Rotary aircraft engines

[eastmeg2]

Can anyone tell how much more fuel a rotary engine uses compared to a 4-stroke for the same power output, and why?

 

 

[facthunter]

fuel consumption.

 

The wankel Specific fuel consumption, ( Litres/ Horsepower Hour) falls between that of a good two-stroke, and a petrol 4-stroke,( closer to a conventional petrol aero engine than a two-stroke) Not a U-beaut stratified lean burn device.

 

Why?

 

I would say;

 

1. the exhaust has to get out quickly, so the port is big and opens while there is still a lot of pressure. ( hence the noise)

 

2. the combustion chamber has a large surface area/volume, so thermodynamically there is a lot of heat wasted. the combustion chamber is far from optimum shape as regards flame propagation, necessitating two spark plugs per cylinder in most applications.

 

On the plus side, it doesn't appear to need high-octane fuel. The specific fuel consumption figures are easy to obtain with a fuel flowmeter on a dynamometer, but you need accurate (honest ) comparisons. The engines turbo well as far as power goes, but obviously the case distortion and fuel consumption figures would be another matter, then.

 

Nev.....

 

 

[Guest Stickman]

From what I've been able to determine, over researching aircraft applications for rotary engines the last several days, you can expect to lose maybe 10% in endurance, but considering you can use mogas, I think it's a wash. As far as reliability is concerned, I'd personally be more comfortable with a rotary, provided I built it myself. I've been my own mechanic my entire life, and even with what little experience I've had with rotary engines, I'm certain of their superior reliability over any recip engine ever built. 25 years ago that wasn't necessarily the case, but I think it is now. And with the several very honest testimonials I've read from pilots who have seen 2000 hours with their Mazda rotary without trouble, I'm leaning that way myself, when I can afford to put together my own ship.

 

 

[Guest Munger]

A few years ago a Hiperlight II was fitted with a Wankel Rotary (twin). I don't have much info on it...here is a photo taken at Oshkosh.

Its a Global Rotary Power GR-CC402A-Fi ( http://www.rotaryengines.ca/main/aircraft.htm ). They are about US$14k.

 

 

[Guest danda]

Can the rotary run ok on ethanol blended fuel as this seems to be the way we are being forced to go.

 

Don

 

 

[Guest Munger]

Can the rotary run ok on ethanol blended fuel as this seems to be the way we are being forced to go.Don

That is a top question. I have been looking into the whole rotary engine debate for a few weeks and haven't really found anything 'bad' about them. Specific consumption does go up by about 10% compared to a J2200 or 912.

From the specs I have found on the web, rotary engines are 'happy' to run on unleaded gasoline (91 octane??) or mogas.

 

At http://en.wikipedia.org/wiki/Ethanol#As_a_fuel there is a table which suggests that E10 'Gasohol' (90 % gasoline with 10% ethanol) has about 1.1 MJ/L less in energy but a higher octane rating of 93/94.

 

I guess that means that your endurance will be cut by another 3% on top of the 10% less efficiency than piston power. Now it gets complicated: You seem to have less installed weight on a rotary compared to 4 stroke piston engine, you can run cheaper fuel, need to premix fuel and have higher consumption/hp....can anybody work out the figures, or do we need real life experience here??

 

 

[Yenn]

I have been told that you can get access to accident statistics in the USA, which show a less than glowing endorsement for wankel type engines. I havn't looked myself yet, but it may be worth a try.

 

 

[jetboy]

There have been a few reports of engine failures in the US and proprtional to the numbers flying its probably a high rate however they are all initial installations and not volume produced.

 

Because few rotaries have bee sold by any of these companies they have not developed the next step - kerosine/JetA/ diesel fuel use yet. Very dissapointing as most of their websites (typically 3 yrs old) say that option is "under development".

 

The Renesis Mazda engine is a good candidate for JetA - it has injectors much closer to the ports - I'm not sure if that would be enough or does it need a GDI system like the Yamaha? HPDI outboard motor system to make the kero vapourise for spark ignition?

 

Ralph

 

 

[facthunter]

fuels.

 

Avtur, would need to be vapourised, and even though the wankel is not too fussy on fuel octane (anti-knock value) kero has a very low octane rating, perhaps too low, but that wouldn't rule out a blend.

 

....... Yenn the use of the wankel in outboard racing has been extensive (at least with one particular company) who seem to regard potential reliability as one of it's strong points.

 

Norton (as in motorcycles if you are old enough) produce an air cooled aero engine (wankel.) for small planes, which was based on an engine they used in a motorcycle.

 

....... The development is more metallurgical than design refinement. (hard surface treatment on cases, to prevent wear by the seals (Chatter). I must confess I hadn't heard of any unreliability recently. I would like to know what the specific broblem is.

 

The engine nearly sent NSU broke and only Mazda made a go of it, but that is a long time ago, now. Nev

 

 

[Yenn]

Have a look at http://WWW.homebuiltaeroplanes.com. There is a forum on engines and I looked at it yesterday. It has a good post by "Orion" a person whom I would listen to for common sense info. He is enthusiastic about rotary engines.

 

 

[jetboy]

Facthunter, I would have gone with the Norton in its current form on my CH701 if I could. The Norton aero rights were bought out by Midwest rotary and more recently Diamond Aircraft and in 2004 there were 20 or so "in the back workshop" at their Austria facility. I got a PDF from them for the GIAE110R sorry can't attach its 1.7 Meg file pm me if anyones interested, but no price/ availability date, they said they were awaiting completion of certification.

 

There are allegedly 2 13b based builds being done in NZ, a 2 rotor is in a T51 airframe at Hamilton this might have been assembled by the owner it uses the local Autoflight reduction unit and the Kahu gyro outfit is said to be producing 2 and 1 rotor engines

 

At this time the only available proposition does appear to be Rotamax which seems to have as good a history as any.

 

http://www.diamond-air.at/diamondengines+M52087573ab0.html

 

Ralph

 

 

[Guest Munger]

Have a look at http://WWW.homebuiltaeroplanes.com. There is a forum on engines and I looked at it yesterday. It has a good post by "Orion" a person whom I would listen to for common sense info. He is enthusiastic about rotary engines.

Check out this site for info!! Thanks for the tip Ian!

Benefits and drawbacks of a rotary

 

:thumb_up:

 

 

[Guest ozzie]

Rotary at airventure

 

I have some info on this coming in the mail that i will add when it arrives till then here are some photos of it on the stand and fitted to a gyro

 

ozzie