Phil May Posted January 20, 2013 Share Posted January 20, 2013 Hi all. As I have mentioned elsewhere, I have bought a really cheap 2nd hand 3 channel model to use at the local farmers field ( and work ) I tried it out yesterday and found that it was very 'lazy' when trying to turn ( it's rudder only ) It just did not really want to turn much at all. Rudder throw was 1/2 " I am not really sure what the model is, but it is 36" span with approx 5 degrees dihedral and weighs approx 500g. It has a 380 brushed can which surprisingly pulled it around reasonably well... I do not know what the C of G is meant to be so I have started at 25% of the wing chord, but at this it appeared to drag it's butt around. Any ideas or advice guys. Cheers Phil Edited By Big Phil on 20/01/2013 13:15:03 Quote Link to comment Share on other sites More sharing options...
WolstonFlyer Posted January 20, 2013 Share Posted January 20, 2013 Hi PhilTo start with, if it was my model I would increase the rudder throw quite a bit (perhaps even as much as it will alow) but I would also have a dual rate setup to switch back again to a lower rate if needed in a hurry!I would also try adding some nose weight/bigger battery if it was dragging it's tail. Also check the elevator trim. Quote Link to comment Share on other sites More sharing options...
Peter Beeney Posted January 20, 2013 Share Posted January 20, 2013 Sounds just like a typical small 3 channel model to me, Phil. One of the reasons I forsook 3 ch for 4 ch, for teaching purposes anyway, a lifetime ago. But some of these can also be quite good fun. I had to seriously eat my words once, when I told a beginner that his 3 channel trainer might be a bit unsuitable, but it had been designed and kitted by a skilled aeromodeller. Tailor it to your needs, what I would do is to increase all throws to the very maximum, if still not enough increase the size of the rudder; it will probably get a bit lively, but with practice predictable. Especially as you say it has good performance to start with, in my book that’s always a fairly necessary requirement. One of the problems I always have with three channels is steering on the ground for take-off, and even if I remind myself, I always forget, at least for the first take-off of a new model; I also use the rudder a great deal in the air, too, and so that also causes some momentary confusion…… Good Luck. PB Quote Link to comment Share on other sites More sharing options...
LMA Dave Posted January 20, 2013 Share Posted January 20, 2013 Hi Phil, I have to agree with Wolston Flyer on this one, it does sound a bit tail heavy to me, I use to have a ME109 on three channel I had hours of fun with it, I am sorry I let it go. Quote Link to comment Share on other sites More sharing options...
Phil May Posted January 20, 2013 Author Share Posted January 20, 2013 Thanks guys. I'll add a little nose weight and max out the throws on the rudder and go from there. Phil Quote Link to comment Share on other sites More sharing options...
crispin church Posted January 20, 2013 Share Posted January 20, 2013 before adding weight look to see if you can move battery nearer the front Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted January 20, 2013 Share Posted January 20, 2013 hello big phil...happy new year...dont eat the yellow snow and all that....... try more movement and maybe if you can or want to....increase the size of the rudder slightly........more movement will prob do the trick..... ken anderson ne..1 ...more movement dept... Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted January 20, 2013 Share Posted January 20, 2013 BigPhil That's not an awful lot of dihedral is it ?.If all else fails ,you might have to increase it .Having tried turning with rudder only on my piper cub , which has little dihedral also ,it's almost impossible and just yaws .Then again they are notorious for not being suitable for training purposes with aileron reversal probs if differential is not incorporated in substantial amounts IMHO. Good luck- Myron Quote Link to comment Share on other sites More sharing options...
Terry Whiting 1 Posted January 20, 2013 Share Posted January 20, 2013 Hi Phil. Balancing @ 25% chord with a slight nose DOWN sit would be a good start. From your description of draging it's butt would suggest to me it is still lail heavy, If possible move the battery forward by at least 1/2",. also increase the rudder area and give that a try before increasing the throws mechanically. Best of luck. Terry Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted January 20, 2013 Share Posted January 20, 2013 I think Myron may have a good point here. Five degrees is not a lot of dihedral for a rudder only model. If increasing the throw doesn't help I think a "wedgie" between the wing halves is the next place to look! BEB Quote Link to comment Share on other sites More sharing options...
PatMc Posted January 20, 2013 Share Posted January 20, 2013 I agree with SDF. The turn rate could probably be increased by simply moving the cg back in small increments & re-trimming with a little down elevator until it will fly hands off S&L. Quote Link to comment Share on other sites More sharing options...
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