Launching Spacecraft From Aircraft

Embedded Geek writes: "New Scientist has an article on a proposed launch scheme named 'Bladerunner' (presumably, someone is a P.K. Dick fan) that would use a pneumatic launcher to shove a launch vehicle out the back of a military transport aircraft at high altitude (40,000 feet/12,000 meters). As with all the new systems (such as this one) the goal is to reduce launch costs to more reasonable levels (to about $6K/kilo from today's $11-44K). An existing Pegasus system uses dedicated B-52s with the vehicle slung underneath, but Bladerunner would be an improvement by not requiring dedicated planes (the launcher could be set up on a transport in 24 hours) and also could accomodate larger vehicles (since it wouldn't be slung underneath)."

Comments

Re:do the math.

[FTL]

> In any case the energy savings by lifting the payload to 20km are minimal at best. Most of the advantage comes from being weather independant, due to being above the clouds.

Nice point. However, I'd think that there are more important saveings than a 20km lift and weather independance:

• Equator. You get to launch exactly on the equator, instead of having to burn fuel in dog-leg maneuvers to get there.
• Horizontal speed. An old German V2 can get to space, but it can't get to orbit. A launch is a little bit of up, and a whole lot of sideways. If you dump the rocket out of the plane while traveling at Mach 0.75, that's 3% of your velocity taken care of.
• Engines. The real reason rockets stage is to swap out engine nozels. The bells that work at sealevel are ill-suited to vacuum operation. By launching above most of the atmosphere you can just use a single stage.
• Friction. A good portion (numbers anyone?) of the energy of a lunch is devoted to plowing through the air. Something that's not an issue when you start 20km up.