Hi Sabrina,
I'm really not sure. I hooked up the elevator and rudder cables and
safety wired them before getting the tensiometer. I intend to take
them all apart and redo the tension to the new specs some day.
As I recall the process, the tension really didn't build until the
last turn or so on the turnbuckle. This would be the case if there
was very little stretch in the whole system. My best guess now is
backing off a half turn on the turnbuckle would remove all the
tension in the cable.
My point in making my post was not clear so let me try to make it
clearer. It is a lot easier to figure mechanical advantage and work
from force (applied to the turnbuckle) to force (tension on the
cable) than to go about analyzing the impact of the thread on the
cable. Indeed, I am not at all sure the cable is the most
interesting part of this whole system. It may be that the aluminum
sheets, plastic fairleads, and other exotic things like play in the
control surface hinges play bigger roles than stretching the
cable. This is just as true after some time has passed as it is when
first applying tension to the cables.
After half a lifetime working as an electrical engineer, I am a firm
believer in "Closed Loop Control Systems". In this case, it means
taking measurements of cable tension and adjusting the turnbuckle to
get the tension you want rather than trying to predict the tension
achieved from a certain amount of turns. The second choice is an
"Open loop" system since there is no feedback of results.
Sorry about the lecture . . .
Paul
XL getting close
At 10:39 AM 11/30/2008, you wrote:
>
>Dear Paul,
>
>So, when you back off the tension 1/2 turn what happens?
>
>A full turn?
>
>The other way?
>
>How many degrees of rotation per 5 pounds of tension change each way?
>
>If you use those turnbuckle safety clips rather than safety wire,
>how much rotation can you get with those installed? (We are talking
>about the Zenith supplied turnbuckles)
>
>Thanks,
>
>Sabrina
