What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Rotax in an RV-8?

V

viper2fly

I'm New Here
Hey all,

This is probably a huge newbie question, but here goes...

Is it possible/practical to use a Rotax engine (unsure of model) in an RV8 that would give you similar (if not better) performance as comparible to the IO-360 that seems typical? Is it more cost effective? I am sure that as with most things there are many pros and cons from ethier side of the fence.

My curiosity was peaked when I saw an FPNA (Float Planes and Amphib"s) Cape Town (granted light sport catagory and all) that was getting some incredible performance with (usually cheaper) MoGas, and was informed that they have a 6 cyl. model that might be an attractive option.

I realize that I may be putting the cart way before the horse here as I am still trying to find a way to fund my entry into this amazing world of RV's.

Thanks you in advance for your time and replies!

Keith G.
 
I'm also just an RV-wanna-be, but I don't believe there are any rotax aircraft engines suitable for the RV8. The most powerful I know of is the 914 that makes 115hp and weighs under 200lbs IIRC. You would need a very long engine mount to get the weight and balance correct.

The performance would be quite terrible I fear. Even with less weight, going from 200hp down to 115 isn't going to provide very satisfactory results.

If you want a rotax powered RV, the RV-12 is the plane for you:)

I've never seen a 6-cyl rotax production aircraft engine. I also didn't see one listed in the kitplanes directory. Perhaps you are thinking of the 6-cyl jabiru? If so, the same applies as its only 120hp. Jabiru did make an 8-cyl that has on rare occasion found its way into an RV, though I think there have been some issues with it and am not sure it is currently in production.

You can build a lyc to run on mogas without problems. The general rule of thumb is a compression ratio of 9:1 or less. With the new IO-390 from lyc you can run mogas and still make all the power the airframe was designed for.
 
Last edited:
low aspect ratio wing needs more power

The basic problem is that the low aspect ratio wing is not efficient enough to get by with such low power. You might look at the RV-9 as a possibility - I think it would be OK with 115 hp.

Otherwise, for the -8, you better find an engine with at least 160 hp.
 
scsmith said:
The basic problem is that the low aspect ratio wing is not efficient enough to get by with such low power. You might look at the RV-9 as a possibility - I think it would be OK with 115 hp.

Otherwise, for the -8, you better find an engine with at least 160 hp.
Click to expand...

Since we are brain storming here and you are an AE how about a -8 twin? Twin Rotax 912S 100HP? The wings are not really designed to handle that kind of weight. Obviously, this would require some serious mods.
 
Last edited:
If you're going to mention a twin engine rv-8 then we might as well go back to talking about an f-82 style mod :D
 
There is actually an airplane out there like this

It's called a Tecnam P2006T.

It uses two Rotax 912s (100hp each). Runs on Mogas and cruises at 145kts on 10gph.

Italian built, mostly composite and certified. $500k I think.

There is one at a local airport here in VA.
 
Besides the expected poor performance from that small HP number on a plane designed for between 150 to 200 hp, there is that CG thing you have to think about.

There is a thread on here about putting that engine on an RV-3 (designed for 108 to 160 hp) and the rough calculation was that the engine mount would have to be extended another 20".

Keep dreaming, that?s how new designs come about.

For comparison, look at the T51 Mustang. It is about the same size as the -8 but runs the Rotax engine.
 
TWIN RV8...excellent idea!!!!!

Hey Y'all,

I am always amazed at the amount of knowledge that exisits in the RV community...I am humbled...

I am no where near an aeronautical engineer, and I have very limited experience in this area...so I intend to spend some time leaning on the kind folks in these forums. Thank you!

Keith G.
RV8 or maybe RV10 Wanna be builder!
 
Comanchero!

I have a friend that started a twin 8 with twin comanche wings/gear. He ran some computer modeling that said it would work, so he bought wings & such and started cutting off the spars. And there it sits. Anyone need a pair of T-commie wings with short spars? He really did have some nice drawings though.
 
Now that sounds cool.

I'd rather have the TwinCo, but if you just had stub wings, with a rocket or -8 fuse, and retractable gear...


:)
 
a V300T would sort the power problem adequately...

