The logic sounds reasonable, though there are some daunting design challenges. Of the two links, the first one is a lot sexier looking, but it's also a lot more speculative. I doubt it will ever fly. The second one looks more realistic, but it isn't very sleek or sexy.

The reason they have more than two wheels is pretty obvious. They have fully enclosed cockpits, making it impossible to put your feet down. Maybe you were thinking of something that you straddle in the conventional motorcycle fashion, like a Star Wars Speed Bike. This would enable you to put your feet down and would probably be a lot lighter in general. The disadvantage would be the poor aerodynamics. This would be a big problem at high speeds. One of the disadvantages of small wings is that you have to fly faster to generate enough lift, so having small wings and an open, high-drag design would work against each other. Maybe you were planning to have a mostly enclosed cockpit with openings for your legs.

You described the wings, but I really couldn't figure out the layout you had in mind. It's a shame you can't post drawings here as that would help a lot. It sounds like there is an 8 ft wide wing that unfolds to provide 18 ft wing span. If the 8 ft span can't be reduced, you are going to have a problem using it on the road. Normal cars are about 6 ft wide, humvees are about 7ft wide. I believe 8 ft wide vehicles require "wide load" signs and special permits.

You suggested making the vehicle shorter, this may not be a good idea. The distance between the wing and elevator (canard) has to be sufficient or the craft will have stability problems. The Wright bros "Flyer" was barely flyable until they increased it length.

Though automated cars are not usable yet, computer controlled aircraft are already common. Many airliners are actually capable of taking off, flying to their destination and landing without pilot assistance.

Something along the lines of an ultra-light aircraft might work. For a while there were experiments with inflatable wings which might be practical for the road when collapsed like a parachute. The engine could be connected to an air compressor to inflate the wings for flying.

Dwane, my design will sit feet-forward like a scooter or like the Litestar motorcycle. I'll leave it will be totally enclosed, but I'll leave closable doors in the bottom that can suffice for putting your feet down.

As for the length vs. wingspan and wing area, I've designed models for years, so I think I can get those figured out. I have software, too. I can short on the wing span because I get the additional wing area from the lower wing. I'm drawing an 8-foot wing with a four-foot chord. In Kansas, the max legal vehicle width is 8' 6" with no 'wide load' sign. Though I know driving a vehicle that wide is a pain (my horse trailer), I don't figure I'll spend most of my time on the ground.

I'm able to come up with about 96 sq ft of wing (easily enough for two people), though I know that a low-aspect wing is 'draggy'. Still, like I said, there are lots of 1-seat planes with less span and half that area. Really, I think it could fly with only the eight-foot of span and no folding if the gyro effect of the back wheel is as good as I think it will be. I'll use end-plates too.

To understand my upper wing design, just think of a drop-leaf table eight foot wide, with two five-foot drop sides. The biplane's lower wing is below. The outboard sections are slightly swept, to match the set-back of the lower wing. I'm hoping to get a website eventually...

Sand is right, there is good research on inflatable wings and there are also flying motorcycle designs actually flying today that are gyrocopters and powered parachutes. Unfortunately, these are all very speed limited. I'm hoping for something like 120 mph (not those ridiculous 385 mph speeds that Moller quotes), but more than 60mph that a ‘chute or inflatable would be able to do. Ducted fans are very speed-dependent--you need to plan to design them for one speed. The Samsonmotorworks ducted fan looks like a bad design--there's no true 'duct'.

Here's the gyro and parachute flying motorcycles:

http://www.thebutterflyllc.com/sscycle/gallery.htm

http://www.ultralightflying.com/archives/flite.html

As for connecting the engine to an air compressor, I think that's fine but more weight, I could get 10psi of pressure from ram-air: that would inflate a wing. Or in my design, inflate a couple two-liter bottles that'll store the pressure to unfold the wings. Or use exhaust pressure?

Dwane, when I saw that Star Wars movie, I figured the flying motorcycles would come out of the closets. Not really until now...

