h a l f b a k e r yThis is what happens when one confuses "random" with "profound."
add, search, annotate, link, view, overview, recent, by name, random
news, help, about, links, report a problem
browse anonymously,
or get an account
and write.
register,
|
|
|
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.
Buckler
https://en.wikipedia.org/wiki/Buckler
Useful [8th of 7, Sep 02 2017]
[link]
|
| |
Have you been in contact with [JesusHChrist] again? |
|
| |
// 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. |
|
| |
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. |
|
| |
But the design isn't commonplace. Care to explain why ? |
|
| |
[8th], have you looked at the great majority of humanity? Does it strike you that "commonplace" is not necessarily an entirely unqualified recommendation? |
|
| |
// 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. |
|
| |
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. |
|
| |
" At a guess it'd be because you still need a swashplate " |
|
| |
And some bucklers to hold it on. |
|
| |
// And some bucklers to hold it on // |
|
| |
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. |
|
| |
Read and inwardly digest. You will be asked questions later. |
|
| |