V300T.jpg


...if only they made one!
 
The PHILIPS SPEED TWIN looked like an RV-8 with 2 engines.
It was a plans or kit build plane available about 25 years ago.
Designed by a British military test and acro pilot, it was a remarkable plane.
It was powered by Continental O-200s, and is a taildragger.
It's also a Dam**d good looking mount.
When Mr Philips died, his wife and Co. withdrew it from the market to 'improve' it with larger engines etc. etc. then dissapeared.
I've been trying to find out how to contact them...I'd like to buy plans for the original. It's as close as you would ever get to an RV-8 twin, and it was fully certified as a british homebuilt, test flown with pilot reports and everything. There was a full spread in Kitplanes, which I read every now and then.
Van probably knows all about it...I only dream he would make the kit.:cool:
http://www.glue-it.co.uk/aircraft/phillips/speed twin e2e/index.html
 
Kevin;
Is there anything we could do about it?
I'm getting near the finish with my RV-8....the Speedtwin would be the ideal follow up project.
 
SHIPCHIEF said:
Kevin;
Is there anything we could do about it?
I'm getting near the finish with my RV-8....the Speedtwin would be the ideal follow up project.
Click to expand...
I don't see much chance that the design will ever be produced as a kit. It would have a fairly small market, so you wouldn't have many sales to amortize the fixed costs over. This would drive the kit cost quite high, and if you add in the need to buy, feed and maintain two engines it would be much, much more expensive than an RV.

The only possible hope for the design, I think, would be as a plans-built. I.e. whoever owns the design now sells plans. I can't see that much money would be made, but someone might be interested in seeing Peter Phillips' project carry on as a memorial.
 
Speed Twin

My friend Curtis Nielson has purchased the prototype Speed Twin and it it currently residing on the Grand Prairie airport (GPM). It was damaged a few years ago in a hangar accident and is currently in a lot of pieces. Curt is working on rebuilding the airplane and investigating potential future developments. I suspect that he is still a few years out from any kit or plans availability, but if you folks are really interested I will find out if he is willing to release any contact information.

Pat
 
The problem with a 100 HP each side Twin Aircraft

Is that after an engine failure, the remaining engine has just enough power to fly you to the crash site.
 
Pat, I AM interested in the Speedtwin, so a contact would be appreciated.
As far as two engines; 100 Hp each equals the same as an IO-360 RV-8, yet the single engine out ceiling was something like 4 or 5 thousand feet (edit: it's 3 thousand feet) even though the props don't feather? That equates to a very long glide, even if one quits in the Cascade mountains. Over Puget Sound, no ditch.
It's a personal thing, anyway, isn't that why we build?
 
Last edited:
SPEEDTWIN

Here's a pull from the atricle:
Phillips decided on twin engines for power and redundancy. He flew Gloster Meteors in the Royal Air Force, and later performed air displays with them. He liked the flexibility that the Meteor's twin engines gave him for his aerobatic routine. Further, after leaving the RAF in the early '60s, he demonstrated a number of multi-engine aircraft, including the twin-engine Islander and the three-engine Trislander for Brittan-Norman.

In 1981, Phillips started to design a personal aircraft with uncompromised handling and visibility. At the time, he was the chief test pilot for the Norman Aeroplane Company. NAC was engaged in developing and certifying the innovative Firecracker military trainer, the very large Fieldmaster AG plane and the Freelance touring aircraft.

In 1988, just before the NAC went out of business, Phillips and his wife, Sue, moved to the Upper Cae Gawr Farm deep in the Welsh sheep country. Phillips put up a building where he and his team of designers and engineers could develop his new design. Over the next four years, the Speedtwin and its proprietary remote aerodynamic power (RAP) system became a reality.

Meet the Speedtwin

Phillips chose the tandem-seating arrangement to minimize drag, but he fashioned the cockpit to be wide enough for comfort, and he raised the rear seat to enhance visibility.

His memories of the Meteor's twin-engine aerobatic capabilities confirmed his choice for an extra engine. But unlike the Meteor, he brought the engines in close to the fuselage to reduce the effects of asymmetrical thrust should one engine be shut down. A clean tailwheel landing gear system reduces drag--with the maingear Oleos and wheels carefully faired.

