engine, outfitted with the following common parameters:
• Inlet Mach number: 0.70
• stagnation pressure: 101.4 kPA
• Inlet stagnation temperature: 300 K
• Pressure ratio: 21
• Isentropic efficiency of the compressor: 0.85
• Isentropic efficiency of the turbine: 0.85
• Mechanical transmission efficiency between the turbine and compressor: 0.97
• Combustion chamber pressure loss factor: 0.06
• Static thrust of the engine: 72 kN
• Engine airflow: 65 kg/s.

After that, please recalculate the parasite drag value of different engines, and compare gained numerical results. I am pretty sure right now that an axial compressor engine would allow higher drag-efficiency at lower frontal areas, so vital for a modern aircraft, of course, with some sacrifice to weight and length.

And don’t worry – some personal friends of mine will land you a hand in this lastly mentioned task. We will do that in complete congruence with the prescription and methodology prescribed in a Educational Manual EM 910 – "Elements of Aeronautics", by Francis Pope and Arthur S. Otis, United States Armed Forces Institute, Washington.

I really can't see how the degree of reaction would substantially affect the reheat stage. All it does is change the design of the final stator.

Indeed wery good and truly matter oriented observation, my dear Mr. Pdf 27. Well, I have to admit that I was able to find no more than one possibility. Accordingly to Dr. Fritz Dietzel ("Gasturbinen", Vogel Verlag, 1974, p. 251), the degree of reaction, as the numerical ratio of the static pressure change in the rotor to the static pressure change through the whole stage, would substantially affect the turbine and compressor blades upstreaming and thus the flow simmetricity within the rotor and stator blades, and as a consequence the constructive possibility for the employment of the identical constructive parts for the rotor and stator blades network. For example, the compressor stage with a degree of reaction of 0.5 would share the pressure rise about equally between the rotor and stator, so the application of standardized components in that case will be possible.

http://i10.photobucket.com/albums/a137/Langnasen/Dietzel.jpg

"Degree of reaction", Dietzel, p.251

Accordingly to Dietzel, the degree of reaction amounts constructive complexity, possibility for constructive parts standardization, and therefore the employment of strategically critical materials.

However, knowing intrinsic and constant German engineering tendency toward thermodynamic conversion effectivity, my personal conviction is that the German constructors actually have contemplated about one specific, truly brilliant and even today sadly neglected technological solution. Namely this one:

Now, look carefully, my dear Mr. Pdf 27. Do you see that pretty peculiar component marked with No. 10, and located within the rear part of the engine?

http://i10.photobucket.com/albums/a137/Langnasen/Mistery.jpg

Mysterious Possibility

You do? Excellent. Can you guess the gadget? A little tip – in this case the degree of reaction is extremely important!

In the meantime, as always – all the best!

Panzerknacker

04-17-2007, 08:04 PM

Well, in that case, my dear Mr. Pdf27 I think that we can pronounce the whole genuine early American jet-engine design activity as a completely erroneous waste of time and money, and also to enunciate that aforesaid crime was committed by a group of staggering engineering idiots misfortunately positioned in the high places.

He,he , that was a good one :D

Digger

04-18-2007, 06:04 AM

Goering under the instructions of the Fuhrer asked Messerschmitt on the 3rd November 1943 if the Me 262 could carry bombs.

Messerschmitt replied that the original plans envisaged the Me 262 could carry two 551lb or 1,102lb bombs. When questioned further by Goering about this Messerschmitt was forced to admit the design work for the bomb release mechanism and the bomb pylons had not even been started.

Under further pressure from Goering, M esserschmitt claimed the necessary work could be completed within two weeks, of course not mentioning to the Reichsmarschall there had never been any intention to build the Me 262 as a fighter bomber.

Another problem facing the entire programme at this time, was only one prototype(V4) was available for test flying.

On November 12 1943 Erhard Milch expressed his concerns. "The one thing that we are not yet entirely sure of the problem of whether the Me 262, with it's jet engines, is so foolproof that we can go ahead with production next year. Are we ready-not only from the viewpoint of development, but also from the viewpoint of actual production?"

Major Knemeyer pointed out to Milch the Messerschmitt facilities engaged in work on the new fighter were in chaos and had run into a bottleneck. At this stage development work on two very critical items for the Me 262 had not been completed-the ejector seat and pressurized cockpit.

