Gentlemen,
I would be happy to clear a dispute from Australia.
First a quote of a post by Birdy
(forget the spelling, read it to the end, please):
I am going to stick my head on the block with this one.
To Mitch,Paul,Tom, Dick and Harry,to an extent i agree with you on H.stabs.
But,and a big BUT,i don't beleave they stabelise in all conditions!!!
If you close your eyes and imagine a machine flying in strong,even gusty HORISONTAL winds it is easy to see the stab would have a canceling efect on drag variations on the airframe in horisontal gusts.
Now throw in some extreme virtical gusts,on a windy or still day and my minds eye can clearly see how the stab WILL pitch the matchine.
A 2500 fpm up draught=around 50kmh,up.So if you are cruising at 60-70kmh,it is a severe chang in AOA on the airfame,including the stab.[such up draughts and stronger are comone in arid oz,winter or summer.]A strong up draught has miniscule afecte on a machines pitch with no
stab,sure the horisontal gusts do pitch it a bit,but no way near as much as the virticle ones with a stab fitted.I know which ones i would rarther contend with.
PLEASE,close your eyes and try to see were i am coming from befor you shoot me down in flames,remember,i am a simple cow grower,i confuse easly with long winded explenations and technical jargon.[dont worry,i'm not a front verander pilot ether,i can see it in my minds eye and feel it in my cheeks up there]
I feel better now.
For me Birdy is right !
On a fixed wing such an up wind-shear changes the AoA dramatically and leads to immediate stall, so the HS function to pitch the craft down immediately decreases the AoA and prevents stall.
BUT: 1. Gyro cannot stall, this dramatic change of the rotor AoA means noting, just
more lift !
2. The change of gyro pitch does NOT change the rotor AoA, (if the stick is not
fixed to the dashboard...) like on the fixed wing.
So the only effect is swinging the cabin under the rotor !!!
What I am scared of, is that in an extreme case a long, tall tail can hit the blades !!!!
The centrifugal forces on the rotor will keep it flat, and the tail will be pushed
up against the baldes. PLEASE, correct me if I am wrong !
Of course this is a case described by Birdy, big HS on a gyro with no cabin.
Then the vertical Center of Drag from below is far behind the CoG and
we have high pitching moment.
If the area of the cabin and HS, as seen from below, are symmetric against the
CoG than there is no problem.
So, maybe not HS, CLT but the "harmony" as described by Mr. Magni and Greg Gremminger is what counts.
Big, long cabin (tandem) has to be balanced with big, long HS.
Short, no cabin gyro needs no HS.
For short, no cabin gyro long, big HS is DEADLY in an up wind-shear.
I know, nobody here has the cash to do wind tunel tests,
but maybe there is an objective way to settle this dispute
in a civilized way.
Please.
PTKay
I would be happy to clear a dispute from Australia.
First a quote of a post by Birdy
(forget the spelling, read it to the end, please):
I am going to stick my head on the block with this one.
To Mitch,Paul,Tom, Dick and Harry,to an extent i agree with you on H.stabs.
But,and a big BUT,i don't beleave they stabelise in all conditions!!!
If you close your eyes and imagine a machine flying in strong,even gusty HORISONTAL winds it is easy to see the stab would have a canceling efect on drag variations on the airframe in horisontal gusts.
Now throw in some extreme virtical gusts,on a windy or still day and my minds eye can clearly see how the stab WILL pitch the matchine.
A 2500 fpm up draught=around 50kmh,up.So if you are cruising at 60-70kmh,it is a severe chang in AOA on the airfame,including the stab.[such up draughts and stronger are comone in arid oz,winter or summer.]A strong up draught has miniscule afecte on a machines pitch with no
stab,sure the horisontal gusts do pitch it a bit,but no way near as much as the virticle ones with a stab fitted.I know which ones i would rarther contend with.
PLEASE,close your eyes and try to see were i am coming from befor you shoot me down in flames,remember,i am a simple cow grower,i confuse easly with long winded explenations and technical jargon.[dont worry,i'm not a front verander pilot ether,i can see it in my minds eye and feel it in my cheeks up there]
I feel better now.
For me Birdy is right !
On a fixed wing such an up wind-shear changes the AoA dramatically and leads to immediate stall, so the HS function to pitch the craft down immediately decreases the AoA and prevents stall.
BUT: 1. Gyro cannot stall, this dramatic change of the rotor AoA means noting, just
more lift !
2. The change of gyro pitch does NOT change the rotor AoA, (if the stick is not
fixed to the dashboard...) like on the fixed wing.
So the only effect is swinging the cabin under the rotor !!!
What I am scared of, is that in an extreme case a long, tall tail can hit the blades !!!!
The centrifugal forces on the rotor will keep it flat, and the tail will be pushed
up against the baldes. PLEASE, correct me if I am wrong !
Of course this is a case described by Birdy, big HS on a gyro with no cabin.
Then the vertical Center of Drag from below is far behind the CoG and
we have high pitching moment.
If the area of the cabin and HS, as seen from below, are symmetric against the
CoG than there is no problem.
So, maybe not HS, CLT but the "harmony" as described by Mr. Magni and Greg Gremminger is what counts.
Big, long cabin (tandem) has to be balanced with big, long HS.
Short, no cabin gyro needs no HS.
For short, no cabin gyro long, big HS is DEADLY in an up wind-shear.
I know, nobody here has the cash to do wind tunel tests,
but maybe there is an objective way to settle this dispute
in a civilized way.
Please.
PTKay