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Prop extension and pitch control force

Mikeyb

Well Known Member
Silly unquantifiable question but…Im lucky enough to have a fellow RV8 builder at my airport that is the same phase of flight testing I am. We are both new to RV’s and spend hours talking about what we feel.

Mine is a built to print bare bones sport plane with a Hartzell CS. His is a show plane with all the IFR stuff and a custom cowl including a. 4” prop extension and a 2 blade Cato prop.
The CG of the two are very close. Mine is a little lighter. He perceives the stick force in pitch to be higher than I do.

Would moving the prop forward increase the pitch force given the same measured CG?
 
Yes, putting something heavy even farther away from the CG increases the moment of inertia (the resistance to rotational acceleration).

Think about how easy it is to spin a baseball and how much more difficult it would be to generate the same spin if you attached two half baseballs at opposite ends of a stick.
 
Pitch Force

The one with the perceived higher pitch force has a Catto two blade which is much lighter. Should have lighter pitch force despite the extension.
 
I forgot about the angular momentum.

This is a silly post as it’s all conjecture but in a way what he felt was more resistance to change than actual stick force
Mike
 
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I believe the radius of the trailing edges of the elevators also contribute to stick force.. maybe someone with more experience can chime in here.. I thought if the training edge was underbent, the stick force could be lighter than normal..
 
Way too many variables. The OP already listed a couple. You'll get a list of potential contributors here but nothing quantifiable. Have fun with it.
 
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