A very little something different.
Thread Starter
Join Date: Apr 2003
Location: Vancouver, BC, Canada
Posts: 1,635
Likes: 0
Received 0 Likes
on
0 Posts
A very little something different.
An electric single seat helicopter with single-blade rotors and a side-by-side configuration.
Consider;
The future: Most would agree that billions of dollars are going to be spent developing and improving electric vehicles over the next few decades.
The problem: Electric batteries and motors are currently heavy and weight is a big big concern with rotorcraft.
A solution:
. ` . Use the most efficient lift to power rotor configuration there is ~ the side-by-side configuration.
. ` . Use the most efficient rotor count there is ~ single-blade rotors.
And there is more;
No counterweights; Use the electric motor in place of the wasteful counterweight, on each rotor.
Utilize gyroscopic precession: The gyroscopic precession within the spinning motor, as it circles its mast, will apply lift to lift the motor, thereby partially countering the lift of the blade on the opposite side of the mast.
And there is even more;
http://www.unicopter.com/ElectroRotor.html
This thread is for the interest of those who might be interested in something interesting, for discussion, and to place the ideas into the public domain.
Consider;
The future: Most would agree that billions of dollars are going to be spent developing and improving electric vehicles over the next few decades.
The problem: Electric batteries and motors are currently heavy and weight is a big big concern with rotorcraft.
A solution:
. ` . Use the most efficient lift to power rotor configuration there is ~ the side-by-side configuration.
. ` . Use the most efficient rotor count there is ~ single-blade rotors.
And there is more;
No counterweights; Use the electric motor in place of the wasteful counterweight, on each rotor.
Utilize gyroscopic precession: The gyroscopic precession within the spinning motor, as it circles its mast, will apply lift to lift the motor, thereby partially countering the lift of the blade on the opposite side of the mast.
And there is even more;
http://www.unicopter.com/ElectroRotor.html
This thread is for the interest of those who might be interested in something interesting, for discussion, and to place the ideas into the public domain.
Last edited by Dave_Jackson; 9th Sep 2006 at 20:34.
Join Date: Nov 2004
Location: Cambridgeshire, UK
Posts: 1,334
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
Dave, still not convinced (after some thought). The motor precession will generate a blade root reaction torque, but you would need to vary RPM for collective lift variation. Also the counter balance produces more drag than a second blade. Very high motor inertia could balance the forces/torques in theory though.
Motors offer excellent power to weight at high RPM, but the epicyclic reduction gearbox mass tends to be the limiting factor (mass always finally limited by torque requirement). Batteries are actually very good in terms of power to weight (if designed for high current), but fall down on energy to weight. My final year project was for the guy behind this:
http://www.intelligent-energy.com/in...821&artID=3682
Notice he uses a fuel cell for sustaining power generation, with batteries for take off and climb. I've flown the Dimona (not this one), and it does have a very good lift/drag (~30 from memory) so you only need a couple of kilowatts to sustain flight.
Helicopters consume high power all the time. The only way to justify a motor hybrid is to improve turbine power response, while keeping TET sensible. At some point there will be a breakthrough in fuel cells - might even be my designs that achieve it. In the mean time, the best development approach for energy/weight and power/weight in a light helicopter is multi stage boost turbo-diesel. Believe me there are enough problems to overcome (most of them financial) for this alone...
Mart
Motors offer excellent power to weight at high RPM, but the epicyclic reduction gearbox mass tends to be the limiting factor (mass always finally limited by torque requirement). Batteries are actually very good in terms of power to weight (if designed for high current), but fall down on energy to weight. My final year project was for the guy behind this:
http://www.intelligent-energy.com/in...821&artID=3682
Notice he uses a fuel cell for sustaining power generation, with batteries for take off and climb. I've flown the Dimona (not this one), and it does have a very good lift/drag (~30 from memory) so you only need a couple of kilowatts to sustain flight.
Helicopters consume high power all the time. The only way to justify a motor hybrid is to improve turbine power response, while keeping TET sensible. At some point there will be a breakthrough in fuel cells - might even be my designs that achieve it. In the mean time, the best development approach for energy/weight and power/weight in a light helicopter is multi stage boost turbo-diesel. Believe me there are enough problems to overcome (most of them financial) for this alone...
