Conference vmszoo::rc

    A couple of things come to mind. 
    
    1. Gyro sensitivity too high. This is a clasic cause of tail wagging.
       Maybe the gyro is broke in now and is more efficient than when
       you first flew with it. Or maybe head speed has increased. That
       means the tail rotor's going fast also which means it has more thrust.
       Try turning the gyro down  and see if the tail settles down.
    
    2. Something in the drive train is seizing/slipping. This could
       be something like the tail drive belt slipping or the swashplate
       bearing heating up and intermittently seizing. The end result
       is that the gyro is fighting massive changes in torque and not
       quite keeping up. Check the belt adjustments. Then pop the pushrods
       off of the servos that control the swashplate/head and make sure
       they move with no binding. 
    
    3. The gyro itself may be broke. 
    
    3. The gyro could be broke. 

 .1 #1 - Gyro gain too high, seems the likliest cause.

>    2.  The G-152 gyro.  This guy is more complex than my simple GMP
>    	gyro as it has a "neutral adjust" as well as two additional 
>     	adjustment knobs located on the ON/OFF switch box.  I NEVER
>    	CHANGED THESE FROM THEIR FACTORY SETTINGS.

    I use a 152 gryo on my Concept and have had no real problems. I don't 
mean to sound flipant, but have you RTFM? The two adjustment knobs on the 
switch panel are the gain adjustments for the two diferent rates. I can't 
tell you what mine are set at off the top of my head but I'll have a look 
tonight. You should have a lead from the gyro to the "Gear" channel on the 
receiver (if you have one) which allows you to switch between the two rates 
while in flight (or if you're as green as I am - land first, flick the switch 
and try again!). It could be that you're second flight was using the higher 
rate. I would try setting one to about 40-50% and the other to about 70% and 
see what happens when you change over.

 Good luck,

  Ken.

    why turning knobs if it worked befor?
    if something is different from one flight to another,you either
    misaligned something on your tx,or one part of the chopper is breaking,
    most likely a servo,which works with the engine turned off,but working
    unstable with a running engine.
    i hope you find the cause soon
    regards,
    hermann mueller,dsc munich
    

    I had a quick check of my settings which are perhaps a bit on the high 
side :- No.1 is set at about 80-85% and No.2 is at about 60%.

    I find that in _very_ calm conditions No.1 keeps a nice steady hover, but 
if the wind gets up (or if I dare to enter forward flight) the weather-cocking 
effects tend to start it hunting a bit so I switch to No.2. The only time I 
had real trouble with the tail (totally unflyable) was when I accidentally 
connected the tail blades back-to-front after a minor dunt had popped off the 
two pitch control ball joints (took us ages to figure out what was wrong!).

    One other remote possibility (if the hunting is realy severe i.e. 
uncontrolable) is that the gyro is in the wrong sense, thereby exagerating 
any movements, but this is unlikly as the switch is not easily got at at the 
best of times, never mind by accident (worth checking all the same).

Hope you get things sorted out,

Happy langings,

Ken.

P.S. I am _not_, by any stretch of the imagination, an expert so feel free to
totally ignore me! If I can put back 0.0~01% of the help I've got from this
notes file I'll be happy.

    It's my understanding that the Concept has a tailwire driven
    rear rotor. Check for a worn spot on the main gear. Or it
    could be something as simple as an engine adjustment for the
    daily conditions. If the engine is set a little rich and the
    humidity changes then the RPM May fluctuate creating torque
    differences.
    
    
    					Tom

    Thanks for all the good suggestions!  I think I found the problem:
    Doing some preflight tightening down, I found that the rudder servo
    had loosened up quite a bit.  I'll bet that the whole unit was 
    moving in response to any input signal, so only a portion of the 
    motion was getting to the tail.
    
    I think it loosened up because I couldn't get the screws in from the
    bottom per the instructions, so I put them in from the top using the
    little brass "bushings" they tell you not to use!  I think that results
    in a "spongier" mount, and is more subject to loosening.
    
    RE: the gyro rate adjustments, I set them to about 50% each and it
    seems to fly well (i.e. hover well) now.  One thing I don't understand
    though; since I don't have an extra channel to switch between gyro
    rates, am I running on no.1 or no. 2?
    
    Thanks again for your suggestions!
    
    /Rick

    I am using a 153 gyro and the instructions for using it with out
    a spare channel are:
    
    	adjust the output with control box trimmere (1) and (2).
    
    	When trimmer (1) is 0, the output can be adjusted from 0 to
        50% with trimmer (2).
    
    	When trimmer (1) is 100%, the output can be adjusted from 50%
    	to 100% with trimmer (2).


