whatisinaname
Donor
A “What If” Messerschmitt had said “no” to both Goring and Hitler’s question “Can it carry bombs?” With the Me-262 being produced as a pure fighter not a bomber or a fighter-bomber, the Ar-234 being developed as the first jet bomber and reconnaissance aircraft.
I have had to “work around” various battles in 1944 and 1945 to “fit in” with this story and to extend WW2 into late 1945.
Enjoy.
Please Note - I will be adding to this TL infrequently.
Can it Carry Bombs?
1.
Me 262 Origins
In late 1938, a Messerschmitt design team under Dr. Waldermar Voight had drawn up concepts for an interceptor fighter with twin turbojet engines. The preliminary designs for “Project 1065”, as it was designated, went through an iteration or two and finally resulted in a proposal submitted to the RLM in May 1940.
Messerschmitt’s dream fighter had the turbojets mounted in nacelles under the middle of the wings. The wings were slightly swept to ensure proper centre of gravity, and had an unusually thin chord, or ratio of thickness to width, for good high-speed performance. As the wing’s features for high-speed performance compromised low-speed handling, a “slat” was added to the front of the outer wings, this slat was automatically extended to improve handling at low speeds.
The fuselage had a triangular cross section and substantial fuel capacity to feed the thirsty engines. The aircraft was a “tailsitter”, with fully retractable landing gear. In July 1940, the RLM ordered three prototypes, under the designation “Messerschmitt 262 or Me-262”, to be powered by BMW-003 engines.
Airframe development far outpaced engine development, and so the first prototype, the “Me-262-V1” (“V” standing for “Versuchs” or “Experimental”), was fitted with a single Jumo-210G piston engine with 710 horsepower and a two-bladed propeller for preliminary test flights. First flight was on the 18th April 1941. The RLM was becoming more interested in the aircraft, ordering five more prototypes in July 1941, to follow the initial order for three.
The Me-262-V1 was finally fitted with a pair of BMW-003 turbojets, each with 550 kilograms (1,200 pounds) thrust, in November 1941. The Jumo 210G piston engine was retained, which was fortunate, since the turbojet engines were hopelessly unreliable. On the 25th March 1942, Messerschmitt test pilot Fritz Wendel took off and suffered immediate failures of both engines. He managed to make a go-round on the piston engine and land, damaging the aircraft but suffering no injury himself.
Development of the BMW-003 engine was progressing slowly, while work on the Junkers Jumo-004 seemed more promising, and so the third prototype, the “Me-262-V3”, was fitted with two Jumo-004A pre-production engines with 840 kilograms (1,850 pounds) thrust each. Wendel took the V3 into the air on the 18th July 1942 and found the aircraft extremely impressive. Unfortunately, the V3 prototype was wrecked on its second test flight, three weeks later.
The Me-262V-2 prototype, also powered by Jumo-004As, was not delivered until 2nd October 1942. Despite all the delays and problems, the RLM had already ordered 15 pre-production Me-262s in May 1942, and added 30 more to the order in October 1942. The He-280 was clearly inferior in performance and the Me-262 was clearly the better option, but there was still no commitment to put the Me-262 into full production. RLM was waffling between committing to production of the Me-262 and the Me-209, an improved version of the piston-powered Messerschmitt Bf-109 fighter. The head of the RLM, Erhard Milch, was conservative and favoured the Me-209 over the much more radical Me-262.
First Steps
However, in the spring of 1943 the tide began to shift towards the jet fighter. The Luftwaffe’s General of Fighters, Adolf Galland, flew the recently delivered “V4” prototype on the 22nd May 1943. He enthusiastically endorsed the type and suggested that the Me-209 be cancelled. A few days later, the RLM placed an order for 100 production Me-262s.
Apparently even this decision did not clear away all the bureaucratic obstacles, Willi Messerschmitt himself was also causing problems, because he kept on lobbying to produce both the Me-209 and the Me-262, partly this seems to be a ploy in bureaucratic empire-building, and it wasn’t until November 1943 that the Me-209 was dropped for good.
