"Heavy lift: examining the requirements"

"Rand Simberg" wrote in message
.. .
No, thrust termination means shutting down the engine without
destroying it. Words mean things.

It's interesting that googling on "thrust termination systems" produces lots
of information directly identifying solid motor thrust termination systems
as part of flight termination systems and the process of SRM destruction by
range safety. For example, John Carmack (at
http://science.slashdot.org/article....id=160&tid=112)
said, "We wanted to use parachtues as a quick hack for the X-Prize, but the
test range where we were planning to fly was going to require a half million
dollars of "engineering support" and wanted us to carry a thrust termination
system (bomb) on the vehicle to satisfy themselves that it won't drift out
of the range." Notice "bomb" in parentheses (his usage, not mine).

I think we have here another case of Rand attempting to push *his*
definition of a system on the rest of the world. Thrust termination which
does not destroy the vehicle will no doubt have a place in future reusable
launchers, but to insist that this is the only definition in the face of
industry usage is not reasonable.

-Kim-

On Sat, 12 Mar 2005 21:08:43 GMT, in a place far, far away, "Kim
Keller" made the phosphor on my monitor glow in
such a way as to indicate that:


"Rand Simberg" wrote in message
. ..
No, thrust termination means shutting down the engine without
destroying it. Words mean things.

It's interesting that googling on "thrust termination systems" produces lots
of information directly identifying solid motor thrust termination systems
as part of flight termination systems and the process of SRM destruction by
range safety. For example, John Carmack (at
http://science.slashdot.org/article....id=160&tid=112)
said, "We wanted to use parachtues as a quick hack for the X-Prize, but the
test range where we were planning to fly was going to require a half million
dollars of "engineering support" and wanted us to carry a thrust termination
system (bomb) on the vehicle to satisfy themselves that it won't drift out
of the range." Notice "bomb" in parentheses (his usage, not mine).

I think we have here another case of Rand attempting to push *his*
definition of a system on the rest of the world.

I didn't know it was *my* definition. It's the definition of everyone
I know (e.g., at Boeing, on the OSP program) who talks about what is
necessary to human rate a launch vehicle. Any other definition leads
to great confusion.

Jon S. Berndt wrote:

I used to do this when building Estes model rockets! [BTW, I lost two
Saturn V's to rocket motor failures - Estes replaced them both]


Wish I'd known they would do that when I semi-flew my Saturn IB... it
used 4 C6-5 engines, but I was never able to get all 4 to light at once.

Fun model to build, though...

--
Reed Snellenberger
GPG KeyID: 5A978843
rsnellenberger-at-houston.rr.com

"Rand Simberg" wrote in message
.. .
I didn't know it was *my* definition. It's the definition of everyone
I know (e.g., at Boeing, on the OSP program) who talks about what is
necessary to human rate a launch vehicle. Any other definition leads
to great confusion.

Then you might want to take this up with the launch industry.

-Kim-

"Kim Keller" wrote in message news:vTIYd.170971

"Rand Simberg" wrote in message

No, thrust termination means shutting down the engine without
destroying it. Words mean things.

For example, John Carmack (at

http://science.slashdot.org/article....id=160&tid=112)
said, "We wanted to use parachtues as a quick hack for the X-Prize, but
the
test range where we were planning to fly was going to require a half
million
dollars of "engineering support" and wanted us to carry a thrust
termination
system (bomb) on the vehicle to satisfy themselves that it won't drift out
of the range." Notice "bomb" in parentheses (his usage, not mine).

I think we have here another case of Rand attempting to push *his*
definition of a system on the rest of the world. Thrust termination which
does not destroy the vehicle will no doubt have a place in future reusable
launchers, but to insist that this is the only definition in the face of
industry usage is not reasonable.

IMHO, the above example you gave does not necessarily represent "industry
usage". It represents the wording used by the creator of the popular Doom
software (and now in recent past years having formed Armadillo Aerospace) to
describe the flight termination system for their vehicle. [What they are
doing seems pretty cool, and I regularly check out their web site at
www.armadilloaerospace.com.]

