Help Design a Human-Powered Helicopter

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A website has been launched to design a human-powered helicopter, seeking engineers to tackle this challenging project. Participants discuss the feasibility, noting that achieving sustained flight poses significant engineering hurdles, particularly regarding rotor efficiency and power output from human pedaling. The competition rules specify that the helicopter must take off and hover within a 10-meter square, which raises questions about rotor size and stability. Some participants express skepticism about the practicality of a human-powered helicopter, while others believe it could serve as a valuable educational project. Overall, the discussion emphasizes the need for innovative engineering solutions to overcome the obstacles presented by human-powered flight.
  • #151
that means potentially, as its rotation increases, if a check valve at the root allows only air in then the rotor will self compress the inside air charge, adding rigidity as RPM's increase.
If properly designed, this pressure increase could then changing its shape as speed increases.
this would allow it to "free spin" at slow speeds then change its shape when up to critical rotation
maybe this gas pressure could also be applied to control lateral movement

dr
 
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  • #152
dr dodge said:
that means potentially, as its rotation increases, if a check valve at the root allows only air in then the rotor will self compress the inside air charge, adding rigidity as RPM's increase.
If properly designed, this pressure increase could then changing its shape as speed increases.
this would allow it to "free spin" at slow speeds then change its shape when up to critical rotation
maybe this gas pressure could also be applied to control lateral movement

dr

This sounds too complicated. I don't think it will work. Why go trough all this trouble when you can just make it out of ribs, stringers and a spar? You need to do a feasibility study on this idea and flesh it out more.
 
  • #153
Agreed, Cyrus.

All squirrel-cage blowers found in central a/c and heating units throughout homes and businesses are radial-compressors.

Dr. Dodge: "this then potentially would allow less mass of the rotors"

Assuming the internal pressure would be enough to counteract that from the external airflow, then yes. However, I don't know if this is the case, and would have to run the calcs to be sure.

I suspect, however, that it will not be, and that you'll have to ensure a rigid structure with shrunk skin, much like monokote over balsa ribs for R/C aircraft (or doped silk used on WWI aircraft).
 
  • #154
mugaliens said:
Agreed, Cyrus.

All squirrel-cage blowers found in central a/c and heating units throughout homes and businesses are radial-compressors.

Dr. Dodge: "this then potentially would allow less mass of the rotors"

Assuming the internal pressure would be enough to counteract that from the external airflow, then yes. However, I don't know if this is the case, and would have to run the calcs to be sure.

I suspect, however, that it will not be, and that you'll have to ensure a rigid structure with shrunk skin, much like monokote over balsa ribs for R/C aircraft (or doped silk used on WWI aircraft).

when you talk of all this does it end up to energy storing devices which are illegal by the rules...according to me if the fixed wing was easily achieved why don't we just make these rotors just like a wing but not fixed i.e by incorporating an extended flap like trailing edge n with a built in pitch angle n make them coaxial blade settings this saves on weight n with efficient driving mechanism then we are definitely airborne rather than complicated mechanisms with more weight
 
  • #155
jeff kimathi said:
when you talk of all this does it end up to energy storing devices which are illegal by the rules...according to me if the fixed wing was easily achieved why don't we just make these rotors just like a wing but not fixed i.e by incorporating an extended flap like trailing edge n with a built in pitch angle n make them coaxial blade settings this saves on weight n with efficient driving mechanism then we are definitely airborne rather than complicated mechanisms with more weight

First and foremost, the fixed wing flight was not "easily achieved" by any stretch. But to your second comment, I fail to see the point of incorporating trailing edge flaps. You will have to justify this design, because doesn't make sense for this application. Moving on to a coaxial design, this will indeed save structural weight; however, and more importantly, it will be unstable (if you don't believe me, google the coaxial designs to see the common problem that plagued all of them). "then we are definitely airborne" :smile:...sure, whatever you say :wink:. Honestly though, stability of a coaxial is a poor, and the actuation lag time constants are high. In short, you save weight but gain significant stability and control problems.
 
