Model Forum / Radio Controlled / Helicopters / September 2006

I agree with your suggestions and all, but I'm about to diverge on a
tangent here :)

I've often wondered what it was that made my Blade CX so stable
compared to other helicopters.  I've been told that it's the
contra-rotating rotors, but that never seemed right, and after playing
with the $30 Picco-Z helicopter from Radio Shack I've realized what it
really is.

It's the stabilizer bar that makes the Blade CX (and Picco-Z) stable,
not the contra-rotating rotors.  If you twist the helicopter in some
direction, the gyroscopic effects on the stabilizer bar cause it to
adjust the pitch of the rotors it's connected to in such a way to
oppose the motion -- very elegant, simple and effective.

In the case of the Blade CX, the top rotor has the stabilizer bar
connected, so it's what keeps the helicopter stable, and the bottom
rotor has a swashplate connected, which is what allows you to control
the helicopter.  Having two rotors makes this practical (otherwise the
stabilizer bar and servos would fight) but is not what makes the
helicopter stable by itself, and you could certainly make a
contra-rotating helicopter without this stability.

Of course, this also means that when you push the stick all the way
somewhere, the two rotors are fighting each other.  The lower rotor
will eventually win, but since the two rotors are doing the opposite
thing, they're bending in opposite directions, and this tends to lead
to `blade clash'.  They really need to offer a mod where the distances
between the blades is increased -- either that, or more stiff blades.

(But as it is, the Blade CX is a great helicopter trainer.  But it
just doesn't work well outside -- the blades will collide, causing
damage and crashes.  Inside, it's great.  Outside, even light
winds/turbulence will cause this.)

Another advantage with the contra-rotating design is that tail
movements are minimized.  The cheap helicopters generally don't have
HH gyros, and while a rate gyro does help keep the tail motions
minimized, you still have to adjust for it.  But with contra-rotating
rotors, the tail tends to stay put, and the CX still has a gyro to
help control what little fluctuations are left.

Speaking of the Picco-Z, GREAT toy!  It's tiny, but just the thing for
putzing around the office.  Now, if they could make a new model that
had a HH gyro (I'm dreaming, I know) and a second tail rotor that's
pointed up/down (to give you pitch control) it could give the Blade CX
some serious competition in the area of a low-end/ helicopter trainer.
As it is now, it's a toy, but a fun toy.  You'll crash it often, but
it's so light, it never gets hurt.

(Sorry if I'm rambling here, or saying things that everybody already
knew.  It was just sort of an epiphany to me and I was sort of excited

"Ron van Sommeren" wrote>

"mporlier" wrote>

I guess some guys just have all the luck  ;o) just kidding. I am also a
bitch and a nagger.  ;o)

"Ron van Sommeren" wrote>

I didn't know this forum - thank you for telling me.
I guess I will need a simulator instead of a heli. When I saw a couple of
photos from first flights I could see the fun fading..........  :o/
Luckily he loves computergames - I know it isn't a "game" in that sense, but
you know what I mean.....
Does anyone have experience shopping here: http://www.hobbydirekt.de ? I
think I have visited the shop once - in my
'girlfriend-of-an-aircraft-spotter-days'.....(he dragged me from one
European airport to another)...  :o)

Thank you all so much for enlightening me on this very interesting subject!

Kind regards
Tanja