Question - for the 2-line button bellcrank how big of a loop to you use in the control wire to connect and how do you terminate/wrap/crimp the end? I looked at the AMA site and it seems to show two methods one with a single loop and a wrap that is soldered and second with two loops then wrap then soldered. What style is used for contest flying?

Since these are solid lines the solder of the wrap is OK? If two loops are used do you solder the loops also?

Best,   DennisT

A few more details:

If you do not have rotating spools on your bellcrank line terminations, then you must have the double loops in the lines per the rules. I completely agree with Giffy on the loop radius:  match it to the shank of your "button" so that the end of the loop is not constantly flexing with application and removal of line tension. And, make the loops long enough that you don't get permanent deformation of the loops when you install or remove the lines. Finally, before you fly, make absolutely sure that the teardrop shape of the loop returns after installation on the button. If it doesn't, it may come off and hit someone in the head.

Precision in forming the loops is critical to having things work well, and makes wrapping a whole lot easier. Use the round-jaw pliers ONLY!

For solids, you must wrap with copper and solder.

The attached picture is of a .010" diameter line as used in Mouse racing. These are the second most difficult line terminations to make. The most difficult are F2C lines which have some additional constraints. Larger sizes are easier, but the techniques are the same. I have a sequence of photos of building these Mouse lines, so if you have other questions, there are a few more "thousand words" available.

Dave

PS--As best I can dig up, guys took the terminology for a button termination, which usually was buried inside a wing and since they were preparing the flying lines the same way--even though they were no longer using leadouts and buried buttons--they started calling them "button bellcranks."  Literally, line buttons resembled old fashioned shirt buttons that were not attached to the shirt. I still have a couple of planes with buttons on the end of internal leadouts. Nowdays, racers often figure out how to skip the buttons and get access to the bellcrank via a hatch and run lines all the way to the 'crank. There are pros and cons to that, but that's a different story....