http://www.stpns.net/view_article.ht...43251064362304
Gutierrez said the fault lies in two words - engineering arrogance.
"NASA engineers were confident that they did everything right,"
Gutierrez said. "They were so sure everything would work as planned
they didn't think an escape system was necessary. The fact is, if
there had been an escape system on Columbia and Challenger, the crews
could have survived."
Actually the design shortcomings of the shuttle system had been known
for along time before the challenger tragedy, (ie no crew escape system
for more than a small percentage of the crew if in place, and only
usable for a small percentage of the flight) and therefore it is the
responsibility of managers and engineers to operate the space shuttle
system safely within it's known parameters, (ie launching on jan 28
1986 was a managerial decision to launch in the coldest wheather
despite engineers recommendations not to launch, and inspite of
evidence of srb "o-ring" burnthrough on the previous launch
sts-61c). Roger Boijoly has been quite outspoken through the years
describing what happened to the challenger and how the disaster could
have been avoided, (his story can be found at onlineethics.org posted
below *5) describing the nasa managerial disregard to his (and
colleages) recomendations not to launch challenger and the sts 51-L
crew on jan 28, 1986 led to the tragedy. The push by nasa to make the
shuttle stack lift more payload weight was implemented with sts-8, by
modifying the solid rocket boosters. A srb thrust modification was
implemented to increase payload lift capability resulting from a
stronger solid fuel propellant coupled with a lighter rocket casing.
The rogers commission concluded the information demonstrating a pattern
of "O ring" burn through was available (*1), but this information
was not integrated into the decision making process by nasa managers,
Boisjoly and others were disregareded by nasa officials, and sts-51l
was tragically launched on the morning of January 28, 1986. STS-61a,
sts-61b and specifically sts-61c the programs 24th flight srb post
flight inspection completed on January 12, demonstrated a pattern of
obvious problems with srb casing burn through and o ring failures
(NSTS-22301 *3). STS-61C flight landed January 18, 1986, just 10 days
prior to the last flight of challenger, and the death of the sts-51L
crew. The two records set that ill fated launch day of Jan 28, 1986,
still stand today, the commonly known coldest launch temp of , and the
lesser known fact that sts-51l utilized a lightweight srb casing and
still was the heaviest shuttle stack to launch at 4,529,681 lbs (*4).
The rogers commission concluded the lightweight SRB casings aggravated
the "joint rotation", a spacing in the O ring seal area that would
allow the hot gases a path to the rocket casing if filler putty had
suffered blow through, a common problem. The O ring failure occurred
after nasa managers clearly disregarded the Morton Thiokol engineer
Roger Boijoly's recommendation to not launch, demonstrating humans
erorred in the decision making process (a failure mode not demonstrated
in the stated risk analysis). But another the fact is the lightweight
srb casings utilized for challengers ascent jan 28, 1986 launching the
heaviest shuttle stack ever used in flight history were concluded to
being "aggravating" to the O ring failure which resulted in the
death of the sts-51L crew (Rogers commission report chapter VII Casing
Joint Design) (*2)
citations
(*1)
http://history.nasa.gov/rogersrep/v1ch4.htm
The Dynamic Characteristics of the Field Joint Seal
"The discussion of static factors which affect joint performance is
based on the assumption that motor segments remain perfectly round, and
that stacked segments are always a perfectly straight column. At launch
the boosters are subjected to forces which bend and twist them. These
forces cause physical changes in the shape of the boosters, actually
squashing them out-of-round and bending them along their entire length.
The dynamic effects of this out-of-roundness are most significant just
after booster ignition when the hold-down bolts have been released
because in the previous 6.6 seconds the boosters have actually been
bent forward by the thrust from the main engines. The elastic energy
stored in the entire system is then released, inducing a bending
vibration in the boosters. This bending causes the case to change its
shape from circular to elliptical, the maximum out-of-roundness
occurring on the 045-315 degree line on the outside of the right
booster. This deflection is a consequence of a vibration and occurs at
a frequency of about 3 cycles per second. The same occurs in the left
booster, only the deflection axis is oriented differently, being a
mirror image of that which takes place in the right side. The dynamic
effects cause an increase in the joint rotation, and, hence, increase
the gap between the tang and clevis by about 10 percent. Another
dynamic load results from the geometry of the struts which attach the
booster to the external tank. Strut P 12 is attached to the booster at
about the 314 degree point and imposes additional inertial forces on
the booster which tend to additionally increase the gap by 10 to 21
percent."
