|Nov 13, 2003, 02:48 AM|
Joined Oct 2003
Need help setting up a CP picccolo as FP
Hello,Yes, its one more of those need help pleas!
I recently bought a CP piccolo with a MIA G10 frame,
PMP hi-speed alum head and other alum parts. The
tail motor is a high-authority motor. The main motor is
a hacker B20-36 S. I'm using a 9T pinion. The Gyro
is a GY240
Here are the threads in the classified section describing
For a start, I decided to set it up as an FP machine
just so I can stretch out my pleasure and have something
to look forward to!
I have pretty much finished building it and am in the
process of setting it up. I did set it up to a first degree
of approximation and got it to sort of hover for a few
seconds (altho the tail is swinging wildly) but I can tell I'm groping i the dark!
I have a whole bunch of questions in this regard but w
ill start with the basic ones.
o How should I decide the pitch of the blades? (I'm using
the stock piccolo wooden CP blades. I tried a few
settings and it seems like the pitch required to get the
machine to lift-off is pretty high. I havent measured it
but looks like 10-12 degrees. I presume I have to pick
a head speed and play with the pitch to get the heli
to hover at that rotor speed?
o Is there a simpler way to setting up the HH gyro than
what's described in the manual i.e. getting the machine
to hover in the non-HH mode first. The reason I ask is that
to get it to hover without HH on, I need to get the revo
mixing right first and this seems like quite a task in itself.
It would be nice to let the HH gyro take care of the tail directly
Also, whats a good source for instructions on how to
trim the heli?
|Nov 13, 2003, 04:24 AM|
From expereince I find using the CP blades for FP to be a bad idea.
You get the worst of both worlds: The instability of the CP blades at low rpm and the torque yaw from using the motor to adjust hight.
Get an FP rotorhead, blades, paddles and flybar. Then mount the CP flybar arms to make it fit the longer CP shaft.
Then you can change FP to CP in the snap of a rotorhead.
just an idea..
|Nov 13, 2003, 08:41 AM|
Joined May 2003
Set up Normal mode something like this. Throtlle curve if 5 point, 0,30,50,75,100 and run you pitch curve like this -3,inh,0,inh,10.
This will give you something close to start with, youll have to fiddle with the throttle curve around the 50 and 75 mark to get a hover a 3/4 hover. Mid stick you want to be 0 pitch, full down stick minus 1-3 degress. This is the way most learn on a nitro, it alows for low rpm flight and the ability to slam it to the ground with out a boom strike per say.
If you want it exaclty like a FP, set pitch to something like 6,6,6,6,6, then run the throttle curve linear like 0,25,50,75,100. You with have to play with the pitch untill you get 3/4 hover.
As far as the gyro set it to 80 percent and let it eat, adjust gain till it doesnt hunt or wag and keeps tail solid.
|Nov 13, 2003, 08:48 AM|
Joined May 2003
1 thing, make sure when playing with trhottle curves, make sure your curves match the desired rpm of the motor pinion combo. That is if 100 percent causes the motor to spin 4k rpm then you need to adjust the top curve to get it lower, then do the same thing for all the curves below it. so you may actually get a curve like 0,15,30,45,65. Just to keep head rpm 2000 or under.
Hope that made since.
|Nov 18, 2003, 04:32 PM|
Joined Oct 2003
Just got back to this folks. Thanks for all ur advice.
I'm set it up with a real fixed pitch just to experiment.
(Nick-P I;m going to use ur settings once i get my FP
version working. I'm more interested in learning about
helis than flying soon.)
So I have the blade pitch constant throughout the range
of throttle and am using throttle only for collective.
I have balanced the blades well (static. - made sure cg is
at the same spot) For dynamic I don't have a hi-point
balancer, Is this s necessity? I'm using the whole assembly
with the one way gear taken out as a balancer. The blades
stop horizontal at rest. The friction in this system isnt as low
as I'd like it to be so its slightly suspect.
