Dornier Do. 335 Flight Test Footage

stona · May 17, 2017

The projected performance for the Do 335 A-0/A-1 was 608 kph/378 mph at sea level, 770kph/478 mph at 8,000m.The most Rechlin got out of any Do 335 actually flown was 730 kph/454 mph.
Goering was told (on 23rd May 1944) that the Zerstorer would make 745 kph and the bomber version 760 kph, but theoretical projections, particularly for service aircraft with all the added equipment that they invariably comprise is a very inexact science.

Whilst even the actual figures for the Do 335 show it to be considerably quicker than a Mosquito (we'll stay away from the fantasy figures some are keen on), I doubt it could out Mosquito the Mosquito. It would have made a good photo-reconnaissance aircraft, but the Germans already had a jet for that. It might have made a good night fighter, but by 1945 it wasn't the aircraft platform that was the issue, it was the lead established in the electronics field by the allies, particularly the British,that was blinding the nachtjagd. The Mosquito made a very good night fighter. It could have potentially matched the Mosquito in an anti shipping role, if the Germans developed the units, weapons and tactics to match Coastal Command's anti shipping wings, something that had taken the British several years. The Mosquito's contribution as a bomber, apart from a handful of special operations, was as an adjunct to the strategic bombing campaign, as an intruder, pathfinder and, very successfully, in the Light Night Striking Force, all of which was pretty irrelevant to Luftwaffe operations. There was no strategic campaign to join.

It is perhaps important that in the real world, according to the November 1944 production plans, the Germans planned to build most Do 335s as Zerstorer (2118) and Night Fighters (1881) by March 1946, along with a few trainers. They'd given up on the fast bomber at this time, a role initially favoured but one planned for the jets, to add to the fantasy the Ju 287 gets mentioned in this role (along with the Ju 388 and Ar 234).
They planned just 4,000 Do 335s to be produced roughly a year after the war was over! They planned fewer than 80 by the time the war actually ended. Both figures are pure fantasy.

I apologise for the over use of the word 'fantasy', but it is difficult to write about these late war German projects without repeating it

Cheers

Steve

Koopernic · May 17, 2017

stona said:
The projected performance for the Do 335 A-0/A-1 was 608 kph/378 mph at sea level, 770kph/478 mph at 8,000m.The most Rechlin got out of any Do 335 actually flown was 730 kph/454 mph.
Goering was told (on 23rd May 1944) that the Zerstorer would make 745 kph and the bomber version 760 kph, but theoretical projections, particularly for service aircraft with all the added equipment that they invariably comprise is a very inexact science.

Whilst even the actual figures for the Do 335 show it to be considerably quicker than a Mosquito (we'll stay away from the fantasy figures some are keen on), I doubt it could out Mosquito the Mosquito. It would have made a good photo-reconnaissance aircraft, but the Germans already had a jet for that. It might have made a good night fighter, but by 1945 it wasn't the aircraft platform that was the issue, it was the lead established in the electronics field by the allies, particularly the British,that was blinding the nachtjagd. The Mosquito made a very good night fighter. It could have potentially matched the Mosquito in an anti shipping role, if the Germans developed the units, weapons and tactics to match Coastal Command's anti shipping wings, something that had taken the British several years. The Mosquito's contribution as a bomber, apart from a handful of special operations, was as an adjunct to the strategic bombing campaign, as an intruder, pathfinder and, very successfully, in the Light Night Striking Force, all of which was pretty irrelevant to Luftwaffe operations. There was no strategic campaign to join.

It is perhaps important that in the real world, according to the November 1944 production plans, the Germans planned to build most Do 335s as Zerstorer (2118) and Night Fighters (1881) by March 1946, along with a few trainers. They'd given up on the fast bomber at this time, a role initially favoured but one planned for the jets, to add to the fantasy the Ju 287 gets mentioned in this role (along with the Ju 388 and Ar 234).
They planned just 4,000 Do 335s to be produced roughly a year after the war was over! They planned fewer than 80 by the time the war actually ended. Both figures are pure fantasy.

I apologise for the over use of the word 'fantasy', but it is difficult to write about these late war German projects without repeating it

Cheers

Steve

The curves state "Erflogne Werte" which translates as "Flown Values". The triangle on the curve says ▵ Erprobungs Komand of OKL which would be "Ober Kommando der Luftwaffe" i.e. Test Group of the High Command of the Luftwaffe" not e-stelle Rechlin.

The curves in my chart clearly show 745kmh which is 460mph more or less as you stated but this is with the DB603E Engine. Whomever told Goering that the aircraft could do 478mph may have been telling the truth if it had been intended to offer the Do 335 with The DB603EM Engine. The EM was designed for C3 fuel plus MW50 but was cancelled when C3 fuel shortages started to develop due to the allied oil bombing campaign. But for this the Ta 152C would have entered service before the Ta 152H. Because of the Ta 152C was delayed till the DB603LA became available as this could produce high levels of power on B4 fuel.

I'm inclined therefore to trust the 490mph top speed as The DB605LA equipped Do 335 had slightly more power at a much higher altitude and because proper aerodynamic data at 460mph was available from runs with the DB603E.

Engines designed for C3 had higher compression ratios.

Koopernic · May 17, 2017

Shortround6 said:
Sometimes otherwise informed, experienced men went too far down a certain path. There are a number of theoretical reasons behind the configuration the Do 335 used. Unfortunately to realize some of the benefits required a lot of development work and work on details that conventional aircraft didn't need. Much like the He 177 's coupled engines were supposed to offer 3% less drag than 4 separate engines, maybe they did, maybe they did even better, but was the 3-4% reduction in drag worth all the problems?

