But, as Bill also said, the primary benefit of air launch is insertion flexibility and single-orbit rendezvous. This is currently driven by military requirements, but in the future, it could be attractive for space passengers who want to minimize the time to reach an orbital facility.
On 2015-02-16 12:37, Lloyd Droppers wrote:
Liam, It is not a textbook, but a good place to start for air launch information is the Pegasus User's guide [1]. It is the only air launch orbital launch vehicle I know abut that has been successful and the User's guide and a fair of general information on the air launch concept. I also agree with Bill here in that air launch is a probably going to be more expensive than ground launch, and that the vehicle, or at least the first rocket stage, really wants to be a solid. Lloyd On Mon, Feb 16, 2015 at 2:18 AM, Bill Claybaugh <wclaybaugh2@xxxxxxxxxx> wrote:Liam: I do not know of any reference but here are some general observations: - in general, air launch is more expensive than ground launch (I know Burt says the opposite, but he is provably wrong). - if custom built; air launch drop aircraft are typically more costly than a ground launch pad for the same size solid rocket. - annual O&M costs to maintain flight certification are typically higher than the same costs for a solid rocket ground launch pad. - horizontal drop requires a pull-up maneuver; the lowest mass way to do that is wings, but all that mass is unneeded for ground launch. The alternative is to have the drop aircraft pitch up; that requires a much higher performance aircraft. - air launch rockets want to be solids, particularly if horizontally launched. Feed system complexity and slosh issues during the pull-up add still more mass to a liquid solution which is not offset by the increased Isp. - most of the additional performance from air launch is in the higher area ratio of the first stage motor; the velocity imparted by the aircraft is trivial in comparison. - to make air launch economically competitive the aircraft has to have some other user (e.g. sub-orbital joyrides; carrying large or bulky cargo); otherwise the O&M cost quickly drives the project to the high cost, low flight rate corner of the box (Pegasus, for example). - the advantages of "any orbit; any time" are largely national security related; in the absence of such a sponsor / customer there is very little commercial justification for the higher cost of air launch. Cheaper to wait for the desired orbit to pass over the launch pad. (Which, BTW, argues for a single, all azimuth, ground launch pad.) Bill Sent from my iPhone On Feb 14, 2015, at 12:38 AM, Liam McQuellin <lmcquellin@xxxxxxxxxxx> wrote:Hi All, I am writing a paper and I am looking for a text book thatdescribes air launch concepts. Does anyone know of any they could recommend?Thanks, Liam McQuellin Australian Space Research InstituteLinks: ------ [1] http://cms.orbitalatk.com/SiteCollectionDocuments/Orbital%20Data%20Sheets/Pegasus_UsersGuide.pdf