Human Flight

[sphoenixee]

Stupid question: can people fly? Evidently, one doesn't see people flying around the streets, but is it possible? Has anyone done studies on whether this is possible or not? Any articles on this would be highly appreciated. Has anyone actually done this?

Furthermore, how does physics apply to this? My rudimentary knowledge estimates roughly 800 N is needed for a 70 kg person to fly. Supposing one wanted to fly for 1 km, then this would be 800 000 J or 191 kC. And if one wanted to cover that 1 km in say 3 min, that'd be 64 kC/min, which is 3800 kC/hr, which is a hell of a lot. I believe that fast running takes about 1000 kC/hr. Then again, it'd still be a miracle if one could just fly 100 m. Please correct my physics if I'm wrong. In any case, how viable is this sort of calorie output for small amounts of time (e.g. 30 secs, a few minutes).

I would appreciate extremely any articles on studies done regarding this, and also if it's viable at all.

Thanks,

~sphoenixee~

[russ_watters]

I'm not sure if this is what you mean, but this is pretty much it for human powered flight: http://www.progressiveengineer.com/PEWebBackissues2003/PEWeb%2042%20Sep%2003-2/MacC.htm

[sphoenixee]

Thanks, russ_watters.

Mmmm....that's really cool. So it has been done before, though he was sort of cheating with that bicycle stuff. Has anyone flown just with arms and legs plus wings (no bicycles, metal rods, gears, etc.) i.e. like Daedalus and Icarus of legend? Any further articles regarding the topic would also be highly appreciated.

[Averagesupernova]

Thanks, russ_watters.

Has anyone flown just with arms and legs plus wings (no bicycles, metal rods, gears, etc.) i.e. like Daedalus and Icarus of legend?

Why don't you try it and let us know how it turns out? :rofl: I'm sorry, I couldn't resist. I remember reading the thing about pedaling across the Channel years ago. I'm not aware of anyone who has flown by strapping wings on. Just hang gliders.

[sphoenixee]

Actually...maybe I will try it...whether it succeeds or not is another story. This is one of the things I'm thinking of doing for my research project this year.

Can someone give a physics analysis of this? i.e. how much energy and power it would take to maintain flight.

[Cyrus]

Research project for which class?

[carp]

you need more than physics, you also would need to know a little something about biology. If you are referring to a human using his arms to flap a pair of wings, forget about it. The physics part would require a lift greater than 700 N for a human to reach flight. However, biologically, no human on earth could flap that hard or fast. I saw somewhere that if birds were of compariable size to humans, they could outrun a ferrari and benchpress thousands of pounds.

Using human powered mechanisms is possible (duh). That is where aero engineering is born. If humans were somehow able to fly by themselves, why would the Wright brothers have even bothered?

carp
http://PropulsionAccess.com

[sphoenixee]

Research project for science/engineering fair.

Thanks for the info, carp. Which article did you get those bird facts from? Also, how much power exactly can the human body output via arms, legs, etc.?

As for the Wright brothers, flapping arms takes a lot more energy than sitting in a plane ;)

[selfAdjoint]

Research project for science/engineering fair.

Thanks for the info, carp. Which article did you get those bird facts from? Also, how much power exactly can the human body output via arms, legs, etc.?

As for the Wright brothers, flapping arms takes a lot more energy than sitting in a plane ;)


The reason for "that bicycle thing" is that our human legs are much stronger than our arms. and when the dinosaur ancestor of the birds started to evolve wings, they couldn't use them to fly either, but they could run very fast and use the proto-wings as stabilizers. So learning a little biology wouldn't hurt you.

You might also see if you can find an online video of the famous newsreel compilation of failed human flight experiments in the early twentieth century.

[sphoenixee]

selfAdjoint, that's rather evident that legs are stronger than arms in humans; more common sense than biology (I never actually learned that in biology). My point wasn't to not use legs; it was to not use bicycles. It's, well, much more idealistic to fly without using bicycles, i.e. by flapping your arms/legs.

Mmmmm....it seems somewhat decided that one cannot fly using human power without bicycles...if anyone has anything to the contrary, I'd be really interested. Thanks for all the replies.

