Control Lines Length Selection

[Matt Piatkowski]

Hello,
A stunt model weights 20.5 oz RTF. and is slightly larger than typical 1/2 A but smaller than Ringmaster, having 42" span and 380 sq. in. wings area.
The span of the model = 37 " and the wings area ( there are no flaps ) is 296 sq. in.

Estimated speed ~ 59 - 66 ft./sec.

What should be the lines length to start with? Are 45' long and 0.012" braided ok?

50' will give more reasonable lap times but, because the model is so light, there will be most likely not enough centripetal force ( only around 3.5 lb. in level flight ).

Thanks,
Matt

[Tim Wescott]

If you start with 50' and you know they're too long, you can shorten them.

It's harder to go in the other direction.

[bob whitney]

  u didnt say what engine is in it

[Bill Johnson]

If you start with 50' and you know they're too long, you can shorten them.

It's harder to go in the other direction.

Plus you didn't state if you have any rudder offset, engine offset, leadout positioning to give some yaw. All those will increase line tension.

I'm with Tim.

[Peter Anglberger]

If it is a 1/2A 0.012 lines are probably too large in dia and I will let the 1/2A experts chime in on what you should use. BTW it is 1/2A powered I reckon it will not matter what you do at 20.5 oz. If it were a .15 powered model I would say 50 ft eye to eye absolute MINIMUM. I fly an Aldrich Peacemaker powered by a 2.5 diesel (1955 Burford Sabre Mark 4) on 58 ft eye to eye. The longer the lines the larger the hemisphere to fly the tricks in, and you can keep the speed up without having to spin around too fast. My Peacemker still does 4 second laps on those lines.

Cheers,
          Peter

[Randy Cuberly]

Your speed is roughly round 35 mph.  With a 20 ounce airplane I think that's a bit too slow for 50 ft lines 42 ft might fit a bit better.  I've flown 20 ounce Ringmasters on 60 ft lines at about 54 mph OK.   But slower than that is too slow.  That would equate to about 45 mph on 52 ft lines.

If it were mine to try I would expect about 42 ft line would work OK, but I certainly can't disagree with Tim in that starting with 50 ft and cutting them as required is a reasonable idea.  I would however be sure to test fly it on a day when there was little to no wind.

Like others here I would very much like to know what engine you are using.

Randy Cuberly

[Ted Fancher]

How much does it weigh?

[Target]

If I'm not mistaken, he says it weighs 20.5 oz in the original post.
HTH,
Chris