Title text:
It does come at the cost of some launchpad expansions and increased fuel requirements, but that all comes out of the facility’s budget.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3291/
air launch is dumb. it provides almost no benefit from a deltaV perspective while dramatically increasing the engineering cost and complexity of the launch system. just because people are working on it doesnt mean its going to be useful or practical or even work. even if it does eventually work for someone someday it wont be worth the effort or cost. theyll cancel it after a few launches or go out of business because no one can afford their overpriced copium machine.
Wouldn’t the main benefit to air launch be the elevation gain? Flight through wings is way more efficient than just raw thrust
I think the main advantage of air launch is there is less air in the way.
If you didn’t have any air resistance you could go faster earlier and reach orbit faster. This means less fuel wasted on fighting gravity, but because we have an atmosphere, there is a speed limit.
the elevation gain is a marginal benefit compared to the velocity required. no plane is going to give a meaningful velocity as a first stage, and at best will give not nearly enough altitude to matter, while severely limiting the maximum mass of the rocket.
just for some context, the energy to lift 1kg to an altitude of 500 km is 4.9 MJ (being extremely generous and assuming constant surface gravity), while the energy to accelerate 1kg to a velocity of ~7.6 km/s (the required velocity for a circular 500km orbit above the earth) is 28.9 MJ. so even if the plane could magically get the rocket all the way to altitude, it only saves about 14.5% of the energy required to achieve orbit.
practically speaking its likely impossible for a plane to get past the karman line (100 km) without the assistance of a rocket engine, and according to wikipedia the altitude record for a jet plane is only 37.6 km, which is only 7.5% of a 500 km orbit. its just way easier and cheaper to make a bigger rocket than to bother with putting a rocket on a plane.
I mostly agree. It’s not an efficient way to get to orbit.
It was an early attempt at reusable launch vehicles, it was a good idea, that turned out to be overcomplicated. The Pegasus 100% worked though, it went to orbit, so it’s not a question of “could it work someday”, it did work, it was just more expensive than the standard methods.
Again, I’m not saying this is an avenue worth exploring, I’m just saying that it’s incorrect to call it impossible.