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Old 08-05-2020, 02:52 PM
  #47138  
Glowgeek
 
Join Date: Feb 2016
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Originally Posted by Hyjinx View Post
Ok Guys
Utter devastation and woe unto me.
My FA 62 wouldn't lift my goldberg arf cub off the water this morning.
7000 rpm with a 12/10 on it. Couldn't break the water lock.
Probably lucky it didn't on the maiden.
The problem is that the 9 " prop pitch is too high, it's dragging down an engine that makes peak torque at somewhere around 8200 rpm and peak hp at well over 11k.

With the Xoar 12x9 at 7000 rpm you are making only 2.88 lbs of thrust and .46 hp. Put a 12x7 on that same engine and you'll be making 5.31 lbs of thrust and .896 hp at 9300 rpm richened for flight.

Refer to bottom graph:




Hope this helps in some way.

Lonnie

Last edited by Glowgeek; 08-05-2020 at 02:55 PM.