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Scorpion Power Scorpion Power
HelicopterGasser Model RC HelicoptersOther › Headspeed and gear ratio's
09-14-2007 05:34 PM  10 years agoPost 61
AceBird

rrElite Veteran

Utica, NY USA

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Gearing is up in the air as well.
Gearing is not up in the air, gearing is everything. With a simple spring scale and a rope you can find exactly what max power your engine has. Simply change the max pitch setting and run a few pull test to see what gives the greatest pull. Change the gearing and do the same thing. If you went the wrong way on the gearing it will be obvious. So you turn around and go the other way. Continue changing the gears until you get to the point where the max pull starts decreasing.

Now this will tell you where the max is but running at the max is not a good idea. If you run at the max the instant you require a bid more power you will dog and you won’t be able to maintain constant headspeed. So then you just go to one tooth higher (giving more torque) on your gear ratio.

Ace
What could be more fun?

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09-15-2007 02:35 AM  10 years agoPost 62
lperagallo

rrApprentice

Westfield, Indiana,​USA

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Simply change the max pitch setting and run a few pull test to see what gives the greatest pull.
Ace,

Could you give the details on a safe way to do a "pull test". What range should the spring scale be capable of?

Twin Bergen 44Magnums FBL Wren NW44s - Kero start

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09-15-2007 12:44 PM  10 years agoPost 63
AceBird

rrElite Veteran

Utica, NY USA

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Could you give the details on a safe way to do a "pull test". What range should the spring scale be capable of?
Anchor a 30 lb fish scale with a cement building block and attach a 100’ rope to the other end. Then tie the other end of the rope to the heli such that it pulls through the center of gravity. Carefully bring the rope up taught and then gradually add collective until the engine starts to bog. Note the stick position so you can measure the pitch. You will also need an accurate headspeed that resulted from the test.

You can also produce the same results negatively with a compression scale and running the collective through negative pitch on the ground but you might be a little off because of ground effect. If you perform the test with and without the tail feathers you will know what they consume in horsepower. Also a camera might be required to read the scale if it doesn’t have a tell tale device.

Ace
What could be more fun?

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 4 pages [ <<    <     2      3     ( 4 )    >    >> ] 3779 views
Scorpion Power Scorpion Power
HelicopterGasser Model RC HelicoptersOther › Headspeed and gear ratio's
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