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

[McGreig]

the I-12 (ANT-23) heavy fighter - - - was a single-seat aircraft with two Bristol Jupiter VI engines (480 hp each), designed specially for Kurchevsky recoilless guns.

It's not for those easily shocked, or of a nervous disposition, but Unicraft produce a resin kit of the ANT-23 - - -

[redstar72]

Elmayerle, you are right: the Walter Sagitta engines used on the D-XXIII were air-cooled.

It's interesting that Alexander Moskalev himself recollected that he didn't know about the D-XXIII when designing the SAM-13! According to his memoirs The Blue Spiral, he found out the Fokker only at wartime - and was very surprised by such a concurrence of design ideas (http://www.airwar.ru/enc/fww2/sam13.html).

[redstar72]

It's not for those easily shocked, or of a nervous disposition, but Unicraft produce a resin kit of the ANT-23 - - -

Yes, they do, but... it looks so terrible! (The kit, I mean, not the aircraft ). And they want $30 for this!


http://www.unicraft.20m.com/on/ant23/ant23.htm

And what's interesting: the kit is a "whif-in-a-box"! The wings are quite different from those with clipped wingtips and corrugated covering from the ANT-23 that actually flew. Are they mean the uncompleted second prototype (ANT-23bis)?

[Hobbes]

Elmayerle, you are right: the Walter Sagitta engines used on the D-XXIII were air-cooled.

That's quite a surprise; I don't think I've seen an aircooled V-12 before. Cooling the rear cylinders must have been a nightmare.

[Mossie]

Now, if you fit some good liquid-cooled engines front and back, a whole lot changes.

This is something I've been looking at & finding it difficult to get my head around.  I've did a few profiles some months back with different instalations (I'll post the others later), I've been focsuing on the Kestrel.  I've found it quite difficult to work out how to cool both engines.  Surely intakes front & rear inline with one another would interfere?  Also, as you introduce more powerful engines such as later versions the Merlin, the cooling requirements increase & becomes more difficult to fit things in.  Would you be able to use a single intake to cool both engines?




I pretty much thought it wouldn't be possible to put in larger engines in this aircraft without completley redesigning it, but this idea was pretty much knocked for six when I discovered the Marton X/V.  It has two DB.605's & only a single small intake in an airframe of very simillar size & configuration to the D.XXIII.  It didn't fly, so we don't know if there were potential problems.  I've noticed the DB series tends to have smaller radiators than the RR inlines, is this beacuse it needed less cooling, or better radiator design?  Or am I missing something???

Slava_trudu's build shows the configuration of the X/V pretty well:
Marton X/V build by slava_trudu

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. 

I've just looked at the underside diagram on the link Redstar provided, it might be difficult to get Spitfire style radiators into this spot.  The landing gear crosses right across the middle, cutting the amount of room available.

[McGreig]

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). 

Interestingly, in Edwin Dyer's recent "Japanese Secret Projects", the drawing of the Mitsubishi TK-4/Type 0 looks much more like a radial engined DXXIII. It dispenses with the ear style intakes on the fuselage side and has a deeper under-fuselage intake than the version on the Hikoki 46 site.

[McGreig]

And if the thread is turning into a free-for-all of push-pull twin boomers, we should include the Tachikawa Ki-94-1. Although this was ultimately rejected (apparently on the grounds of being too unorthodox and too complex to build) it did reach the wooden mock up stage and has been kitted in resin by A & V. (an ideal rehabilitation project for anyone who's still waking up shaking in the middle of the night after attempting a Unicraft kit )

[Mossie]

Modified the thread title to suit.

[redstar72]

That's quite a surprise; I don't think I've seen an aircooled V-12 before. Cooling the rear cylinders must have been a nightmare.

But the Sagitta wasn't unique. The Renault 12Ro1 engine of well-known Caudron CR-714 light fighter was an air-cooled inverted V12. The Italian Isotta-Fraschini Delta used for Ambrosini light fighters (SAI-207, SAI-403 Dardo, and also prototype Caudron C-760) also had the same layout. And another prototype Caudron was CR-770, powered by (also prototype) 800-hp Renault 626 engine, which was an air-cooled, inverted V16 (!!!)


http://www.aviastar.org/air/france/caudron_cr-770.php

[famvburg]

      I first have to admit that I am a long time friend of Igor of Unicraft. That being said, what's so terrible about it? For $30? It looks buildable, yes, with some cleanup, & how many other kits of this model are available? Have other extremely limited run kits been priced? I assure you, even at $30, for the time, talent & materials involved, there's very little profit involved.

It's not for those easily shocked, or of a nervous disposition, but Unicraft produce a resin kit of the ANT-23 - - -

Yes, they do, but... it looks so terrible! (The kit, I mean, not the aircraft ). And they want $30 for this!


http://www.unicraft.20m.com/on/ant23/ant23.htm

And what's interesting: the kit is a "whif-in-a-box"! The wings are quite different from those with clipped wingtips and corrugated covering from the ANT-23 that actually flew. Are they mean the uncompleted second prototype (ANT-23bis)?

[Mossie]

There's a thread for Unicraft kits, please don't hijack this one.

[PR19_Kit]

On the subject of the DXXIII, I built a resin kit of it some years ago, and very nicely it turned out too, but one thing always puzzled me. What's the almost vertical towel rail thingie for that's on the starboard side of the front engine? Piccie below.

While I'm at it, anyone got any suggestions for replacement props for the XXIII? As you can see on the pic 2/3 of the aft prop has pinged off, and I've re-glued the front one more times than a few by now.

[Weaver]

I'm puzzled as to how the Marton cooled it's engines too.....

On the general subject of push-pull cooling, a couple of things occur to me:

1. Four wing leading edge radiators, one on each wing serving each engine: that way, battle damage (unlikely to happen to both wings) doesn't destroy all cooling capacity.

2. FW-190-style "fan-pushed" annular radiator for the front engine, with side exhaust vents. Another "fan-pulled" annular radiator behind the aft engine with a ventral intake that doesn't breath in the exhaust from the front one, and doesn't suffer from prop-wash blanking by the nose gear during taxiing.

[Green Dragon]

On the subject of the DXXIII, I built a resin kit of it some years ago, and very nicely it turned out too, but one thing always puzzled me. What's the almost vertical towel rail thingie for that's on the starboard side of the front engine? Piccie below.

While I'm at it, anyone got any suggestions for replacement props for the XXIII? As you can see on the pic 2/3 of the aft prop has pinged off, and I've re-glued the front one more times than a few by now.

Probably completely wrong but could it be an escape boom, attach a line, bail out and the rail (hopefully!) takes you away from the props. I remember seeing something like it was on the space shuttle, a telescopic boom for bail out.

Paul Harrison

[PR19_Kit]

Paul,

NICE one, yes! 

You would have to be pretty darned careful to clear the rear prop when bailing out for sure, and that rail would guide you clear. All the time I was thinking in terms of some extended oil breather or similar, but the escape rail makes a lot of sense, thanks.