: heli spinning on the spot, please help!



kenny81
21-07-2012, 02:39 PM
hey guys, im new to the world of rc helis & after a few cheaper helis i went out & brought myself a blade 450 3D not that i can fly well but u have to start somewhere right? i got a few ebooks explaining how to tame down the 450 to be a trainer but after a crash i put it all back together & when i went to take off about half throttle it spins round on the spot on the ground. i put a few notches on the trim on & then it spins the other way. i have since played with the tail servo trying to centre it etc etc, but to no avail. its still doing the same. i then set everything back to factory settings hoping this would fix it, but no. oh i have to mention to that it the tail servo has a bad twitch, its like its having a fit at times.
any suggestions would be greatly appreciated.

oh & does anyone know where i can go on the net to get terminology of words etc so i can understand what everything means?

Peter
21-07-2012, 04:40 PM
First thing to check is that the tail belt is installed correctly..
There's a 90 deg twist in the belt ; if you twist it the wrong way , you'll get the rotation thing that you have!

There's a few other possibilities too , but check that first...

Any heli clubs/flyers near you ?

I'll try to dig up a terminology page!!

Mick.
21-07-2012, 05:31 PM
Helifreaks is a good source for info:

Flight school:
http://www.helifreak.com/forumdisplay.php?f=242

And Finless Bob's Tech Room:
http://www.helifreak.com/forumdisplay.php?f=60&order=desc

Finless Bob does a range of Heli 101 setup videos which can be a great help.

little_drifter
21-07-2012, 08:46 PM
What gyro does it have?

kenny81
22-07-2012, 04:35 PM
a G210 by eflite

kenny81
22-07-2012, 04:39 PM
thanks peter i will try that once i fix it again, it broke the tail rotor grip/holder cos of the overload i think. if its not 1 thing its another! i dont really have a heli club here but i have heard of people that fly down the oval. im trying to find out more info of when they are down there so i can take it down & hopefully they can show me a thing or 2.

kenny81
22-07-2012, 04:40 PM
thanks mick i will have a look there

nzchopper
23-07-2012, 09:40 AM
My new heli build spun anti clockwise on start up, it gave me a hell of a fright..as soon as it got light on the skids, it must have spun at 100rpm or so.
I was not keen to test it again like that lol!

So, I strapped my trex500 to my old rx7 clutch pressure plate with the throwout bearing installed in the pressure plate...so the heli can spin around freely on the ground but not take off...

I then adjusted my gyro and tail blades to get it rite. Its interesting, the trex/gyro can stop the momentum of the heavy as rx7 clutch plate spinning!

im a complete noob, and cant really give any setup advise, but if you can strap it down to some kind of object so the heli can still spin around freely without taking off, then you can safely fix the issue without possibly loosing control of your heli and doing more damage.

best of luck to you

Mr.Leopard
23-07-2012, 02:43 PM
I wouldn't do that if you payed me, what happens if the heli untraps itself and comes at you at 150miles at hour with blades spinning at 2000 rpm? You got no time to run mate,

690 size blades spinning at 1800 rpm are doing 700 kmh an hour at the tip n will hit you at over 1 tonne of forcehttp://img.tapatalk.com/65771149-d694-549e.jpg

Look at what happens when 325mm blades hit you at 500 rpm

http://img.tapatalk.com/65771149-d678-5cdb.jpg

Mr.Leopard
23-07-2012, 02:45 PM
9 hours of micro surgery, 8 hole 1.5mm thick titanium ladder plate and 7 screws and 80 tendon damage...result is a finger that doesn't straighten or bend and is totally useless

Mick.
23-07-2012, 04:41 PM
Ouch! Very definitely need a healthy respect for safety.
Bet you don't do that again. Can you elaborate on exactly how you ended up like that?

Mr.Leopard
23-07-2012, 05:18 PM
Bench testing with blades on. Was checking for vibes, I was holding heli by the boom, mini titan v2

nzchopper
24-07-2012, 08:44 AM
thats a nasty injury indeed! certinly reinforces to be VERY careful!

I certinly wont be testing again without it securly attached to a bench, or in my case my old clutch pressure plate. I saw how scary that is!

I cabled tied heli to clutch plate with 4 x 30cm long, 6mm wide cable ties. No way was it doing anywhere. The clutch plate is heavy, probably 12-15kgs or so. (its out of my 300+hp rx7 so is heavy as it must take punishment.)
It works really well for me because it spins extremly smoothly, no chance of take off and you cant tip it over or anything if you tried.

I got my heli off the ground! and proceeded to crash it (ill make a new topic about that, also need info on some blades my mates wants to make for me on his CNC)

Mr.Leopard
24-07-2012, 09:00 AM
And wat makes you think the skids cannot break?

nzchopper
24-07-2012, 09:14 AM
you are correct, they most deffintly can.

what is the best procedure to safely bench test a heli then? how should one secure it?

I could also add a couple of large cable ties trough the actual frame?
thanks

Mr.Leopard
24-07-2012, 09:19 AM
Remove blades, main and tail, only thing you should be bench testing is checking for vibes and all other testing should be done while hovering

nzchopper
24-07-2012, 09:22 AM
ah ok yeah that makes sense, only reason I tied it down was because when i tried to hover it, spun around insanly fast as soon as it got lite on the skids, and i didnt want to try that again untill i had the issue sorted out.

I completly agree with you though, i could have done that without the main blades on.

Mr.Leopard
24-07-2012, 09:25 AM
Any gyro adjustments should be done in the air, usually with tail gyros, start at a high gain which the tail with wag n drop 5% at a time, that's what I do