"Severed Nose Section?"

"John Maxson" wrote in message
...

Or the "forward cargo bay?"

http://www.datamanos2.com/challenger/image1.html

Minor nit. The velocity often cited for structural break-up is erroneoues.
The data source cited for the 2,900 feet per second was given for a Mission
Elapsed Time (MET) of 1 minute 15 seconds. That MET was never available to
Mission Control and it is actually from over four seconds earlier at MET 1
minute 11 seconds. Correcting this data disparity yields the real velocity
figure to be a little over 3,000 feet/second at structural break-up which is
2,045 statute miles per hour.

The altitude of nine nautical miles (54,684 feet) often cited is also
erroneous. At the time the Mission Control screens went static, the
altitude was really only 47,600 feet, thus Steve Nesbitt, the NASA launch
narrator, was off by over one nautical mile in altitude in his real-time
statement. The actual altitude at structural break-up was approximately
51,000 feet. This number corrects for the gain in altitude after the
screens at Mission Control went static at MET 1:11. My numbers are off a
small bit because I do not have the acceleration data for the unusual set of
circumstances the shuttle was encountering at the time it broke-up. For
instance we know that the SRB leak was causing a very small decrease in the
expected thrust along the normal vector. and that the hydrogen tank had been
leaking about nine seconds at a rate that could not be directly measured
(the hydrogen propellant level sensors are inactive until later in flight).
The effect of the hydrogen leak was to increase the acceleration of the
entire stack prematurely as the mass decreased in an unmodeled manner.
Finally, we have NASA's citation that the stack was destroyed by the LH2
tank failing at its aft end at the 2058 ring frame in a circumferential
manner and thus being forced into the intertank. I am aware of no modeling
of this final *acceleration* pulse if you accept the Roger's reports
conclusions.

Or the "crew module?"

Please don't ask us, ask the webmaster at the site you referred us to in
your post.

--

Daniel
Mount Charleston, not Charleston, SC

On Sat, 19 Jul 2003 10:55:25 -0700, "Charleston"
wrote:

Correcting this data disparity yields the real velocity
figure to be a little over 3,000 feet/second at structural break-up which is
2,045 statute miles per hour.

Is this indicated, calibrated, equivalent, or true?

Mary

--
Mary Shafer Retired aerospace research engineer

"A MiG at your six is better than no MiG at all."
Anonymous US fighter pilot

"Mary Shafer" wrote in message
...
On Sat, 19 Jul 2003 10:55:25 -0700, "Charleston"
wrote:

Correcting this data disparity yields the real velocity
figure to be a little over 3,000 feet/second at structural break-up
which is
2,045 statute miles per hour.

The maximum Knots Equivalent Air Speed (KEAS) Challenger experienced during
ascent is its own interesting story. NASA used the term KEAS in several
relevant 51-L FOIA documents, so I am quoting their use of the term for my
purposes here. The citation and quote below is from NASA's official STS
51-L crew transcript. The discussion below is between Commander Dick Scobee
and Pilot Michael Smith during the ascent of STS 51-L.

http://science.ksc.nasa.gov/shuttle/...transcript.txt

"T+1:02............PLT Thirty-five thousand going through one point
five
(NASA: Altitude and velocity report, 35,000 ft., 1.5 Mach).

T+1:05............CDR Reading four eighty six on mine.
(NASA: Routine airspeed indicator check.)"

If anyone cares to elaborate on KEAS, Challenger STS 51-L, and why the
numbers "four eighty six" are interesting please do so.;-)

Is this indicated, calibrated, equivalent, or true?

None of the above AFAIK. Real should read absolute, sorry. If you want to
start another thread on the ESMC range trackers be my guest.

--

Daniel
Mount Charleston, not Charleston, SC

"Charleston" wrote in message
news:1VpSa.22633$zy.3547@fed1read06...
"Mary Shafer" wrote in message
...

Is this indicated, calibrated, equivalent, or true?

None of the above AFAIK. Real should read absolute, sorry. If you want
to

Good grief. Note to self. Do not try to watch the Tour de France and post
at the same time. (OLN)

Let's really and absolutely try "relative velocity";-)

--

Daniel
Mount Charleston, not Charleston, SC

"Charleston" wrote in message

Minor nit. The velocity often cited for structural break-up is
erroneoues.
The data source cited for the 2,900 feet per second was given for a
Mission
Elapsed Time (MET) of 1 minute 15 seconds. That MET was never available
to
Mission Control and it is actually from over four seconds earlier at MET 1
minute 11 seconds. Correcting this data disparity yields the real
velocity
figure to be a little over 3,000 feet/second at structural break-up which
is
2,045 statute miles per hour.

