Twister Medevac stability problems.

[cwilding]

Hi All,

First post after lots of reading and viewing. I got a Medevac for Christmas, took it nice and slowly and got pretty decent with it (all relative I guess). Obviously as a newbie I crashed and burned a few times but I have only had to replace the tail section and a "few" blades.

However now it seems to have gone haywire. I trim and retrim but nothing seems to change the following characteristics. The copter takes off OK but as soon as it is up there it starts lurching around all over the place, not in any set direction but almost seems to pivot on the shaft between the blades, in other words it seems almost to swing around like it is drunk - and it is totally uncontrollable.

Has anyone any ideas what has happened, and how I go about rectifying this.

Many Thanks,

[jboweruk]

Okay, first off, check the flybar isn't bent on top of the blades, if not the next step is track the blades, make sure they look as one when at eye level and running at speed. If they aren't then you will need to adjust the flybar linkage until they do.

If this won't/can't work and you are getting a wobble on the shaft, then the next step is the shaft's themselves. Make sure they are straight. I know from bitter experience any one of these can cause nightmares. If it's a combination of 2 or more it can be a real pain to cure, so check them all in sequence.

[cambs flyer]

That sounds like a bent inner or outer shaft, I'd replace both if I was you.

When you say she lurches all of a sudden when up has always been my tale tale sign of bent shafts.

Ground her until there replaced or you possibly do more damage.

[andylinney]

could be a seperated swash plate too, the medivacs are famous for it and do lurch around when the swash pops out of the bearing. See if it'll click back into place...

[David Drew]

Hi All,

..........lurching around all over the place, not in any set direction but almost seems to pivot on the shaft between the blades, in other words it seems almost to swing around like it is drunk - and it is totally uncontrollable.

Has anyone any ideas what has happened, and how I go about rectifying this.

Many Thanks,

Have a few cans & learn to lurch the opposite way & then everything will seem back to normal, you have a good time, heli flying is great and you'll save all that money for spare parts

Or.....take the really, more boring, sensible advice in the other posts

Stella anyone???

David