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

which props are recommended

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Old 12-09-2006, 08:08 AM
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rickburnout666
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Default which props are recommended

Hello everybody , there are many of you on the aero sites so someone should be able to give me some ideas, i hope .
I have two engines the 1st one a magnum .21 and the 2nd is an os .25 , i wish to run them with Graupner triple blades but i dont know which sizes can be used, and i dont want to damage them either, i also have a .15 coming from a friend not sure what make it is or what triples that can take ? i hope someone out there can help.
Thanx in advance, Rick
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Old 12-09-2006, 08:28 AM
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Default RE: which props are recommended

I have little experience with engines under .46. I do have a plane with 3 blade and they recommended a size smaller than recommended for 2 blade. I have a 4 stroke OS 91 and have a 3 blade 12X6 prop on it which was recommeded for that engine., Check the paper work that came with the engine and then use that as a rule of thumb as to what 3 blade would work.

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Old 12-09-2006, 09:33 AM
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Default RE: which props are recommended

You will lose some engine performance with a 3 blade over a two.
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Old 12-09-2006, 09:55 AM
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Default RE: which props are recommended

thanx for the tips , i dont want to get supersonic speeds out of the engines, as they will be fitted to ...? not sure wat you call it but the designed aeroplane/flying machine?? will be fixed to a a wire and spinning in circles, but i want them with 3 blade props , i am unsure what 2 blade props they use too? like i said, i dont want to damage them by putting the wrong size props on.
I should have put in the subject , I AINT GOT A CLUE lol
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Old 12-09-2006, 12:32 PM
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Default RE: which props are recommended

Hi!
7x6 or 8x4 or perhaps a 8x6 3-blade...but remember that 3-blade props are worse than 2 blade props.
Go with a 2 blade 7x5 or 7x6 APC if you want speed.
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Old 12-09-2006, 12:42 PM
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Default RE: which props are recommended

Thanx jaka, but on which engine would they be for ? .15 .21 or the .25 ?? i think i am what they call a newb to this sort of thing ??
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Old 12-09-2006, 03:42 PM
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Default RE: which props are recommended

Control line planes in the .15 to .35 size range need a decent amount of speed to be maintained to keep good line tension and control authority. There is no point in getting started in C/L with an engine prop combo that compromises the planes' ability to maintain line tension. If you want to start out slow, use the .15 with either a 8x3 or 8x4 Master Airscrew prop on a plane with a fat airfoil. Save the 3 blade props for later when you become an accomplished Ginsu Masta of the stunt pattern and your plane and skill level is finely tuned enough to nurse a slow moving .40-.60 sized ship through the stunt pattern. If you insist on a 3 blader for the .15, try to find a 7x3. Most .21s that I know of are high revvin' engines that need a easy prop to turn, most will have a very narrow range of props that they will be happy with. you might find that a 7x3 or 7x4 three blader is all a .21 will turn with any sort of willingness. The AMA might still have a chart that shows recommended engine / prop / applications, though last time I saw that chart, it seemed like it needed some updating.
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Old 12-09-2006, 04:27 PM
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Default RE: which props are recommended

Ok thanx for the tips , I should have said at the begining There are 3 rules to this project.
1: Engines must be under.30 .
2: 3 bladed props must be used .
3: The aircraft can not resemble what we know as an aeroplane.
1: i have engines already
2: i can have and do need help with
3: I can not have any help with

perhaps speed will help, therefore i need 3blade prop sizes for the 3 engines i now have,
Every bit of help (prop sizes) will be greatly appretiated
Thanx Rick
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