Mojave airport is not a spaceport

In article ,
Andrew Nowicki wrote:
the absolute temperature by about 40%, from ~1690 K to
about 1000 K.

That is still not bad! Melting point temperature of
aluminum is 930K.

However, maximum *service* temperature -- the temperature at which
aluminum alloys retain useful amounts of strength -- is rather lower.

If the rocket is pump-fed, its long, flimsy tank will melt away.

If the designer has goofed and neglected to protect it, that is. (By the
way, you're assuming that said tank is aluminum, which it might not be.)
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

Henry Spencer wrote:
If I am wrong, NASA, Boeing, Lockheed Martin, and the
likes will flock to the Mojave airport.

Why should they? Their launch systems all use vertical takeoff, and thus
cannot legally operate from Mojave.

I suspect that the FAA could be convinced to allow moderate sized VT and
VL operations from Mojave spaceport, though the paperwork so far does
not allow for it.

The killer problem is that Mojave *port is not isolated enough
for *large* rocket operations, Horizontal takeoff or not.
There's a town with several thousand people right up against the
side of the *port. There's a freeway nearby. The *port itself
is full of people and expensive stuff well within the danger
zone if, for example, a large rocket fell over and exploded
(which is a risk with any launch mode, and reusable or expendables).
With oxidizer on board there is larger risk than just large
fueled aircraft.

I think that Armadillo Aerospace's vehicle would probably still
be within reasonable safety margins; with people on board,
the risk of it coming down in town is not a lot more than
that of a large jetliner sized experimental aircraft,
and the damage potential probably comparable. Someone would
have to work out the various impact damage assessments
in detail though.

Launching any serious orbital mission would probably
be right out, though. An air-launched vehicle which
was transported by aircraft further away from the
city of Mojave isn't all that much of a risk,
because the odds of a takeoff accident are so
remote with a jetliner, but a ground launch of
any rocket, even fully reusable ssto manned with
wings and all, is much riskier for the forseeable
future.


-george william herbert

Andrew Nowicki wrote:
AN That is still not bad! Melting point temperature
AN of aluminum is 930K.

Henry Spencer wrote:
HS However, maximum *service* temperature -- the
HS temperature at which aluminum alloys retain useful
HS amounts of strength -- is rather lower.

True.

AN If the rocket is pump-fed, its long, flimsy
AN tank will melt away.

HS If the designer has goofed and neglected to
HS protect it, that is.

Is there a lightweight insulation that can do
the job? Maybe 3M's Nextel?

HS (By the way, you're assuming that said tank is
HS aluminum, which it might not be.)

There are 4 options:
- Aluminum alloys are cheap and have high
thermal conductivity which is useful in engines
and heat sinks. If this is going to be integral
engine/tank pressure-fed design, it would be
nice to use the same material for the engine
and the tank to avoid thermal expansion problems.
- Titanium alloys has high melting point temperature,
but low thermal conductivity -- not good for the
engine.
- Composite tanks have impressive specific strength
(strength-to-weight ratio), but they are hard
to integrate with metal parts because of their
different coefficient of thermal expansion.
- Steel is inferior to the other materials.

AN Russian Baikal is a winged, reusable first stage which
AN is going to be a part of a two stage launcher...
AN Russia is almost a landlocked country, so they have no
AN choice but to make the winged first stage.

HS Sure they have. They were planning to recover the
HS Energia first stage (the strap-ons) with parachutes.

Yes. I have seen a russian drawing of a rocket hanging
on a parachute and being picked up by a helicopter.
I guess they favor the winged Baikal now.

HS For that matter, Kistler planned to launch from Nevada,
HS and recover its first stage -- at the launch site,
HS after a post-staging turnaround burn -- with parachutes
HS and airbags.

Gas bags were used on Mars, but the Soyuz capsules have
small rockets instead of the airbags. The rockets
malfunctioned a few times, but they were not replaced
by the gas bags. The gas bags may be feasible for a
stubby rocket, but a slender one would need lots of
them. If you launch a two stage rocket from Mojave,
its first stage will land in a rather populated area,
so it will need a landing site and a special parachute
which guides it to the landing site. Cross-range of
such a parachute is not impressive, so the first stage
must be guided before the parachute opens.

All these complications add up to the cost.

AN A pressure-fed splashdown rocket is much simpler
AN and cheaper than the Baikal.

HS Simpler and cheaper to build, yes. But as for
HS simpler and cheaper to operate... the verdict has
HS to be "not proven".

'Not proven' is a reasonable argument against a novel
contraption which is either very complex, or fails
catastrophically, or has to work in a very hostile
environment. Long time ago (1968) Arthur Schnitt ran
very successful static tests of pressure-fed 'dumb
boosters.' Pressure-fed rockets made of aluminum
alloy have dry/wet mass ratio of about 0.1. Pump-fed
rockets have the ratio of about 0.06, but they are
not completely dry when they stop running. My favorite
design, the engine cluster, has high expansion ratio,
so its specific impulse is also high: 330 seconds --
not bad for oxygen/methane. Maybe you are just too
sophisticated to appreciate the simple beauty of the
AK-47 rifle and the pressure-fed rockets :-)

Andrew Nowicki :

Earl Colby Pottinger wrote:

You have a strange idea about how pressure-feeded
rockets must operate/land. Please tell why the
following pressure feeded rocket would need an
ocean to land in?