Even then, the Me-262’s political troubles were far from over, and in fact were just about to take a very odd turn. Hitler, alarmed by the success of Allied amphibious landings in Africa and Italy, was very concerned about developing a fast fighter-bomber (“Jagdbomber” or “Jabo”) to pin down invasion forces on the beaches until reinforcements could arrive to drive them back into the sea.
On the 2nd November 1943, Reichsmarshall Hermann Goring, head of the Luftwaffe, and Milch visited the Messerschmitt plant in Augsburg. Goring asked Willi Messerschmitt if the new jet fighter could carry bombs. Messerschmitt answered without hesitation that the Me-262 could not carry bombs and a lot of work would need to be done to make the Me-262 in a “Jabo”. Willi Messerschmitt goes on to state that the Me-262 was designed from the onset to destroy enemy bomber and fighters Goring seemed satisfied with Messerschmitt’s answer.
Hitler’s Order, November 1943
On the 26th November 1943, Hitler inspected the Me-262 at Insterburg, and asked the same question “Can it carry bombs?” Messerschmitt gave him the same answer that he had given Goring. Hitler seemed satisfied with Messerschmitt’s answer and ordered that the Me-262 to be built as a fighter to destroy bombers, and the Ar-234 to be built primarily as a bomber with a limited number going to the reconnaissance role, both would be for use against the possible allied landings that would take place in France, in 1944. There is little record of anyone contesting his decision, nonetheless, Messerschmitt completely agreed with the will of the Fuehrer about the Me-262 and busily worked to put the machine into production as a fighter.
Milch, on reading intelligence reports that the Americans were getting ready to field new bombers such as the Boeing B-29 that would be a handful for existing interceptors, also pressed on with production of the Me-262 as a fighter, ignoring the Ar-234 needs at the same level of priority. Though Milch made agreeable noises about building Ar-234, little or nothing was done to make the Ar-234 as a bomber, though work was commencing to use the Ar-234 in the reconnaissance role.
Things would be set to come to head with Hitler in May of 1944, as Hitler had assumed that the Me-262 and Ar-234 were at the same levels of development and priority, but Hitler was wrong, no one had thought to inform Hitler that the Ar-234 was well behind the Me-262 in development. Hitler was pinning his hopes on the Ar-234 to hold the Allied invasion on the beaches until the German Army arrived to drive the allies into the sea.
Hitler’s decision regarding the Me-262 would have long term consequences for the defence of German airspace in late 1944 and early 1945, this decision would also have a significant influence on the outcome of the war, in a most unusual way regarding Hitler’s military decisions on all the front that the various forms that these two types of Jets would serve.
Me-262 into Production!
Whatever the political issues surrounding the Me-262 program, the real difficulty was that the aircraft was still a long way from being able to be built in any significant numbers. At the time (early 1943), there was only one Me-262 flying, the “V4” prototype. The previous three prototypes had been wrecked one way or another, and the “V5” prototype was being rebuilt to use tricycle landing gear, at the suggestion of Adolf Galland. Given the aircraft’s long nose, the “tailsitter” landing gear configuration made forward visibility on the ground extremely poor, and the downward-pointing jets also tore up the ground.
The V5 had a fixed nose wheel, but was followed by the “V6” in October 1943, which had fully retractable landing gear and was close to production specification, and then the last test prototype, the “V7”.
By April 1943, 13 pre-production “Me-262A0s” had been completed of an ultimate total of 45 built, out of the initial 45 ordered, though the pre-production “Me-262A0s” would continue to be produced until the production Me-262A1as were available in May 1944. These aircraft were close to production specification, but some had specialized test fits. For example, the “V12” was modified as a high-speed test article with a smaller canopy and other changes, and was clocked at 1,005 kph (624 mph), substantially faster than a standard Me-262.
