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manofsan@yahoo.com
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 Posted: Sun Oct 02, 2005 12:46 am Post subject: Airbag/Ballute Instead of Parachute |
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If military para-drops have to occur at low altitude in order to
minimize the vulnerable parachuting phase where the parachutists are
vulnerably exposed while floating down, then what about an airbag
solution?
When you look at videos of automobile airbags inflating, they do so at
lightning speed, before your head can even hit the steering wheel or
windshield.
http://www.edinformatics.com/inventions_inventors/airbag.htm
What if you had a airbag that explosively inflated at the last moment,
to generate the drag+buoyancy to rapidly slow down your freefalling
skydiver nearer to the end of their descent? I'm picturing an airbag
that would explosively inflate with hydrogen gas for buoyancy and not
just drag. The "H-bag" would inflate below the skydiver, and not above
them, so that it could also act as a shock-absorber between the
skydiver and the ground, similar to the automobile airbag. It would
have to instantaneously inflate to a large enough size to 1)cause rapid
deceleration from buoyancy+drag and 2)create a large and safely
decelerative shock absorber between the skydiver and the ground.
I'm imagining the airbag would be stored in a device that would be
strapped on to the bottom of your feet, sort of like a snowboard. Or
else it might look like a pogo stick, and you would ride it that way.
I'm presuming that feet-first is the best way for the body to handle an
impact. I'm also presuming that the highest deceleration rate the body
can safely handle along its vertical axis is at 8 G's.
The H-bag would explosively inflate below the skydiver in the shape of
an elongated teardrop -- actually more like a clove of garlic with 4
bulging lobes. I'm imagining the extent to which each lobe is inflated
would be calibrated based on the trajectory/disposition of the
skydiver. Likewise, the altitude at which it triggers is based on the
speed of descent. As the H-bag contacts the ground, the skydiver would
plunge through the middle of it to contact the ground at reasonable
speed.
If you had to jump out of a tall building, Sept11-style, the H-bag
could work there too.
For the sake of discussion -- in a typical skydive, how large a size
would the H-bag have to inflate to, and what would be the best height
for it to trigger at, in order for you to safely reach the ground?
Any ideas?
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mike Williamson
Guest
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| Posted: Sun Oct 02, 2005 2:56 am Post subject: Re: Airbag/Ballute Instead of Parachute |
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[email]manofsan (AT) yahoo (DOT) com[/email] wrote:
| Quote: | If military para-drops have to occur at low altitude in order to
minimize the vulnerable parachuting phase where the parachutists are
vulnerably exposed while floating down, then what about an airbag
solution?
When you look at videos of automobile airbags inflating, they do so at
lightning speed, before your head can even hit the steering wheel or
windshield.
http://www.edinformatics.com/inventions_inventors/airbag.htm
What if you had a airbag that explosively inflated at the last moment,
to generate the drag+buoyancy to rapidly slow down your freefalling
skydiver nearer to the end of their descent? I'm picturing an airbag
that would explosively inflate with hydrogen gas for buoyancy and not
just drag. The "H-bag" would inflate below the skydiver, and not above
them, so that it could also act as a shock-absorber between the
skydiver and the ground, similar to the automobile airbag. It would
have to instantaneously inflate to a large enough size to 1)cause rapid
deceleration from buoyancy+drag and 2)create a large and safely
decelerative shock absorber between the skydiver and the ground.
I'm imagining the airbag would be stored in a device that would be
strapped on to the bottom of your feet, sort of like a snowboard. Or
else it might look like a pogo stick, and you would ride it that way.
I'm presuming that feet-first is the best way for the body to handle an
impact. I'm also presuming that the highest deceleration rate the body
can safely handle along its vertical axis is at 8 G's.
The H-bag would explosively inflate below the skydiver in the shape of
an elongated teardrop -- actually more like a clove of garlic with 4
bulging lobes. I'm imagining the extent to which each lobe is inflated
would be calibrated based on the trajectory/disposition of the
skydiver. Likewise, the altitude at which it triggers is based on the
speed of descent. As the H-bag contacts the ground, the skydiver would
plunge through the middle of it to contact the ground at reasonable
speed.