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  • #156
if the design of the component does nothing but store energy, and nothing more, then it does IMHO violate the rules. I am not saying that, what I am saying is the flight has specific time goals, but if it takes 2 men (or women) 4 hours to bring the whole machine up to speed, then it is not an energy storage device. the idea is that you can only apply x amount of work/time so if you can not change the power you (as a person) can put out, then the only way to get the power you need is more time. because the counter rotating rotors are critical to the aircraft, and do the lifting once proper rotational speed is reached, they are not storing the energy, it is being used. The counter rotating rotors will add a natural "gyro stability" by not needing to offset the rotation with a tail rotor. You control the amount of lift by the amount of power you split between the two, but both are doing the work. simpler example: 2 dc electric motors connected together by their leads together. if you spin one, the other will turn. no energy storage. add a battery in between, charge it with one motor, and run the other. energy storage

dr
 
  • #157
dr dodge said:
if the design of the component does nothing but store energy, and nothing more, then it does IMHO violate the rules. I am not saying that, what I am saying is the flight has specific time goals, but if it takes 2 men (or women) 4 hours to bring the whole machine up to speed, then it is not an energy storage device. the idea is that you can only apply x amount of work/time so if you can not change the power you (as a person) can put out, then the only way to get the power you need is more time. because the counter rotating rotors are critical to the aircraft, and do the lifting once proper rotational speed is reached, they are not storing the energy, it is being used. The counter rotating rotors will add a natural "gyro stability" by not needing to offset the rotation with a tail rotor. You control the amount of lift by the amount of power you split between the two, but both are doing the work. simpler example: 2 dc electric motors connected together by their leads together. if you spin one, the other will turn. no energy storage. add a battery in between, charge it with one motor, and run the other. energy storage

dr

I think you should reconsider this statement in light of the extremely low rotor rpm. There is no such stability, as I stated previously.
 
  • #158
?
a little less cryptic response would sure help
action-reaction works the same regardless of rpm

dr
 
  • #159
dr dodge said:
?
a little less cryptic response would sure help
action-reaction works the same regardless of rpm

dr

The pole-zero structure of the open loop A stability matrix of the coaxial human powered helicopter at low RPM has right half plane poles. It is unstable, as was found out by the CalPoly HPH team, and the associated NASA TN.
 
  • #160
my discussion and input was mainly geared towards "energy storage"
but if coaxial rotors are so unstable, how come they work fine in rc toys?
much easier to fly than single rotor rc's

dr
 
  • #161
Cyrus said:
The pole-zero structure of the open loop A stability matrix of the coaxial human powered helicopter at low RPM has right half plane poles. It is unstable, as was found out by the CalPoly HPH team, and the associated NASA TN.
Several modern aircraft frames are inherently unstable, but made stable with computer controlled fly-by-wire in the loop. Is that a possibility here?
 
  • #162
dr dodge said:
my discussion and input was mainly geared towards "energy storage"
but if coaxial rotors are so unstable, how come they work fine in rc toys?
much easier to fly than single rotor rc's

dr

Because they spin much, much faster. When your HPH rotors are spinning 12-15 rpm, good luck getting gyroscopic anything.
 
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  • #163
mheslep said:
Several modern aircraft frames are inherently unstable, but made stable with computer controlled fly-by-wire in the loop. Is that a possibility here?

They tried it, but to no avail. The problem is that things happen so slow by the time you move your control surface, the blade has already rotated significantly before the blades move in response. So you are always 'behind the power curve' - so to speak.

Coaxials are the best in terms of reduced structural weight, but they are like trying to balance an upside down broom by its handle. If you can figure out stability, you will have a significantly lighter vehicle. Or you can go the quad rotor route as the Japanese did, but now you have huge structural weights. There is no easy answer. Do you want to try to make really light weight structures (that's not easy), or can you come up with a clever control scheme (that's not easy either)? Either choice has significant challenges.
 
