[LASS Soaring] "New No Stretch Winch Line IS Different..and That Means More Attention to ..."

[GordySoar at aol.com]

Hi Guys,
 
The new winch line doesn't stretch and is heavier than the line of the  past, 
and a more than a few pilots have found its producing a few more pop  offs 
than we used to see.
 
The heavier load on the plane means more stress on the elevator's rear  end.
 
So if you have experienced an unexplained pop off, check your pushrod and  
linkage etc for flex.
 
Turn on the system, so that the servo is holding, then gently press down on  
the back of the stab, it shouldn't tip down with almost any amount of force. 
If  it does, then while under load during launch, any down action is like 
letting a  rubber band snap, instead of getting a little down you end up with a 
jerk amount  of down..and a recovering up movement which pops off the plane.

AVA's and Supra use the 'tipper' stab system and they are especially  
susceptible to this action, so make sure that there is no flex anywhere in the  
linkage.  Use the shortest possible arm on the servo to reduce the leverage  
applied to it.
 
Wood RES planes that launched just fine in the recent past are suddenly not  
launching so well....because of stab flex and infirm linkage systems.
 
Those of you using foam in the tail booms to support the pushrods are prime  
candidates for pushrod flex...so do the stab test to confirm you got it  right.
 
I see guys playing with tow hooks and CG trying to get a ship to launch  high 
or reliably, but when I check their stabs, I can get a 1/2" of  deflection.  
Sort of like using spring steel as a pry bar.
 
Should be common sense to check this stuff but common sense is uncommon on  
the flying field and building board. :)
Gordy
 
Don't bother to argue the point, just do the test. ;-)
Gordy
 



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