If you had to jump out of a tall building, Sept11-style, the H-bag
could work there too.
For the sake of discussion -- in a typical skydive, how large a size
would the H-bag have to inflate to, and what would be the best height
for it to trigger at, in order for you to safely reach the ground?
Any ideas?
|
Several ideas, none of which are conducive to your idea working:
1- A person not well trained and practiced in free-fall parachuting
would only be correctly oriented prior to impact due to sheer chance.
If you are below the airbag when it deploys, you'll be cushioning
IT'S impact rather than the other way around.
2- The best way to take a deceleration in not in the vertical axis,
but fore/aft (with proper distribution of forces). While the
backbone can take 8 G's or even more, this won't happen if you
aren't in a good position, and in freefall, you're virtually
guaranteed that you won't be in a good position to take the
acceleration. You'd also tend to break your legs and/or
seriously screw up your knees and ankles landing on an airbag that way
if your don't just plain kill yourself.
3- How do you ensure correct deployment altitude of the airbag? You
want to deploy the device immediately before impact, which gives you
no margin for error- if it fails to inflate, you aren't going to have
the time to deploy a reserve, or anything similar.
4- given the necessary size of the airbag, the device is going to
be significantly bulkier than a parachute, resulting in fewer troops
able to be carried by a given transport, and quite possibly resulting
in slower exit from the aircraft (not as many troops exiting in a
given time).
5- The troops will be carrying a very high horizontal velocity at the
time of airbag deployment, and subsequently on impact. This means that
they are going to hit the ground (which may well be uneven and/or
strewn with debris. You have a good chance of the bag not staying
stable, resulting in the bag/body tumbling and/or rolling
before coming to a stop. Additionally, if you tear out the bottom
of the bag, it won't provide protection for the rest of the ride
in any case.
All in all, you have a heavier, bulkier, more complex system that
is less likely to work safely than the existing system which is
already in place. If you want simply to reduce the time spent
vulnerable to fire, you could simply delay opening a conventional
parachute, which would leave you with problem 3 above but not
introduce any new ones, although low altitude drops using static
lines are already intended to minimize both the vulnerable time
spent under a chute and drift away from the DZ due to winds, etc.
Mike
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John Gentry
Guest
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| Posted: Sun Oct 02, 2005 3:32 am Post subject: Re: Airbag/Ballute Instead of Parachute |
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Dude, what have you been smoking?
"manofsan (AT) yahoo (DOT) com" <manofsan (AT) gmail (DOT) com> wrote
| Quote: | If military para-drops have to occur at low altitude in order to
minimize the vulnerable parachuting phase where the parachutists are
vulnerably exposed while floating down, then what about an airbag
solution?
When you look at videos of automobile airbags inflating, they do so at
lightning speed, before your head can even hit the steering wheel or
windshield.
http://www.edinformatics.com/inventions_inventors/airbag.htm
What if you had a airbag that explosively inflated at the last moment,
to generate the drag+buoyancy to rapidly slow down your freefalling
skydiver nearer to the end of their descent? I'm picturing an airbag
that would explosively inflate with hydrogen gas for buoyancy and not
just drag. The "H-bag" would inflate below the skydiver, and not above
them, so that it could also act as a shock-absorber between the
skydiver and the ground, similar to the automobile airbag. It would
have to instantaneously inflate to a large enough size to 1)cause rapid
deceleration from buoyancy+drag and 2)create a large and safely
decelerative shock absorber between the skydiver and the ground.
I'm imagining the airbag would be stored in a device that would be
strapped on to the bottom of your feet, sort of like a snowboard. Or
else it might look like a pogo stick, and you would ride it that way.
I'm presuming that feet-first is the best way for the body to handle an
impact. I'm also presuming that the highest deceleration rate the body
can safely handle along its vertical axis is at 8 G's.
