Hey all,

Currently running a wankel and love the engine, but not getting into the listed rpm that are listed for the engine. I'm currently only hitting in the high 11000 to low 12000 range. I currenty have a 10x6 prop on it, but am not sure about the correct size to swing. I am unable to find any listings on it. Anyone know the correct size?



Thanks all,


Scott J. Wolke

Scott,

The recommended prop size for this engine is a 9x5~6, 9.5x5, or a 10x5. Of course the 9x5 will get you in the high rpm, however it will suck approx. 2oz./min. of fuel. Go to www.os-eingines.co.jp and print or download the manual.

I have two of these and haven't yet flown them. I just picked up a Pica .26 size P-51 kit. The engine fits inside the cowl but not all the way forward. I plan to mount the engine on the firewall and manufacture a prop hub extension. The Sportsman Aviation Waco .30 ARF biplane probably would have been a better choice considering the light wing loading to carry extra fuel and the engine fitting inside the cowl without any modifications. I'll give it a shot anyway. If the old lady lets, I might get the Waco to put the other engine in.

What do you plan on mounting the engine on?

can you give me any and all info on the os wankel plz i'm working on a conversion of my own but for an Rc car and any info i can get from an actuall wankel owner tell i get my engine would help out tons...... thank you

I'm not sure it will work in a car unless you devise some type of cooling fan. These engines run very hot. The first generation os wankels had a shroud around the perimeter of the engine to help with cooling. It did not work too well. The second generation is designed with better cooling properties, however it still runs hot. For instance, I did put the other engine in a Sportsman Aviation .30 Waco ARF and had to add a length of silicone exhaust tubing to get the muffler outside of the cowl. The heat generated at the exhaust port would split the heavy gage tubing after three 8 min. flights. My solution to this problem was to machine an aluminum exhaust manifold with cooling fins. No muffler involved, just a straight pipe. The engine runs cooler, sounds mean, and has instantaneous throttle response.

Another thing is they suck a lot of fuel (2 oz./min. @ full throttle) and like at least 20% nitro with 20% Castor/synthetic oil or 25% pure Castor. No need for a smoke system, they leave a nice trail at 1/2 throttle when the mixture is correct.

Something else to consider, they do not work well with a pressurized fuel system. They suck so much fuel, it is not necessary. Plus the carburetor is without a low end mixture control. It does have an air bleed to help out at idle but it is just a hole in the venturi, no adjustment. It does idle well after break-in and with a heavy prop. An APC prop is heavy enough to act somewhat like a flywheel and it will idle down low, however not a sustained idle. It loads up when the fuel tank is full and idles better when the tank is low. So at take off with full fuel, your rich on the low side and when you land with low fuel your low end mixture seams to be just right to get a low sustained idle. It took a while to figure this out. In other words, with the right type of fuel, the right prop, and the proper mixture, they run perfectly without any further adjustment. If a different prop is installed or a different type of fuel is used, it will take a little trial and error to get it just right again.

The Waco/Wankel combination is awesome. Ground handling at take off is horrible. So the key is to just advance to full throttle and hold on. The plane is air born in about one second.

Put it in a car? I would suggest you could go a little crazy trying to convert it. I'm speaking from experience when it comes to engineering the unusual. You might be better off taking a car engine and doing some performance upgrades.

I love my two engines very much, they are little jewels of engineering excellence. If you go to the O.S. web sight, you can download the manual on the .30 Wankel.

I do have a crazy idea of converting an Arctic Cat snow mobile engine (200cc, two rotor Wankel) to fly my 1/4 scale Bud Nosen F4U Corsair. If I survive the conversion, I'll put on RC Universe.

Good Luck.

i only have one thing to say to all that

also thnx for the info it helps out a ton and i have had the manula that is helping designs run smoother also aren't we all a little crazy but i have had this project in mind for a good long time now and untell the motor blows up in my face i'm not giving up on it lol but now i need to go weigh that prop and designe a flywheel the proper wheight....you don't happen to now what it weighs do you.....by the way if you haven't noticed i'm a rotory nut so yeah this is a project to make a car that will match my actuall 7



oh and a video of the engine running would be awsome or even just a sound byte of it so i can get an idea of the exact sound thx

A guy here had one of those on a .40 size stick. It pulled it very well.