S/E lightweight Pusher Do 335.

[wuzak]

Could a lightened single engined version of the Dornier Do 335 have been useful for the Luftwaffe in the latter stages of ww2?

Removing the forward engine would save at least 1000kg (2205lb) of the weight, while allowing nose armament and/or nose mounted radar systems.

It wasn't ever going to be as fast as the Do 335 with 2 engines, but it should have been a 400mph+ fighter.

 

[Aozora]

I doubt very much whether a single-engine Do 335 would have been able to achieve 400+ mph - even without the front engine it would still have been a large, hefty aircraft for the power. However, Dornier had all sorts of concepts for improved Do 335s, or for aircraft following a similar design philosophy, including the Do P247/6-01 which was a single seat, single engine fighter driven by a pusher Junkers Jumo 213 J. The 213 J was a projected variant of the 213 A using four valves per cylinder rather than three, with a single-stage, three-speed supercharger, and able to produce 2,600 hp. It was smaller (12.5 m [41 ft] wingspan, 12.0 m [39.5 ft] long) with a cut down rear fuselage and three piece bubble canopy similar to the Me 262. Unfortunately there are no projected performance figures. (J Richard Smith, Eddie J Creek: Dornier Do 335 Arrow, page 149)

http://www.luft46.com/rmart/rm247.jpg

 

[GregP]

Perhaps not a single engine version of the Dp 335, but a smaller similar design with the rear engine layout might have been interesting ... but it would still have the same weaknesses, only worse. The rear engine would have been vulnerable to any rear attack. The fin would have also been a blow-away unit, as would the prop.

So, what would it buy you that outweighs the disadvantages?

 

[pattern14]

There were swept wing projected models, but like all that luft 46 stuff, amounted to nothing that would have really helped the situation. Post war, the Do 335 was a curiosity, and has often been cited as one of the fastest piston engined planes of WW2, but ultimately ended up being a has- been that never was. Still, an intriguing concept, and another engineering feat of the Luftwaffe.

 

[wuzak]

but it would still have the same weaknesses, only worse. The rear engine would have been vulnerable to any rear attack.

Any more than a P-39/P-63?

So, what would it buy you that outweighs the disadvantages?

Unobstructed centreline forward firing armament.

 

[wuzak]

I doubt very much whether a single-engine Do 335 would have been able to achieve 400+ mph - even without the front engine it would still have been a large, hefty aircraft for the power. However, Dornier had all sorts of concepts for improved Do 335s, or for aircraft following a similar design philosophy, including the Do P247/6-01 which was a single seat, single engine fighter driven by a pusher Junkers Jumo 213 J. The 213 J was a projected variant of the 213 A using four valves per cylinder rather than three, with a single-stage, three-speed supercharger, and able to produce 2,600 hp. It was smaller (12.5 m [41 ft] wingspan, 12.0 m [39.5 ft] long) with a cut down rear fuselage and three piece bubble canopy similar to the Me 262. Unfortunately there are no projected performance figures. (J Richard Smith, Eddie J Creek: Dornier Do 335 Arrow, page 149)

http://www.luft46.com/rmart/rm247.jpg

http://www.luft46.com/dornier/dop247.html

That says projected 519mph.

So, you think it would need a more powerful engine than the DB603 to achieve decent performance?

 

[wuzak]

Ok, what if the Do 335 was developed from the start as a light s/e pusher type fighter (rather than a bit of everything)?

 

[Capt. Vick]

I don't think it would be worth while. The US experimented with this with a line of pusher fighters: XP-54, XP-55 and XP-56 and none of them where awarded a production contract, being no better than fighters already in production.

 

[wuzak]

Well, let's look at those.

The XP-54 chose an engine that was cancelled, so chose an engine which was under development but would not go into production. It was as big as a P-38 and had odd tech choices foisted upon it - such as the moveable 37mm cannon mount. First flew in January 1943.

The XP-55 was unstable. Except when inverted with no forward speed. Wiki's specs show a 390mph top speed - will have to check that later. But that would be faster than a similarly powered P-40. First flew mid 1943.

