Gilbert Posted October 10, 2007 Share Posted October 10, 2007 Big Cojones Quote Link to comment Share on other sites More sharing options...
Klipsched with Yamahas Posted October 10, 2007 Share Posted October 10, 2007 Hey Gil, they've perfected the catapult techniques on the Eastern Shore Pumkin' Chunkin': http://news.nationalgeographic.com/news/2005/10/1026_051026_pumpkintoss.html Us Eastern Shore rednecks will eventually try a human NO DOUBT[] Quote Link to comment Share on other sites More sharing options...
Piranha Posted October 10, 2007 Share Posted October 10, 2007 Looks like fun. Where do I sign up? Quote Link to comment Share on other sites More sharing options...
fini Posted October 10, 2007 Share Posted October 10, 2007 I'd be worried about getting a limb (or my head) stuck in the rubber bands at take-off. I mean, it'd be bad enough getting your leg ripped off, but trying to land on one good one and a fresh stump? Quote Link to comment Share on other sites More sharing options...
oldbuckster Posted October 11, 2007 Share Posted October 11, 2007 If you had the Cojones before launch, you might not have them after launch.........................EH ?????? Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted October 11, 2007 Share Posted October 11, 2007 Its not my lack of large and hairy cojones, but my brain that would get in the way. Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted October 11, 2007 Share Posted October 11, 2007 looks cool, where do i sign up? Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted October 11, 2007 Share Posted October 11, 2007 I wonder how many G's you'd pull on that? Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted October 11, 2007 Share Posted October 11, 2007 I would definatly pull my groin on that, so I think its just one G. Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted October 11, 2007 Share Posted October 11, 2007 I wonder how many G's you'd pull on that? since all the force is within the time of the rubber band, the energy is dissipating as you go further up.... the most g force would be the initial. Since he pulled it off safely it seems to be realm of capable. Sustained g's like airplanes and race cars are another matter since you can spend more then 30 seconds in a maneuver. I remember the first safety rocket chairs for airplanes were pneumatic and broke the pilot's back due to the initial g's. Quote Link to comment Share on other sites More sharing options...
alliclaytor Posted October 11, 2007 Share Posted October 11, 2007 It's been a while since I took physics...but here we go. I can't answer with any certainty so I will give the equations and let you guys make your assumptions to plug and chug. Also...I am bored so don't ask me why I am not doing something more productive with my time. Elastic bands are often assumed to be similar to springs in simple modeling purposes with nearly linear acceleration during its use so long as it is not under tensile strength beyond its capabilities (perhaps not the case in shooting someone into the air...not so safe.) So Hooke's Law applies. If you can find the k value of the elastic bands, and the distance it was in contact with the seat you can use this. Force = k * distance traveled under guidance of elastic bands Acceleration = Force / Mass (of the guy) If you could estimate how high he went you could go this route: Velocity leaving spring (meters/sec) = (final height (meters) + (.5 * 9.81 * time in air ^2))/ time in air Acceleration = Velocity leaving spring/Time in spring -OR- Velocity leaving spring (meters/sec) = sqrt(19.62(max height-height leaving unit)) Acceleration = Velocity leaving spring/Time in spring I think there may be some other variations on these...but I don't know of a way of solving the equations with so many unknowns. There are not even enough different formulas that I know of to be able to solve simultaneously without performing redundancies and getting nowhere. But who cares it's just a movie! Quote Link to comment Share on other sites More sharing options...
Moderators dtel Posted October 11, 2007 Moderators Share Posted October 11, 2007 NO thanks, I would jump off a building with that parachute before doing that ! Quote Link to comment Share on other sites More sharing options...
m00n Posted October 12, 2007 Share Posted October 12, 2007 Big Cojones OMG yes, I would so do that... That looks like an incredible amount of fun. Sure, you gotta take your man panties off after, but... oh yeah. Quote Link to comment Share on other sites More sharing options...
oscarsear Posted October 13, 2007 Share Posted October 13, 2007 Don't know if it's big cojones you need or the lack of grey matter. They mustered a lot of energy to propel that guy that high that fast. Had any of a number of things gone awry he'd have been toast. Consider what would have happened if he'd launched at even a slight angle. He'd have gone far but not high. Not high enough to get any use from that parachute. I'd wager that he ruptured some vessels when he took off as it was. Quote Link to comment Share on other sites More sharing options...
