A challenge ~ for those who are not technically challenged.
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A challenge ~ for those who are not technically challenged.
In January a link to this web page was posted. Hughey Electricopter Corporation
This week the following e-mail was received;
An all electric craft for $10,000 dollars sounds intriguing.
Based on the limited information, any speculation as to what its features are?
There is (currently) no reward for a winner,
Dave
[It is assumed that Mr. Brad Hughey will not find fault with this little bit of advance-promotion.]
This week the following e-mail was received;
"Dave,
I’m flattered that you actually put a message with a link to our “placeholder” web page on a rotary forum.
Frankly, we’re still in stealth mode, but “the cat will be out of the bag” so-to-speak when our first U.S. Patent Application is published by the USPTO in November.
As the name would suggest, the full-size (part 103) flying proof-of-concept prototype is all electric, fly-by-wire, and nothing like anyone has ever seen before.
We won’t be ready for a public demonstration until next spring, as we’re still doing IGE control trimming and the Chicago weather is not kind in the winter.
Since multiple rotors is your thing, I think you’ll want to kick yourself when you see it.
The miracle is how cheaply we can crank these out (although the production prototype is a year away).
Let the revolution begin!
Regards,
Brad Hughey
Founder & CEO
Hughey Electricopter Corporation"
I’m flattered that you actually put a message with a link to our “placeholder” web page on a rotary forum.
Frankly, we’re still in stealth mode, but “the cat will be out of the bag” so-to-speak when our first U.S. Patent Application is published by the USPTO in November.
As the name would suggest, the full-size (part 103) flying proof-of-concept prototype is all electric, fly-by-wire, and nothing like anyone has ever seen before.
We won’t be ready for a public demonstration until next spring, as we’re still doing IGE control trimming and the Chicago weather is not kind in the winter.
Since multiple rotors is your thing, I think you’ll want to kick yourself when you see it.
The miracle is how cheaply we can crank these out (although the production prototype is a year away).Let the revolution begin!
Regards,
Brad Hughey
Founder & CEO
Hughey Electricopter Corporation"
Based on the limited information, any speculation as to what its features are?
There is (currently) no reward for a winner,
Dave
[It is assumed that Mr. Brad Hughey will not find fault with this little bit of advance-promotion.]
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Not sure it's such a good thing to be pushing this design into the open yet, Dave, although it's one i'll keep my eyes on. The guys at Hughey are saying next spring for the demo so i would leave it until then. This means that if they have 11th hour bugs to get sorted they haven't got an expectant public clamouring to see, or shareholders banging on the table. Too many projects in engineering fail because they went public before they were absolutely ready, and i'd like to see a success here. 
A general discussion about how such a design might be accomplished is fine though. My take would be that an electric rotorcraft endurance would be at best minutes, so more a weekend hobby thing than application driven. Best powertrain would be a motor running at high RPM with the reduction box driving coaxial rotors. Powerpack would best be NiMH with inbuilt charger/conditioner allowing direct plug in to the mains.
I'm still not convinced that for a given torque output a direct drive pancake motor weights less than a high RPM motor through several epicyclic stages, since even with negligable flux circuit iron you still need a finite amount of copper to pass enough total current in the 1 Tesla B-field that NdFeB magnets generate (2 max if flux concentrated). I don't have time to websurf (revising), but there are plenty of formulas/methods to estimate gearbox size hence mass - epicyclics are the lightest.
Lest Nick show us up again with another napkin calc!
Mart
A general discussion about how such a design might be accomplished is fine though. My take would be that an electric rotorcraft endurance would be at best minutes, so more a weekend hobby thing than application driven. Best powertrain would be a motor running at high RPM with the reduction box driving coaxial rotors. Powerpack would best be NiMH with inbuilt charger/conditioner allowing direct plug in to the mains.
I'm still not convinced that for a given torque output a direct drive pancake motor weights less than a high RPM motor through several epicyclic stages, since even with negligable flux circuit iron you still need a finite amount of copper to pass enough total current in the 1 Tesla B-field that NdFeB magnets generate (2 max if flux concentrated). I don't have time to websurf (revising), but there are plenty of formulas/methods to estimate gearbox size hence mass - epicyclics are the lightest.
Lest Nick show us up again with another napkin calc!
Mart
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sprocket,
Probably a thank you note.
Graviman,
True. However, Mr. Hughey has said next to nothing about his design; other than mentioning a few parameters such as; empty weight under 254 lbs., vertical takeoff and landing capability, all electric power and controls, and under $10,000.00.
