Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

O.S. .40 VR-P any good?

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Old 04-10-2008, 10:10 PM
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Default O.S. .40 VR-P any good?

Hey everyone. A guy at my field brought one of these down and ran it up on a test stand and it spun up to 27k (not sure of prop size) and sounded mean. I see some for sale here, so are they any good? I have been flying a clipped wing Lanier Predator with a Jett .46 and although fast, I want to go faster! Got a midget mustang that had a Nelson on it (clocked it at about 180). So, is this engine anything near a brand-new Nelson LS 40? If not, I won't bother and I will just go for a new Nelson. Any thoughts are appreciated! -Chris
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Old 04-10-2008, 10:26 PM
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Default RE: O.S. .40 VR-P any good?

They were a pretty good design at the time they came out. Nelson borrowed some of the OS measurements when he came out with his first Formula One pylon motor, while other parts of his design were lifted from Super Tigre X-40. OS worked on their pylon engine for quite a number of years, and as a box stock engine it was better than the stock X-40. The biggest problem for the OS was that everyone was running X-40's at the time in highly modified form, and there wasn't a network of people giving the OS the same attention.

Things for the X-40 drivers improved a lot when Nelson started making piston/sleeve/heads for the engines. Much more consistant parts, better taper on the sleeves, and a generally better fit. But when he came out with the entire engine, much better breathing and a heavier sleeve.

27K is a good run up rpm, but not a flying prop. You need to keep it loaded to the 22-23K range.
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Old 04-10-2008, 10:32 PM
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Default RE: O.S. .40 VR-P any good?

So are you saying that a new Nelson 40LS will blow one of these out of the water?
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Old 04-11-2008, 01:11 AM
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Default RE: O.S. .40 VR-P any good?

All can be very close on power. Depends on how the OS is set up, what kind of plane and prop.

Old F1 engines are more demanding, if it is truly set up for F1 they ran on 60-65% nitro and used a plug per flight. Plus the noise if run open exhaust is around 115 db. But on the other hand, one should easily push a Q40 sized model to the 200+ mph range, since they have been shown to do that with a bigger F1 model.

I've got half a dozen X-40's and four Nelson RIRE F1 engines left over from the F1 days that I want to run again one of these days to see what they can do in a purpose built speed ship. Their big advantage over the newer racing engines is that without a tuned muffer, there is no limit to the upper end of their rpm in the air. So while they turned 27K in the air dragging a F1 airframe in level flight, they should turn above 30K out of a slight dive. With a carbon Q40 prop like the APC 7.4 X 8.25 prop the numbers look promising.
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Old 04-11-2008, 11:34 AM
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Default RE: O.S. .40 VR-P any good?

HP...did you run that 7.4X8.25 carbon prop on an X-40 (or two ) then?
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Old 04-11-2008, 12:08 PM
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Default RE: O.S. .40 VR-P any good?

Not yet.
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