Ablative vs tile heat shields

Since the shuttle, NASA has continued some research and has done some
improvements to the re-usable shields for the shuttle. (carbon/carbon,
traditional tiles, blankets).

Since Apollo, has there been any research on ablative shields ? Have they
been used since then ? (commercial/military launches don't use shields since
they don't return to ground).

If NASA were to build a non re-usable capsule today, would apollo era
technoloogy still be better than shuttle era tiles ?

Has russia improved its ablative shields for soyuz over the years ?

Or are ablative technologies considered mature with not much room/need for
improvements ?

Are there ablative technologies that could be used on a reusable ship where
the ablative coating is re-applied between flights ? Would this be simpler
that shuttle tile maintenance between flights, or would it turn out to be
costlier ?

On Tue, 27 Apr 2004 01:09:00 -0400, John Doe wrote:

Since the shuttle, NASA has continued some research and has done some
improvements to the re-usable shields for the shuttle. (carbon/carbon,
traditional tiles, blankets).

Since Apollo, has there been any research on ablative shields ? Have they
been used since then ? (commercial/military launches don't use shields since
they don't return to ground).

Well, NASA recently used them on a couple of Mars landers...

Dale

Since Apollo, has there been any research on ablative shields ? Have they
been used since then ? (commercial/military launches don't use shields since
they don't return to ground).

Theree was the idea raised here of a reusable capsule with a bolt on disposed
after each launch heat shield.

I woyuld say number one should be reliable, followed by lower cost and lower
weight.
HAVE A GREAT DAY!

From: (bob haller)

Theree was the idea raised here of a reusable capsule with a bolt on disposed
after each launch heat shield.

I woyuld say number one should be reliable, followed by lower cost and lower
weight.

Bob, you forgot PR. PR is always number one.

DF

NASA-Ames has been working for more than 20 years on a reusable ablative
heat shield idea called "Silicone-Impregnated Reusable Ceramic Insulator
(SIRCA)", which is essentially RSI filled with silicone ablator. You can
get more info on what's being going on in the TPS world at the TPS-X website
hosted by NASA-Ames

http://tpsx.arc.nasa.gov/tpsxhome.shtml

I worked on shuttle TPS during the Phase A and B effort (Jan 1969 thru Dec
1971) at McDonnell Douglas. The focus then was on ceramic RSI and composite
carbon-carbon. However, all of the competing shuttle contractors carried
lightweight ablator concepts as backups to RSI and carbon-carbon. IIRC, the
weight penalty with the ablators ranged from 5,000 to about 12,000 pounds,
depending on how the ablator was attached to the orbiter. This was too much
excess weight for NASA, which at that time was struggling to get the dry
weight of the orbiter under 150,000 pounds (without the three SSMEs).
Nevertheless, these ablators were pretty thoroughly tested then, so
engineering feasibility wasn't an issue. What's nice about these ablators is
that the designs called for large curved panels (3 ft x 5 ft or larger)
instead of the tens of thousand of 6" x 6" RSI tiles. Removing these
ablators and reskinning the orbiter with refurbished ablative panels between
each flight would have required several weeks. NASA wouldn't buy into this
because the PR hype at the time was touting the "160 hour turnaround time"
and 60 launches per year for the shuttle (both of which ideas were pure-D
crapola, and we knew it was way back then). Alas, this interesting
technology never flew and has been relegated to history's dustbin.

Later
Ray Schmitt



"John Doe" wrote in message ...
Since the shuttle, NASA has continued some research and has done some
improvements to the re-usable shields for the shuttle. (carbon/carbon,
traditional tiles, blankets).

Since Apollo, has there been any research on ablative shields ? Have they

been used since then ? (commercial/military launches don't use shields
since
they don't return to ground).

If NASA were to build a non re-usable capsule today, would apollo era
technoloogy still be better than shuttle era tiles ?

Has russia improved its ablative shields for soyuz over the years ?

Or are ablative technologies considered mature with not much room/need for
improvements ?

Are there ablative technologies that could be used on a reusable ship
where
the ablative coating is re-applied between flights ? Would this be simpler
that shuttle tile maintenance between flights, or would it turn out to be
costlier ?

I woyuld say number one should be reliable, followed by lower cost and lower
weight.

Bob, you forgot PR. PR is always number one.

DF



Oh thats a automaic! With a lower cost, more reliable system public opinion,
will dramatically improve.

Its bad when the public ponders for many months the last thoughts of the crew
while their vehicle disengrates around them. Espically when it might have been
prevented if management had done a better job.

Things like this dont help nasa public image at all


HAVE A GREAT DAY!

Bruce Palmer wrote:

Would you elaborate on the mindset/mood way back then re. people knowing
the 160 hr. turnaround time and 60 flights per year were fantasy?

