How can a tailless tiltwing aircraft be balanced when the location of the center of gravity is located slightly below and aft of the aerodynamic center? How can such a cg placement be analytically determined before simulations are carried out?
firstly ensure the propellers counter rotating, then axis of rotation inclined to provide vectors for lift and thrust
I'm making some assumptions about your question:
1. "tailless" - means no separate aerodynamic surfaces for controlling pitch in wing-borne flight mode, and no tail rotor for pitch control
2. "tilt-wing" - the aircraft is capable of hovering flight or VSTOL. There is at least one rotor on each wing, the transition is performed by tilting the wing-rotor whole assemble.
The design and control in wing-borne cruise mode needs to follow tailless aircraft designs, e.g. reflex air-foils, or swept wings and washout, and elevons for pitch/roll control. For yaw stability and control most likely you need a vertical fin and rudder, or use Prandtl's bell shaped distribution for the wing's lift to eliminate adverse yaw, and use spoilers for yaw control.
If CG is aft of AC your aircraft is not stable, you'll need some kind of artificial stability.
For hovering flight you'll need to ensure adequate control in yaw, pitch and roll. Pitch can be controlled using cyclic, or by control surfaces in the rotor's slipstream - e.g. wing's elevons. Roll can be controlled using some kind of differential thrust - rotor collective or motor power control. Yaw control could be implemented using torque differential between rotors, they need to rotate in opposite directions as Mohamad Afifi mentioned.
A good primer book concerning these matters is "Vertical Takeoff and Landing Aircraft" by John Paul Campbell
Using a horizontal controlled tail. Its calculation is based on well-known methods. More precisely on experiments in a wind tunnel.
I would suggest a movable ballast in the sense of X axis, i.e. a cylinderto be slided along a bar with a system of motor, pulleys and a steel wire similar to the one used for flight controls
- Badges
- Science topic