All this is a clear indication the Me 262 programme was encountering major difficulties outside of the continuing problems with the Jumo engines and at this stage the aircraft was not ready for production priority.

As can be seen all development work on the Me 262 had been with the view of producing it as a fighter, not a fighter bomber or a pure bomber. There was never any intention of Messerschmitt or his designers to produce the Me 262 as a fighter bomber or bomber and the first time this concept interrupted their thinking was during the conversation with Goering and then it was immediately forgotten. Equally at this stage even Erhard Milch operated under the belief the Me 262 was purely intended for fighter production and for good reason. The Arado Ar 234 light reconnaissance bomber was under development and as this aircraft was intended for purely this role any thought of the Me 262 filling the very same role had never been an option and was actually seen as a waste of resources.

This was the state of play in November 1943.

In the next post I will talk about the 'Blitz Bomber.'

Regards digger.

Digger

04-18-2007, 07:23 AM

Two Me 262 prototypes, the V4 and the V6 were presented to Hitler for demonstration at Insterburg on November 26 1943.

An engine of the V4 suffered a flame out and with test pilot Gerd Lindner at the controls the V6 was demonstrated to the Fuhrer. And it was a suitably impressive performance. It was at this demonstration it has been repeatedly claimed if the Me 262 could carry bombs and when informed it could Hitler decreed from this point the Me 262 would be produced as a Blitzbomber.

This version of the Me 262 development is an absolute fabrication. Firstly based on the erroneous information supplied to Goering by Messerschmitt himself, the Fuhrer already knew the Me 262 could carry bombs.

A telegram dictated by Hitler to a Luftwaffe aide was delivered to Goering 5th December 1943. It read: The Fuhrer has called our attention once more to the tremendous importance of the production of jet propelled aircraft for employment as fighter bombers It is imperative that the Luftwaffe has a number of jet fighter bombers[/COLOR] ready for front commitment by the Spring of 1944. Any difficulties occasioned by labour and raw material shortages will be resolved by the exploitation of Luftwaffe resources until auch time as existing shortages can be made up. The Fuhrer feels that a delay of our jet fighter programme would be tantamount to irresponsible negligence. the Fuhrer has directed that bimonthly written reports be made to him concerning the programme of the Me 262 and the Ar 234."

From this telegram it can be seen Hitler envisaged the Me 262 as a fighter bomber.

Although Speer shortly thereafter awarded the Me 262 top production priority, development problems still plagued the aircraft and the main production plant for the Me 262 at Kottern was not even complete and in fact it would never produce a single jet fighter.

Critically 23 Me 262A-0 airframes were available in February 1944, but there were no complete engines! It was to be April 1944 before 16 of these airframes received engines and were delivered to the Luftwaffe for evaluation. So we can see up to April 1944 no fighter bombers had been produced and all deliveries were in fact fighters. The major bottleneck in the programme to this point were the jumo engines.

It was at the notorious April 1944 conference with Milch, Goering and Saur that Hitler exploded and said,"Not a single one of my orders has been obeyed."
Milch attempted to explain the Me 262 had been designed purely as a fighter. This was the beginning of the end for Milch.

The V10 prototype had been used in testing programmes to this stage, hardly an interference to the Me 262 fighter programme.

Into May and the Fuhrer was insistent the fighter bomber Me 262 take priority, but it was to be the June 7 conference between Hitler and Saur which would be claimed Hitler's demands interfered with the introduction of the Me 262 as a fighter. This was the notorious 'Fuhrer-Befhel' which demanded intial production of the Me 262 be limited to bombers. Fighter development would be allowed to continue and not until these tests were concluded would production of the fighter version be permitted and once this point had been reached there would be no reason why production would not be shared between the bomber and fighter versions.

So did the Fuhrer-Befhel delay the inroduction of the Me 262 as a fighter? The answer is no as the detail modifications to adapt the Me 262 as a fighter bomber(bomb fusing equipment, design and testing of pylon designs, etc) had been completed before the announcement of the Fuhrer-Befhel and these modifications were relatively simple and could be carried out on the production line without any delay to deliveries. With these modifications the Me262 began to be delivered for service evaluation.

