h a l f b a k e r yGuitar Hero: 4'33"
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A wingsuit is a skydiving jumpsuit which is webbed
between the legs, and between the arms and torso. It
converts the skydiver into a sort of inefficient flying
squirrel.
Wingsuits are fast and, overall, have steep glide angles.
Normally, therefore, wingsuiters deploy a parachute in
order
to land.
Recently, though, at least one person has successfully
landed a wingsuit (link). This is possible partly because a
last-minute flare can trade forward speed for lift, reducing
the landing speed. And also because the landing site was a
huge tranche of cardboard boxes.
The landing is still fairly sharp, with a forward speed of
something like 30-50mph (descent speed is much less, if
the flare is timed correctly).
MaxCo. Extreme Sports, therefore, is currently enlisting
skydivers to test its skipping-stone wingsuit rig. This rig
resembles a regular wingsuit, but includes a gently curved
carapace strapped to the chest of the skydiver. With a
well-executed and well-timed flare over smooth water, a
skilled person can not only survive the landing, but can
skim across the water for well over a mile in a series of
diminishing bounces.
Wingsuit landing
http://www.youtube....watch?v=dRB-woVjlFY
[MaxwellBuchanan, Jun 20 2013]
Yves Rossy
http://www.youtube....watch?v=h4arnATc04U
Cheating by wearing jet engines. [MaxwellBuchanan, Jun 21 2013]
First confirmed climb in a wingsuit
http://www.tonywingsuits.com/
See half way down page, and links therehencefrom. [MaxwellBuchanan, Jun 21 2013]
[link]
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Yes and, besides that its dangerous, why is no one
experimenting with adding semi-rigid fins to wing suits to give
them more conttol/ slow them down? I would like to see a range
of solutions between a wing suit and a hang glider. |
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Too much wingage causes problems. It's hard
enough climbing out in a wingsuit. You can go from
a helicopter or balloon, but that limits your options. |
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I presume you've seen Yves Rossy, the human
jetplane? (Link.) |
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Beautiful. Now shouldn't there be something that is half way
between those two -- semi rigid, that would allow the flyer to
undulate for control and propulsion? |
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Maybe they could experiment with the design under water. |
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//allow the flyer to undulate for control and
propulsion?// Rossy steers by body movement -
afaik, there are no conventional control surfaces on
his wearable jet. But propulsion is a different
matter. |
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Then again, the jump partner of Corliss, Dwain Weston, was wearing a wing suit when he hit a bridge at 120 mph. |
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//stall speed of a wing suit is in ground effect.// |
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Stall speed may not be relevant. A conventional
ram-air canopy will land you at 0mph forward
speed (and a very few mph descent rate) if you
use it right, even though its best stall speed is
something like (guesstimate) 12mph. |
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Likewise, in a wingsuit it should be possible to
burn off all forward speed and convert most of it
into lift, briefly, which would offset most of the
descent speed. |
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In other words, I think it would be possible to land
a wing suit more gently than in that first link. |
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However, the big problem is timing. In a flare,
your forward and vertical speeds are changing very
fast. In fact, given that the flare is gradual, the
_rate_ of change in forward and vertical speeds is
also changing quickly. |
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This makes it very difficult to flare a wingsuit
accurately. If you flare too high, you drop like a
fully-stalled brick from your flareout point. If you
leave it too low, obviously you will have a lot of
forward and descent speed left. |
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With ram air canopies, it's a lot easier because the
pre-flare speeds are much lower; thus, you can
adjust your flare in realtime with little practice. |
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If you could get the timing perfect, I'm sure a
wingsuit landing on grass would be survivable and
even walk-away-from-able, though probably not
elegant. |
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I don't think wing suits are capable of even a moment of horizontal flight- even at maximum speed a maximum flare would just result in a slightly less steep dive. |
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That would be quite correct, [kansan101], were it
not for the fact that it's fairly clearly wrong, on
the grounds of both physics and experience. |
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If you watch the first video, his descent angle for
the last ten metres or so is something like 20
degrees; and his rate of fall during that time is
about 4m/s (using his body length as a scale bar of
2m, and estimating the height of the box pile
from that, and his fall rate from that). |
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4m/s is about 9mph vertical rate. His forward rate
is several times that, but clearly he could burn off
some more of that forward speed and convert a
proportion of it to lift, reducing both forward and
descent speeds, if it could be timed perfectly. |
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I'm not claiming that you can attain zero fall rate
(though I suspect it might be possible), nor zero
forward speed. I'm simply claiming that a wingsuit
obeys the same laws of physics as any glider,
albeit one with a high drag and low lift. As such,
forward speed can be traded for lift. |
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right up to point where the wing stalls... that being said, I eagerly await the Olympic 1000 metre Free-Fall event. |
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//right up to point where the wing stalls// That's
what we were discussing a couple of annotations
back - do try to keep up. Flareouts in ram-air
canopies, if done right, bring the forward speed to
zero, and the vertical speed to very nearly zero,
simultaneously and a few inches from the ground. |
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Oh, and apparently you can climb in a wingsuit
<link>. |