True. A discussion could be fun and perhaps rewarding.
Here's my suggestion for the PPRuNemobile;
It's called a PPRuNemobile because the craft will have the same effect as prunes. Partake of either and one will **** their pants. However, I digress.
Take this full set of plans for a Hornet gyrocopter and disregard the engine, propeller, transmission, fuel tank and most of the control components.
Acquire two Predator motors, their controllers, and a pair of propellers
Install one motor and propeller in each blade, at approximately 1/3 of the blade's span.
Oh, and weld the conventional gyrocopter longitudinal and lateral rotor pivots so that they no longer tilt.
So far the craft is similar to a conventional Ultralight gyrocopter, except that is does not have any controls.
Now for the neat stuff;
Collective control: The pilot's controller has a single throttle, which determines the rotational speed of both the motors and their propellers. As each motor-propeller assemble rotates about the craft's mass, the gyroscopic precession of this assembly wants to pitch it and blade up. In other word, the faster the motors rotate, the faster the rotor will rotate and also the greater the blade pitch will be due to the blade twist that is imparted to it.
Now for neater stuff.
On the retreating side, during forward flight, the propeller does not have to produce as much torque. Its rotational speed therefore increases and this greater rotational inertia results in the retreating blade having a higher pitch than the advancing blade.
Now for neatest stuff.
Cyclic control: To increase the pitch of a blade when it is at a specific azimuth while decreasing the pitch of the opposite blade, simply involves a temporary increase in the rotational speed and inertial of one motor while the other motor experiances a decrease. This is done by temporarily (cyclically) adding a electrical 'spike' to one motor while causing the other to become a generator and thereby slow down.
All in serious fun.
Dave
why dont you give them some money and see what they send you.
Graviman,
Not sure it's such a good thing to be pushing this design into the open yet,
A general discussion about how such a design might be accomplished is fine though.
Here's my suggestion for the PPRuNemobile;
It's called a PPRuNemobile because the craft will have the same effect as prunes. Partake of either and one will **** their pants. However, I digress.
Take this full set of plans for a Hornet gyrocopter and disregard the engine, propeller, transmission, fuel tank and most of the control components.
Acquire two Predator motors, their controllers, and a pair of propellers
Install one motor and propeller in each blade, at approximately 1/3 of the blade's span.
Oh, and weld the conventional gyrocopter longitudinal and lateral rotor pivots so that they no longer tilt.
So far the craft is similar to a conventional Ultralight gyrocopter, except that is does not have any controls.
Now for the neat stuff;
Collective control: The pilot's controller has a single throttle, which determines the rotational speed of both the motors and their propellers. As each motor-propeller assemble rotates about the craft's mass, the gyroscopic precession of this assembly wants to pitch it and blade up. In other word, the faster the motors rotate, the faster the rotor will rotate and also the greater the blade pitch will be due to the blade twist that is imparted to it.
Now for neater stuff.
On the retreating side, during forward flight, the propeller does not have to produce as much torque. Its rotational speed therefore increases and this greater rotational inertia results in the retreating blade having a higher pitch than the advancing blade.
Now for neatest stuff.
Cyclic control: To increase the pitch of a blade when it is at a specific azimuth while decreasing the pitch of the opposite blade, simply involves a temporary increase in the rotational speed and inertial of one motor while the other motor experiances a decrease. This is done by temporarily (cyclically) adding a electrical 'spike' to one motor while causing the other to become a generator and thereby slow down.
All in serious fun.
Dave
Last edited by Dave_Jackson; 18th Sep 2006 at 05:00.
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Well in theory yes. I suspect that in practice getting the pitch return spring to balance each blade tip prop precession in all flight conditions would not be easy, you could use the aerofoil section. With the time lag to accel and deccel the prop it doesn't sound like the most effective control mechanism either. Besides the idea of putting a gyroscopic control system on the end of a flexible blade with aeroflexure makes me very uneasy. Even if you get the blade to behave itself, any departure could be catastrophic.
Remember the Lockheed Electra which crashed due to prop bearing wear allowing precession to match a wing eigenmode? I would keep the original control mech.
The YAK55 model prop looks about ~0.5 meter diam, so with 2 you have ~0.7 m. This is getting on for a microcopter tail rotor diam so efficiency is not so bad. Using the original low disk loading rotor helps, and the prop will help reduce tip vortex strength.
