Paul Allen gets into the space launch business

[orogenicman]

Seems like a risky venture, but could be revolutionary if it works, and they address all the safety and technical issues.

[Cinjin]

I heard this idea many years ago, even back when the Shuttle missions were booming.

Which I guess leads me to one conclusion: There's something inherently difficult and/or dangerous about this concept for them to not have tried it by now. "Them" of course being Nasa or some other private corporation bucking for a shot at the title.


Thoughts?

[orogenicman]

Our B-52s have been used as platforms for launching everything from cruise missiles to small research satellites for decades. The difference here is one of scale. Probably the cost of building and maintaining such a large vehicle is high, but compared to the cost of a ground launch, probably not so much. Launching from high altitude can save on expensive rocket fuel and reduce the launch weight, which can allow for heavier payloads, or higher Earth orbit at a significant savings.

[Anomalocaris]

Small rockets spend a larger proportion of their fuel to overcome air resistance in low altitude, due to the fact that drag scales with square of dimension while fuel and mass scale with cube of dimension. So it is more advantageous to use an airplane to help a small rocket, like pegasas launched from b-52 mentioned above, to overcome parts of lower atmosphere resistance that to help a larger one. Any rocket that can puta six men capsule into orbit is very large indeed, on the scale of a delta or atlas rocket at very least. These don't burn much of their fuel overcoming lower atmosphere resistance, so is not helped per se tremendously by being launched from air.

Then the air launcher turns into simply a reusable first stage. But a subsonic air breathing launcher is a very weak first stage, giving a very modest amount of energy to the rocket compare to a proper rocket first stage. So it doesn't save the rocket a great deal to be launched from 50,000 feet but Mach 0.7, then ground level standing still. Your typical first stage ground launched rocket would have be traveling at Mach 3 and have gained maybe 5-6 times more energy by this altitude, and would have expended only something like 1/2 of its fuel. So this air launcher would save the first stage maybe 10 percent.

The economics of air subsonic launch of large rocket is thus it doesn't save a great deal of fuel weight for the rocket, but does add the cost of large, unique, possibly one off airplane, in addition to adding cost and weight by requiring the fully laden rocket to withstand unusual ( for a lunch rocket) stress of bing slung horizontally while fully fueled.

[houseofcantor]

Ever see Wile E Coyote? Yes, there is something inherently dangerous about strapping a bomb to your ass and lighting the fuse; unfortunately most propulsion systems use these types of opposing vectors. When it comes to space, I am in the "let's do it" camp - as soon as someone brings up "safety" my programming goes - it is not safe to keep humanity on one blue marble.

I'm not up for recklessness, I'm up for shit moving forward.

[popeyespappy]

This was pretty big news around here. Both Stratolaunch Systems and their systems integrator Dynetics are local companies. It didn’t come as big surprise though. Stratolaunch signed a 20 year lease for their headquarters at Cummings Research Park earlier this spring and there were rumors then.

One of the advantages that a liquid fueled ground launched system has over this plan is that it can be shut down if there are problems before the vehicle leaves the ground. I watched that happen a couple of times with the shuttle from a console at the HOSC back in the 90’s. With an air launch system like this one you let it go then hope it fires and everything works right. If not you better be somewhere over the ocean.