Half a croissant, on a plate, with a sign in front of it saying '50c'
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Hot air balloon paraglider hybrid
  [vote for,

I am imagining a para-glider shaped balloon. Hot air balloon scale, of course. So two baskets, two burners with their associated vents and one lightweight arcing framework linking baskets (Can be inside the balloon, but more complex). Think two standard balloons leaning towards each in a kiss.

The balloon would have sewn structures, heat resistive strapping, to modify the balloon into a more an aerofoil shape. Control lines could be incorporated to have some collapse-able sections. This, with the advantage of venting, could allow for a shape changing hot air balloon wing.

So with a bit of Bernoulli's magic, the heat of burners and the pilots' skill, the balloon can have a new found freedom.

wjt, Nov 24 2017

Jetairship Jetairship
[theircompetitor, Nov 24 2017]

Inverting paper torus https://www.youtube...watch?v=G27dNeUjKWk
I made one from granite once just to see if I could. [2 fries shy of a happy meal, Nov 27 2017, last modified Dec 03 2017]

21Q, where are you? http://www.halfbakery.com/user/21_20Quest
[normzone, Dec 03 2017]

Phoenix airship https://newatlas.co...vehicle-fish/59434/
They're stealing our ideas again... [neutrinos_shadow, May 14 2019]

Wikipedia: Underwater glider https://en.wikipedi...i/Underwater_glider
The actual inspiration for the above? Works the same way, just underwater [notexactly, May 22 2019]


       ... to go wherever the wind blows it.   

       Without propulsion and control surfaces (apart from the envelope "wing-warping") it's still a free balloon, not a dirigible.
8th of 7, Nov 24 2017

       With a wing shape it's going to have a glide path.
wjt, Nov 24 2017

       To have a glide path, you need net weight. If you have a neutrally-bouyant balloon with no propulsion, it will just sit there in its own block of air, and go wherever the wind blows.
MaxwellBuchanan, Nov 24 2017

       ... four feet at a time.
pertinax, Nov 24 2017

       A venting balloon is going to fall with the direction of the wind. A wing shaped balloon falling is going to have another force vector. The two venting holes and section collapses will be able to twist the balloon in the wind.
wjt, Nov 24 2017

       Are you suggesting that you vent some of the gas to reshape the wing/balloon, go some direction you couldn't go with a regular balloon then refilling the envelope? If you're talking about emptying different sections of the balloon to somewhat direct its fall I suppose you could have your plummeting balloon move a bit to the left or right a couple of times before it emptied of gas then turned into a paraglider wing. Maybe I'm not clear what the goal it here.
doctorremulac3, Nov 24 2017

       The goal with most forms of aviation is to eventually resume contact with terra firma in a way that does not cause an unacceptable level of damage to the participant(s).
8th of 7, Nov 24 2017

       The goal is to use the aerofoil shape to give some directional control. The wing shape would alter flight characteristics of a ascending and descending hot air balloon. Collapsing/Sqeezing balloon sections as well as venting would change direction orientation.   

       An initial prototype would be enlarged paraglider with two pilots, poled out at either ends of the paragliding chute.
wjt, Nov 24 2017

       //Collapsing/Sqeezing balloon sections as well as venting would change direction orientation.//   

       You might be able to change orientation but not direction of movement. When you're lighter than air you're either hovering or moving up. The shape of the envelope might determine orientation but would have no effect on direction of movement which would just be with the prevailing wind. Think weather vane.   

       When you're heavier than air you can begin to act like a glider, changing the configuration of your wing to change direction but then you're a glider.   

       Put it this way. Take an airplane and attach a massive inflatable hydrogen balloon to it. When it's flying it has total control of wherever it's going but when you inflate that balloon, it doesn't matter how the control surfaces are oriented, assuming the engines of the plane are off, that vehicle is a balloon and that balloon is going wherever the wind is blowing.   

       As for the shape of the balloon, it could be Mickey Mouse from the Macy's Thanksgiving Day Parade or a series of fully manipulable flaps and ailerons, it's still substantially going the direction the wind is blowing.   

       So without adding any force for that control surface to fight against the wind with such as gravity (falling like in steerable parachute) or an engine (as in a paraglider) you're substantially at the mercy of the breeze. You might be able to get a little movement but not much.   

