Twin engine contra rotating prop

[Reno_Steve]

Rather than trying to squeeze extra power out of the engines, why not design the aircraft to use two engines , one behind the other combined with a contra rotating prop or a prop at the front and another at the back

Would this be allowed within the Sports class ?

Has it been tried in the Unlimiteds.

[Red]

Re: Twin engine contra rotating prop

Like this?

http://www.landings.com/evird.acgi$pass*95244913!_h-www.landings.com/_landings/pacflyer/jul5-2007/Jl-70-dave-roses-roc.html

(you'll have to cut n paste-can't get it to hyper link)

[supercub]

Re: Twin engine contra rotating prop

What's the status with the RP 4?

[Peashooter]

Re: Twin engine contra rotating prop

Or the MC-72:

http://www.aviationtrivia.info/Macchi-Castoldi-MC-72.php

Note the date of the record! It still stands...

Good idea -- got some money?

[Skyracer]

Re: Twin engine contra rotating prop

Or the MC-72:

http://www.aviationtrivia.info/Macchi-Castoldi-MC-72.php

Note the date of the record! It still stands...

Good idea -- got some money?

From the link: "A shaft from the rear engine ran through the front engine's hollow crank shaft and on through it's hollow drive shaft to power the front propeller in one direction."

Hmmm...That must have been interesting!

[W J Pearce]

Re: Twin engine contra rotating prop

Rather than trying to squeeze extra power out of the engines, why not design the aircraft to use two engines , one behind the other combined with a contra rotating prop or a prop at the front and another at the back

Would this be allowed within the Sports class ?

Has it been tried in the Unlimiteds.

Like the Do 335 or the MC72?

Yes it would be allowed in the sport class if it was sold as a kit with at least 5 kits sold and the engine was within the limits. Unless there is a new single engine rule but I don't think there is one.

One has never competed in the unlimited but the DG-1 (pull/push like the Do 335) was built and flown in the 70s, but was unstable. Then there is that Griffon/Lear (Do 335 style) rumor that was floated some months ago. RP-4 is similar to the MC72 style, but I don't think it has flown. I can not think of any others.

I think it all boils down to that same issue..... money.

[W J Pearce]

Re: Twin engine contra rotating prop

From the link: "A shaft from the rear engine ran through the front engine's hollow crank shaft and on through it's hollow drive shaft to power the front propeller in one direction."

Hmmm...That must have been interesting!

That's wrong. The MC72 was powered by a FIAT AS6 V24 which, oversimplified, were two AS5 V12 engines back to back. The rear engine drove a shaft through the "V" of the front engine. This shaft was geared to the crank off the rear engine and that is where the gear reduction occurred for the rear engine, between the two. The front engine has it's reduction right off the crank then the shaft from the rear engine went through that, all with spur gears. The front engine drove the rear prop, the rear engine the front prop. The second engine drove the supercharger that fed both engines. The pitch for the the props was ground adjustable and the front and rear were adjusted to different pitches to compensate for the supercharger drain on the second engine (front prop) as well as efficiency differences between the first and second set of blades.

The second engine did not run a shaft through a hollow crank in the first.

http://www.preservedaxisaircraft.com/Italy/images/FIAT_AS6.jpg

[Low-n-Slow]

Re: Twin engine contra rotating prop

... two Fiat V-12 engines were linked together, one behind the other. A shaft from the rear engine ran through the front engine's hollow crank shaft ...

Wow, always been impressed with Italian motorsport engineering, but I gotta admit, running a 1200 HP contrarotating PTO shaft through a hollow crank is a trick that staggers the imagination

cheers
Scott

[Peashooter]

Re: Twin engine contra rotating prop

Wow, always been impressed with Italian motorsport engineering, but I gotta admit, running a 1200 HP contrarotating PTO shaft through a hollow crank is a trick that staggers the imagination cheers
Scott

"Talkin' 'bout 'Shaft'!"

[W J Pearce]

Re: Twin engine contra rotating prop

That's wrong. The MC72 was powered by a FIAT AS6 V24 which, oversimplified, were two AS5 V12 engines back to back. The rear engine drove a shaft through the "V" of the front engine. This shaft was geared to the crank off the rear engine and that is where the gear reduction occurred for the rear engine, between the two. The front engine has it's reduction right off the crank then the shaft from the rear engine went through that, all with spur gears. The front engine drove the rear prop, the rear engine the front prop. The second engine drove the supercharger that fed both engines. The pitch for the the props was ground adjustable and the front and rear were adjusted to different pitches to compensate for the supercharger drain on the second engine (front prop) as well as efficiency differences between the first and second set of blades.

The second engine did not run a shaft through a hollow crank in the first.

http://www.preservedaxisaircraft.com...s/FIAT_AS6.jpg

Correction here. the gear reduction for both engines occurred between them. Both had shafts that were in the V of the front engine. The rear engine's shaft was inside of the front engine's shaft.

Sorry about the confusion. I was looking at a schematic of the patent that was filed for the drive system but was not what was actually used on the AS6. My fault for not paying attention.

Because the engines were back to back, both drove the props off the their respective "back" which was in the middle of the AS6.

[440_Magnum]

Re: Twin engine contra rotating prop

Wow, always been impressed with Italian motorsport engineering, but I gotta admit, running a 1200 HP contrarotating PTO shaft through a hollow crank is a trick that staggers the imagination

cheers
Scott

Yeah, especially the way the connecting rods have to break and then re-weld themselves every turn of the front engine crank....

[Skyracer]

Re: Twin engine contra rotating prop

Yeah, especially the way the connecting rods have to break and then re-weld themselves every turn of the front engine crank....

Maybe they ran a flexible shaft (really heavy duty speedometer cable) through the hollow crankshaft. He he!!!

[Peashooter]

Re: Twin engine contra rotating prop

Yeah, especially the way the connecting rods have to break and then re-weld themselves every turn of the front engine crank....

http://www.youtube.com/watch?v=tZzBrxj-Gjo

[Lowell]

Re: Twin engine contra rotating prop

What about the Bugatti Model 100 with the two 450 hp Bugatti type 50B straight 8's of about 1937-40. Displayed at EAA Museum.

Air Progress Oct 73 p.40-49,77; Sport Aviation Sep 96 p.12-13; Sport Aviation Aug 97 p.10-11; Pacific Flyer Feb 01 p.A38;

Somebody was said to be considering a flying replica.

[Reno_Steve]

Re: Twin engine contra rotating prop

Yeah, especially the way the connecting rods have to break and then re-weld themselves every turn of the front engine crank....

With a short stroke engine it should be possible to have a shaft through the front crank. I am not sure whether this has ever been done.
Sorry did not get a chance to look at the Youtube video if this is relevant. Its blocked here.