Control Lines For all you fly-by-wire fanatics!

Line dia. vs length question

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Old 10-22-2011, 03:53 AM
  #1
gene6029
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Default Line dia. vs length question


I have the bug to get back to flying C/L again, mostly because my grandson likes it more than R/C. I flew c/l when i was a kid and more recently with the grandson, but it was allways 1/2a stuff on dacron lines. My question is what are the recommended dia & length lines for the following size models..... .049.... .15-.19..... .35-.40 ? Space is not a problem, & if i'm starting to buy him stuff i'd like to get it right. For some reason he really likes the C/L models better than flying R/C & i'm not discourageing him.....Gene
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Old 10-22-2011, 04:51 AM
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R8893
 
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Default RE: Line dia. vs length question

.15-.19 engine use 0.012" diameter lines 52.5' long. .35-.40, 0.015" diameter 60' long. The line lengths are tradional and probably were derived from the speed and racing events. 7 laps on 60' is exactly 1/2 mile as is 8 laps on 52.5'. Makes the math easier to calculate speeds. I have not flown any half A since I was a kid.
Chuck
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Old 10-22-2011, 05:19 AM
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Default RE: Line dia. vs length question

Those line diameters should be good. Length depends. Some C/L sports have lengths determined in the rules. For sport and aerobatic flight it is more like whatever gives you lap times and line tension that you like. For aerobatic competion flying, people seem to go for slightly over 5 seconds per lap.

I hear the smallest steel lines are sometimes difficult to handle (like .008" diameter). Many fly .049 engines on fishing lines but you need to get the right choice there too, in diameter and brand. Stretchy lines are not good for control...
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Old 10-22-2011, 05:35 AM
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Default RE: Line dia. vs length question

Wow! that was fast, Thanks.....Gene[8D]
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Old 10-22-2011, 05:59 AM
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Default RE: Line dia. vs length question

Gene

.012 dia. lines are good on airplanes that weigh up to 40 oz. regardless of engine size. These days they must take a 10g pull test. You can look up the rule book on the AMA web site showing airplane weight and line size dia.
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Old 10-22-2011, 08:01 AM
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Default RE: Line dia. vs length question

The engine has a setting at which it runs best, determined by needle, prop, fuel, etc, etc. The airplane has a speed at which it flies best. Having accomplished that, you want a line length which gives you both comfortable tension, and comfortable lap times. A rough rule of thumb is that a one foot change in line length gives a 0.1 sec change in lap time.
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Old 10-22-2011, 09:17 AM
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Default RE: Line dia. vs length question

No one said .049 size lines.  A low powered Baby Bee would likely go .008" to .010"  @30' to 35'.  If you have a Tee Dee, Norvel or Fora, 42' would be standard.  A pull test is always recommended before each day's flying or after each crash.(if that would ever happen)  There is some stainless steel fishing line that seems good for 1/2 A.  I like a .09 to .15 motors myself for economy and more importantly for kids, they won't get away on them if the lines go slack and pull the handle out of their hands.  A thong is a good idea.  I had a sore shoulder for a couple of days when a .40 plane recovered from slack lines and I am a fairly big guy. It didn't hurt at the time though.  .049 motors are not too good in the wind and are kind of finicky sometimes unless you get a Fora or something like that. 
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Old 10-27-2011, 08:57 AM
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Default RE: Line dia. vs length question

Sig used to sell .008 stranded cables for 1/2A flying. They are a lot easier to handle than solid .008 lines at 35 to 42 feet. Most Cox, Norvel, Wasp .049 to .061 engine sizes would be fine with those lines when using a nominal sport power setting on a trainer like model. I always liked the Carl Goldberg Lil' Wizard and Sig 1/2A Skyray for 1/2A trainers, they have a nice size wing area and lots of tip weight.
Chris...
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Old 11-19-2011, 04:53 PM
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Default RE: Line dia. vs length question

For .049 size models Ihave found Spiderwire a lot less troublesome than messing around with .008". It's a lot lighter than steel lines but (in my experience at least) a little bit more "Draggy". You need to use specific knots to tie it otherwise it can pull through under load, the Palomar knot seems to work well (Google it if your not sure how to tie it). Ihave flown 049 size models on 15lb with no issues. Make sure you get the braid though not the monofiliment. Available in plenty of colours (So easy to see and not trip over) and very "robust in use", No chance of kinking even if you step on it or manage to get a knot in it.

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