Assuming you can hover at 20kW, and using the Duracell figure of 144Wh/kg (partly since Wikipedia figure of 60Wh/kg for NiMH seems low, and partly because i am too lazy to get proper NiMH figures
). This is 8.64 kW-min/kg, so you need 2.3kg of battery for every minute of flight. A 10 minute joyride is already up to 23kg of battery (55 kg if you believe wiki).
Get it wrong and the pilot will not enjoy the experience...
Mart
Remember the Lockheed Electra which crashed due to prop bearing wear allowing precession to match a wing eigenmode? I would keep the original control mech.
The YAK55 model prop looks about ~0.5 meter diam, so with 2 you have ~0.7 m. This is getting on for a microcopter tail rotor diam so efficiency is not so bad. Using the original low disk loading rotor helps, and the prop will help reduce tip vortex strength.
Assuming you can hover at 20kW, and using the Duracell figure of 144Wh/kg (partly since Wikipedia figure of 60Wh/kg for NiMH seems low, and partly because i am too lazy to get proper NiMH figures
). This is 8.64 kW-min/kg, so you need 2.3kg of battery for every minute of flight. A 10 minute joyride is already up to 23kg of battery (55 kg if you believe wiki).Get it wrong and the pilot will not enjoy the experience...
Mart
Last edited by Graviman; 18th Sep 2006 at 21:23. Reason: Because my brain is tired, and i'm out of coffee!
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Graviman,
The simple [electric&gyroscopic] idea could be kept for the collective control and a conventional gyrocopter cyclic control could be used in lieu of the proposed electric cyclic control. This will make the craft simpler and safer. Web page.
However, it deviates from Brad Hughey's " fly-by-wire", and the fun is the challenge to try and guess what his concept might be.
Dave
The simple [electric&gyroscopic] idea could be kept for the collective control and a conventional gyrocopter cyclic control could be used in lieu of the proposed electric cyclic control. This will make the craft simpler and safer. Web page.
However, it deviates from Brad Hughey's " fly-by-wire", and the fun is the challenge to try and guess what his concept might be.
Dave
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This indicates our different approaches to such a problem, Dave!
Since i expect to get shouted at if the design doesn't work, i will go for the simplest solution to the problem. Since your interest is in the technological concept, you will go for a complicated solution which captures a particular mechanism.
From Hughey's email i just assumed it was a 4 rotor design, with seperate FBW control motors driving though integral epicyclic gearboxes! I imagine the blades are self aligning to optimum AOA, likely on teetering hubs.
Using the precessing props to control collective pitch won't produce cyclic blade departure. But... don't forget that one design condition has to be failed motors (most likely from flat batteries). You have to allow the pilot to flare from an auto, and no motors means no control (even worse if it was cyclic too). Actually this would also be a failing of the above system too, unless there is a "flare reserve".
It's about this point in the project that i expect the shouting to start...
Mart
Since i expect to get shouted at if the design doesn't work, i will go for the simplest solution to the problem. Since your interest is in the technological concept, you will go for a complicated solution which captures a particular mechanism.
From Hughey's email i just assumed it was a 4 rotor design, with seperate FBW control motors driving though integral epicyclic gearboxes! I imagine the blades are self aligning to optimum AOA, likely on teetering hubs.
Using the precessing props to control collective pitch won't produce cyclic blade departure. But... don't forget that one design condition has to be failed motors (most likely from flat batteries). You have to allow the pilot to flare from an auto, and no motors means no control (even worse if it was cyclic too). Actually this would also be a failing of the above system too, unless there is a "flare reserve".
It's about this point in the project that i expect the shouting to start...
Mart
Last edited by Graviman; 19th Sep 2006 at 18:23. Reason: Forgot to deselect sim mode before activating brain.
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Mart,
You may very well be describing what Mr. Hughey is developing. Perhaps varying the power of four independent rotors is his intended means of handling all flight control.
Why? The highly promoted AirScooter doesn't even have the ability to Autorotate. 
Meanwhile back in the land of practicality. My previous mention of conventional gyrocopter cyclical control may not work. This is because the pilot would probably be required to exert strong forces on the cyclic stick to overcome the motor&prop's gyroscopic resistance to change. So, it's back to the earlier mentioned electric cyclic control.
Reliability should not be a concern if redundancy was incorporated in everything electrical; from the batter-packs, to controllers, to the windings within the motors.
Dave
You may very well be describing what Mr. Hughey is developing. Perhaps varying the power of four independent rotors is his intended means of handling all flight control.
But... don't forget that one design condition has to be failed motors.