~sphoenixee~

[russ_watters]

TMmmm....that's really cool. So it has been done before, though he was sort of cheating with that bicycle stuff. Has anyone flown just with arms and legs plus wings (no bicycles, metal rods, gears, etc.) i.e. like Daedalus and Icarus of legend? Any further articles regarding the topic would also be highly appreciated. No, it isn't possible for a human to propel him/herself efficiently enough by flapping wings.

[DaveC426913]

Has anyone flown just with arms and legs plus wings (no bicycles, metal rods, gears, etc.)
Yes. History is dotted with many ambitious entrepreneurs who have successfully flown for short distances of a few dozen to a few hundred yards.

Unfortunately, while none of the methods has succeeded in the Holy Grail of human flight: horizontal flight, all of them have succeeded extremely well with the rather easier component of vertical flight.

A mystery remains why history does not recount any subsequent attempts of any of these fliers.

:biggrin:

[Cyrus]

I think you should look into a different topic. Maybe something like measuring the drag on bodies.

Your premise for this project is fundamentally wrong and will result in a F.

[imperium2600]

without gene splicing, anabolic steroids, cybernetic implants, or rocket thrust caliber flatulance, a human has no chance of flying on their own. All you can hope for is finding a way to fall a little slower than every other roof jumper before you.

[Danger]

rocket thrust caliber flatulance

Forget that, too. After 16 or 17 beers and a load of nachos last night, I managed to alienate everyone in the bar... but I still couldn't get off the ground. :grumpy:
Maybe a worthwhile project would be to explain why humans can't fly without mechanical aid. I'd suggest starting with body density and relative muscle mass.

[Mech_Engineer]

Has anyone flown just with arms and legs plus wings (no bicycles, metal rods, gears, etc.) i.e. like Daedalus and Icarus of legend?

Make sure and take video when and if you try, I suspect it would be quite hillarious to watch :rofl:

[AlephZero]

Maybe a worthwhile project would be to explain why humans can't fly without mechanical aid. I'd suggest starting with body density and relative muscle mass.

I don't think its anything to do with body density and muscle mass. If those were the problem, we wouldn't be able to fly WITH mechanical aid because we couldn't generate enough power.

The obvious problem is geometry. Human bodies don't have any parts that can work as a wing.

For comparison, the heaviest bird which regularly flies long distances (i.e. several kilometers without stopping) is the Mute Swan, with a typical mass of 10Kg and a wingspan of 2m.

[russ_watters]

I don't think its anything to do with body density and muscle mass. If those were the problem, we wouldn't be able to fly WITH mechanical aid because we couldn't generate enough power.

The obvious problem is geometry. Human bodies don't have any parts that can work as a wing. 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.

[Danger]

Sorry, guys; I stated that badly. I meant certain muscles relative to other muscles, as well as to other species. Even with perfect artificial wings attached, I'm pretty sure that a human's chest muscles couldn't develop enough power to overcome the density of the body. I also don't think that a bird with solid bones could either. After all, bats have almost perfect flight adaptation for mammals, and they can't take off from ground level.

[FredGarvin]

In a way it is related to muscle density because of our skeletal systems. Ours are built like tanks compared to a bird's. That also decreases our range of motion and types of motions we can perform.

[Ivan Seeking]

One commercial enterprise seeks to build a hotel on the moon for rich folks. The planned entertainment includes a large enclosure where, due to the low gravity, people could be given wings to wear which would allow them to fly like birds. So if you want to fly, it may be as easy as a trip to the moon [or a space station]. :biggrin:

[FredGarvin]

I guess it's not worth pointing out that they would be more or less like a human super-ball instead of flying.

[Ivan Seeking]

I guess it's not worth pointing out that they would be more or less like a human super-ball instead of flying.

Do you mean when on a space station? I was thinking of the concepts for future designs that would produce low gravity using rotation. On the moon or under partial gravity in a space hotel, I would think that a true sense of flight would be possible.

[Ki Man]

here on earth, the closest thing we could get to powered by man flight without having pedals and gears and whatnot is a glider due to the size/structure of our deltoids and pecs. we'd have to be on steroids to get off the ground without assistance, and even then you'd have to be stronger than hercules (even if he existed)

[FredGarvin]

Do you mean when on a space station? I was thinking of the concepts for future designs that would produce low gravity using rotation. On the moon or under partial gravity in a space hotel, I would think that a true sense of flight would be possible.Yeah. That's what I was thinking.