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From the data linked to from that (5th) link,
descent rate was
zero or negative (ie, climbing) for about 5
seconds, during which forward speed bled off to a
minimum of just 2kph. |
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In other words, if he had attained the near-
impossible feat of timing that flare to coincide
with his arrival at ground level, he could have
landed without spilling a glass of wine. |
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Physics. It's really jolly good. |
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// where are you reading the forward speed
from// |
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Altitude is the red line, trending down
throughout
except for the 5 second kink at about 55
seconds
into the flight. Axis is on the left in red. |
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Horizontal speed is the dark blue line which
dips
noticeably at around 55 seconds. Axis is on the
right in blue. |
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EDIT - Oh arse and bollocks. The groundspeed
curve is indeed cyan, as per caption, and
annoyingly not the dark blue curve to match
the speed axis. So yes, you're right, lowest
groundspeed is about 70kph (45mph). |
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Howevertheless, he does achieve a climb. |
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A 45mph horizontal (ie, low-descent-rate)
touchdown would work nicely with a skipping-
stone chest-guard. |
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Alternatively, if he strapped a skateboard on his
chest he could land comfortably on any long
smooth runway. |
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Yeah, but who do we know who is likely to put up
prize money for ordinary people to undertake near-
impossible feats involving speed and altitude? |
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Good point. As a statesman, I accept your kind
offer. |
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OK, the data does indicate that horizontal flight is briefly possible. |
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Back to the original idea. Stones have the stability to skip because they spin on the vertical axis when thrown. Planes can do it because they are much less dense than a human or rock (floatier) and have great big stabilizing tails. A guy in a wingsuit would really dig into the water before skipping. |
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Your guy in a wingsuit would skip exactly once, I think, and then tumble forward at 75 kph. |
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Maybe if you dropped a small sea anchor on a long bungee? |
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If he hit the water at a shallow enough angle not to
dig in (and there's no reason not to, given that brief
horizontal flight is possible as per link), and did so
fairly symmetrically, there would be little if any
spinning force imparted. |
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Moreover, a short shallow fin on the rearmost part of
the carapace would provide yaw stability. |
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Releasing a small drogue chute or a streamer just
before the flare could reduce forward speed _and_
stabilize the landing--maybe even enough for the jumper
to land on their feet, if they're a really strong sprinter. |
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Might you consider testing it out on cats first? |
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//What is the maximum speed of a high diver
anyway? // |
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I think we did this somewhere. Maximum height
seems to be about 50m which, ignoring air
resistance, gives an impact speed of about 30-
35m/s or 70mph. But then entry is with the body
perpendicular. |
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It's clearly possible to land a wingsuit on cardboard
boxes. Water would be harder (if you dug in), or
softer (if you skimmed), but definitely doable
somehow. |
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Dunno about high divers, but the theoretical maximum
speed of a _sky_ diver is terminal velocity; at 120 mph, a
diver's hands, wrists, arms, and skull would break before
the water did, no matter how perfect the form. People
who've jumped off of the Golden Gate Bridge have ended
up just as jellified as if they'd smacked into a concrete
sidewalk. |
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I imagine the same principles apply for near-horizontal
water landings as well. I've certainly seen plenty of footage
of airplanes making nice gentle glides into water, only to
cartwheel, crack up, or simply stop dead on touchdown.
There's a good reason that Captain Sully was lauded as a
hero; he wasn't the first pilot to attempt a water landing in
an airliner, he was the first to (fully) succeed. |
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I think a wingsuit diver carrying a hydrofoil would have
better luck than a skipping-stone device, but it would be
less interesting to watch (probably). |
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OK, MB, do an experiment. Go buy yourself a turkey, put it in a scaled down wingsuit with breastplate. Make a big redneck slingshot. Shoot it across your local sewage lagoon. |
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I bet you dimes to doughnuts it will tumble as soon as it touches water. |
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//I bet you dimes to doughnuts// |
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Sadly I had no access to a sewage lagoon (I believe
we send it all to Wales), so the Small Boating Lake
had to suffice. Initial results: no detectable yaw
after the first bounce. Some pitching, but almost
certainly exacerbated by the relatively round nature
of the bird. |
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Raspberry jam ones, please. |
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About 8ft in the middle, only about a foot at the
edges. Depends on how much rain there's been. |
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I'm afraid my usual cinematographer was at a party. I
did get the current Artist in Residence to turn up
and make a few sketches in realtime, but I'm not
sure the results have the clarity you're after. Last
time I hire a cubist. |
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A tumble would result. Seriously. Your guy has nothing at all to prevent it. No spin, no tail, nothing. |
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