Fokker D.XXIII, Marton X/V & Other Push-Pull Aircraft

[Mossie]

I'm intrigued by these two aircraft that are very similar & quite probably related, although I've never been able to find much in the way of information on either of them to confirm it one way or the other.

First, Fokker D.XXIII, push-pull fighter developed in The Netherlands in the late 1930's, first flew in 1939.  Only flew four hours of testing before Holland was invaded, so there was never a chance for this aircraft to be proven.  Some say that it was instrumental in inspiring the development of the Do.335, others point out that Dornier had already used tandem mounted engines on several of their flying boats.

A number of engines were slated, the Hispano-Suiza 12Xcrs, Junkers Jumo 210G and Rolls-Royce Kestrel X but the Walter Sagitta I-SR was selected, probably because it was indigenous & Hollands neutral stance at the time.  Rolls Royce Merlin, Daimler Benz DB.601 & Isotta Fraschini Delta were also proposed.

PACOPEPE's winning entry for the Flying Boat GB
General data on Aviastar
Article from Flight including proposed engines
Cutaway from Flight
Detail shots of the Fokker D.XXIII
Pics on Airwar.ru

Models can be found in 1/72 from Pegasus & RS.



Simon

[Mossie]

Next up, Marton X/V (also known as the Varga RMI-8).  Built in Hungary, it used two Daimler Benz DB.605's at 1475hp each.  It was very close in design to the Fokker D.XXIII, details differed such as the wing design, but the layout was very similar.  The main difference was in power output, the Marton X/V having nearly three times the power of the Fokker D.XXIII with two Walter Sagittas at 545hp each.

There is a 1/72 resin model by RS Models.

Excellent build by slava_trudu
http://www.whatifmodelers.com/index.php/topic,24457.0/highlight,marton%20x%20v.html
Wiki article translated from German
Small amount of info on Secret Projects

[Green Dragon]

Both great looking planes Mossie, been meaning to get some kits to go with my Heller Saab J21's. Might have to try bashing a couple of Bf109's into a Marton lookalike.

Paul Harrison

[Weaver]

I've got three Pegasus Fokker D.XXIIIs in the stash. Pencilled-in plans are:

1. Real World
2. In Finnish service with winter cammo and retractable skis from a SMER Hi-Tech Plus I-153,
3. In Spanish Republican service

[NARSES2]

I've the RS resin kit of the Marton, very nice kit. May have to pull it from the stash once the current crop is in. Fancy some resin for a change 

[McGreig]

And let us not forget the Moskalev SAM-13, Comrade!

Unlike the Marton developed by the fascist running dog Hungarians (in the days, of course, before they became the valued-socialist-ally-and MiG-customer Hungarians ), the SAM-13 actually flew.

It was undergoing flight testing at LII and had been entered in the summer 1941 high speed race when the Germans, panicked by the thought of a Soviet air racing victory, invaded on 22 June and forced the abandonment and destruction of the aircraft 

[Mossie]

Ah, nice addition McGreig!  I like the single vertical fin, very unusual.  Is there any evidence that the Moskalev & Marton are related to the Fokker?  Are they just inspired by the D.XXIII, or did the Germans pass on information to the Russians (quite possible early in the war) & Hungarians?  Also, does anyone know what testing the Germans did with the D.XXIII & if there's any pics of it in Luftwaffe markings?

[famvburg]

   There's also the Fokker D-XXXIII derived Mitsubishi Type 0 seen at the Hikoki 1946 site. http://www.j-aircraft.org/xplanes/

[McGreig]

Don't know about the Marton, but the SAM-13 is not directly linked to the Fokker. However, it appears almost certainly to have been inspired by it. It's design was started by Moskalev in 1938 immediately after the D-XXIII had been exhibited at the Paris Salon and it was first flown in August 1940, eighteen months after the Dutch aircraft.

(Although this sequence of dates did not stop the (usually reliable) Soviet aviation historian V.B. Shavrov claiming that "Fokker designed an almost exact copy of the SAM-13 - - - ")

[Mossie]

   There's also the Fokker D-XXXIII derived Mitsubishi Type 0 seen at the Hikoki 1946 site. http://www.j-aircraft.org/xplanes/

Excellent, another great find!  This one appears to be an actual copy or licensed design.  Seems it was given the code name Harry.

I realise the pic is an artists impressions, but a the ear intakes seem to be a way of increasing the air into the rear engine.  Probably not as important on a radial, but might have been away of increasing the airflow to the rear engine, something that Fokker found to be a problem.  I'd personaly site them lower or dorsally so you wouldn't have to remove the rear window & restrict vision.

