Lindroos is a long time observer and commentator on space
history, RLVs and other space
topics. We exchanged some emails recently and here are some
remarks he made on the OSP:
My "pet concept"
right now would be an air-launched Orbital Space Plane! It appears
to be a workable "third way"; not as difficult or expensive to
develop as a fully reusable spaceplane but still cheaper to operate
since only the big external tank is not reusable. Yes -- people
were saying the same thing about the Space Shuttle. However, this
concept would be 100% focused on rapid-access crew transfer and
resupply. It would not be a huge multimission platform, it would
not require a vast launch pad infrastructure at KSC and the launch
safety and flexibility options would be much better (horizontal
launch vs. SRBs).
The USAF proposed a Boeing 747 based small spaceplane design in
1979 [ http://www.abo.fi/~mlindroo/SpaceLVs/Slides/sld053.htm
] and the Russians have recently revived the concept ("MAKS" --
). In 1993, British Aerospace estimated MAKS would be cheaper
by a factor of ten than Ariane-5/Hermes. This means the cost per
seat would fall from ~$30 million for the Delta IV OSP to about
$3 million. I think we would see more Dennis Titos and Mark Shuttleworths,
and it would be easier to move commercial experiments to ISS as
< groan... > Winged vehicles and ELVs just don't mix very well.
DynaSoar, Hermes and the rest all encountered problems with weight
growth, crew safety and LV/mini-shuttle aerodynamic integration.
A winged vehicle will invariably be heavier than a capsule, and
the wing area must be kept to a minimum or else bending loads
on the booster will become a major problem. The end result is
that many key subsystems will have to be moved to an expendable
"orbital module" which is jettisoned before reentry so that the
vehicle is light enough to glide back to a landing airfield. The
weight problem will only get worse when NASA tries to come up
with a realistic crew escape system...
ELVs are dangerous
and unreliable during ascent to orbit. The only good solution
(an escape tower+separate crew capsule) won't work for weight
reasons, and ejection seats will not be good enough. Standard
fighter aircraft seats only work below Mach 2 or so and they will
not move the crew sufficiently far away fr! om an exploding rocket.
More powerful high-altitude seats will kill the astronaut unless
the seat is encapsulated, XB70 Valkyrie-style. The Hermes engineers
tried all kinds of approaches before settling for ejection seats;
this limited the number of crewmembers to three per flight for
weight and volume reasons. And they were going to pay 130 million
Euro for that.
If NASA *must*
have an EELV-launched crew transfer vehicle, it should develop
a capsule instead... ESA estimated that an 8-man CTV capsule could
be developed for about $2 billion vs. $5.5B+ for Hermes. Unfortunately,
Europe had already wasted $2 billion on Hermes by this time!
Ketchledge, who has extensively studied re-entry systems
and lifting body designs, discussees thermal protection issues and
responds to my entry "Ten
Years and $35 Billion? :
I am Dave
Ketchledge a senior member of both Tripoli an the NAR who worked
in guided model rocketry and other major topics in the 1990s's
In 1988 I released to CompuServe my 600 page work called "Microshuttle"
for a lear jet sized space plane. North American Rockwell, Boeing
and the Navy were favorably impressed with the effort. In 1997
I was a keynote speaker to University of Illinois school of Aerospace
Engineering on the topic of rocketry education and Flight Mechanics.
Currently I am working on aerodynamics analysis on lifting bodies
like the X-33, X-38 for an upcoming publication planned well before
this tragic event.
In my Microshuttle work I spent a chapter on the subject of aerothermodynamics
stating that the Ceramic tile system on the Shuttle was
poorly bonded to the vehicle and was time consuming to keep in
operation. My suggestion which I own a copyright on is a foaminated
boron silicate glass with a pyrolized graphite skin panel. While
heavier than a shuttle tile, the graphite/glass matrix offered
outstanding ability in mechanical and thermal conditions. Current
NASA R&D with metal heat shielding such as ARMOR would be essential
on a next generation orbital space plane.
The issues in reentry are vehicle surface area, wing loading (weight/area
) and air density. The shuttle with a high wing loading flies
a profile lower in the atmosphere with a higher BTU transfer rate
over time. Lifting body vehicles with higher surface areas offer
lower heating rates and support metal thermal protection except
for leading edges where carbon-carbon-silica carbide is required.
Subsonic L/D values from 4-7 are possible with the right design.
The X-20 Dyna Soar or Hope-X programs offer good airframes for
consideration in the OSP programs. The X-43 with its stubby wings
does not support the metal reentry tile concept due to a low surface
area. Its manufacturer needs to go back to the drafting board
and rethink its OSP submittals with aerothermodynamics in mind.
The nation needs to consider retiring the shuttles and use the
Delta IV for now to launch the OSP and can do so in 5 years if
the funding is there. Using the K-1 would also be an idea. And
other vendors such as AST offer outstanding concepts well worth
NASA should look at its prior research efforts and have a focus
group with the Air Force and ISS partners to hammed a design out.
With the right design, we will arrive with an ISS rescue craft,
a manned transport vehicle and can use the remaining shuttle parts
for cargo lifting even for a real Mars program at a fraction of
a cost. But government has to think out of the box and embrace
rapid design and development found in industry to gain success
while remaining safety focused.
I know that well, since I have over 20 years in nuclear instrumentation
engineering in my professional background. America has suffered
a major loss indeed, lets make he right choices and get a better
shuttle at a lower operational cost with a metal reentry tile
system and crew escape provisions like the capsule had. IT does
not take 35 billion and a decade. It takes maybe 2-4 billion in
5 years to get a flying and orbital prototype. And the military
would have a strong interest without a question as well.