Can People Fly? Investigating Human Flight Possibilities

[AlephZero]

I tend to be on DaveC's side of this argument.

You need to be careful what you mean by "lifting work" here. Consider the case of hovering, since it's simple (no drag forces, etc).

To create the lift force, you have to add downwards momentum to the air. That's the whole story - Bernoulli's principle etc are just ways to explain HOW you might do it, not WHAT you have to do.

When you move the air downwards you give it KE, which is why you have to do work. For a mass m and velocity v the KE is (1/2)mv^2. For mass 2m and velocity v/2 the momentum is the same, but the KE is (1/4)mv^2 or half as much. In general, it's more efficient to move large of mass slowly, not a small mass quickly.

Having denser air is a good way to move more mass, so less power is reqired to generate the same lift.

BTW This argument also explains why helicopters have huge diameter rotors compared with aircraft propellors. The size of a propellor is limited by clearance of the ground and/or the airccraft body. A heli rotor can be as big as you like, and bigger means more efficient.

One other thing: russ-watters said "the lift required is the same therefore the torque on your shoulders is the same". That would be true if all the force from the wings was transmitted through your arms. However assuming you are going to fly in a horiziontal position you want the centre of lift over the center of mass which implies (to me) the wings attached to a harness to your torso, but powered somehow by the arms. So your arm muscles would be supplying the power, but not also supporting your full weight. That sounds like a better engineering solution to me.

 

[Panda]

Surely it is a question of power to weight. Thats why birds have very light weight bone structures.
Man powered flying machines have huge wing spans in order to create the lift of the man and the machine. Early macines failed because material technology didn't have light enough materials.
If you negate the weight of the wings and most of yourself by attaching a balloon say then your arms could provide sufficient lift to go up and down. Of course the drag of the balloon would make it difficult to move anywhere apart from where the wind wants to go.
The ideal solution would be a wing which contained sufficient gas to more than negate its own weight, but I doubt we have the materials for that.
Build one and enter it into a Birdman Competition

 

[FredGarvin]

BTW This argument also explains why helicopters have huge diameter rotors compared with aircraft propellors. The size of a propellor is limited by clearance of the ground and/or the airccraft body. A heli rotor can be as big as you like, and bigger means more efficient.

The main limiting factor is tip speed. You can go large to a point. Structural considerations also play a role.

As far as the power argument is concerned, it's one thing to look at energy, but thrust/lift for the flapping wing is based on transfer of momentum. So you are talking about a person having to accelerate a mass of air from V1 to V2 in a given amount of time. More dense air means a greater mass to accelerate with the same wing size.

 

[russ_watters]

I'll have to think about that first part, but...

One other thing: russ-watters said "the lift required is the same therefore the torque on your shoulders is the same". That would be true if all the force from the wings was transmitted through your arms. However assuming you are going to fly in a horiziontal position you want the centre of lift over the center of mass which implies (to me) the wings attached to a harness to your torso, but powered somehow by the arms. So your arm muscles would be supplying the power, but not also supporting your full weight. That sounds like a better engineering solution to me.

Yes, I was assuming you'd literally have wings attached to your arms. Having a harness and some sort of spring-loaded mechanism for supporting and flapping them could, at least, allow you to glide without expending energy.

 

[Ivan Seeking]

However, with denser air, the power needed to reach glide speed is increased, as is drag while gliding.

 

[Ivan Seeking]

As far as the power argument is concerned, it's one thing to look at energy, but thrust/lift for the flapping wing is based on transfer of momentum. So you are talking about a person having to accelerate a mass of air from V1 to V2 in a given amount of time. More dense air means a greater mass to accelerate with the same wing size.

Yes, I had to think about that one for a second.

Another way to see it is that based on the idea that AlephZero stated, it would take less work to lift an object as well.

 

[grant9076]

I do not have any Phd's. However, I hope that my 17+ years as a professional pilot can be helpful.

1. The most important element of flight (human or otherwise) is control. The flyer (human or otherwise) must have complete control about the pitch, roll and yaw axes from before launch to after landing. Unless you have a stability augmentation system, your aircraft needs to be both statically and dynamically stable about all three axes. Stability/Control was perhaps the most important problem solved by Otto Linienthal and by the Wright Brothers that made modern day aviation possible.