Mart
Last edited by Graviman; 12th Jan 2006 at 20:16.
Thread Starter
Join Date: Apr 2003
Location: Vancouver, BC, Canada
Posts: 1,635
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
Mart,
Never say never.
Seriously, thanks for submitting valid concerns. In response, and to pursue the pros and cons;
IMHO there are two basic concerns;
~ 1/ Improving the power to weight ratio of electric drives.
~ 2/ Optimizing the lift to weight ratio of the rotorcraft.
1/ The first concern is outside the domain of aeronautics. However, we know that significant improvements will be coming.
2/ The second concern is the domain of the rotary aerodynamists.
~ We know that inexpensive electric RC craft are being built today.
~ Is there any reason why an inexpensive full size homebuilt, with a long tether to a ground-based genset, cannot be built today?
~ Is there any reason why an inexpensive full size homebuilt craft, with a VERY short flight time, cannot be build today?
Consider that the flight time of all three can be improved, today, by adding the aerodynamic advantages of two independent rotors and single-bladed rotors.
A response to your concerns about the single-blade rotor;
Why? Look at the successful Bolkow rigid blades near the bottom of ; this web page
There is symmetry, however it is between lift and centrifugal force. See the 4th drawing in the middle of ; this web page
It appears that no one had tackled this serious problem, until recently See ; this web page
It will be done. And, what a cheap and fun project.
Keep the concerns coming.
Dave
Sorry Dave, but this ain't gonna happen.
Seriously, thanks for submitting valid concerns. In response, and to pursue the pros and cons;
IMHO there are two basic concerns;
~ 1/ Improving the power to weight ratio of electric drives.
~ 2/ Optimizing the lift to weight ratio of the rotorcraft.
1/ The first concern is outside the domain of aeronautics. However, we know that significant improvements will be coming.
2/ The second concern is the domain of the rotary aerodynamists.
~ We know that inexpensive electric RC craft are being built today.
~ Is there any reason why an inexpensive full size homebuilt, with a long tether to a ground-based genset, cannot be built today?
~ Is there any reason why an inexpensive full size homebuilt craft, with a VERY short flight time, cannot be build today?
Consider that the flight time of all three can be improved, today, by adding the aerodynamic advantages of two independent rotors and single-bladed rotors.
A response to your concerns about the single-blade rotor;
The bending moment input from the single blade will put mass way up.
You can't make it teetering 'cos there is no lift symmetry.
if the 1P lift doesn't shake it to bits first.
It will be done. And, what a cheap and fun project.
Keep the concerns coming.
Dave
Join Date: Nov 2004
Location: Cambridgeshire, UK
Posts: 1,334
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
Dave,
Too much danger of entanglement. I suspect the CAA/FAA would frown heavily on it.
Non. For short recreational flights it is quite doable. You would not be able to sustain flight long, and would have to plan to avoid autos over bad terrain. When the fun is over you have to recharge at 3kW (UK 240V 13A)
I still don't see why two independants are better than (say) a large main rotor with tail rotor, for the same ground box (or trailer). Coaxial is better suited, but really you only NEED counterrotation at mu>0.5.
Yeah, forget my original post - i was in a hurry since a feature on SpaceShipOne was starting. I hoped i had changed it before you read it. I just feel that there would be unecessary complications for no gain with the motor precession reacted single rotor.
The art of engineering is seeing the simplest solution to a problem, but engineers delight in complexity...
Mart
Is there any reason why an inexpensive full size homebuilt, with a long tether to a ground-based genset, cannot be built today?
Is there any reason why an inexpensive full size homebuilt craft, with a VERY short flight time, cannot be build today?
Consider that the flight time of all three can be improved, today, by adding the aerodynamic advantages of two independent rotors and single-bladed rotors.
There is symmetry, however it is between lift and centrifugal force.
The art of engineering is seeing the simplest solution to a problem, but engineers delight in complexity...
Mart
Last edited by Graviman; 12th Jan 2006 at 21:56.
Thread Starter
Join Date: Apr 2003
Location: Vancouver, BC, Canada
Posts: 1,635
Likes: 0
Received 0 Likes
on
0 Posts
Mart,
I still don't see why two independants are better than (say) a large main rotor with tail rotor, for the same ground box (or trailer).
