h a l f b a k e r yIncidentally, why isn't "spacecraft" another word for "interior design"?
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1. Photo 1 [see link] shows a person standing on a jet of compressed air.
2. The principle of kinesthetic control can be applied to air vehicles. Several experimental platforms show that kinesthetic control is a great way to control aircraft. [see link]
3. The so-called "air car" works on compressed
air; it uses lightweight air tanks containing air at very high pressure [see link]
4. Make a personal air skooter based on these three simple ideas.
:: no moving parts, only jets of air coming from high pressure air tanks
:: as with a skooter, you have only two directional controls: up and forward
:: left to right movement is entirely controlled by the body
:: the skooter is entirely made out of very lightweight materials, and lightweight airtanks
:: simple vents on the underside and backside release air which propells the thing upward and forward
5. As you sit on the airtanks, it is fairly easy to shift the weight and the centre of gravity, so that steering becomes easy.
6. Taking off vertically would use a lot of compressed air, but once you're airborne, you're sitting on top of a flying wing, and you only need forward propulsion.
Some person once jumped out of an airplane, and had small wings attached to his back, which made it possible for him to glide away a huge distance. He also landed without a parachute. [see link]
7. I don't know anything about physics.
8. See my photos about the megacool airskooter!!
Some person standing on a jet of air
http://www.howtoadv...lDavidHenderson.jpg
This person can fly out of ground effect [django, Feb 13 2006]
Kinesthetic control (Hiller platform)
http://www.nasm.si....raft/hiller_vz1.htm
The principle of kinesthetic control works [django, Feb 13 2006]
(?) Air car: 300 bars of compressed air onboard
http://www.theaircar.com/faq.html#p7
High pressure but lightweight - enough to propulse an airskooter with a person on it? [django, Feb 13 2006]
Airskooter showing tanks of compressed air
http://i3.photobuck...otertransparent.jpg
You sit on the airtanks [django, Feb 13 2006]
Airskooter underside showing jets
http://i3.photobuck...ransparentunder.jpg
It looks a bit like the space shuttle [django, Feb 13 2006]
Airskooter backside showing super air jet
http://i3.photobuck...parentunderback.jpg
These jets push the thing forward [django, Feb 13 2006]
All together now: airskooter safari
http://i3.photobuck...neumaskooterall.jpg
Someone should make airskooters and sell them [django, Feb 13 2006]
Some person with wings
http://www.gizmag.co.uk/go/3582/
He lands without a parachute. He is crazy. [django, Feb 13 2006]
Inspired by your post:
Air_20Boarding2
turn it on its head and it could be a cool new sport [gtoal, Feb 13 2006]
Some Japanese person with water bottle jetpack
http://video.google...8&q=britinaustin%20
Funny video of a person flying like a rocket [django, Feb 13 2006]
Scroll down to "Jump belt"
http://en.wikipedia.org/wiki/Jet_pack
[coprocephalous, Feb 14 2006]
(?) Buy a jet pack and learn to fly it.
http://www.rocketbelt.nl/site.html
[coprocephalous, Feb 14 2006]
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//lightweight air tanks containing air at very high pressure // Something of an oxymoron, I'm afraid. A 12 litre 300 bar steel scuba tank weighs around 14 kilogrammes - add maybe 75-100kg for a man, and you're looking at very short flight duration.
Carbon fibre composite tanks are mooted
Nice photo for reference 1 - looks like a particularly nasty form of execution.
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Hi coprocephalous! I don't know anything about air tanks. But the ones used by the Air Car are made out of carbon fibre over plastic, developed by EADS (Airbus). Wouldn't they be more lightweight than steel tanks? |
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How is this different from a normal hovercraft? |
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[django] My Spanish isn't too good, but I think the Minicat tanks are around 100litre capacity at 300 bar, and weigh 70 to 80 kg, so better than a scuba tank, but really not all that much - 0.8 kg/litre, versus 1.16 kg/litre for steel scuba tanks.
[EDIT] 100 litres of air at 300 bar (30 cubic metres at normal atmospheric pressure) itself weighs 37.5 kg. |
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[jutta] a hovercraft is termed a ground-effect vehicle, the air is trapped by a skirt. Here the exhaust is used directly, more like a rocket. |
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[jutta], what coprocephalous says.
Moreover, hovercrafts do not rely on kinesthetic control.
Once you're airborn, very small shifts in the centre of gravity make you able to steer the entire thing very easily. |
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so [coprocephalous] how long would you be able to lift yourself and the machine with such a 100 litre tank?
