A better thought-out '2nd gen' of German 2-engined A/C?

[wuzak]

So we are designing a '2nd gen' if German 2 engined aircraft but question is for what missions ?

Exactly.

Are we planning to replace specific types in specific roles?

How many types do we need? Do we want a single aircraft to do all the specified roles, or two or three specialised types.

For example Me 210: if it was good from start ( like Me 210ca ie Db 605 powered Hungarian version ) it would be good light bomber even with original DB601. As for zerstörer or night fighter not so much.
It fit in category but it was to late, first flight September 1939 frontline units April 1942.

IIRC, 1942 was the target date of the OP. Or maybe 1941?

In any case, if the Me 210 wasn't messed up in the first place it may have been available earlier.

Personally, I would make the Me 210 the long range fighter, a replacement for the Me 110.

I would lose the internal bomb bay and the remote defensive guns.

As a night fighter, it should be suitable to use the radar aerials that were used by Germany for most of the war.


For a bomber you'd probably be looking at a Ju 288, or maybe a smaller version of it.

 

[tomo pauk]

So we are designing a '2nd gen' if German 2 engined aircraft but question is for what missions ? To be counterpart (to performances and/or missions ) of Mosquito or A-26 or Wellington or ...also when is important question.

'When' question is adressed in the OP - service use by some time of 1942, at least.
Missions - heavy fighter LR fighter, LR recon, fighter bomber, 'normal' bomber, night fighter. One airframe might be over-taxed to do it all well, so more prudent approach could be to divide these missions to two designs.

Well if we change timeline .... then we may get la raison d'être. A then we can, with pleasure , design appropriate airplane.

I don't want to be rude or offensive and I like to read wiff and learn about projects and different people's ideas but I like to put them their corresponding framework.

And my apologies to native English speakers for my lack of knowledge of the language.

No worries, mate

greetings from Adriatic

Where from, exactly?

 

[Zmauky]

Where from, exactly?

Well, currently in Zagreb with a tendency towards Cres

 

[tomo pauk]

Greetings from Kaštela

 

[Zmauky]

Greetings from Kaštela

We'll I somehow suspected from the picture .

But let's continue with thread...
2nd gen airplanes depends on 2nd gen engines. DB 605 / Jumo 211F/J - they can only be an upgrade to the first generation (Me 109 / He 111 ect)
So let's assume that the development of Jumo 213 and Jumo 222 went smoothly and that we have production during late 1941/ early 1942 then we can have:

- heavy LR fighter / night fighter
Ju 88G with Jumo 213 (big enough for all night gear or enough fuel for the Bay of Biscay, for example )

- medium bomber
Ju 288 with Jumo 222 (first iteration with small wings, 3 crew and Jumo 222a/b)
Do 217 with Jumo 222 ( why not, production is there and with Jumo 222 it won't be underpowered)

light bomber - if it is needed at all then metal Ta 211 (or Me 210/410)

recon - I always liked the idea of using the He 100, with steam cooling, but also with cameras in the fuselage behind the cabin, although it is not a twin-engine plane .

So we are discontinuing the production of Ju 88/188 Bomber variants (or small production for dive bombing) for more fighters, and also all BMW 801/ DB 603 from Junkes and Dorniers can go to Fw 190C and Fw 190F/G.

He 111 is by then replaced by He 177 ( when there had to be 1 propeller, why didn't they put the motors one behind the other ? ) so maybe we also need DB 605 engined Fw 187.

In fact, when I read this written above, we return to the well-known fact that the Luftwaffe lost the technological battle - because it stayed with the first generation of aircraft because there were not enough strong engines for the second generation.

 

[don4331]

My take on solution:

1st generation:
1934: Bf.109 as SR fighter.
1935: Instead of Bf.110, Bf.109Z (Twin Ju.210, 8 - MG17s <2 in wing outer panels, 2 in each cowl, one in center wing and one rear>. Proof of concept using 4 x Bf.109B main landing gear; production will move to just 2 main gear. As the outer wings no longer house landing gear, use the space for fuel. The "B team" cuts their teeth on this design.
"A Team" focuses on Bf.162 (think Me.210 but with original twin tail/without remote control rear armament). As this is pre-war, there is time for testing and correcting fuselage length if they get it wrong.
Between Zwilling and Bf. 162, you have heavy fighter LR fighter, LR recon, fighter bomber, 'normal' bomber.
Fw.187 never happens because there is nothing it can do that Bf.109Z can't.