Consider its use as a smaller UAV. It lands on some elevated location, folds its 'wings' and uses its cameras to observe the landscape. When require, it opens its 'wings' and fly to get a better view of the situation of interest. ~ Cheap and expendable.
Coaxial is better suited.
but really you only NEED counterrotation at mu>0.5.
Join Date: Jul 2003
Location: Port Townsend,WA. USA
Posts: 440
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
Dave,
Electric may be worth looking at, but according to Paul McCready, batteries have 100 times less energy per pound than gasoline. Thats the problem.
For just a few seconds of lift there might be a hybrid combination that would work. But its hard for me to see a weight advantage even for short term. I do not know where I could buy an electric motor and a battery capable of high discharge rate that would be less weight than a piston engine. Need to determine if the compressed air system has better energy density than electric, it would certainly be better for high power rate where batteries fail to provide.
slowrotor
Electric may be worth looking at, but according to Paul McCready, batteries have 100 times less energy per pound than gasoline. Thats the problem.
For just a few seconds of lift there might be a hybrid combination that would work. But its hard for me to see a weight advantage even for short term. I do not know where I could buy an electric motor and a battery capable of high discharge rate that would be less weight than a piston engine. Need to determine if the compressed air system has better energy density than electric, it would certainly be better for high power rate where batteries fail to provide.
slowrotor
Thread Starter
Join Date: Apr 2003
Location: Vancouver, BC, Canada
Posts: 1,635
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
Slowrotor,
You are absolutely correct.
There was no intent on my part to suggest that an electrical helicopter that can carry a person is practical today. Only that it is feasible today, and that it might be of interest to those who would enjoy the building, the short duration flight-testing, and the progressive improving of a craft; knowing that the project is at the threshold of significant electrical advancements.
Dave
You are absolutely correct.
There was no intent on my part to suggest that an electrical helicopter that can carry a person is practical today. Only that it is feasible today, and that it might be of interest to those who would enjoy the building, the short duration flight-testing, and the progressive improving of a craft; knowing that the project is at the threshold of significant electrical advancements.
Dave
Join Date: Nov 2004
Location: Cambridgeshire, UK
Posts: 1,334
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
Dave,
Part of that flight will involve finding a landing spot and having to make the judgement as to whether the machine can get in safely. Why compromise on the versatility? I don't see the gain for the extra drivetrain complexity.
Agreed that the mechanism is neat, but i just don't understand how that justifies the complexity. In the same overall machine size, coaxial will be way more efficient than two seperate rotors. Even a conventional tail rotor only wastes 5% power.
The only down side i know to coaxials is the rotor interference, which i imagine Sikorsky/Schweizer are looking at in great detail. This is why in the past i have always backed intermeshers (gyro stabilised outboard advancing). But you only need even consider this as retreating blade stall limits the flight envelope.
If twin rotors were the way to go, why are there so many threads arguing about the lack of payload capability of the V-22? You try to justify a single blade per rotor, then try to convince me that multiple rotors are better - i enjoy our discussions, but am genuinely puzzled by your stance on this.
It's actually very practical, using Li-MH power packs, and even compares favourably with turbine/Jet_A1 powered machines in terms of power/weight. You need to spin the motor at gas turbine RPMs, requireng smart use of materials and electronics. The range is almost non-existant, which is why most "energy recovery" schemes in the automotive world favour hybrids. Quite why (say) Honda and Toyota don't market hybrid diesels instead of hybrid gasoline is anyones guess - I get 50mpg, averaging 70mph over 455miles, in my VW Polo diesel...
Mart
It requires a lot of 'elbowroom' during flight.
Agreed that the mechanism is neat, but i just don't understand how that justifies the complexity. In the same overall machine size, coaxial will be way more efficient than two seperate rotors. Even a conventional tail rotor only wastes 5% power.
The only down side i know to coaxials is the rotor interference, which i imagine Sikorsky/Schweizer are looking at in great detail. This is why in the past i have always backed intermeshers (gyro stabilised outboard advancing). But you only need even consider this as retreating blade stall limits the flight envelope.
If twin rotors were the way to go, why are there so many threads arguing about the lack of payload capability of the V-22? You try to justify a single blade per rotor, then try to convince me that multiple rotors are better - i enjoy our discussions, but am genuinely puzzled by your stance on this.
