throttle return spring

[topher]

Evening

I read various posts about out of control helis with interest (and with deep sympathy for the owners!) so that I can try to ensure these things dont happen to my heli (although if it were to happen i wish it would go have a paddy on the car of the knob who drives past every evening shouting at me to call me a sad B****RD and telling me to get a real one) .

So I am going to go put some hot glue over my servo plugs now to stop those coming out with vibration but would like to put a throttle return spring as well.

Anyone got any pictures of such a set up so I can get some ideas?

Thanks

Chris

[Andy from Sandy]

First off you have to find a servo that when powered off is very easy to move. The best two that spring to mind are the Futaba 9254 and the JR 8900.

Just attach the spring to the carb end and stretch it to a position that pulls the throttle to the closed position. I can't help with a picture as I don't fly nitro. You have to be careful that when the carb is fully open the spring will be at its most stretched. It needs to not be over stretched nor too powerful that it will strain the servo unduly.

[Steve]

It's just a spring attached to the servo arm (outside of the actual ball position if possible) and to a fixed point on the frame which pulls the throttle arm back to stop in the event of a power failure. Needs to be strong enough to pull against a powerless servo but not too strong to make the servo struggle when in use. The spring could also be attached to the throttle arm if it's easier. It's worth considering what type of servo you use for the throttle if considering doing this as some are a lot easier to turn than others when unpowered.

In essence, that's about it.

[pgkevet]

..a rubber band can work too...

[Andy from Sandy]

Search RunRyder.

My throttle return spring. - Page 1 - RunRyder RC Helicopter

[murph]

Or you could correctly set the fail safe for loss of signal in your radio!

[Steve]

Or you could correctly set the fail safe for loss of signal in your radio!

Doesn't work if the heli looses power, like the battery pack falls out or something. This is a mechanical system that returns the throttle to idle or stop with no need for electrons.

[murph]

If that sounded sarcastic, it wasn't meant to be! But it is easy to set up the fail safe with Spektrum kit, and is easy to test with a nitro by simply turning off the radio when the rx is powered up. Not to be confused with an electric model, cos if you do it wrong on a leccy you could send it skywards!

[murph]

Doesn't work if the heli looses power, like the battery pack falls out or something. This is a mechanical system that returns the throttle to idle or stop with no need for electrons.

Ah ok that is different, I simply read it as losing control through signal loss, not a complete power loss. Make sure your battery is well secured then!!

[topher]

Gents

My fail safe is set correctly, throttle closes on loss of signal. I am glad a servo suggestion was made! i just tried a few springs and qucikly realised that i would need a fairly meaty spring to move my servo when it is power less (I have a futaba S3152 servos).

Anyway, I may be able to buy a new throttle servo as a 3152 just failed on my pitch control so I could use the throttle one on the pitch and buy a new throttle one! But thats a different story!

[DanWright]

I'm not trying to hijack the thread, but when you say glue the servo plugs, where do you apply the glue, and what do you glue it too?
After reading the other threads, I want to make my heli as safe as possible.

[Steve]

Gents

My fail safe is set correctly, throttle closes on loss of signal.

Yes that's great, but it still needs battery power to close after a loss of signal. If you are going full chat and loose power (not signal) then it will simply stay at full throttle until the inevitable happens. That's the point of the return spring - it returns the throttle to safe without any power.

Never used one myself, but there is a certain amount of sense and sensibility in the idea.

[Nick B]

be easier to make sure the battery is secure?

[Steve]

be easier to make sure the battery is secure?

Ok, let's assume the battery is bolted in with a couple of M10 nuts! What if the regulator dies, or a lead comes unplugged, or a soldered joint inside the pack splits or anything else that results in a total loss of power?

[moyesboy]

heres my return spring, coiled round the throttle shaft - hooks round the intake and round the control arm. There is no detectable loss of performance on the std spektrum servo. I used push pull so it is only torque on the servo and carb shaft not side load.

Works well.
It only just closes the throttle when all is static - I imagine it will close it quicker when there is engine vibration. I've not yet pulled the plug on my heli with it going full chat

I did this after my first ever funky chicken dance when it threw the lipo off after a nose impact.

- Just checked its a JR DS8231 not a spektrum servo.

return spring 1.jpgreturn spring.jpg


If there was enough interest I'd draw his up and get 50-100 made at a local spring manufacturer in macclesfield. Not sure if it would fit the 55 as well as the 50 hyper.