big wobble

[stan]

When practicing my hovering to day with a raptor 30 with training aids (the ones with balls on the ends),I got what i can only describe as a big wobble .
This appeared to be the training aids but i am not shore.
I seem to remember reading some where of a similar story .
Can any one shed some light on this for me

[gazza]

Hi mate,

Have you had any light ( Or heavy ) crashes? Have you tipped the model over at any point?

Sounds like a small vibration is resonating through the training skids, the more the skid vibrates the more rebound energy the training skid ball will have.
It doesnt take much of an imbalance to cause this!

If you havent tipped the heli and bent anything then check the usual balanced items ie Blades & paddles

[Disc]

the Training aids even when secured correctly can start to shake and that then travels through the Heli making it worse. sit the Heli down and wind the head speed back... Wait then power her backup, nothing much you can do about it until you remove the training gear. Just make sure that the training aid properly secured. Also get off it as soon as you feel that you can.

[col9]

If nothing is bent/unbalanced on the heli to cause the wobble/vibration, cut a bit off the training gear rods legnth (an inch ish) this can be enough to stop it.

See ya
Col.

[jamiem]

i had this happen to me when i was first learning. i was hovering at about 10ft, maybe less, when one leg of the training under carriage started to wobble and resonate badly. i tried to drop it down to find the problem, but within a second or 2 (i had only just started to drop down), the leg that was vibrating worked its way loose of the centre pod that they all plug in to and it flew up in to the blades! as it happens all i did was kill the blades, as luckily it landed on it skids (albeit a little hard).

check that they are all pluged hard in to the plastic centre piece, posibbly glue them in if you can. as soon as you are confident enough, take them off!

[Stuart]

Also see this thread - searched the word vibration.

http://www.rcheliaddict.co.uk/showthread.php?t=1669

[Kwickkwack]

I had this problem on my raptor, Have you cut 100mm of the length of the training aid legs, this cured it for me, ironically I used the les on an old Baron30 first, caused no problems.

[canopycreations]

Kwickkwack done the correct remedy for this problem id recomend cutting off 1" of all the training legs at a time lift off into a hover with someone watching or even better flying her for you and check for any vibration going into the heli keep on cutting 1" at a time until she flys well i ended cutting 5" off mine when i first started just too cure the problem hope this helps

[Steve]

Or increase/reduce the head speed.

The harmonic oscilation has to start somewhere, and it's most likely to be head speed dependent. It's a bit like an out of balance front wheel on your car - wobbles like mad at 60mph, but goes smooth again at 70, or 50mph.

I always had a lot of airframe wobbles with my old Scuttle (RIP!) whenever the head speed crept above 1500 rpm. The answer was always to back it off a bit - even 50 rpm was enough.

[kingchopper]

the raptor 30 suffers from the raptor nod, combined with training aid, not surprised it wobbles.
up the head speed, to about 1800 and wobble should decrease, just experiment until the wobbles goes.
but a high speed isnt what you want if your just learning. so learn fast and loose the training aid.

[stan]

Thanks

Wow thanks for all the replies

I think I have found the problem, I recently changed the collective servo arm and didnt put it back in the right place.
When the stick was at 0 the blade pitch was at -4 so to get any lift meant i had a massive head speed, we will find out at the week end.