  • #165
I am impressed by the feat of engineering, but god, what of the fail-safe? You get off the ground, and presumably your "out" is a parachute, but there is a large range in which it will not deploy in time. This seems... odd.

I suppose you could spend a few hours spinning up a flywheel, but that is dangerous too if you're sitting near it. I would much rather consider dirigibles for human powered flight.
 
  • #166
It's not legal to have flywheels, or to spin up rotors before hand, as per the rules. As for a parachute, why would you need one at 10 feet (if you run the numbers, you'll find that a person can't fly any higher than that)? There is no danger in those spinning rotors, because they max at around 20-25 rpm.
 
  • #167
Cyrus said:
It's not legal to have flywheels, or to spin up rotors before hand, as per the rules. As for a parachute, why would you need one at 10 feet (if you run the numbers, you'll find that a person can't fly any higher than that)? There is no danger in those spinning rotors, because they max at around 20-25 rpm.

Falling from 10 feet can be unpleasant, or lethal depending on your landing. My point is that a parachute requires a couple thousand feet to fully deploy, but you can shatter wrists, ankles, or your neck from 10 feet. The rotors I understand play no role in the danger. I did not remember the flywheel portion.

I'm not saying that this is some terrible risk, but falling 10 feet and not being hurt requires luck, or preparation and control in the fall. I just don't see the point of removing energy storage in some form, even though I know the rules are the rules.
 
  • #168
IcedEcliptic said:
Falling from 10 feet can be unpleasant, or lethal depending on your landing. My point is that a parachute requires a couple thousand feet to fully deploy, but you can shatter wrists, ankles, or your neck from 10 feet. The rotors I understand play no role in the danger. I did not remember the flywheel portion.

I'm not saying that this is some terrible risk, but falling 10 feet and not being hurt requires luck, or preparation and control in the fall. I just don't see the point of removing energy storage in some form, even though I know the rules are the rules.

Sure, falling from 10 feet would not be pleasant: but no risk no reward :wink:. As for the energy storage, that's because the rules are so that one designs a good vehicle. Storing energy would be a cop-out.
 
  • #169
Cyrus said:
Sure, falling from 10 feet would not be pleasant: but no risk no reward :wink:. As for the energy storage, that's because the rules are so that one designs a good vehicle. Storing energy would be a cop-out.

True, people take greater risks for lesser ends. Thanks for clarifying things!
 
  • #170
dr dodge said:
my discussion and input was mainly geared towards "energy storage"
but if coaxial rotors are so unstable, how come they work fine in rc toys?
much easier to fly than single rotor rc's

dr

that exactly my question to the guy who dismissed my idea of coaxial rotors...but looking at stability part and the weight saved plus the efficiency of having two sets of blades which increases the solidity i think coaxial would save tha day since by the rules there is provision for not more than two guys who would help support the machine...
 
  • #171
Cyrus said:
First and foremost, the fixed wing flight was not "easily achieved" by any stretch. But to your second comment, I fail to see the point of incorporating trailing edge flaps. You will have to justify this design, because doesn't make sense for this application. Moving on to a coaxial design, this will indeed save structural weight; however, and more importantly, it will be unstable (if you don't believe me, google the coaxial designs to see the common problem that plagued all of them). "then we are definitely airborne" :smile:...sure, whatever you say :wink:. Honestly though, stability of a coaxial is a poor, and the actuation lag time constants are high. In short, you save weight but gain significant stability and control problems.

i never said 'a trailing edge flap' what i tried to put across was on the design of the blades as in we all know flaps are used at low speeds n increase the lift drag ratio at a certain predetermined settings so basically i thought according to ma research on former designs n with fact that we're rotating the blades at low speeds why don't we then as we design the ribs include a slight angle drop of the rear point of ribs they are not flaps but at aerodynamic point of view with final assembly of this rotor with these ribs they increase the angle onto which we meet RAF...on coaxial part i just goggled as u advised n surely stability was not that great problem...thank u
 
