So.

Helicopters have blades which are, crudely, like wings. Each blade can be tilted slightly, to alter its angle of attach and thereby its lift and drag. This happens not only in response to control inputs, but also dynamically as the blades rotate, to compensate for the fact that the blade is moving either with or against the helicopter's forward motion as it goes around.

The mechanical linkages needed to change the angle of attack of a rotating wing are nightmarish, as you might imagine.

So, an alternative.

On each blade, mount a little aileron. The aileron is on the trailing edge of the blade, near the tip so it has greatest airspeed over it. The blade itself is mounted in such a way that it can tilt up or down freely.

Now, the aileron is used to control the angle of attack of the main blade. Aileron up pushes the rear of the blade down, so the blade tilts up. And vice the opposite.

"So what?" I hear you ask. Well, the small aileron will not need a lot of power to move it, and can be driven either electrically or by compressed air bled into the rotor. And control can be via a sliding commutator on the main shaft, or even wirelessly.

This would, in particular, simplify the design of coaxial rotors, where a mechanical coupling to each of the stacked blades is even more nightmarish.
-- MaxwellBuchanan, Sep 01 2017

Buckler https://en.wikipedia.org/wiki/Buckler
Useful [8th of 7, Sep 02 2017]

Have you been in contact with [JesusHChrist] again?
-- normzone, Sep 01 2017


// blades which are, crudely, like wings. //

"Blades which are, on close inspection, wings"

Hence the appelation "rotary wing", a polite euphemism for "flying coffin".

// Each blade can be tilted slightly, //

Each blade can be tilted quite a lot ...

// to alter its angle of attach and thereby its lift and drag. //

The main concern is that it doesn't detach. That tends to be very loud and expensive.

// The mechanical linkages needed to change the angle of attack of a rotating wing are nightmarish, as you might imagine. //

Swashplates are quite simple ; just not outstandingly reliable, and therein lies the problem.

Tinker as you will, but it will still be a helicopter, which gets airborne only because a very large number of things fail to go wrong. And they don't "fly" - they're simply so ugly and frightening that the ground repells them.
-- 8th of 7, Sep 01 2017


Oh bugger. A bit more Googling after swashplates led me to an article on "servo flap helicopters", which reports:

"The servo flap is a small airfoil located at about 75 percent span of the rotor blade, situated on the trailing edge of each rotor blade. These flaps are controlled by the pilot through push-pull control rods and their function is similar to that of an elevator on fixed wing airplanes. Moving the trailing edge of the flap upward moves the leading edge of the main rotor blade up. This increases the rotor pitch or the lift in very much the same manner as the elevator, on a fixed wing aircraft, changes the angle of attack on the wing. Thus the helicopter pilot can cause the angle of attack of the flap to increase or decrease in pitch, causing the helicopter to alternately dive or climb."

So, that's another million down the drain.
-- MaxwellBuchanan, Sep 01 2017


<snigger>

But the design isn't commonplace. Care to explain why ?
-- 8th of 7, Sep 01 2017


[8th], have you looked at the great majority of humanity? Does it strike you that "commonplace" is not necessarily an entirely unqualified recommendation?
-- MaxwellBuchanan, Sep 01 2017


// why ? // At a guess it'd be because you still need a swashplate (albeit a lighter-build one) mechanism to provide the feedback to control the tabs.
-- FlyingToaster, Sep 01 2017


It would be almost impossible not to overcompensate using flaps to control blade pitch.
Like trying to balance a half full beer bottle on your finger.
-- 2 fries shy of a happy meal, Sep 01 2017


" At a guess it'd be because you still need a swashplate "

And some bucklers to hold it on.
-- normzone, Sep 01 2017


Aaar.
-- MaxwellBuchanan, Sep 02 2017


// And some bucklers to hold it on //

Shame on you, [norm].

A buckler is a small, round shield, held (by a right-handed combatant) by the left hand and wrist, the right hand holding the primary weapon, usually a sword but sometimes a dagger (for shipboard fighting, or FISH).

To swash a buckler is to sweep it energetically to distract an opponent, ward off a blow from their weapon, or strike them - either with the boss, or with the reinforced edge.

<link>

Read and inwardly digest. You will be asked questions later.
-- 8th of 7, Sep 02 2017



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