Need for bigger payloads? Nah, not enough payloads to make it pay.
If the stage is reusable, it could land on Mars if it is refueled in orbit with enough fuel to get there and land. A reusable stage would have a deep throttling Raptor to land back on earth, so it could land on Mars. Again, pre testing ITS equipment on a smaller scale. The Kerolox upper stage doesn't have the ISP for deep space work and fuel is heavier. Raptor is going to be able to deep throttle, Merlin can't.
Yeah. Can we be released from this single thread now that the Raptor on F9 is no longer speculative?
It is a dead end, the USAF was never going to take it to full development
Unless the Air Force wanted a Raptor upper stage to improve F9 for GSO satellites. Or FH. Even if a Raptor upper state is expendable, it would still be cheaper than Delta IV heavy for big birds, and F9 may be able to launch them without FH.
... F9 doesn't seem to need a new US. I am only a layman, but it seems that FH might need a better US. Not adding that for F9 means LC-40 has no need, only SLC-39 would need the mod....Something that I saw asked at least twice, can the current US get stretched to about 2x the current F9 config? FH may need something with more push...
A 5.2m upper stage is the same diameter as the fairing, ...
[Raptor US] ... it just doesn't seem to have any real reason for existence. Test bed for Raptor? Nah. Not needed. Makes the stage reusable? Nah, too expensive to implement and would never make the cash back.
Quote from: SpacenutA 5.2m upper stage is the same diameter as the fairing, ...While going to a 5.2m diameter would be the most aesthetically pleasing way to add more propellant, I suspect that 3.4m would be structurally doable, and much less problematic (i.e. road transportable, factory tooling, etc).
What if Elon leased part of Michoud for 20 years or so? And the associated barges etc. Must be plenty of room in there even with the SLS activities. And if SLS gets canned - Elon might look like a prescient hero; saving jobs and infrastructure etc.Or how feasible would it be to establish factory facilities eventually at Mcgregor, Texas?
But SpaceX does have access to some money to build a smaller ITS. That is a more logical approach. Jim is probably right.