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

let us discuss how stupid I am!

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Old 01-13-2003, 04:42 PM
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firefighter
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I am not capable of grasping the whole diameter/pitc thing on props. Lets take my thundertiger pro 46 , towerhobbies muffler and coolpower 15% . With a 11/6 MA, I will get 11500-12000 rpms. Witha 10-6 apc, I will get 15000 rpms. I figure if I got a 11-6 apc, it would be more of an apples to apples comparison, but I am lazy. I put a 10-7 apc on......horrible rpms...maybe 12500. The only thing I can figure out is it is WAY easier for this engine to turn pitch, than diameter..someone help me out here, I rode the small school bus
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Old 01-13-2003, 04:48 PM
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ChuckAuger
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Generally speaking, a MA of the same size and pitch will turn up higher than an APC.
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Old 01-13-2003, 06:13 PM
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The APC's really bite the air and use all of the power, the APC 10x6 should be faster than the MA 11x6, not only because it turns faster.
the way prop numbers work is this... diameter gives you thrust, this is good for funflys, but because its big it cant have a high pitch which is good again for funflys because you dont want speed. fast planes want high pitch to go further on one turn, they cant swing the large blade so have to be small, they have a high top speed but not much thrust to help with take off.
the 6" pitch prop is a good sport size for most engines using diameter to suit the engines power band.
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Old 01-13-2003, 07:49 PM
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Default Yo, ChuckAuger....

I found out the same thing, but nobody believes me.
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Old 01-14-2003, 02:52 AM
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Default prop load

prop load = diameter*cubed * pitch

You are correct. Diameter is harder to turn than pitch.
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Old 01-15-2003, 02:49 AM
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You have not said what kind of plane and more important, how you want your plane to perform.
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Old 01-15-2003, 03:07 AM
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Flyboy Dave
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Default Yo, Cyclic....

....my findings are that pitch is harder to turn than
diameter..... :stupid:
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Old 01-15-2003, 02:14 PM
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Originally posted by Flyboy Dave
....my findings are that pitch is harder to turn than
diameter..... :stupid:
Heh heh....maybe that's why yer so dang slow!

Down the size, and up the pitch FlyBoy.....I git tired of seeing you in the "rearview"!

Gary
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Old 01-15-2003, 03:03 PM
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Flyboy Dave
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Default Yo, Cyclic....

....just when ya' think it's safe to go back up....

Here comes "Jett Face" Gary with another "load".
( I gotta get back to work on the secret weapon )
Gotta smoke that guy somehow...heh heh heh.

Awhile back I put 11-10 Zinger on a .60 FSR, just
to see what it would do. (yeah right) It went from
14K to about 10K..he he....ran like an old Enya with
a potato stuck up the exhaust.... :stupid: One lap,
11-7 1/2 MAS back on.
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Old 01-15-2003, 06:41 PM
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Default let us discuss how stupid I am!

This is not a jab at all but in my "vast" 5 years in this stuff I have not found a reason to care about it at all! Formulas a great on paper and static but can drive you nuts trying to apply it. Not worth the aggravation. If the stupid plane does not do what i want change the prop.
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Old 01-21-2003, 01:45 AM
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Default Overloaded

Thats what a 10/11 does to a engine that normally turns a 10/7.5
Try a 8/11 or a 7/11 instead... if ya can find one. Thats a lot of pitch.

Dia converts into AREA swept by the blade, pitch is no-slip climb into that area
Area goes up fast with longer props.
Thus, if you up the pitch an inch, ya gotta drop the Dia more than an inch, I see some racers shaving dia off props and test flying on radar, they find what works for the plane /engine combo and use it.
according to my fast math and , you actually need around a 8.75 / 11 to equal the load of your 10/7.5 So get a 9/11 and lop 1/8" off each tip, then balance.

Try it !!!

Ramjet
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