DrWho Posted October 13, 2007 Share Posted October 13, 2007 Isn't the minimum altitude of parachute deployment for a successful landing something around 2000 feet? From the video, it looks like it took him about 5 seconds to reach his full height before he started falling and then deployed the chute. If we figure a minimum of 2000 feet for the crest of his height, then we can figure how fast he was going at the end of his launch from the catapult. We can also get an idea of how long he was in the rubber band which would be able to provide an average acceleration over that distance and thus the number of G's being encountered. However, it's late and I'm too tired to plug through the equations. But for what it's worth, I doubt they used a spring constant on the bungee cords that would exceed the forces that the body could handle. At that point, it's merely a matter of determining how far the person needs to be accelerated in order to keep it safe. I really see no reason why this couldn't be done in a manner that would make it possible. The landing looks a bit rough though... Quote Link to comment Share on other sites More sharing options...
Gilbert Posted October 13, 2007 Author Share Posted October 13, 2007 Isn't the minimum altitude of parachute deployment for a successful landing something around 2000 feet? From the video, it looks like it took him about 5 seconds to reach his full height before he started falling and then deployed the chute. If we figure a minimum of 2000 feet for the crest of his height, then we can figure how fast he was going at the end of his launch from the catapult. We can also get an idea of how long he was in the rubber band which would be able to provide an average acceleration over that distance and thus the number of G's being encountered. However, it's late and I'm too tired to plug through the equations. But for what it's worth, I doubt they used a spring constant on the bungee cords that would exceed the forces that the body could handle. At that point, it's merely a matter of determining how far the person needs to be accelerated in order to keep it safe. I really see no reason why this couldn't be done in a manner that would make it possible. The landing looks a bit rough though... Common sense should tell you there's no F'ing way in hell that contraption is going to shoot a man 2000 ft up into the air, I don't care if he only weights 50 lbs.,...... aint gonna happen.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> The answer is a painfully simple one, and the analytical procedure should have been introduced at the end of your statics class during your first semester as a freshman engineering student. Stop trying to toot your horn and make it out like it's some big analytical challenge, it's not. It is a painfully simple kinematics problem. If your anywhere beyond a 2nd semester of engineering, then you should be able to solve this in less than 5 min. and with only 2 necessary engineering assumption. This is kids stuff for an engineering student, let along an impaticent old fart that's been out of school for almost 20yrs. Sorry, but repeat offender braggarts get my goat. Quote Link to comment Share on other sites More sharing options...
DrWho Posted October 14, 2007 Share Posted October 14, 2007 Yep [Y] Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted October 14, 2007 Share Posted October 14, 2007 2000 feet is when you reach terminal velocity falling.... which he never did.... he opened his chute right after he reached maximum velocity negating the need for 2000 feet of clearance. Its almost like cliff or building diving. Where you open your chute nearly immediately after you fall so you never obtain terminal velocity thus making it safer (possible) to parachute down. Quote Link to comment Share on other sites More sharing options...
Groomlakearea51 Posted October 15, 2007 Share Posted October 15, 2007 Isn't the minimum altitude of parachute deployment for a successful landing something around 2000 feet? Static line jumps (that's where you are hooked up in the aircraft and when you head out the ramp, the chute deployment strap pulls the chute out when it reaches the end of the strap), and can be quite low. Combat jumps can be between 750 and 1000 feet, depending on the conditions. A tactical static line drop over the water can be as low as 500 feet (done one back in the day off Roosey Roads in Puerto Rico). As I recall, almost within about 1-2 seconds of the canopy deploying, we hit the water. Wild ride.... Otherwise, about 900 feet is the safety limit for a free jump, and the jumpers better have it together.... That means as soon as you "hit the wind", you'd better be pulling the ring.... There is no room for error below about 750-850'. Base jumpers have done jumps at 550-850, but they are pulling the ring pretty much as they are clear of the bridge/ building. Parachuting is one of those sports that you are presumed dead unless you do something.... I'm prohibited by my agency from engaging in any parachuting "activity" under penalty of (1) no insurance, and (2) instant dismissal for violating policy. That should tell you something.... Hooyah!! 24 months to go until final retirement, my freefall chute is packed and ready, and I'm headed to the airport.... Gonna' jump 10,000 feet off the coast, fall as long as I can (to about 1500 feet), and land on the beach. Quote Link to comment Share on other sites More sharing options...
Tracking Angle Posted October 15, 2007 Share Posted October 15, 2007 "Hooyah!! 24 months to go until final retirement, my freefall chute is packed and ready, and I'm headed to the airport.... Gonna' jump 10,000 feet off the coast, fall as long as I can (to about 1500 feet), and land on the beach." THAT--is so cool! Quote Link to comment Share on other sites More sharing options...
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