2. The only way to launch is to create or exploit a large surplus of energy (kinetic or potential). Conventional aircraft use high thrust settings for takeoff. Most birds and insects have to jump high enough to get the first wing beat while some (albatrosses) actually need a running start. Those that cannot run fast enough or jump high enough (swifts, bats, hang glider pilots) need to launch from elevated surfaces or be stranded on the ground.

3. Sustaining level flight requires a power source (internal or external) that can supply the power at or greater than minimum sink rate. For example although glider pilots don't have engines, they routinely log 3+ hour flight using thermals, ridge lift or wave lift.

4. Landing obviously requires a controlled energy loss to touchdown with the mimimum velocity normal to the landing surface (followed by further energy depletion if necessary).

5. For safety, there has to be multiple "layers of protection" from malfunctions or operator errors that could jeopardize safety. This requires properly designed and maintained equipment (even birds preen their feathers regularly). It also requires established normal and emergency proceedures that are supported by checklists as well as sound training to use them properly.

 

[Danger]

Nice post, Grant. There are a lot of pilots here, but you seem to have summed things up in a manner that most of us haven't over multiple responses in various threads.

 

[grant9076]

Thanks Danger. Even I occasionally have my moments. Also, in the section of my post about landings, after "landing surface" I should have added "unless you are a Navy pilot". By the way, I take it that you are a pilot too.

 

[Danger]

Not for 30+ years. :grumpy:
Got grounded on a medical before I hit 20. (Damned diabetes... which I don't have any more, but now it's too late. )

 

[sphoenixee]

Many many thanks to all for the posts. I'll be sure to share my experiences when I'm done.

sphoenixee

 

[DaveC426913]

(Damned diabetes... which I don't have any more, but now it's too late. )

You do realize that diabetes never goes away

 

[Danger]

It did in my case. My insulin production wasn't inoperative; it was delayed by a few hours, then I would go into a hypoglycemic loop. Apparently it straightened itself out, because I've been fine for about 15 years. I can eat whatever I want, whenever I want, and drink like a turbopump, and have no problems.

 

[marcusl]

That's pretty much it. Most of the relevant muscles are the same in birds as they are in humans, but while our leg muscles are many times larger than our chest and back muscles, for birds it is the opposite.

To the s phoenix: Birds have numerous other adaptations that you might want to make for yourself to increase your "flyability". Their special lungs are proportionally smaller yet more efficient than ours, while their flight muscles are richly endowed with blood vessels and myoglobin (the reddish "dark meat"). To lighten their bodies, many of their bones are hollow and their sexual organs shrink to a tiny size at all times except mating season.

Let us know how you do with these mods...

 

[FredGarvin]

You do realize that diabetes never goes away

Pregnancy induced diabetes does. Anything you want to tell us Danger?

 

[Danger]

Er... no... :uhh:

 

[sphoenixee]

I realize that many of you think this is a joke, but please realize that my project does involve far more than ornithopter flight. It's just that I had a question specifically about this part and wanted some input. So, if you don't have anything related or helpful to say, then please don't waste your time commenting or my time reading.

sphoenixee

 

[Danger]

No need to get snippy, youngster. You've had more than enough serious opinions from all of us. Despite the level of expertise of your various respondents, we still have to lighten up once in a while. We've already explained why you can't do what you want to, and yet you are insisting that we keep brainstorming until we come up with a way that you can. If any of us could overcome science enough to do that, we'd be rich.

 

[sphoenixee]

No need to get snippy, youngster. You've had more than enough serious opinions from all of us. Despite the level of expertise of your various respondents, we still have to lighten up once in a while. We've already explained why you can't do what you want to, and yet you are insisting that we keep brainstorming until we come up with a way that you can. If any of us could overcome science enough to do that, we'd be rich.

I'm a youngster now? You got an elixir? (Now, that'd make you rich...) I was being a bit harsh, yes, and my humblest apologies for that. I do appreciate and highly value your insightful comments. Nevertheless, I still don't appreciate ridiculing of my project or discussion of completely unrelated things, and, I did not and still do not insist that you do anything.

 

[tehno]

No comment

I realize that many of you think this is a joke, but please realize that my project does involve far more than ornithopter flight. It's just that I had a question specifically about this part and wanted some input. So, if you don't have anything related or helpful to say, then please don't waste your time commenting or my time reading.

sphoenixee

https://www.physicsforums.com/showthread.php?t=148806

 

[DaveC426913]

I'm a youngster now? You got an elixir? (Now, that'd make you rich...) I was being a bit harsh, yes, and my humblest apologies for that. I do appreciate and highly value your insightful comments. Nevertheless, I still don't appreciate ridiculing of my project or discussion of completely unrelated things, and, I did not and still do not insist that you do anything.

