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|    sci.space.tech    |    Technical and general issues related to    |    3,113 messages    |
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|    Message 2,111 of 3,113    |
|    Jeffrey Cornish to richie086@gmail.com    |
|    Re: Question about using balloons to get    |
|    02 Sep 04 14:23:31    |
      From: jcornish.nospam@nospam.speakeasy.net.retro.com              Richie,              A very good question that I will counter with another question. What       happens if that USAF Captain Kittenger stepped off the platform?              He'd fall, right? Right.              What direction?              Down, of course. It's a silly sounding question, but consider this. What       altitude would the good Captain have to be at where he _would not_ fall down       towards the Earth (removing the effects of objects such as the Moon, Sun,       and planets)              The answer is at an infinite altitude. Gravity ALWAYS attracts. The Earth       pulls on the Captain, his balloon and the atmosphere.              So lets say our good Captain is at 100,000 feet, and instead of just       dropping, he leaps out to the East at, say, 10 feet a second. If the       atmosphere didn't drag at him (as we often say in these illustrations), he'd       keep moving at 10 feet a second that direction (Good old Newton's laws say       that's whats going to happen, because during free fall, other than the       Earth's Gravity accelerating him downward, nothing is going to interfere       with his slow Eastward motion). The Captain will land some thousands of       feet to the East.              Okay, so now our Captain is back up at 100,000 feet altitude and he has a       rocket pack. The rocket will accelerate him to a final speed of 200 miles       per hour (or 288 feet per second). Turning to the East the Captain releases       himself from the balloon and ignites the rocket. The Captain will land       miles further East than he did just leaping.              If we substitute a rocket pack that can accelerate him to Mach 25 (and       increase his altitude to about 120 miles, about triple his jump off       altitude), the good Captain will be in orbit.              Basically an orbit is falling to the ground and missing, because your       horizontal velocity is high enough that by the time you would have hit the       ground you have passed around the curvature of the planet.              You could be in orbit at an altitude of 1 foot, assuming you could avoid       mountains, hills, stop signs and such.              On Earth there is a _second_ complication, the atmosphere. The atmosphere       drags on objects passing through it.              The fuel used to get to orbit used for two things, accelerating to the       velocity where the craft won't hit the ground/atmosphere (the later will       drag on the craft, slowing it so it will hit the former), and countering       losses from drag (and gravity) on the way up.              Jeffrey Cornish                            "richie086" |
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