Say the person weighs 80 kilos, the tank + 100 litre air @300 bar weighs 100 kilo and the wing weighs 40 kilo (grand total: 220 kilo).
I don't know how to calculate this, with drag and resistance and all that.
Maybe it just doesn't work all that well.
Still, I'm buying one. |
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PS: I understand that rocket belts only take you up for half a minute or so. |
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If you and the machine weigh 220kg then the 37kg of air is going to have to be displaced rapidly downwards to give you any vertical momentum - so rapidly that it might displace your pelvis and smash your chin on the handlebars. Not to worry however, you will not travel too far away from terran based ambulance services. |
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//Moreover, hovercraft do not rely on kinesthetic control// Small racing ones do. |
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[consulflaminicus] I read the following somewhere: |
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"On February 2, 1951, in a large building on Wallops Island, Zimmerman mounted the jet board, a plain plywood rectangle, and slipped his feet under straps. Two flexible air hoses made a T connection with a short nozzle of 1 1/4-inch diameter that poked down through the center. Men stood ready at valves some distance away. An overhead crane hoisted him on suspension lines attached to his parachute body harness until he hung a few feet above the floor. |
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Zimmerman signaled for the air to be turned on. ***A piercing scream issued from the nozzle beneath him, but he felt nothing, no lift, no sensation. Then he glanced up at the suspension lines. They were dangling slack!*** |
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He had risen and was now actually balancing on a jet thrust -- **and he hadn't been aware of it!** For a full minute he stood there, in motionless wonder, then signaled and was let down. |
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It worked. It worked beyond the best anticipation of his theory. Balance control through the feet was so instinctive that it operated below the level of conscious thought. He went up and experienced it again. Paul Hill tried it. Testing further, they found that besides hovering perfectly by not thinking about it, you could control consciously, too--but here you tended to teeter your feet unnecessarily in a flurry of overcontrol. But you could travel without effort. Almost the wish alone caused imperceptible leaning and foot tilt, taking you to where you wanted to go, and stopping )'On when you reached there. Paul Hill became adept at sashaying around the 15-foot circle to which the dragging hoses limited him." |
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Yes, that is using an inexhaustable supply of compressed air delivered through hoses (you'll note the same thing in the picture in your primary link [django] ). Your machine relies on tanks of compressed air to provide the thrust, so a better comparison would be to look at the control, power and flight issues associated with a VTOL aircraft - google: "harrier VTOL design problems" for some hints as to the weight / thrust ratios required simply to get airborne using downwards facing jets. Your device won't have sufficient thrust for sufficiently long to get up to and maintain a speed where aerodynamic lift or ground effect will provide some lift. |
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But [consulflaminicus], your point was about people getting their pelvis broken and their chin smashed. I didn't agree, that's why I referred to the very gentle description of the dude experimenting with the air jet. Nothing indicates that it was somehow dangerous. On the contrary. "He stood there, in motionless wonder", standing gently on a jet of air. :-) |
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I do agree with you though on the problem of not having enough air on board to have a lot of fun. Someone with brains should calculate if it's feasible to make this work and have fun for 30 minutes or so. |
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[django] in this house, we obey the laws of thermodynamics. Two compressors working flat out to propel a weight of air downwards at sufficient speed to balance gravitational forces acting on a 80kg man plus plywood board can be controlled so that the forces balance - you have a limitless supply of compressed air to play with to get it right, gradually increasing the volume jetted downwards until equilibrium is reached. |
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On the other hand, if you are relying on just 37kg of onboard, available air to get a 220kg airscooter/rider combo airborne, then I think you need an explosive initial release, which equals high g acceleration. |
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Check out the hilarious video of some Japanese person strapping on a compressed air jet pack and launching himself. He does fly though! |
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//He does fly though// Hmm, I think not. Besides, water rockets use the water as reaction mass, not the air itself. |
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<<Hmm, I think not. Besides, water rockets use the water as reaction mass, not the air itself.>> |
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I'm sorry, I don't understand. The guy straps on empty waterbottles filled with compressed air, and gets propelled away. |
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What does water have anything to do with this? |
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//What does water have anything to do with this?//
Air is clearly seen bubbling through water at 3 seconds into the video and the launch assistant is soaked as the countdown reaches zero. The rest is faked. |
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[+] for putting it simply. Its quite obvious that it is doable, and you'll be seeing this soon. |
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Sadly, he's not landing without a parachute. See TED website or wikipedia for the current state of art. |
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You would like compressed air, because its "cleaner" and probably lighter than a jet motor, right? I would check both assumptions. |
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