RV-10 Pfeil and Macchi: The New Era of Experimental Aviation

[=BLW=Pablo]

Hello, gentlemen! I usually come here to make suggestions for tanks and planes for the game. But this time I came to show you a suggestion for a real-life plane. Two models of 4-seater, twin-engine planes, with a purchase cost lower than a normal RV-10. And inspired by two legends of aviation. I hope you like it.

 

 

 

 

 

 

Edited May 18 by =BLW=Pablo

[AndyJWest]

So, how far advanced it the design process? When can we expect to see prototypes flying?

 

 

[=BLW=Pablo]

6 hours ago, AndyJWest said:

So, how far advanced it the design process? When can we expect to see prototypes flying?

 

 

 

Unfortunately, things are not so simple in aviation.
Even more so in an underdeveloped country like Brazil.
But the version with two engines in the front does not require much effort.

 

 

How to install two Rotax 900-series engines and connect them to contra-rotating propellers with minimal work Note: This is a simple, unrefined sketch — not focused on aesthetics — but it clearly illustrates the concept and shows exactly how the setup can be achieved. This system features two Rotax engines mounted face-to-face. The engine on the right (Engine 1) is fixed to the aircraft’s firewall and has an internal shaft (shown in red) that passes through the tubular shaft of the left engine (Engine 2), driving the front propeller — the one farthest from the engines. Engine 2 has an external tubular shaft that surrounds Engine 1’s shaft and drives the rear propeller — the one closest to the engines. Since the engines are mirrored, they rotate in opposite directions, creating a contra-rotating propeller system without the need for gearboxes or transmission mechanisms. To make this design feasible, Engine 2’s intake manifolds had to be modified to allow space for the passing shaft.

[AndyJWest]

Your link doesn't work.

[=BLW=Pablo]

2 hours ago, AndyJWest said:

Your link doesn't work.

 

 

try this

[AndyJWest]

I was referring to the link in your last post. If your idea is to mount the engines like you show in the video (at around 1:14), it looks questionable to me. For that to work, you'd either have to lock the two engines together very precisely, and very rigidly or incorporate flexible couplings in the shaft. You'd need to support the engine (and the propeller shaft bearing) at the front, adding weight.

 

You might also run into overheating problems with the rear engine. As I understand it, these engines have water-cooled cylinder heads, but rely on air cooling for the remainder.  

[=BLW=Pablo]

5 hours ago, AndyJWest said:

I was referring to the link in your last post. If your idea is to mount the engines like you show in the video (at around 1:14), it looks questionable to me. For that to work, you'd either have to lock the two engines together very precisely, and very rigidly or incorporate flexible couplings in the shaft. You'd need to support the engine (and the propeller shaft bearing) at the front, adding weight.

 

You might also run into overheating problems with the rear engine. As I understand it, these engines have water-cooled cylinder heads, but rely on air cooling for the remainder.  

So, developing this might be harder than it sounds.
But it's just a concept.

[AndyJWest]

Honestly, if I was proposing a GA twin with the engines both on the centreline, I'd go with a Cessna Skymaster-type twin boom layout. You shouldn't have the rear prop clearance issues and extra weight of a prop shaft extension a Pfiel-type design has, nor all the complications your contraprop proposal leads to.

 

Burt Rutan, needless to say, took a different approach:

[=BLW=Pablo]

On 5/19/2025 at 12:55 PM, AndyJWest said:

Honestly, if I was proposing a GA twin with the engines both on the centreline, I'd go with a Cessna Skymaster-type twin boom layout. You shouldn't have the rear prop clearance issues and extra weight of a prop shaft extension a Pfiel-type design has, nor all the complications your contraprop proposal leads to.

 

Burt Rutan, needless to say, took a different approach:

 

 

And what would you say about a more traditional approach?

 

 

[AndyJWest]

Well yes, a conventional twin probably works well enough. That particular design looks a little toy-like, but that's probably preferable to just looking like every other GA twin. Your proposals were for two-engines-on-the-centerline layouts though. Much more interesting, even if not really practical. And the world needs innovation...

 

...at least sometimes.

 

Why stop at two engines, when three will add 10% to the speed, and only double the noise levels? 😮

 

 

[=BLW=Pablo]

4 hours ago, AndyJWest said:

 Your proposals were for two-engines-on-the-centerline layouts though. Much more interesting, even if not really practical. And the world needs innovation...

 

Yes, my proposal would be to use two central engines. And I honestly don't understand how this has never been attempted again in the history of aviation.
If you think about it, this was already done successfully at least 80 years ago. Has engineering not evolved enough to make an 80-year-old design reliable?

[AndyJWest]

 

Wild Double Ender: http://www.bushplanedesign.com/the-story.html

 

There's the Rutan designs too. And the Cessna. And at least one flying boat from Dornier in a similar configuration. And more...

 

Regarding aircraft with two engines driving contra-rotating propellers on a common shaft, the Fairey Gannet (a turboprop) worked more or less that way, and sometimes cruised with one propeller stopped to reduce fuel consumption. One could argue endlessly as to whether the Double Mamba power plant was actually one engine or two, but either way, it functioned like two. Whether the Macchi M.C.72 itself was single-engine or twin is again open to debate: there was nominally only one power plant, the Fiat AS.6, but this was two V12s combined as a single unit. The Bugatti Model 100, again with common-shaft contrarotating props, was another one-off, and there was at least one design proposal/prototype for a WW2 fighter in the Macchi layout. Possibly Italian I think? I'd have to search for that one unless anyone else remembers it.

 

I suspect the reason relatively few prop twins take a centerline option is because the conventional layout works well enough, and any benefits to deviating from it are fairly marginal in most circumstances. The most often claimed advantage to the centerline layout is possibly safety, since it minimises single-engine thrust asymmetry - it won't eliminate it entirely, since P-factor etc is still going to be present with one dead engine. Added safety was apparently the reasoning behind the Rutan Defiant, which I showed earlier. 

 

Edited May 21 by AndyJWest