July 2003 update: Kestrel upper stage versus Delta II
- From:
- Elon Musk
- Date:
- July 2003 ('Update for July' 2003; HobbySpace noted on 29 August 2003 that it had been posted on spacex.com.)
- To:
- SpaceX update mailing list
Excerpt. Only this much of the email has been made public.
Delta II rocket upper stage has a specific impulse of 319s and a mass efficiency of 86%, compared to the expected Falcon specific impulse of 325s and mass efficiency of 91%. Our inert mass being one third better than Boeing's is very significant as that translates to a pound for pound improvement in actual payload to orbit
[...]
biggest single advantage we have is our use of advanced aluminum-lithium for the propellant tanks rather than steel in the Boeing case. We also employ a blended system of both heated helium and gaseous oxygen to pressurize the tanks, significantly reducing our pressurant weight.