Pic pulled from above link:

[Mossie]

While I'm on the subject of the cooling problems to the rear engine on the D.XXIII, I think the side & front view illustrates the problem pretty well.  The forward oleo & doors are right in front of the intake & would probably disturb much of the airflow into it on take off & landing.  These are the times when you need as much air flowing as possible due to reduced air speed & extra stress on the engine.

So how might you go about increasing cooling?  Increasing the size of the venral intake might help a bit.  Ear intakes like the diagram of the Mitsibushi Type 0 might help, but would require the removal of the rear windows, reducing rear visibility.  Siting these lower might be an answer.  Intakes in the leading edges are out, as the ammo feed to boom mounted cannon feeds through here from the fuselage, although you could mount them under the wings like the Bf-109 or Spitfire.  A dorsal intake is possible.  Another problem was the strong possibility of the pilot striking the rear prop on bail out, maybe it would be possible to engineer a dorsal intake to enable the pilot to slide up it, avoiding the prop?  Probably not, you'd have to assume he's going straight up & not over the side.

Three view taken from the Richard Ferriere site:

[Hobbes]

I realise the pic is an artists impressions, but a the ear intakes seem to be a way of increasing the air into the rear engine.  Probably not as important on a radial, but might have been away of increasing the airflow to the rear engine, something that Fokker found to be a problem. 

Looks to me like those are aircooled, which means the most efficient way of getting cooling air in is an annular intake. Even then, the rear engine would sit downstream of the hot air coming from the front engine.

One way to increase cooling capacity in the Fokker would be Spitfire-style underwing radiators inboard of the booms. This also avoids airflow problems when the gear is down. 

[redstar72]

More detailed drawings of Fokker D-XXIII are here:
http://www.airwar.ru/other/draw2/fokd23.html

What about the Russians - SAM-13 wasn't their (our) first design of this layout. Even in 1916, similar layout was chosen by Igor Sikorsky for his prototype attack aircraft, the S-19 (or S-XIX). The difference was that pilots' cockpits on S-19 were in the booms, and there was nothing between the engines - but the basic layout was the same. S-19 had two Sunbeam engines, 150 hp each. Four prototypes were built.

Next time the push-pull layout appeared in 1931, on the I-12 (ANT-23) heavy fighter. It was a single-seat aircraft with two Bristol Jupiter VI engines (480 hp each), designed specially for Kurchevsky recoilless guns. Despite "ANT" prefix, the I-12 wasn't designed by Tupolev himself, but by TsAGI engineer named V.N. Chernyshev. It was first flown at August 29, 1931, and was tested until September 28, 1932. The results weren't very promising - maximum speed was only 259 km/h, and the aircraft suffered the booms' vibration. Also the weapon suffered a lot of problems. So, the project was cancelled and the building-up of second prototype wasn't finished.

Note that both the S-19 and ANT-23, like the SAM-13, featured a single vertical fin! (To be correct - the I-12 initially was tested with two fins, but they weren't in propeller slipstream and therefore were uneffective during taxiing and ground run).

[redstar72]

And we can add that Anthony Fokker also used the push-pull, twin-boom configuration first time much before the D-XXIII. His very first attempt was the K-I (M.9) aircraft from 1915, with two 80-hp Oberursel engines, pilot's cockpit between them and gunners' stations in the boom nose parts. The booms were, actually, modified fuselages of well-known Fokker E-I Eindecker fighter.

I hope all this isn't offtopic...

[elmayerle]

I realise the pic is an artists impressions, but a the ear intakes seem to be a way of increasing the air into the rear engine.  Probably not as important on a radial, but might have been away of increasing the airflow to the rear engine, something that Fokker found to be a problem. 

Looks to me like those are aircooled, which means the most efficient way of getting cooling air in is an annular intake. Even then, the rear engine would sit downstream of the hot air coming from the front engine.

One way to increase cooling capacity in the Fokker would be Spitfire-style underwing radiators inboard of the booms. This also avoids airflow problems when the gear is down. 

If I was going to improve cooling for the rear engine, I'd go with an underfuselage scoop to direct the cooling air directly at the finned cylinder heads (I believe the D.XXIII used aircooled engines comparable in configuration to US-built Ranger and Menasco engines).  The cowl opening for the forward engine is about as good an opening as you'd want for this engine configuration (aircooled IV-12).  Now, if you fit some good liquid-cooled engines front and back, a whole lot changes.