Help Design a Human-Powered Helicopter

In summary: I don't know if ground effect would be significant with the slow-moving rotors of a human-powered helicopter. I've seen experiment results that show the effect dropping off quickly as the rotors move away from the ground (< 3m).Stability and control will be major issues, and I believe electronics are not allowed by the rules.And the problem is not impossible. We have better engineering tools than at any time in the past. We just have to take advantage of them.When they say 'human powered' - do they count 'human fuelled'?A gas turbine will run on bio-diesel !Looks like you are going to need Leonardo on this one.He's
  • #141
Phrak said:
"Cyclists", in plural, Cyrus. Say you have four blades and put the cyclists in the center of each blade. This means that the bending stress on the blades is cut in half. Belatedly, I recall (to first order, see Poison ratio) that the strain, that leads to coning, is also cut in half.

Did you just throw in a bunch of words together hoping it would make sense? Sorry, no.

The rules state that at least one member of the crew must face in the same direction throughout the flight. So this ...complicates things.

A bit of common sense(:rolleyes:) shows that the rules were intended to imply that the rotorcraft needs an anti-torque device. You can email the rules committee if you want clarification and post their reply here.
 
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  • #142
Cyrus said:
Did you just throw in a bunch of words together hoping it would make sense? Sorry, no.

no, I did not :frown:
 
  • #143
dual rotors (internally pressurized for strength) for inertial stability
double cone/roller drive assy.
I am working on sketches for an RC model

dr
 
  • #144
dr dodge said:
dual rotors (internally pressurized for strength) for inertial stability
double cone/roller drive assy.
I am working on sketches for an RC model

dr

What on Earth does that mean. Internal pressure does not change material properties. And the rotation of the blades will cause all the air to...(think about it).
 
  • #145
Phrak said:
Really, I'm not sure how this works out. Can you give details?

It's precisely as you noted: Volume and mass of an aicraft increase as the cube of a scaled length, as does the induced drag. However, their parasitic drag, which is most of the drag while at cruise, increases only as the square of a scaled length.

But there is still stress and strain to consider for human powered flight, in general.

Yes. However, all other factors being equal, you're more likely to be successful if you design it to be powers by eight cyclists than you are if it's designed to be powered by four, due to the cube-square issue, above.

Do you recall something called the Square-Cube rule, or square-cube law as applied to the strength of a bone or beam, or even a wing as it scales in length only? The idea is to keep material density unchanged, and the shapes of everything stay the same. It's just scaled up in size. Latently I found that the amazing Wikipedia provides it.

http://en.wikipedia.org/wiki/Square-cube_law" [Broken]

For Aerodynamic Forces:

"When a physical object maintains the same density and is scaled up, its mass is increased by the cube of the multiplier while its surface area only increases by the square of said multiplier. This would mean that when the larger version of the object is accelerated at the same rate as the original, more pressure would be exerted on the surface of the larger object."

As this applies to a wing, you're going to have higher wing loading with a scaled up version. This is why we can build scaled models of fighters that required steel and aluminum alloys while we can use balsa and plywood build a scaled R/C version that'll pull 20 Gs.

Under the hot summer midday sun, you might expect one horse power per square yard of solar insulation. The best Solar electric panels are about 15% efficient, I think...

Market leader's SunPower's panels conversion ratio is 19.3%. However, we're concerned less with electrical power output per square foot than we are with power per lb. The current world record is 41.6%, achieved on August 26, 2009. For thin-films, which are much lighter than crystalline, it's expected to range from 30% to more than 35% over the next decade.

Well, I did too, but no one took me seriously. It would significantly reduce the weight-per-pilot requirement of the airframe--by as much as 50%. But there's a catch. There must be at least one crew member that cannot rotate but face the same direction throughout the flight.

Yes, the pilot! Well, he can darn well pedal, too!

(BTW, very cool stuff you had on the crosswind landing thread.)

Thanks!
 
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  • #146
Cyrus said:
Internal pressure does not change material properties. And the rotation of the blades will cause all the air to...(think about it).

pressure does change the properties of a sealed container. take a piece of plastic tubing good to 200 psi. no positive pressure differential, its limp as a ...whatever
put 200 psi positive pressure, you can hold one end and it will stand erect. rocket tanks have no structural rigidity without positive pressure.

and do you think all the air will fly out to the ends?

dr
 
  • #147
dr dodge said:
pressure does change the properties of a sealed container. take a piece of plastic tubing good to 200 psi. no positive pressure differential, its limp as a ...whatever
put 200 psi positive pressure, you can hold one end and it will stand erect. rocket tanks have no structural rigidity without positive pressure.

and do you think all the air will fly out to the ends?

dr

My point was that it will change the rigidity of the structure, but not its strength. The strength is a material property inherent to the plastic. It will yield at some sigma stress value, air or no air.

