RCU Forums - pipe question

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- - pipe question (https://www.rcuniverse.com/forum/extreme-speed-prop-planes-104/9049242-pipe-question.html)

I have a Rossi R65 and gonna use a 11x8 prop on it... got a GP Revolver plane... I need to get into the 16K RPM range... I am gonna fly it fast only and look good while doing so... I have seen the plane do 159mph with an electric and 129 with a 55AX... is there an OS muffler which I can use with the Rossi to give me those RPM's? I only have the engine...

RE: pipe question

A Jett FIRE .65 will only spin an 11-6 at 15k or so, that is their listed performance and I believe they have to test to that before being released. They're both strong engines, I dunno which one has the edge, but simply increasing the 11-6 to 16k from 15k requires about 14% more power. Now add 2" of pitch, and I'd be very surprised if that .65 is capable of doing what you are asking. Is it known to be able to do so?

MJD

RE: pipe question

actually a 11x7... Rossi R65 puts out 3.5HP @ 16000... but I want the RPMS for speed... with 11x8 I am hoping for 14K RPM or so and in air while diving it will pick up...

RE: pipe question

here is a chart... could you tell me if I am realistic or not? will I lose speed beyond these RPM?

http://i531.photobucket.com/albums/d..._639/rossi.jpg

RE: pipe question

3.5 Hp @17K rpm in a .65 is real optimistic. A Jett 90LX on tuned pipe, one of the most powerful performance sport engines ever made would have problems spinning an 11X8 @ 16000.
The chart shows the Rossi's best static power with a 11X8 is at 13300. If the prop is an APC that's 1.7 hp, actually not bad at that low of rpm. I would expect it to unload in flight at best another 1000 rpm.

They claim the highest power at 17000, so find an APC prop that loads it there with the best tuning on the pipe, once you do that it's easy to figure the HP.
I'm thinking you would be lucky if you could swing an 11X6 there.

That Rossi pipe they used in that test probably won’t be any better than any other brand of correctly sized chamber; it's all about tuned length.
No, OS won’t have any tuned muffler that would come close to what you want.

Insistently the pitch speed with an 11X8 at 14K is 106 MPH and at 16K its 121MPH, not that I think it will stay there in level flight after a dive with that prop.