Line length as a trimming tool?

[Dane Martin]

As an attempt to get ready for the Palmer, Kristina and i went out and flew many flights back to back with the twister. The very first flight, i hated the handle feeling. Changed that for the second flight. The Reverse wing Over came out much better, so from there the outside stuff felt much better.

It felt like i was running out of room to make a maneuver all the time. I was at 5.12 sec laps. So i changed to longer lines. Third flight i switched to 62' lines. This felt like the best set up to me. I flew every maneuver really big, because it was windy as can be. So the longer lines helped, i think.

Question is, how do you actually know what is a proper line length. I've been following Paul's trimming guidelines, but see nothing about line length. Is it just feel?

Btw, thanks Paul! Very nice of you to take all that time to develop a trimming tool for us rookies!

[Tim Wescott]

I asked Paul about line length at a contest, and he kinda shrugged and said "it's a personal preference".  He claimed that he was going to touch on it in a then-future column (it as at the October contest in Salem, but for the life of me I can't remember if it was 2013 or 2014).

Personally, I run the longest lines I think are reasonable (and longer than a lot of other people do), and I adjust the plane from there.  I have yet to say "oh dang, I think these lines are just tooooooo long" and shorten them up.  I feel that it lets me get more speed and line tension for the same lap time, and open up the maneuvers from the plane's point of view while keeping them reasonably tight from the judge's point of view.

For what it's worth.  Product photo is for illustrative purposes.  You mileage may vary.  In the event that any of the above-mentioned symptoms occur, see your doctor.

[Dane Martin]

I like what you're saying to me right now Tim. I think everyone can agree 62' lines are fine on a twister. Overhead tension was great, so I'm at least close.

[Tim Wescott]

I flew my 53 ounce Twister on 65' lines eyelet-to-eyelet.  It seemed to work nice.

On the other hand, I was given a Twister that flew great on 59' lines.

[Steve Helmick]

Bigger engine (and prop) = longer lines. Lighter airplane = shorter lines. Somewhere in there, throw in what you like in the way of line tension. I kinda like quite a bit of that. Pete Peterson flew my SV-11 once, and hated the "heavy" pull. I didn't think it was excessive at all. I should drag it out and fly it, just to refresh my memory.  Steve 

[Brett Buck]

I like what you're saying to me right now Tim. I think everyone can agree 62' lines are fine on a twister. Overhead tension was great, so I'm at least close.

   Make up a set of 63 and 64 and see how they work. Change the lines, retrim to ideal for that set, then compare the performance.

   Many times, the "running out of space" feeling can come from excessive compliance in the handle or lines, or the CG too far forward. I would highly recommend the longer lines as an experiment, but if it just feels cramped, try moving the CG aft a bit at a time. My airplane is set up to feel best for smaller maneuvers, and if I want to fly slightly larger (closer to what mode people do), it just seems to "wander" in the maneuvers - which can usually be improved by a small CG shift like going from a small aluminum prop washer to a large steel prop washer. Same might happen going from 62 to 64', it might tend to not feel locked in without a CG shift.

    Brett

[Dane Martin]

Excellent points Brett. I don't want to drone on and on and bore everyone.... But.... I'm right at that point where i like everything up to the corners. I'm too sharp in the corners. I need to finesse them a lot. However! I'll note that that's pulling out of a down line is when that is noticeable. I assumed it was because of the wind. It was bad today. I'll try again tomorrow., hopefully the wind will die down.

So going by the chart, the cg being forward would help with the corners, but i think I'm probably as far forward as i wanna go. I was going to move the elevator horn link to be one hole farther away from the surface. (longer horn).
Then i could probably shift it back.

Thanks for the tips guys. At work, i call this telephone troubleshooting... But it's helping, so i appreciate it guys.

[Tim Wescott]

<snip>

I'm too sharp in the corners. I need to finesse them a lot.

<snip more>

So going by the chart, the cg being forward would help with the corners, but i think I'm probably as far forward as i wanna go.

<snip even more>

Re-read the text of Paul's article.  If everything else is good but the corners are just too sharp you may want to keep the CG where it is and narrow up the handle spacing.  After you may even end up wanting to move the CG back (but I can't know without hearing more).  Handle spacing, CG, prop diameter, and flap to elevator ratio will all deaden or liven up a plane's turns, but each of them has other effects, too -- you want to adjust the right thing, in the right direction.  I wouldn't worry about the last two of these at this point, though -- CG and handle spacing are the primary influences here.

Don't be afraid to use a handle spacing that's way different from anyone else: for any given plane I probably have the lines more closely spaced than anyone else in the Pacific Northwest; contrast that with John Leidle, another Expert pilot around here who uses a six inch spacing on a plane with an otherwise standard set-up.

[proparc]

One thing you guys should do is, to think in terms of line length as, from the center of the fuselage to the center of your handle. When I make up my lines, all I am thinking about is that "center to center" distance.  Also this may sound strange but, I never think of my line length as a "plus" length. I ALWAYS think of it as, some distance down from the max of 70'. Minus some distance from 70' max, or right at it.

When I went to the Saito 72, line length started to become critical. I had to change my thinking about my line length to handle the power and the relentless drive of the big block.

[Dane Martin]

Lol, i haven't used my saito 72 yet! I think Pat Johnston said something about a plane to handle that beast. I'll call him and ask about that idea. My 800+P from Pat ran great on an os52 fs on 70 foot from center of plane to handle.

[proparc]

Lol, i haven't used my saito 72 yet! I think Pat Johnston said something about a plane to handle that beast. I'll call him and ask about that idea. My 800+P from Pat ran great on an os52 fs on 70 foot from center of plane to handle.

One of the biggest mistakes is thinking you have to have a big plane for the 72. The other big mistake is that, you HAVE to use a big prop. The 72 will do a fine job in a 700sq ship. I flown with a little as a 12X6 APC on it, and the performance was kickin. Once properly setup, few packages can match it for wind penetration. One thing for sure is that, 70 feet C. to C. is going to be the minimum.

[Don Hutchinson AMA5402]

Be aware, AMA competition rules specify 70' maximum line length, C  to C.