Some of the pre-production machines (Me-262A0s) where being sent on to the Luftwaffe for operational evaluation by a group organized in February 1944 for the task, designated “Erprobungskommando (Proving Detachment) 262”. It seemed like the Me-262 was coming into service at precisely the right of time, since now the US Army Air Force (USAAF) had adequate numbers of long-range P-51D Mustang fighters to escort bombers on daylight raids over Germany, greatly complicating the air defence of the Reich. The Me-262 might well tilt the balance back to the defenders if enough of them could be produced.
That was also easier said than done, Messerschmitt was straining to keep up with demands for production of existing aircraft types, a difficulty compounded by a devastating Allied air raid on the company’s plant at Regensburg on the 17th August 1943. Production had to be relocated to Oberammergau, near the Bavarian Alps. Delivering the temperamental Jumo-004 turbojets was even more troublesome.
In early January 1944 it was decided to keep the Me-262A0 limited production line (what would be referred to as initial low rate production today) running until full production of the Me-262A1a variant could enter production, this order proved to be very useful, as it allowed Erprobungskommando 262 to achieve full operational strength by February 1944. This limited production run of Me-262A0 would only be able to produce limited numbers of Me-262A0’s, but even these limited numbers would allow Erprobungskommando 262 throughout the first three months of 1944 to set-up a crude training program for the Me-262.
The production rate of the Me-262A0’s is very low, with only 5 aircraft being delivered every week (seven days), the Erprobungskommando 262 would take a while to set-up at this rate of delivery, but with the Me-262A1a due to enter full scale production in March 1944 (this was delayed by the bombing raid on Regensburg), the limited numbers being produced was not seen as a problem, as these aircraft would be used to train or re-train pilots until full production of the Me-262A1a was up and running.
Jet Engines
The initial 004A engines built to power the Me-262 prototypes had been built without restrictions on materials, and they used scarce raw materials such as nickel, cobalt, and molybdenum in quantities, which were unacceptable in production. Franz realized that the Jumo 004 would have to be redesigned to incorporate a minimum of these strategic materials, and this was accomplished.
All the hot metal parts including the combustion chamber were changed to mild steel protected by an aluminium coating, and the hollow turbine blades were produced from folded and welded Cromadur alloy (12% chromium, 18% manganese, and 70% iron) developed by Krupp, and cooled by compressed air “bled” from the compressor. The engine’s operational lifespan was shortened, but on the plus side it became easier to construct.
The first production model of the 004B weighed 220 lb (100 kg) less than the 004A, and in 1943 had passed several 100-hour tests, with a time between overhauls of 50 hours being achieved.
Later in 1943 a series of engines suffered vibration problems, and solutions dragged on. Eventually, in December, blade-vibration specialist Max Bentele was once again brought in during a meeting at the RLM headquarters, and the problem was solved by raising the blades’ natural frequency by increasing their taper, shortening them by 1 millimetre, and reducing the operating speed of the engine from 9,000 to 8,700 rpm.
It was not until early 1944 that full production of the 004B could finally begin in the interim the 004A would be used for the Me-262-A0’s in various operation test and training units that would be set-up in early 1944. These setbacks were the principal factor delaying the Luftwaffe’s introduction of the Me-262 into full squadron service.
Given the lower-quality steels used in the 004B, these engines typically only had a service life of some 10-25 hours, perhaps twice this in the hands of a skilled pilot. Another shortcoming of the engine, common to all early turbojets, was its sluggish throttle response. Worse, it was fairly easy to inject too much fuel into the engine by throttling up too quickly, allowing heat to build up before the cooling air could remove it. This led to softening of the turbine blades, and was a major cause for engine failures. Nevertheless, it made jet power for combat aircraft a reality for the first time.
The exhaust area of the 004 featured a variable geometry nozzle, which had a special restrictive body nicknamed the Zwiebel (German for onion, due to its shape when seen from the side) which had roughly 40 cm (16 inch) fore-and-aft travel to vary the jet exhaust's cross-sectional area for thrust control, as the active part of a pioneering “divergent-convergent” nozzle format.
