Line length

[David Fretz]

What recommended line length for a Vector ARF with a OS 40 LA.

[Jim Mynes]

60 feet eyelet to eyelet works on my Vector.

[David Fretz]

Thanks Jim

[Tim Wescott]

I like to use longer lines -- this lets you get a higher airspeed at the same lap times, and more actual room to get the same-appearing maneuvers.  But then, I have a stable-full of porky airplanes -- I suspect a really light plane will like to fly on shorter lines.

Bottom line -- 60' eyelet to eyelet (probably 62 1/2 to 63 "official" feet) should be fine, but you might want to make up a set of lines 2 feet longer and try them out; if you like it enough, go out two feet more.  There are folks that suggest trying line lengths in 6" increments -- I should probably start doing that myself.

[Ken Culbertson]

I like to use longer lines -- this lets you get a higher airspeed at the same lap times, and more actual room to get the same-appearing maneuvers.  But then, I have a stable-full of porky airplanes -- I suspect a really light plane will like to fly on shorter lines.

Bottom line -- 60' eyelet to eyelet (probably 62 1/2 to 63 "official" feet) should be fine, but you might want to make up a set of lines 2 feet longer and try them out; if you like it enough, go out two feet more.  There are folks that suggest trying line lengths in 6" increments -- I should probably start doing that myself.

I am running a 52oz ship on a OS46LA.  I started at .015 60' and it pulled so hard overhead (like that is bad?) that I tried a set of 62'.  Still had better than normal tension.  Just got a set of Ukrane .0165 that feel better at 63' than the 62' .015's.  Wish I had gone to 64'.  You can make them shorter, you can't make them longer!  Got a .0145 set on the way.  I will move out to 65' with them.

This is a personal thing but I much prefer the extra space you have on maneuvers.  I will go as long as I can till it starts falling in overhead or I run out of tip weight.  But that is just me.

Ken

[Tim Wescott]

...  I will go as long as I can till it starts falling in overhead or I run out of tip weight.  ...

If you assume a steady airplane speed with respect to the ground (which isn't a good assumption, but hey -- it makes the math easy!), then for the same lap time you should get a stronger pull with longer lines, because you have to fly faster.  So unless the engine is running out of poop to keep the speed up in the overheads, longer lines should equal more pull.

[Paul Smith]

The official and only accurate way to measure lines is from the grip of the handle to the centerline of the engine, and the overall maximum length is 70'-0".  This "eye-to-eye" stuff neglects the lineouts and handle, which are significant.

For stunt, the longest that your plane will pull give you slower lap times and more maneuvering room.  The corners look sharper and there's more straight in the squares.

For anything that involves speed, the shortest you can get by with is best.

[Ken Culbertson]

If you assume a steady airplane speed with respect to the ground (which isn't a good assumption, but hey -- it makes the math easy!), then for the same lap time you should get a stronger pull with longer lines, because you have to fly faster.  So unless the engine is running out of poop to keep the speed up in the overheads, longer lines should equal more pull.

It is gravity when you are overhead.  Everything, including tip weight is trying to fall down.    I like to fly about a 5.3 to 5.4.  Right now on 62' I am flying 5.2 which is fast for me but I have gotten used to it so I will probably up the RPM a tad.  However, the reduced drag of the Ukraine lines (the line rake seems to be less but that may be the shiny copper tricking my eyes  ) might produce the same lap times with the same setting.  And with all of this engineering, trimming  and practice I will proudly go out next week and place last at the Gieseke Memorial.  Isn't this the greatest sport/hobby there is!

Ken

[Tim Wescott]

It is gravity when you are overhead.

Well, yes and no.  If you were going a steady speed (which you don't) then with a mass that's going around a 62' radius of curvature* will pull about 2.8 g's.  That leaves 1.8 over for line tension at the top of the circle.  You'd need to slow down by about 66% (from roughly 51 mph down to a bit under 31 mph) to get to zero line tension -- although you'd probably be getting a wee bit concerned** before things got to that point, particularly in a stiff wind.