The DO 335 offered some advantages but then there were disadvantages to the layout too. Conventional twins, much more often than not, used the engine nacelles to house the main gear, leaving a good part of the wing free for fuel tanks near or on the center of gravity. If you want to house the landing gear in a smooth wing (no bulges/fairings) you are using up some of the fuel space which needs to go in the fuselage on or near the center of gravity. The DO 335 then stuck a weapons bay/bomb bay in the bottom of the fuselage on/near the center of gravity. Great for a long range/high speed bomber with a small payload but between the bomb bay and majority of fuel housed in the fuselage the Do 335 wound up with a rather large fuselage for single/two seat aircraft which negates some of the drag reduction of putting the engines inline.
I am not saying one way was better, they were different and most of these late war aircraft were exercises in packaging in a way that the late 30s aircraft were not. The late 30s aircraft didn't have enough power to cram the air frame full of "stuff".

One thing distinct about the Do 335 is the very dense concentration of equipment in the Dornier 335. Most twin aircraft were empty aft of the trailing edge. The Do 335 was packed as dense and had an engine in the tail.

An full utilization of internal valume means low surface or wetted area and low drag.

Shortround6 · May 17, 2017

Koopernic said:
An full utilization of internal valume means low surface or wetted area and low drag.

It also means harder assembly and more difficult maintenance but it was the way of the future and combat aircraft became more densely packed even in the late 40s and early 50s.

tomo pauk · May 17, 2017

Koopernic said:
...
I'm inclined therefore to trust the 490mph top speed as The DB605LA equipped Do 335 had slightly more power at a much higher altitude and because proper aerodynamic data at 460mph was available from runs with the DB603E.
...

At 10 km, the 603A was to produce just under 1000 PS, the 603E perhaps a 100 PS more, while the 605L (2-stage variant of the line, C3 fuel) was supposed to be good for 1500+ PS. Quite a difference.
The 605LA was with intercooler, was allowed for B4 fuel.

Koopernic said:
One thing distinct about the Do 335 is the very dense concentration of equipment in the Dornier 335. Most twin aircraft were empty aft of the trailing edge. The Do 335 was packed as dense and had an engine in the tail.
...

The rear engine was not in the tail, but just after the fuselage fuel tank. The extension shaft connected rear engine with prop, not unlike the P-39/P-63 engine installation looked front-to-back (the Bell fighters featuring reduction gear next to the prop, rather than as a part of engine itself).

stona · May 17, 2017

Koopernic said:
One thing distinct about the Do 335 is the very dense concentration of equipment in the Dornier 335. Most twin aircraft were empty aft of the trailing edge. The Do 335 was packed as dense and had an engine in the tail.

There's not much crammed in behind what is effectively a mid-engine driving the rear propeller via a shaft. There is still a largely empty fuselage boom (a very wide and deep one too) to which the tail is attached. The two engines in the inline configuration didn't make the Do 335 any longer than the more conventional Mosquito, so the Germans deserve some credit for that

What would you have done with the Do 335? I'd have scrapped it.

Cheers

Steve

tomo pauk · May 17, 2017

Doesn't a call for scrapping a ww2 aircraft invoke an immediate ban here?

KiwiBiggles said:
The waste of time and resources becomes even clearer when you compare the Do 335 to its conventionally-laid out contemporaries, the de Havilland Hornet and the Grumman F7F Tigercat. The unconventional design lead an aircraft with very much the same performance and warload characteristics (about 470 mph, 4 cannons, 2000 lb bombload), with a far worse cockpit view, cooling difficulties, and highly problematic emergency exit. Not to mention how the much greater polar moment must have lead to decreased manoueverability.

Germany would have been much better served investing the effort in a conventional design. Something like a Hornet was well within their capability.

The rear engine was not installed at the rear, but pretty close to the Cog, thus no great probelms with polar moment. On the other hand, not having two 1- to 1.5-ton powerplants away from centreline healps with rate of roll. Having the engines sticking out in the nacelles will block pilot's view.
It took time for the F7F to beat 430 mph mark, and when it did it was still as good as P-47 of 1943; F7F never arrived at 450 mph in service. Germans tried a classic twin with Me 410, it was handily out-performed by Do-335 even with same engines, and using same era airfoil, and a bit bigger wing area.
This is not to say they couldn't do a 'Hornet minus'.

stona · May 17, 2017

Koopernic said:
The curves state "Erflogne Werte" which translates as "Flown Values". The triangle on the curve says ▵ Erprobungs Komand of OKL which would be "Ober Kommando der Luftwaffe" i.e. Test Group of the High Command of the Luftwaffe" not e-stelle Rechlin.

The Do 335 was tested at Rechlin, various aircraft were assigned there at different times. Ekdo 335 was established at the Dornier plant at Mengen, and personnel were to move there in October 1944. There were also various Arbeitskommando at other Dornier facilities where future ground personnel would be trained. All of this came under Luftwaffe control, so it is hardly surprising to see a test report published under its test command.
Cheers
Steve

GregP · May 17, 2017

The Do. 335 is interesting but, with only 37 built, it is even less of a factor than the Ta-152, which wasn't a factor at all. Both remain impressive, at least to me, but did absolutely nothing to help Germany win the war. I think of them as examples of what might have been in the fray had the war in Europe been extended. I'm certainly glad it wasn't extended.

stona · May 17, 2017

I think it is telling that plans were made for nearly 2000 Do 335 night fighters at a time when the Luftwaffe was so utterly defeated that their potential targets, the bombers of the RAF, were able to operate by day as well as by night. Fantasy!
Cheers
Steve

Dornier Do. 335 Flight Test Footage

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