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# sled launch base jump

shoots you 500 meters above the ground for base jump chute deployment
 (+2, -1) [vote for, against]

a long reverse slide that shoots you upwards to a height of 500 meters where you then open your base jump parachute and begin your decent.

a horizontal surface long enough to accelerate you at sub 3g threshhold to 240 miles and hour or so angled at 45 degrees should do it--getting you to 500 meters from a release point about 5 to 8 meters off the ground. at the end of sled, it angles you upwards .

this would probably be a lot cheaper to build than a 500 meter tall tower. which would cost well over 10 million dollars.

i think one of the problems may actually be chute deployment because of the necessity of holding the chute ready on the way up.which could be dangerous if it deploys prematurely.

 — teslaberry, Apr 07 2014

I like it but I think you're overestimating how high the jump needs to be. 500 meters is very high for a base jump, I would think just a couple hundred feet would be plenty. The forward velocity from the jump will allow the parachute to deploy in time.
 — DIYMatt, Apr 07 2014

 To maximise altitude you're going to want a fairly low forward speed.

 The 'chute should probably deploy before maximum altitude is reached.

 However, what with air resistance, friction etc (even with steel runners on ice) the ramp is always going to have to be greater in hight than the jump achieved as the kinetic energy at the base cannot exceed the potential energy at the top.

 For a 100m ascent, the ramp is going to have to be at least 120m high.

Building it on a hillside, like a ski jump, is the obvious solution.
 — 8th of 7, Apr 07 2014

Haven't we done this one before?
 — Alterother, Apr 07 2014

 [8th] I think he's saying that the sled is powered. Hence a "reverse slide", and "a horizontal surface long enough to accelerate you... ".

 Come on [teslaberry]. capitolization is one thing, but can't you at least do some math[s]. 240mph is fast enough to get to 587m (ignoring air resistance) if you go straight up. But at a 45 degree angle you'll only get to 293m. And ignoring air resistance while traveling 240mph is probably not a good idea.

 Why specify only 3g acceleration in the horizontal direction then have a transition from level to 45 degrees in only 8 meters of vertical distance? If your ramp has a circular arc and is 8m at the end, that corresponds to a radius of 8*sqrt(2) = 11.3m. At 107m/s, your acceleration will be over 103g. (A=v^2/r)

According to the wiki, most people can handle 20g perpendicular to the spine (either face up or face down) for 10 seconds "with cognitive facilities intact". The record is 46g peak with 1.1 second over 25g, but he suffered from vision problems after that, so lets limit it to 20g to keep this "safe". You'll need a ramp height of 41.5 meters to do 20g. But if you want to actually get to 500m altitude, you'll need to make the ramp a little taller to either handle a higher veolocity and possibly steeper launch angle.
 — scad mientist, Apr 07 2014

 //Haven't we done this one before? //

Of course, but if we keep [teslaberry] talking, he may actually try this, and we want to see it ...
 — 8th of 7, Apr 07 2014

 i did do some math wrong but, scad you are misunderstanding what i said.

 you have at least a 500 meter stretch on horizontal land with which to accelerate to the final 'cannon' speed of 240 mph or so.

 the new math makes a new assumption. you are curled up in ball and accelerated in a small capsule that allows you to experience g forces entirely in a sustained tranverse mode at 5g's ( the blood doesn't rush to your head or feet, but to the back (dorsal) section of your seated body against the backwards facing inner wall of the chamber/seat.

kinda like a roller coaster that lets you fly off at the end and gives you a base jump chute to hold on to with each ride!
 — teslaberry, Apr 08 2014

 //scad you are misunderstanding what i said//

Like I said, if everybody misunderstands you...
 — MaxwellBuchanan, Apr 08 2014

 I don't think I misunderstood. Your "clarification" sounds to me like your original description: this is rapid but reasonable horizontal acceleration to 240mph before hitting an 8m ramp that launches you in the air at a 45 degree angle.

 It sounds like you aren't aware of the fact that turing a corner (in this case from horizontal to 45 degrees up) requires acceleration, even if your speed remains the same, and if you want that to happen with a ramp that is only 8m tall, the acceleration will be 103g.

Sounds like a great thrill ride in concept, but you'll nead a larger ramp.
 — scad mientist, Apr 08 2014

And a miracle material to build it out of. Somebody wake me when we start talking about structure, I want to pick at the cracks.
 — Alterother, Apr 08 2014

 //which would cost well over 10 million dollars.//

Actually, you could calculate the cost by just asking the agent how much life insurance the rider has.
 — lurch, Apr 09 2014

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