Reducing Head Speed

[Talisa]

How do you go about reducing the head speed of a heli. Why does a reduction in head speed make the heli more sluggish control wise. Somebody was trying to explain it to me (something to do with pitch I think) but I got lost after the first sentence.

Anybody care to enlighten me?

Regards,

[Ade_Law]

you reduce the throttle in the throttle curve.

when the blade is moving faster through the air it will generate more lift at the same pitch angle, this includes the cyclics so when the headspeed it produces less lift on the left side than the right so rotates slower.

as with anything heli there are some gyroscopic forces in there too :-)

Ade

[GhostlyRock]

Its never simple is it.

[scallybert]

you reduce the throttle in the throttle curve.

Isn't there more to it than this ?

If you're going to maintain the same lift at reduced head speed, you'll need to increase the collective pitch.

This may mean your motor needs to produce more torque - and if it's electric, draw more current. Since this is a limiting factor for ESC, motor and battery, this may cause problems.

If so, you'll need to reduce the gearing (ie make motor run faster).

There's a lot of 'if's and 'maybe's in that, but my (limited) experience is that significantly reducing the head speed takes the motor over current, unless you reduce the gearing.

To make things worse, the throttle setting doesn't necessarilly directly relate to engine revs. Depending on how your ESC is designed and configured.

It all seems like a sparsely documented black art.

[Ade_Law]

ahh sorry should have looked at the models in his signature.

by slowing the head down you will need to use slightly more pitch to create the same amount of lift, you will do this with your fingers, leave the pitch curve linear.

if your decreasing the headspeed alot then yes you are better to change the pinion to decrease the gearing rather than dropping the throttle right down. If you get much under 85% throttle then you will start to loose efficiency.

Ade

[Talisa]

Thank you to all for your descriptions/explanations. Kind of understand where you are all coming from.

Hopefully giong to fly my new 600CF today (reduced head speed). Certainly going to spin it up (with my training carriage obviously). Very nervous about it though.

Regards,

[andylinney]

Talisa, if you've had it set up by an experienced person already I'd be inclined to leave the throttle and pitch curves well enough alone. If you're wanting less sensitive controls then consider putting some exponential on your aileron and elevator channels. This will make these controls less sensitive around the middle stick (where you're going to be spending most of your time while you're learning) yet keeps all of the major settings intact. You don't mention which radio you're using but for me about 35% expo works a treat.

[Tim Procter]

Hopefully giong to fly my new 600CF today (reduced head speed).

Is there any reason in particular you are reducing the head speed..

They fly much better at optimum speed, Not reduced.

[andylinney]

Buster - he's wanting to take advantage of the reduced sensitivity of the slower head. Hence the reason I suggested using expo instead.

[Tim Procter]

Ah... Cheers Andy.

[Ade_Law]

thats a good question andy, has the model been checked over by somebody experienced and test flown?

if not i strongly suggest you do.

if it has been checked over and test flown i recomend you leave it as it was setup by them.

Ade

[Talisa]

It has been setup for me by a very experienced pilot and i certainly have no intention of changing a thing. I was merely trying to understand the concept of how it works.

Regards,