One interesting feature of the 004 was the starter system, which consisted of a Riedel 10 hp (7 kW) 2-stroke motorcycle engine hidden in the intake. A hole in the extreme nose of the centre body contained a pull-handle, which started the piston engine, which in turn spun up the turbine. Two small gasoline tanks were fitted in the annular intake.
The Jumo 004 could run on three types of fuel:-
1. J-2, its standard fuel, a synthetic fuel produced from coal.
2. Diesel oil.
3. Aviation gasoline; not considered desirable due to its high rate of consumption.
All Jets would use the J-2 fuel, as this type of fuel was more readily available than the other two types.
Armament
The armament of the Me-262 would consist of 4 30mm cannons mounted in the nose of the aircraft, the MK 108 (Maschinenkanone or Machine Cannon) was an 30 mm calibre autocannon manufactured by Rheinmetall-Borsig for use in a variety of aircraft. This weapon would become synonyms with the Me-262 for it killing power against all types of allied aircraft.
The cannon used specially developed 30x90RB mm ammunition 30 mm calibre, 90 mm case length and rebated/reduced rim. Unlike most other weapon rounds, which used traditional brass for the case, the MK 108's ammunition used steel cases. Several types of ammunition were developed, including practice, armour piercing, high explosive and incendiary.
The cannon proved to be very effective and reliable, yet comparatively light, compact and easy to manufacture. These characteristics stem from its simple construction 80% of the weapon was made from stamped parts, and the number of moving parts was kept to a bare minimum using a simple blowback operation. However, the simple blowback operation had its disadvantages.
The low muzzle velocity needed for this simple operation became the MK 108's main shortcoming, with the result that its projectile trajectory was seriously affected by bullet drop after a comparatively short range, 41 meters of drop in the first 1000 meters of range. This made effective firing ranges very short and aiming a challenge, particularly with fast flying aircraft as the Me-262, though with four of these mounted in the nose, this meant that a one second burst from all four cannons would put just over forty rounds on a target at close range, this was normally enough to bring down or seriously damage any allied aircraft. This meant that the Me-262 had to get close before firing, with it superior speed that was not a problem, all that was need would be to train the pilots on the procedure, a unit called Kommando Schreiber would set the basic tactics for the Me-262, along with Kommando Nowotny in mid 1944.
Otherwise, it was simple to manufacture and maintain, and its compact size and weight as well as its electrical priming made it ideal for aircraft installation. The cannon's distinctive heavy pounding sound and high rate of fire gave it the nickname “pneumatic hammer” amongst Allied aircrews, amongst which the cannon gained a fearsome reputation due to its destructive power.
In operations however, two major ammunition types were used, Minengeschoß (“mine-shell”) high-explosive incendiary. The Minengeschoß was made by drawn steel (the same way brass cartridges are made) instead of being forged and machined, as was the usual practice for cannon shells. This resulted in a shell with a thin but strong wall, which hence had a much larger cavity in which to pack a much larger explosive or incendiary charge than was otherwise possible.
The incendiary rounds were also often fitted with a hydrostatic fuse, which detonated when it came in contact with liquid. This was to ensure that the round did not merely explode on the target aircraft’s skin (which would cause little damage), but instead penetrated it and exploded when it came into contact with fuel or coolant inside the fuel tanks or radiators respectively.
Ar-234
Meanwhile the other Jet about to enter production was the Ar-234, the Ar-234 development was also progressing, but the Ar-234 development was many months behind that of the Me-262. The Ar-234 was not even entering pre-production at the same time, as Hitler has assumed, but events in early 1944 would lead Hitler to assume that the Ar-234 was entering full-scale production, just slightly behind that of the Me-262.
The Ar-234 would also be fitted with the Junkers Jumo 004B-1 turbojets like the Me-262, this would cause a shortage of engines for both aircraft, and this problem of supplying of the Junkers Jumo 004B-1 turbojets would not be solved until early 1945, by fitting the Ar-234 with four BMW 003A engines.
As 1943 came to a close, Germany was on the verge of introducing a very high performance fighter (Me-262), but with a large number of technical problems still existing, most of which were to do with the engines. This would not be an easy “birth” for the Me262, or even the Ar-234.
