Electric motor 67 hp/30lbs

Hi Dave

Thanks for the explanation on the pulse width controller, have a little experience on these but not a lot. It has been mentioned that these units are very expensive for the model airplanes, limited market maybe? Anyway would like to persue this topic futher but wonder if maybe this should be move to "other components"?

Tony
 
Well Dave, no one has said "move it" so will continue the thread here. Read the tech paper on the controller on the link that you gave, very very informative, I maybe understood about 2 % of it but was able to conclude one thing. The motor is indeed quite simple and a marvelous piece of engineering, but the controller obviously came from the crash at Roswell in 1947. It is the controller where all the magic comes from. I suppose a kit could be assembled with the IC chips they discribe and not have to know the engineering behind them and just follow programming instruction, there is no way I could every commpletely understand how this functions in this life time, I'm just glad someone else does.

Understand it or not, this is what is shak'n and bak'n and where electric motor power is going.

Tony
 
WHY,

This is a very simple PWM controller. Anyone with a soldering iron and 15 bucks could buy and build it.

IMO, all recreational rotorcraft in the future will be powered by electricity. The migration of the electric motor to cars, and then to planes, and then to rotorcraft, may take place a lot faster then the reciprocation engine did.

Today's developers of future recreational rotorcraft would be very shortsighted if they did not think 'electric'. Of course, the motors, controllers and batteries will be buyouts, just as engines, etc are today.
no one has said "move it" so will continue the thread here
Perhaps there will be a Rotary Wing forum entitled
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Electrics
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in the future. :noidea:

Dave
 
Dave,

your last link is, in my view, a way to avoid dissipating power when not using 100% settings, and not suitable for brushless motors.

Here is a link to a series-production airplane electric-motor:

http://www.lange-aviation.com/htm/english/products/antares_20e/propulsion.html

They have recently flown a fuel-cell driven prototype (see the lange-aviation.com homepage). However, a hybrid system seems more realistic to me at this moment.

Certainly for the "Electics" thread.....
 
Here’s an article from the June, 1984 issue of Popular Mechanics magazine that got electro-fantasizers of that period all a twitter.
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The only usefulness of a helicopter with a duration of perhaps 3 minutes is as a tool to raise investor capital.

Some will remember Orlando Helicopter’s kits based on Sikorsky S-52 components, a GM V-8 engine and a very attractive original design fuselage.
 
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HI Dave

Have to agree with Walter on the simple PWM kit, am familiar with this type of controller, it is what you would use on present style DC motors for a pre-rotor. The ones that would have to be used on these new motors require phase angle sensors, rotor position sensors differential sensors, and load requirement sensors al mixed together and functioning like a Swiss watch in Miliseconds or Microseconds of time plus a lot of other action I don't understand. Fortunately that is left up to the engineers and designeers.

Now if the Naval Research Labs can just get their cold fusion experiments to repeat more reliabley we will have a winner-----------oops that would be national security and we can't have the public using that kind of tech, can we?
 
Walter & WHY,
Have to agree with Walter on the simple PWM kit
Have to agree with both of you on the simple PWM kit. :)

Some participants on the predecessor of this forum resisted the pursuit of new ideas; for various reasons. The simple circuit was posted as an enticement to those who previously had no interest in learning about electrics.

Most of us probably agree that billions of dollars is being spent and will continue to be spent on motors, controllers and energy storage. As you say, this should be left to, or contracted out to, the experts in these fields.

However, IMO, relatively little development has been done in the much smaller field of 'rotorcraft'. The opportunities for developing and adapting new rotorcraft concepts to the new electrical future will be a pleasuable chalange.
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Dave
 
Dave, where’s the freewheeling diode on your “simple PWM” or do you simply let the FET switch avalanche over?freewheeling.JPG
 
To get a little technical ....

To get a little technical ....

Walter,

Superficially, it looks like the power train on the Antaries 20E could be applied to a ultralight helicopter today. The motor's 'hollow shaft' will allow flight control rods to be passed to the rotor blades.

A single rotor helicopter craft would have to locate a custom 'hollow shaft' planetary gearbox between the motor and the rotor. A light version of this 1*2 AeroVantage could take two of the motors with virtually no modifications.

WHY,

You're going to scare people away. :D
A very basic controller need not have sensors. In a multi-phase motor there is always one phase that is temporarily not producing power. I believe that the back-EMF can be read from this phase and used by the controller to adjust the speed-torque at the propeller.


Dave
 
Chuck,

It appears that they don't even consider it on that wiring schematic. As I recall, on more significant diagrams they put a diode in parallel with each of the FETs.

Perhaps this will also relate to the use of the motor as a generator during autorotation, and at present this is beyond me.

Dave
 
When you switch off the current to an inductive load, Dave, The sudden collapse of the magnetic field causes a spike that must be dealt with, -that’s known as self induction and the spike has an amplitude that is proportional to the rate of current change; E =L(di/dt). It’s the same mechanism that burns up switch and relay contacts when switching inductive loads.

It also contains a sizable amount of energy that must be returned to the motor. That’s what a freewheeling diode does.

With high power PWMs driving large motors, there’s about the same amount of power dissipated in the freewheeling diode as in the FET switch. A high current Schottky is the diode of choice because of the low forward voltage drop.

Otherwise, you’ll zap the FET switch.
 
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Your right Chuck, and Zap a few of those special FET's and your pocketbook will be in intensive care quick!

Tony
 
15 minutes

15 minutes

I'd bet you could get 15 minutes of air time in a Bee with a seventy pound Lithium pack. Maybe 25 minutes with 140 pounds of Li. Would be cool, and fifteen minutes could be fun.

