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Engine basics => Engine set up tips => Topic started by: Robert Zambelli on March 20, 2009, 10:02:32 AM
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I'm evaluating the new OS Wankel for CL scale use.
It's not fully run in yet but it swings a 10-4 prop at 12,000 RPM. ~^ ~^
Anyone had any experience with these gems?
I have both the old and new versions - WHAT a DIFFERENCE!
Nothing like a new Wankel. LL~ LL~
Bob Z.
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Hi Bob I think Charley Bower has used a couple before. You might find him in the scale forum. See ya John
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I'm evaluating the new OS Wankel for CL scale use.
It's not fully run in yet but it swings a 10-4 prop at 12,000 RPM. ~^ ~^
Anyone had any experience with these gems?
I have both the old and new versions - WHAT a DIFFERENCE!
Nothing like a new Wankel. LL~ LL~
Bob Z.
Is the wankel smoother than a comparable size recip? What is the weight?
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It is so smooth it's rediculous - feels like an electric motor.
It's a tad heavy but to be sure, I'll get some comparison weight figures as well as some photos.
Since it's a .30 CID, I'll compare it to a SAITO .30 and a .30 CID 2 stroke.
Also, I will mount it on a Super Clown for the real test.
Two early observations - electric starter is required and it's thirsty.
Bob Z.
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It is so smooth it's rediculous - feels like an electric motor.
It's a tad heavy but to be sure, I'll get some comparison weight figures as well as some photos.
Since it's a .30 CID, I'll compare it to a SAITO .30 and a .30 CID 2 stroke.
Also, I will mount it on a Super Clown for the real test.
Two early observations - electric starter is required and it's thirsty.
Bob Z.
Just like a "real" Wankel . . .
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How do you measure the swept vol. of a Wankel? Is it the swept vol. of 1 chamber during one rotation of the rotor? Or the swept vol. of all three?
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Just like a "real" Wankel . . .
Bob,
I've had both Wankels and they are a hoot. I used them in R/C, 2 of them went into a Zirolli Grumman F5F
My first one wore out a little prematurely as the instructions were quite specific about using a fuel with 25% oil in it. I used 20% and believe it or not I had to rebuild the rotor seals in very short order. That was a Mk1 with the cooling shroud.
It is true that the motor hums at full throttle and is a kick at idle. 4 OZ is not going to rock your world in flight time.
Dennis
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I had an OS Wankel in an r/c plane years ago. I think it was the early type but I'm not sure. It started and ran very nice. The only thing I am sure of is that it had the power of a .25 or .30 but used fuel like a .60.
Don
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Talk to John Miller, he had one in a Jack Sheeks Beechcraft Staggerwing.
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The Wankle ran smoothly, needed an electric starter to get it going, and had the power of a decent .40, even though it was considered a .30.
They only measure the swept area of one face of the rotor, but in reality, there are three faces firing during a single revolution of the rotor.
It was heavy, and used a lot of fuel. It powered the plane just fine though.
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Thank you John. This is what I thought. So in reality it's a 90! No wonder it's thirsty for a 30! But wait a minute, in a conventional engine, for one rev of the engine we get one rev of the output shaft. In a Wankel, we get (my brain hurts) revs of the output shaft for one rev. of the engine. But this is similar in effect to a transmission shaft behind a gearbox, the transmission shaft does ? revs for 1 rev of the engine, but we still measure the swept vol. as one rev of the engine. Therefore so we should with a Wankel. So a wankel 30 = a 90. Q.E.D. ???
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I seem to remember that there are 2 revolutions to the out put shaft for 1 revolution of the rotor. So it should be equivilant to a .45. H^^
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I had one of the early Wankels years ago in the nose of a Sterling Stearman. It was a blast to fly with the throttle it had. Wide open throttle was like flying an early rat racer. I could start mine by hand by drowning it with fuel in the intake. Like a dummy I sold it. By the way, no vibration if the prop was balanced. Been trying to get a good one for a decent price. The one I had only cost me $50.00 as the guy had no use for it. Having fun, DOC Holliday
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I ran one a while back and it tended to run HOT! Used way too much fuel also! It was the earlier version though....
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I seem to remember that there are 2 revolutions to the out put shaft for 1 revolution of the rotor. So it should be equivilant to a .45. H^^
But what about the gearbox factor? In a conventional engine-g/box set up we don't consider the engine capacity changes according to the gear ratio of the output shaft behind the g/box, so why take it into account in a Wankel, in which the output shaft is geared up relative to the rotor? I still reckon a 30 Wankel is really a 90. E.g. when we attach a reduction gear to a 60 to enable it to turn larger props, we still consider it to be a 60.