As for the air going to the ends. Not "fly out", but it will "pile up" due to pressure gradient. There is going to be a radial acceleration. My friend is doing pneumatic trailing edge flap actuation on rotor blades and has this very problem. The centrifugal force is:

[tex]F_{cf}= \frac{M \Omega^2 R}{2}[/tex]​
 
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  • #148
the added rigidity would decrease the structure needed.
obviously it does not change the strength

this then potentially would allow less mass of the rotors.
as far as "pile up", are you saying that the rotation would significantly increase the pressure inside the rotor at the ends?

dr
 
  • #149
dr dodge said:
the added rigidity would decrease the structure needed.
obviously it does not change the strength

Perhaps, if you could resolve the centrifugal force problem. I suspect you would find the airfoil sections to be 'bulging' near the tips, and under inflated at the root.

this then potentially would allow less mass of the rotors.
as far as "pile up", are you saying that the rotation would significantly increase the pressure inside the rotor at the ends?

dr

It's certainly possible.
 
  • #150
Cyrus said:
It's certainly possible.

It's reality, and the fundamental basis behind radial-flow compressors.
 
  • #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
 
  • #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" :rofl:...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" :rofl:...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
 
<h2>1. How does a human-powered helicopter work?</h2><p>A human-powered helicopter works by converting the energy from human pedaling into rotational motion, which then powers the rotors to generate lift. The pilot pedals a series of gears and chains that are connected to the rotors, allowing them to spin and create lift.</p><h2>2. What materials are used to build a human-powered helicopter?</h2><p>The materials used to build a human-powered helicopter vary, but typically include lightweight materials such as carbon fiber, aluminum, and titanium. These materials are strong and durable, but also lightweight to reduce the overall weight of the helicopter and make it easier to fly with human power.</p><h2>3. How much weight can a human-powered helicopter lift?</h2><p>The amount of weight a human-powered helicopter can lift depends on various factors such as the design, materials used, and the strength and endurance of the pilot. The current record for the Sikorsky Prize, which requires a flight of at least 60 seconds and a height of 3 meters, is 198 pounds (90 kg).</p><h2>4. How long does it take to build a human-powered helicopter?</h2><p>The time it takes to build a human-powered helicopter varies, but it typically takes several months to a year to design, build, and test a functional prototype. This process involves a team of engineers, designers, and pilots working together to create a safe and efficient helicopter.</p><h2>5. What are the challenges of designing a human-powered helicopter?</h2><p>Designing a human-powered helicopter presents several challenges, including weight limitations, aerodynamics, and pilot endurance. The helicopter must be lightweight to be able to fly with human power, but also strong enough to withstand the forces of flight. The aerodynamics must be carefully considered to ensure efficient lift and control. Additionally, the pilot must have the strength and endurance to power the helicopter for an extended period of time.</p>

1. How does a human-powered helicopter work?

A human-powered helicopter works by converting the energy from human pedaling into rotational motion, which then powers the rotors to generate lift. The pilot pedals a series of gears and chains that are connected to the rotors, allowing them to spin and create lift.

2. What materials are used to build a human-powered helicopter?

The materials used to build a human-powered helicopter vary, but typically include lightweight materials such as carbon fiber, aluminum, and titanium. These materials are strong and durable, but also lightweight to reduce the overall weight of the helicopter and make it easier to fly with human power.

3. How much weight can a human-powered helicopter lift?

The amount of weight a human-powered helicopter can lift depends on various factors such as the design, materials used, and the strength and endurance of the pilot. The current record for the Sikorsky Prize, which requires a flight of at least 60 seconds and a height of 3 meters, is 198 pounds (90 kg).

4. How long does it take to build a human-powered helicopter?

The time it takes to build a human-powered helicopter varies, but it typically takes several months to a year to design, build, and test a functional prototype. This process involves a team of engineers, designers, and pilots working together to create a safe and efficient helicopter.

5. What are the challenges of designing a human-powered helicopter?

Designing a human-powered helicopter presents several challenges, including weight limitations, aerodynamics, and pilot endurance. The helicopter must be lightweight to be able to fly with human power, but also strong enough to withstand the forces of flight. The aerodynamics must be carefully considered to ensure efficient lift and control. Additionally, the pilot must have the strength and endurance to power the helicopter for an extended period of time.

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