  • #172
jeff kimathi said:
i never said 'a trailing edge flap' what i tried to put across was on the design of the blades as in we all know flaps are used at low speeds n increase the lift drag ratio at a certain predetermined settings so basically i thought according to ma research on former designs n with fact that we're rotating the blades at low speeds why don't we then as we design the ribs include a slight angle drop of the rear point of ribs they are not flaps but at aerodynamic point of view with final assembly of this rotor with these ribs they increase the angle onto which we meet RAF...on coaxial part i just goggled as u advised n surely stability was not that great problem...thank u

What did you read from your search that ignored the instabilities introduced by coaxial rotors?! I did the same thing, and was led to the opposite conclusion, over and over. To correct the instability requires... wait for it... more WEIGHT in the form of stabilizing surfaces or the means to control them.
 
  • #173
jeff kimathi said:
i never said 'a trailing edge flap' what i tried to put across was on the design of the blades as in we all know flaps are used at low speeds n increase the lift drag ratio at a certain predetermined settings so basically i thought according to ma research on former designs n with fact that we're rotating the blades at low speeds why don't we then as we design the ribs include a slight angle drop of the rear point of ribs they are not flaps but at aerodynamic point of view with final assembly of this rotor with these ribs they increase the angle onto which we meet RAF...on coaxial part i just goggled as u advised n surely stability was not that great problem...thank u

I'm having a hard time understanding what you write in your posts, can you avoid using text-speak. As for stability, look at the NASA TM I provided you.
 
  • #174
IcedEcliptic said:
What did you read from your search that ignored the instabilities introduced by coaxial rotors?! I did the same thing, and was led to the opposite conclusion, over and over. To correct the instability requires... wait for it...more WEIGHT in the form ofabilizing surfaces or the means to control them.


yeah that way i agree with u coz we need balance weights like in the case of rc types...and that makes it odd too but there are odds on every principle...
 
  • #175
Cyrus said:
I'm having a hard time understanding what you write in your posts, can you avoid using text-speak. As for stability, look at the NASA TM I provided you.

hey sorry never noticed my text-speak was just trying to explain ma unverified ideas.currently am working on a design model of both the rotor and coaxial design maybe when am through will email you the details...thanks for the NASA TM i got some mean full points
 
  • #176
Nice post...Thank you very much!...[PLAIN]http://parkservice-flieger.de/Icons/smileycool.ico
 
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  • #177
Cyrus said:
Because they spin much, much faster. When your HPH rotors are spinning 12-15 rpm, good luck getting gyroscopic anything.

Instead of using coaxial rotors, how about using counter-rotating rotors offset at opposite ends of a support boom? Would that be more stable? I would think it would have the same degree of stability/instability, but it actually make it more larger than is required, as well as more unwieldly, resulting in additional handling problems.

I know a good deal about airplane flight stability, but little about helo stability, even though I've flown two of 'em (not licensed - just fun rides). I'm having a difficult time picturing the instability part. Yes, technically counter-rotating rotors, whether coaxial or offset tend to counter gyroscopic forces. I get that part. But zero stability doesn't equate with negative stability i.e. it's not like flipping itself over is a more stable position than remaining in one position. Broomsticks balanced upside down on one's hand are dynamically unstable, yet kids manage to do it all the time, and the response rate required to stabilize that small of an object is much more rapid than for a human-powered helo with 30 feet of blade.

My thought towards what might be the best way to control the rotors is to use spoilers, not ailerons. Obviously, using a centralized blade-angling approach (http://en.wikipedia.org/wiki/Swashplate_(helicopter)" ) for such large, slow-moving rotors is probably a poorer approach than controlling the lift of the blades more directly, through ailerons.
 
