h a l f b a k e r yPoof of concept
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A small fixed-wing aerocraft, preferrably a Cessna, and a bungee rope. The machine flies at a good altitude, and people bungee-jump from it, with ropes attached to specially reinforced rails.
Once they have all stopped bouncing, they can either just swing around while getting dragged by an aerocraft
at around 200 mph*, or they can detach from it and parasail away.
* Terminal velocity of a human being is about 300 mph, though people have withstood Mach1+ and higher.
Helicopter bungee is well established
http://seven.com.au/sunrise/grantsjump
[ConsulFlaminicus, Mar 21 2006]
Zorb jumping
Skydiving_20spheres
A better idea [ConsulFlaminicus, Mar 21 2006]
A cool Ballistics simulator
http://www.cs.utah..../Cannon/Cannon.html
[jhomrighaus, Mar 21 2006]
Science Content
http://www.glenbroo...ss/1DKin/U1L5d.html
An easy to understand primer on gravity [jhomrighaus, Mar 21 2006]
[link]
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Preferably a Cessna? Why? |
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[DrC] I just like "aerocraft". It's technically correct, and it looks better than "aircraft" |
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[bristolz] Cheap, easily maintained, and not so fast that your eyes pop out from the wind. |
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IHmm. [ConsulFlamencus] I never knew that heli-jumps were in existence. But they are, so I've changed it to "fixed-wing", as that was my original emphasis, and helicopter was just an add-on. |
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Isn't the whole fun of bungee jumping the fact you are simulating freefall? |
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DesertFox: okay, we'll allow for poetic license. |
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This seems a little odd. Maybe it's just me but if you are tied behind a plane moving at "200mph" or 320km/h I do not believe you will fall very far (fall rate from rest at 9.8 meters per second squared) so depending on the length of the bungee cord (not provided) with the plane moving forward you will probably reach the end of the bungee cord after falling only a few meters before causing you to be dragged directly behind the plane. This of course would negate the fact that it was a bungee cord as it would probably never reach a point where the elasticity of the bungee was grater than the force of the plane moving forward so really all you are suggesting is jump out of a plane with a rope tied around your legs. |
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Cessna builds the fastest civilian [aero]craft available, the Citation X. It's easily maintained but not so cheap, unless compared to a GV. |
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That's looking a lot like do-it-yourself moderation, [DrC]. I thought we had an agreement. |
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Urm, [Braindead] Have you ever taken high school physics? Of course you wouldn't fall straight down. You would fall at an angle. Gravity is, after all, just acceleration towards mass. Thing paddleball downwards, at an angle. It works the same way. |
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[bris] I'm thinking the smaller, not so horrible expensive, propeller-propelled ones with the wing attacked at the top of the cabin. Though doing this in a jet, now... |
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Desertfox //Urm, [Braindead] Have you ever taken high school physics? Of course you wouldn't fall straight down. You would fall at an angle. Gravity is, after all, just acceleration towards mass. Thing paddleball downwards, at an angle. It works the same way.// |
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I guess I am ignorant and must bow to your wisdom please explain more how "I will fall at an angle" when I drop from the plane like the paddleball. This math stuff (what did you call it physics) is obviously to confusing for me. |
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[DesertFox] When talking about any sort of extreme sports, you should always look to New Zealand. If they haven't thought about it and done it then the strong likelihood is that they have thought about and understood it to be impossible / crap / against the laws of physics.. and bear in mind that 'impossible' to a Kiwi extreme sportsperson is somewhat of a more flexible concept than 'impossible' to any sane person. |
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In this case, my suspicion is that the forces on the aircraft as the bungee tightened would severely effect its control. Aviation is one of those super-regulated areas for safety, and this would be way outside the envelope :) |
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[Braindead], think about when something is dropped out of a car window. The person will be travelling horizontally at the same speed as the plane immediately after disembarking. It is air resistance that would slow the person down considerably. But if the plane was decelerating for example, it might just be possible. |