I have seen a couple of different figures. The one I've seen most often is
in the PC report and cites M 1.92 at 73.3 sec. At that altitude on that
day, that purportedly corresponded to 1900 fps - NOT 2900 fps. That's 1300
mph.

The altitude of nine nautical miles (54,684 feet) often cited is also
erroneous. At the time the Mission Control screens went static, the
altitude was really only 47,600 feet, thus Steve Nesbitt, the NASA launch
narrator, was off by over one nautical mile in altitude in his real-time
statement. The actual altitude at structural break-up was approximately
51,000 feet. This number corrects for the gain in altitude after the
screens at Mission Control went static at MET 1:11. My numbers are off a

According to http://history.nasa.gov/rogersrep/v2appm.htm, the break up
(which started at just after 73 seconds) began at 50,000'.

small bit because I do not have the acceleration data for the unusual set
of
circumstances the shuttle was encountering at the time it broke-up. For
instance we know that the SRB leak was causing a very small decrease in
the
expected thrust along the normal vector. and that the hydrogen tank had
been
leaking about nine seconds at a rate that could not be directly measured
(the hydrogen propellant level sensors are inactive until later in
flight).
The effect of the hydrogen leak was to increase the acceleration of the
entire stack prematurely as the mass decreased in an unmodeled manner.
Finally, we have NASA's citation that the stack was destroyed by the LH2
tank failing at its aft end at the 2058 ring frame in a circumferential
manner and thus being forced into the intertank. I am aware of no
modeling
of this final *acceleration* pulse if you accept the Roger's reports
conclusions.

I find the ET "disgorgement thrust" a bit unbelievable.

Jon

"Jon Berndt" wrote in message
...
"Charleston" wrote in message

snip the now unreadable

Correcting this data disparity yields the real velocity
figure to be a little over 3,000 feet/second at structural break-up
which
is
2,045 statute miles per hour.

I have seen a couple of different figures. The one I've seen most often is
in the PC report and cites M 1.92 at 73.3 sec. At that altitude on that
day, that purportedly corresponded to 1900 fps - NOT 2900 fps. That's 1300
mph.

Sorry about that. You are correct, the 2,900 fps was erroneous to the tune
of about 1,000 fps not 100 fps. Today I recalc'd based on that error and
added from there. Der. In reality the 1,900 fps is closer to correct but
IIRC, it was still from the MET 1:11 data, as was the altitude of 47,600
feet, and Mach number of 1.92. I will see if I can find the final velocity
at 73.3 seconds directly from the Systems Working Group report. Does 1,972
fps sound better? wipes most of the egg off face but leaves some for
posterity

The altitude of nine nautical miles (54,684 feet) often cited is also
erroneous. At the time the Mission Control screens went static, the
altitude was really only 47,600 feet, thus Steve Nesbitt, the NASA
launch
narrator, was off by over one nautical mile in altitude in his real-time
statement. The actual altitude at structural break-up was
approximately
51,000 feet. This number corrects for the gain in altitude after the
screens at Mission Control went static at MET 1:11.

According to http://history.nasa.gov/rogersrep/v2appm.htm, the break up
(which started at just after 73 seconds) began at 50,000'.

I have seen that, but I believe it is off a little. Again, I think the
Systems Working Group, IIRC, nailed it at a little over 51,000 feet. I will
see if I can find that data. It does make you wonder why Kerwin quoted
48,000 feet in relation to his 207 mph water impact conclusion. Even using
the number you quote of 50,000 feet makes you wonder about the 207 mph
number.

snip

The effect of the hydrogen leak was to increase the acceleration of the
entire stack prematurely as the mass decreased in an unmodeled manner.
Finally, we have NASA's citation that the stack was destroyed by the LH2
tank failing at its aft end at the 2058 ring frame in a circumferential
manner and thus being forced into the intertank. I am aware of no
modeling
of this final *acceleration* pulse if you accept the Roger's reports
conclusions.

I find the ET "disgorgement thrust" a bit unbelievable.

As do I, but hell at the time it worked for NASA.

--

Daniel
Mount Charleston, not Charleston, SC

Damn, I thought this was a thread about Barry Manilow...:-)

Brian

--
Brian Gaff....
graphics are great, but the blind can't hear them
Email:
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"Charleston" wrote in message

"Jon Berndt" wrote in message

I have seen a couple of different figures. The one I've seen most often
is
in the PC report and cites M 1.92 at 73.3 sec. At that altitude on that
day, that purportedly corresponded to 1900 fps - NOT 2900 fps. That's
1300
mph.

