Hi. I have a new Raptor 60 and a 601 Gyro. Gyro is set to Normal mode for now, and
here's the problem.

When I fire it up, it wants to spin counter-clockwise. (Yaw left). If I apply maximum
right rudder the tail rotor pitch goes to maximum, and the heli does not rotate left,
nor does it turn right. I can apply less than max right rudder and it will slightly want
to turn... or no right rudder and it really spins.

I've got the Gyro set to Normal mode (not avcs mode) for testing, and i can see that
the blad pitch is REALLY at maximum on the tail rotor... and yet... the heli still wants
to spin.

Any ideas how to correct this? I have a feeling I did "something wrong" but can't
figure out what... since at full RPM I figure the tail rotor should be pushing the boom
left (and hence making the heli yaw right or spin clockwise).

Thanks in advance.

Ehud

first make sure gyro dosent to be reversed,and then for the first flight test set the gyro in hh and give that a try,now as for the spinning you may have the linkages way off and that could be why its spinning like you say.

Gyro is correct. Docs say if nose goes right servo should spin left - it does.
(Tried reversing anyway... made problem much worse, that's not it.)

Not sure how to set linkages different... right now servo 75% right
has rudder pitch ALL THE WAY set. At that point it *still* doesn't generate
enough force to yaw to the right (clockwise). NO matter what I do, and
we're talking linkage all the way so pitch is maxed... it will stay straight,
will not yaw right.

MOre thoughts apreciated... I can test stuff out all day long... hope to get it working :&gt
Thanks!

E

well heres what i would do is go thru the whole gyro set up from start to finish,check to that there is enough travel set in the radio and in the gyro.

*nod* Maybe I'm not understanding... but here's what I see as the problem.

When the rudder stick is all the way right, the servo is all the way (left I think)
and at that point the rudder pitch IS maxed out. There's no more movement in
the linkages. At that point the actual thrust is insufficient to move the rotor left.
There's enough to prevent the rotor from moving right or left.

If there's some subtle lessening of the pitch that the gyro is doing, that's possible,
but I've gone through the setup, and it's all at default values (xcept the A and B
endpoints).

What would you suggest I look at and set? Mechanically it OUGHT to be ok. I suppose
I could set the linkage for max right rudder and see if it spins clockwise and then I'll
KNOW it's a gyro problem... but any advice prior to that would be helpful.

Again, thanks. Anything helps

Ehud

Do you have the center of your servo travel set to neutral pitch on the tail rotor? If so, you will have the problem you describe. The center of servo travel should be set to apply right thrust on the tail. The heli will naturally want to turn to the left, and the center of the tail rotor travel should be set to just cancel this.

I have a 601 in my Fury.

You might try setting the gyro in the linkage limit mode, this would take the gyro out of the loop and give you direct control of the servo. Then try to hover, if you have proper tail authority the problem is in the gyro set up. If the problem is still there it is linkage, or maybe the tail rotor blades are to small? It is not easy to hover this way, but you can get a quick idea of where the problem is. 20 years ago I taught my self to fly helis with out a gyro or even tail rotor mixing, not as much fun but it can be done.

I had a slightly simular problem with mine, I could get great control to the left, but sluggesh to the right. I just did not have the set up right. Works great now.

Steven

If I understand you right, you say you can move the tail rotor to max neg and pos pitch with the servo & linkage, but while your running, you don't get enough thrust to rotate clockwise... just enough to stop the couterclockwise torque rotation...

If that is correct, then I'd guess that:
1) You're not getting enough engine RPMs to make the tail rotor effective enough to overcome the torque rotation.
2) Something's wrong with your tail rotor blades... installed backwards, too small, etc.
3) Somethings wrong with your tail-rotor drive train... belt slipping, etc.

If all that checks out, here's a remote possibility...

