psuguru

I had to remove the pilot figure and move the servos forward to get mine to balance. Even then I had 4 oz of lead on the engine bearers. OS 120AX engine with alloy spinner.
Having 3 servos in the tail is just too much unless you have a 50cc petrol engine and big batteries up front.
Flies nicely though.

Anton9040

I have more than 14oz to put in but if on tube center it’s will be 6-8oz

and engine I have use is DLE35 RA 2 batt. 2 cell live 3000 and one ignition 2000 . And tail it’s heavy I think because of the high weight of servos . But I can’t move them . One for throttle is in the front and 2 batt. for servos on side of f.tank . In the end we have today check C&G ang put about 300 grams to get C&G on the center of tube . What’s it’s means I have with this 300 g weight my C&G is 3cm / 1inch back original what they are recomend in manual.

im apologize for my English not so good
thanks

psuguru

Typical airfoil (aerofoil) sections are unstable in flight. They require a stabiliser (tailplane, horizontal stabiliser). For this to work properly, the centre of gravity of the plane has to be within a range of distances. Too far forward and the plane will fly with up elevator all the time and will land very quickly. Too far aft and the aircraft will be very sensitive to pitch (elevator) control or even be unstable.
You say you "can't move" the rear servo's. What you actually mean is that to move the servo's you would have to modify the kit.
The first thing I would do is get rid of the pilot figure. This is worth about 100g in the nose.
Put the engine servo, ignition system and battery in the engine bay.
Try to get the receiver battery in the engine bay.
Use an alloy spinner.
Instead of having nose weight as useless lead, try building up the inside of the nose area with flexible plywood (1mm). I found the original wood was so flimsy I would crack it just by picking up the model.
If you still need nose weight, move the rudder servo forward and connect to the rudder using push-pull cables. 100g moved from the tail is worth 400g added to the nose.
There used to be heavy weight spinner inserts that put a weight very far forward.
Any weight you add should be as far forward as you can manage. If it is attached to the engine or engine bearers, it damps vibration in the fuselage.