The XP-56 was re-engined with the R-2800. Which made it fat. Which caused poor performance. The XP-56 was also unstable, and had modifications aimed at rectifying this. It also required a special reduction gearbox for contra-rotating props, which took time and delayed it flying (second half 1943). The XP-56 also used a new construction technique and new materials - ie magnesium - for the airframe. Northrop had to invent new welding techniques as well as plane the sheet magnesium, because it wasn't sufficiently consistent in thickness from the supplier. As far as I can tell, the XP-56 was not able to actually do more than ~320mph in flight, and had a projected speed of ~350mph (by NACA).

So, no those weren't in any danger of being put into production.

 

[Capt. Vick]

So... You're agreeing with me right?

 

[wuzak]

Those particular aircraft were not very good candidates for production.

The XP-55 and XP-56 also had more radical and untested layouts - a canard and a flying wing. The XP-54 was less radical, but with booms and a pusher prop it wasn't exactly conventional.

The Do 335 was much more conventional, aside from the pusher prop.

 

[l'Omnivore Sobriquet]

It is not the rear engined that should be removed.

I think of a crude 'field' armoured ground attack and tank buster version. Keeping the rear pusher, changing wing and everything in front.

From the Do-335 you would save the entire rear section (hopefully with some extra armour, discarding any altitude gear), and allowing for any kind of V-12 then in production. Keep the undercarriage also, quite oversized so very good for rought field employ (or set a double Fw-190 wheels for each leg.)
For the wing, get some wide straight design optimized for lift, maneuvrability and low speed safety plus multiple underwing ordnance pylons. Much à la A-10 or Skyraider.
In front, a very small very armoured cockipt with minimal rearward view, und under it a 'big gun' of your choice.
Have a pair of mg-151 at wing roots as standard. Don't let expelled cartriges mess with the propeller. Eventually, further along the wing either some lower caliber 'sprayers', or a mk-108. Flaps and all control surfaces should be oversized and redundant* (so possibly have an increase in size of the upper fin, not too difficult to produce and making both fins redundant, just what you want.)

I think we're having a very good 1945 successor to the Henschel 129, bettering the Sturmovick as long as rearward gunner doesn't prove necessary. It shouldn't, keeping the thing clean and 'light'. Doesn't evade comtemporay ennemy fighters though, but fast nonetheless, very manoeuvrable, amazingly solid and most resistant to gunnery up to 20mm (up to a certain amount that is...), and most dangerous even for fighters. Very easy field maintenance etc.
Non ?

Can even think of a bomber-buster variant, this time with a different wing for speed at atlitude, lighter armour of course, and lighter main gun, but retaining the idea of a small sized armoured 'front office' with one big gun. Make sure, this time, that you have the proper engine for the demanding task, has to be speedy at altitude or else it will Mustang meat... yet with bones. Could be interesting in case the Ta-152 shows insufficiant, Do-335 too expensive and jets too scarce. The idea being a reborn of the 'long gun, out of defensive range shooting', that got swept away by the first Mustang waves of 1944, mixed with the optionnal 'company front assault' of later fame... Keeping some reasonnable armour is a must ; I think the thing would have to be excorted by some late-mark lighties, who could be able in turn to start cutting slices to the fighter escorts in dedicated engagement at last, which should be interesting in this 'what if', continued battle.

* Redundant : sufficently numerous so that the loss of one doesn't impair the function, carried on by the remaining one(s). I think the word is correct in English...

 

[OldSkeptic]

Why a pusher? Just makes for terrible engineering problems to overcome, CoG for one thing, cooling, et al.
You lose lift at takeoff and low speed.

Frankly I am at a loss to work out any advantages of the idea.

 

[l'Omnivore Sobriquet]

Well, standard jets are pushers. Most of the engereering would be done already, the idea is to take the rear fuselage of the 335 almost unchanged. CoG balanced by the armour in front + gunnery, and hopefully an easy re-positionning of the wing itself.
As for 'loosing' lift at take off and low speed, perhaps but the A-10 still is a pusher, and I don't think a propeller at the rear of a fuselage would get much trouble from disturbed air from the wings. Besides you get a clean air upon the wings, if not 'blown'.
As for advantage for the formula, there is simply no other way round, if you want to put a big gun in a single engined aircraft. Plus the front view for the pilot even in a small armoured 'helm'.