The aircraft structure is all-metal, fully corrosion proofed, and flush riveted; it is as light and simple as possible to make things easy for the homebuilder. In fact, the Speedtwin was conceived as an assembly of quick-build components. It is not a simple build, but the quick-build subassemblies and complete component package
 
Geico266 said:
Since we are brain storming here and you are an AE how about a -8 twin? Twin Rotax 912S 100HP? The wings are not really designed to handle that kind of weight. Obviously, this would require some serious mods.
Click to expand...

There was a cozy, that was built as a twin with two Suzuki 100 hp four cylinder engines powering two counter rotating propellers on a common shaft. The two engine were mounted in the engine compartment built for a O-360. " Two of the 100h.p., aluminum block, four-cylinder, inline, liquid-cooled, 1,600cc engines were purchased new for $2,200 each."


motor_2_grande.jpg

Cozy%20atardecer%20002.jpg
 
Last edited:
yak53 said:
There was a cozy, that was built as a twin with two Suzuki 100 hp four cylinder engines powering two counter rotating propellers on a common shaft. The two engine were mounted in the engine compartment built for a O-360. " Two of the 100h.p., aluminum block, four-cylinder, inline, liquid-cooled, 1,600cc engines were purchased new for $2,200 each."


motor_2_grande.jpg

Cozy%20atardecer%20002.jpg
Click to expand...

That plane also flew quite well with those engines. The brothers that own it flew it to Oshkosh from Venesula. SIC
 
At SnF last year I met the test pilot who flew the Bombarder V6. They used a Murphy Moose for the test bed and after the testing he put the M14 radial on it.

He said the engineers had tested the Bombarder V6 on a test stand for ?thousands of hours? and that it was ready to go.? All he had to do was test fly it. None of the engines lasted more than 10 flight hours. The engineers went crazy trying to figure out why it would work in the test cell and not on the plane. Eventually Bombarder dropped the project.

What a bummer! Who knows, they might resurrect it at some time in the future. I sure hope so.
 
SHIPCHIEF said:
Here's a pull from the atricle:
Phillips decided on twin engines for power and redundancy. He flew Gloster Meteors in the Royal Air Force, and later performed air displays with them. He liked the flexibility that the Meteor's twin engines gave him for his aerobatic routine. Further, after leaving the RAF in the early '60s, he demonstrated a number of multi-engine aircraft, including the twin-engine Islander and the three-engine Trislander for Brittan-Norman.

In 1981, Phillips started to design a personal aircraft with uncompromised handling and visibility. At the time, he was the chief test pilot for the Norman Aeroplane Company. NAC was engaged in developing and certifying the innovative Firecracker military trainer, the very large Fieldmaster AG plane and the Freelance touring aircraft.

In 1988, just before the NAC went out of business, Phillips and his wife, Sue, moved to the Upper Cae Gawr Farm deep in the Welsh sheep country. Phillips put up a building where he and his team of designers and engineers could develop his new design. Over the next four years, the Speedtwin and its proprietary remote aerodynamic power (RAP) system became a reality.

Meet the Speedtwin

Phillips chose the tandem-seating arrangement to minimize drag, but he fashioned the cockpit to be wide enough for comfort, and he raised the rear seat to enhance visibility.

His memories of the Meteor's twin-engine aerobatic capabilities confirmed his choice for an extra engine. But unlike the Meteor, he brought the engines in close to the fuselage to reduce the effects of asymmetrical thrust should one engine be shut down. A clean tailwheel landing gear system reduces drag--with the maingear Oleos and wheels carefully faired.

The aircraft structure is all-metal, fully corrosion proofed, and flush riveted; it is as light and simple as possible to make things easy for the homebuilder. In fact, the Speedtwin was conceived as an assembly of quick-build components. It is not a simple build, but the quick-build subassemblies and complete component package
Click to expand...




Heya the Philiphs Speedtwin is alive and well , Google speedtwin developments
It has been re-engined with 2x 200hp lycomings and is being test flown right now , It climbs like a home sick angel , and handles like a twin engined chipmunk

Will B-H
 
You must log in or register to reply here.
Back
Top