I've read that if the tail rotor rotates down with the downwash of the main blades, you can sometimes have an ineffective tail-rotor thrust (due to the decreased "lift" on that tail blade). It's better to have the tail rotor rotate up into the downwash of the main blades (increases the "lift" on that tail blade). By reversing the blades, belt and servo control, it seems you could swap between these two modes of operation, for better or worse, (this also changes it from pusher to a puller tail rotor, or vice versa). I believe it's possible for your kit to be designed with the tail rotor rotating up into the downwash, yet reverse things the right way during assembly to make it rotate down, decreasing the tail rotor effectiveness... not real likely, but possible, I think!

You understand my situation correctly.

I'll try reversing and see if it makes a difference -- thanks!

E

Reversing the blades made no appreciable difference, helping to convince
me that the speed is too low.

I then bumped up the speed to 80% throttle (problem here, see below)
and at that point right rudder indeed caused a little yaw to the left.

I've got my rotor blade pitched mixed with throttle such that from
50% throttle to 100% throttle it goes from 0deg pitch to 12deg pitch.
I suspect that may be too agressive, as I'm taking off before I have
full rudder control.

What do you guys use for a throttle/blade pitch mix line/curve?

Thanks

Ehud

Ehud: are a few things you need to do

1- take out all tail mixing from the radio.
2- make sure you have equal travel for your throttle from low to high ( ATV's set to 80% low and 80% high, this is just an example)
3- set your throttle curve to 0%, 25%, 50%, 75%, 100%
4- make sure you have equal travel in the tail servo from left to right in ATV's
5- leading edge of the top tail blades when vertical should be facing the rear of the heli and the tail rotor turns CCW
6- mechanically max out the servo travel so that the pitch arm hits the tail rotor and the tail gear case.
7- set your gyro to heading hold
8- keep your gyro gain under 37% in the gyro
9- pitch curve set to low -2 degrees, hovering +5 degrees, top end +9 degrees
10- if you can check the main rotor rpm's during hovering adjust your high end needle on the motor to get 1600 rpm's

if none of this helps you may have a problem with the tail drive, it maybe slipping.



Good luck

Alan......

Alan, thanks, will try that over the next few days.

What ratio do you use to mix your throttle and rotor pitch.
In other words, for -2deg would that be at 50%, 75%, ? throttle.
I assume 9deg is at max throttle... and 5 is somewhere in between?

E

Where do you want the throttle stick to be in the hover?

If you want it to be half way up then this needs to correspond to hover pitch and throttle. This will be about 5 degrees pitch and 50% throttle.

In this case start with the following:

MAIN BLADE PITCH

Pitch curve: -2 degrees pitch at bottom, 5 degrees at middle (Hover) and 9 degrees at top
Throttle curve: 0% at bottom, 50% at middle and 100% at top

Any other points filled in to give you straight(ish) lines on your curves.

HOWEVER, for a beginner I might think about setting the bottom to 0 degrees pitch initially. This will soften the pitch response slightly.

ROTOR BLADE PITCH


If you are trying to hover at half stick then here is you problem. As I stated in another post you will need some pitch on the blade to prevent the torque reaction from spinning the model in the hover. If your Raptor blades spin clockwise when viewed from the top (they should) and the tail rotor blades spin the right way round then the trailind edge (back part) of the lower blade should point very slightly to the right to prevent constant spinning. The best way of setting this up is to ensure that at the tail rotor end, the pushrod is at 90 degrees to the part of the tail pitch control lever that it is connected to. This will give you a rough starting point.

If you want to hover at 3/4 stick (there are reasons for doing this) then the curves are different.

It is hard for me to explain this but I can tell that your heli is not set up correctly. Go to www.raptortechnique.com and have a look. This will explain the setup process. I'm not sure if he uses a Raptor 60 but the process (and most of the figures) will be the same for a beginner.

Hope this helps

I just wanted to pipe in and say thanks. The stuff at raptortechnique.com has kept
me busy re-configuring all day and will likely take two more days until I'm satisfied

THanks for the tip!

Ehud

Ehud,


I had to set my throttle/tail rotor pitch mixing a little at a time. I also had the same problem with my tail rotor not having enough thrust, and I found the gear that drives the tail rotor was stripped (X-cell pro). I could actuall see the tail rotor blades decrease in rpm when I applied left or right rudder.


Good luck