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[Braindead] There are several different acceleration and static velocity vectors that come into play here, First the gravitational Vector which is accelerating the diver towards the earth at about 9.8m/s squared, next you have the forward velocity vector from the motion of the plane. You then have a drag vector acting at a right angle to the center of the divers mass that is determined based on the coefficient of friction of the divers body and clothing. There are also small vectors that are not significant at this point. |
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As the diver leaps from the plane he has the full velocity imparted on him by the plane. he immediately begins to accelerate towards the earth as well. At the same moment the drag vector begins to act on him as well. If he is moving at say 50m/s when he leaves the plane and the drag vector causes a 10m/ss acceleration opposite of his direction of travel it will take him about 5 sec to reach a point at which he is travelling in a roughly vertical path. In that same period he would have travelled downward almost 250ft and be travelling almost 150 mph taking into account the increasing friction. If the bungie is 100ft long at full stretch he will hit the end of his cord in about 5 sec. However the plane would have travelled over 700 feet meaning that about 3.5 seconds after leaving the plane he would have fallen about 50-60 feet and be yanked back up by the plane pulling him by his bungie cord. |
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The shape of this trajectory would look something like this: |
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____________________________ |
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Not sure if this would really be worth the effort as you could just jump off the plane and have a much more fulfilling ride. |
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Velocity of plane is constant at 200mph (stated) = 322kph or 89 meters per second
Planes horizontal altitude remains constant
Gravity is constant 9.8m/s/s
Terminal velocity of bungee jumper 56m/s (we will never reach it)
Length of Bungee cord fully stretched 100 meters |
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Time for cord to be fully stretched ignoring gravity and free fall of jumped best case is 100/98=1.2 seconds. So in just over a second a person will be dragged directly horizontal to the plane. OK you could take a bungee cord 1000 meters long but that would extend your time to a whole 10.2 seconds if you ignore the distance you will fall relative to the initial position of the plane. |
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if one assumes a frictional loss of 9.8m/s and gravity is 9.8m/s then the diver would reach the end of his 100 meter cord at about 4 seconds after leaving the plane. He would be about 78 meters behind the plane and about 78 meters below it. if you traced his path from his jump point in space it would scribe an arch in the direction of travel of the plane. If no frictional loss then he would reach end of cord about 4.5 seconds after leaving the plane, for a 1000 meter cord that would take about about 14.2 seconds. |
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I did not bother taking into account the horizontal velocity of the jumper relative the earth as there were so many other variables but I do agree you will begin to immediately decelerate horizontally and accelerate vertically when you first exit the plane. |
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Using pythag to do a quick check of your math’s we are out by about 10 meters (about 70 meters horizontal and vertical would work) but I am not sure how you derived a 9.8ms horizontal deceleration. |
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So if we take a real quick look at the problem we would also need to include wind resistance, slip stream and the fact that the bungee cord length "fully stretched" was 100m. So the question we also need to address what point did the actual bungee cord result in you changing from horizontal deceleration and a vertical acceleration position to a horizontal acceleration and vertical deceleration. (50m’s ??). So now we are moving in an upwards direction and accelerating horizontally back towards the original velocity of the plane as the cord begins to stretch. |
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So really if the un stretched length of cord is 50m the maximum fall distance would be closer to 35m before you would begin to climb upwards and end up directly behind the plane about 2 seconds after you jump out and eventually end up somewhere between 50 and 100m behind the plane as I would assume drag would counteract any potential energy stored in the cord. |
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I agree with the last assertion.I think you would always be slightly below the plane once a static position was reached. As to the 9.8m/s Horizontal it was simply a convieninet number to make the calculation easy. |
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I suspect that once all is said and done it would probably look a lot like a paratrooper jumping out of a plane.except that no parachute just slow to a stop relative to the plane slightly below and around 70 to 90 meters behind. |
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Now off to search out information on drag coefficinets of persons falling out of airplanes. |
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make sure you won't hit the plane when you bounce back... |
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