Re: Shuttle Flights Halted

On Dec 22, 1:18 pm, behlin...@xxxxxxxxx wrote:
On Dec 22, 12:21 pm, Len <l...@xxxxxxxxxxxxxx> wrote:

1.  A space transport system should be far more
robust than current launch systems.  A big step
in this direction is to design the operations and
system to avoid hand-wringing crucial situations
--such as engine-out abort on takeoff.  IMO,
this is a basic, step-1 requirement that had
generally been ignored in all launch systems
built to date.

2,  With GPS and other on-board capabilities, I
view controllers on the ground as an extra--
probably valuable--additional capability, but
not a necessity.

3.  Horizontal takeoff is not

only an advantage for engine-out abort, but
it also makes range safety somewhat less
critical, because the space transport can be
clear of the beach and out to sea somewhat
before gaining a lot of altitude high over the
launch complex.  It seems to me that a lot
or problems can be avoided by getting away
from our current launch-vehicle mindset.

Len

1.  you got the money for a more 'robust" system.  Nor does anyone
else

Maybe. Time will tell.

2.  Launch vehicles are not "controlled" from the ground.  Once they
launch, they are autonomous, except for range safety.   The launch
control centers have no real role after T-0 other than monitoring
telemetry.  They have no capability to alter anything on a launch
vehicle. This applies to all US launch vehicles.  Same goes for the
shuttle, mission control just advises the crew

I'm not against advice from the ground. I
just like to avoid having the tail wag the dog.
When we start flying thousands of flights per
year, an FAA space traffic control and advisory
service will probably be well justified. This might
end up being a combined FAA/NASA Houston
operation.

3.  Horizontal takeoff require aerosurfaces which are useless in the
latter part of flight and actually reduce performance

A system designer should design to the total
job and the total trajectory. The aero surfaces
of the carrier stage are useful during the whole
initial boost, staging and recovery phases. The
carrier and its 1000 m^2 wing (without the orbiter)
can actually pull 2g's at the mach 2 / 40 km staging
point where dynamic pressure is only 750 Pa.

The orbiter, conversely is relatively unaffected by
the relatively thin air.

If it is necessary to abort before staging, the
carrier can recover with the orbiter, if orbiter
propellants are jettisoned. If abort is necessary
just after staging, then the orbiter (after jettisoning
propellants, if appropriate) can glide back to the
launch-site runway for an unpowered landing.
The carrier always makes an unpowered landing,
with or without the empty orbiter on board.

Since the carrier is like a huge ultralight on
landing, we will probably have special runway
vehicles grab each wing tip if conditions are
somewhat gusty. Landing speed is unusually low.

The aero surfaces of the orbiter (in our "kite-plane"
approach) are unusually light and perform the
reentry phase and landing phase in a manner
that quite justifies the mass of the orbiter
aero surfaces. My calculations indicate that
a proper allowance for landing with vertical
thrust would require a greater mass than the
orbiter aero surfaces. Our TPS is practical,
based upon low planform loading and relatively
low reentry temperatures; overall TPS mass is
quite reasonable in spite of the 250 m^2
lower surface of the orbiter wing. All transparent
areas are in the lee. The orbiter upper surfaces
do not require TPS. The orbiter is aerodynamically
stable though-out reentry.

Len
.

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