[NSRCA-discussion] triangulation trimming

[Budd Engineering]

Vicente,

When you say your CG is 3/4" ahead of the wing tube, are you  
referencing from the center of the tube, or from the front edge of the  
wing tube?  There's quite a difference between the two reference  
points on the Abbra due to the size of the tube.

Thx, Jerry

Budd Engineering
jerry at buddengineering.com
http://www.buddengineering.com

On Mar 22, 2008, at 6:00 AM, vicenterc at comcast.net wrote:

> Chris,
>
> What is your new CG position?  I am close to 3/4" in front of the  
> wing tube.  In my first Abbra I was around 0.6 positive and elevator  
> position was at 0.  In my new newer Abbras, I procrastinated and  
> didn't install the wing adjusters.  The planes were ordered to 0.5  
> but they are really a little below 0.5.  I am installing wing  
> adjusters now to increase incidence to around 0.6 and see what  
> happen.  I expect that elevator position is going to get closer to  
> zero as I increase the incidence.  That should reduce the amount of  
> mixing in knife edge.
>
> I am not sure if you are going to be able to fix the elevator  
> mixing.  In my old Abbra I was around 6% up both ways.  The engine  
> was at 0.5 degree down so probably that helped.  You need to make  
> 100% sure that the engine is NOT any amount up.  That could be a  
> problem.  I prefer to put it small amount down to cover my error.
>
> I agree with you in regard tracking improvement moving the CG  
> forward.  I got the same experience.  Another point, the Abbra  
> rudder is very powerful.  When you check the mixing in knife just  
> use the amount that is required to keep level fly including power  
> setting.
>
> Snaps. Increasing the down elevator throw probably is going to  
> help.  I am around 10 degrees up and 12 degrees down to get balanced  
> feeling.
>
> Keep telling what is your experience in the next few flights.  I  
> still grounded this season but I expect to start flying next  
> weekend.  I will report on the new conditions after increasing the  
> incidence.
>
> Happy holiday season to all.
>
> --
> Vicente "Vince" Bortone
>
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