Cc: "Mike Sylvester" <>
Subject: KR> Flew yesterday.
I've been working on an internal trim system and I think I finished it 
yesterday. The weather warmed up enough for me to test fly it and I was happy 
with the results. My original thinking was that I didn't want the drag of two 
surfaces working against each other like the trim tab does. I was looking for 
every MPH I could get. If I could go back in time, I would just do the Ray 
Allen trim tab system and be done with it. To all you builders out there, Keep 
working and stay with what you know works, All the guys that went before us 
have done all the testing.

Mike Sylvester
kr2s builder


When I cut the tail off my KR and built a larger tail, I decided to use a 
spring biasing trim system, also in an attempt to keep the tail as 
aerodynamically clean as possible.  I flew with it like that several hundred 
hours from 2005 - 2013, but would consider it to be a miserable failure.  As 
the plane speeds up, the elevator control pressures load up and pull on the 
springs.  It would never reach an equilibrium, regardless of the speed, so the 
plane was constantly pitching up and down and wouldn't ever hold an altitude.  
I could have improved it, but I don't believe I could have ever cured it with 
that configuration.  I finally removed the spring biasing system and put a trim 
tab on the elevator with a Ray Allen trim servo.  Details of both installations 
are on <>

On the SuperCub Clone I had a single bowden cable control to the trim tab as 
per Wag Aero plans.  That cable started flexing and failed in flight creating a 
high speed and violent flutter that shearedmost of the rivets attaching the 
trim tab and caused some cracks in the elevator that had to be repaired.  (Also 
scared the crap out of me!)  The Cub was also modified so it now has a Ray 
Allen trim servo.

-Jeff Scott
Cherokee Village, AR

Search the KRnet Archives at
Please see LIST RULES and KRnet info at
see to change 
To UNsubscribe from KRnet, send a message to

Reply via email to