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Toboggans that have large stubby wings that ride in ground effect.
Would they have more or less drag than a conventional toboggan going the same speed?
ground effect boat
http://www.drivemag....ie/hof/batboat.htm
[humanzee, Nov 13 2005]
Ground Effect In Cars & Aircraft
http://en.wikipedia.../wiki/Ground_effect
[DrCurry, Nov 13 2005]
Steerable sled
http://www.amazon.c...mg=14#more-pictures
Pull the white handles. [shapu, Nov 18 2005]
[link]
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I understand skiers can go faster than terminal velocity, due to that self-same ground effect. So you could certainly go faster. Not sure about flying (gliding), though - would that just be hang-gliding with a toboggan underneath you? |
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I may be misunderstanding here. I thought ground effect as used in racing cars forced you downwards, allowing you to corner faster. Surely if you forced a toboggan downwards it would increase friction and slow you down? |
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[wags] you're thinking of downforce, (or something like that). Ground effect is what that Russian flying thing (the ekranoplan, I thnk its called) used, isn't it? |
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Ah yes. Thanks wikipaedia. It seems that standard ground effect does exactly what [humanzee] wants it to do. F1 designers also seem to have somehow inverted it for their own purposes. Doesn't seem like ground effect at all by that point, but they seem to think it is. I think the toboggan would have to be going at quite a pace before ground effect kicked in, but there's nothing wrong with that. |
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Are you also planning on adding some kind of flight controls? A rudder? Ailerons? Otherwise steering this thing would be a problem. |
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//I understand skiers can go faster than terminal velocity// Surely, "terminal" means "the fastest you can possibly go in free-fall at a given altitude"?
IIRC, speed skiing world record is a shade over 150mph, but a head-down free-fall parachutist would manage 180-200mph. Jump from high enough (e.g. Joe Kittinger) and you could easily exceed many hundreds of mph, speeds that would probably qualify as supersonic at lower altitudes. |
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There was a Japanese chap who skied down Mt Everest a few years ago, and claimed to have gone at speeds that others pointed out were in excess of terminal velocity. It prompted much debate about whether this was possible, but I cannot now locate any of it. |
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Supposedly, Joe Kittinger (I had dinner with him once, he's got some really interesting stories) did exceed the local speed of sound at one point during his legendary leap. The thing is, though, that the speed of sound is actually lower at altitude, since the air is colder. Supersonic at 100,000 feet is not supersonic at sea level. |
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Your toboggan will have more aerodynamic drag than a regular toboggan, but if you can manage to get even partially airborne, it will have much less friction drag. |
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As [NoOneYouKnow] asked, will you have any type of controls? I've been a large toboggan that nearly went airborne, and just keeping it pointed in the right direction was hard. |
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yes it would have to have some kind of flight controls or it would be pretty dangerous, perhaps airbrakes or a drag chute to slow down too. |
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I was thinking of something akin to an inflateable dinghy but wider. |
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I was wondering about the term "chap" for a Japanese guy, but in the context of skiing Mt Everest at impossible speeds, it makes sense. |
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[You would prefer I said "bloke" ? Try it with a colonial accent - "that Japanese chappie, y'know."] |
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There's an Australian bloke with one leg, who just cracked 210kmh. The world record is just over 250kmh, which is 155mph. It was on TV here at about 11:30 last night. |
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<edit> Google spat out Kittinger's top speed at 714mph = 1148.9kmh.
Fastest freefall, without special equipment is 321mph = 516.5kmh |
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There's a fair distance between those two and the fastest land speed. |
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Now that I know what ground effect is, yes, I would happily accept that on my toboggan. [+] |
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Ground effect would easily keep you just above the surface of the snow. Steering would be the biggest issue. Drogue chutes slow you down -> no ground effect. |
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Deployable handles with snow spikes ... sort of like dragging a hand behind you. Some toboggans actually use this lever action for steering. |
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air brakes, fins, and ailerons? although I suppose then you might as well just fly down in a plane. |
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[subflower]'s got the right idea. On a lot of plastic sledding devices sold to kids here in the states, there's a handle on each side. Pull the handle, it a) deforms the body of the sled a bit, increasing drag on that side, and b) deploys a little post that digs into the snow. |
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Pull both and you stop. Pull neither and you get an awesome crash into that wall of trees at the bottom of the hill. |
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{+} for both a great idea, and for getting Joe Kittinger
mentioned. [Freefall], I'm randomnly croissanting your
sole idea just for having dinner with the man. What a
legend. |
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For shits and giggles I like to show the first 20 minutes of
the second ep of the BBC's excellent "The Planets" series
(Atmospheres) to people who've not encountered Joe
"cohones of steel" Kittinger before. Brilliantly, they give
no advance warning of the freefall until it actually
happens. Works every time. |
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Bring on the sleds of doom.
Reminds me of the good old days when we could sled down giant hills at 100 kph, or ride bikes with no helmets, or play on slides made of sharp metal. |
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