Half a croissant, on a plate, with a sign in front of it saying '50c'
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CVT Aircraft

A 3 bladed helicopter which uses only one engine
  [vote for,

Apparently I reinvented the CVT last night. I was envisioning a flying machine which has a cabin surrounded by 3 blades, but is powered off only one engine. The blades are positioned triangularly around and above the cabin. The engine has variable diameter pulleys that drive the blades allowing the pilot to the rate of rotation for each blade independently while not changing the central motor's rate.
bleh, Sep 09 2007

Draganflayer http://www.andybrai...ras/draganflyer.htm
[2 fries shy of a happy meal, Sep 09 2007]


       I assume you mean three rotors, not three blades. Which would be at least six blades. And how do you surround something three dimensional with only three planar surfaces? I think you will need at least four rotors.   

       Oh, and why do you want to do this? What is this accomplishing?
Galbinus_Caeli, Sep 09 2007

       I guess I wasn't clear. I did mean 3 rotors, each consisting of 3 blades.   

       The rotors are positioned in a single horizontal plane above the cabin where the drive shaft of the engine protrudes (the same plane that a traditional helicopter rotor resides in).   

       Why, shirley this is no place for that question. Honestly, because the mental picture I had flicked on that little light that make you want to do something just because. It may not work, its not very well thought out, and its most likely no better than any existing system. But it would look cool and different and it was an interesting thought. At least to me.
bleh, Sep 09 2007

       Ah! So they are all coplanar above the cabin. One going clockwise and the other two counterclockwise (anticlockwise). Or vice versa. In that case you are going to need to do something to keep the cabin from spinning in the direction of the odd rotor. An internal gyroscope or external tail rotor would do it.   

       This will be a bitch and a half to fly, but so what, that is what fly by wire and test pilots are for, right?
Galbinus_Caeli, Sep 09 2007

       Like this [bleh]?
but with three rotors and one motor?

       Yes, sort of like that 2 fries, but with 3 rotors.   

       If the frame the rotors are attached to is mounted directly to the cabin, would it still need something to keep the cabin from spinning?   

       also, why is there an odd rotor? it seems to me they will all be spinning the same direction, but I may be visualizing it wrong.
bleh, Sep 09 2007

       Two rotors are typically set up to counter rotate, one clockwise, one anticlockwise (counterclockwise). That way the torque cancels out. Three rotors(or any odd number) would not be able to do this, so there will always be some torque that needs to be dealt with or the cabin will spin.
Galbinus_Caeli, Sep 09 2007

       //Two rotors are typically set up to counter rotate, one clockwise, one anticlockwise (counterclockwise). That way the torque cancels out.//   

       Would you still need to do this if the rotors are not on the same axle? Having one rotate the opposite direction would complicate things.   

       It's probably clear by now but I am no engineer [yet (another 2 years)].
bleh, Sep 10 2007

       Yes, this is just a matter of Newtonian physics. If a motor tries to spin a shaft one way, the motor is going to try to spin the other. If you use a drive train to split the spinning mass into equal parts going opposite directions (or use two power plants) they counter act each other.
Galbinus_Caeli, Sep 10 2007

       With 3 rotors the cabin will rotate unless one of the rotors is rotating in the opposite direction to the other 2 at twice the speed (or has twice the area).   

       I can see no advantage to this arrangement.   

       I think what you are aiming for could be achieved fairly easily with a layout of 4 rotors and I'm pretty sure I've seen that somewhere.   

       Using 3 rotors you could have a main rotor slightly behind the centre of gravity and 2 smaller maneuvering rotors in front and out to the sides. As with most helicopters, the rotational speed of the 3 rotors can be linked, with only the pitch being altered independently. This would be a lot more complicated to fly that the 4 rotor arrangement and would only allow a more fixed-wing aeroplane style of flying, eliminating some of the maneuvers possible in a helicopter.
marklar, Sep 10 2007

       Well, I still don't understand fully, but I havent diagramed it or put any research into it at this point.   

       The only real reason I went w/3 rotors as opposed to 4 is because I thought 3 would look cooler. 4 Is fine by me.   

       Alternatively, can the 3 rotor version all rotate the same way with each rotor having a slight pitch to counteract the rotation of the cabin?
bleh, Sep 10 2007

       If anything other than exactly half of the rotors are rotating each direction, you are going to have torque to deal with. (assuming rotors are the same size, same speed, yada yada). There are ways to deal with this. The very traditional tail rotor for one. Or the motor could be spinning freely on bearings inside the cabin. Or you could have six rotors in three counter-rotating concentric pairs (three shafts with two rotors on each, one above the other spinning in opposite directions). The last option might give you the look you are seeking.
Galbinus_Caeli, Sep 10 2007

       //Or the motor could be spinning freely on bearings inside the cabin.// So, motor at 3000rpm clockwise, and blades at 100rpm anticlockwise? Hmmm.
MaxwellBuchanan, Sep 10 2007

       Well, maybe not freely. Put a brake and some automatic controls and I bet it could control yaw pretty effectively.
Galbinus_Caeli, Sep 10 2007


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