Iam haveing trouble with my rascal 40 arf, iam running a OS .52
fs, 11+6 prop, standard 4 channel setup, the plane takes off
straight but when i get airborne and make my turn out
the plane gets hard to control... rolls to the left then when i trim
it for level flight, it goes the other way...then it will fly perfect for a few seconds.. then it starts the squirrely crap again..
I checked and rechecked the balance, range checked my radio
with the engine running and off, double checked all the connections, everything i can think to check. and it still does
it, iam scared to fly it now because i came real close to loseing it
today, i also checked my control surface throws and they are right on the money... i just cant figure out what is going wrong here, when i fly my super sport 4 it tracks and flys like its on a rail...! any ideas ? thanks.... BH

Your having a lot of trouble with this plane! First the trim is way off, now its hard to fly! Is it to sensitive? You said it was set up with the correct throws, but maybe they're not right for you. Other than that, I don't know much about this subject. I haven't had this kind of a problem, yet.

What radio are you using? If it is a computer radio, you should have Exponential. Dial in some to soften the controls, maybe 30%.
Or if no computer, try dual rates.

I think you just have too much throw.. Try the above. Good Luck

Seems obvious, but make sure the wing is very securely attatched to the fuselage. I don't know if this airplane uses rubber bands or nylon bolts to secure the wing in place, but if they are not tight enough the wing can seperate slightly from the fuselage in flight, and this can give you a wild ride for no apparent reason.

Two things, first make sure your ailerons are parallel to the airplane's thrust line at neutral, as "drooping" ailerons can cause some wierd trim problems, especially if combined with slight tail heaviness. Also closely check your aileron servo to make sure it returns to center. I had an aileron servo that would go several degrees "over center" every time I let off the stick, and I fought the trim for several flights and couldn't get it right. After changing the servo, all was well.

Also, make sure your engine doesn't have any upthrust in it, this can also give you some funky charicteristics and make trimming a nightmare.

OK, plane is balanced where it's supposed to be, but acts like it's not balanced where it's supposed to be...

Have you checked your incidences (i.e. the angle of the wing and tail plane)? The incidence angles and balance point work together and although people don't usually talk about incidence (because it's locked in), if youre wing is at the wrong angle the effect will be the same as if the CG is off. For a plane that acts unstable as though the CG were too far back, raise the leading edge a click at a time and you may see some big improvements.

I don't think this is a loose wing problem because your description sounds like it's happening during what should be straight flight, so no particular force change to make the wing pop up and cause this. I also don't think it will be fixed by reducing your throws (either mechanically or through exponential or low rate settings), again because it sounds like it's happening when you're not giving the plane input.

I'll be interested to hear more as you tweak the plane in... let us know what does the job once you get the problem fixed.

b,

Sounds like everyone here is right on. Do all that stuff, then if your're scared to fly it, when you go back to the club get an experienced flyer to look at it. Explain what its doing. Maybe have him stand out next to you on the pad while you fly. They'll figure it out

You know, those guys that sit around the picnic table telling war stories

1. Check CG, start out slightly nose heavy

2. Make sure you dont have to much throw, if computer add some expo to ailerons and elevator and put on low rates.

3. do radio check again

Good luck!

yes as above..make slightly nose heavy and be sure yur elev control rods in fuse aren't flexing. does it do this at slow speeds too? -Tinman-

Thanks guys , iam gonna track down someone at the club with
an incidence meter. Plus let an expetienced flyer take her up and
see what the the deal is. Keep sending me ideas to check in the meantime...BH

Just a thought as everyone said be sure the balance is right but have you checked the latteral balance as this being off would cause the flying characteristics that you describe

Taz,

Just wandering .. , describe to us how to check lateral balance, I've always wanted to know

Thanks, nine.

Try holding your control surfaces while you turn the servos to see if there is some play or a servo with stripped gears. Use some care not to break anything. Also make sure everything is tight and there are no loose parts or holes in the covering.

One of those experts, get them to fly it for you. Be nice to have someone to blame in case disaster strikes :-)

The way I was tought is hold both ends of the prop only dont hold the fuse and have someone else hold the tailsection with one finger under the fuse at the very back of the plane if it is properly balanced it should remain flat if the latteral balance is off in either direction the plane will have one wing dip down depending on witch side is heaviest .If it is off it does make for some ugly flying hope thisw helps .have fun and keepem flying

The above is the correct proceedure, but you want to lift the plane several times and see which way it tilts. If it tilts the same way each time, add a few weights to the wingtip (the side that keeps going up). Repeat this proceedure until the plane either stays level, or tilts in either direction. Then, permenently attach the weights.

I like to use something like "Split Shots" as weights, then when it balances, remove 1 or 2 (depending on their size), put a small hole in the wing, forward of the spar where the wing is sheeted (and therefore encased in balsa) and then drop in the weights with a little CA or epoxy to hold them in place. guesstimate the amount of epoxy to be about the same weight as the weight of the splitshots you removed. Then apply covering over the hole.

Lateral balancing is a 1 man job. All you need is a table. I use my freezer. Have the nose of the plane pointing toward you and let the tailwheel sit on the back end of the table. Hold the plane by the spinner and one wing. Level the plane and slowly release the wing. Watch to see if the plane tilts to the left or right. Have the plane over the table so that if the plane tilts badly the wingtip that falls will be caught by the table. If the balance is off, then place a small weight over a rib of the wingtip that went up. The farther out you are toward the outside, the less weight you will need to balance. Reccheck the balance and adjust the weight as needed. When you get it balanced, then secure the weight. I like to cut a small hole in the covering at the bottom of the wing beside the rib, glue the weight onto the rib and recover. Recheck your balance after. Good lateral balance isn't all that noticable at higher speeds but really shows up when at slower speeds especially when you are slowing down to land! Have fun, Fast!

Check to see if there is any warp in one, or both, wings, tail, rudder. It sounds like you are able to trim it initially, but airspeed changes are producing more or less lift in one direction. The same concept as a plane rolling faster when it's going faster.

Just a thought.
Jet

Thanks for the input, i did check all that, i tried to sit down and think out exzactly how it flew, it all happened so quick, but i do remember that when i took off, then made my turnout,
to the left the plane went knife edge and i i had to pulll in a lot of elevator to make the turn, i also discovered by makeing a homemade balanceing stand that the plane is tail heavy,
i thought i had it balance but i stand corrected on that , so iam
goin to add the weight to the nose , about 3 oz. and see what happenes, does this sound like a tail heavy characteristic?
Thanks B

DUUUUUUUUUUUUHHHHHHHHHH Yea.

Can you remember if it was pitch sensitive? From what I've heard, the first sign of a tail heavy plane is sensitive elevator.

There's an old expression... The guy who invented the arrow was the first aeronautical engineer.

Think of a dart... heavy nose, feathers on the tail. even if thrown poorly, the point usually hits first. If a plane gets tail heavy, basically what happens is that the tail wants to lead the way.

A nose heavy plane will always keep the nose out front, but it will be sluggish, have a high stall speed, and therefore it will land very fast. The more tail heavy a plane is, the more manuverable. BUT theres a fine line between manuverability and UNCONTROLLABLE!

Personally, I think one of the fine arts of this hobby is balancing a plane correctly, both front to back, and laterally.

Laterally is usually the easier of the two, because you can see it. You want the plane to balance in the center. But front to back is a trial and error thing. Move the CG around in small increments and see how the plane responds. When it flys the way YOU want it to fly, that's where the balance point should be.