The H-bag would explosively inflate below the skydiver in the shape of
an elongated teardrop -- actually more like a clove of garlic with 4
bulging lobes. I'm imagining the extent to which each lobe is inflated
would be calibrated based on the trajectory/disposition of the
skydiver. Likewise, the altitude at which it triggers is based on the
speed of descent. As the H-bag contacts the ground, the skydiver would
plunge through the middle of it to contact the ground at reasonable
speed.
If you had to jump out of a tall building, Sept11-style, the H-bag
could work there too.
For the sake of discussion -- in a typical skydive, how large a size
would the H-bag have to inflate to, and what would be the best height
for it to trigger at, in order for you to safely reach the ground?
Any ideas?
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tom
Guest
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| Posted: Sun Oct 02, 2005 4:03 am Post subject: Re: Airbag/Ballute Instead of Parachute |
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Well thought out, Mike. Tom
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manofsan@yahoo.com
Guest
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| Posted: Sun Oct 02, 2005 4:06 am Post subject: Re: Airbag/Ballute Instead of Parachute |
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Alright, suppose we increase aerial drag by making our H-bag ballute
more in the shape of a mushroom/toadstool? The top of the toadstool
would catch more passing air, so that the increased aerial drag would
reduce horizontal and vertical speed. Meanwhile the lower part of the
toadstool would be tougher, and able to take the main shock of
touchdown.
The skydiver would then fall in a spread-eagle position, and would be
resting on the top of the toadstool when it hit the ground. He might
need some kind of neckbrace however. The lower part of the toadstool
would be filled with bubbles/pockets which would burst upon touchdown,
using cell-collapse effect to help dissipate energy of impact, rather
than causing the whole thing to bounce and roll over.
You would have comparable drag to a parachute, but
1) you would also benefit from H2 buoyancy
2) you would be able to hit the ground at higher velocity due to airbag
protection
3)because it inflates, there's less chance of fouling as with parachute
lines, and you don't have to worry as much about incorrect packing
4)you would wear it like a pancho/windbreaker
It could use electronics, such as laser rangefinder to track descent
trajectory and trigger appropriately. The electronics would have their
own built-in redundancy.
How about that?
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Keith W
Guest
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| Posted: Sun Oct 02, 2005 8:20 am Post subject: Re: Airbag/Ballute Instead of Parachute |
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"manofsan (AT) yahoo (DOT) com" <manofsan (AT) gmail (DOT) com> wrote
| Quote: | Alright, suppose we increase aerial drag by making our H-bag ballute
more in the shape of a mushroom/toadstool? The top of the toadstool
would catch more passing air, so that the increased aerial drag would
reduce horizontal and vertical speed. Meanwhile the lower part of the
toadstool would be tougher, and able to take the main shock of
touchdown.
The skydiver would then fall in a spread-eagle position, and would be
resting on the top of the toadstool when it hit the ground. He might
need some kind of neckbrace however. The lower part of the toadstool
would be filled with bubbles/pockets which would burst upon touchdown,
using cell-collapse effect to help dissipate energy of impact, rather
than causing the whole thing to bounce and roll over.
|
It wouldnt help much
Assuming your airbag is 2ft thick and impact velocity is circa 120mph
and final velocity is 0 then acceleration is given by v*v= 2as
thus final acceleration (a) = (v*v)/2 *2
where v=velocity (176 ft/s)
a= (176*176)/4=7744 ft/sec2= 242 gravities
Human beings dont stand up to such accelerations at all well.