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  • #178
is there any simple approach on to getting the leading edge radius of an airfoil model of say chord of 45cm and maximum thickness of 8cm with the point of max thickness being 1/4 of chord:confused :
 
  • #179
jeff kimathi said:
is there any simple approach on to getting the leading edge radius of an airfoil model of say chord of 45cm and maximum thickness of 8cm with the point of max thickness being 1/4 of chord:confused :

I'm sorry, but you're going to have to specify which of the many thousands of fully-wind-tunnel-tested airfoils you're talking about.

If you're proposing your own, then you're on your own.
 
  • #180
FYI: the cat is now out of the bag so enjoy



I was on briefly on the team early on but had to stop to finish my research and graduate: in any event, these guys and gals are working hard at it, so keep your fingers crossed for them.
 
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  • #181
Cyrus said:
FYI: the cat is now out of the bag so enjoy



I was on briefly on the team early on but had to stop to finish my research and graduate: in any event, these guys and gals are working hard at it, so keep your fingers crossed for them.


congratulations on your graduation...so what's new in you 4 us
 
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  • #182
The stability issue is an aerodynamic one. As the NASA-TM states the basic reason for the instability in the human powered helicopter is the high lock number of the blades. For those unfamiliar with this term and without getting unnecessarily technical, the lock number is basically the ratio of aerodynamic forces acting on the blade compared to the inertial forces acting on the blade.

Lock number = Aerodynamic Forces/Inertial forces

So it make sense that the low rotational speed, light weight blade and large blade area combination make for a very high lock number.

The inertial forces acting on a blade are stabilizing, just like a gyro, as per Newton's first law. The Aerodynamic forces are a little more complicated, but basically they make the helicopter and rotor unstable. The aerodynamics actually cause a combination of both positive and negative stability at different times but overall the result is undesireable and unstable. So with a high lock number the aerodynamic forces have a larger impact on the stability which means a less stable rotor.

Watch the following video starting at 4:30 to see some good examples of the stability issues of a helicopter rotor. I would suggest that the stability issue is just as solvable today in a human powered helicoper as it was in the 1940s in this model that eventually became the Bell 47, whether coaxial or not.

Also the little coaxial models that are very stable in a hover are not stable just because they have a higher RPM and lower blade lock numbers. They are stable because they have a weighted stabilizer bar that acts as a gyro and generates aerodynamic control inputs to a rotor that would other wise be unstable just like the model in the video below.

fast forward to 4:30
https://www.youtube.com/watch?v=uir9Engj4v4
 
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  • #183
Cyrus said:
Refer to 1:50-2:05 minutes into the video.



Compare to the Gossamer Albatross

Empty weight: 32 kg (70 lb)
Loaded weight: 97.5 kg (215 lb)​

This guy expects the craft to mass about 1500 kilograms gross as opposed to 97. I guess they're thinking solidly inside the box.
 
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  • #184
This guy expects the craft to mass about 1500 kilograms gross as opposed to 97. I guess they're thinking solidly inside the box.

Phrak,

I think he meant that for an airplane you only need to create a thrust of about 1/15 of the weight of the aircraft in order to achieve flight but with a helicopter you have to create a thrust equal to the weight of the aircraft. That would be 15 times more thrust to hover a helicopter than to fly an airplane.
 
  • #185
helisphere said:
Phrak,

I think he meant that for an airplane you only need to create a thrust of about 1/15 of the weight of the aircraft in order to achieve flight but with a helicopter you have to create a thrust equal to the weight of the aircraft. That would be 15 times more thrust to hover a helicopter than to fly an airplane.

Good thinking. That might be it, assuming a nominal L/D of about 6 to 1.

but I'd still give you ten to one odds UMD fails if the video is any indication of their design paradigm.
 
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  • #186
helisphere said:
...

Watch the following video starting at 4:30 to see some good examples of the stability issues of a helicopter rotor. I would suggest that the stability issue is just as solvable today in a human powered helicopter...
Is it? Lowering the lock number likely means adding mass to the blades - something the human powered helo can ill afford.

Thanks for the video. The demand by the executive suit to pilot the prototype leading to predictable disaster shows that the suits weren't any different back then. It's amazing the suit only suffered a broken arm.
 