* This sounds odd because I'm being precise in my language -- just figure "rock on a 62' string" if it makes no sense to you.

** Mike Haverly fell in the contest this weekend in Classic, because a bad motor run made his Chizzler go slack on the lines, and losing his balance when he was trying to keep line tension.  He did a very good job of not crashing while lying on his back and flying his plane.  In spite of a reputation for graciousness, he was very gruff with me when I complimented him for having the foresight to fall on his a** to save his plane.  Go figure.  I had a similar slack-line event in Expert, for similar reasons, but I was able to just let it fly itself out until it hit the lines on its own.

[RandySmith]

What recommended line length for a Vector ARF with a OS 40 LA.

Hi David

That setup works  very well  at  63 feet center handle to center airplane thrust line

Randy

[FLOYD CARTER]

Instead of wasting time and money with several sets of lines in 12" increments, you can get the same effect with just one set of lines.  Try some maneuvers with your arm pulled back.  That will decrease flight radius by about 3 ft,.  Likewise, try walking in a small circle (towards plane).  That should increase flight radius by another 3'.  Once you have the flight radius you like, then make up a set of lines to match.

[Ken Culbertson]

Instead of wasting time and money with several sets of lines in 12" increments, you can get the same effect with just one set of lines.  Try some maneuvers with your arm pulled back.  That will decrease flight radius by about 3 ft,.  Likewise, try walking in a small circle (towards plane).  That should increase flight radius by another 3'.  Once you have the flight radius you like, then make up a set of lines to match.

Neither of those will tell you how the plane reacts to the increase/decrease in line drag/weight.

[john e. holliday]

Really!   If you keep your hand close to your chest during a maneuver and the go arm out on the same maneuver you should feel and see a difference.   Same with walking a circle.   I can shorten landings on a circle by walking toward the plane after engine quits or make it go further around the circle by walking backwards thus shorting the circumference of the circle.  Bur in all cases the airplane must b flying the same air speed not ground speed.

[Randy Cuberly]

Just use what Randy Smith told you to above and go fly.  You'll be very happy!!!

Randy Cuberly

[Ken Culbertson]

Really!   If you keep your hand close to your chest during a maneuver and the go arm out on the same maneuver you should feel and see a difference.   Same with walking a circle.   I can shorten landings on a circle by walking toward the plane after engine quits or make it go further around the circle by walking backwards thus shorting the circumference of the circle.  Bur in all cases the airplane must b flying the same air speed not ground speed.

We are talking past each other here.  I am not talking about the size of the circle the plane flies, just effect of the length of the lines.  Pulling in does not change the length, weight or most of the drag of the lines but it does change the size of the circle.  Walking towards or away does not change the size of the circle the plane is flying, it just moves it's center.  What you are doing on landings is appropriate, I do pretty much the same thing but it is not why I am tinkering around with line length.  I want better squares and more time to hit bottoms.  My reaction time is not what it was when I was 40.  Just going from 60' to 62' gave me enough extra time to start hitting 5' on square bottoms consistently.  I am also farsighted so having the plane another 2' away really helped.

Cheers - Ken

[Brett Buck]

The official and only accurate way to measure lines is from the grip of the handle to the centerline of the engine, and the overall maximum length is 70'-0".  This "eye-to-eye" stuff neglects the lineouts and handle, which are significant.

    "Accurate"? My lines are the right length to about 1/16th of an inch, and are matched within about .005? How is measuring in the irrelevant way (for stunt) any more accurate? My 63' lines are really 63', just like David's and just like Ted's and just like Randy's, and everyone else in stunt. Have a line failure - just get anyone else's, they are the same.

     The rule of thumb I use and many others use is to use the *shortest* lines you can get away with/tolerate, because the shorter the lines, the better the precision. I *could* fly on 85' lines if they would let me, the airplane will certainly pull those lines, by why would I want to?

     Brett