2nd generation:
1942: SR fighter is turned over to Fw.190
Bf.109Z is aerodynamically cleaned up (think Bf.109F) Power plant to 601F, then 605. Armament moves to 5-MG17s/3- MGFF then to 5 - MG151/20, 4 - MG 131 and MG81.

3rd generation:
Me.262
Ar.234

I'm still working on the bombers; really need an 18 cylinder radial...

 

[don4331]

He 111 is by then replaced by He 177 ( when there had to be 1 propeller, why didn't they put the motors one behind the other ? ) so maybe we also need DB 605 engined Fw 187.

How separated are you making the 2 motors?

Common ala Fiat AS.6 from Macchi M.C.72 with engines back to back. If so, how are you driving the supercharger(s)

View: https://www.youtube.com/watch?v=yJB-iCtt9zw The back fire through the carb (both the initial and at the ceremony) when starting the 1st engine is impressive...

or some distance apart at Kawasaki Ha.201 from Ki-64?
Note: The twin Klimov M-103 in the Bolkhovitinov S-2 didn't make expected power/tended to break the rear propeller shaft (I suspect because the torque twisted things out of alignment - hard to make things light enough for an airplane, yet strong enough.)

 

[Zmauky]

How separated are you making the 2 motors?
Well using the KISS principle - the point is that we are looking for a way to drive 1 propeller (and avoid all the problems of the DB 606 series). We don't even have to physically connect them, speaking from memory the DB 60x has 70mm room for a shaft instead of a cannon, just put a common transmission in front of the first one . Admittedly, we got a long engine nacelle, but fortunately the landing gear legs of the He 177 are double anyway.
In fact, even a two engines side-by-side and a completely separate transmission would probably be a better and simpler and faster (with slightly more occupied space and slightly heavier) solution. And rather simplified maintenance.

 

[tomo pauk]

I'm still working on the bombers; really need an 18 cylinder radial...

See here ...

 

[tomo pauk]

For the tandem configuration, a look on the Japanese Ki 64 might be interesting. Proportions of the P-47 (but with a more slender fuselage) or of the Tempest, a fighter like that in German service will be getting rid of the surface cooling by this time (early 1940s). Power vs. drag in 1942, we look at sorta Tempest with the post-war Sabre VIII, or 30-50% more power, depending on altitude. Even hanging the two MK 103's under the wing is worth it. For the long range work, keep the armament at 4 20mm cannons, attach a 900L tank under fuselage. It should work as a fast bomber too (but not too rangy).

 

[wuzak]

In fact, even a two engines side-by-side and a completely separate transmission would probably be a better and simpler and faster (with slightly more occupied space and slightly heavier) solution. And rather simplified maintenance.

You mean like a DB 606 or 610?

 

[Zmauky]

You mean like a DB 606 or 610?

Yes, but not connected in one unit (like DB 606 or Allison V-3420), more like in Bugatti 100 racer.
I think it's always faster and simpler to assemble parts off the shelf that work than to design from scratch ( and encounter unexpected problems and make mistakes and...). With the DB 606, they first tilted the engine axles and then rammed the exhaust on the exhaust - hmmm sounds like a possible problem . It ( two separate engines ) may not be the most ideal (easiest / smallest, etc.) solution, but it is certainly the fastest and simplest (if one wants one propeler). And in this case it greatly simplifies logistics and maintenance (let's say you can change only the engine that has been more worn or damaged). Is it worth more than 4 separated engines ? Well unfortunately, the correct answer requires a little more calculation from aerodynamics to the length of the supply lines. But anyway He 177 had only to propellers for different reason. Actually, I only mentioned it to explain the discontinuation of He 111 production.

 

[wuzak]

The DB 606 was two separate DB 601s, joined only at the gearbox (which was mounted to the fronts of the engines).

One had to have its accessory drive and supercharge mirrored, but was otherwise a standard DB 601.

Either engine could be isolated from the propeller drive by disengaging the drive to the gearbox.

The DB 610 was the same, just based on the DB 605.

One of the issues with the DB 606 was that by angling the engines to get them closer together the inner banks were nearly vertical, and oil could leak on to the exhausts and cause a fire.

In the He 177 there wasn't a firewall behind the engine.