There was no intent on my part to suggest that an electrical helicopter that can carry a person is practical today.
Mart
Last edited by Graviman; 15th Jan 2006 at 11:41.
Join Date: Feb 2005
Location: KPHL
Posts: 340
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
Dave, the lift and centrifugal forces don't cancel.
What you have labelled as the "pull" component of the "thrust" will create an imbalance between the opposing radial forces. Since that pull component will change with blade pitch angle, blade flapping motion, blade flapping angle, and blade azimuth the opposing forces will rarely be equal. You will be left with a very noticeable 1-per vibration and tremendous stress at the teetering hinge, mast, and on to the transmission. You will have to beef up your mast and teetering hinge to the extent that you'll lose the benefits of a teetering hinge.
Why not just add an opposing blade?
What you have labelled as the "pull" component of the "thrust" will create an imbalance between the opposing radial forces. Since that pull component will change with blade pitch angle, blade flapping motion, blade flapping angle, and blade azimuth the opposing forces will rarely be equal. You will be left with a very noticeable 1-per vibration and tremendous stress at the teetering hinge, mast, and on to the transmission. You will have to beef up your mast and teetering hinge to the extent that you'll lose the benefits of a teetering hinge.
Why not just add an opposing blade?
Join Date: Nov 2004
Location: Cambridgeshire, UK
Posts: 1,334
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
Matthew,
Don't forget that Dave's concept is to put the drive motor in the position of the counter weight. The reduction gearing will act as a gyro flywheel, creating a torque as the motor assy spins about the azimuth. Remember the little gyro on the model of the Eiffel tower in high school physics?
In practice the motor in this position would be aerodynamically draggy, and could not change RPM fast enough for the lift change required by a cyclic input. It is indeed complexity that is easilly overcome with a second (or ideally third) blade...
The best place for gyros is in the control system. I still much favour the Lockheed stability system, over Bell's horrible mixer system. Done right it converts the cyclic input from being a pitch/roll torque (or acceleration) control input to a pitch/roll velocity control input. The pilot will find this much more intuitive, instead of having to "balance on the ball" - especially in adverse conditions beyond his/her experience. The Bell system improves stability but reduces pilot control over what is still a pitch/roll acceleration input. The Lockheed system would have avoided many of the accidents seen over the years.
Mart
Don't forget that Dave's concept is to put the drive motor in the position of the counter weight. The reduction gearing will act as a gyro flywheel, creating a torque as the motor assy spins about the azimuth. Remember the little gyro on the model of the Eiffel tower in high school physics?
In practice the motor in this position would be aerodynamically draggy, and could not change RPM fast enough for the lift change required by a cyclic input. It is indeed complexity that is easilly overcome with a second (or ideally third) blade...
The best place for gyros is in the control system. I still much favour the Lockheed stability system, over Bell's horrible mixer system. Done right it converts the cyclic input from being a pitch/roll torque (or acceleration) control input to a pitch/roll velocity control input. The pilot will find this much more intuitive, instead of having to "balance on the ball" - especially in adverse conditions beyond his/her experience. The Bell system improves stability but reduces pilot control over what is still a pitch/roll acceleration input. The Lockheed system would have avoided many of the accidents seen over the years.
Mart
Last edited by Graviman; 14th Jan 2006 at 16:09.
Thread Starter
Join Date: Apr 2003
Location: Vancouver, BC, Canada
Posts: 1,635
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
graviman,
This thread is directed toward those who would have an interest in an electric helicopter that would be reasonably economical to build.
Every vehicle has its pros and cons. Yes the large 'elbowroom' is a con but the situation is no different from the Focke-Wulf http://avia.russian.ee/helicopters_eng/fw-61-r.html, when faced with the similar problem of heavy gasoline engines.
Mart are you a reincarnation of Lu? 
All of this has been discussed before. Please read up on 'Disk Loading'
______________________________
Mathew,
Too easy. 
Seriously, your argument about the 1P vibration is very valid. This is apparently the primary reason why few have played with the single-bladed rotor since Bolkow did.
My reason for regurgitating the concept is that one of (very few) friends has been intrigued by it since he built and flew a model single-bladed rotor in 1978. He has been talking up the idea for years. The (only) other friend is interested in helicopters and electric vehicles.