       Also keep in mind, any reshaping of that lighter than air envelope is just going to get that aforementioned wind vane effect. It will just turn into the orientation that puts the half of the ship with the most resistance down wind. An aileron leverages forward movement against oncoming air to change the attitude of the plane. With a balloon you have no such leverage. It would just turn until it hit the shape of least resistance and then continue to float in the direction the breeze is going.
doctorremulac3, Nov 24 2017

       Since it's a hybrid, and thermals are the bread and butter of a paraglider, I am thinking more paraglider flight dynamics than hot air dynamics. Which is what is wanted anyway.
wjt, Nov 25 2017

       Paragliders rely on aerodynamic lift, not buoyancy. They trade height for forward velocity, which generates lift. A moving (rising) mass like a thermal provides upward motion at a rate higher than the glideslope loss.
8th of 7, Nov 25 2017

       Sorry wjt, let the idea die with dignity. Time to pull the plug on this one.   

       First thing you want to do when inventing something is ask "What am I trying to achieve?" not "What happens if you combine a coffee pot with a football?"
doctorremulac3, Nov 25 2017

       //"What happens if you combine a coffee pot with a football?"// Rugby.
MaxwellBuchanan, Nov 25 2017

       // let the idea die with dignity //   

       Why ? Just bludgeon it with a rock, then throw it in a shallow unmarked grave.
8th of 7, Nov 25 2017

       So, here's a crucial point of the idea. How large can you scale up a paraglider?
wjt, Nov 25 2017

       I know where you're going, you're looking for a use for the football/coffee maker.   

       Ideas are like girlfriends, sometimes you just need to move on. This one's doing your friends, stealing your credit cards and probably has the clap.
doctorremulac3, Nov 25 2017

I worked out how to make this viable years ago. It's one of the few ideas I never posted because I would like to build the prototype some day.

       You just take all of the negatives everybody has mentioned, flip them all on their heads and those negatives all become positives.   

       The thing about yachting is that you can only do it two ways:   

       (a) Go completely with the wind, in which case you can have a very low drag in the water, and travel almost as fast as the wind.   

       (b) Go at an angle to the wind, in which case you need drag in the water so that the wind has something to work against.   

       With an unpowered aircraft, you basically have three options:   

       (a) Go completely with the air (ie, be a cloud)   

       (b) Trade altitude for speed relative to the air (ie, be a glider)   

       (c) Tether yourself to something and use that tether as leverage to travel at an angle to the wind (ie, be a kite).   

       [wjt] seems to want to go for option (d).   

       If it helps in thinking about any of this, just do all your thought experiments in still air and imagine the ground rushing past instead.
MaxwellBuchanan, Nov 26 2017

       //Nonsense. I worked out how to make this viable years ago.//   

       Well, time to build the prototype then. All I ask is that I get to watch the videos.   

       Just remember the first law of aerodynamics:   

       "Keep your design scientifically sound, or you'll end up a puddle of goo on the ground."   

       Orville Redenbacher, inventor of the modern airplane.   

       Happy yachting.
doctorremulac3, Nov 26 2017

       // venting //   

       A gas pump & pressure tank arrangement as used in most normal airships might be a better idea, then you don't lose your gas & can restore lift.   

       You can then reduce lift (to below neutral buoyancy) so you "can" glide & restore lift to regain altitude when your thermals run out.   

       What you have then is a hybrid glider / (helium?) balloon, was that what you were aiming for?
Skewed, Nov 26 2017

       // First thing you want to do when inventing something is ask "What am I trying to achieve?" not "What happens if you combine a coffee pot with a football?" //   

       Is that too long to be "marked for Tagline"? :))
Skewed, Nov 26 2017

       //Well, time to build the prototype then. All I ask is that I get to watch the videos.//   

       It’s all about the money... and my lack there of. Unfortunately you missed the opportunity to witness the first lift-to-weight ratio experiment where my neighbours got to wonder at the fifty foot black tentacle reaching over my house and waving down the street like the coming of Cthulhu or something.   

       Aw crap I won’t be the guy to build this thing anyway so I might as well put in the public domain like the rest of my brain-farts eh?   

       <stares thoughtfully into the distance>   

       Gather ‘round kids... little story time.   

       So like twenty years or so ago I was taking my private pilots license course, I got to where I could solo and then my instructor/buddy crashed his plane and died on a trip leaving a message on my machine asking me to join him as copilot to get ten free flying hours and knock about 1200 bucks off getting my license.
It gave me the willies and I never completed the course but it got me thinking about the safest aircraft which could ever be made.

       First of all, forget about lighter than air gasses and compressors. Solar energy is all that is required.   

       Picture a black or clear parafoil but about half the size of a football field which can be preheated to achieve vertical take off but relies on solar energy alone to stay aloft.
the shape of the wing is important as the body of the craft fluctuates between slightly negatively buoyant and slightly positively buoyant while being able to undulate like a manta ray.

