T rex flying issues... and some solutions

[Tele]

Ok I dont know if everyone is having these problems but here are some issues that I have with the t Rex

1. ball links are very lose ..easy fixed the important ones simply plastic bag them ond put the links back on

2 .when flying the rex and you give ailerion movement I always got some elevator mixing problems ..ie going side to side the heli would crab back towards me as well or forward. this I think is an issue of loose linkages...I fixed most of the problem by converting all the linkages to ball links. The problems still was present but not as much ..so the rest i got rid of with some mixing on the TX. I have put some ailerion elevator mixing in +/- 10 on both ..and it looks to have done the trick. Now I can move from side to side quickly without any forward /back movement.

3. This problem I still am sourceing. I get a bad BOBBING happening with the heli in backward flight or even with a bit of wind on the side. i suspect that it could be the battery hangging so low underneath that it can be causing a pendulum effect and that could be the cause of it. has any one else had this issue. It couls also be the massive weightof the battery too causing this too compared with the rest of the weightof the heli.

thoughts opinions?

cheers doug

[Super-Hornet]

Hey doug

For mine... I think I only have ball linkage that is loose but so far it doesn't cause any problem.

I think for most of your problem, it is due to the Tower Power (SG-90) servo that u use. I saw and touch that servo yesterday and I can say "CANNOT MAKE IT LAH"!! It not only have huge free play, the gearing can move sideway as well.

Right now Rotor Hobby is offering HS-55 for just S$25. Use that Hitec instead. If money is not a problem or u want better quality a bit, go for HS-56 instead.

Super-Hornet

[Tele]

I already have some time ago (about two weeks ago )I have HS 56 BB all round and a gws naro for the tail ( working fine for now but will up grade later) so its not the servos.

I took them back and showed him the play in the servos and he agreed not good for heli! hhaha Now after I blown $60 on them but I will used them some where.

[Tele]

Ho yeah I have alos changed the screws for 2mm 10-12 mm hex bolts as they are a bit more accurate in there diameter and therefoe less slop. but you can see that

[X34]

Re: T rex flying issues... and some solutions

Originally posted by Tele


2 .when flying the rex and you give ailerion movement I always got some elevator mixing problems ..ie going side to side the heli would crab back towards me as well or forward. this I think is an issue of loose linkages...I fixed most of the problem by converting all the linkages to ball links. The problems still was present but not as much ..so the rest i got rid of with some mixing on the TX. I have put some ailerion elevator mixing in +/- 10 on both ..and it looks to have done the trick. Now I can move from side to side quickly without any forward /back movement.

thoughts opinions?

cheers doug

Hi Doug,

Sounds like your washout is not well aligned, to confirm this, you will also get ailerion movement when you input the elevator. If the washout is not adjustable, rotate it 180 deg may help.

Hope it helps.

James

[nic]

I got prob 2 too. However, the effect I got is not very consistent.. sometime have, sometime don't.

When I do a ground check.. I notice the swash plate sometimes will move, sometimes it doesn't... so that the intermittent I getting.

I haven't find any solution.... but I am getting used to giving it an manual correction with my elevator stick.

Going to try those suggestions mentioned above.

[Tele]

Re: Re: T rex flying issues... and some solutions

Originally posted by X34
Hi Doug,

Sounds like your washout is not well aligned, to confirm this, you will also get ailerion movement when you input the elevator. If the washout is not adjustable, rotate it 180 deg may help.

Hope it helps.

James

I am not too sure on how this will help ... the washout is fixed im place by two pins from the head mast and cant be moved...it looks exactly the same either way. I am not too sure that this will help..maybe you can explain some more.

Nic I adjusted the rate till I saw the swash not moving anymore..all it was is a slight movemene of the servo to stop the slop in the elevator linkages..but it looks to be working great ..smooth side to side now now forward and back

[X34]

Doug,

Maybe I was ahead of myself in the earlier post.

Assuming the swash plate is well setup, when u input elevator input, the swash plate rock front to back, no sideway rocking, aileron input - the swash plate rocks left right and no front back rocking. Input pitch it goes straight up and down. Check the elevator and aileron controls at low,middle and high pitch.

Check alignment of the following, reference point swash plate (SP)elevator ball link. SP to washout ball link align to elevator ball link. Is the flybar ball link in alignment?. It should be in a straight line. If all the points are not align, any input to the swash will cause secondary rotor movements. Since Trex washout guide pins are attached to the head mast. U can't adjust it and hopefully by rotating the washout by 180 deg it solve the problem.

Hope it is crystal.

James

[Tele]

clear thanks for that explaination james I get you now.

I think the probelm from what I can tell is that all the linkages are ok but the elevator arm had too much play so hence with ailerion input it moves slightly ..and when you are flying this bird with 50% dr already a small movement equates to a moving heli in the wrong direction.

PS for thoes that are going to copy what I have done with the mixing then its + 10 and +10 not -ve as I first stated.

this mixing moves the elevator arm ever so slightly but just enough to counter the aileron input basicly it takes the slop out out the elevator arm and holds it firm.

cheers

[Tele]

ok the bobbing is caused by too low head speed ..... increase the head speed and it should go away
lets see.

[X34]

Hmmmm, a chef in the making. Mixing away the unwanted smell with some flavor!

Anyway, "the slop in the elevator control" u think is design fault or just poor quality components. The elevator control system is similiar to the Raptor, Eagle etc.

By looking at your set up, your aileron linkage at the servo is in all the way, it may cause some binding at the 'L' lever.

cheers

[Tele]

no there is no binding there I have checked ..the issue is that the links that they have initaly made are too lose and they are making some new ones that will fix the problem also being that it is smaller then the standard raptor any small movements will equate to a larger movement then on a normal raptor.

doug

[X34]

Yup, I agree, a small movement on a small chopper makes a big difference.

Cheers

[X34]

I am assembling me Trex now.

Some stuff I discover could be the cause to your unwanted movement.

1, Ball links are different size some are 4.64mm and some are 4.74mm.

2, Swash plate ball links positions are not equal distance from centre. Off by as much as 0.5mm. Maybe rotate the swash plate by 90 deg. to find out which position is better.

3, When glue in washout guide pins, must make sure it is straight.



Cheers

[Tele]

I had suspected 2 as well and have tried to move the swash around a bit too no help though.