Therefore when I stumbled across the September 16, 2003 patent number 6619585, which covers a proposed means of minimizing this 1P vibration on a helicopter's single-blade rotor, an electric single-blade-rotor craft looked like a challenging, fun and cheap project to develop, build and play with.
_________________________________________
Graviman,
The intent is to speed up the rotor's reaction buy basing the pitch on torque not RPM.
Dave
This thread is directed toward those who would have an interest in an electric helicopter that would be reasonably economical to build.
Every vehicle has its pros and cons. Yes the large 'elbowroom' is a con but the situation is no different from the Focke-Wulf http://avia.russian.ee/helicopters_eng/fw-61-r.html, when faced with the similar problem of heavy gasoline engines.
"In the same overall machine size, coaxial will be way more efficient than two separate rotors."
"If twin rotors were the way to go, why are there so many threads arguing about the lack of payload capability of the V-22?"
"You try to justify a single blade per rotor, then try to convince me that multiple rotors are better."
"If twin rotors were the way to go, why are there so many threads arguing about the lack of payload capability of the V-22?"
"You try to justify a single blade per rotor, then try to convince me that multiple rotors are better."
All of this has been discussed before. Please read up on 'Disk Loading' ______________________________
Mathew,
"Why not just add an opposing blade?"
Seriously, your argument about the 1P vibration is very valid. This is apparently the primary reason why few have played with the single-bladed rotor since Bolkow did.
My reason for regurgitating the concept is that one of (very few) friends has been intrigued by it since he built and flew a model single-bladed rotor in 1978. He has been talking up the idea for years. The (only) other friend is interested in helicopters and electric vehicles.
Therefore when I stumbled across the September 16, 2003 patent number 6619585, which covers a proposed means of minimizing this 1P vibration on a helicopter's single-blade rotor, an electric single-blade-rotor craft looked like a challenging, fun and cheap project to develop, build and play with.
_________________________________________
Graviman,
"In practice the motor .... could not change RPM fast enough for the lift change required ...."
Dave
Join Date: Jul 2003
Location: Port Townsend,WA. USA
Posts: 440
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
Mart & Dave,
You could tether a power cord for an electric helicopter. In the early hang glider days, the unlicensed pilots got along with the FAA by dangling a rope, so they were considered to be manned kites. Tethered kites dont need a license. There may be a height limit, I dont know.
You could tether a power cord for an electric helicopter. In the early hang glider days, the unlicensed pilots got along with the FAA by dangling a rope, so they were considered to be manned kites. Tethered kites dont need a license. There may be a height limit, I dont know.
Thread Starter
Join Date: Apr 2003
Location: Vancouver, BC, Canada
Posts: 1,635
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
Al Hammer came up with this 'Been there, Done that' web page. 
In addition, a suggestion of his is also the basis for an unbelievably simple all electric joystick flight controller. For a description click here.
Please consider this method of rotorcraft flight control as being in the public domain.
In addition, a suggestion of his is also the basis for an unbelievably simple all electric joystick flight controller. For a description click here.
Please consider this method of rotorcraft flight control as being in the public domain.
Last edited by Dave_Jackson; 15th Jan 2006 at 06:39.
Join Date: Feb 2005
Location: KPHL
Posts: 340
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
Dave, I posted too quickly and left out one important observation. The lifting response of the motor only works when the rotor system is accelerated. If you're at a steady rpm then you will have a large lift force on the blade side, and no upwards force on the motor side. Small restoring forces will be created with the dynamics of the system, but I doubt if the magnitude will be sufficient to allow a level disk equilibrium, or even a convergent oscillation.
It might be worth creating equations of motion for this and then running simulations before going any further.
Matthew.
It might be worth creating equations of motion for this and then running simulations before going any further.
Matthew.
Join Date: Nov 2004
Location: Cambridgeshire, UK
Posts: 1,334
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
Dave, i've read about jet stream power generation before. I've even done some calcs, and it looks just as promising as ocean current generation. Might even help fuel that fleet of CO2 unfriendly helis! The real problem is the tether which has to allow the machine up to 40'000 ft. 8 miles of cable will not be light, so will need distributed helium balloons...
Doesn't need this, Matthew. The gyro rotating around the azimuth generates the torque to react the monoblade root. All lift generated by the monoblade.