Meanwhile back in the land of practicality. My previous mention of conventional gyrocopter cyclical control may not work. This is because the pilot would probably be required to exert strong forces on the cyclic stick to overcome the motor&prop's gyroscopic resistance to change. So, it's back to the earlier mentioned electric cyclic control.
Reliability should not be a concern if redundancy was incorporated in everything electrical; from the batter-packs, to controllers, to the windings within the motors.
Dave
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aeromys
Why? Are you trying to get beyond the range of the craft?
I don't think that fly-by-wire will have any detrimental effect on the range. The control circuit should be insignificant because it will only be 5 or 12 volts.
The power circuit will not be expending any power on electro-mechanical blade-pitch devices. All power will go into rotating the rotor, via the two propellers, The power to change the pitch of the blades will just be an increasing and decreasing of the mean rotational power.
If this is not a satisfactory answer to your concern,
say so.
_____________________________________
Sketches add to web page to show two alternative means of effecting blade pitch.
Dave
I'll get my coat.....
I don't think that fly-by-wire will have any detrimental effect on the range. The control circuit should be insignificant because it will only be 5 or 12 volts.
The power circuit will not be expending any power on electro-mechanical blade-pitch devices. All power will go into rotating the rotor, via the two propellers, The power to change the pitch of the blades will just be an increasing and decreasing of the mean rotational power.
If this is not a satisfactory answer to your concern,
say so._____________________________________
Sketches add to web page to show two alternative means of effecting blade pitch.
Dave
Last edited by Dave_Jackson; 19th Sep 2006 at 22:10. Reason: To add note re change to web page.
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Originally Posted by DJ
The highly promoted AirScooter doesn't even have the ability to Autorotate.
Originally Posted by DJ
My previous mention of conventional gyrocopter cyclical control may not work. This is because the pilot would probably be required to exert strong forces on the cyclic stick to overcome the motor&prop's gyroscopic resistance to change. So, it's back to the earlier mentioned electric cyclic control.
Besides high mass 1/3 along a finite section blade? You were championing rigid rotors at one point! I am not an expert aerodynamicist, but one immediate concern is the velocity gradient across the prop. The solution is too much of a leap into the unknown, unless the benefit justifies the investment.
Above a certain rotor size RRPM reduction (for tip speed) makes blade jets/props more weight effective. For a one man machine i just don't think it is worth the complexity. By trying to avoid a tail rotor, or counterrotation, you are introducing all sorts of new problems.
Mart
Last edited by Graviman; 1st Oct 2006 at 09:00.
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Brief lunchtime google for epicyclics:
Dave, since you seem adverse to epicylic g/boxes in your motor concepts:
http://www.uts.com/ResourceCenter/Tu...calculation%22
http://www.roymech.co.uk/Useful_Tables/Drive/Gears.html
Software:
http://www.uts.com/ResourceCenter/Pr...on%20radius%22
Useful resource maybe:
http://www.powertransmission.com/gtforums/qanda/
Far too technical for concept evaluation:
http://gltrs.grc.nasa.gov/reports/19...on%20radius%22
http://ntrs.nasa.gov/archive/nasa/ca...on%20radius%22
General:
http://scholar.lib.vt.edu/theses/ava...on%20radius%22
http://www.bga.org.uk/publish/techpu...vib-Biblio.htm
The point is that this is a well established technology. Apart from investment in time and tooling (or use standard parts), a concept using this will work - otherwise i had better start designing toasters for a living!
Mart
http://www.uts.com/ResourceCenter/Tu...calculation%22
http://www.roymech.co.uk/Useful_Tables/Drive/Gears.html
Software:
http://www.uts.com/ResourceCenter/Pr...on%20radius%22
Useful resource maybe:
http://www.powertransmission.com/gtforums/qanda/
Far too technical for concept evaluation:
http://gltrs.grc.nasa.gov/reports/19...on%20radius%22
http://ntrs.nasa.gov/archive/nasa/ca...on%20radius%22
General:
http://scholar.lib.vt.edu/theses/ava...on%20radius%22
http://www.bga.org.uk/publish/techpu...vib-Biblio.htm
The point is that this is a well established technology. Apart from investment in time and tooling (or use standard parts), a concept using this will work - otherwise i had better start designing toasters for a living!
Mart
Last edited by Graviman; 20th Sep 2006 at 11:45. Reason: Coffee spillage...
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Mart,
There is no adversity to epicylic gearboxes. They have a good power/weight ratio and are used in many helicopters. In fact, the SynchroLite uses a pair of them in its final reductions. [Final Reduction]
My proposal is just one idea. The intent of this thread was for a number of ideas to be proposed, and discussed.