What would 1944 bring for the Me-262 and the Ar-234?
To be continued, if there is any interest in this TL?
I have had to “work around” various battles in 1944 and 1945 to “fit in” with this story and to extend WW2 into late 1945.
Enjoy.
Please Note - I will be adding to this TL infrequently.
Can it Carry Bombs?
1.
Me 262 Origins
In late 1938, a Messerschmitt design team under Dr. Waldermar Voight had drawn up concepts for an interceptor fighter with twin turbojet engines. The preliminary designs for “Project 1065”, as it was designated, went through an iteration or two and finally resulted in a proposal submitted to the RLM in May 1940.
Messerschmitt’s dream fighter had the turbojets mounted in nacelles under the middle of the wings. The wings were slightly swept to ensure proper centre of gravity, and had an unusually thin chord, or ratio of thickness to width, for good high-speed performance. As the wing’s features for high-speed performance compromised low-speed handling, a “slat” was added to the front of the outer wings, this slat was automatically extended to improve handling at low speeds.
The fuselage had a triangular cross section and substantial fuel capacity to feed the thirsty engines. The aircraft was a “tailsitter”, with fully retractable landing gear. In July 1940, the RLM ordered three prototypes, under the designation “Messerschmitt 262 or Me-262”, to be powered by BMW-003 engines.
Airframe development far outpaced engine development, and so the first prototype, the “Me-262-V1” (“V” standing for “Versuchs” or “Experimental”), was fitted with a single Jumo-210G piston engine with 710 horsepower and a two-bladed propeller for preliminary test flights. First flight was on the 18th April 1941. The RLM was becoming more interested in the aircraft, ordering five more prototypes in July 1941, to follow the initial order for three.
The Me-262-V1 was finally fitted with a pair of BMW-003 turbojets, each with 550 kilograms (1,200 pounds) thrust, in November 1941. The Jumo 210G piston engine was retained, which was fortunate, since the turbojet engines were hopelessly unreliable. On the 25th March 1942, Messerschmitt test pilot Fritz Wendel took off and suffered immediate failures of both engines. He managed to make a go-round on the piston engine and land, damaging the aircraft but suffering no injury himself.
Development of the BMW-003 engine was progressing slowly, while work on the Junkers Jumo-004 seemed more promising, and so the third prototype, the “Me-262-V3”, was fitted with two Jumo-004A pre-production engines with 840 kilograms (1,850 pounds) thrust each. Wendel took the V3 into the air on the 18th July 1942 and found the aircraft extremely impressive. Unfortunately, the V3 prototype was wrecked on its second test flight, three weeks later.
The Me-262V-2 prototype, also powered by Jumo-004As, was not delivered until 2nd October 1942. Despite all the delays and problems, the RLM had already ordered 15 pre-production Me-262s in May 1942, and added 30 more to the order in October 1942. The He-280 was clearly inferior in performance and the Me-262 was clearly the better option, but there was still no commitment to put the Me-262 into full production. RLM was waffling between committing to production of the Me-262 and the Me-209, an improved version of the piston-powered Messerschmitt Bf-109 fighter. The head of the RLM, Erhard Milch, was conservative and favoured the Me-209 over the much more radical Me-262.
First Steps
However, in the spring of 1943 the tide began to shift towards the jet fighter. The Luftwaffe’s General of Fighters, Adolf Galland, flew the recently delivered “V4” prototype on the 22nd May 1943. He enthusiastically endorsed the type and suggested that the Me-209 be cancelled. A few days later, the RLM placed an order for 100 production Me-262s.
Apparently even this decision did not clear away all the bureaucratic obstacles, Willi Messerschmitt himself was also causing problems, because he kept on lobbying to produce both the Me-209 and the Me-262, partly this seems to be a ploy in bureaucratic empire-building, and it wasn’t until November 1943 that the Me-209 was dropped for good.