           <<< HYDRA::DISK_NOTES$LIBRARY:[000000]DAVE_BARRY.NOTE;1 >>>
                           Dave Barry - Noted humorist 

From: [email protected] (Dave Barry)
Subject: THE RULES OF HELICOPTER PILOTING, ACCORDING TO DAVE BARRY
Date: Sat, 17 Apr 93 19:08:02 PDT

DAVE BARRY
	TODAY'S AVIATION TOPIC IS: How to fly a helicopter. Although flying a
helicopter may seem very difficult, the truth is that if you can drive a
car, you can, with just a few minutes of instruction, take the controls
of one of these amazing machines. Of course you would immediately crash
and die. This is why you need to remember:
	RULE ONE OF HELICOPTER PILOTING: Always have somebody sitting right
next to you who actually knows how to fly the helicopter and can snatch
the controls away from you.
	Because the truth is that helicopters are nothing at all like cars.
Cars work because of basic scientific principles that everybody
understands, such as internal combustion and parallel parking. Whereas
scientists still have no idea what holds helicopters up. ``Whatever it
is, it could stop at any moment,'' is their current feeling. This leads
us to:
	RULE TWO OF HELICOPTER PILOTING: Maybe you should forget the entire
thing.
	This was what I was thinking on a recent Saturday morning as I stood
outside a small airport in South Florida, where I was about to take my
first helicopter lesson. This was not my idea. This was the idea of Pam
Gallina-Raissiguier, a pilot who flies radio reporters over Miami during
rush hour so they can alert drivers to traffic problems (``Bob, we have
a three-mile backup on the interstate due to an overturned cocaine
truck'').
	Pam is active in an international organization of women helicopter
pilots called -- Gloria Steinem, avert your eyes -- the ``Whirly Girls.''
She thought it would be a great idea for me to take a helicopter lesson.
	I began having severe doubts when I saw Pam's helicopter. This was a
small helicopter. It looked like it should have a little slot where you
insert quarters to make it go up and down. I knew that if we got
airborne in a helicopter this size in South Florida, some of our larger
tropical flying insects could very well attempt to mate with us.
	Also, this helicopter had no doors. As a Frequent Flyer, I know for a
fact that all your leading U.S. airlines, despite being bankrupt,
maintain a strict safety policy of having doors on their aircraft.
	``Don't we need a larger helicopter?'' I asked Pam. ``With doors?''
	``Get in,'' said Pam.
	You don't defy a direct order from a Whirly Girl.
	Now we're in the helicopter, and Pam is explaining the controls to me
over the headset, but there's static and the engine is making a lot of
noise.
	``... your throttle (something),'' she is saying. ``This is your
cyclic and (something) your collective.''
	``What?'' I say.
	``(something) give you the controls when we reach 500 feet,'' Pam
says.
	``WHAT?'' I say.
	But Pam is not listening. She is moving a control thing and WHOOAAA
we are off the ground, hovering, and now WHOOOOAAAAAA we are shooting up
in the air, and there are still no doors on this particular helicopter.
	Now Pam is giving me the main control thing.
	RULE THREE OF HELICOPTER PILOTING: If anybody tries to give you the
main control thing, refuse to take it.
	Pam says: ``You don't need hardly any pressure to ...''
	AIEEEEEEEEEEEEEE
	``That was too much pressure,'' Pam says.
	Now I am flying the helicopter. I AM FLYING THE HELICOPTER. I am
flying it by not moving a single body part, for fear of jiggling the
control thing. I look like the Lincoln Memorial statue of Abraham
Lincoln, only more rigid.
	``Make a right turn,'' Pam is saying.
	I gingerly move the control thing one zillionth of an inch to the
right and the helicopter LEANS OVER TOWARD MY SIDE AND THERE IS STILL NO
DOOR HERE. I instantly move the thing one zillionth of an inch back.
	``I'm not turning right,'' I inform Pam.
	``What?'' she says.
	``Only left turns,'' I tell her. When you've been flying helicopters
as long as I have, you know your limits.
	After a while it becomes clear to Pam that if she continues to allow
the Lincoln statue to pilot the helicopter, we are going to wind up
flying in a straight line until we run out of fuel, possibly over
Antarctica, so she takes the control thing back. That is the good news.
The bad news is, she's now saying something about demonstrating an
``emergency procedure.''
	``It's for when your engine dies,'' Pam says. ``It's called `auto-
rotation.' Do you like amusement park rides?''
	I say: ``No, I DOOOOOOOOOOOOO ...''
	RULE FOUR OF HELICOPTER PILOTING: ``Auto-rotation'' means ``coming
down out of the sky at about the same speed and aerodynamic stability as
that of a forklift dropped from a bomber.''
	Now we're close to the ground (although my stomach is still at 500
feet), and Pam is completing my training by having me hover the
helicopter.
	RULE FIVE OF HELICOPTER PILOTING: You can't hover the helicopter. The
idea is to hang over one spot on the ground. I am hovering over an area
approximately the size of Australia. I am swooping around sideways and
backward like a crazed bumblebee. If I were trying to rescue a person
from the roof of a 100-story burning building, the person would realize
that it would be safer to simply jump. At times I think I am hovering
upside-down. Even Pam looks nervous.
	So I am very happy when we finally get back to the ground.
Pam tells me I did great, and she'd be glad to take me up again.  I
tell her that sounds like a fun idea.

	RULE SIX OF HELICOPTER PILOTING:  Sometimes you have to lie.