The problem of deliveries of the Me 262 still lay in engine problems and as we have seen with the freezing of engine development in early June 1944 led to the first deliveries, a mere 28 aircraft in June and 59 in July. the highest monthly production was 117 in October and as there were a surplus of airframes it can be seen delivery of the Me 262 was governed by the availability of the still less than satisfactory Jumo engines.

When the Fuhrer-Befhel was cancelled in early November 1944 a total of 315 Me 262's had been delivered to the Luftwaffe, by December deliveries had reached 513 aircraft out of a planned total of 1,360 aircraft, a shortfall of 847 aircraft due to non delivery of Jumo 004 engines.

Regards digger.

QX AMT

04-19-2007, 01:01 AM

I havent read any of the prior posts yet here on this thread but I found that the Messerschmitt 262 is being copied and replicas are built. Here is the web site if you are interested http://www.stormbirds.com/project/index.html
The Messerschmitt 262 jet fighter plane built late in World War II in Germany is back in production - at Seattle's Paine Field. They use a modern jet engine instead of the flaky original and they've strengthened a few weak points, but other than that it's a copy of the original. Price tag: $2 million a copy.

Cojimar 1945

04-19-2007, 04:31 AM

The Gloster Meteor evidently entered service at around the same time as the Me 262. Regardless, by 1944 the allies had jet fighters themselves.

If the British were so brilliant why didn't they defeat Germany themselves? Doubtless, they had some advanced technology but as far as I can tell the UK did not win the war by itself. Why is this?

The German designs may have been flawed but the Germans had the satisfaction of knowing they were stronger than Britain and that surely counts for something.

Raven

04-19-2007, 07:35 AM

Umm... What's with the 3 posts?... Pointless posts at that.

Panzerknacker

04-19-2007, 10:24 AM

Post merged, Cojimar try to do not repeat that consecutive posting.

Into May and the Fuhrer was insistent the fighter bomber Me 262 take priority, but it was to be the June 7 conference between Hitler and Saur which would be claimed Hitler's demands interfered with the introduction of the Me 262 as a fighter. This was the notorious 'Fuhrer-Befhel' which demanded intial production of the Me 262 be limited to bombers. Fighter development would be allowed to continue and not until these tests were concluded would production of the fighter version be permitted and once this point had been reached there would be no reason why production would not be shared between the bomber and fighter versions.

So did the Fuhrer-Befhel delay the inroduction of the Me 262 as a fighter? The answer is no as the detail modifications to adapt the Me 262 as a fighter bomber(bomb fusing equipment, design and testing of pylon designs, etc) had been completed before the announcement of the Fuhrer-Befhel and these modifications were relatively simple and could be carried out on the production line without any delay to deliveries. With these modifications the Me262 began to be delivered for service evaluation.

The 25th of May Hitler gave the more damaging ( in my opinion) order, this dviated resources for the develpment of variant like the Me 262A-2/U2 , is true that it was not the only cause some delay was caused also by allied bombing in the BMW motorplants.

I havent read any of the prior posts yet here on this thread

Well, you should ¡¡

Digger

04-19-2007, 11:05 AM

As only one airframe, Werk number 110 484 was modified to serve as the prototype Me 262A-2a/U2, it could hardly be called a major diversion of resources.

The source of production problems suffered by the Me 262 through it's entire service life was the slow delivery of engines. The fact the engines were still imperfect when all development was frozen did not help matters, nor did Allied bombing.

Considering the difficulties faced by the Germans, it is remarkable the manufacturers were able to deliver any completed aircraft. In retrospect the Fuhrer Befhel is used as a convenient way of explaining away the more complex issues which clouded the career of the Me 262.

Hitler's demand for the Me 262 to be used as a fighter bomber was not as crazy as people believe. Quite simply existing Luftwaffe types were incapable of penetrating Allied defences and his belief a superfast bomber type was needed to reverse the situation was not wide of the mark. In the end the German aero industry for a variety of reasons was not able to comply with his demands.

Regards digger.

pdf27

04-19-2007, 01:47 PM

Oh, please my dear Mr. Pdf27: this idiom is absolutely inappropriate for an Officer and a Gentlemen.
I make no claim to being either at this point in time.