Even then, the Me-262’s political troubles were far from over, and in fact were just about to take a very odd turn. Hitler, alarmed by the success of Allied amphibious landings in Africa and Italy, was very concerned about developing a fast fighter-bomber (“Jagdbomber” or “Jabo”) to pin down invasion forces on the beaches until reinforcements could arrive to drive them back into the sea.
On the 2nd November 1943, Reichsmarshall Hermann Goring, head of the Luftwaffe, and Milch visited the Messerschmitt plant in Augsburg. Goring asked Willi Messerschmitt if the new jet fighter could carry bombs. Messerschmitt answered without hesitation that the Me-262 could not carry bombs and a lot of work would need to be done to make the Me-262 in a “Jabo”. Willi Messerschmitt goes on to state that the Me-262 was designed from the onset to destroy enemy bomber and fighters Goring seemed satisfied with Messerschmitt’s answer.
Hitler’s Order, November 1943
On the 26th November 1943, Hitler inspected the Me-262 at Insterburg, and asked the same question “Can it carry bombs?” Messerschmitt gave him the same answer that he had given Goring. Hitler seemed satisfied with Messerschmitt’s answer and ordered that the Me-262 to be built as a fighter to destroy bombers, and the Ar-234 to be built primarily as a bomber with a limited number going to the reconnaissance role, both would be for use against the possible allied landings that would take place in France, in 1944. There is little record of anyone contesting his decision, nonetheless, Messerschmitt completely agreed with the will of the Fuehrer about the Me-262 and busily worked to put the machine into production as a fighter.
Milch, on reading intelligence reports that the Americans were getting ready to field new bombers such as the Boeing B-29 that would be a handful for existing interceptors, also pressed on with production of the Me-262 as a fighter, ignoring the Ar-234 needs at the same level of priority. Though Milch made agreeable noises about building Ar-234, little or nothing was done to make the Ar-234 as a bomber, though work was commencing to use the Ar-234 in the reconnaissance role.
Things would be set to come to head with Hitler in May of 1944, as Hitler had assumed that the Me-262 and Ar-234 were at the same levels of development and priority, but Hitler was wrong, no one had thought to inform Hitler that the Ar-234 was well behind the Me-262 in development. Hitler was pinning his hopes on the Ar-234 to hold the Allied invasion on the beaches until the German Army arrived to drive the allies into the sea.
Hitler’s decision regarding the Me-262 would have long term consequences for the defence of German airspace in late 1944 and early 1945, this decision would also have a significant influence on the outcome of the war, in a most unusual way regarding Hitler’s military decisions on all the front that the various forms that these two types of Jets would serve.
Me-262 into Production!
Whatever the political issues surrounding the Me-262 program, the real difficulty was that the aircraft was still a long way from being able to be built in any significant numbers. At the time (early 1943), there was only one Me-262 flying, the “V4” prototype. The previous three prototypes had been wrecked one way or another, and the “V5” prototype was being rebuilt to use tricycle landing gear, at the suggestion of Adolf Galland. Given the aircraft’s long nose, the “tailsitter” landing gear configuration made forward visibility on the ground extremely poor, and the downward-pointing jets also tore up the ground.
The V5 had a fixed nose wheel, but was followed by the “V6” in October 1943, which had fully retractable landing gear and was close to production specification, and then the last test prototype, the “V7”.
By April 1943, 13 pre-production “Me-262A0s” had been completed of an ultimate total of 45 built, out of the initial 45 ordered, though the pre-production “Me-262A0s” would continue to be produced until the production Me-262A1as were available in May 1944. These aircraft were close to production specification, but some had specialized test fits. For example, the “V12” was modified as a high-speed test article with a smaller canopy and other changes, and was clocked at 1,005 kph (624 mph), substantially faster than a standard Me-262.
Some of the pre-production machines (Me-262A0s) where being sent on to the Luftwaffe for operational evaluation by a group organized in February 1944 for the task, designated “Erprobungskommando (Proving Detachment) 262”. It seemed like the Me-262 was coming into service at precisely the right of time, since now the US Army Air Force (USAAF) had adequate numbers of long-range P-51D Mustang fighters to escort bombers on daylight raids over Germany, greatly complicating the air defence of the Reich. The Me-262 might well tilt the balance back to the defenders if enough of them could be produced.
