Hi All:

A vintage combat plane question:

How does one adjust the recommended line sweep and wing tip weights of the combat planes designed during the years when .015" lines were the rule so they will fly straight and true during turns with .018" lines? 

FWIW: I long ago switched over to .018" lines to fly my vintage combat planes*, mostly with good success. However, some of them have dragged their outside wings during maneuvers, which tells me too much wingtip weight for the lines.

* Way back when, I have had line breaks with .015" from simply flying tight maneuvers with a very fast and tight turning airplanes. I have had ZERO such line breaks since switching to .018" after the AMA combat rules changed to .018" lines.

As for line sweep:

I THOUGHT I read somewhere that adding about 1/2" of sweep to the lines of an .015" combat plane would put you in the ball park in regards to added line drag... but what about wingtip weight?  How do I determine how much wingtip weight would be required for a vintage combat plane to be flown on .018" lines?  Example: The Combat Cat was designed for .015" x 60' lines. The plans call for 1 oz. of wingtip weight.  Should this be adjusted for the .018" lines, or would adding a bit more line sweep do the trick?

Help me Obi Wan... for you are my only hope.

Andre

Thanks Ken.  That pretty much verifies what I recalled reading so many years ago.

I have been adding 1/2" sweep for decades and I thought I was good to go.

However, in regards to the above mentioned Combat Cat. I built mine thusly:

* Added 1/2" of sweep to the leadout location.

* Added 1 oz. of wing tip weight AS THE INSTRUCTIONS CALLS FOR.

Problem is, the plane flies good and straight in level flight, turns nice and tight... BUT... it drags its outboard wing through inside/outside maneuvers.  This indicates to me (and those that watched) that the kit plans call for TOO much outboard wingtip weight... but I'm using heavier lines than the airplane was designed for??  Weird.