       Once at altitude venting the heated air would cause descent allowing for hang-glider like weight displacement to control direction. If each of the tubes comprising the parafoil are segmented in such a way that cold air rushing in the front compresses the heated air through a series of baffled chambers, decreasing in volume, creating a slight passive solar jet then some substantial speeds might be attained while travelling with the wind.   

       I believe that enough excess solar radiation can be garnered while above cloud cover to power a UV light focussed up through an aperature on the underside of the canopy to keep the craft aloft at night. Elevation determines wind direction.   

       First 2fries, very sorry about your friend but glad you're ok.   

       What you're describing is sound but it's an airship. A parafoil shaped airship makes good sense and they've been around for a while. Here's the problem with asking too much of your venting to change the attitude, altitude and direction of your craft: you're going to need motors to get the thing moving anyway, so why not just point the ship down to land using old fashioned control surfaces?   

       The solar heated envelope would work as well but it's going to have to be very, very, very light so the cost of saving a few dollars on a propane tank and burners would be having to abandon any sort of useful carrying capacity.   

       The solar jet thing just doesn't have the enough going into the system to go out the other end to provide any sustained, useful thrust at all.   

       Finally, as far a gliders go, there's a reason you don't get on a glider at Heithrow bound for New York. You're falling, or perhaps skiing is a better analogy, along a slope of air looking for the next updraft. You go where you find them and when you don't find them, you land.   

       And also remember that you're making a deal with everything you add to your design. Want to get rid of that propeller? It'll cost you forward air speed. Want to loose that weight and get lighter than air? That will make your craft big and fat and that too will effect how fast your craft can go. Want to break the speed of sound? You're going to have to drop the lighter than air feature, etc etc.   

       This is what I mean by "Get your thinking back in the box." Sometimes the box is right. You only think outside the box when the box is wrong. In this case, the box says "Engine equipped lighter than air gas filled airship beats solar powered jet flying wing.".   

       Maybe rather than thinking outside the box we should just try to make the box bigger.   

       Ok, that last line sounds like the kind of crap you hear from eastern mystics that pisses me off, but you get the idea.
doctorremulac3, Nov 27 2017

       hmmm, the solar jetting only needs to provide enough thrust for the camber of the wing shape to generate lift. If used in stages then descent equals forward propulsion with no motor or propeller, and ascent would also have slight forward propulsion. Though you'd need to follow existing wind patterns to get any great distance this solar hot-air parafoil would be far safer than ballooning and I could see corporate sponsorship substantially lowering the cost of your rig if you were willing to say, fly your 1/2 a football-field sized Harley Davidson billboard over Daytona beach at certain times of the year... or a Coca Cola wing above Fort Lauderdale at spring break, etc.   

       I just want one.
With a secondary chute it's the safest aircraft I could dream up. Almost no moving parts. Unlimited power supply if I am right about storing enough energy to shine a UV light all night long.

       The question I have is; if you created four of these wings designed to pull against one another in four different directions, or perhaps a continuous ring-wing with inward venting, would individually controlling the solar jetting allow a platform to remain aloft indefinitely? Perhaps almost stationary even?   

       Well, there's just not any promise in the concept of "solar jetting". Just look at the volume of airflow through a jet engine then compare it to the volume of airflow through a passive solar balloon that takes cold air in one end, heats it up over a period of time using sunlight then spits it out the other end to provide forward movement. You might have enough force to bump the ship foward a few feet every few minutes but that's about it.   

       As far as playing around with a couple of black garbage bags taped into various shapes just to experiment with various solar balloon designs, no expense to do that. Might come up with some kind of advancement of the art with some tinkering.   

       And by the way, there's nothing wrong with making something work that's not as efficient as existing designs simply because it's something new. That can be very cool.   

       How about something where the payload moves around to make the envelope shape move in an advantagious manner? Maybe you've got a bird wing shaped affair where the gondola moves from one side to the other making the heavier "wing" drop to provide forward thrust then raise as the gondola moves along a cable to the other side. Just spitballing here. I don't want to come off as the "Solar Balloon Grinch" spoiling all the fun.
doctorremulac3, Nov 27 2017

       Spitballing is cool.
I question your evaluation of the passive solar jet given that the body of the craft fluctuates between slightly negatively buoyant and slightly positively buoyant while being able to undulate like a manta ray.

       While we're spitballing there's another way as well.
It's pretty funky though and totally relies on no wind.

       If you were to make tetrahedrons and connect them together on hinges if creates a Flexahedron, which is basically an origami torus ring. This shape would allow a solar hot air craft to propel itself by inverting.

