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

Powerplant for future build thread..

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Old 05-20-2014, 03:50 PM
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MJD
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Default Powerplant for future build thread..

Next in my list of glow conversions of cool lekkie pylon racers will be the .15 machine.

The pipe is on the way or I would have included the picture.

Profi "hybrid" engine - 2014 TOP F2A top end, with Junior bottom end - the difference being regular ball bearings on this versus direct inner race on the crank. The net effect would be somewhere slightly south of the rather $lofty TOP F2A engine, and north of the Junior F2A engine in performance. I have a head button for 10% nitro fuel which I will definitely use. Prop is an Eliminator 3x6 (or 1/2 of a 6x6) with integral brass counterweight designed for these engines.

Airframe? One of a short list of models between 160 and 210 sq inch.

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Old 05-20-2014, 04:04 PM
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FAI engine designers must never sleep..?
Getting rid of the inner race frees up a lot of area relative to the size of these little engines.

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Old 05-20-2014, 05:09 PM
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Oddly I asked Alberto about that, and he said the crank passage is the same. Got to do with drag I guess.
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Old 05-20-2014, 05:44 PM
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Then being able to use larger balls has something to do with bearing drag...?
I'm surprised it has nothing to do with the internal passageway. That's what sets the Nelson .40 apart from other .40s is the massive passage.
It could be that Profi .15 is already at a practical limit for air handling ability.
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Old 05-20-2014, 07:19 PM
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Well, I still wonder about that. I'd have to drop $850 to find out.. nah!
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Old 05-25-2014, 04:24 PM
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The plane you will need is something like a Beretta 21. i have one of these I plan use for my Profi 15-21 size engine I have.
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Old 05-25-2014, 07:09 PM
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Running the balls directly on the shaft makes them rotate slower, thus less drag.
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Old 05-25-2014, 07:11 PM
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That's from Look Bodt right?

Ariane
Sunracer 4
Or a little more wing area Avionik D06

Are the three I am considering for conversion to slime power. The Ariane has been flown on a Novarossi .21, but open engine/pipe.
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Old 05-26-2014, 06:30 AM
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Originally Posted by HighPlains View Post
Running the balls directly on the shaft makes them rotate slower, thus less drag.
Also there is the mass of the inside ring.
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Old 05-26-2014, 07:10 AM
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Originally Posted by HighPlains View Post
Running the balls directly on the shaft makes them rotate slower, thus less drag.
As a result it will be interesting to see where the engine ends up in terms of performance. It has one of the two main differences between it and the Junior model. Guess it depends which change is more significant.
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Old 05-26-2014, 03:21 PM
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Mind you there is no guarantee I'll be able to demonstrate anything of consequence in my personal handling of the engine.. . The rattiest engines I deal with are propped DF engines and little open exhaust engines. But I think it will be fine, I had a long chat with a couple of pretty savvy folks about it and I have a plan. And I will have in-flight mixture control and ukie fliers don't ha ha.. but they have somewhat fixed means of enrichening. And since I am not battling with Luis Parramon and the like for the FAI podium, I can avoid roasting engines in the quest for the last three kph..

I'm more worried about flying the aircraft then I am about handling the engine - but I think a small F5B ship has more visual .. what word am I looking for here.. presence(?) than a Demon delta. And I found the Demon at near 200 manageable - actually the speed was less the problem, it was more the vile handling until I got the balance and throws adjusted. It was a bit tail heavy first two flights, but I thought it measured out fine.. oops.
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