Pitch & Throttle Curvs

[Steve Rogers]

Hey guys just got my 50 going Sun & have something I just dont get.
Heres what I got - I have 12 deg pitch on top 11 1/2 on bottom my stick is set up to be 0 deg @ 1/2 & 50% throttle. 100% +/- ATV on pitch, 90% +/- ATV on throttle. The thing is if I leave everything linear my head speed is cranking over 2000 at 1/2 stick (0 pitch & 50% throttle). I've counted the gears & I have the 10/85 tooth gears for the fifty (Ghobee) . Is this normal? (First 50 machine so go easy on me ). IF I leave the pitch curv linear I have to get down to around 60% on the throttle to keep the head speed below 1850 which means I bearly get out of the mid range of the engine & have no real torq or good climb out. I can tweek both curvs to keep a good steady 1800 but I have to add so much pitch barly past center (9Z) that it takes very little movement of the stick to go from hover to drop like a rock! In other words make a smooth transition.
Is this what I'll have to deal with to keep the engine in its high band for power & a safe head speed or am I missing something???

Thanks In Advance!
Steve

[BarracudaHockey]

11.5 is probably a bit much for a 50, try +- 10

[Steve Rogers]

Not in this case. If I dont put the pitch that high & put a big sag in the throttle curve the head speed is outrageous. Even still at full throttle climb out (12 deg) my head speed picks up from around 1800 to 1850 & pulls out like a rocket!

[ClayK]

It was 12 degrees with a gauge at full positive collective?

[Steve Rogers]

Yep.
My curvs are as follows on a 9Z starting @ 1/2 stick 0 pitch 50% throttle on the carb

Pitch - 50 66 78 87 95 98 100

Throttle - 44 52 58 65 73 83 95

If I go to 100 % on the throttle at the top I gain quiet a bit of headspeed during a long climb out. About 65 gives me a good head speed of around 1700 but since the motor is barley above the mid range I dont get into the power band & performance is a little slugish not to mention the high speed needle has no affect.

I've set up a couple of helis now & had problems with bogging but never to much!

Either I've got one hell of a motor or I'm doing something wrong?????

[Bayou Talker]

If you set your pitch curve linear with +-10 or 11, then you will be hovering at about 3/4 stick. Adjust your throttle curves to obtain the desired head speed for each flight mode (normal, idle 1, idle 2) at hover. That may well be less than 50% at mid-stick especially if you are using a Hyper 50. Then increase the throttle curve as you go up to full stick to maintain the same head speed. In normal mode, adjust the throttle curve below that point to get a smooth transition for landing. You might also want to limit negative pitch in normal to -5 degrees and positive to +10 or 11.

If you want a better throttle response. try a governor. That way head speed is always where you want it just don't forget to set curves also in the event the governor is not functioning properly.

[BarracudaHockey]

Are you using a wheel on the collective servo? Something tells me you aren't actually getting 12 degrees of pitch under load or you have some very efficent blades.

[Steve Rogers]

Not using a wheel but rather a heavy duty arm & running the Gohbee 600 carbons. The pitch guage (actually 2 different ones) say 12 at full stick & climb out is rocket like. I dont think I'd get that with anything less than 10.

I know it just dosent sound right but not only have I checked myself more than once but 2 others have checked it out as well.

Gots me :dontknow

[ClayK]

Trim end points to bring in that 12 degrees. Adjust throttle curve to keep headspeed to target RPM in hover, per Bayou. Tach the headspeed under load, if you can, during climb out and adjust throttle curve accordingly.

Do you have the balls on the pitch servo arm on the outside of the arm or closer to the center?

[Steve Rogers]

There on the outside & close in on the carb arm. From reading Rays set up book when I set my first heli up this was recomended to keep the throttle alittle ahead of the collective. Due to my situation I've been thinking of doing just the opposite to a point. The Gohbee manual gives the distance from center of the servo to the ball & thats what I followed?

[BarracudaHockey]

Dont sweat the throttle leading the collective thing. What everyone that writes about that fails to take into account is the fact that there's virtually zero load on the throttle servo and a fairly significant load on the collective servo, so even if they are the same the throttle is still going to get there first.

[Bayou Talker]

Set the throttle curve to 0% on the bottom and 100% on the top and ATV for throttle is 100%. Then make sure the carb is going from full open to full closed with full stick movement. If it is, the link is the correct length and set the correct distance from the center of each arm. If it is either too much travel or too little, then move the balls in or out until you get them as close as possible to the correct travel. Small adjustments can then be made with the curve to achieve the correct travel. After that, set the curves to achieve the correct head speed.

The same technique can be used on all of the servo links. I find it works better to get as close as possible mechanically to full throws first and then to fine tune with ATV or curves to achieve the travel you need.