There is a big diference between a sounding rocket
and a rocket launcher. The rocket launcher with
fixed wings (like the Space Shuttle) is a bad idea
because the wings produce too much atmospheric drag
during launch and they heat up during reentry.
Russian Baikal has foldable wings.

This is a matter of economics. All this extra
airplane gear adds weight, cost, and complexity.

That was not a sounding rocket. Please read the site.

Earl Colby Pottinger

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Andrew Nowicki wrote:
Andrew Nowicki wrote:
AN Does it mean that the spent first stage is
AN dropped near Phoenix, Arizona...

Henry Spencer wrote:
HS No, its pilot turns it around and flies it back
HS to base. Or, possibly, glides it down to a landing
HS at some suitable airstrip, from which it is trucked
HS or flown back to Mojave, although that's rather less
HS convenient.

HS What part of "horizontal-takeoff-horizontal-landing
HS only" is so hard for you to grasp?

Russian Baikal is a winged, reusable first stage which
is going to be a part of a two stage launcher. Russia
is almost a landlocked country, so they have no choice
but to make the winged first stage. (They would like

Oh? Well, guess what, the country from which Soyus presently
launches is entirely land-locked and it does not have wings on
any stage.

to make a spaceport in French Guiana.) A pressure-fed
splashdown rocket is much simpler and cheaper than the
Baikal. This is why a spaceport on the Atlantic coast
makes sense, but the spaceport in the landlocked Mojave
airport does not make sense.

There is no Russian launcher by the name "Baikal" AFAIK.
Maybe you are thinking of Buran?


If I am wrong, NASA, Boeing, Lockheed Martin, and the
likes will flock to the Mojave airport.

You are wrong in too many ways for your righness or
wrongness to matter.


HS Your pressure-fed artillery rockets will *never*
HS operate out of Mojave, and it's got nothing to do
HS with where the pieces falling off would land.

The pressure-fed rockets can have foldable wings, jet
engines, landing gear, etc., but all this extra hardware
is far more expensive and less reliable than the rockets.

well yes, and given sufficent thrust even pigs fly. so what?

--
Sander

+++ Out of cheese error +++

Andrew Nowicki writes:

Andrew Nowicki wrote:

AN There is no ocean to the east of Mojave,
AN so you cannot make cheap pressure-fed rockets,
AN splash them down and reuse them.

Henry Spencer wrote:

HS You couldn't do that from Mojave Spaceport anyway,
HS because (last I heard) their spaceport license is
HS for horizontal-takeoff-horizontal-landing launch
HS vehicles only. They've decided to cater to one
HS particular type of vehicle, rather than covering
HS the whole spectrum... you launch eastward...

Single stage rocket launchers do not exist. Does it
mean that the spent first stage is dropped near
Phoenix, Arizona, and the spent second stage is
dropped on Texas?


You know, I just watched a space launch from the Mojave
spaceport just under two hours ago. The pilot of the
first stage did a perfectly serviceable job of not hitting
Phoenix by the obvious method of turning around and flying
back for a landing at Mojave.


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In article ,
Sander Vesik wrote:
There is no Russian launcher by the name "Baikal" AFAIK.
Maybe you are thinking of Buran?

No, Baikal is a proposal for (if I haven't mixed it up with another paper
rocket) a winged flyback version of the Angara first stage.

Angara is a real project, although chronically short of funding. Baikal
is just pretty pictures at present.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

Henry Spencer wrote:
In article ,
Sander Vesik wrote:
There is no Russian launcher by the name "Baikal" AFAIK.
Maybe you are thinking of Buran?

No, Baikal is a proposal for (if I haven't mixed it up with another paper
rocket) a winged flyback version of the Angara first stage.

Angara is a real project, although chronically short of funding. Baikal
is just pretty pictures at present.

I see. Too many different russian projects starting in 'b'

--
Sander

+++ Out of cheese error +++

Andrew Nowicki ) wrote:
: The Mojave Airport is a perfect place to test
: airplanes and sounding rockets, but it is probably
: the worst place on Earth to locate the space rocket
: launch site -- Manhattan would be better. There is
: no ocean to the east of Mojave, so you cannot make
: cheap pressure-fed rockets, splash them down and
: reuse them. A big city (Los Angeles) is just 100 km
: south of Mojave. The nearest pacific coast is 130 km
: south west, next to Ventura, California. If you
: launch the real thing, you will have to launch it
: in the south west direction and hope it will not
: fall on Los Angeles.

: NASA should make the Kennedy Space Center available
: to independent rocket makers.

Wallops Island in Virginia?

Eric

Eric Chomko wrote:

Wallops Island in Virginia?

It seems that Wallops is the best:
http://www.wff.nasa.gov/pages/fabrication.html

....but there are other launch sites:
http://www.hobbyspace.com/SpacePorts/spaceports3.html