Wankel Engines

[Robert Zambelli]

I have a few of these (both series) and I was wondering if anyone has used them for C/L.

My series I turns a 10-6 wood prop at 10,500 RPM on 5% nitro, 23% 50-50 castor-synthetic.

A bit heavy and thirsty but a really neat sound.

Quite smoky but the instructions call for 16-18% oil. I'll mix up a new batch and cut the nitro down to 3% and the oil down to around 18%.

Bob Z.

[James Lee]

Don Holfelder had one in a scale Wildcat at the Nats yeas ago.....
Jim

[Dan McEntee]

  I never see these anywhere to even make an attempt at buying one just to collect. The OS/Graupner was reported to not exactly be a power house. I had a friend/customer at the hobby shop I worked at named Floyd Cramer that built the worlds first operating Wankel model engine. There was some dispute over it and I provided him with a copy of a mention and photos of his that was in American Aircraft Modeler well before the OS/Graupner unit became available. Floyd showed me an assembled engine and one in pieces in a box years ago at the shop one night. He was a master machinist and made several of his won engines, including a scale model of a Kinner that he used to power a 1/4 scale Kinner biplane, that I was able to see run and fly!! The Wankels were a disappointment to him, as they just never did meet expectations running them on a test stand, so he never tried them on an R/C model. Good luck with this project and let us know how things go
   Type at you later,
    Dan McEntee

[Robert Zambelli]

OK, thanks for replying.

Actually, I was a bit surprised at how fast it spun the 10-6 prop.
It was sitting for around ten years so I gave it a thorough cleaning and lube.
Electric starter required - it started within seconds and shown virtually no vibration and was surprisingly quiet.
One way to see if it works - I'll just bolt it on an old test plane and see what happens.
Keep in mind - one test is worth a thousand expert opinions      

I'll post results.

Bob Z.

[Dan McEntee]

OK, thanks for replying.

Actually, I was a bit surprised at how fast it spun the 10-6 prop.
It was sitting for around ten years so I gave it a thorough cleaning and lube.
Electric starter required - it started within seconds and shown virtually no vibration and was surprisingly quiet.
One way to see if it works - I'll just bolt it on an old test plane and see what happens.
Keep in mind - one test is worth a thousand expert opinions      

I'll post results.

Bob Z.

   Egg zakly!!

   Dan McEntee

[john e. holliday]

I had a Wankel on a Sterling Steerman.   Three line control.  For some reason mine woul start by hand if I would give it a healthy prime.  On high speed its like a racing plane, but it throttled very well and I could do touch and goes as well as taxi.  Like a dummy I let some one talk me out of it.  Sure wish I had it back as it was a lot of fun for me and the spectators.

[bill bischoff]

Back in the 70's, Charlie Bauer had a pair of them on a CL scale Grumman F5F Skyrocket. I never saw it fly, but pictures of in were in one of the Harry Higley books.

[Motorman]

I would use 20% castor to try and preserve the seals and control the heat. Two problems these were know for. Let it smoke.

[Jeremy Chinn]

I remember a friend running one in the late 80’s. I remember it being very thirsty and running very hot.

[Robert Zambelli]

I remember a friend running one in the late 80’s. I remember it being very thirsty and running very hot.

CORRECT on both counts!

[John Miller]

I built a Sheiks Staggerwing Beech in the late 90's. I powered it with an OS. Wankle .30.  I ran it on 10% all castor, 28%, though I suspect it would have been fine on 50/50 castor/synthetic. It did run hot. It baked on the castor on the outside, so it needed cleaning often. As for power, it was fine for the model it was on, flying the entire pattern with 4 ozs of fuel. Great sound to boot.

I was really foolish for selling that engine, wish I still had it.

[Robert Zambelli]

Well, I finally got to setting up my Circus King with the OS Wankel engine.
I sawed the nose off the Circus King, mounted a firewall for the Wankel and flew it yesterday.
To say I was amazed is an understatement!
I used a 10-6 wood Sail prop, Brodak 5% nitro, 23% 50/50 lube and 62 foot lines.
The plane took off like a rocket and flew 3.85 second laps, pulled like a horse!
It flew much faster than with the original engine, a Johnson 35, which ran on 10% nitro.
The turns were a bit sluggish due to being a bit nose heavy but once I balance and slow it down a bit, it should be a good sport plane. AND, the sound was great.
I designed and installed an adjustable throttle control which should help, along with a lower pitch prop.
I welcome any thoughts comments or suggestions.
Bob Z.

[Dan McEntee]

   Two things I would change. One is it looks like the muffler is cramped against the fuel tank. Make sure you have some air gap there, at least put a 1/8" piece of balsa between them to insulate the tank from heat creep. The second is to close off the throttle to about 2/3 throttle to give you some choke on the engine and then adjust the needle as needed.. it will help with slowing it down If there were such a thing as a C/L venturi for that engine it wouldn't have a throat that big.
  Continue with having fun!!
  Dan McEntee

[Joseph Lijoi]

Well, I finally got to setting up my Circus King with the OS Wankel engine.
I sawed the nose off the Circus King, mounted a firewall for the Wankel and flew it yesterday.
To say I was amazed is an understatement!
I used a 10-6 wood Sail prop, Brodak 5% nitro, 23% 50/50 lube and 62 foot lines.
The plane took off like a rocket and flew 3.85 second laps, pulled like a horse!
It flew much faster than with the original engine, a Johnson 35, which ran on 10% nitro.
The turns were a bit sluggish due to being a bit nose heavy but once I balance and slow it down a bit, it should be a good sport plane. AND, the sound was great.
I designed and installed an adjustable throttle control which should help, along with a lower pitch prop.
I welcome any thoughts comments or suggestions.
Bob Z.

You shouldn’t be surprised. Wankels are known for power to weight ratio and putting out a lot of torque with a smooth power bands. They are also known for poor fuel consumption and excessive emissions, They used to dominate SCCA class racing (Mazda MX3 and MX7) and were known for durability in a racing environment.
I knew a guy who had a choice between opening a Mazda dealership or a Honda dealership. Those were the days when Japanese cars were just hitting the market. He chose Mazda because they had the rotary engine. He thought it was the future.

[Robert Zambelli]

Good advice, Dan - I appreciate it.

First off, there is a substantial gap between the muffler and tank. Also, even if it touched, the contact patch would be so small that any conductive heat transfer would be minimal if any.

Secondly, I have already built in a throttle adjustment device to dial down the power.

Bob Z.

   Two things I would change. One is it looks like the muffler is cramped against the fuel tank. Make sure you have some air gap there, at least put a 1/8" piece of balsa between them to insulate the tank from heat creep. The second is to close off the throttle to about 2/3 throttle to give you some choke on the engine and then adjust the needle as needed.. it will help with slowing it down If there were such a thing as a C/L venturi for that engine it wouldn't have a throat that big.
  Continue with having fun!!
  Dan McEntee

[Robert Zambelli]

Check out the video taken by Mike Lindler!