You may be correct. Brad Hughey has just placed his first two posts to a thread (on a different forum). He provides a link to Towards Dynamically-Favourable Quad-Rotor Aerial Robots
_____________________
More ideas needed.
Dave
There is no adversity to epicylic gearboxes. They have a good power/weight ratio and are used in many helicopters. In fact, the SynchroLite uses a pair of them in its final reductions. [Final Reduction]
My proposal is just one idea. The intent of this thread was for a number of ideas to be proposed, and discussed.
From Hughey's email i just assumed it was a 4 rotor design.
_____________________
Forget my idea. ~ The aerodynamic inefficiencies of a propeller mounted on a rotating blade, combined with the intrinsic inefficiency of the rotating blade probably make my idea unattractive. Its efficiency is far less than that of mounting a propeller on the non-rotating wing of an airplane.
More ideas needed.
Dave
Last edited by Dave_Jackson; 21st Sep 2006 at 04:19. Reason: To forget my idea.
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Originally Posted by DJ
More ideas needed.
Seriously, if the purpose of this concept is e-drive, go with conventional or coaxial. The smart part is in the g/box and powertrain. As an aiming point go for 10 mins flight per batt pack.
Mart
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Back about 1975 there was model helicopter with an unusual rotor drive.
It had a vertical gas engine bolted on top of the rotor head with a large prop above. The torque from the engine turned the main rotor and the prop blast straight down added thrust also. In effect, it worked like a gearbox and clutch without the parts.
And no tail rotor Dave.
It had a vertical gas engine bolted on top of the rotor head with a large prop above. The torque from the engine turned the main rotor and the prop blast straight down added thrust also. In effect, it worked like a gearbox and clutch without the parts.
And no tail rotor Dave.
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A prop tip rotor drives the blade tip prop?
Back about 1975 there was model helicopter with an unusual rotor drive.........
The idea has been modified by moving the propellers further outboard, reducing their diameter, and increasing their pitch.
This should improve the efficiency.
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Hi Guys,
I've been watching this thread for a bit and thought I would chime in with a question. I like the idea of a $10k helicopter I can't help but think about the cost of the replacement batteries. If we are looking at 2.3 Kg of battery per minute of flight as Graviman suggested and we want to fly more than 10-15 minutes we would have to have a pretty good size battery pack I'm guessing. How many charge/discharge cycles are NiMH batteries good for before requiring replacement? It would really suck to have a $10K helicopter that flies for 30 minutes on every charge but you have to spend $100K on batteries after 10 flights! I'm sure it wouldn't be that bad but I figured I would bring it up and see what you all thought. I know most of this thread has been about how to make the thing fly and not how to make it practical but I think it is an added aspect to the challenge.
Max
I've been watching this thread for a bit and thought I would chime in with a question. I like the idea of a $10k helicopter I can't help but think about the cost of the replacement batteries. If we are looking at 2.3 Kg of battery per minute of flight as Graviman suggested and we want to fly more than 10-15 minutes we would have to have a pretty good size battery pack I'm guessing. How many charge/discharge cycles are NiMH batteries good for before requiring replacement? It would really suck to have a $10K helicopter that flies for 30 minutes on every charge but you have to spend $100K on batteries after 10 flights! I'm sure it wouldn't be that bad but I figured I would bring it up and see what you all thought. I know most of this thread has been about how to make the thing fly and not how to make it practical but I think it is an added aspect to the challenge.
Max
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Max,
There are a number of people who are working toward producing an Ultralight electric recreational helicopter. The motivation appears to be the challenge, combined with the belief that electrical storage technology will see significant improvements over the next decade or two.
This is probably going to be a staged growth that parallels the electrical storage improvements. First the designer/developers. Then the hobbyists, who enjoy building, taking short test flights and discussing their craft. And finally, those who consider the flying as their primary interest.
IMHO, electric propulsion and control may well be a reincarnation of the exciting early days of helicopters.
Dave
There are a number of people who are working toward producing an Ultralight electric recreational helicopter. The motivation appears to be the challenge, combined with the belief that electrical storage technology will see significant improvements over the next decade or two.
This is probably going to be a staged growth that parallels the electrical storage improvements. First the designer/developers. Then the hobbyists, who enjoy building, taking short test flights and discussing their craft. And finally, those who consider the flying as their primary interest.
IMHO, electric propulsion and control may well be a reincarnation of the exciting early days of helicopters.
Dave