ajustable leadout questions

[scott matthews]

Going to start building the wing to a Galaxy profile,I bought the adjustable leadout guide from Brodack. My question is that the leadout has only 1 plastic slider with both line guides running thru it, the distance between these holes is alot smaller than the traditional spacing on the plans is this normal? My other question is when elongating the holes in the ribs how much material do you remove (because I do not know how far you move the leadout guide fore and aft for trimming). I am assuming that when using this guide that you set its initial location in between the lines on the plans and then tweak it from there.Thanks for any advise.

[Leester]

Although it will be a little awkward you will probobly have to wait until the wing is built to get the correct amount removed from the wing ribs. I usually put the self adhesive sand paper on a piece of 3/8" copper tube and sand until there is plenty of clearence for the lines. Yes to the question on the line slider spacing it works fine.

[john e. holliday]

Mark the wing tip as to where the leadouts would normally be located.   Center the adjustable guide in the center of the two points.  If you do a search on here you should find some posts on adjustable leadout guides.   

[Tim Wescott]

What I would do:

Use Line III to find the correct leadout position from the design center of gravity and your guesses about line length and airplane speed.  If you think you're going to stick with that CG, then center the leadout guide there, or maybe bias it with 1/3 movement forward and 2/3 back (I don't know how much travel the Brodak leadout guides have).  Sketch the leadout guide on the plan, and get an idea of the front most possible leadout position, and the rear most.  Draw lines from these positions to the holes in the bellcrank, and now you know how far forward and back the slots in your ribs must extend.  Don't forget to relieve your spar appropriately as well.

[Bill Little]

Hi Scott,

The guys seem to have covered it well.  The C/L of the LO guide set on the C/L of where the originals are shown.  I have never seen anyone have to use the full length of the adjustments the LO guide provides, unless something was done really wrong in construction.

If you get to the point where you have flown a few thousand C/L flights, successfully, you could probably get away with putting them almost anywhere along the guide and still have the plane in one piece  once the engine quits.  But, if you set it on the C/L for the first flight, and the CG is where it should be, then you are pretty much assured of a successful flight at that point.

My guess is that if you have to move the LO guide more than a 1/2" either way from the suggested starting point, something is way wrong...........   Usually we are talking around 1/8th" movement at a time.  And for beginning, or Sport flight, maybe no movement at all to start with.

Big Bear

[Tim Wescott]

My guess is that if you have to move the LO guide more than a 1/2" either way from the suggested starting point, something is way wrong...........   Usually we are talking around 1/8th" movement at a time.  And for beginning, or Sport flight, maybe no movement at all to start with.

I dunno.  Old-time control line plans and new 'trainer' type plans (i.e. the Sig Skyray) put the lead outs a lot farther back than current stunt practice seems to indicate is correct.

According to Line III, I need to center the leadouts on my Skyray less than 1/4" back from the original front leadout position, moving the center point forward by about an inch.  I did so just recently, and the plane flies a lot better in the overheads as a result.

[Bill Little]

I dunno.  Old-time control line plans and new 'trainer' type plans (i.e. the Sig Skyray) put the lead outs a lot farther back than current stunt practice seems to indicate is correct.

According to Line III, I need to center the leadouts on my Skyray less than 1/4" back from the original front leadout position, moving the center point forward by about an inch.  I did so just recently, and the plane flies a lot better in the overheads as a result.

Great!  Glad you got it right!

Big Bear

[scott matthews]

Thanks guys for the great advise, I tried running line III on my computer and it says its not compatible . My computer is running windows 7 and has a 64 bit operating system how can I get this program to work.Scott

[Bill Little]

Thanks guys for the great advise, I tried running line III on my computer and it says its not compatible . My computer is running windows 7 and has a 64 bit operating system how can I get this program to work.Scott

Sorry, Scott, I cannot help you there!

(plus never used Line II or III or any of them, not to say you shouldn't)

We didn't have it for the first 40 plus years of CLPA.............

Big Bear

[Tim Wescott]

Thanks guys for the great advise, I tried running line III on my computer and it says its not compatible . My computer is running windows 7 and has a 64 bit operating system how can I get this program to work.Scott

Try spelunking through the manuals, or web surfing -- I dimly remember that there's a 32-bit compatibility mode for Windows 7.  I wouldn't know -- I abandoned Windows some years back and use Linux for nearly everything I do.

[Steve Helmick]

Remember that LO position is related to speed. If your model was designed to do stunt and combat, then in theory, there would be two LO positions shown, one for fast, one for slow.

