Why did WW2 Germany Start Welding Engines Together? DB 600 Double Motors

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In his autobiography 'He-1000' Ernst Heinkel described the disbelief that he and He-177 Chief Engineer Hertel felt when Generalluftzeugmeister Udet expected this 4 engine aircraft (already expected to meet stringent performance demands for a late 1930s heavy bomber) to be capable of dive bombing. This led to extra structural reinforcement which added weight and reduced payload and performance and left them scrambling for ways to make up for these losses. If I recall correctly, the idea of reducing drag with coupled engines cooled by surface evaporation (which was dropped early on) arose from attempts to claw back performance losses caused by the dive bombing requirement. This had worked well for the He-119, so it seemed like a good idea. Heinkel held Hertel responsible for the missing DB-606 firewall and later fired him for allowing it. Heinkel offered a new He-177 version with new wings supporting 4 discrete engines as you describe in the video, only (as he put it) to be declined by a piqued Goering, personally embarrassed before Hitler due to the ongoing failure of this aircraft who ordered Heinkel make the He-177 work with coupled engines. While attempting to do so, Heinkel built two of the the 4 discrete engine versions in secret out of the view of Goering in France (the Farman He-274) and in Vienna-Schwecat (the He-277B). Both were said to have shown really promising performance and the Farman was used by France after the war into the 1950s for launching high speed test aircraft. Thus Germany lost it's final chance (perhaps too late to be of much use) at a possibly first class heavy bomber. Goering was adept at deflecting personal blame. He told Heinkel that Udet had told him the He-177 was required to dive bomb, which he rightly considered to be madness. Sounds like he dismissed coupled engines after the fact the same way. Much of this grief might have been avoided had the Jumo-222 appeared on schedule, but it arrived late in the war and really wasn't ready for operations. Junkers just didn't have enough qualified engineers to oversee production plus intensively develop this 24 cylinder engine. Contrast this sorry tale with the Avro Manchester. This was a heavy bomber built around the Rolls Royce Vulture X shaped engine that turned out like the DB-606 to be unreliable in service. Rather than being forced to waste time and resources making the unworkable work, its designer Roy Chadwick was allowed by the British Air Ministry to redesign the wings to carry 4 Rolls Royce Merlins, resulting in the hugely successful Lancaster. So much of the engine technical problems the Luftwaffe suffered was due to remarkably poor technical oversight from the RLM. In another video you mentioned the German lack of equivalent to the British use of RTOs to report what was happening in the engine development and production which held the British engine manufacturers to account. Had Germany somehow been able to find back-channel sources of strategic minerals like tungsten, chromium, tin and manganese specifically for engines, backed up decent official technical oversight, one can only imagine the engines they might have made. Given all of that, what they achieved - especially in gas turbines - was pretty extraordinary IMHO. Heinkel made a point during in his book that the imposition of The Treaty of Versailles sought to destroy Germany's ability to produce viable military aircraft. In his view the interwar years showed it had failed to significantly affect German air-frame design but that it had seriously impacted reciprocating engine design and development. He had considered moving into building such engines himself, but he considered Jumo, BMW, Bramo and DB had too big a lead for that. Besides Heinkel was aware of transonic propeller tip speeds limiting the ultimate performance of propellers. So he chose a different direction and pioneered jet aircraft - for which once again his efforts appear to have been slapped down by the RLM. Great video! Totally enjoyed it.

This double engine was also used in the Messerschmitt Me 261, where it worked well. But in the Me 261 the double engine was installed in wide nacelles that cantilevered in front of the wing. While in the He 177 the double engine was buried in a narrow, cramped compartment that blended with the wing. This made it very difficult to service and very prone to fires.

Love this. I've always been obsessed with the DB series of engines. Thank you for the time and effort you have put into making these videos.

The Napier Sabre 24 cyl engine in the Typhoon also had two crankshafts although this was how it was designed - not done as an after thought. It had its fair share of teething problems (which included catching fire) but really came into its own once these were ironed out. It had sleeve valves and was really compact making it also tricky to work on and a lot of special tools were required.

I'm reminded of later work with coupled engines. Specifically the F-84 Thunderscreech with the supersonic propller and coupled turboshaft engines, and the A2D Skyknight with a similar layout. Ed Heinamann likened the gearbox trouble to a chronic toothache, and walked away in disgust. A rare thing for the man. The Thunderscreech was deemed a death trap early on. It does puzzle me from this distance why Dornier's 335 wasn't gaining more attention. Seems safer at every stage.

Great video. DB606 was also licensed by the Japanese Navy and imported in 1941. This was used as a reference when making the inverted-W24 for the Navy's prototype 'Keiun'. By uprating Atsuta (DB601) from 1,200->1,700 horsepower and coupling, Keiun was inevitably only an "expensive toy", but it's still interesting engineering. 3,400 takeoff horsepower!

The tree DB 600 engines series shared similar issues with all double engines that was tried to be produced like the Vulture all sharing similar unreliability due to the excessive heat generated by inner exhaust system possibly because of badly cooling system. The other issue was that the DB engines was built too near the main spar with no firewall despite the criticism of the engineers. The real failure of the DB 600 engine series was the enormous waste of resources and time when it could be easily built like the Lancaster but unfortunately it was built with a moderately dive requirement requiring strengthening of the wings and of course weight. Really a good job, looking forward to see your next video 👍👍👍

I think at first they tried surface cooling, by sending the coolant in tubes below the wings plates, and it gave the bomber a speed well past the contemporary fighters! But at high altitude and low temperatures it made the plates crumple, so they had to add ordinary coolers, giving more drag, and needing defensive armament, and more weight and drag.

the sideways superchargers of the benz motors are pure art

The photograph of the HE-119 at 1:22 is interesting as it includes what appears to be members of a Japanese delegation. The 7th and 8th prototypes of the HE-119 were sold to Japan and insights gained were used to design the Yokosuka R2Y which also used coupled engines driving a single propeller.

Excellent overview. Super well done! I'm a big fan of your channel.

The machetti aircraft that still holds the float plane speed record was powered by 2 fiat engines one behind the other with shared induction systems I think...I suppose that's a success story? It killed its first three test pilots. I'm in awe of the man who went fourth....that's courage in my opinion.

The Fairey Prince and Monarch engines were also double engines (V within V), which flew in Fairey Battle, but were not proceeded with. A Monarch engine supposedly still exists at FAA Museum, Yeovilton, UK.

I love how you also discuss the logistics surrounding the engine!

Absolutely fantastic! I love the history of aircraft in vivid details

Excellent series. Don't forget to include the Soviet engines.

The Napier Sabre H-24 sleeve valve engine also flew and reached 3,500HP. And flew in Hawker Tempest and Typhoon.

Great video I really enjoy this detailed stuff As a note I am a blind subscriber and your audio was so good I didn’t miss the video Cheers

I appreciate the accuracy of your research. 👍