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Pellet Stream
Machine gun vs. Cannon Ball Space Launch Scenario - http://www.massdriver.com/massdriver.html | |
Is there an aerodynamic advantage to launching a stream (series) of small hypervelocity projectiles (say 1 kg total mass - supersonic bullet shape) from Earth surface to Earth orbit vs. one large (1000 kg - spacecraft type) mass? An analogy is a Machine gun launch vs. cannon ball space launch scenario.
The idea for the machine gun stream is that the initial projectiles will reduce the drag for the following projectiles. The fire rate will have to be quite rapid! It is envisioned that the projectile motion would sort of form a boundary layer that leads to a tunnel up through the atmosphere.
Any comments on this situation would be helpful; this idea is from a few mechanical engineers, so forgive us if we are violating something obvious!
Gun Launch for Orbital Vehicles
http://www.dunnspace.com/harp.htm
[ldischler, Oct 04 2004, last modified Oct 21 2004]
[link]
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If the drag is reduced on the following projectiles and they are launched with the same initial velocities, won't they end up running into the projectiles in front of them? Or am I missing something? |
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As [ramses] said, they would run into one another. So, you might as well launch them joined to begin with. This gives you a pencil shape, which of course looks just like a rocket, as long as you add fins at the back to keep it from tumbling. (On the other hand, I suppose you could give the first one slightly more energy and the next one less and so on, but that seems rather chancy--and they would diverge, anyway.) But, a + for the idea. |
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You still end up with more overall drag, plus you still need to carry fuel to change the trajectory from a highly elliptical path which would return the projectiles to the surface to a more circular path which will carry the projectiles around the earth in stable orbit. |
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Running into each other is a problem we talked about, it might be minimized by designing the intial pellets to "burn up" so they are out of the way of the following. Can anyone think of a similar aerodynamic situation that might have been previously researched? |
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We also talked about having a 'catcher' satellite (baseball glove) in orbit to save the pellets from hitting the Earth. |
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Perhaps you could blow a hole in the atmosphere with a laser and then shoot a projectile down the resulting tube of (relative) vacuum. You’d have to keep pulsing the laser, of course, and keep your fingers crossed that the projectile would stay in the tube by deflecting off the walls. (No need to worry what happens after you get into space--Ky Michaelson didn't. And talking about baseball gloves is not going to get you funding.) |
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I have done a little work on this and uploaded it to a web site, http://www.massdriver.com/massdriver.html |
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Hey [dgerl] - no one welcomed you the the HB back in May. So welcome. The machine gun method is more analogous to a line of bike riders, each drafting off the one before - this is the aerodynamic situation which may have been researched. |
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It occurs to be that to utilize the drafting scenario, you could have one large launch, with onboard rockets spaced out to leave a trailing zone behind of low pressure air. Smaller rockets follow, drafting off the big one in front. I initially thought one might follow the big front rocket with the machine gun, however the big one needs to get up to speed, while the pellets start out at their maximum velocity. |
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Also as regards running into one another in the machine gun scenario - so what? The relative velocity will not be too great. As the front one is slowed by drag, the pursuing pellets will gradually overtake it and pile up behind. |
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Could they be made of ice and covered in a feeble biodegradable insulation ? that way they would just evaporate and the lighter parts decompose. |
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- or you could use frozen turkeys . |
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