As someone who has flown light aircraft, after the initial delight in merely getting up in the air and fooling around, I finally found it was such a nuisance to have to use an airport to use an airplane and finally discovering that frequently weather conditions made travel more difficult and slower than an automobile, neglecting the expense of the operations, that I lost my taste for flying. If a small aircraft could land, perhaps, on a roof downtown and take off from a highway almost anywhere it might finally be useful gadget.

I don't see how the gyro effect of the rear wheel would affect the wing size. It isn't going to reduce the need for lift. Stability in the roll axis isn't usually a problem anyway, especially with a high-mounted wing design. Speaking of which, why did you choose to have the wings fold down instead of up? This forces you to mount the wing very high, about 7 to 8 feet to allow the bike to lean safely on the road. If they folded up, you could have longer tips and a shorter middle span while increasing overall wing span. The wings could be attached directly to the motorcycle frame instead of being mounted high above it somehow. This would also lower the center of gravity on the road, which would make it safer and easier to ride. When folded, the wings tips could be secured together forming a triangle, which would make it even more compact and stable. Most airplanes with folding wings (such as carrier based fighters) have wings that fold up, so it is a proven design. Roll stability could be maintained by using a dihedral design.

If you want to decrease the folded size of the wings even more, you could have each wing fold in two places instead of just one. When fully folded, the wings would form an M shape instead of an triangle.

Dwane, the area of the lifting wing(s) is easily increased by increasing chord, so not having enough area isn't a problem. Also, I could use a higher lift (higher drag) airfoil. But this puts me in the catagory of a 'low aspect ratio' wide-not-long, wing, which can work fine and allow for a large speed envelope, but generally have more drag than longer wingspans.

The reason I'm concerned about roll stability is because a long span gives the wingtips a longer lever-arm to easily right you--a shorter span is easily perturbed in roll and takes more vigilance to keep upright. It's similar to the length issue you mentioned eariler for a short-coupled plane (with a small 'tail volume' like the Wright plane), it becomes unstable in pitch.

I'd rather fold down than up because I can put a permanent stop on an up-fold. Most wings are seldom loaded negatively (like flying upside down) but always loaded--to multiple g's--positively. I don't have to trust my life to a locking pin, only an over-center elbow toggle-type strut. The wing should never fail and leave me with no span. I see this as 'fail-safe'. But also, like I said, I've considered building this in a model that doesn't have any folding tips at all.

Right now, I've only built a test model with a full-moving canard (not something I've ever seen) and two inline motorcycle wheels, the front turnable to see if it would work okay as a rudder.

I'm okay with a top-wing that's five-foot above ground at center, six-feet at the full-widths and only allows for one foot of lean. But I haven't built this, so it's all conjecture for now. The plane 'hangs' from a top-wing, so it will add to stability to be taller. I plan lots of dihedral, too. Good for short wingspans, like you said.

I wouldn't do double-folding because of the complexity. Terrifugia is planning this on it's 'flying car' but I think it will keep them from ever succeeding. Again, it's not fail-safe.

http://www.terrafugia.com/

But truely, the way I would do it vs. the 'right' way may not be one and the same and if you want to start designing a flying motorcycle, I'll be pleased to see yours, too.

Thanks for the Terrafugia link, really cool design. I don't think the double folding wing is a problem at all. If they fail, it will be due to financial or legal problems. You might not feel that fold up wings are fail safe, but they've been used on dozens if not hundreds of successful designs, including high performance fighter planes that stress their wings far more than you ever will. Thousands of carrier based planes fought in WWII, often in intense dogfights and dive bombing runs. I've never heard of the wings failing unless they were shot off.

I'm not going to attempt to design a flying motorcycle, I'm certainly not qualified. I hope you will forgive my arrogance in trying to tell you how to do it, but you posted the idea on Why Not, so I would assume that you would expect constructive criticism, especially from me.

Yes, planes with folding wings work. But it's a weight, cost and complexity penalty. I'm hoping to avoid those problem.