Altering pitch (or RRPM) will vary the blade root bending moment. The only way to react this moment will be to vary gyro RPM. I can see how torque controlled pitch, with a variable RPM would work for collective input. This would not work for cyclic input, and is presumably the real reason for choosing an SBS tandem layout. For longitudinal control you will still generate 1P vibration, or are you planning a 3 or 4 rotor scheme?
If the single rotor is 141% the diameter of the twin rotor, it's disk loading is the same in a machine 71% the width. Single gearbox will, however, weigh 141% of combined twin gearboxes.
Mart
If you're at a steady rpm then you will have a large lift force on the blade side, and no upwards force on the motor side.
The intent is to speed up the rotor's reaction buy basing the pitch on torque not RPM.
All of this has been discussed before. Please read up on 'Disk Loading'
Mart
Last edited by Graviman; 15th Jan 2006 at 15:30.
Thread Starter
Join Date: Apr 2003
Location: Vancouver, BC, Canada
Posts: 1,635
Likes: 0
Received 0 Likes
on
0 Posts
Re: A very little something different.
Matthew,
Thanks for mentioning possible problems.
The idea is to have the blade's pitch set by the motor generated torque, not the rotor's rpm.
In addition, the idea is to have a blade that is even more rigid than the Bolkow blade. This will be easy to do, since the Bolkow blade was made of fiberglass and carbon is much less elastistic than fiberglass.
Assuming that this severally limits the blade's ability to bend in the out-of-plane direction, then any increase in the thrust of the blade will want to increase the teetering (flapping) angle at the root Picture #1 and Picture #2. This, in turn, through teetering linkage will move the blade's and the motor's center of gravity in the direction of the blade tip.
Hopefully, this off-center centrifugal force will counter the increased thrust of the blade, both vertically and horizontally.
Mart,
I don't fully understand your second to last question, Perhaps you are unaware that the centroids of the blade and motor shift off the center of the mast, both horizontally and vertically, as the blade root flaps upward and this shift is intended to offset the changes in the thrust of the blade.
As mention previously, think more about the interaction of the features that effect disk loading. For one example, think about the number of blades in your single rotor and what effect using 2 blades versis 4 blades (the same number as the 2 * 2 blades in the twin rotors) will have.
If you are going beyond the disk to talk about the transmission then you had better think about the effect of having a tail rotor, etc. etc, etc........
Dave
Thanks for mentioning possible problems.
The idea is to have the blade's pitch set by the motor generated torque, not the rotor's rpm.
In addition, the idea is to have a blade that is even more rigid than the Bolkow blade. This will be easy to do, since the Bolkow blade was made of fiberglass and carbon is much less elastistic than fiberglass.
Assuming that this severally limits the blade's ability to bend in the out-of-plane direction, then any increase in the thrust of the blade will want to increase the teetering (flapping) angle at the root Picture #1 and Picture #2. This, in turn, through teetering linkage will move the blade's and the motor's center of gravity in the direction of the blade tip.
Hopefully, this off-center centrifugal force will counter the increased thrust of the blade, both vertically and horizontally.
Mart,
I don't fully understand your second to last question, Perhaps you are unaware that the centroids of the blade and motor shift off the center of the mast, both horizontally and vertically, as the blade root flaps upward and this shift is intended to offset the changes in the thrust of the blade.
As mention previously, think more about the interaction of the features that effect disk loading. For one example, think about the number of blades in your single rotor and what effect using 2 blades versis 4 blades (the same number as the 2 * 2 blades in the twin rotors) will have.
If you are going beyond the disk to talk about the transmission then you had better think about the effect of having a tail rotor, etc. etc, etc........
Dave
Join Date: Nov 2004
Location: Cambridgeshire, UK
Posts: 1,334
Likes: 0
Received 0 Likes
on
0 Posts
I don't fully understand your second to last question, Perhaps you are unaware that the centroids of the blade and motor shift off the center of the mast...
For one example, think about the number of blades in your single rotor and what effect using 2 blades versis 4 blades will have.
If you are going beyond the disk to talk about the transmission then you had better think about the effect of having a tail rotor, etc. etc, etc........
Mart
Last edited by Graviman; 19th Jan 2006 at 00:46.
