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"Extreme" speed doesn't actually apply to me but. . .

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

"Extreme" speed doesn't actually apply to me but. . .

Old 10-09-2010, 02:22 PM
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LongRifles Inc.
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Default "Extreme" speed doesn't actually apply to me but. . .

. . .Ihave a 50 size Voodoo mustang that I stuck a 91os fx into.

I have a 10x10apc on it and flew with it today. It's quite windy (20-30+) today in S.Dakota so it's hard to tell what the bugger is doing. Ran pretty good on the down leg side!

Anyways, anyone have a good speed racer prop set up on this motor/plane combo? I'm running home brew 15% nitro/20% oil right now and it'll twist this prop at 13,800 on the ground. Only engine changes are removing the cone from the muffler and I'm using a Tettra bladder tank.

I'm thinking 11x10, 11x11, or 11x12 even. (apc)

Thanks!

C
Old 10-10-2010, 07:34 PM
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freakingfast
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Default RE: RE:

11X12, 12X8, 12X9 APC or 12X8 S-2 MAS seem to work well on a tuned muffler or tuned pipe and should work with the stock muffler with or w/o baffle. I've tried those on my Phoenix Strega converted to Stiletto and the props are all close to the same performance on it with the same header length. If I had more time to fiddle with the header, one of those may shine well above the rest. I saw about a 2000 rpm jump over the stock muffler with a tuned pipe with those props. The 10X10 may not be enough prop for that engine and you may do better to move more air at a lower speed around the fuselage (more diameter & less pitch). I did tach a 10X10 on my 91FX and it did 14,950 on pipe (the pipe was tuned for 13,650 power peak) but I didn't try that prop on the plane.
Old 10-24-2010, 08:18 AM
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jaka
 
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Default RE: RE:

Hi!
What engine size??
For a .46-.50 two stroke I would choose a 9x7, 9x8 APC.
For a .61 two stroke I would try 10x7,10x8,10x9 APC.
Aah! .90 twostroke...then I would try a 10x9,10x10,11x6,11x7 or 11x8 APC.
Old 11-06-2010, 01:10 PM
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LongRifles Inc.
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Default RE:

I flew the other day with a 12x10 APC.  Seemed to work well.  I'm at 3500ft elevation so this may be why I'm getting away with the added pitch.

I've ordered a MAC header/pipe set up and a couple 12x12 APC props.  Maybe that will wake this thing up!

I'll post results.  A buddy is a cop and enjoys making "creative use" of his radar gun.

More to follow. . .

C
Old 11-06-2010, 03:05 PM
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jaka
 
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Default RE: RE:

Hi!
What rpm??? I think 12x12 is way too big!
You must up to 15000-18000 rpm to get any speed!
Old 11-11-2010, 10:35 AM
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Default RE:

The 12x10 APC screams!  I flew the snot out of it on Sunday and all was good.

Yesterday my MAC pipe arrived along with a pair of 12x12 APC props.  I'm optimistic.  I think this'll wake things up a bit.  If I'm down on RPM my intentions are to first shim the head and spike the fuel with a bit more nitro. (I have gallons of the stuff along with a hydrometer for "cooking" my own fuel)  If that "kinda" works I'm going to raise the exhaust port a smidge.  This will raise the usable RPM range of the engine.  It'll surely kill some of the "grunt" down low but I don't care.  This is a speed plane.  Just has to idle reasonably well and transition to WOT for take off.

I'll get some radar gun #'s once she's all done. 



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