I got my trainer off the ground yesterday and it was tail heavy so it was a hand full to fly. I put some more weight in the front and today it flew better. I still have a problem though, it randomly likes to pitch up, like a dolphin.

I have the CG about 3- 3.5 inches from the front of the wing and cant figure out what it is. Coming out of turns it is the same finish turning and boom up it goes. The only thing i can narrow it down to is a tiny bit of slop in the elevator, ( not much) checked the ailerons, same bit of play. I highly doubt you could get it out at all.

I bought the plane second hand, its a frontier 40. any help or experiece with these????

You didn't say anything about the transmitter...is it new as well? perhaps there is some kind of mix in it...
have you ever done a range check with the motor running to see if you get an elevator deflection after the ailerons?
lastly make sure your not adding throttle in your turns as a flat bottomed wing will want to climb with power on.....

transmitter is a dx7 and is all fine. No mix. A little throttle....... maybe thats the problem, but its only about 10% throttle?

Even just flying in a straight line it just jumps up sometimes......

G'day Mate,
When you come out of a turn, release the elevator first, then level the wings, with a trainer, it may still zoom a bit, but will be less of a problem, if done this way, instead of level wings first then release elevator.
Do you fly mode 1 or 2?
I asked because it's easier to release the elevator, then level with ailerons, when using mode 1.

Not sure of your experience level, but if these are your first flights, congratulations on not totalling the plane.

Most beginners experience "pitching" of the plane because they don't have a feel for the plane. They may be accidentally putting pressure on the elevator when applying ailerons. Coming out of turns this is particularly evident for a couple reasons. First, they tend to let the nose drop during the turn. This causes a slight dive, and an increase in air speed. Since the trainer is designed to climb with speed, when you come out of the turn faster than you entered, the plane will climb. Secondly, holding the elevator after trying to level the wings is also very common, which results in the same behavior.

I can't count the number of times students have said to me "I don't know why its trying to climb". I tell them level the plane and then release the sticks completely. They're always amazed that the plane continues flying straight and level with no input.

Now if your plane "just jumps" with no input, that could be either turbulence (what were the weather conditions) or a bad receiver or transmitter. If they're new, send them back to be checked out. If they're used, send them back to be checked out, even if it costs a few dollars.

Finally, and most obviously, get somebody with experience to fly the plane for you and see what they say. There are a host of other mechanical or electrical problems you could be experiencing. Nicked servo wires, stripped servo gears, wing incidence, stabilizer incidence, and so on.

Brad

range check? do you have a metal clevis on a metal throttle arm?

from the manual the ideal cg is 90mm from l.e or 3.54inches

Congrats on getting into the hobby. With some quality insruction, you'll have your airplane doing exactly what you want soon.
One thing you mentioned is that you added nose weight to bring the CG forward. You shouldn't add weight to adjust the CG if you can do it another way. Moving your battery forward is a common way to handle a CG problem, and some flyers go so far as to move the reciever too. Good luck on learning. Do you have an instructor yet?

IS the wing held by rubber bands? If so, you might want to add a few more. Sometimes the wing can lift at the leading edge and cause a pitch up

The slop in the elevator is not the problem.
The tail is pushing down; hence, any slop will become a down deflection of the elevator.

The CG is correctly located, for now.

I also suspect of the rubber bands and the wing incidence, since the problem happens erratically.

Do you have an experienced pilot that can fly it for you?

Good call about the elastics.

The plane will not perform the way you want it to, especially if you're the "Bank-n-Yank" kind of pilot.

Fly your flights smoothly and at half power once at cruise... it better for the airframe.

Hi!
Sudden jumps upward is usually due to too few rubber bands as the leading edge of the wing lifts! You should use at least six!

Definitely check the rubber bands, I had to same thing happen to me.
Make sure to use enough of them, and you should also use brand new ones every time you fly.

hi use 8 rubber bands on each side and 4 criss cross to hold the 8 on-that will eliminate any possibility of wing lift-even under high G stress stunts-good luck-enjoy this great hobby

HI check to see that your engine is at zero degrees to your stab-or increases and decreases from engine power (rpms) will cause the plane to rise and fall in flight-put another way no down or up built into the engine mount-engine s/b pulling straight foward

Yes, use more rubber bands and don't use much elevator in the turns.

Trainers (at least mine) are far more prone to turbulence problems on a windy day, just correct them and it will fly fine (if the wing is properly secured).

Also, I hate asking, but are you using the trim?

ok thank you to everyone for their responses. I have taken everything into account and sounds like i need mroe rubber bands. I am only using 4 and thought the wings still have a bit of movement.
I will add 4 more and test her then.

I only flew it for the first time on saturday then on sunday. I have been flying helis and thought i would give a plane a go. So far so good, yeh didnt crash her touch wood! Sunday i got dead stick and think she came down better with no power haha

I will be taking it to the local club sunday to let them check her out, but for now im going to add mroe rubber band and practise letting go of the elevator more then get the wings flat.

Dam i have to wait all week now!

oh and yeh it was a bit windy on saturday... although sunday was an improvement with the wind and the CG

Don't use less than 10 to 12 #64 rubber bands.
Wash them after each flight day.
Don't use them more than a few times, since the Sun and the fuel and oil make them weaker quick.

ok... not 100% sure what #64 rubber bands are, not sure what size my ones are at the moment.

Another question while i have everyones atention, how much throw do i need on the elevator, aileron and rudder? i have the ds821 servos on 85% travel adjustment each way at the moment

Check this manual, page 11 for the recommended throws:

http://www.theworldmodels.com/para/i...ion/html/A046/

Check this other link for the dimensions of #64 rubber bands:

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXYR49

You dont have to have #64 rubber bands. I have never used those and I've never had any problems. You can buy a bag for like 85 cents, I usually get mine a walmart. I use 12 bands, 4 on each side and then 4 crossing

You might try checking the throws on your control surfaces. i.e. Elevators, Ailerons and Rudder. They should be set at 1/2" for up and down for Elevator, 3/8' up and down for Ailerons and 1" left and right for Rudder.

I used to keep my rubber bands in a container of baking soda after flying, this neutralizes the oils and preserves the rubberbands. I used mine for a whole season and never had even one break when i was on my trainer. It is a good precaution to occasionally replace them tho.

The rule of thumb on rubber bands is one NEW rubber band on each side for every pound of airplane. I always just crisscrossed the last one and never had a problem with them slipping off. I also reused them quite a bit, tossing the ones that were starting to crack and throwing a few extra on when they started getting weaker.