For specifics on historical STS usage of the term, try this:

http://history.nasa.gov/asap/1975-2-4.pdf

"Thrust termination" is referred to in the Abort section of the document
(right next to "ejection seats"), "flight termination" is referenced with
SRB destruction. [Note: I'm certainly not saying your definition is wrong -
because it's not.] In Sutton's book "Rocket Propulsion Elements" in the SRB
section "thrust termination" is even used to describe thrust control for
trajectory shaping (not a "bomb"). For manned systems (which is the context
in which we've been discussing), and in particular STS, "thrust termination"
was originally part of the (non-destructive) abort mechanism, but of course
was never implemented. The SRB flight termination system (as we saw in 51-L)
also included a destructive thrust termination system - that was a "bomb".

Jon

"Jon S. Berndt" jsb.at.hal-pc-dot.org wrote in message
...
IMHO, the above example you gave does not necessarily represent "industry
usage". It represents the wording used by the creator of the popular Doom
software (and now in recent past years having formed Armadillo Aerospace)
to
describe the flight termination system for their vehicle. [What they are
doing seems pretty cool, and I regularly check out their web site at
www.armadilloaerospace.com.]

For specifics on historical STS usage of the term, try this:

http://history.nasa.gov/asap/1975-2-4.pdf

"Thrust termination" is referred to in the Abort section of the document
(right next to "ejection seats"), "flight termination" is referenced with
SRB destruction. [Note: I'm certainly not saying your definition is
wrong -
because it's not.] In Sutton's book "Rocket Propulsion Elements" in the
SRB
section "thrust termination" is even used to describe thrust control for
trajectory shaping (not a "bomb"). For manned systems (which is the
context
in which we've been discussing), and in particular STS, "thrust
termination"
was originally part of the (non-destructive) abort mechanism, but of
course
was never implemented. The SRB flight termination system (as we saw in
51-L)
also included a destructive thrust termination system - that was a "bomb".

Great. You haven't told me anything I didn't already know. Now do a google
on thrust termination systems and look at the results. They almost
exclusively refer to those devices used on SRMs as part of the flight
termination system, and they all function destructively. You will find one
reference to a TTS for the Titan III/Dyna-Soar that actually applies Rand's
meaning.

This may seem silly, but I get tired of Rand's imperious declarations of
"fact" and snide put-downs. In this instance, industry usage does not
support his assertions that TTS only applies to non-destructive motor
shutdown.

-Kim-

"Rand Simberg" wrote in message
.. .
Last time I checked, Boeing was a major part of the launch industry.

Indeed they are, but they are just one part of an industry that uses a
broader definition of TTS than the one you put forward as the sole
definition.

-Kim-

Jon S. Berndt wrote:

In his Space Shuttle book, Jenkins states that the SRBs were designed
conservatively due to the man-rating requirement. SRB general safety
factors
were 1.1 yield and 1.4 ultimate - same as for Saturn V, according to
ref
manual AS-506. Testing showed these factors were met or exceeded.
Testing
that took place included tests where pins were left out, corroded
pieces
used, etc.


Of course the problem is that the stated design
margins, and the substantial qualificatoin
testing performed to prove those margins, did
not prevent the catastrophic field joint failure
from occurring on 51L.

Reviewing the CEV RFP, it seems that NASA will
eventually need two Constellation Launch Vehicles.
The first "CLV" will be used to orbit CEV. It has
to be ready to go by 2014. The second CLV will be
needed to boost much heavier payloads like the
Earth Departure Stage and the Lunar Surface Access
Module sometime after 2014.

CLV No. 1 is an EELV-Medium class launcher (10-20
tons to LEO), but it might not necessarily end up
being an EELV. It could end up being an all-liquid
EELV-derivative, among other possibilities.

CLV No. 2 is probably going to end up being in the
50-100 ton to LEO class. It might not ever need
to be "man rated". High thrust solid boosters,
a U.S. forte, could be applied. This big launcher
looks to me to be more likely to end up being shuttle
derived than CLV No. 1.

Time will tell.

- Ed Kyle

On Sun, 13 Mar 2005 05:48:29 GMT, in a place far, far away, "Kim
Keller" made the phosphor on my monitor glow in
such a way as to indicate that:


"Rand Simberg" wrote in message
. ..
I didn't know it was *my* definition. It's the definition of everyone
I know (e.g., at Boeing, on the OSP program) who talks about what is
necessary to human rate a launch vehicle. Any other definition leads
to great confusion.

Then you might want to take this up with the launch industry.

Last time I checked, Boeing was a major part of the launch industry.

"Rand Simberg" wrote in message
.. .
I put it forward as the only useful definition in the context of the
discussion (e.g., can the SRBs be safely shut down?). They don't have
a thrust termination system in that sense.

Agreed.

-Kim-