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rocket tube

laser air heater
 
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How about a laser mounted on the tip of a rocket to heat the air. This would make the air less dense and allow the rocket to slip faster into orbit/ or use less fuel.
wjt, Feb 19 2003

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       Whats with the tube? [wjt]
skinflaps, Feb 19 2003
  

       If you're talking about lugging a payload into LEO, the atmosphere gets fairly thin quite quickly if you're heading vertically upwards, and by the time the rocket is really starting to pick up speed, aerodynamic drag is much less of an issue than at sea level.
8th of 7, Feb 19 2003
  

       Reasons why not:   

       (1) Windshear - beyond the first few inches, the air vaporized won't be the air the rocket passes through   

       (2) The vacuum window won't stay open long enough   

       (3) The heating is not effective, as laser light won't heat the air fast enough   

       (4) The apparatus would consume more energy and payload than that saved   

       (5) 8 th's point about air density   

       (6) Danger factor of a laser on the nose of the rocket   

       (7) The pressure wave gets hot from frictional forces anyway   

       (8) Low efficiency would mean the laser would heat up the rocket   

       (9) Additional complexity would increase lauch failure risk   

       (10) Cost of the laser   

       I got bored when I reached double digits, but there's plenty more.   

       Your idea does have merit, just not in the application you describe. A rocket delivery system could raise an energy weapon to a height where it could reach targets over the horizon, and by passing through less atmosphere, would be less detectable and less lossy. I believe Regan's Star Wars plan included X-Ray devices of this sort, but AFAIK they were banned under START.
FloridaManatee, Feb 19 2003
  

       Oops, looks like I scared him off....come back wjt!
FloridaManatee, Feb 19 2003
  

       Bully,...and not the 'pickled beef' variety..sheez i didn't know it meant that as well,sounds disgusting.
skinflaps, Feb 19 2003
  

       This might work slightly better if WJT would sit on the nose-cone, and breathed his favorite allergen. Forthwith he would inhale mightily (while facing skyward), then sneeze downward.
pathetic, Feb 20 2003
  

       So to get this right getting a rocket into "LEO" is all about blindly burning energy to fight for a gain against gravity not about constructing a climb by moving the stuff that is infront out of the way and building a more rigid platform below. technically the more knowledge about air the better a tread a can be designed to grip and maniulate the air.
wjt, Feb 23 2003
  

       This is a mechanism used to clear the path for particle beam weapons. So I don't think it's totally impractical. Might be useful for high speed planes, too. Perhaps the shuttle could use it to clear a path as it bangs into the atmosphere.
DrCurry, Feb 23 2003
  

       I read about an experimental craft (don't know if it was ever built) propelled by microwaves (something like this idea, but different). It accelerated much too fast to be manned, and had an estimated top speed of Mach 25 (!).   

       Anyway, the article mentioned a microwave 'aerospike' which would keep its nose from being smashed from the fast-moving air. Most fighter jets have metal aerospikes.
galukalock, Feb 23 2003
  

       I am wrong, If the space machine has enough grip in the air to control hovering and motion in the atmosphere from ground to space then an aerospike does not really matter. So engineering more controlled force is what really matters
wjt, Feb 24 2003
  

       WJT;   

       I must have misread your concept. I thought you were trying to create a vacuum pocket for a distance in front of the rocket.   

       Is this instead like the ribs on the bottom of speedboats that generate bubbles to reduce fluid friction?   

       If so, would there be a better way of reducing atmospheric pressure directly ahead of the rocket?
FloridaManatee, Feb 24 2003
  

       Initially, yes, the laser was to reduce friction infront of the rocket by making a tube of less dense air. (If the laser/beam could make a vacuum all the better)Rethinking, rocketry is about making a force in a volume that can be stood on and position held. If this can be done powerfully and cheaply, density of air/substance above is of little importance. ##maybe the laser/beam may help in the construction of fuel burn giving a more solid air brick to stand on.
wjt, Feb 25 2003
  

       How about that panel ultrasound gun thingy being used to mold the structure of the rocket flare? This would try and make stable platforms of rocket plasma to force off. A bit like blowing plasma smoke rings.
wjt, Mar 04 2003
  

       Acoustic pulsejets? While on the subject, what about shaping the rocket flare using electrostatic charge found at border of laser image, like that stungun thingie?
cloudface, Sep 01 2003
  

       Let's say you use a pulsed later and create a pocket of superheated air of low density in front of your rocket. All you've done is replace compressive heating due to collisions with the craft with laser heating, losing some efficiency in the process ;-)
mje, Oct 28 2003
  

       The concept has some merit, however I agree that ultrasound would work better. Maybe well enough to make the payload tradeoff worthwhile. New high freq work in ultra sound offers the best chance. On the other hand decent aerodynamics and a good wax job will probally work just as well. Spaceship One shows that there other ways to launch a payload.
phyrate7, Jun 25 2004
  

       I you are going supersonic (and that happens pretty quickly with a rocket) the ultrasound waves will not travel forward. I too have once read about this (russian?) craft that used a plasma and a magnetic field to overcome friction and add to the propulsion. The magnetic field would push away the ions (more precise electrons and nuclei) as they entered the field. This may be needed too for leo coilguns or railguns that have a muzzle velocity of tens of machs, but that is another matter.
nietsch, Jul 05 2004
  
      
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