Add nose weight or slow down the control

Finally after 1 year and 3 months of building, finishing, getting frustrated, sanding and re-finishing I put the first two flights on the Legacy yesterday. Did the complete pattern on the second flight and overall it flew really well. I have a few trim issues to work out but nothing major (I don't think).

First issue... It groves in level flight better than anything I have ever flown and glides excellent. However it doesn't want to track in the rounds and I really have to watch the amount of control I give it in a square or I bobble the corners. The controls seem really sensitive even though I set it up with a 4 inch bellcrank and long Tom Morris control horns. I did have my handle spacing at the widest setting thinking that was the safest setting for a new ship. Just wondering if I should be looking at narrowing the handle spacing, adding nose weight or something else I haven't thought of? Ideas?????

LAST EDITED ON Jan-13-04 AT 01:18 PM (CDT)
 
Bob,

Great paint job, except that engine fire's gonna’ scorch it.

LAST EDITED ON Jan-13-04 AT 01:01 PM (CDT)
 
Hi Bob,

Great looking airplane. I'm sure it's going to turn out just fine after a bit of trimming work.

I think you've likely pegged the problem. I don't know what handle you are using but the widest setting on most any of them will likely make modern stuff respond pretty briskly. Your description of the glide would indicate that it isn't particularly tail heavy which takes that out of the equation.

The modern designs like the legacy have very large and powerful tails in proportion to the wing. As a result, acceptable CG locations can be much further aft without sacrificing stability. This is a good thing.

The combination of the powerful tail and aft CGs does result in an airplane which requires much less control for a given rate of pitch change. As a result, excessive handle spacing will produce the symptoms you describe ... apparently stable but too quick in response; almost like it's tail heavy.

I think your first response should be to narrow the handle spacing. If, for instance, it is now four inches or more, take a pretty good whack at it. move both lines in about a quarter inch ... you want to move it enough that the difference will be significant enough to verify the results.

Try it at that setting but DO NOT do the wingover first trick out of the box. Do a combination of rounds and squares and a figure eight or two to get a feel for the change. If you've gone too far you'll be able to easily react to the slower rate without jeopardizing your pretty airplane. If this improves things make modest changes to fine tune the feel to your liking.

Just a quick refresher. With a modern design you can pretty much comfortably set the CG at 25% aft of the leading edge at the average chord (technically we should talk about the mean chord but with a straight modestly tapered wing the average is plenty close enough). Check your Legacy and if the CG is in this ball park or forward and even if a tiny bit aft you are almost certainly looking at a control rate issue rather than CG.

Good luck. Let us know about your progress.

a friend of mine has a Cardinal, a similar design plane with a large tail. Through various tests we flew it with a variation of as much as 3 ounces in nose weight and it made little difference in how tight it would turn and only a modest change in how "touchy" it was. Does sound like you have to much handle spacing.

Thanks guys, this is my first step out of classic 35 size 4-2-4 stunt ships and am really excited about flying a somewhat modern airplane. The cg is just a smidgen forward of the 25% average cord point so I will play with handle spacing next time out.

The problem this time of year is having a somewhat warm day with light winds when I can get to the field. It may be spring before I get it trimmed well enough to fly in a contest.

Appreciate the input..
Bob

hey it looks good i like the flames. will we see it at brodak this year? what motor did you say you used?

I sure hope you see it at Brodaks along with the Skylark 46 still on the work bench. Going to have to tear down my shop in the next week or two to get ready for the big move so may not get the Skylark finished.

It's powered with a Stalker .61 RE, 3 blade carbon fiber 13 - 5 1/4 prop (thanks to Igor Burger), runs 8 min on 6 ounces of 5 - 22 Powermaster. Solid run at 5.6 to 5.7 second laps on 64 foot lines.

hey wish i was ther eto help you move it will be worth it just think you will have your own flying circle in your yard thats got to be cool.