For stunt, the general rule is 3/4 to 1 inch behind the CG (to the center of LO slider). The problem is that some plans may not show the CG correctly (Flite Streak, I hear), while others may suggest a very forward CG location for first flights, so you'll need to move the CG aft, and thus the LO's also.

If you were to post the half-span, expected speed (maybe 60mph for a profile used for stunt, or 80mph for the same plane used for combat), line size and expected line length (ctr. to ctr.), then somebody could run those numbers through the Line 1, 2 or 3 program and give you an idea. It will be related to the CG, however.
  Steve

[scott matthews]

Thanks for the advise on the program. my galaxy plan does show the CG on the side view so I will start with the leadout guide in the center of the existing plans and try some flights . When I go and fly this plane will I be able to easily tell were the nose of the plane is at will flying or do I need someone to spot this from my starting point. If anyone can run this line III program and has the time I plan on flying my Galaxy with a new OS 25LA engine on 60" lines that are .018 thick with 10% Wildcat fuel. Thanks and happy building till the weather improves. Scott

[Leester]

.018 lines are way to much use .012 or .015 depending on the planes weight.

[Tim Wescott]

I'm a rank beginner at CL stunt, but this matches what I know from RC airplane design and it's been recommended to me multiple times.  Besides, it's written by Paul Walker, so it can't possibly be wrong.

http://www.vicstunt.com/Patterns/TrimChart/TrimChart-Content.htm

Bottom line on leadouts: too far back, you get good tension on the level but it really drops off overhead.  This is what I experienced just yesterday with my newly-modified Skyray: without really trimming anything beyond moving the lines forward an inch, my overheads went from uncomfortably light but still controllable to firm, if still noticeably less than on the level. 

The chart doesn't say what happens if they're too far forward -- I get the impression that there is no "right", just "less wrong".  And everything interacts, so you can't just stop when you think you're done.

[Jim Thomerson]

If you get the leadouts too far forward, you get yaw in when you give control on which ever is the front line.  The neat things about adjustable features is that you can get them just right, or you can experiment around and learn what effect each position has.  This is good to know. 

[Bill Little]

OK,

I went and dug out my May 1991 issue of Flying Models.  What, may you ask, is the importance of THAT issue?  Well it is the issue that contains the build article on the IMPACT.  Int that article is probably the BEST "trimming treatise"ever written in a model magazine pertaining to CLPA.  I don't know about anyone else, but an argument could be made that the Walker Trophy could possible be named for Paul instead of Jim because Paul has won it some many times! LOL!!

There is a flow chart which I believe is the one copied on the  Vic Stunt site.

I have never used line III, partly because I am lazy, but mainly because I have done what Paul suggests and it has worked every time.

The following works first time, every time and needs nothing electronic (like a computer for line III) to carry out!

Pre-Flight Trimming: Prior to the initial test flights the trim can be adjusted into close range by a few tests.  Make sure the C.G. is located according to the plans and certainly no further aft.  Adjust the leadouts so that they are 1/2-inch aft of the C.G. location.  Now turn the plane upside down and place it on your padded bench.  Gently push the inboard wing to the bench and let it go.  If the outboard wing does not drop when you let it go, add a little tip weight until it just barely moves.  Don't add so much that the Earth shakes when the outboard wing touches the work bench.  Make sure the elevators and flaps are 0-0 and completely free.  No binding at all!  Adjust the rudder and engine so that there is no offset in either one.

Print that out and follow it, and you will be sure to have a plane that is "bench trimmed".  As long as nothing has a huge warp, and everything is running well, the plane should fly well enough to move on to more advanced trimming.  I have basically memorized it over the years and hence I have no big surprises when I take off for the first test hop!  Most of the time I can fly a pattern on the first flight.

Of course, you can do whatever you want to do, it's you hobby, but I like to get on with flying and more advanced trimming.   We can always make a science project out of anything, but there are usually easier ways, more simple ways, to do things especially when you are starting out..

Big Bear

[john e. holliday]

Hey Bill, another great article was written by our own Ted Fancher for Stunt News back when he did the "DOCTOR".   Following his article on the "DOCTOR" build and trim helped me a lot.   

[Mike Anderson]

Thanks guys for the great advise, I tried running line III on my computer and it says its not compatible . My computer is running windows 7 and has a 64 bit operating system how can I get this program to work.Scott

This version is apparently even older than '32 bit' operating systems - don't know if anyone has recompiled it under 32 bit or later operating systems.  Here is an 'online' web version:

http://www.nclra.org/Programs/LineRake.php

You enter all your data and hit 'Calculate' - a box is presented with some calculations.  The one you are interested in is the "Line Sweep" calculation - that is the distance (in inches) from the CG rearward to the midpoint between  the lines.