Would you be so kind to present the resources, my dear Mr. Pdf27? You see, I was able to find the officially distributed information that J33 jet-engine, for example, demonstrated a median life of only 151 hours before general overhaul due to poor stress-rupture properties.
The RR Welland was rated at 180 hours between overhauls in 1943. That's a RATED value, i.e. one at which engine failure is highly unlikely before. See linky (http://en.wikipedia.org/wiki/Rolls-Royce_Welland). I can't however find the original source I was basing the 1,000 hours comment on.

Well, in that case, my dear Mr. Pdf27 I think that we can pronounce the whole genuine early American jet-engine design activity as a completely erroneous waste of time and money, and also to enunciate that aforesaid crime was committed by a group of staggering engineering idiots misfortunately positioned in the high places.
Pretty much, and that's what is so odd about it - the US organisation of industry in WW2 was nothing short of brilliant. However, when it came to jets they did very badly indeed. The US jet programme contributed precisely nothing to the allied war effort.

Personally, I think that part of the answer was already elucidated by a renowned N.A. Cumpsty, Head of the Whittle Laboratory, who has pointed out that the centrifugal compressor was used by Mr. Whittle because of the known difficulty of making an axial compressor. With a centrifugal compressor the use of the knowledge connected with pumps was obtainable, and - unlike the axial compressor (deeply connected with steam turbines!) - substantial pressure rise was producible, no matter how badly the aerodynamic of a design actually was calculated.
Precisely. Whittle got his engine to work in time for useful war service. The US concentration on axial flow engines produced nothing of value.
AA Griffith at the RAE was also trying to get British research to concentrate on axial flow designs for the same reason. He was wrong too.
Incidentally, I've spent a great deal of time at the Whittle Lab, and while I was there my supervisor was Professor John Denton, then head of the Lab. Nick Cumpsty was a Fellow at my college, but left to work at Rolls and became an Emeritus Fellow shortly before I matriculated.

Flow exit's a centrifugal compressor radially (at 90° to the flight direction) and it must therefore be redirected back towards the combustion chamber, resulting in a additional drop in thermodynamic efficiency.
So what? They were trying to get a working engine in wartime service. Who gives a stuff about isentropic efficiency so long as it works reliably and performs better than anything else you have? A bad jet engine is light years better than none at all, which is what the US ended up with.

It seems also that Mr. Whittle’s choice of a centrifugal compressor for the WU (Whittle Unit) actually was influenced by his previous association with BTH (British Thompson Houston) of Rugby, who actually built WU, as BTH were in a position to assist with compressor design data.
Again, demonstration that he had something between his ears. There was a huge amount of radial compressor design detail available, from superchargers and the like. There was naff all about axial compressors in comparison. Remember, the overwhelming priority was to get an engine in service as fast as possible.

And so, in the same month when the US Special Committee on Jet Propulsion was formed, engineering representatives have arrived from three highly respected American firms and exclusively those with prior experience not with aircraft engines, but within industrial steam turbine design: Allis-Chalmers, Westinghouse, and the General Electric Steam Turbine Division at Schenectady. Intriguing fact, isn’t it?
If not terribly bright. If they understand steam turbines, that means all they understand are axial turbines. A very different beast from axial compressors. It also means they will not use radial compressors, as they simply don't understand them.

The rationale for excluding the engine-producing companies from membership on the committee was not that they were too over-burdened with war-related work, because the steam turbine manufacturers were in the same situation. The selection of steam turbine manufacturers actually confirmed the theoretical choice of the axial-flow compressor with multiple stages, a compressor used in industrial steam turbines, as an completely appropriative solution.
No, it didn't - you're making a massive logical error here. It confirmed that they were going to use an axial flow compressor, whether it was appropriate or not. An aero engine company would have compared the two - a steam turbine company would not.

If the engine companies had been included, they would have been more likely favor a design with a centrifugal compressor because of their previous experience with piston-engines superchargers.
Indeed. And as Whittle demonstrated, that would have been absolutely the right choice in wartime conditions.

pdf27

04-19-2007, 02:04 PM

Future engineering practice would vindicate this decision, since the axial compressor did eventually prevail over the centrifugal one.
Again, BS. Just because future engineering practice would be one thing, does not mean another was not the appropriate solution at the time. Centimetric wave radar is nowadays used for early warning, but during WW2 longwave radar was used instead despite the availability of centimetric radar. Not because the people during WW2 were stupid or made the wrong decision, but because they couldn't yet build suitable centimetric sets. It was around 1950 before suitable axial flow compressors could be built.