As for qualified, I'm not either, but I've discovered that people that design things (myself too) aren't usually qualified until they've already designed one. Horse and cart problem.

Your comments are appreciated. I wish more people would say at least a sentence. I see all of the hits on these ideas, but few comments. Bummer.

Perhaps one general comment is worthwhile. The motorcycle, even with all the flashy additions, is a minimum transportation vehicle and a good deal of its value is the ease of its moving through traffic where larger vehicles get jammed up. Its current ruggedness depends upon its heavy structural elements which are no drawback for a ground vehicle. But when the thing must fly the weight becomes a real problem and redesigned elements have to sacrifice some of the ruggedness. Some of this can be offset by using more expensive lighter materials. The only aircraft that seems to match these qualities is the ultralight but anything that flies and can carry the weight of a rider plus elements required for ground travel requires rather large surface areas for generating the required lift. These large area components are a real nuisance for minimum ground travel and folding can compact them to a degree but they really screw up the sense of a minimum ground travel vehicle. My suggestion of inflatable or para-wing airfoils would permit maximum compaction for ground travel but even then compromise the ease and flexibility of a motorcycle.Those models I have seen displayed seem to concentrate on a kind of flashy Buck Rogers look with streamlined panels that might add some use for minimizing air drag but add considerable weight which is poison in a minimum vehicle. Perhaps lightweight inflatable plastic panels might be able to streamline the vehicle when airborne without adding too much weight. Either way, the ideal of an ultralight aircraft and a minimum land travel vehicle have conflicting problems which frustrate optimum operation in either medium.

sand, I agree with your comments about motorcycles being useful because of their minimum-ness. This design would institute a fully new kind of vehicle that wouldn't have the same advantages of either the motorbike or the plane.

Your continued mention of ultralights is mostly on-target for the kind of design I'm talking about, though it's not the same as the links I've added. I believe in small motorcycles-and I've ridden dirt-bikes, too. Weight is paramount in small bikes. They already use aluminum extensively, etc. Like in planes. But I wouldn't be aiming for the under 250lb and no-license to fly 'legal' ultralight market. These reside in the margins of aviation.

But there IS a huge market for the motorcyle as a 'cruising' vehicle--here in center US, people ride these great-big Harleys and Goldwings that even have reverse.

As any compromise vehicle, is loses some of the original value. For instance, an extended cab pickup often has a lower max payload and a six-foot bed, both compromising the mission as a pure hauling vehicle. A minivan is often a compromise of crossing a hauling vehicle with a station-wagon. It's just that the value gained in the compromise is worth the loss. I can see tremendous value in getting out of a traffic jam by pulling onto the shoulder, extending your wings and leaving over their heads.

I absolutely agree with you that a combo vehicle that could take off on a highway shoulder would be phenomenal. I became an aviation enthusiast at the age of two after seeing a stage version of Peter Pan but no flying experience I have had since then as a licensed light plane pilot ever came up to that. Ideally there would be some kind of vertical take-off vehicle but that would require an atomic powered engine the size of a coke bottle and although that concept was popular in science fiction in the thirties and forties the reality if atomic power with its inherent dangers has put a damper on that. Who knows? Perhaps some nut in a garage will come up with a small practical Buck Rogers flying belt.

I drove to work this morning at 11 degrees and I thought about sand's personal jetpack idea.

I think I'd much rather ride in a flying motorcycle than fly a jetpack. It would be cold to fly all exposed.

Hey Hrench, in case you haven't been following it, I thought I should tell you that the Terrafugia has been successfully flight tested.

yes, I'm following it Dwane, thanks for mentioning it. I do hope they succeed, but they've made a flying car, where as I think a tandem-seat motorcycle-vehicle might be easier to get into the air.

If you watch their video, you'll notice that the front canard and rear elevator are both in nearly maximum-lift-mode for the whole flight. They have some more development to do... I'm surprised it didn't stall.

http://groups.yahoo.com/group/AeroCycle/?yguid=75402593 is a group that has had this idea for several years.