[AR] Re: SpaceX Single Stage to Orbit
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Wed, 22 May 2019 15:54:05 -0400 (EDT)
On Wed, 22 May 2019, Craig Fink wrote:
Landing Propellant mass fraction used for delta-V should be significantly
less for this prototype than for the Falcon 9 first stage.
Which is basically irrelevant, since they're different classes of vehicle
and the pre-descent demands on this one are rather greater than those on a
Falcon 9 first stage.
...Like an aircraft flying across Pacific, one would not expect the
aircraft to carry enough fuel for the return trip. For a Launch Vehicle,
the Destination is LEO, a place to let passengers and cargo off, take on
new passenger and cargo and Refuel for the return trip.
Remember that a sensible RLV, especially one that carries passengers,
needs the ability to *abort* a flight without losing vehicle or payload.
Reaching a LEO station can't be an essential preliminary to making a safe
descent, because you might not be able to get that far. Airliners *are*
expected, indeed required, to carry enough fuel to execute their abort
procedures when needed.
Henry
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