I’ve had the same thoughts myself.
All I care about is that I get the economically valuable parts back in useful
condition. It doesn’t matter if they return singly or all at once. The physics
behind it seem to give an enormous advantage to staged boost (and thus staged
return)
On Feb 11, 2018, at 4:04 PM, Eivind Liland
<spookysys@xxxxxxxxx<mailto:spookysys@xxxxxxxxx>> wrote:
What’s the appeal of an SSTO over landing your multiple stages of boosters? I’d
think you’d get less payload to orbit for the same fuel, so if you already
solved re-use of the first stage.. what is it?
11. feb. 2018 kl. 21:13 skrev Craig Fink
<webegood@xxxxxxxxx<mailto:webegood@xxxxxxxxx>>:
On Sat, Feb 10, 2018 at 2:46 PM, William Claybaugh
<wclaybaugh2@xxxxxxxxx<mailto:wclaybaugh2@xxxxxxxxx>> wrote:
Today, I would want to carefully understand two technologies: very low power
thrusting during entry to provide a stand-off gas blanket (and specially the
mass of propellant required)
I too have been thinking about this one for a while, and seems to me to be the
way to go. If done right, I would think the mass penalty would be minimal. But
first, the vacuum engine bell has an expansion ratio that is too large to
operate deep in the atmosphere, but it will run just fine without it's nozzle
extension.
One solution fits
https://i.stack.imgur.com/uKx53.jpg
So, the extension needs to be replaced with a variable nozzle extension similar
to a jet, but designed for a rocket and able to open much wider (even
reversing) for the heat shield mode. The weight of the much heavier variable
nozzle extension could be mitigated by removing the engine gimbals and
traditional TVC and using the variable nozzle extension for ascent, entry and
atmospheric flight TVC. Increasing the expansion ratio of the variable nozzle
increase ascent performance, while providing additional "wake shielding" of the
tanks. The second stage could then land on the engine to nozzle extension
joint, so landing gear would not be required.
The "stand-off gas blanket" or film cooling of the variable nozzle extension
would be minimal for parts that are all ready built from high temperature
materials. I would think this type of entry would favor a short high gee entry
of a longer lifting low gee entry. The CG of the second stage is at or near the
engine resulting in a dynamically stable entry and atmospheric flight. Plus,
assent, entry and landing forces are all in the same direction, the structure
was built to handle load in the +X direction.
--
Craig Fink
WeBeGood@xxxxxxxxx<mailto:WeBeGood@xxxxxxxxx>