[DaveC426913]

You know, if flying on the Moon in an enclosed area counts, then this should count too:

What if you created a dome here on Earth and kept the air pressure high? A high enough air pressure should allow enough lifting force to gain some human-powered flight.

[AlephZero]

What if you created a dome here on Earth and kept the air pressure high? A high enough air pressure should allow enough lifting force to gain some human-powered flight.

One small problem - after 10 minutes flight you might have to spend 10 hours in a decompression chamber recovering. Google "diving" for more info on the problems of breathing high pressure air.

[DaveC426913]

One small problem - after 10 minutes flight you might have to spend 10 hours in a decompression chamber recovering. Google "diving" for more info on the problems of breathing high pressure air.As an experienced diver, I don't need to Google to know that. But I'm not sure it's as black and white as you suggest.

[Ivan Seeking]

You know, if flying on the Moon in an enclosed area counts, then this should count too:

What if you created a dome here on Earth and kept the air pressure high? A high enough air pressure should allow enough lifting force to gain some human-powered flight.

The work for the flyer is the same less the slight increase in bouyancy.

[DaveC426913]

The work for the flyer is the same less the slight increase in bouyancy.

Why do you say that? The wings would be more efficient. More lift on downstroke and you can still minimize drag on upstroke.

[tehno]

Stupid question: can people fly? Evidently, one doesn't see people flying around the streets, but is it possible? Has anyone done studies on whether this is possible or not? Any articles on this would be highly appreciated. Has anyone actually done this?

Furthermore, how does physics apply to this? My rudimentary knowledge estimates roughly 800 N is needed for a 70 kg person to fly. Supposing one wanted to fly for 1 km, then this would be 800 000 J or 191 kC. And if one wanted to cover that 1 km in say 3 min, that'd be 64 kC/min, which is 3800 kC/hr, which is a hell of a lot. I believe that fast running takes about 1000 kC/hr. Then again, it'd still be a miracle if one could just fly 100 m. Please correct my physics if I'm wrong. In any case, how viable is this sort of calorie output for small amounts of time (e.g. 30 secs, a few minutes).

I would appreciate extremely any articles on studies done regarding this, and also if it's viable at all.

Thanks,

~sphoenixee~:rofl: :rofl:
I'm not an expert on this but I have heard that one guy also got interested in such things.I think he made even some progress in studying the problem
What was his name hmm..Leonardo ,Leonardo something...
Unfortunatelly,I lost his contact address but if he reads this maybe he will tell you what to do.

[AlephZero]

Back to basics - force = rate of change of momentum, so lift (and drag!) should be proportional to density if nothing else changes.

We know swans with mass 10Kg can fly in air with a 2m wingspan (though they need water to use as a "runway" to take off). It seems feasible a human could control 2m wings attached to the arms. So a 70Kg human may be able to generate enough lift at 7 times atmospheric pressure. That's equivalent to a water diving depth of 70m, and Google suggests breathing air at that pressure will have consequences - though I defer to those with first hand experience.

Actually, the civil engineering required to build a structure large enough to do "interesting" flying (and without any internal obstructions) and pressurizing it to 7x atmospheric would also be quite a challenge. The explosion if the building "burst" would be quite impressive.

[AlephZero]

:
What was his name hmm..Leonardo ,Leonardo something...
Unfortunatelly,I lost his contact address but if he reads this maybe he will tell you what to do.

Try http://www.danbrown.com/ :rolleyes:

[Ivan Seeking]

Why do you say that? The wings would be more efficient. More lift on downstroke and you can still minimize drag on upstroke.

This only means that you could use smaller wings. You still have to do the same amount of lifting work.

[russ_watters]

Why do you say that? The wings would be more efficient. More lift on downstroke and you can still minimize drag on upstroke. Lift is a force. More lift means more force that your arms have to provide. With denser air, you could produce more lift with smaller wings, but the lift required to keep you aloft is the same and therefore the torque on your shoulders is the same.

[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. :cool:

[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. :smile:

[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. :frown:)

[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. :frown:)

You do realize that diabetes never goes away :rolleyes:

[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 :rolleyes:
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. :biggrin:

[tehno]

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.

sphoenixeehttp://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. :biggrin:

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

[bowakowa]

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.