those that throw the rocket off the aft end of an aircraft and fire it vertically loose a lot, probably half, of the DV advantages of air launch
Well, we could reuse them... problem is, NASA calculated in 1970 that a reusable (multistage, not SSTO!) launch vehicle becomes cheaper than an expendable around 50-60 flights a year... no problem! Shuttle will fly *100* times a year!!! (cough, cough...) Around 2000, NASA paid six companies (Orbital amongst them) several millions of $$$ to research "Seconf Generations RLV's" and they found out that RLV's become cheaper than ELV's at the rate of... are you ready?... 50-60 flights/year! Why? Isp amd mass fraction are the same today as they were in 1970.
antonioe - 19/8/2006 4:21 PM“Any idea why t/Space intends to drop their rocket from an aircraft so it lights vertically even if it reduces the DV advantage of air-launch?”Near-vertical launch loses the forward velocity and gravity losses of wing-assisted horizontal drop, but retains almost all of the pressure advantages of the altitude start. In particular, it would allow me to use a pressure-fed first stage, whereas a pressure-fed first stage at sea level would be the kiss of death.
Also, I could use relatively unmodified military cargo aircraft using a rear-ramp extraction method; if I had to launch 6 air-dropped rockets within 10 minutes, 6 C-17's would do the trick.
There is also the issue of the Orbital Pegasus patent, which covers the wing, although I’m sure Orbital would be glad to license it at a very reasonable rate to anyone foolish enough to think there’s a market there for another Pegasus-class vehicle… we barely make a living out of it…
I would like to say that I'm impressed with what Orbital has accomplished. They were the first people to make commercial space work.
“Surely the Pegasus wing patent has expired by now?”
“how much flight rate affects ELV pricing?”
“Would we come out ahead if we doubled/tripled the EELV flight rate by moving all Delta II size payloads onto it and ditching Delta II entirely?”
”laws preventing the use of surplus ICBM hardware for space launch are wise?”
“With 50 Peacekeepers left over, it seems like the payload side of the low-cost space problem could get a big boost from those being made available”
Actually, not much of the forward velocity is lost. Keep in mind that the AirLaunch LLC (not t/Space) system does not use the parachutes and pallet the way SRALT/LRALT do. Ignition takes place when the rocket has pitched up to nearly vertical, but there is still significant forward velocity. Of course, the low thrust to weight of a liquid results in the vehicle continuing to fall for several seconds and the 90 deg AOA is not a normal launch vehicle design case.