Rotax tandem engine contra-rotating propeller vs Single IO-540

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_PabloSniper_

Airman
65
83
Sep 25, 2024
Hello everyone!
I hope I am writing this topic in the right area of the forum.
Well, I am an aviation enthusiast, and also of Rotax engines, because I think their power-to-weight ratio is quite interesting, when compared to that of a traditional engine.
That said, I wanted to bring you some information.
Two Rotax 916 engines, for example, together generate 320 HP and are lighter than an IO-540. And besides the weight, they consume less fuel, and can use car gasoline.


This was an example I found on Reddit, but I made a model sketch using AI.





I think it would be very interesting, because with both engines working well, we won't have the effect of torque.
And if one of them fails, an RV-10 could easily find a landing field with only one engine.
Because if the Tecnam P2006T can maintain level flight with only one Rotax 912 running, an RV-10 can certainly do the same.

But the question I came here to ask is the following.
What is the best way to couple these engines?
Does this idea make sense to you?
I posted this in a Facebook group, and I was almost virtually lynched. I hope that doesn't happen again here.
In the topic I mentioned examples like the RV-10, but I think they can be extended to several other models.


PS: I also thought about an RV-10 Push-Pull, with a clean look, similar to a DO-335. But that's a topic for another thread.
 
An interesting concept coupling the engines in the RV-10. I would like to see photos of the installation to get a better idea because from your drawing the cowl would need to be quite deep just behind the prop yet the photo of the RV shows it is quite shallow which would suggest they repositioned the front oil sump further back. And that AI prop would never work.
 
Not AI, so not as pretty, but a simpler concept:

Front engine gets modified speed reducer to accommodate the shaft from the rear engine/the contra-rotating propellers shaft from the front engine.
Rear engine (mounted reversed) gets modified speed reducer as there is no longer a propeller needing to be attached/needs shaft running to the front engine. I added a support at the back (now front) of the rear engine.

The biggest challenge with this mockup - the shaft between the engines will bind as the engines flex on their mounts.
I have some ideas on how to accommodate that, but to do so without losing power/redesigning the blocks on Rotaxes would take some...creativity.​

 
I posted this in a Facebook group, and I was almost virtually lynched. I hope that doesn't happen again here.

Let's be honest, your cocky attitude and snarky replies garnered most of that vitriol.

The overwhelming point of view is "fine, now show some actual engineering". Most don't think it's a viable option, so it's time to put some sweat equity into your proposal and prove it's viability. Do the CAD work then put it in a flight simulator.
 
Let's be honest, your cocky attitude and snarky replies garnered most of that vitriol.
Okay, let's be honest then. Where have I deliberately started a sarcastic debate without being provoked first?
I didn't mean to bring this up here on the forum.
I participate in several forums and have never had any problems.
 
Thanks for the advice, I'll try that.
 
It seems more complicated than I imagined.
 
two short shafts with universal or cardin joints on each end and a centre bearing or just one shaft and leave out the centre bearing/support. Thin wall tube can carry a lot of power without bending
 

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