Could you believe this – that aforesaid contraption (BTW: outfitted with some pretty nice characteristics!) was equipped with an axial compressor! Sweet Jesus, Joseph and Mary! :shock:
Yeah, what were they playing at. So, given just how "pretty nice" these characteristics were, exactly how many US combat aircraft flew in WW2 service powered by this miraculous engine?

This early design lead to the more powerful J30 – series turbojet with 11-stage axial flow compressor and two-stage axial flow turbine. By 1944, Westinghouse was working on three derivatives of its first axial engine, the 19A (19 inch diameter). The 19A's direct descendant, the 19XB, became the J30, and powered the McDonnell FH-1 Phantom. Another variant, Westinghouse J34-WE-34 powered the famous McDonnell F2H Banshee, while Westinghouse J34-WE-36/36 A was used by Douglas for their F3D Skynight. Finally it has to be mentioned that Westinghouse J34-WE-30 was used by Vought company to, this time for their model F6 Pirate.
Again, how many aircraft powered by this engine served in combat in WW2? That is the only yardstick that matters here. We were fighting a total war, from which only one side would survive. Any industrial effort diverted from winning that war (before the very end when it was plain we couldn't lose) was industrial effort working for the Axis.

The I-A produced so low thrust, however, that performance was almost disappointing. Despite later installation of a more powerful engine, the P-59A did not reach the production stage. The British successfully developed the Meteor, powered by a Rolls Royce W-2B gas turbine engine and used it in World War2, although its performance was modestly better than that of the P-59A.
Again, BS.

P-59:
Maximum speed: 413 mph (664 km/h)
Range: 240 mi (386 km)
Service ceiling: 46,200 ft (14,080 m)
Rate of climb: 3,200 ft/min (16,26 m/s)

Gloster Meteor F.8
Maximum speed: Mach 0.82, 600 mph at 10,000 ft (965 km/h at 3,050 m)
Range: 600 mi (965 km)
Service ceiling: 43,000 ft (13,100 m)
Rate of climb: 7,000 ft/min (35.6 m/s)

The F.8 is a postwar, cleaned-up version of the wartime Mark III, but finding plausible performance data for the Mark III is proving rather hard. The only valid data I can dig up and be confident in is the comparative evaluation that it was superior to the Tempest V in all departments except the heavy ailerons.

pdf27

04-19-2007, 02:29 PM

Really, my dear Mr. Pdf27? Excellent. Allow me than a tiny proposal: let’s make a tiny mathematical exercise deeply connected with some standard engineering tasks in aeronautic industry. Would you be so kind to make for me the Constant outer engine intake diameter calculation [Dmax] (given as the equivalent flat-plate area), separately for an axial-compressor equipped, as well as for centrifugal compressor equipped engine, outfitted with the following common parameters:
• Inlet Mach number: 0.70
• stagnation pressure: 101.4 kPA
• Inlet stagnation temperature: 300 K
• Pressure ratio: 21
• Isentropic efficiency of the compressor: 0.85
• Isentropic efficiency of the turbine: 0.85
• Mechanical transmission efficiency between the turbine and compressor: 0.97
• Combustion chamber pressure loss factor: 0.06
• Static thrust of the engine: 72 kN
• Engine airflow: 65 kg/s.
Trivially easy, and the two will be the same in any case. Incidentally, the only values you need in there are the inlet Mach number, inlet stagnation pressure & temperature and engine air flow. The rest is irrelevant, and looks suspiciously like you cut and pasted it out of a random textbook - it is not at all relevant to any part of your question, so it makes no sense to include it if you actually understood what you were talking about.
Neglecting edge effects, a diameter of 53.8cm should give you the required mass flux.

After that, please recalculate the parasite drag value of different engines, and compare gained numerical results. I am pretty sure right now that an axial compressor engine would allow higher drag-efficiency at lower frontal areas, so vital for a modern aircraft, of course, with some sacrifice to weight and length.
Can't be done - you need detailed compressor design details to get the frontal area of a centrifugal compressor from that data. With the data there, you don't have a chance. Parasitic drag will in any case be pretty low in either case - in a reasonably well streamlined nacelle, the only difference will be in the slightly increased wetted area. Wave drag is another matter however, and M=0.7 is fast enough you may have to worry about that. It is far more relevant to other parts of aerodynamics, however.

