.015 x 62' or 65'.  I've been using LA 46 with these lines all season; happy.

I lost a nice Nobler / Fox .35 to using .012 lines.  Granted, they were not in great shape, but the LA .46 outclasses a Fox .35, too.  I'd use .012 on .049 - .15, but not more.

Peter

On a standard Twister. Am thinking of .015, or would .012 suffice?  Will go with 7-strand stainless.

   I think you will be probably be beyond .012-.015 break point (40 ounces), and even if you aren't, use .015s anyway. Length, make 62-64 eyelet-to-eyelet. That's what I would use if I was flying a Twister with a 25FP - and it flew very well that way.

   It is a slightly irritating feature that the line size break point are right in the middle of the ranges of the associated model weights - 40 is around a typical weight for "35-sized" models and 64 is right smack in the middle of the range for 40-60 tuned pipe models. So you can be tempted to try to use, say, .015s on your 63-ounce airplane, but can be thwarted by a slightly mis-calibrated scale, or a minor trim adjustment, and go over. That's just the way it worked out when you run the numbers and make the margins about the same at every size change.

Don't be like one well-known modeler and sportsman, and remove all the tipweight and noseweight for the weigh-in, then put it all back for flying. And, he got caught, anyway.

     Brett

Very good, and much obliged, gents!

Brett: Makes a dude wonder how that "feature" got built into the range of weight and line diameters?!

   We know exactly why. The pull test itself (the 10Gs) is about 4x the normal pull of a stunt plane, which is around 2.5 Gs., that is normally shared by the two lines in a test, When a single line lets go, all the pull is applied to the single remaining line, so it has been tested to ~2x the load it will see in a failure, which we thought was a good margin.

   When it came to determining the line size breaks, we used the accepted industry standards for line test strength, so that the lines you have to use have a nominal test strength of what it sees in a failure with the similar margin. For example, suppose you have a 63.9999 ounce airplane. You select .015 lines, and pull test ~40 lbs. so each line sees ~20 lbs in a pull test. The nominal industry standard for the test strength of .015 2-strand stainless-steel lines is about 40 lbs. So even during a pull test, you have a margin of about 2 over the expected lowest-failure-tension. This sort of margin over the test strength is intended to reduce the possibility of fatigue failures - because you don't want to repeatedly test something to exactly its rated strength over and over.

   Of course, the sizes were arrived at by doing this in reverse, calculate the pull, throw reasonable (but not crippling) margin on everything. It just happened to fall right in the middle of the current range of airplane weights.

The airplane pulls about 10 lbs total (2.5x4 lbs). That means that after a failure. your .015 lines see about 10 lbs, which is half the pull test and 1/4 the nominal expected strength of the line.

   Having said all that, even if you could guarantee that you would never go over the break point in weight, you might try the next size up lines anyway, for performance reasons.

    Brett

   

Brett: Maximum wow on your information-packed explanation. Not only do you awaken a few sleeping brain cells here, but you expand the on-line archive for future C/L fliers.

   Thanks!  Of course, a far better solution to the line-diameter issue would be to not have one. There's no good reason (that I can think of) to specify the line sizes at all. I would be perfectly OK with just specifying the pull test and have no other requirements. Last time I tried that I was told that there was some insurmountable insurance/legal reason why it could not be done (by GMA, after having discussed it with Carl Maroney (former AMA big-shot)). That was around the same time the AMA Safety Code got altered to include the bit about "if you don't know, use the stunt pull test", and part of the same discussion. It started when I pointed out that all it said at the time was "must perform a pull test" which didn't say how much.

    Brett

p.s. Steve Yampolsky said he was going in a proposal for no line requirements, and I would recommend my rep to vote on it. Note that this also solves the issue with fishing line - no knot requirements, no phony "traceability" requirements, if it managed 42 lbs 15 minutes ago, it should handle 8 lbs now.

Dave I use 63' handle to center line on my Twister/LA46 with .015". It gives me a nice stunt run with laps left over on a 4oz tank with Randys 11-4.5 TT prop.


Motorman

Just an observation.  I have been flying a Twister to keep in shape since October while I build a real airplane.  I started out on 65' lines but I have since dropped all the way down to 58'.  It flies much better which means I fly it much better.  I think it was a visual thing of having this itty bitty plane so far away.  Fantastic plane.

Ken

....you might have to start moving your hand half a lap before you want it to turn.

    Brett

That happens anyway when you hit 70!

Ken