 

[Zmauky]

We are getting out of scope of thread but,
I agree that the DB 606 did not share accessory drive and supercharges (like the fiat AS6). I also agree with you that db 606 is more or less 2x db 601 and a common gearbox, but still not quite.
We cannot take, for example, only the left (or rear) engine (of the two) and replace it. In addition, any engine aero or not (especially an inverted V) is not very happy with constant axis tilt. And how much distance is there between the exhaust and how much room is there for extra heating ( or oil drips) between the two inner blocks. Give them little bit off space. I think that all the advantages of the DB 606 (compact size, smaller transmission / shorter axles / simpler airframe attachment / lower total weight) are lost to the variant with two identical separate engines with common transmission (easier production, maintenance and logistics - identical engines, no special parts / production / design / testing/ - not to mention in a much shorter time to production).
I also agree that the nacelle design of the He 177 was problematic, but how much earlier and with fewer problems would it have been without the extra design time and all the initial problems with the DB 606 installation in relation to two separate engines and a common transmission on one propeller in a design like Ki-64 or Bugatti ?
And if the combination of DB 606 and He 177 was good, we would not be discussing it now .

 

[don4331]

How separated are you making the 2 motors?
Well using the KISS principle - the point is that we are looking for a way to drive 1 propeller (and avoid all the problems of the DB 606 series). We don't even have to physically connect them, speaking from memory the DB 60x has 70mm room for a shaft instead of a cannon, just put a common transmission in front of the first one . Admittedly, we got a long engine nacelle, but fortunately the landing gear legs of the He 177 are double anyway.
In fact, even a two engines side-by-side and a completely separate transmission would probably be a better and simpler and faster (with slightly more occupied space and slightly heavier) solution. And rather simplified maintenance.

That seductive mistress - the doubled engine - promising double the power for little effort (time/cost). Fiat, Daimler Benz, Rolls-Royce & Allison all courted her. Only to find out she was as expensive as a larger engine - issues with combining gear, superchargers, connecting rods, etc., etc.

70mm of room isn't that much. The shafts between engine and gearbox for the P-39 are 2-5/8" (~67mm) and 0.2" (5mm) wall thickness. For the Ki-64, as the DB engine is an inverted V, if you want shaft to run through the hole for the cannon (and keep pilot relatively low, you are running the shaft after reduction. So, you need a shaft 1.55 stronger... P-39 'twisted' its airframe over 90mm between static and full power that's with early Allison's (and shaft have 5-3/4* twist). The shafts in the P-39 also needed to accommodate the difference between landing with empty magazine (nose drooping as supported by wing) vs supported by nose wheel.

As I noted with the Klimov tandem engine, the combination didn't make expected power (and tended to break the shaft between rear engine and front propeller).

For the fore/aft engine combo - you can only bury engine so far into the wing before spars get in way. And all that weight at distance really twists the wing.

I will note that the Fiat, the Klimov and the Kawasaki are all powering 2 propellers. Minorly easier as front prop is identical to what would be on single engine; Majorly more difficult as the rear need both a larger interface (the front prop shaft needs to fit inside) and you need to fit the constant speed mechanism in (although that's probably not a lot different from a cannon through propeller).

If only that mistress lived up to the hype.

 

[wuzak]

That seductive mistress - the doubled engine - promising double the power for little effort (time/cost). Fiat, Daimler Benz, Rolls-Royce & Allison all courted her. Only to find out she was as expensive as a larger engine - issues with combining gear, superchargers, connecting rods, etc., etc.

Rolls-Royce didn't make a "doubled engine".

Zmauky is describing two separate engines coupled only in the sense that they drive the same propeller.

Like the twin Centaurus engine arrangement used to drive each propeller assembly in the Bristol Brabazon.

The DB 606 and DB 610 were close to that description. The main difference being that they had mirrored accessories and the change in orientation (to allow them to be closer).

 

[wuzak]

I also agree that the nacelle design of the He 177 was problematic, but how much earlier and with fewer problems would it have been without the extra design time and all the initial problems with the DB 606 installation in relation to two separate engines and a common transmission on one propeller in a design like Ki-64 or Bugatti ?

Tandem DB 601s could work in a He 177 style aircraft, provided that there is still space for the main landing gear.