Sorry about that. You are correct, the 2,900 fps was erroneous to the
tune
of about 1,000 fps not 100 fps. Today I recalc'd based on that error and
added from there. Der. In reality the 1,900 fps is closer to correct but
IIRC, it was still from the MET 1:11 data, as was the altitude of 47,600
feet, and Mach number of 1.92. I will see if I can find the final
velocity
at 73.3 seconds directly from the Systems Working Group report. Does
1,972
fps sound better? wipes most of the egg off face but leaves some for
posterity

I went back and read the AvWeek article from a week after the 51L accident.
Not that AvWeek should be viewed as authoritative, or anything, but it is
another data point to consider. I suspect they got their data from a
reliable resource. Anyhow, they say 1800 fps and 47,000' at 72 seconds. I
guess it sort of depends on what you call the start of the breakup process.
Was it when the right SRB lost its lower aft attachment, or was it when the
ET was breeched, or what? If we are talking about the point when the
orbiter was "liberated" from the rest of the stack, I guess that would be
at about 73.5 (rough est., but close). Given a 2g acceleration, that would
place orbiter velocity at about 1900 fps at 73.5 sec and ~49,000'.

I have seen that, but I believe it is off a little. Again, I think the
Systems Working Group, IIRC, nailed it at a little over 51,000 feet. I
will
see if I can find that data. It does make you wonder why Kerwin quoted
48,000 feet in relation to his 207 mph water impact conclusion. Even
using
the number you quote of 50,000 feet makes you wonder about the 207 mph
number.

Note that whether it's 49K, or 51K - that doesn't make much difference in
either the downrange travel or the terminal velocity.

FWIW, I calculated the terminal velocity as best I could using the following
figures (guesstimates):

CD: 0.87
S: 200 (sq.ft.)
H0: 49,000'
Gamma 0: 35 degrees above horizon
V0: 1900 fps
M: 1.9

The biggest variable was the weight of the crew cabin. I simply don't have a
clue how much that would weigh. The human weight in the cabin alone would
have been about 1,500 lbs. I estimate a low end for the crew cabin at
15,000 lbs total, and for a high end I would use the figire for the weight
of the X-38 - a pressure vessel meant for 7 people and also containing life
support, etc. That weighs about 25,000. That's my "high end". Here are the
downrange, terminal velocity, and time to impact values I got for those two
numbers:

For crew cabin weight of 15,000 lbs.:

downrange: 17,100'
velocity at impact: 269 fps (183 mph)
time to impact: 160 sec.

For crew cabin weight of 25,000 lbs.:

downrange: 26,500'
velocity at impact: 347 fps (236 mph)
time to impact: 140 sec.

Given the downrange travel figures I have read, the latter calculation may
still be fallin a few miles short.

I find the ET "disgorgement thrust" a bit unbelievable.

As do I, but hell at the time it worked for NASA.

I don't really see the evidence for that in the video record. In any case,
it's not really needed to explain the dynamics of the accident. I can't
remember what that was based on.

Jon

"Brian Gaff" wrote in message
...

Damn, I thought this was a thread about Barry Manilow...:-)

I was trying to get back OT. Sorry if I wandered. ;-)

Now I personally like Barry's singing voice pre-surgery. Which surgery you
ask? While some would argue that his voice improved after "Mandy", I could
not tell any difference personally and think it was still dandy. Now after
Copa, "Copa Cabana", there was definetly less, less banana....

--

Daniel
Mount Charleston, not Charleston, SC

On Sat, 19 Jul 2003 22:44:07 -0700, "Charleston"
wrote:

"Charleston" wrote in message
news:1VpSa.22633$zy.3547@fed1read06...
"Mary Shafer" wrote in message
...

Is this indicated, calibrated, equivalent, or true?

None of the above AFAIK. Real should read absolute, sorry. If you want
to

Good grief. Note to self. Do not try to watch the Tour de France and post
at the same time. (OLN)

Let's really and absolutely try "relative velocity";-)

I just wondered if it had been adjusted to a sea-level equivalent,
because of the miles per hour figure. That's usually equivalent.

Radar, then, I assume, and actual fps, not converted KCAS/KIAS.

The 486 kt would be KIAS or KCAS if it was a call-out from the
vehicle, not the radar trackers.

Mary

--
Mary Shafer Retired aerospace research engineer

"A MiG at your six is better than no MiG at all."
Anonymous US fighter pilot