  • #187
This, http://vtol.org/awards/HPHCBooklet.pdf" .

I draw your attention to the sketches pages 44 and 48 of http://vtol.org/awards/HPHCBooklet.pdf" as counted in .pdf pages.

Is this not a viable design method?
 
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  • #188
mheslep,

My point was that the model in the video was also unstable but they made it stable and they didn't do it by lowering the lock number. They took a stable reference and made the blades fly to it.

Phrak,

Yes I think that is probably the best way to go. The problem with big slow rotors is little centrifugal force to keep the coning and bending moments down. Those designs distribute weight more evenly.
 
  • #189
IcedEcliptic said:
I am impressed by the feat of engineering, but god, what of the fail-safe? You get off the ground, and presumably your "out" is a parachute, but there is a large range in which it will not deploy in time. This seems... odd.

I suppose you could spend a few hours spinning up a flywheel, but that is dangerous too if you're sitting near it. I would much rather consider dirigibles for human powered flight.

Fly off a dock on a calm day...get it as high as possible, when tired...let off a little...then descend with a little auto rotation and dump in the lake. Fish it out with a boat and find the tag line, attached before lift off, with a tennis ball.

But don't make the frame out of balsa wood, need aluminum for the frame and plastic or carbon fiber for the props...
 
  • #190
mgb_phys said:
When they say 'human powered' - do they count 'human fuelled'?
A gas turbine will run on bio-diesel !


Eat only beans for three days before, hook up a gas powered rocket engine under the seat, get the rotors going as a distraction, then ...ignition!...if only they had smileys here!
 
  • #191
PedalPower said:
Eat only beans for three days before, hook up a gas powered rocket engine under the seat, get the rotors going as a distraction, then ...ignition!...if only they had smileys here!

They do:

:biggrin: :blushing: :-p :rolleyes: ...
 
  • #192
helisphere said:
Phrak,

Yes I think that is probably the best way to go. The problem with big slow rotors is little centrifugal force to keep the coning and bending moments down. Those designs distribute weight more evenly.

We see these hopeful engineering teams taking the same dead end road. I'm perplexed as to why this seemingly obvious solution hasn't been tried.

A ten meter square target is not easy to hover over with a large machine, say 100 to 200 meter diameter, but this should be easily solved with software sending information from the pilot to those providing the peddle power and adjusting control surfaces.
 
  • #193
Thank you for your reassurance...my experience is generally restricted with structural and mechanical engineering skills and the advanced calculus was never mastered by me as far as aerodynamics are concerned.

Eventually we can run a test on the foil shape and the props surface areas/angle of attack to find the optimal rotation speed required to hover for 45 seconds, then lift to the height required...we honestly see the potential, but with so many attempts, the school based design teams were left with advancing the previous vehicles and trying to make their "hovercraft" sustain flight...we have had success reinventing the Pedicab, the modern rickshaw, and are now moving onto the entry for the vehicle design summit this summer at MIT. With this engineering as a background we are able to achieve a greater advantage over other riders and gain the momentum to get going on this project.

We are hoping that the rotor speed will be accelerated from the internal hub gear we are including in the drive train, allowing us to get it up to speed on a gradient scale through gears 1-4, by fifth we hope to be at a 1-1 ratio with the internal hub, and will have generated 8.94 full rotations for every rotation of the main pedal powered wheel, if one rotation per second (definitely possible) is maintained, then we will have created a rotor with 40 sq ft of surface area traveling at 535 RPM's, far more than is needed to attain lift of a regular sized helicopter that usually runs at 400-460 RPM's and weighs a ton.

Although the rotors on a regular heli are also able to produce lift from adjusting the angle, we have a fixed angle of 2% that we feel will be enough to allow for the slipstream effect to be more fluid with less drag and still create lift, and direct the trailing edges' airflow directly into the main lift producing area of the next blade, after the vacuum has collapsed upon itself and returned to it's original density...by generating more momentum, and creating the final rotor rpm to sustain, with at least three gears left to get off to a higher altitude, there is no way we can lose.