The real fun will be when and if the capacitor batteries come out, or that new secret battery from Europe.
 
While it would be nice to have a "electric gyro", at this point in time I think that the application of this new tech motor to the use as a pre-rotor is the most pressing need.

We have talked at great length in other threads as to why we have such a low membership and slow growth, there has been a lot of finger ppointing and accusations which have accomplished very little but here is a cold hard fact that cannot be denied.

We are in competition with the fixed wing world for interest and involvement. The powered Parachute is a very limited market and not having much luck in growing either. BUT, the fixed wing market is growing quite well especially with the introduction of aircraft like the "Back Yard Flyer" from www.valleyengineeringllc.com . We can boast all we want about our vertical decents and zero roll landings and being able to fly in rougher wind and our quick turns. However when we are put up against something like this aircraft that takes off in a VERY short distance, lands ina VERY short distance and uses a off the shelf engine with very little mod that eats about somewhere around 1 gallon a hour and flys at decent speeds, then we are in serious competition territory.

With the exception of a few models like Ernie's Dominator and some other that are near clones that can really do a impressive pre-rotate short take off, we are very weak in the impression department when we eat up several hundred feet of runway trying to get airborne. If we are going to make a competitive impression on the prospective public, we are going to have to consistently have take off's like SuperFly did in his video Superfly meets Goped (in another thread ). This is where I would hope the new tech electric motor will provide a much needed boost in take off performance.

Many years ago I was told that when you replace a electric motor with a gas engine and want the same amount of performance, you will need to replace a 1 hp electric motor with a 2.5 ( or bigger) hp gas engilne. Don't know where these figures came from but they sure seem to have been correct. So it looks like if we can get a 3 or 4 hp motor of the new design and comparable weight to what is being used, then we can expect some SERIOUS pre-rotation performance and start attracting more attention from the prospective public for members. The motor could be head mounted or mounted else where and shaft driven, what ever the need maybe. While the Back Yard Flyer is ultralight I don't think we have to compete there because this is a double edge sword, on the good side it lets those who have lots of experience flying and maybe have lost a medical get back into flying or others who have the training and just want a fun machine, it also lets those who have no experience, no training or a bad attitude, get in a aircraft and do something stupid.





Tony

PS still think we should move this to "other components "
 
Chuck,

You raise an interesting subject which certainly needs more studying, on my part at least.

I think that a brushless DC motor is controlled by pulse width modulation (PWM) and that it will require two field effect transistors (FET) to replace the split-ring commutator of a brushed DC motor. I.e. a FET to handle the current flow in each direction. The motor will require multiple phases to be efficient and therefore a 4-phase motor will require 8 FETs.

The on/off switching of these FETs will have durations of milliseconds. It appears that most metal oxide semiconductor field-effect transistors (MOSFET) have a built in diode. However, the ability of these diodes to handle exceptionally high loads may be limited. Apparently, controller technology is advancing along with that of motors and storage devices since it was mentioned a few months ago that insulated-gate bipolar transistors (IGBT) are starting to replace MOSFETs.

It will also be necessary for the Schotty diode or its alternative circuit to let some of the back-EMF from the unpowered coil get back to the controller so that it can be used for speed-torque control, if encoders are not used.

Perhaps this is the fun and the frustration of pursuing new fields.
Perhaps it is also the reason for a separate 'Electric' forum. :)

Dave
 
To raise a 550 lb. weight at the rate of one foot per second requires one HP whether it comes from a mule or a gas turbine.

In traction applications, where a vehicle must be started from a standstill, a DC electric motor will beat an IC engine every time because maximum torque occurs at zero speed.

A diesel/electric railway locomotive combines the best of both; the diesel engine is governed to run at its ideal speed and excitation to the coupled generator is varied to control power to the electric traction motors, providing an infinitely variable transmission.

Diesel/hydraulic locomotives have been built using variable displacement pumps to drive the traction motors.

But with electric helicopters, the machinery is the easy part; toting enough electricity to be useful is the problem yet to be solved and in my opinion, is far over the horizon.
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Don’t confuse brushless DC motors with AC induction motors.

A brushless DC motor is just that; semiconductors have replaced commutator and brushes.

An AC induction motor is one in which multiphase alternating current creates a rotating magnetic field that in effect, drags the rotor around with it. Starting torque is low and speed range is limited. It’s not happy with anything but sine waves; some of the harmonics of rectangular “quasi” sine waves tend to cause reverse rotation. Most of the harmonics end up as waste heat.
 
Brent,

Apparently the Yuneec Paramotor uses the Plettenberg - Predator 37 motor.
Here is design information on a helicopter that would uses a couple of these motors ~ Electrotor-Simplex.

This helicopter could be built today, however, it would be extremely dangerous due to the reliability of the small motor. It would only be good for trying to claim the record for first manned electric powered flight by a rotorcraft.

The Electrotor-Simplex is still valid as a prerotor and partially powered rotor for a gyrocopter.

Dave
 
But with electric helicopters, the machinery is the easy part; toting enough electricity to be useful is the problem yet to be solved and in my opinion, is far over the horizon.

Chuck,

That maybe the good news. It will give interested people some time to develop the rotorcraft side of the electric helicopter while others are improving the storage devices.
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Machinery wise, there’s not much to develop for an electric helicopter. The electric motor and controller from a Toyota Prius would work fine for a small helicopter. The only problem would be keeping the electric stuff cool; automobiles at a steady 60 mph use perhaps 10% of maximum rated power.

The Orlando Helicopters electric helicopter actually did lift off in 1984/85.

Perhaps the ton of batteries could be towed behind in a blimp.
 
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