Vibrating

[patrickvdb]

Hello,

I have a new Thunder Tiger Raptor 50 V2.

a couple of questions:

1) Everything looks ok and it hovers perfectly, however sometimes during forward flight, the heli suddenly starts shaking violently. I can fly sometimes for 5 minutes without a problem and suddenly it starts.

I immediatly land the heli and its goes away instantly. then I can restart hoovering without a problem.

It suddenly appears without any specific reason that I can think of.

Any ideas?

2) when giving full throttle the tail does remain in position and goes a bit to the left. A have a futaba GY401 + Digital Servo on it.
What can I do to stop this?

Many thanks

[OHIOBOWHUNTER]

patrick , is it actually vibrating or is it the tail waging ?if its the tail waging you might have the gain set to high on the 401:). good luck

[patrickvdb]

No, it is not the tail wagging,
The whole heli starts to shake violently.
As soon as I land it, it goes away and I can start flying again.

thxs

[vera]

Well I donno but for openers I'd check the blade balance. The blades might weigh the same but that isn't good enough. The balance point (CG) for each blade has to be the same percent of the span. Find the balance point of both blades, individually, and check to see that they match. If not, you'll have to add some weight somewhere to get the balance points to match. Then you'll have to add more weight to one of those balance points to get the weight of the blades to match.

I'm thinking the CG may not be matched. Any change of blade loading during flight changes the coning angle somewhat and that changes the lead/lag. If the CGs don't match the lead/lag angle might become different, and that results in a offset CG for the whole rotor and vibration will result. It seems like this should straighten out on its own, and it would if the heli were to stay put. But by shaking it keeps changing the situation... kinda like a dog chasing its tail. When you put it on the ground the heli stays put and so the lead/lag can reach balance.

I might be full of gas but it wouldn't hurt to find the CG on both blades and check to see if they match. Apparently the blades balance as a pair or the heli would shake from the gitgo. Since that isn't your problem I'm guessing the CGs don't match.

[Pinecone]

Also check for loose links and loose balls. Check blade tightness.

You may be experiencing flutter, which can destroy things.

[Danyboy]

Hi there!

Have you got some means to measure headspeed?

I observed once that with a quite low headspeed, like 1200 instead of 1600. I got into some kind of resonance that would let the whole mechanics wave wildly like a pendulum under the rotor disc. Increasing headspeed to a more sensible value quickly led out of the situation.
For a Raptor50, I'd say at least 1600.

Also, check for loose links, loose balls or any other play. If that's the case, through the shaking it will get worse and worse and the longer the faster, eventually leading to a crash.

Cheers,

Daniel