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Just think you've got 2 inverted V-12s side by side, the center 6 exhaust manifolds of each engine are either shared or very close together, in the bottom of the engine nacelle .
No engine is perfect. Some of them have tiny leaks, any leaked oil or any oil residue left from hurried routine maintenance, is going to end up at the bottom of the engine nacelle, which happens to be where the hottest area is.
If you look at a cutaway of the He177, see if you can see a firewall between the engine and the main spar of the wing. If there is no firewall, a engine fire won't take long to cause main spar failure. Also the engine oil tank is right behind that main spar, but they usually are close to the engine.
I'd say poor design decisions on both engine builder and airframe builder part.
Impolite to answer a question with a question but where could it have been successful?
During interrogation of Dr. Ernst Heinkel at the end of WWII, I suggested to him that his organisation seemed to enjoy more success with smaller aeroplanes than with large ones. His face displayed some annoyance when he replied that I must be referring to 'that accursed 177'. He associated Ernst Udet, the former Generalluftzeugmeister, in his mind with the whole disastrous story, and in particular the demand for a 60-degree diving attack capability which he blamed on Udet's influence.
Heinkel himself had not been very closely involved with the original design of the He 177. Dipl-Ing Heinrich Hertel had been Heinkel's Technical Director and Chief of Development during the initial development of the bomber but had left the Heinkel organisation in March 1939, and his departure at this juncture had not augured well for the future of the aircraft. In fact, in 1942, Hertel had returned to Heinkel as Reichsluftfahrtministerium Deputy with full powers to reorganise the development of the He 177. But it proved to be a case of closing the stable door after the horse had bolted, and Ernst Heinkel summed up his feelings when he said to me: 'I even look more kindly on the He 111Z than that 177!'
So what would it take to make it successful (the engine in the airframe and the aircraft itself)?
I think, as Heinkel said, the basic design was cursed and a return to the drawing board would be needed.
Methinks that choice of powerplant was the main problem. The dive bombing request and its implementation was not easing the situation either.
The dive bombing requirement forced Heinkel to strengthen the airframe to withstand the stress of dive bombing. This caused extra weight and required the use of two engines as the wing was not able to cope with stress caused by an outer wing engine in a 4-engine setup. Due to insufficient power from a single engine they used the coupled engines. The coupled engine was tightly integrated into the wing and that is one major cause of the issue with engine fires (too tight, improperly shielded), I can only assume this was initially made to reduce/limit CoG shifts (which would have forced even more weight in the rear to counter this).
The DB 605 as base engine of the later DB 610 couple added its own share of problems but those should have been solved/reduced by late 1943.
The aerodynamically good/clean design (also caused by twin engine setup) had positive aspects - the aircraft had rather high speeds which could be improved by using a shallow glide approach to target and away from it. During operations over England in 43/44 the He 177 had the lowest loss rate of the involved bombers, most likely due to their speed advantage.
If you are going to use push-pull you better decide at the start. Shifting a pair of engines from the front of the wing to the back plays havoc with the CG.
It also pretty much dictates tricycle landing gear as a tail dragger with props on the back of the wing either needs stilts for landing gear or very small props.
Wouldn't a lot of those problems have been avoided if upright V orientation had been adopted rather than the inverted V?Just think you've got 2 inverted V-12s side by side, the center 6 exhaust manifolds of each engine are either shared or very close together, in the bottom of the engine nacelle .
No engine is perfect. Some of them have tiny leaks, any leaked oil or any oil residue left from hurried routine maintenance, is going to end up at the bottom of the engine nacelle, which happens to be where the hottest area is.
If you look at a cutaway of the He177, see if you can see a firewall between the engine and the main spar of the wing. If there is no firewall, a engine fire won't take long to cause main spar failure. Also the engine oil tank is right behind that main spar, but they usually are close to the engine.
Well obviously the wings will need some redesign like the He 177B, but it shouldn't be too much of an issue, right?
Quite a few successful Dornier sea planes flew with the push-pull arrangement. One of them the Do 26 was one of the longest ranged aircraft ever built.
During operations over England in 43/44 the He 177 had the lowest loss rate of the involved bombers, most likely due to their speed advantage.
Were there any German pilots that spoke of it in a positive light? The only real commentary I have read is from Eric Brown - and he was not fond of it ... to put it mildly.