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kolb washout / trim

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by0ung(at)brigham.net
Guest

Posted: Sat Jan 14, 2006 11:10 am Post subject: kolb washout / trim

The Kolb MkIIIc/912ULS I have has a strong tendency to turn left.  The

bungee cord

does a fair job of countering that, but I'd like to effect a bit more

nominal

solution.



So, I have TWO questions:



1)  I'm thinking about adding an aileron trim.  Can anyone suggest

approaches to

doing that, suggest methods/materials, and maybe even details on how to do

it.



2)  I've been told by at least two people, "oh, check your washout!" as if

to say

that might solve my strong-left-turning-tendency.  And although I have a

very

general idea what washout is, I would have no idea about how to MEASURE it

and then, if were "wrong", how to correct it.



Any constructive comments?



  -- Robert



--------

Robert



1 st   aileron trim   

If the plane wants to roll to the left,  it would be best to add a trim tab

to the bottom trailing edge of the right aileron   I built mine one rib bay

wide, and it was made of .032 alum.   The measurements was, as close as I

can remember,  wide enough to rivet to the ribs  on each end..  and about 3

 inch from front to back   there was a bend at about the 1  inch mark.

The bend was enough so that when the 1  inch side was held flat on the

workbench the end of the 2 inch side was about  inch off the table top.

The 1  inch side was riveted to the bottom of the trailing edge tube and

the bottom of the ribs. With the bend pointing down.   After trial fitting

the trim tab. I put a piece of masking tape across the front edge where the

tab touches the fabric,  then I ran my fingernail over the edge and cut the

tape ( do not use a knife )  when I did the final install I put a small

bead of silicone rubber on the tab where it contacted the fabric and the

excess squeezed out where the tape was cut.    I then wiped the excess off

and removed the tape for a no smear installation..  I think I had 1 rivet on

the leading edge of the tab in the ribs and 3 or 4 across the trailing edge.

After trials you may need to bend the tab more or less.



2 nd.   Washout.

Washout is a twist in the wing so that the leading edge and trailing edge

are not straight in line with each other.    to measure you hold a level

from the leading edge to the trailing edge of the right wing at the inboard

part of the wing.   Prop up the tail until the level  is level.   Then

repeat on the outboard end of the wing   if the level  is still  level

there is no washout, or washin.   Kolb wings should be built straight with

no twist..  if there must be an error it is better to have the wing twisted

so the leading edge of the outboard part of the wing is lower than the

trailing edge.   Some aircraft have a 2 or 3 inch twist in the wings

this causes the wing tip to be at a lower angle  of attack and will stall

last,  giving aileron authority through a stall    now that we have done

the right wing, leave the tail where it is and check the left wing   the

inboard part of the left wing should be level,  if not the wing attach

fitting may have been drilled incorrectly.   Then check the outboard end of

the wing.  It as well should be level   again if there is an error it would

be better if the leading edge was lower than the trailing edge.



The worst case is if the center of the wings were both level and one wing

had the leading edge wing  tip high and the other wing leading edge wing tip

low   



If you have any further questions feel free to contact me



Boyd Young

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Richard Pike

Joined: 09 Jan 2006
Posts: 1669
Location: Blountville, Tennessee

Posted: Sat Jan 14, 2006 11:54 am Post subject: kolb washout / trim

If you make your trim tab adjustable, then you can set it to level when 

you have a passenger, and down when you are solo, and have no stick 

pressure either way. Here's how I did it, crude, but works good.

http://www.bcchapel.org/pages/0003/pg6.htm



Richard Pike

MKIII N420P (420ldPoops)



boyd wrote:



 	  Quote: 	
		  



The Kolb MkIIIc/912ULS I have has a strong tendency to turn left.  The

bungee cord

does a fair job of countering that, but I'd like to effect a bit more

nominal

solution.



So, I have TWO questions:



1)  I'm thinking about adding an aileron trim.  Can anyone suggest

approaches to

doing that, suggest methods/materials, and maybe even details on how to do

it.

- The Matronics Kolb-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Kolb-List

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

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