I don't recall anyone ridiculing anything. Worst offense was a side discussion about Danger's Magical Diabetes. My bad there.

 

[bowakowa]

My two cents.

I joined just to post this. I hope that maybe someone else has the wherewithal to execute what I yet cannot. What if you had essentially a biomimicked set of wings optimized for human weight, not unlike an articulated hang glider, but with some imitation of at least the feather stages to introduce vortex's at low speeds. Attach these to a rigid body harness holding the flyer in a prone position. Allow the flyer to apply force for the downstroke with a combined leg press/arm press. This allows most of the capacity for human work to be applied together. Implement either a sliding mount for the wing or lateral hinge mechanism front to aft of wing sweep that is tethered in some way to the stroke's position, keeping the center of weight in line with the center of lift of the wing. If more power is needed, affix some small dc motors akin to drill motors in line with the pulleys that drive the wing, giving power assist. Power these by replacing the skin of the wing with new mylar thin film photovoltaics. Use Lithium Ion batteries to store energy for takeoff. Now, find a spot with sufficient room for the wing to fully "flap", and take off. Using the power assist, attain enough altitude to find thermals and use them for maximum efficiency and rest, while of course still collecting solar energy to help you from thermal to thermal. Control the angle of attack of the wing by moving the handles on the end of a bar for and aft in a channel on a pivot. Pull this same bar in and away from the line of bilateral symmetry to extend and retract wings. I admit it is difficult to ascertain what I mean by the last two sentences, in summary I would simply refer to it as an integrated closed loop control system. Before writing me off as a kook, google the Argentinian Teratorn, also look up some solar gliders.

 

[eksurya]

I just started my research on this topic with some air propulsion theory behind

Have u got any progress made on this topic ...

 

[shelbygirl]

My daughter is actually researching this for a science fair project. She has read the "Maximum Ride" books by James Patterson and has become very interested in the idea of humans with wings. The topic of her science fair project is "Can people fly with wings?". This forum has been very informative. Any thoughts for how a 7th grader should proceed? I have had her research the anatomy of birds, bats, and humans. I have also had her look up the ration of weight vs wing span.

Any resources we should consider? thanks! Also - we are not sure what some of the symbols mean ("N" and "J"). My degrees are in Polictical Science and Economic Development, not science. :)

 

[russ_watters]

What is the goal of the project?

 

[Travis_King]

When you say "N" and "J" are they truly sybols or are they units? Like "Requires 500 N" and "The amount of energy requried is one million 'J' "

Or...For a 7th grader, it's kind of hard to do this topic justice. Maybe a study on the feasibility of past designs? There have been plenty of flying-man designs. I'm almost positive all non-gliders have failed, but I'm sure they had some good components to them. Study what worked and what didn't.

I.e. This one had a large wingspan but it was too heavy
This one had the right mechanisms but it was too hard for a person to operate

That kind of stuff.

 

[shelbygirl]

Thank you for the responses!

First - I was wondering what the symbols meant just as you wrote "500 J".

Second - I wish I could convince her to change the subject. She very much wants to know about actual human flight. She gets upset when she finds something telling her it is not possbile. I am having her write down all of the reasons why it is not possible so she might find and alternative.

This is her idea. Create some kind of "mind connection" to the attachable wings. Think of the "mind flex" toys and "Doc. Oct" from Spiderman. She has researched the use of brainwaves to move objects - mind flex. The limitation is that the user has to concentrate very much so in order to "move" the object. We also discussed how nerves work.

My thought was if she followed up on this idea, perhaps she could refine it enough to be applied elsewhere - ie allowing parapalegics the ablility to walk or allowing MS patients to use other parts of the brain to overcome damaged parts. (I have MS so she liked that idea)

I degress, What do you all think of the "mind connection" to attachable wings?

 

[shelbygirl]

please excuse the spelling

 

[Travis_King]

a "J" is a Joule. A unit of energy.
An "N" is a Newton, a unit of Force

Second. It's great to encourage out-side the box thinking. But I don't care how hard you concentrate, your mind alone isn't going to provide the energy requried to sustain powered flight...
But it is a science fair. A study of potential applications of this technology (I haven't heard of it...I don't think it is for actually "moving" things, but for providing the data for control, perhaps?) is probably a pretty good option.