Line length

[Larry Wong]

What determines the line length of a stunt plane? Speed? Or ??

[Tim Wescott]

Your question is a bit open-ended, so I'm going to start by speaking my native language, Smartass.  I'll try to bring it around to plain English at some point.

Line length is determined by how long the lines are.

But you probably mean to ask how you determine what the best line length is for a particular plane.  That's a harder question, because there's lots of variables, and to some extent it depends on your preferences.

For a typical "top dawg" 700 square-inch stunter weighing 3 1/2 to 4 1/2 pounds, you want lines that are pretty close to the maximum allowed size (which is 70 feet, not from eyelet-to-eyelet, but from the fuselage centerline to the handle grip).  Personally, I think that the reason that the top dawgs are mostly flying airplanes that size, and not larger, is because that's about the biggest reasonable size of plane that you'd want to fly on that size of lines.

Lighter planes seem to like shorter lines.  Smaller planes seem to like shorter lines.  Planes with wimpy engines (at least if they're light enough) seem to like shorter lines.

I tend to run longer lines than most of my peers.  I also tend to build heavier.  I believe there is a definite correlation there.  For the same design, a heavier plane needs more airspeed to handle well.  Long lines will give it more airspeed at the same lap time.  Also, for the same lap time longer lines give you more centripetal acceleration resulting in more line tension -- this means that if all else is equal, you can lengthen the lines and get both a higher airspeed and a longer lap time.

My personal guide would be:

• 700 squares or up, start with regulation max lines, and experiment with shorter lines in 4" increments to see if you like that better.
• 550 squares ("Nobler sized"); start with 65' lines and try shorter to see if you like it better.  If you shorten the lines and you're just not happy, try longer lines
• 450 squares (Skyray); start with 60' lines and try shorter

You can also get on the Open forum and post a question about your specific plane; i.e. "What line length for a Nobler?", then in the body of your post say how heavy it is (or you expect it to be), what engine (a Fox 35/Nobler will want much shorter lines, for instance, than a Nobler with a 46LA), and even your experience level.  Even though I fly expert, you may well see me doing that.

[Ken Culbertson]

Tim's reply pretty much covers it except for the personal preference part.  I am one of those strange people that doesn't rely much on timing to fly the pattern.  Maybe that is bad but I learned it that way and I am frankly too old to be changing now.  I "see" the maneuver and fly the plane to what I see.  So, what does that have to do with line length?  My competition (summer) ship is about 42" long but I fly profile and practice in the off season with a much shorter modified Twister that I have trimmed to fly like the bigger ship in every way but size.  Until recently, I flew it on the same lines as my PA ship (64') and adjusted the motor (electric both) to give me the same (5.4) lap times.  Then one day one of the other fliers suggested that I shorten my lines. I told him why I was doing what I did he asked me if the plane looked the same that far away.  Never thought about that.  I shortened them and sure enough I flew it better. 

My point is that there is a whole lot of personal preference that goes into length and the only way to know is to experiment.  I like the plane to pull a lot and longer lines will do that.  I also tend to build heavy like Tim and more speed does help there too but I have also found I can track out of corners better on shorter lines.  Less stretch, less whip.  Perhaps 64' is *my* compromise.  Since there is no safe way to make lines longer, buy them big and cut them down till you hit the sweet spot.

Ken

[Randy Powell]

Wow, Timmy, your smart.

[Tim Wescott]

Wow, Timmy, your smart.

No I'm not.  And it's "you're".

[Tim Wescott]

My point is that there is a whole lot of personal preference that goes into length ...

If I didn't get that across in my post, allow me to say yes!.  Yes there is.  Which is why you should experiment.

[peabody]

Brett likes shorter, heavier lines....and his results speak for themselves.

Lines are a tuning tool.

Just because you have the latest blechfire 90 doesn't necessarily equate to 70' center of plane to center of the handle.

[Peter in Fairfax, VA]

There are a lot of things that interact to determine line length.  To me, leadout position, pitch balance, roll balance, yaw thrust angle are also factors.

Generalizing, my experience is that if the plane seems to light going into wingovers, I shorten the lines to make myself more comfortable.  Okay, it should be "too light," but needed something for the grammar police to cite.

Right now I have a Brodak Cardinal (profile) that pulls hard in level flight with its LA 46 on 62'5" lines, eye-to-eye.  I removed the outward thrust, moved the leadouts forward and moved the balance back.  I like it a little better but will try 65' lines next.

Peter

[M Spencer]

" What determines the line length of a stunt plane? Speed? Or ?? "

Speed ? Nitro ! . knactually , nitro can keep it lit & turning , so has its uses .

WIND would be the biggest factor . A FSR / 35S Noblerish would be too good on 70 ft of .012 when its blowing . Something else in the calm tho.

Then 55 Ft. eye to eye of .018 steel stranded wire might sound a bit off , but itll steer in a gale . Twice what'll turn .012 into rubber bands ,
Or .015 simlarly.

Good test is two nails say 6 inch apart , in the top of the fence. etc.

Hook up your wires & handle . Lean Back . Give the hhandle a few wiggles ( up & Down control ) .

If it jiggles back , you can see where youre getting problems , in the air. at comparable pull .

As they tend to pull away when its blowing a tad .
Thus the feedback is , ' it Pulls THIS MUCH ' . Hook it up as above & try snatching up & down .

Thus with the Five Ton Wire to handle the Gales , you cant go out quite as far , to the Aeroplane .
Unless you put a 90 in it .