Would you be interested in handling the advanced calculations as a co-conspirator/awardee? We are merely looking for scientific calculations to back up our design, so we can obtain sponsorship with endorsements, to make the process go smoother.
 
  • #194
PedalPower said:
Would you be interested in handling the advanced calculations as a co-conspirator/awardee? We are merely looking for scientific calculations to back up our design, so we can obtain sponsorship with endorsements, to make the process go smoother.

All the calculations and explanations regarding power are shown previously.

If you read back, you will see that a human being cannot, for a long enough period of time, provide enough power to generate the required lift. Making everything you wrote above irrelevant.

I'd also note that no one here will do the work for you - as previously, the calcs are a few pages back showing the power issues.
 
  • #195
535 rotor RPM? You don't say what your rotor diameter is but let's say that it's only 25 ft in diameter. That would give you a tip velocity of 535*2*pi*12.5/60 = 700 feet/sec. Typical helicopters don't use tip speeds any faster than this because of sonic compressibility effects and if your rotor were any bigger in diameter it would have a faster tip speed at that RPM. Let's say 40ft dia: 535*2*pi*20/60 = 1120 feet/sec This is Mach one!

In order for a 25 foot rotor to lift 200lbs: horsepower = sqrt(T^3/2*rho*A)/550 = 3.36 hp and this momentum theory calculation is for an IDEAL rotor which is not even possible to make.

And a 40 ft dia rotor: 2.10 hp

Testing shows a strong athlete can only make 0.7 to 0.8 hp
 
  • #196
PedalPower,

Don't let me or anyone else discourage you. If this is something you really want to do then do your homework, find the answers and go for it! I'm not trying to smash anyone's dream, reality has a way of doing that on its own. I'm not your enemy, Love us, hate us, learn from us, I wish you the best, but it does seem there are a few things you don't understand about helicopters, especially the human powered type, but that doesn't have to be anything but temporary...
 
  • #197
helisphere said:
535 rotor RPM?

Lets say 40ft dia: 535*2*pi*20/60 = 1120 feet/sec This is Mach one!

In order for a 25 foot rotor to lift 200lbs: horsepower = sqrt(T^3/2*rho*A)/550 = 3.36 hp and this momentum theory calculation is for an IDEAL rotor which is not even possible to make.

Testing shows a strong athlete can only make 0.7 to 0.8 hp

Maybe we should design it like this ... http://www.clydecaldwell.com/photos/sandiego01/time_machine2.html
 
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  • #198
EDIT: Link correction noted.

What does that design have to do with the human powered helicopter? That's a time machine.
 
  • #199
jarednjames said:
All the calculations and explanations regarding power are shown previously.

If you read back, you will see that a human being cannot, for a long enough period of time, provide enough power to generate the required lift. Making everything you wrote above irrelevant.

I'd also note that no one here will do the work for you - as previously, the calcs are a few pages back showing the power issues.

That's funny you say that cause there are numerous pictures of guys "doing it" and also videos, as well as a couple of really heavy looking ones created by the engineers of other helicopter companies, they ended up facing tragic endings before they tried to take off...these were placed on display in the many aerospace museums, and I have even seen a couple as a student on field trips to DC.

Try speaking for yourself...others have interest, and you don't.
 
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  • #200
PedalPower said:
That's funny you say that cause there are numerous pictures of guys "doing it" and also videos, as well as a couple of really heavy looking ones created by the engineers of other helicopter companies,

Please do show us these pictures and videos - especially those that fall within the rules of this challenge. The davinci III is the only one of note so far and it's not even close to within the challenge rules.
they ended up facing tragic endings before they tried to take off...these were placed on display in the many aerospace museums, and I have even seen a couple as a student on field trips to DC

They faced tragic endings before taking off? As in they were destroyed trying to take off? That means they didn't work.

Again, as per the posts above, they show you HP required and HP possible.
 
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