The NHTSA standard for a sudden impact acceleration
on a human that would cause severe injury or death is
75 g's for a "50th percentile male", 65 g's for a
"50th percentile female", and 50 g's for a "50th percentile child"
Keith
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tscottme
Guest
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| Posted: Sun Oct 02, 2005 9:02 am Post subject: Re: Airbag/Ballute Instead of Parachute |
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"manofsan (AT) yahoo (DOT) com" <manofsan (AT) gmail (DOT) com> wrote
| Quote: | If military para-drops have to occur at low altitude in order to
minimize the vulnerable parachuting phase where the parachutists are
vulnerably exposed while floating down, then what about an airbag
solution?
|
My skydiving experience is limited to static-line jumps from small civilian
aircraft. However my friend in college was a member of US 82nd Airborne and
had numeorus jumps. He indicated, and I've since confirmed this with
reports in Aviation Week magazine, that if commanders are worried about
dropping troops and having them shot at while under canopy, they simply drop
the troops very low. The paratrooper indicated they had numerous drops that
were so low they barely had time to swing under the canopy before they hit
the dirt. He explained it as opening shock, swing, swing, thud. AW&ST
reporting indicated the lowest successful opening of a combat-equipped
soldier was 300 feet above ground. You can make up for very low altitude
drop by increasing the airspeed at which you deploy the troops.
I don't recall a lot of paratroop drops while under fire. Sure they are
capable of dropping into a hot drop zone and fighting immediately.
Typically they are dropped in conditions less hostile than seen in the war
movies.
--
Scott
By pretending that all cultures are equal, multiculturalism doesn't
'preserve' traditional cultures so much as sustain them in an artificial
state that ensures they'll develop bizarre pathologies and mutate into some
freakish hybrid of the worst of both worlds.
Mark Steyn
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manofsan@yahoo.com
Guest
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| Posted: Sun Oct 02, 2005 2:25 pm Post subject: Re: Airbag/Ballute Instead of Parachute |
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well, like I said, it's not supposed to deploy exactly when you hit the
ground, just much lower than when you'd deploy a parachute.
Suppose the H-bag deployed at 30 to 50 feet above the ground, instead
of 2 feet away from the ground? Electronics would judge the best
distance for deployment, based on trajectory/velocity/disposition.
Lying on a gasbag could be less stressful on the body than being jerked
by a parachute harness.
Perhaps the venting gas from the H-bag could also make use of
ground-effect for further braking ability.
ascii art of toadstool cross-sectional shape:
_______ _______
/ _____ o--
Also consider that parachutes are more visible and thus are a big
giveaway that a para-drop is occurring. If you have something that
deploys at lower altitude, it is less visible above the horizon.
Also note that the H-bag is not intended to be reusable, like a
parachute is.
It's supposed to tossed away disposably.
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manofsan@yahoo.com
Guest
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| Posted: Sun Oct 02, 2005 3:01 pm Post subject: Re: Airbag/Ballute Instead of Parachute |
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aargh, dang ascii art -- font reformatted -- hopefully this is better:
_______ _______
/ _____ o--
The o-/-< is of course the little man
But maybe this idea could be used for Martian lander probes too.
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Peter Twydell
Guest
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| Posted: Sun Oct 02, 2005 5:40 pm Post subject: Re: Airbag/Ballute Instead of Parachute |
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In message <1128213960.455028.238250 (AT) g44g2000cwa (DOT) googlegroups.com>,
"manofsan (AT) yahoo (DOT) com" <manofsan (AT) gmail (DOT) com> writes
| Quote: | If military para-drops have to occur at low altitude in order to
minimize the vulnerable parachuting phase where the parachutists are
vulnerably exposed while floating down, then what about an airbag
solution?
When you look at videos of automobile airbags inflating, they do so at
lightning speed, before your head can even hit the steering wheel or
windshield.
http://www.edinformatics.com/inventions_inventors/airbag.htm
What if you had a airbag that explosively inflated at the last moment,
to generate the drag+buoyancy to rapidly slow down your freefalling
skydiver nearer to the end of their descent? I'm picturing an airbag
|
<snip painful-sounding proposition>
1. Why not fit the jumper with wings and a tailplane? Maybe little
wheels, too.
2. Use the blind jumper's technique: jump with a dog and pull the
ripcord when the lead goes slack.
--
Peter
Ying tong iddle-i po!