And don’t worry – some personal friends of mine will land you a hand in this lastly mentioned task. We will do that in complete congruence with the prescription and methodology prescribed in a Educational Manual EM 910 – "Elements of Aeronautics", by Francis Pope and Arthur S. Otis, United States Armed Forces Institute, Washington.
Which I suspect you are probably quoting here. Me, I personally prefer to go by what I was taught by lecturers like the aformentioned Prof. Cumpsty rather than the books they wrote. You tend to actually learn something that way.
Besides, why would I need help working out the air inlet area for something that simple? That's a back of a fag packet calculation at worst.

Indeed wery good and truly matter oriented observation, my dear Mr. Pdf 27. Well, I have to admit that I was able to find no more than one possibility. Accordingly to Dr. Fritz Dietzel ("Gasturbinen", Vogel Verlag, 1974, p. 251), the degree of reaction, as the numerical ratio of the static pressure change in the rotor to the static pressure change through the whole stage, would substantially affect the turbine and compressor blades upstreaming and thus the flow simmetricity within the rotor and stator blades, and as a consequence the constructive possibility for the employment of the identical constructive parts for the rotor and stator blades network. For example, the compressor stage with a degree of reaction of 0.5 would share the pressure rise about equally between the rotor and stator, so the application of standardized components in that case will be possible.
All well and good (well, sort of - the fact that you can't use common components anyway because the rotor and stator blades have to face in different directions seems to have passed you by!) but what's that got to do with afterburner/reheat?

Accordingly to Dietzel, the degree of reaction amounts constructive complexity, possibility for constructive parts standardization, and therefore the employment of strategically critical materials.
Last bit doesn't follow - it will use less material if they aren't standardised, as the stator blades can be made weaker and thus lighter, not having to withstand the rotational stresses imposed.

You do? Excellent. Can you guess the gadget? A little tip – in this case the degree of reaction is extremely important!
So far as I can tell from rather a bad drawing without accompanying text, that's a reverse flow heat exchanger such as fitted to the WR-21 marine gas turbine. Certainly you have the gas prior to the combustion chamber going one way through it, and that after the final turbine stage going the other way through it. I will admit however to being stunned if that is what it is, as nobody in their right mind would think to put one on an aero engine - it will be massively too complex, heavy and expensive for any fuel savings you make.

Panzerknacker

04-19-2007, 08:02 PM

As only one airframe, Werk number 110 484 was modified to serve as the prototype Me 262A-2a/U2, it could hardly be called a major diversion of resources.

The source of production problems suffered by the Me 262 through it's entire service life was the slow delivery of engines. The fact the engines were still imperfect when all development was frozen did not help matters, nor did Allied bombing

I did not object that the engines had its troubles but the bombings on Regensburg did not help either.

More on the Hitler s order on May.

http://img118.imageshack.us/img118/7569/dibujook2.jpg

The bomber mania was so much that actually the first operative Me-262 were bombers ¡¡¡ and were used over France in July 1944 by the Kommando Schenk.

http://img246.imageshack.us/img246/9259/schenkaz8.jpg

And yet another crazy experiment, towed glide bomb attached to a Me-262A-2 (v10)

http://img118.imageshack.us/img118/7480/v10ys2.jpg

Cojimar 1945

04-20-2007, 11:38 PM

The British flew some jets during the war but it appears they did little. Some V1's were shot down by Meteors but I have never heard of any instances of them shooting down axis aircraft.

Cojimar 1945

04-20-2007, 11:47 PM

The axis were losing badly from late 1942 onwards. An allied victory would seem likely even earlier but certainly from late 1942 onwards the axis were losing badly. Why should Americans be so concerned about the war with their enemies in retreat by such an early date?

pdf27

04-21-2007, 05:13 AM

The British flew some jets during the war but it appears they did little. Some V1's were shot down by Meteors but I have never heard of any instances of them shooting down axis aircraft.
14 V-1s to be exact. After that they were mainly used to train USAAF crews in combating jet aircraft, since until spring 1945 they were absolutely forbidden from flying over German-held territory. By the time this restriction was relaxed and they went hunting for German jets, it was too late and the Luftwaffe had been pretty much totally destroyed.