I'm not certain the mindset existed. No claim surfaced that 'people
knew then' until a former NASA official stated it during the CAIB
investigation. Other than his somewhat contradictory statements,
there is no evidence to support his claims, and amply evidence to
doubt them.

For instance he (the NASA official) claimed that 'NASA knew the
shuttle would not fly until 1981'. How it was known that there would
be such grave problems with development *before the design was even
completed*, and the reason for selecting the 1981 date, remains
unexplained.

Lastly, the gentlemen to whom you are replying has a massive axe to
grind against NASA.

D.
--
Touch-twice life. Eat. Drink. Laugh.

Well, the mindset way back then was to keep our manned spaceflight program
going after Apollo/Saturn ended in 1972 and to sell the shuttle to the
Congress, the White House and the OMB as the cheap way to do manned
spaceflight. Nixon's OMB was holding NASA's feet to the fire to reduce the
cost of human spaceflight which during the Apollo years was viewed as
horrendously expensive. The Cold War was still roaring along and the Soviets
were launching their Salyut space stations just as Apollo was ending. Ten
years earlier, in 1961, Apollo was born out of fear that Sputnik I and
Gagarin's flight (April 1961) were threatening technological breakthroughs
by the Soviet that had military implications. Now, in 1971, with Apollo
ending, Salyut looked similarly threatening. We needed a new manned
spaceflight capability, and NASA's shuttle was touted as the low-cost way to
go.

So, to satisfy the OMB and the Nixon White House, a mythology was invented
about the cost effectiveness of reusable launch vehicle (RLV) hardware.
According to this rationale, Apollo/Saturn was expensive because that
program used ELVs. The shuttle would have much lower operating cost, $10M
per flight (in FY71 dollars, about $40M per flight in today's bucks) versus
the more than $1B cost for a Saturn V launch because the shuttle is an RLV.
NASA and the shuttle contractors hyped the "airliner-like" operability
expected of the shuttle, relying on the notion that, since the orbiter
looked like an aircraft, had wings and wheels, and landed on a runway
instead of splashing down, most people would buy the notion that the shuttle
should have "airliner-like" operating costs. Each of the competing shuttle
contractors added a major airline corporation to its team as window-dressing
to promote this hype and crapola about shuttle "airliner-likeness". Of
course, all of this hype about RLV cost effectiveness was sheer speculation
since in 1971 nobody had any flight experience with any type of manned
reusable launch vehicle/spacecraft. And there was plenty of previous work
dating back to the mid-1960s that cast doubt on the notion of RLV
cost-effectiveness. NASA and Air Force big-wigs testified before
congressional committees during the Apollo years that reusability was not
likely to reduce the cost of manned spaceflight.

I was a young, dirty-fingernail engineer working my ass off on RSI problems
during the Phase A and B period (Jan 1969 thru Dec 1971). Once we
understood things like the need to completely inspect the TPS (especially
the 7 miles of gap between the tiles) and to re-waterproof at least half of
the 20,000+ RSI tiles between each mission, it was clear that the "160-hour
turnaround" was typical PR hype and proposal crapola that was being used to
sell the shuttle to the Washington decision-makers who hold NASA's purse
strings. The guys and gals working on the orbiter, the SSME and the SRM/SRB
came to the same realization regarding their own particular shuttle system.
When Nixon approved the shuttle development in January 1972, I don't think
anyone seriously believed that the shuttle operating cost could be as low as
$40M per flight. But not even the most severe shuttle critic way back then
would have believeds that it would turn out to be more than $500M per
flight.

Later
Ray Schmitt



"Bruce Palmer" wrote in message
et...
rschmitt23 wrote:

NASA-Ames has been working for more than 20 years on a reusable ablative
heat shield idea called "Silicone-Impregnated Reusable Ceramic Insulator
(SIRCA)", which is essentially RSI filled with silicone ablator. You
can

snip

each flight would have required several weeks. NASA wouldn't buy into
this
because the PR hype at the time was touting the "160 hour turnaround
time"
and 60 launches per year for the shuttle (both of which ideas were
pure-D
crapola, and we knew it was way back then). Alas, this interesting
technology never flew and has been relegated to history's dustbin.

Would you elaborate on the mindset/mood way back then re. people knowing
the 160 hr. turnaround time and 60 flights per year were fantasy? It
sounds like a variation on the cultural issues where NASA workers are
reluctant to speak up about safety issues. Only in this case the bottom
line isn't safety but scheduling reality. Putting safety aside it seems
like there's probably a whole slew of issues people won't speak up on.

Where safety's not a concern you might say that that's somebody else's
job, and indeed, I could see reprecussions if a lower-level worker were
to question something in an area outside of his normal expertise.
Perhaps with justification.

