This is bad why?

On Tue, 20 Jun 2006 23:03:43 -0400, Galen Hekhuis
<ghekhuis@earthlink.net> wrote:
> Don't most autogyros change pitch and roll by actually changing the angle
> of the hub of the main rotor? In other words, doesn't the axis of rotation
> of the blades of the main rotor change relative to the aircraft body in an
> autogyro?

That is correct... The stick controls the angle of the rotor disc with
respect to the rest of the aircraft... Push forward and the rotor disc
is more horizontal, pull back and it catches more of the relative
wind... Same type of behavior with left and right... Of particular
note is that it is considered a bad thing to unload the rotor
blades... Relative wind coming through the top of the rotor disc will
slow down the blades and that is a *very* bad thing... It is quite
possible for you to find out fairly quickly how bad gravity can really
suck... PIOs can significantly compound this problem... When a rotor
blade hits the rudder, your day is going to be *really* bad...

The blades change in pitch as they rotate, but it is from flexing of
the blades, not any sort of mechanical linkage...

With a gyro, it is possible to land in a smaller area than my Grumman
could even think about landing and if everything is done correctly, it
will not be damaged... This is good since quite frankly, you don't get
much time to pick your landing spot... If I lose an engine in my
Grumman, I have quite a bit more time to look for a landing spot, but
spots that won't damage the aircraft might not be readily available...
The gyro was fun, but not practical... Kind of like a motorcycle -- a
slow motorcycle at that...

On Wed, 21 Jun 2006 04:41:55 GMT, Grumman-581
<grumman581@DIE-SPAMMER-SCUM-gmail.com> wrote:

>That is correct... The stick controls the angle of the rotor disc with
>respect to the rest of the aircraft... Push forward and the rotor disc
>is more horizontal, pull back and it catches more of the relative
>wind... Same type of behavior with left and right...

That's pretty much the way I thought helicopters worked, until I started
reading up on them. It isn't. As you push forward on the stick (cyclic)
the blade facing forward generates less lift than the blade in back, as the
thing rotates, the pitch is changed on the rear blade so as it comes
forward it generates less lift, and as the once forward blade rotates to
the rear its pitch is also changed (opposite the change of the one now in
front) so that it generates more lift. Resulting in a nose-down situation
of the aircraft causing forward motion. Altering the pitch of a specific
blade during its rotation seemed a bit like magic to me, or at least
something that would require some sort of computer control. But no, this
is all accomplished by the swash plate of the helicopter, a rather complex
but elegant purely mechanical device. The collective control operates much
more like a variable pitch prop, in that it varies the pitch of all the
blades the same amount throughout the entire rotation.

>Of particular
>note is that it is considered a bad thing to unload the rotor
>blades... Relative wind coming through the top of the rotor disc will
>slow down the blades and that is a *very* bad thing... It is quite
>possible for you to find out fairly quickly how bad gravity can really
>suck... PIOs can significantly compound this problem... When a rotor
>blade hits the rudder, your day is going to be *really* bad...
>
>The blades change in pitch as they rotate, but it is from flexing of
>the blades, not any sort of mechanical linkage...

Helicopter blades flex too, although they are also modified via mechanical
linkage.

>With a gyro, it is possible to land in a smaller area than my Grumman
>could even think about landing and if everything is done correctly, it
>will not be damaged... This is good since quite frankly, you don't get
>much time to pick your landing spot... If I lose an engine in my
>Grumman, I have quite a bit more time to look for a landing spot, but
>spots that won't damage the aircraft might not be readily available...
>The gyro was fun, but not practical... Kind of like a motorcycle -- a
>slow motorcycle at that...

From what I've read, it is quite possible to land an autogyro in less space
than it is able to take off in. In other words, an area large enough for
landing may not have sufficient room for an autogyro to take off. But that
aside, a helicopter does not fly like an autogyro, either with power or
with a loss of power. A "dead stick" helicopter does not behave like a
"dead stick" autogyro.

Galen Hekhuis NpD, JFR, GWA ghekhuis@earthlink.net
Hell hath no fury like a bird in the hand.

On Wed, 21 Jun 2006 16:49:38 -0400, Galen Hekhuis
<ghekhuis@earthlink.net> wrote:
> From what I've read, it is quite possible to land an autogyro in less space
> than it is able to take off in. In other words, an area large enough for
> landing may not have sufficient room for an autogyro to take off.

That is definitely the case... There are some prerotator jump systems,
but they basicaly just get rid of the ground roll... Mine had a
prerotator, but it just reduced the need for much of the ground roll
that is necessary to get the blades up to speed... If you don't get
them up to speed before the takeoff roll, there's a chance of them
ocillating and hitting the rudder or the prop... Definitely a bad
thing...

> But that aside, a helicopter does not fly like an autogyro,
> either with power or with a loss of power. A "dead stick"
> helicopter does not behave like a "dead stick" autogyro.

Other than the fact that they are both going down -- rather quickly...
And, if you don't do it right, you are going to have a somewhat
expensive piece of scrap metal on your hands -- assuming you are still
alive...

Gravit sucks ... and then you die ...