National Aeronca Association Bulletin Board

The manual says the tail brace wires need to be tensioned to 350 to 450 lbs.
How do you do this?

Those of us on the fAA mail list have three music files that we have circulated that illustrate the "twang" on our musical tail brace wires.
That's the easiest way to do it. Tighten as if it were a bass guitar string to the right note range, somewhere between mine and Richards.

http://mail.westmont.edu/pipermail/aero ... chment.bin

Or this one:

http://mail.westmont.edu/pipermail/aero ... t-0001.wav

Mark,
Guess I missed them on FAA, but also your links both produce only error results! I'm trying to view them on my iPad so maybe it's an operating system problem. Most everything other than "flash" content is usually accessible. Any idea why ?

Dale

Thanks for the reply. I thought sound might be the answer.

Why not try a torque wrench on the wrenching flat.
Paul

I believe you need to use a flying wire tensiometer. Something like this: http://www.hangartoolbox.com/Tools/23.aspx. There are probably other ways to do it - maybe use a spring scales to measure the force required to give a certain amount of deflection. Relying on a recorded tone seems really "iffy" to me.
Raleigh

I'm not sure the tension is all that important. They should be snug enough to brace the tail or wing. If they are too tight it's just like loading up the plane with G's.
Paul

I should have said that differently. Using a recorded tone to gauge brace wire tension may be a little iffy in practice -- although the principle is sound.

I suppose it depends on the degree of tone deafness!

It works pretty well and it's what old time mechanics used to do anyway. I just tested the links
for the sound files and they worked fine with a PC... if you can't hear them, you may be missing a
codec or something to run them in your web browser.

BTW, just to make sure everyone understands, you can't use a cable tension meter on flying wires.
They need a specialized tool. And Paul is right, you don't want to put more stress on the airframe.
You need enough to keep everything in place and solid. Nothing more. I had heard of a
certain amount of pull and deflection, but the make it sound like a bass guitar string note
works better and I think has less possibility for damage.

David,

If you have the length of the flying wires and have a spring scale, I should be able to calculate the spring tension that will correlate with the flying wire tension.

Carl Prather