Edit: They did destroy of the order of 40 German aircraft on the ground after this point however.

Firefly

04-26-2007, 09:34 PM

The German designs may have been flawed but the Germans had the satisfaction of knowing they were stronger than Britain and that surely counts for something.

Can you tell me in what way Germany was stronger than the UK? And before you answer, consider than Panzer Divisions are not a sole indicator of power.

Cojimar 1945

04-29-2007, 04:07 AM

More powerful in terms of population and industrial capacity. The strange thing is that Germany did not utilize its massive production capacity for the war until late in the conflict.

windrider

05-01-2007, 01:29 PM

REIMAHG Me 262 Production Site near Kahla (Codename "Lachs" - "Salmon")

One of the most remarkable advancements made by the German military in World War II was the production of turbine-jet aircraft. The most famous of these was the Messerschmitt Me 262, developed beginning in 1938 and fielded in 1944. A special production facility was started in 1944, for quicker assembly line manufacture. Due to the setup at the main Messerschmitt factories, fast assembly line production was not possible, and these sites were vulnerable to Allied bombing. Accordingly, a company called Flugzeugwerke Reichsmarschall Hermann Göring (REIMAHG for short) was formed as a subsidiary of the Gustloff Nazi industrial complex. REIMAHG eventually became concerned only with the Me 262, and its main production facility was located in an old porcelain sand mine in the Walpersberg Hill near Kahla (south of Jena) -- Codename "Lachs" ("Salmon").

The existing tunnels in the Walpersberg were enlarged and others were dug, and massive concrete bunkers were built outside these tunnels. Subparts were made and partially assembled in the tunnels, then moved outside to the concrete bunkers, where final assembly took place. The assembled jets were then moved to the top of the hill via a platform that moved along a railed ramp by a power winch. The top of the Walpersberg had been leveled off and concreted in a massive construction effort, to form a runway some 3300 feet long. This was not sufficient for an Me 262 to take off (even with the jet engines, take-off was actually fairly slow), so small rockets assisted take-off. The runway was also too short for the jets to land, so leaving the Walpersberg was an all-or-nothing proposition: there could be no emergency landings. The jets were flown from Kahla to a site some 130 kilometers away to be fitted with weapons and radios, and to undergo final testing.

REIMAHG only managed to produce some twenty-seven Me 262 jet fighters by the end of the war. The work was done mostly by foreign forced laborers, some 991 of whom died during their nine months at "Lachs." The U.S. Army took the site on 12 April 1945, and before turning Thüringen over to the Soviets in July, they removed enough parts to finish five Me 262s that were found on the production line. Surprisingly, the Kahla area had not been bombed. British Intelligence had photographed Me 262s at the site in March 1945, so the Allies were well aware of "Lachs." But Kahla was spared the fate of the V-2 works at Nordhausen, which suffered a devastating bombing attack only eight days before the American Army arrived. (In spite of this historical report, the REIMAHG-Kahla site today shows many depressions that look very much like bomb craters that can be seen at such sites as Normandy and the Obersalzberg, and many areas that appear to have undergone explosive upheaval, all in areas that were flat during the war. This situation is apparently the result of Soviet activity after the war.)

Beginning in 1947, the Soviets blew up the concrete bunkers and assembly buildings, and also the entrances to most of the tunnels, including destruction of the concrete runway on the hilltop. However, the concrete buildings had reinforced walls some 10 feet thick, so in many cases, the explosions only collapsed the roofs. REIMAHG-Kahla remains today one of the most extensive Third Reich ruins sites, with the walls and foundations of most of the concrete assembly and workshop buildings, some still supporting parts of their roofs. The site is not generallyopen to the public.

Picture caption:
Part of an aerial view of the site, taken by British photo-reconnaissance on 19 March 1945. The Walpersberg with its hilltop runway is at the top. A tiny Me 262 can be seen just at the top of the ramp, beside the runway. Various bunkers and assembly buildings can be seen along the cleared area at the bottom of the slope, to the right of the ramp bottom. The dark blotches on the runway, to the right of the ramp, were apparently an attempt at painted camouflage. (Combined Intelligence Objectives Sub-committee (CIOS) - Underground Factories in Central Germany, London, 1945)

Source: http://www.thirdreichruins.com/thuringen.htm