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.
I can see the use of this vehicle driving all sorts of design points on the space vehicle, replacing fuel storage space with mission specific equipment.
Probably even can make the structure of the space craft lighter as it doesn't have to withstand the rigors of the launch.
thanks for the...actually explains a lot..will mean they are far cheaper and faster on launches but with a weight limitation i expect.
Awesome. Thank you very much for the helpful info.
Remember the Launch Ramp used in the Movie “When Worlds Collide”?