Really cool video on the mechanical ignition timing control in a delorean to control emissions. Explanation of ignition advance at the end: https://www.youtube.com/watch?v=ge1GwepqtK0
"How about we just add a simple device that associates the pitch of the blade with the torque, and let a computer figure out how to spin the motor to get the pitch we want? No linkage!"
Yeah, that is dang clever.
I assume you mean the motor rotation angle. It's probably not a brush motor, but a 3-phase synchronous motor. That means instead of having a commutator to apply the voltage to the coils, a computer switches some FETs to apply the voltage. In the simplest case, the rotor is assumed to follow the applied voltage waveforms. In a more typical system, the rotor position is estimated from the applied phase voltages and measured currents (usually via PLL or a sliding mode observer).
If you mean "how do they determine the blade pitch?" then the answer is that they don't need to. The controller - weather that's a computer with inertial sensors, or a person watching it - will just manipulate the amount of torque variation until it gets the response that it wants from the copter. Much like you don't actually need feedback of your cars gas pedal position so long as you have vehicle speed feedback.
This means either including a crankshaft and optionally a system of gears to route the rotational power along the axes you want the rotation in, or ducting the output of a jet turbine in some way that drives the rotors. In addition, there are different limitations with regards to the time required for a given change in RPM as compared to an electrical motor.
My impression is that a lot of the complexity in conventional helicopters (and flying machines in general) stems from the limitations of combustion engines. There's a reason that you very rarely see vectored thrust in conventional airplanes, for example.
Of course, if batteries and electric motors become sufficiently powerful, this changes the dynamic and it will become possible to design electric aircraft that re-evaluate the traditional design restrictions. This is one of the reasons that the rapid progress of electric cars is so exciting.
With full sized helis, it takes a long time to spin up the rotors to speed before the pitch is changed to take off.
I don't see a specific reason why this wouldn't scale. I do wonder what changes in load do to the system though. If it can't handle changing loads without messing up the blade dynamics, it would only work for fixed payload systems like camera platforms.
http://www.smithsonianmag.com/videos/category/history/the-se...
Directional control is achieved by leaning, the gyroscopic forces from the dual rotating blades creates inherent stability without any feedback system. They are like segways of the sky. Reports say it only took 20 minutes for a non pilot to learn how to fly it. These machines are incrdible and I don't understand why more hasn't been done with them.
A late 1970's version called the williams x jet WASP added a cruise missle turbojet for more horsepower, and was coined the "flying pulpit".
People here might also be interested in the Mosquito Air helicopter as well. It falls into this ultralight classification and is a kit you can build in 200-300 hours. It costs about $30,000...
I'm not a mechanical engineer, though.
In a way this is similar: they start with two actuators that seem very limited in what they can accomplish: you can only speed them up and down. By modulating the speed of both motors in sync, they are able to control that cheap rotor mechanism they came up with, achieving 6DoF [3]
1: http://en.wikipedia.org/wiki/Pulse-width_modulation
It's a cool idea. Human size helicopters would love to avoid all that blade-pitch complexity. :)
[1] an axially-symmetric imaging system could compensate easily, e.g. a panoramic system.
The issue when flying is that they balance as if they are on a ball. You need to constantly adjust the controls to stop from "falling off the ball". Go the wrong direction and you speed up the rate at which it falls. When it is facing away from you, that's not very hard. When it is facing towards you everything is backwards. When you are turning, the correct direction to stay balanced is constantly changing.
Automated systems can do this automatically for you though, so a drone-like autopilot in a standard helicopter could make them as easy to fly as quadcopters. Traditional helicopters are still mechanically complex though. This system looks to fix that. And this would be more efficient than a multirotor.
I'm currently on a quest to design highly functional robots that can be made with just a 3D printer and a minimum of external parts - so far only bearings, motors, drive belts, batteries and electronics are the non-printed parts needed. I make everything so that it fits together by interlocking or with minimal use of some coarse printed fasteners.
Since nothing needs to be bought from the store that won't be useful if the design changes, it is trivial to iterate and build a newer version.
My hope is that with developers worldwide working on improvements, injection molded versions of the parts would become obsolete before the mold was even cut.
When it comes to manufacturing, 3D printing is a whole different ballgame. No other manufacturing technique can make so many complex parts without human intervention. This means it opens up all new possibilities for how we manufacture things - like continuous iteration of shipping hardware.
Injection moulding is only lower cost when you want to buy something that is already mass manufactured or millions of identical things. Up to about 10,000 units, 3d printing is cheaper.
Experiment and explore without the wait for Mr. FedEx.
These other components look printable too. Right now I am making 3D printable robots that don't need any non-printed parts aside from motors, bearings, and drive belts (and batteries and electronics).
So these definitely should be printable at home.
