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O.S. 49-PI Wankel

Old 04-15-2004, 06:10 PM
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IA-Flyer
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Default O.S. 49-PI Wankel

SIG 10%, 20% oil
1050 above sea level
72 degrees

30 minutes run time on new engine, break-in just completed. These readings were taken at a flyable rich setting and will probably improve as the engine gets more run time.

APC 11x4 11800

MA 9.5x6 13,900
Old 04-15-2004, 06:15 PM
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Default RE: O.S. 49-PI Wankel

You gotta love them. Don't know which kind of oil you are running..........but if you switch to castor.....it will run even better......



Neo
Old 04-15-2004, 06:36 PM
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Default RE: O.S. 49-PI Wankel

Hi Neo,
It's 50/50 castor / synthetic
I broke it in using 25+% castor fuel. Wow what a mess

O.S. just says 25% castor, Bax in OS support says 18-20% regular fuel with castor content.
What do you think should I up the castor content or should the 2-stroke SIG fuel I use in everything else be ok?

Thanks!
Old 04-15-2004, 08:42 PM
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Default RE: O.S. 49-PI Wankel

Personally, I ran 15% Nitro Cool Power. I chose the synthetic becasue it doesn't stain like castor does. The wankel runs so hot and so messy, it's self explanatory why I ran synthetic. The idle wasn't as good as the castor.......but still acceptable. Here's why I think O.S. wants you to run a higher oil content. The tolerances in the engine are to say the least.......not very tight. The extra oil helps to "seal" thing up a bit so it will run better. I don't think it has anything to do with lubrication. That's why the engine will run better off castor then synthetic. I know.........my thoughts aern't well put together and they don't flow..........but I'm extremely tired here. Sorry about that.


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Old 04-15-2004, 10:02 PM
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Default RE: O.S. 49-PI Wankel

Made perfect since to me, and I think you’re right. The high caster content is probably used as a substitute for side apex seals.
With the amount of fluid coming out of the vent I cant imagine this engine ever being starved for lube and everything that turns is on a ball or needle bearing. I just want to play it very safe!

Thanks for the input, it’s good to hear someone is running a wankel on pure synthetic.

Jim
Old 10-12-2005, 06:43 AM
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Default RE: O.S. 49-PI Wankel

Mix: 20% castor, 5% molsyn 150 3% nitro

9x6 APC 16300

9x5 APC 17100 (recommended prop for normal plane)

This Engine should never get less than 25% oil, most of it should be castor.
Old 05-08-2006, 05:11 PM
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Default RE: O.S. 49-PI Wankel

Castor will eventually gunk up the engine. Castor is obsolete as an oil choice.

Broke mine in on Fox fuel juiced to 25% castor. Ran 14,000 w/ 9x6. Nasty mess. Switched to Powermaster YS 20/20 20% synthetic 20% nitro. Upped prop size to 10X6 and pulls 14,000 rpm.

So if you want more power switch to synthetic and up the nitro content.

14,000 is the peak torque rpm for this engine.
Old 05-09-2006, 04:04 AM
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Default RE: O.S. 49-PI Wankel

For some peaople castor is obsolete and for others it is the insurance for a long life span of the engine.

I have seen a few O.S. Wankel engines with poor performance after a short time of use with synthetic only fuels. The seals were worn out.
The Wankel runs much hotter than a normal 4-stroke model engine. Castor gives extra safety at high temperatures.
This is why I use castor.

The power output of the wankel is much better if you use nitro. The torque curve is relatively flat and if the engine is not overheating it allows a wide range of different props.

If the rpm is >19000 the risk of chatter marks in the case and wearing of the seals is very high.

I inject some synthetic oil through the carburetor after flying. This helps against the castor gunk problem.
Old 05-12-2006, 04:14 PM
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Default RE: O.S. 49-PI Wankel

Hi there,

NeoGenesis, you say the tolerances in this engine are not very tight. In my oppinion, you couldn't be further from the truth. As you probably know, it doesn't use any side seals. In order to get the compression that these engines have, you are looking at a rotor to side housing clearance of around 4 to 5 microns (0.004-0.005mm). This means you need a near-to-perfect parallel rotor and housing along with very accurate dimensions. These engines are exceptionally well built and building a good, running piston engine is easy in comparison.

I do agree that the castor probably helps with gas sealing, but at the same time, I also think that these engines do need a good quantity of oil for lubrication purposes.

Doesn't the sound of these engines also take some beating? It takes lots of 4 stroke cylinders to beat that peripheral port idle.

Regards
Warren
Old 05-12-2006, 07:38 PM
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Default RE: O.S. 49-PI Wankel

I wasn't referring to the tip seals themselves, however if you've ever torn one down....there isn't much pressure there. I meant more of the front and rear case mating up to the the ring "center section" of the engine. Mine would seap and drip fuel all the time. However the damn thig ran like a top and made a hell of a lot of power.



Neo
Old 08-19-2009, 11:19 PM
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Default RE: O.S. 49-PI Wankel

The centrifugal force of the rotor spinning, applies more pressure to the apex seals than just what the springs are applying to them. I would rather follow OS's instructions and use fuel with 25% oil. Right now i'm running fuel with an oil content of approx 30% (40% of that castor, 60% synthetic) because i added too much by mistake. Runs great on it though. I'm not saying that maybe there aren't synthetics out there that might be as good as castor when the temps get high but castor has proven itself and i'd rather just stick with using it in these crazy little engines.

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