Thread: What would you do? 2nd Hand Heli

at centre stick the servo horn should be horizontal and 90degrees tp the push rod

thanks steve. shall have a look at her after the footy

Originally Posted by rhysduk

Thanks very much guys, I thought it would need a head set-up (oh joy - i remember the pain of doing my 450!).

So with the 250 servo's and centering, do the servo's get centred and then either;
1.) the servo arms attached parallel to the heli fuselage/body/airframe
2.) servo arms attached parallel with the servo body.
I ask this because the two cyclic(?)(front two) servos on the 250 are mounted at an angle to the lower airframe IE; not parallel to the air frame like my 450

Parallel with skids or main gear.

Originally Posted by AcidDrink

Parallel with servo body.

No the arm should be horizontal, not parallel with the servo

if the horn is parallel with the servo you will have less linear movement upwards than you will downwards so your swash movement will be uneven

a servo only has so much linear movement before it converts to rotation, and most of its linear movement occurs straight away, when the servo enters rotation you will loose linear movement until the point where the servo is just rotating and not providing any linear movement
this is why Expo is used - but thats a whole new lesson !!

in order to make sure you have equal movement upwards and downwards on the servo the horn needs to be at 90 degrees to the arm when at centre stick, the servo mounting angle has no bearing on the mechanical setup of the linkage

some helis have horizontal servos, some have vertical servos and some have servos at an angle, but all have the horn horizontal and at 90 degrees to the linkage

see attached photo, note the horn is horizontal and offset from the servo

Yes, apologies for misleading, parallel to the skids, or main gear. Pictured a wrong heli in my head

Thanks very much for that explanation Steve!
Much clearer now...

Can anyone point me in the direction of a Futaba RX heli channel list?

I give up with this f******g thing. I offically HATE setting up heli's.
Now one of the servo's seems to have died.
Bloody hell!!!!!!!!!!!!!

Edit: drown my sorrows in whiskey. why not.

Originally Posted by rhysduk

Thanks very much for that explanation Steve!
Much clearer now...

Can anyone point me in the direction of a Futaba RX heli channel list?

1 - aileron
2 - elevator
3 - throttle
4 - rudder
5 - gyro
6 - pitch

Steve,
I cannot for the life of me get my elevator servo centred at half stick!
Any ideas? The servo's teeth just dont seem to allow for the correct setup.... I need approx -50 of up trim (max) or -100 of subtrim to get it horizontal to the push rod.

Untitled by rhys_rdpstudios, on Flickr