That was also easier said than done, Messerschmitt was straining to keep up with demands for production of existing aircraft types, a difficulty compounded by a devastating Allied air raid on the company’s plant at Regensburg on the 17th August 1943. Production had to be relocated to Oberammergau, near the Bavarian Alps. Delivering the temperamental Jumo-004 turbojets was even more troublesome.
In early January 1944 it was decided to keep the Me-262A0 limited production line (what would be referred to as initial low rate production today) running until full production of the Me-262A1a variant could enter production, this order proved to be very useful, as it allowed Erprobungskommando 262 to achieve full operational strength by February 1944. This limited production run of Me-262A0 would only be able to produce limited numbers of Me-262A0’s, but even these limited numbers would allow Erprobungskommando 262 throughout the first three months of 1944 to set-up a crude training program for the Me-262.
The production rate of the Me-262A0’s is very low, with only 5 aircraft being delivered every week (seven days), the Erprobungskommando 262 would take a while to set-up at this rate of delivery, but with the Me-262A1a due to enter full scale production in March 1944 (this was delayed by the bombing raid on Regensburg), the limited numbers being produced was not seen as a problem, as these aircraft would be used to train or re-train pilots until full production of the Me-262A1a was up and running.
Jet Engines
The initial 004A engines built to power the Me-262 prototypes had been built without restrictions on materials, and they used scarce raw materials such as nickel, cobalt, and molybdenum in quantities, which were unacceptable in production. Franz realized that the Jumo 004 would have to be redesigned to incorporate a minimum of these strategic materials, and this was accomplished.
All the hot metal parts including the combustion chamber were changed to mild steel protected by an aluminium coating, and the hollow turbine blades were produced from folded and welded Cromadur alloy (12% chromium, 18% manganese, and 70% iron) developed by Krupp, and cooled by compressed air “bled” from the compressor. The engine’s operational lifespan was shortened, but on the plus side it became easier to construct.
The first production model of the 004B weighed 220 lb (100 kg) less than the 004A, and in 1943 had passed several 100-hour tests, with a time between overhauls of 50 hours being achieved.
Later in 1943 a series of engines suffered vibration problems, and solutions dragged on. Eventually, in December, blade-vibration specialist Max Bentele was once again brought in during a meeting at the RLM headquarters, and the problem was solved by raising the blades’ natural frequency by increasing their taper, shortening them by 1 millimetre, and reducing the operating speed of the engine from 9,000 to 8,700 rpm.
It was not until early 1944 that full production of the 004B could finally begin in the interim the 004A would be used for the Me-262-A0’s in various operation test and training units that would be set-up in early 1944. These setbacks were the principal factor delaying the Luftwaffe’s introduction of the Me-262 into full squadron service.
Given the lower-quality steels used in the 004B, these engines typically only had a service life of some 10-25 hours, perhaps twice this in the hands of a skilled pilot. Another shortcoming of the engine, common to all early turbojets, was its sluggish throttle response. Worse, it was fairly easy to inject too much fuel into the engine by throttling up too quickly, allowing heat to build up before the cooling air could remove it. This led to softening of the turbine blades, and was a major cause for engine failures. Nevertheless, it made jet power for combat aircraft a reality for the first time.
The exhaust area of the 004 featured a variable geometry nozzle, which had a special restrictive body nicknamed the Zwiebel (German for onion, due to its shape when seen from the side) which had roughly 40 cm (16 inch) fore-and-aft travel to vary the jet exhaust's cross-sectional area for thrust control, as the active part of a pioneering “divergent-convergent” nozzle format.
One interesting feature of the 004 was the starter system, which consisted of a Riedel 10 hp (7 kW) 2-stroke motorcycle engine hidden in the intake. A hole in the extreme nose of the centre body contained a pull-handle, which started the piston engine, which in turn spun up the turbine. Two small gasoline tanks were fitted in the annular intake.