       // origami torus ring // // propel itself by inverting //   

       Cool idea, would look great in action :)   

       Or just do it like a jellyfish with a large flexible / elastic sheet or diaphragm, stretch it out toward the desired direction of travel & release (not sure (thinking about it, as you suck air in the back as you stretch it forward) if that would work at all though, how do jellyfish do it?).
Skewed, Nov 28 2017

       // the craft fluctuates between slightly negatively buoyant and slightly positively buoyant while being able to undulate like a manta ray.//   

       I get the idea, it's clever but you're short of horsepower to get any movement.   

       You should go back and put that description at the very beginning. It's the clearest picture of what you're talking about.
doctorremulac3, Nov 28 2017


       There are autonomous submersibles that alternate between bouyancy and sinkancy, working like underwater gliders on both ascent and descent.
MaxwellBuchanan, Nov 28 2017

       I was thinking some kind of corkscrew movement might be something to consider. This is going to be really hard to describe.   

       1- Long spring shaped envelope devided into multiple compartments.   

       2- Visualize the top half and the bottom half. At any one time half the compartments are at the top, half are at the bottom.   

       3- Now visualize the bottom half being black on the top portion to absorb heat.   

       4- Visualize the top have of the current* top portion being reflective to reflect light and reject heat. *(current because the thing turns, top becoming bottom, bottom becoming top)   

       So the idea is, the bottom half gets hot, rises and rotates the spring giving forward motion like a propeller. Once it gets to the top, it rotates into a configuration that rejects heat and it cools off while the now bottom section starts to gain heat.   

       It's a really simple idea but I don't know if I've illustrated it to any useful extent. Anyway, on a completely windless day this might move a little bit.   

       You might need 3 sets of compartments to get the rotation, not sure.
doctorremulac3, Nov 28 2017

       That is a cool idea, [doc].
MaxwellBuchanan, Nov 28 2017

       Thanks Max. At least whether or not it would work is up in the air.   

       Could also put this on the ground and use it to make the world's weakest solar powered motor.
doctorremulac3, Nov 28 2017

       You could also try it underwater.
MaxwellBuchanan, Nov 28 2017

       Now ...   

       Conversion efficiency. PV cells are only a few percent efficient at best, yet super high altitude solar-powered drones are under consideration and may be a viable technology.   

       Now, could a solar-heated ram turbine do better ?   

       Hollow, thick-chord, low speed wing - transparent upper surface, lower interior surface coated in vantablack, and insulation below. Turbine inducts air into wing interior, which is heated by solar input. Heated air exhausts via a second turbine, shaft-coupled to the intake. Temperatures won't be high, so the blades can be fabricated from composites.   

       There will be a small amount of thrust from the exhaust air, but the main propulsion would come from a direct-driven low-speed prop geared down from the turbine shaft.
8th of 7, Nov 28 2017

       //You could also try it underwater//   

       Problem is, the light wouldn't get to that bottom section you want to heat up and make raise to turn the thing. Some kind of inverted version might make an interesting boat though. You've got cold water to provide a greater temperature difference. No idea how you'd do it though.   

       8, sounds like you're doing real and practical engineering there. I'm just spending some time in the "Dr Seus School of Wildly Impractical Contraption Design". But the enemy of that idea is the mass of the envelopes needed to cook all this air. Would you get enought temperature differential to get a prop turning fast enough to move the thing? Maybe. I'm thinking long sausage shaped thing for minimum drag with the prop at the front might work.   

       I was also thinking of a undulating serpent in the water thing with the alternating heating / cooling compartments idea before the corkscrew thing but a propeller would probably be the way to go.   

       Frankly this sounds like it would make for an interesting competition. Fastest non-photocell sun powered aircraft design competition.   

       The breakthrough would be somebody actually getting something to fly because of that catch 22. The more air movement you get, the more horsepower you get but with more air movement comes more air, bigger envelopes and more drag and weight.   

       I'm going to go ahead and bun this idea because I like the conundrum. Now I want to make a flying sun powered balloon-plane thingy just because that nagging Jiminy Cricket of practical engineering rules in the back of my mind is telling me it can't be done.
doctorremulac3, Nov 28 2017

       How about one big ass propeller that works like this:   

       It's got a series of sun blocking skirts that fall open and allow sun to enter and heat air on the bottom blades but when the blades float up (turning and pushing the thing forward) the skirts or shades fall down and block the sun allowing the thing to cool, lighten and continue turning but this time down where the sun blockers open up again.   

       So in the down position, sun blocking venetian blinds fall open, in the up position they fall shut. Kind of a variation of the corkscrew thing but could be several hundred feet tall so at the outer edge of those blades even some slow turning propeller could result in some pretty fast speeds towards the tips resulting in a reasonable forward thrust. To give the thing some structural stability you'd just have them pumped very full of air.   

