Homebuilt Coaxial Helicopter (RELOADED)

quadrirotor

André MARTIN
How could be feasible this homebuilt version of the X2 Sikorsky coaxial helico...

No swashplate, only collectives.
A blown tail for yaw, pitch and roll (differential elevator...)
teetering semi rigid rotors with Delta3...

May be like the Rotorfly on wheels with a blown tail, no swashplate, only collectives!?
 

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quadrirotor

André MARTIN
Just for RC, too noisy, too inefficient, too dangerous...autorotation questionnable...a good drawing, only a good video game target.
 
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Rotor Rooter

Dave Jackson
MoTIS AIR BENDER

MoTIS AIR BENDER

Ga6riel,

Interesting.
It's proposed market is the same as Sikorsky's series of X2 craft.

Unfortunately the student's concept has a terminal flaw. Rigid 2-blade rotors will produce a horrendous 2P vibration. Sikorsky's earlier ABC coaxial had 3-blade rotors, which is much better, however vibration was the limiting factor to it's forward speed. It appears that the new X2 will have 4-blade rotors.


Dave
 

Timchick

Tim Chick
In a coaxial helicopter like that how do the rudder pedals pivot/turn the fusalage without a tailrotor? What exactly are the rudder pedals controlling?
 

brett s

Gold Supporter
In most the pedals would control either differential collective pitch or rotor tip brakes, in addition to actual rudder which would be effective at higher speeds - not sure with this one (fixed pitch, right?).
 

Jason O

Junior Member
I am almost sure that this helicopter uses collective and cyclic on both rotors. I believe the upper rotor is controlled by rods through the center of the mast just like the Mini 500, the and the Helisport copters. You can also control yaw by putting a brake on the two different rotor masts. When you cause friction between a mast and the airframe, the frame yaws that way.

Jason
 

PTKay

Gold Member
This looks to be really innovative.

The blade pitch control seems to be the same like Kaman,
with flaps on the trailing edge.

Simple teetering stiff hub bar.

Reliable and easy.
I really like it !!!
:)

Could be a solution for jump take off gyrocopters.
 
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Sita

Guest
....You can also control yaw by putting a brake on the two different rotor masts. When you cause friction between a mast and the airframe, the frame yaws that way......

Jason


Are you sure about this?:p
I think both rotors will slow down.....without any yaw at all.
 

Fly Army

Member
No auto capability

No auto capability

Isn't this the one that has no auto rotative capability ? I think I remember something about this one having a ballistic recovery chute. I could be mistaken though.
 

brett s

Gold Supporter
They say "excellent autorotating qualities" on their website - from watching the videos it sure looks like it has collective pitch, must be using blade servo tabs as PTKay suggested.
 

Sita

Guest
Cita;

I think it depend on how the two rotors are mechanically interconnected.
Here is a page related to this subject; Coaxial Transmission w/ Yaw Control

Dave
Dave,

I think that, from the moment the two rotors are connected,in whatever way,it makes no difference which rotor you put the brake on for yaw.Both rotors will slow down because they are connected,giving no yaw at all.
The only way to achieve yaw through the rotors is via an aerodynamic force (airbrake for example like in the Rotorcycle) or via a differential gearbox (like in the Japanese GEN-4 UL co-axial helicopter).....I think.
One can allways use two sperate rotorsystems, each having their own engine and rotor operating idependantly from each other, but I think that this will be tricky to control but that's the only way I can think of to use rotor shaft brake force to create yaw.

Cita
 
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