I found one unexpected thing tho. I had to compensate for the
AR link on the head by adding a wheel collar on the flybar on
the other side. I can;t tell u what a big difference that made
for vibration when spun up without blades.
with blades, it spins up with very little vibration (subjective
based on my earlier experience with the Robin 300)
Now here's the problem. When I try to fly it, it picks
up nicely from the ground (1400 rpm or so) but once
it gets up in the air, it starts to wobble (like precession but
its fast) and becomes uncontrallable, I can't for the life of me
figure out why the heli would wobble. I've tried to set things
up rock solid with no play anywhere. Its possible the blades
are still not balanced correctly but then I shd feel it vibrate
when I hold the heli in my hand and spin it up. It does vibrate
but not much.
Is it possible that its because of what KasperE mentioned?
That the CP blades are fundamentally unstable at low rotor
speeds (is 1400 low?) I can play with the pitch some more
to see if I can increase rotor speed but I'm close to the point
where it wont lift off.
I'm using a 10 tooth pinion with 110T main gear and a 2400rpm/V hacker. I dont really know how to check if this
setup is correct or not.
Next experiment I plan to do is to replace the CP blades
with the plastic FP blades to see if the wobble goes away
but that involves modifying the blade mounting holes.
Still what I learnt so far about balancing blades is
well worth the pain I'm going thru. vs just setting up this
machine as CP as it was designed to be.
Any advice appreciated!
|Nov 18, 2003, 04:37 PM|
Joined Oct 2003
oh, one more thing. I did adjust tracking very carefully.
The PMP head assembly has screws to do this so it
wasnt too hard altho the screws are hard to reach.
|Nov 18, 2003, 05:54 PM|
First off, you don't need revo mixing with a heading hold gyro. Turning off your HH isn't a good idea. You should make sure that the tail holds steady once it lifts off the ground, if it wags, reduce the gain a little until it is steady at hover. 1400 RPM is way to slow for those blades. This would account for your wobbles your talking about. A CP Pro Piccolo should hover at around 1750 to 1800 RPM. Max RPM recommended by Ikirus is 2000! You need to get a Tac and check your head speed. You want it set so that it hovers steady at around 1750-1850 RPM. My guess is that your throttle will probably be around 45-48%. You can set your pitch curve all the same, say around 75% for starters. Like someone else said, you will have the worse of both worlds using your CP Pic as a FP. If you change the main shaft, blades, swash and control links I think you will probably have way to much head speed for a FP machine. As I remember the FP hovers around 1500 RPM, maybe even less! With your hacker motor and a 10 tooth gear, 110 main gear your getting and 11 to 1 ratio. 2400 Rpm per Volt would probably equate to somewhere around 2200 RPM at 100% throttle. Way to much for the FP!
I'd reconsider using the brushless motor on this setup and instead, if you can afford it, get the brushed motor, a Pixie-7P ESC for the main motor, and FP Blades and head. Once you learn to fly the FP then you can easily go back to the brushless Hacker, ESC and enjoy the best of both worlds!
I have both the FP and the CP Pro. Both have their merits, but I guess for just knocking around the backyard, the FP is the best since it's just about impossible to damage it, baring running into the brick wall or the ground at full tilt!
Hope this helps!
|Nov 18, 2003, 08:03 PM|
Joined Oct 2003
I turned off the HH just to get feel for the "basic" FP
configuration. However, that is one more wrench
in the works so I will turn it on.
I will try to raise the hover rpm to 1750.
I understand what you are saying about 100% throttle being too
fast. However all I care about for a start is getting this
thing to hover. that shouldnt be any different for an FP
or CP machine,- more or less const pitch and const rpm.
As far as switching to a brushed, I'm not sure why I need to.
Wouldn't just playing with my ATV setting to set the max
throttle speed work? I guess the hacker is heavier so
from that point of view, i shd probably switch to a brushed.
I have a graupner s300 and a pixie-7 lying around. I;ll
give that a shot too.
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