The Jumo 004 could run on three types of fuel:-
1. J-2, its standard fuel, a synthetic fuel produced from coal.
2. Diesel oil.
3. Aviation gasoline; not considered desirable due to its high rate of consumption.
All Jets would use the J-2 fuel, as this type of fuel was more readily available than the other two types.
Armament
The armament of the Me-262 would consist of 4 30mm cannons mounted in the nose of the aircraft, the MK 108 (Maschinenkanone or Machine Cannon) was an 30 mm calibre autocannon manufactured by Rheinmetall-Borsig for use in a variety of aircraft. This weapon would become synonyms with the Me-262 for it killing power against all types of allied aircraft.
The cannon used specially developed 30x90RB mm ammunition 30 mm calibre, 90 mm case length and rebated/reduced rim. Unlike most other weapon rounds, which used traditional brass for the case, the MK 108's ammunition used steel cases. Several types of ammunition were developed, including practice, armour piercing, high explosive and incendiary.
The cannon proved to be very effective and reliable, yet comparatively light, compact and easy to manufacture. These characteristics stem from its simple construction 80% of the weapon was made from stamped parts, and the number of moving parts was kept to a bare minimum using a simple blowback operation. However, the simple blowback operation had its disadvantages.
The low muzzle velocity needed for this simple operation became the MK 108's main shortcoming, with the result that its projectile trajectory was seriously affected by bullet drop after a comparatively short range, 41 meters of drop in the first 1000 meters of range. This made effective firing ranges very short and aiming a challenge, particularly with fast flying aircraft as the Me-262, though with four of these mounted in the nose, this meant that a one second burst from all four cannons would put just over forty rounds on a target at close range, this was normally enough to bring down or seriously damage any allied aircraft. This meant that the Me-262 had to get close before firing, with it superior speed that was not a problem, all that was need would be to train the pilots on the procedure, a unit called Kommando Schreiber would set the basic tactics for the Me-262, along with Kommando Nowotny in mid 1944.
Otherwise, it was simple to manufacture and maintain, and its compact size and weight as well as its electrical priming made it ideal for aircraft installation. The cannon's distinctive heavy pounding sound and high rate of fire gave it the nickname “pneumatic hammer” amongst Allied aircrews, amongst which the cannon gained a fearsome reputation due to its destructive power.
In operations however, two major ammunition types were used, Minengeschoß (“mine-shell”) high-explosive incendiary. The Minengeschoß was made by drawn steel (the same way brass cartridges are made) instead of being forged and machined, as was the usual practice for cannon shells. This resulted in a shell with a thin but strong wall, which hence had a much larger cavity in which to pack a much larger explosive or incendiary charge than was otherwise possible.
The incendiary rounds were also often fitted with a hydrostatic fuse, which detonated when it came in contact with liquid. This was to ensure that the round did not merely explode on the target aircraft’s skin (which would cause little damage), but instead penetrated it and exploded when it came into contact with fuel or coolant inside the fuel tanks or radiators respectively.
Ar-234
Meanwhile the other Jet about to enter production was the Ar-234, the Ar-234 development was also progressing, but the Ar-234 development was many months behind that of the Me-262. The Ar-234 was not even entering pre-production at the same time, as Hitler has assumed, but events in early 1944 would lead Hitler to assume that the Ar-234 was entering full-scale production, just slightly behind that of the Me-262.
The Ar-234 would also be fitted with the Junkers Jumo 004B-1 turbojets like the Me-262, this would cause a shortage of engines for both aircraft, and this problem of supplying of the Junkers Jumo 004B-1 turbojets would not be solved until early 1945, by fitting the Ar-234 with four BMW 003A engines.
As 1943 came to a close, Germany was on the verge of introducing a very high performance fighter (Me-262), but with a large number of technical problems still existing, most of which were to do with the engines. This would not be an easy “birth” for the Me262, or even the Ar-234.
What would 1944 bring for the Me-262 and the Ar-234?
To be continued, if there is any interest in this TL?
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