       Actually, just occurred to me you don't need the skirts. Since it's a propeller blade that's twisted, you have one side absorb light, the other reflect it. Just have the sun hit it from the side.
doctorremulac3, Nov 28 2017

       // How about one big ass propeller that works like this // // It's got a series of sun blocking skirts that fall open and allow sun to enter //   

       Why not just use a solar mill (not that I think that would work mind) ?
Skewed, Nov 28 2017

       Solar mills (Crookes radiometer) operate only in near-vacuum conditions and with ultra-low friction bearings. They don't work at atmospheric pressure.
8th of 7, Nov 28 2017

       Well, there is that :)
Skewed, Nov 28 2017

       //Why not just use a solar mill, not that I think that would work.//   

doctorremulac3, Nov 28 2017

       Non-photocell... Can I use a focal mirror and a stirling engine turbine?   

       We had one of those “Air Swimmer” toys that propelled itself with a fish tail action. I see the big Manta Ray as one of those turned sideways.
RayfordSteele, Nov 28 2017

       No, that would be a cetacean.   

       A ray does obtain propulsion from vertical movements, but of its "wings".   

       Dolphins and sharks are both marine predators, one employing up/down tail motion (causing constant pitch variation), the other using side-to-side motion causing variation in yaw. Clearly both approaches are valid for the species concerned, since they continue to exist.   

       They do not, however, require "lift", having approximate neutral buoyancy.   

       Birds derive both lift and propulsion from their wings, usefully gaining both from one set of muscles. If birds used tail motion for propulsion they would need extra muscles, hence more mass. This would be less "cost-effective", and no doubt the forces of evolution would have some input on such a design.   

       If birds were neutrally buoyant in air, then oscillating-tail drive might be practical.This would mean that such a creature - essentally a large, slow-moving bag of gas with a very small brain* - would need a means of generating and containing elemental hydrogen, not a biological impossibility.   

       This would be a fire risk, but helium would be impractical as an alternative lift gas since, lacking grasping appendages, birds** would be unable to operate the valves on the cylinders.   

       *very like Donald Tusk, but smarter and with more charisma, I.e. some charisma.   

       **Some larger raptors might well have enough strength and dexterity to work gas taps, but if using buoyant rather than aerodynamic lift would most likely be unable to execute their normal hunting techniques, resulting in starvation ; a classic example of maladaption to technological change.
8th of 7, Nov 28 2017

       Sp. "**"
Gr. ")"
//nirmal hunting// This is now prohibited, except among those indigenous people-groups whose totem animals find it amusing. Ochre must be worn.
pertinax, Nov 29 2017

       That's the problem with thought design , a vast gap between actual happening and the second and third design iterations.   

       May I suggest an oversized paraglider with the cells pumped with hot air, some small gas burners until scale gets exceptional, to see what the data says. Oh and the handling.
wjt, Dec 02 2017

       Well, I can give you that data right now. With the addition of gas burners, you'd get a floating flying wing shaped balloon. For it to be controllable you'd need to add some way to control it. To design this control system you'd have to ask "Where do you want it to go?". If you want it to fly against the wind, you need to loose the buoyancy and have it fall or put some kind of thrust mechanism on it. There's no 3rd option.   

       Gonna do one last quick review. First let's look at what it's doing now. It's going wherever the wind blows it. Put it next to the Macy's Thanksgiving Day Parade Micky Mouse float and let them both go, they're traveling in the exact same direction. Each will turn into the wind such that it will pivot on the center of pressure such that the side that offers more resistance to the wind will turn downwind and the side that offers less resistance will turn upwind. To simplify, a rocket shaped balloon will float away with the pointy part facing into the wind that's blowing it.   

       Now with the deflating, inflating thing you're talking about, you might change the shape and the orientation, but to get useful movement out of it you're going to have to start thinking about how much energy you have to work with. When you deflate a section between the two wings to have it flap for instance, does it happen fast enough to get any useful forward motion? Watch how fast a hot air balloon takes to fill up. It's very slow. Not a lot of promise in using the inflating and deflating of one of those things to harness the difference between a full and empty chamber to get some kind of forward motion going.   

       My years of designing rockets when I was about 8 to 10 years old required me to spend many minutes learning about thrust to weight ratios, center of pressure, center of mass, angle of attack, control surface design etc. I believe my entire academic career spent on this subject took the better part of a half hour, certainly at least 20 minutes so I know about this stuff. Rocket scientist might not be the right title, but I am qualified with this extensive experience to save my fellow man from bad aircraft design. I don't like to use the term "hero" loosely but... well, in this case.   