 

[Shortround6]

'When' question is adressed in the OP - service use by some time of 1942, at least.
Missions - heavy fighter LR fighter, LR recon, fighter bomber, 'normal' bomber, night fighter. One airframe might be over-taxed to do it all well, so more prudent approach could be to divide these missions to two designs.

Part of the mission/s are range/endurance. What worked over England (barely) didn't work over Biscay, much of the Med, anything more than short penetrations of Russia and short endurance Night fighters were a problem.

So let's assume that the development of Jumo 213 and Jumo 222 went smoothly and that we have production during late 1941/ early 1942 then we can have:

In fact, when I read this written above, we return to the well-known fact that the Luftwaffe lost the technological battle - because it stayed with the first generation of aircraft because there were not enough strong engines for the second generation.

Yes, getting better engines would solve a lot of German problems
British would have loved less problems with the Hercules, Sabre and Vulture also.
Wright R-2160 actually worked

Between Zwilling and Bf. 162, you have heavy fighter LR fighter, LR recon, fighter bomber, 'normal' bomber.
Fw.187 never happens because there is nothing it can do that Bf.109Z can't.

Bf 109Z was pipe dream.
It was fast and............................it was fast and............................it was fast...................and.........................
There is only so much you can do with 12-13,000lb plane with 250 sq ft wing
Any comparisons with the F-82 will be filled in the circular bin upon arrival, The F-82 wing was 89% the size of a Tigercat and they had almost the same max take off weight.
Specs for the 109Z are rather ethereal. Prototype was a pair of 109Fs that never flew. Estimate performance is sometimes for a version with Jumo 213E engines.
Think Westland Whirlwind with Merlin 72 engines..............and anti-gravity paint.

The Bf 162 was another squib load. A range of under 500 miles with ten 110lbs inside? At least you can stuff 28 of the same bombs into a Ju 88A-1 and carry them about 25% further.
Yes the Ju-88 was slower. But needing 2 or 3 Bf 162s to carry the same bomb load is not what the Luftwaffe needed.

 

[tomo pauk]

Part of the mission/s are range/endurance. What worked over England (barely) didn't work over Biscay, much of the Med, anything more than short penetrations of Russia and short endurance Night fighters were a problem.

Range/endurance problem requires carrying a lot of fuel per HP installed, while not going with a too draggy and/or too heavy aircraft. Fw 187 ticks all the boxes.

Bf 109Z was pipe dream.
It was fast and............................it was fast and............................it was fast...................and.........................
There is only so much you can do with 12-13,000lb plane with 250 sq ft wing
Any comparisons with the F-82 will be filled in the circular bin upon arrival, The F-82 wing was 89% the size of a Tigercat and they had almost the same max take off weight.

Think Westland Whirlwind with Merlin 72 engines..............and anti-gravity paint.

We can compare the 109Z with P-47 with max internal fuel but 'clean', 300 sq ft wing. P-47C was at ~12600 lbs, early P-47D at 13200 lbs, bubbletop P-47s at 14500 lbs, P-47N (wing of 320 sq ft?) at 16400 lbs clean.
With external tanks, weight went to 17-17.5 K lb for the bubbletop P-47Ds, and just shy of 19900 lbs for the -N.
tl;dr - Wing loading will be high, but it will be manageable.

Speed was of essence back in ww2. The 109Z, compared with normal 109s, shaves a good deal of wing- and tail-related drag that each engine must propel through the air. It is certainly less draggy than the P-38, while having comparable thrust.

Specs for the 109Z are rather ethereal. Prototype was a pair of 109Fs that never flew. Estimate performance is sometimes for a version with Jumo 213E engines.

Keep the things simple - carry on with DB 601/605, and forget about the 213.

 

[Zmauky]

Thanks wuzak, Brabazon is a real example that I forgot about. But only about the He 177.
There were a couple of designs (and even one of the early sketches for the P-38) for a variant of the engine in the fuselage and transmission to the propellers on the wings. None of them were realized - were the 1930s a bit too early technologically?
Actually, let's digress a bit (but we're still talking about twin-engine motors/planes ) how many / were there any problems with the DB606 engine or installation in the He 119, or is the He 177 story just the equivalent of premature operational use like the B-29?
From memory (old Lufhart magazines maybe) there was a project of a fighter (or at least a study of the cross-section of the fuselage, the accommodation of the pilot in relation to the engine) with a DB 606 engine, maybe that would be our answer to at least heavy fighter 2nd generation.