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Keith W
Guest
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| Posted: Sun Oct 02, 2005 5:49 pm Post subject: Re: Airbag/Ballute Instead of Parachute |
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"manofsan (AT) yahoo (DOT) com" <manofsan (AT) gmail (DOT) com> wrote
| Quote: | well, like I said, it's not supposed to deploy exactly when you hit the
ground, just much lower than when you'd deploy a parachute.
Suppose the H-bag deployed at 30 to 50 feet above the ground, instead
of 2 feet away from the ground?
|
Assuming a 2 ft thick pad and a max acceleration of 8 gees
the max terminal velocity at impact must be no more than
30 ft/sec
Now terminal velocity is around 224 ft/sec so that means you need
enough braking to lose 194 ft /sec in 50 ft
v*v=u*u + 2as
224*224=30*30 + 2*a*50
so we get
a= (50176-900)/100
a= 54 ft/sec2
That requires a huge braking force calculated by the formula
F=Ma
The caclulation of which I leave as an exercise for the reader
suffice it to say thats it more than is reasonably achievable
in your design.
Keith
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george
Guest
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| Posted: Sun Oct 02, 2005 7:45 pm Post subject: Re: Airbag/Ballute Instead of Parachute |
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tscottme wrote:
| Quote: | "manofsan (AT) yahoo (DOT) com" <manofsan (AT) gmail (DOT) com> wrote in message
news:1128213960.455028.238250 (AT) g44g2000cwa (DOT) googlegroups.com...
If military para-drops have to occur at low altitude in order to
minimize the vulnerable parachuting phase where the parachutists are
vulnerably exposed while floating down, then what about an airbag
solution?
My skydiving experience is limited to static-line jumps from small civilian
aircraft. However my friend in college was a member of US 82nd Airborne and
had numeorus jumps. He indicated, and I've since confirmed this with
reports in Aviation Week magazine, that if commanders are worried about
dropping troops and having them shot at while under canopy, they simply drop
the troops very low. The paratrooper indicated they had numerous drops that
were so low they barely had time to swing under the canopy before they hit
the dirt. He explained it as opening shock, swing, swing, thud. AW&ST
reporting indicated the lowest successful opening of a combat-equipped
soldier was 300 feet above ground. You can make up for very low altitude
drop by increasing the airspeed at which you deploy the troops.
I don't recall a lot of paratroop drops while under fire. Sure they are
capable of dropping into a hot drop zone and fighting immediately.
Typically they are dropped in conditions less hostile than seen in the war
movies.
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manofsan@yahoo.com
Guest
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| Posted: Sun Oct 02, 2005 7:50 pm Post subject: Re: Airbag/Ballute Instead of Parachute |
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Alright, what about a distance of 100 feet -- which is still
substantially lower than what you can get with a parachute -- and an
airbag that's 4 feet thick?
You could allow for a short-term peak deceleration rate of 12 G's,
since you're spread-eagled on an airbag. It could still be more
comfortable than a parachute.
What's the peak G-forces felt by a parachutist, anyway?
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Keith W
Guest
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| Posted: Sun Oct 02, 2005 10:45 pm Post subject: Re: Airbag/Ballute Instead of Parachute |
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"manofsan (AT) yahoo (DOT) com" <manofsan (AT) gmail (DOT) com> wrote
| Quote: | Alright, what about a distance of 100 feet -- which is still
substantially lower than what you can get with a parachute -- and an
airbag that's 4 feet thick?
|
Do the math, I have given you the equations
Keith
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Mike Spurgeon
Guest
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| Posted: Sun Oct 02, 2005 10:52 pm Post subject: Re: Airbag/Ballute Instead of Parachute |
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[email]manofsan (AT) yahoo (DOT) com[/email] wrote:
| Quote: | Alright, what about a distance of 100 feet -- which is still
substantially lower than what you can get with a parachute -- and an
airbag that's 4 feet thick?
|
Move the goal posts all you want.
It's not going to work.
Successfully...
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