       So, understanding that we're just having fun here, this is this morning's idea to get one of these things moving.   

       Flapping Flying Wing Balloon.   

       Have the wings set up such that there is a very tight set of springs holding it in place in the up position or the down position. To move from one to the other would require a great deal of force but not a lot of distance to be covered.   

       You have two sets of inflatable envelopes or envelope sections, at the tips of the wings, and at the middle of the craft.   

       To start the cycle, you have the wings in the down position. You route your hot gas from the burners to the wing tip envelopes and open the center envelopes. This causes the tips to raise and the center to fall. This wouldn't happen very fast on its own but remember, you have those springs. As soon as it reaches the point where the springs are at maximum stretching, they cross over from pullling the wings together into the down position to pulling the wings together in the up position so they "snap", thus giving you some useful forward motion. You then reverse the process, empty the wing tip bags while filling the center bags until you "snap" into the downward position.   

       If there was absolutely no wind, like in a large aircraft hangar or something, this thing might be able to fly from one side to the other in a few minutes using the "deforming of shape" thing that I think you wanted to achieve.
doctorremulac3, Dec 02 2017

       //a rocket shaped balloon will float away with the pointy part facing into the wind that's blowing it. //   

       I don't think it will. A rocket shaped balloon moving with the wind will behave in the same way as a rocket shaped balloon in still air - the only difference is that the ground is moving past in one case and not in the other. The balloon will have no definite orientation.   

       However, if the wind is gusting, that would be different because the balloon's inertia will act as a drag when the wind speed picks up.
MaxwellBuchanan, Dec 02 2017

       Springs are heavy though.   

       I was thinking that the pilot would be the spring.
While gliding the weight of the pilot is distributed fairly equally across the entire span of the wing. By forcing all of the weight to momentarily be suspended slightly forward of middle and slightly to either side of the longitudinal mid-section of the wing, say by standing up from a seated position, thereby transferring all weight to the feet of the pilot to just those two points, and then sitting again, a wave will be created along the entire leading edge of the craft radiating outwards towards the wing-tips, This will have a whip effect, and placing more weight on one foot or the other will bank and turn the craft as well.
Once the pilot has found a rhythm to the oscillations the thing will move a lot of air rearwards, but still won't let you fly into anything other than a slight breeze.

       The only way to travel distances is to find an altitude where the wind is blowing your way, otherwise I see the combination of buoyancy fluctuation, solar jet, and mechanical undulations allowing one to "tack" into the wind while finding the right altitude.   

       The coolest thing about actually pulling this off will be flying it with impunity until laws have been written restricting you from doing so.
It's not a motorized aircraft.
It's not a glider.
It's not a fixed wing aircraft.
It's not a hot air balloon.
It's not a parachute.

       It's a big'ol' snub your nose at the FAA.
The ensuing court case would generate more media hype than you could ever afford for advertising.

       //I don't think it will. A rocket shaped balloon moving with the wind will behave in the same way as a rocket shaped balloon in still air - the only difference is that the ground is moving past in one case and not in the other. The balloon will have no definite orientation.//   

       Might want to rethink that Max, look at a weather vane or an arrow or rocket shaped balloon.   

       We're looking at it from the direction the wind is coming from. The arrow, rocket or weather vane shaped ballon is at a right angle to us currently. On the right side from our point of view are the fins. On the left side is the tip of the arrow, vane or rocket.   

       Now the wind hits this object. The area of the left hand side of the object is X, the area on the right, the fins or feathers part is several times X in terms of area. Both areas are subject to the same speed of wind. The section with greatest area is going to have more force pressing against it, since it's catching more wind and that will rotate the balloon so the lesser area section turns up wind.   

       Put another way, take a toy rocket or arrow and throw it. It will orient itself according to its center of pressure/center of mass ratio. There's no difference between you moving the fluid (air) against this object via wind or throwing the object into the fluid, it will orient itself based on which bits offer the most resistance.
doctorremulac3, Dec 02 2017

       //Springs are heavy though.//   

       I meant to say rubber bands.   

       Very light in relationship to the vehicle and able to store lots of potential energy.
doctorremulac3, Dec 02 2017

       //look at a weather vane or an arrow or rocket shaped balloon. // Those are tethered. I assumed you were talking about an untethered, rocket-shaped balloon. If so, it will move with the same speed as the wind, and hence experiences the same forces as it would in still air.   

       However, if you meant a *tethered* rocket-shaped balloon, then all is well.
MaxwellBuchanan, Dec 02 2017

       Well, ask yourself, what happens to an un- teathered toy rocket or un-teathered arrow you throw into the wind? In fact, go ahead and throw it tail first. Maybe I'm not clear, but we're not talking about anything but the orientation of the craft. All un- teathered shapes will move with the wind, I'm just talking about which direction they'd be pointing.   

