Comment by kitd
9 hours ago
Interesting post. I'd never thought of it that way. Not consciously anyway.
Might that make an air-launched system more reliable? Even if it's less efficient, the TCO would be lower using a winged system for the initial phases of launch.
It wouldn’t help much, sadly. Getting to orbit is about speed, not height — you need 27000 kph to get to orbit, and having an air launched platform would shave off 1k kph off it at most, perhaps 5k with some insane hypersonic engineering.
Main advantage of air launch is that you can better match your target inclination or perhaps even orbit timing - just drop the rocket at the right time in the right direction over the ocean. With a fixed launch site you always need to adjust for some difference of your point of origin versus the orbit you want to achieve.
It helps a bit more than you imply, though: if you can launch from a higher altitude, you have less atmosphere to plow through. That lets you use more of your propellant to speed up instead of to push air out of the way.
You've just got the problem of building a fixed wing aircraft which can carry your rocket full of explosive propellant, successfully release it pointing in the right direction and then get the hell out of the way....
You're extremely limited by the amount of mass you can even launch from a mothership aircraft.
There's no future in this idea outside of small sat, and probably not even there.
There are some companies working on that and / or there have been some experiments with it, but there's two factors there; the one is of course how much weight an aircraft can carry. The other one is the altitude and / or angle; a big plane goes to about 10 kilometers (maybe more, idk), but that's a 'flat' flight, ideally you launch while angled upwards and that's a bit more involved.
But that's how a lot of the X projects were / are done.
That’s what Virgin Galactic was.