So what exactly is the purpose of carrying a rocket up to 30,000 feet and launching it? I can’t believe it’s any safer or cheaper than launching from the ground. This whole project just seems...weird.
Yeah, 60,000 ft would have been something. I suppose Spy sattelites go at about 150,000 ft, so this carries it 20% the way up using atmospheric oxygen
I am not an engineer, but I would think the first 30,000 feet are probably the most expensive.
As a former NASA engineer, I can explain.
1) A major boost from air-launching orbital rockets is lower atmospheric pressure. At 30,000 feet, you are above 75% of the atmosphere. You can generally get away with using efficient, high expansion rocket motors optimized for vacuum, such as the RL-10 or the NK-43, instead of a sea-level optimized engine, which are less efficient and more difficult to build and maintain.
2) Rapid re-usability of the launch site. If your rocket, launching vertically from a standard launch pad, is firing exhaust downward at about 6700 MPH, it requires substantial engineering to avoid damaging your launch pad (massive water sprays and exhaust redirection channels), and often it requires days (or weeks) of maintenance before the launch pad can be used again. If your rocket doesn’t rise quickly enough, it can also ‘cook’ the bottom of the rocket in the reflected exhaust. Air launch eliminates this problem completely.
3) First orbit rendezvous - If you are trying to launch your match the orbital inclination and trajectory of an existing satellite (e.x. the ISS), air-launch makes it extremely simple to move your ‘launch’ point to any needed spot to match orbits immediately. Launching from a fixed ground pad (e.x. KSC) gives you narrow launch windows that still require many orbits and a fuel-wasting course correction to achieve rendezvous.
There are other benefits, but I need to get back to work.
A huge percentage of a rocket’s fuel is used just in overcoming its inertia and getting off the ground, and then more just to reach sub-sonic speed. So instead of useful payload the bulk of the rocket weight is the fuel needed to get the thing moving. Launching from a jet that’s already going that fast changes the economics quite a lot. This behemoth of a carrier plane just increases the scale of the kinds of payloads that are already being launched in this manner.
Actually the opposite. It is financially feasible because it is a true reusable launch platform. The actual Rocket does not have to be built to carry all the Fuel needed to get it to that altitude.
The is closer to the original Space Shuttle Concept than what rolled out of NASA.
Remember when we launched an Anti Satellite Weapon from an F-15?