       There actually is a kind of "tethering" taking place because the object has mass, even though it's lighter than air, it doesn't want to move.   

       When you hit it with wind, the part of that object (with mass) that has the greater surface area will collect more pressure from the wind. The area (with mass) that has less area will collect less pressure and it will turn accordingly. If you have an oblong object and a weak man pushes in on the left side and a strong man pushes it on the right side, it will turn towards the weak man.   

       As far as your design 21, I'm not sure but I think you're just using pilot weight to re-orient the craft like with a hang glider. Well, ok I guess. Still unclear on what's trying to be achieved here.   

       As to whether or not my snap wing design would work... ahdhunno. How could it be improved? Throw the entire design in the garbage and get yourself a piston engine powered dirigible.   

       Bottom line, I'm excited about entering into this design competition, I just don't know what would have to be achieved to win. "Balloony wingy thingy that kind of moves around without power but is jetty and reconfigury" is a little vague and confusing.
doctorremulac3, Dec 02 2017

       [doc], [doc], [doc].   

       When you throw something, it has speed *relative to* the air. That's important.   

       Likewise, if you release an object in a wind, it _initially_ has speed *relative to* the air, because its inertia means that it takes some time to accelerate up to the same speed as the air.   

       But, if you release a bouyant object (like a rocket-shaped balloon) into the wind, within a second or two it will be travelling at the same speed as the wind. At this point, there are no aerodynamic forces acting on it, and its shape will have no impact on its orientation about a horizontal axis.   

       Really, truly, this is how the world works.   

       For bonus points, tell me what happens to a balloon floating in still air if you decide to move the ground past underneath it.
MaxwellBuchanan, Dec 02 2017

       With nature not being perfect, no wind is a uniform pressure. An object, I imagine, will orientate itself due it's shape and the changing on coming pressure variations in the wind.   

       // move the ground past underneath it// The air closest to the ground will get nooked and be dragged along. This will cause layers of faster moving air, which is less dense, so the balloon will be sucked down? maybe.
wjt, Dec 02 2017

       Yes, as I mentioned earlier, a gusting wind will leave the balloon momentarily slower than the surrounding air, at which point it will experience drag orienting it. However, when the gust finishes, the reverse applies and the orientation will change.   

       My point was that, in a steady wind, no shape of untethered, unpropelled balloon will orient itself in the horizontal plane.
MaxwellBuchanan, Dec 02 2017

       Max, Max, Max.   

       //a rocket shaped balloon will float away with the pointy part facing into the wind that's blowing it. //   

       True or false?
doctorremulac3, Dec 02 2017

       False. It will start out (when you release it), pointy end into the wind. After 1-2 seconds, it will be travelling at the same speed, and its orientation will drift randomly.   

       Maybe I can simplify things a little. Suppose the wind is blowing at 10mph. You've released the balloon a few seconds ago, so it is also travelling at 10mph. The speed of the air relative to the balloon is 10-10 = 0 mph. Now, what forces are aligning the balloon in the horizontal plane?
MaxwellBuchanan, Dec 02 2017

       //False. It will start out (when you release it), pointy end into the wind.//   

       I think you meant to say "True. It will start out (when you release it), pointy end into the wind."
doctorremulac3, Dec 02 2017

       Answer as above, if your balloon isn't tethered or propelled, and once it has had a couple of seconds since release to be moving at the same speed as the wind.   

       Also question as above.
MaxwellBuchanan, Dec 02 2017

       OK, we may be talking at crossed wires here.   

       If you hold the balloon by its pointy end, then yes, as long as you hold it, it will trail like a streamer.   

       I thought you were saying that it would *keep* pointing into the wind once you release it, which it won't - it's orientation will wander about, effectively at random, because there are no horizontal forces acting on it.
MaxwellBuchanan, Dec 02 2017

       I understand what you're saying and you're correct, but the point I was trying to make was that changing envelope shape (I seem to remember that was the original idea way back there someplace) was useless as a method of getting this thing moving. You release the tether, it floats up and you change your shape and then rotate a certain way but that's about it.   

       We're still trying to get this thing to move right?   

       I'm so vague on this design I don't even know what I'm trying to critique.
doctorremulac3, Dec 02 2017

       Oh, well, I lost track of the whole make-it-move thing.   

       Basically, if you want to make it move, you have a few options (other than putting a propellor on it).   