Can a culture where people are encouraged to speak up about safety
issues be cultivated while at the same time not encouraging people to
speak up on other matters? Sometimes it's apparent to even the casual
observer what's really going on, despite management protestations to the
contrary. It seems like a difficult task at best.

--
bp
Proud Member of the Human O-Ring Society Since 2003
(replace ".dot." in email address with ".")

"rschmitt23" writes:
I was a young, dirty-fingernail engineer working my ass off on RSI problems
during the Phase A and B period (Jan 1969 thru Dec 1971). Once we
understood things like the need to completely inspect the TPS (especially
the 7 miles of gap between the tiles) and to re-waterproof at least half of
the 20,000+ RSI tiles between each mission, it was clear that the "160-hour
turnaround" was typical PR hype and proposal crapola that was being used to
sell the shuttle to the Washington decision-makers who hold NASA's purse
strings. The guys and gals working on the orbiter, the SSME and the SRM/SRB
came to the same realization regarding their own particular shuttle system.
When Nixon approved the shuttle development in January 1972, I don't think
anyone seriously believed that the shuttle operating cost could be as low as
$40M per flight. But not even the most severe shuttle critic way back then
would have believeds that it would turn out to be more than $500M per
flight.

So, many areas of shuttle development likely had its suspicions that
shuttle flights would be less frequent and more costly due to between
flight maintenance. Unfortunately, since it was politically incorrect
to raise this issue to upper management, no one at the top tallied the
increased time and cost from all areas to arrive at a realistic
estimate of overall time and cost to turnaround an orbiter between
flights.

This reeks of politics.

Unfortunately, this is the management climate that brought us
Challenger. Beyond the o-ring issue (and other issues that should
have stopped the program until they were resolved), there were many
other issues with keeping the flight rate up, like the lack of
spare parts. I've got some old aerospace magazines from that era that
did report on the spare parts issues, but didn't do much with the
o-rings, brakes, lack of pressure suits and crew escape, and etc.

I guess that's the "can do" culture. Lie to congress and the
administration just to keep the program going and the jobs intact.
This culture is the same one that will surely push for shuttle derived
HLV's to be developed after the shuttle stops flying. This would keep
the launch facilities and many of the large buildings (e.g. VAB)
operating even after the shuttle is long gone.

Jeff
--
Remove "no" and "spam" from email address to reply.
If it says "This is not spam!", it's surely a lie.

jeff findley wrote:
So, many areas of shuttle development likely had its suspicions that
shuttle flights would be less frequent and more costly due to between
flight maintenance.

An unproven assertion. We have the uncorroborated testimony before
the CAIB, and the uncorroborated testimony of an individual with a
known axe to grind vs. NASA. The whole picture is much more complex
than the 'NASA lied knowingly to Congress about the flight rate and
program costs'.

This reeks of politics.

Politics is part of life. Sadly it can and does get out of hand.

Unfortunately, this is the management climate that brought us
Challenger. Beyond the o-ring issue (and other issues that should
have stopped the program until they were resolved), there were many
other issues with keeping the flight rate up, like the lack of
spare parts. I've got some old aerospace magazines from that era that
did report on the spare parts issues, but didn't do much with the
o-rings, brakes, lack of pressure suits and crew escape, and etc.

I'm not certain the spares issue is much more than a red herring. The
Shuttle wasn't originally meant to have an extended service life, and
was viewed as a first generation ship. Given this, and the paucity of
funding, it makes sense that the decision was made to not invest in a
great depth or breadth of spares. (And logistics management is a
complex field that NASA has little to no experience with even now.)
I'm not saying the decision was a correct one, but that it's an
understandable one given the original goals of the program and the
(erroneous) expectation that the money taps would open again. These
consistently forced NASA to choose between saving money on development
(as was mandated by Congress) or saving money on operations (which
required increased spending on development).

OTOH, someone recently pointed out here that Congress got what it paid
for. They consistently funded the Shuttle program below what NASA was
asking for. It's a safe assumption that NASA asked for too much, but
it's an open question where the fault lies between the two. (I've
long noticed that Congress manages quite well to avoid it's share of
the blame in many goverment screw-ups.)

I guess that's the "can do" culture. Lie to congress and the
administration just to keep the program going and the jobs intact.

The common wisdom is that many in NASA's upper management viewed the
'austerity' of the 70's and the Shuttle program in general to be a
temporary aberration. They fully expected that the taps would open
once again, and that the budget would expand to meet their lofty
goals. (Somehow missing the point the one goal that *was* heavily
funded was imposed on NASA, not organic to NASA. NASA's dedication to
that goal was an effect, not a cause) This can be clearly seen in the
continued initiation and submission to Congress of expensive,
long-term, missions (the so-called 'battleships') even as existing
missions and programs were being gutted.

D.
--
Touch-twice life. Eat. Drink. Laugh.