HUGE difference in mass of propellant required between cooling rocket
engines exposed to reentry by trickling propellants through them, and
avoiding reentry heating by burning propellant to decelerate prior to
reentry.
Also between propulsive deceleration prior to reentry, and "powered
descent plus landing". All realistic approaches to the latter involve
aerodynamic braking down to the vehicle's subsonic terminal velocity,
then only using rocket thrust to handle the last couple hundred meters
per second of deceleration.
You seem to be conflating and confusing three very different things,
incorrectly.
As for why certain parties dismissed powered vertical landing as
impractical decades after DC-X proved it (and well after a variety of
Lunar Lander Challenge entries repeated the proof) until SpaceX finally
made that position utterly untenable, you'd have to ask them.
Henry V
On 2/12/2018 7:48 AM, John Dom wrote:
I seem to remember a discussion on AR years ago about recovering rocket
stages whereby the engines would serve as heatshields by circulating liquids
through their cooling channels during descent. But never by powered descent
plus landing, an option Falcons demonstrated to work.
All comments at that time on powered reentry were
poppycock/negative/laughing stock entries ... why such common
shortsightedness then?
I do not think the powered and chute less VTVL reentry option was invented
by Musk & team. Then who invented it? NASA people? Was there a patent about
the issue on which SpaceX based further development into the Falcons
reality?
Rupert Sheldrake's theory applicable?
John
-----Original Message-----
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of Henry Spencer
Sent: maandag 12 februari 2018 3:13
To: Arocket List
Subject: [AR] Re: SSTO
On Sat, 10 Feb 2018, John Dom wrote:
... Who knows where the Skylons would be by now if they got the same
help SpaceX got...
Probably not much farther than they are now, given that the help to SpaceX
was hundreds of millions to produce flying rockets with flying capsules on
top, while Skylon development is still forecast to cost tens of billions and
there is no plan for a less-expensive demonstrator first. (Which puts
Skylon in the "need not be taken seriously" category, in my opinion, since
nobody is going to spend that kind of money on an unproven concept.)
Henry