       (1) Make it flap some wings
(2) Make it alternately float and sink, and ride the glideslope in both cases
(3) Make it throw some air backwards, for instance by having a wide bulge that travels backwards along the length of the balloon; or any other shape-change that throws air backwards.
(4) Variations on 1-3.
MaxwellBuchanan, Dec 02 2017

       But what about my snap wing design? Yes? No? I think it could make some moving movements.   

       I think in an aircraft hanger with no wind you could get to... 1, 2 miles per hour average in little bursts.
doctorremulac3, Dec 02 2017

       Ah, OK. So, you're basically flapping, with rubber bands to accelerate part of the flap. Yes, sure, if everything's the right shape.
MaxwellBuchanan, Dec 02 2017

       Wjt? Is this a solution that fits your design requirements? It’s a reshapey movingish “flying” thing.
doctorremulac3, Dec 02 2017

       // when I was about 8 to 10 years old ... spend many minutes learning about thrust to weight ratios, center of pressure, center of mass, angle of attack, control surface design etc. ... better part of a half hour, certainly at least 20 minutes so I know about this stuff. //   

       WOW. Respect ....
8th of 7, Dec 02 2017

       // Basically, if you want to make it move, you have a few options (other than putting a propellor on it).   

       (1) Make it flap some wings
(2) Make it alternately float and sink, and ride the glideslope in both cases
(3) Make it throw some air backwards, for instance by having a wide bulge that travels backwards along the length of the balloon; or any other shape-change that throws air backwards.
(4) Variations on 1-3.//

       (1) Check. Like a Manta ray.
(2) Check. Close flaps ascend, open flaps descend.
(3) Check. Passive solar jetting of expanding air able to be augmented with focussed heat lamp.
(4) Check. All of the above in one almost-no-moving-parts package.

       I can build a working scale prototype by feel if the maths can be derived from a working model, and I volunteer to test pilot the man-powered contraption once it's past the initial stress-testing phase.
If any group could work all of the kinks out it's this one, we just need a financier or crowd source funding to be able to put that [Halbakery Against The Real World] category into practice.

       Who's with me?!...
with me?!..
th me?


       <sound of crickets>
<tumbleweed rolls by in the distance>

       //I volunteer to test pilot the man-powered contraption// That's a remarkable coincidence. I was about to volunteer you too.
MaxwellBuchanan, Dec 02 2017

       I know, right?! It's perfect...   

       Wanna bet me I can't get a scale model prototype to fly?   

       Maybe if I put another 20 minutes into my aerospace engineering studies* I can come up with some better solutions.   

       *And I've seen the movie Apollo 13 twice.
doctorremulac3, Dec 02 2017

       //As far as your design 21, I'm not sure but I think you're just using pilot weight to re-orient the craft like with a hang glider. Well, ok I guess. Still unclear on what's trying to be achieved here. //   

       21 has not added an annotation to this idea yet.   

       Yes, but you need to remember that [21Quest] had his account hacked and many annos were lost. At that point the rest of us graciously assumed the responsibility for replacing those lost annos and links.   

       So, on his behalf:   

       This idea would work much better if we spent our time looking for ways to improve inter-aircraft communication while looking at and voting up or commenting my ideas at (see link)
normzone, Dec 03 2017

       //Wanna bet me I can't get a scale model prototype to fly?//   

       No, because it's theoretically possible and technically reasonable. I'd put your chances at 1 in 10, depending on how much time and effort you put in.
MaxwellBuchanan, Dec 03 2017

       I meant to type 2. Hit the 1 as well by accident.   

       Still have no idea what the goal is here.
doctorremulac3, Dec 03 2017

       /Wanna bet me I can't get a scale model prototype to fly?/   

       //No, because it's theoretically possible and technically reasonable.//   

       Too bad. This is one I really want to see made real. Truth be told though I'm a bit relieved. I could make it work, but my time has already been stretched more than I thought possible.   

       // my time has already been stretched more than I thought possible. //   

       That's just your own carelessness, for traveling at high relativistic velocities in normal space - it's all clearly defined by Einstein's theory.   

       Learn to slow down, take it easy. Don't go above 0.1 C. If you need to cover long distances quickly, use a non-Newtonian propulsion system with temporal distortion compensation.
8th of 7, Dec 03 2017

       I've tried those - rented ship, courtesy of Borg-U-Go. They're crap. You get there shortly before you've left, and then they double-charge you the rental because you're using two ships at the same time, only they don't yet have the record of your paying the first rental charge, you end up paying three times over. It's a scam - go with Rom-U-Like or Cardasshire.
MaxwellBuchanan, Dec 04 2017

       I concede that the strongest current of energy change has the last say but await future discoveries of physical manipulation that could be used to harness energy into realistic, complex, counter intuitive flights of fancy.
wjt, May 13 2019


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