 

[wuzak]

Why a pusher? Just makes for terrible engineering problems to overcome, CoG for one thing, cooling, et al.
You lose lift at takeoff and low speed.

Frankly I am at a loss to work out any advantages of the idea.

Why is the rear mounted (liquid-cooled) engine any more of a challenge to cool than a front mounted engine?

 

[GregP]

The empty weight of the Do 335 was over 11,000 pounds witha gross weight of more than 19,000 pounds. You can't take that airframe, remove an engine, stuff in armament and still expect to have decent performance.

In combat, the P-39 didn't suffer from any extraordinary vulnerability from the rear. It also didn't carry explosive charges to blow away the fin and rear propeller. The Do 335 did have those features. And from the few WWII newsreel films I have seen of it, wasn't well suited to rough field operation.

I don't see any partitularly good use for the configuration in the WWII timeframe. Maybe the proposed unit with a DB 603A in front and a jet in the rear, IF the jet made it faster ... but it was never built. There never HAS been a successful warplane with two pistons engines in centerline configuration that made it into production in quantity or did anything in a war to my knowledge.

They made two Ambrosini SS.4 that didn't succeed, but it was only single engine like the proposed single engine variant of the Dornier in this thread. We made the Douglas XB-42 but it has twin rear contra-props and was abandoned after being converted into a pure jet. They DID build the Fokker D.XXIII, but only one. They only built two Heston A.2/45's, but it wasn't a fighter. The Miles M.35 was only built as an aerodynamic proof of concept, was never built as a fighter, and was a single gnine aircraft. They only built one Moskalev SAM-13. Our own three rear engine fighters prototypes were all not selected for production, as stated above. They made 198 SAAB J-21's, but they were single engine, not centerline twins, and didn;t exactly set the world on fire.

So the layout has never been proven to be useful despite any and all attempts to date.

 

[wuzak]

The empty weight of the Do 335 was over 11,000 pounds witha gross weight of more than 19,000 pounds. You can't take that airframe, remove an engine, stuff in armament and still expect to have decent performance.

Take out the front engine and you are going to save at least 2,500lbs. So empty weight comes down to 8,500lb at most.

FWIW P-47 empty weight was ~10,000lb.

 

[wuzak]

The second XP-55 prototype was measured at 377.5mph @ 16,000ft on Military Power (from Balzer, American Secret Pusher Fighters of WW II).

Not as fast as a P-51A, but as fast or faster than a P-40 with similar engine.

 

[GregP]

Take out the front engine and the nose will rise up and the tail will sit on the ground. Add armament to balance it out and you have half the power it had when it went fast and you're back to the same empty weight if the CG is in the same place. Say it went 474 mph with two 1750 HP engines (I know they were 1726 HP without MW 50 or GM-1). The same plane, if it was counterbalanced with armament should go 359 mph at the same altitude and have an anemic climb rate. That assume it could GET to the same altitude. Down low it would likely be the slowest thing around.

The XP-55 was proven to be a failure so its speed, while a modest improvement over the P-40, is of little real world value. The conventionally configured XP-47J went over 500 mph. The conventionally-configured P-47N and Ta-152 were both quite fast, too. The lightweight XP-51's, like the J model, were also quite fast.

In fact, the only fast piston twin of centerline thrust configuration was the Do 335, which never made it into combat as far as I know, exccept maybe to get chased once on a test flight. The total build for the Do 335 was something like 37, none of which ever did anything except conduct some fast test flights.

Hardly a record to inspire immitation as a possible combat plane I would think. Unless yoiu also fitted it with an ejection seat, I'm not sure you'd find any volunteers to try to bail out of it either.

 

[wuzak]

Unless yoiu also fitted it with an ejection seat, I'm not sure you'd find any volunteers to try to bail out of it either.

The Do 335 did have an ejection seat.