(*2)
Rogers commission report chapter VII Casing Joint Design
page 192 & 193 par
"Upon ignition of the Solid Rocket Motor fuel the operating pressure
increases to 922 psi at 40 degrees F within a little over one half
second (0.648 sec).16 The effect of this pressure increase is to cause
the casings to bulge out around their midsections while being
constrained by the thicker steel sections at the ends, much like a can
of soda after freezing. The casings change shape during the buildup of
motor pressure. This bulging has an effect on the joint. As in the case
of the frozen soda can, the wall of the casing near the joint is no
longer vertical, or perpendicular to the bottom, but angles out to meet
the larger diameter in the center of the casing. NASA calls this change
in angle at the joint "joint rotation." This joint rotation is a
component of an overall spacing problem
that includes: changes caused by casing wear and tear experienced
during refurbishment; case growth (swelling) from pressurizing the
casings; distortion that occurs during shipment of the loaded casings;
and the physical handling of the casings during stacking operations.
The joint rotation problem was aggravated when the steel casings were
made thinner to achieve a reduction in weight and thus an increase in
payload. The rotation problem was further aggravated by changing the
design of the propellant geometry to achieve greater thrust. This
increased the pressure within the casings and thereby increased the
"gap opening"17. These changes compromised the integrity of the
joint seals because joint rotation increases the spacing (gap) between
the tang and the O-ring grooves in the clevis"
17. The Light Weight Casings, first used on STS-6, had thinner casing
walls than the standard steel casings. Light weight casings permitted
flight with heavier payloads. On STS-8, NASA began using the High
Performance Motor (HPM) which developed higher internal pressures while
using the light weight casings. The purpose of the HPM was to further
increase payload capacity"
18 , "Evaluation of TWR-12690 CD, Test Plan for Space Shuttle SRM
Lightweight inter Segment Joint Verification, dated June 10,1980", EP
25 (80-70), June 16, 1980, p. 2."
(*3)
http://ntrs.nasa.gov/archive/nasa/ca...992075284..pdf
NSTS-22301, page 4
"SOLID ROCKET BOOSTER
The STS 61-C flight utilized lightweight solid rocket motor (SRM)
cases. SRM
propulsion performance was normal and within specification limits, with
propellant burn rates for both SRM's near predicted values. Solid
rocket booster (SRB) thrust differentials were within specification
throughout the flight....
A postflight evaluation of the SRM structure to determine the extent of
damage
revealed the following significant items:
a. A gas path was noted at the 154-degree position of the aft field
joint of the left S_M. Soot was found from the 140-degree to the
178-degree position, and soot was found in the primary groove from the
68-degree to the 183-degree (115 degrees arc) position. C-ring
damagewas noted at the 154-degree position with a maximumerosion depth
of 0.00_ inch and erosion length of 3.5 inches. The 0-ring was affected
by heat over a 14-inch length in this area.
b. A gas path was found from the 273.6-degree to the 309.6-degree (36
degrees arc) position of the left S_Mnozzle joint. Soot was found in
the primary 0-ring groove over the entire 360-degree circumference. A
potential impingement point was located at the 302.4-degree point;
however, no 0-ring damage was found.
c. A gas path was found at the 162-degree point with soot in the
primary 0-ring groove from the lOS-degree to the 220-degree (112
degrees arc) point on the right SRM nozzle joint. 0-ring damage was
found at the 162-degree point with the maximum erosion depth being
0.011 inch and the erosion length being 8 inches. The 0-rlng was
affected by heat over a 26-1nch length in this area.
d. A gas path was found on the outer surface of the igniter at the
130-degree point of the left SRM. Soot was found on the aft side of the
outer Gaskoseal, approaching the primary sea! over a 70-degree arc (130
to 200 degrees), and on the outer edge of the inner Gasko seal over a
130-degree arc (ii0 to 240 degrees), however, no seal damage was found.
e. A gas path was found on the outer surface of the igniter at the
250-degree point of the right S_. Soot was found on the inside edge of
the outer Gasko seal over the entire 360-degree circumference, however,
it did not progress beyond the edge of the seal. There was a slight
discoloration of the metal on both sides of the seal over the entire
360-degree circumference."
*4
http://www.nasa.gov/columbia/caib/PD...BOOK2/G11A.PDF
page 105
*5
Boijoly's information
http://www.onlineethics.org/moral/bo.../RB-intro.html
Open sharing of information is crucial to improving everybody's
understanding of the universe around us.
Tom
wrote:
Remember the question why NASA did not release their results on the
in orbit repair options for Columbia? It seems the results were too
unwanted obvious:
http://www.stpns.net/view_article.ht...43251064362304
Astronaut Talks Of Shuttle Disasters, Life In Space
By John Larson for Mountain Mail, November 09, 2006
Both space shuttle disasters, Challenger in 1986 and Columbia in 2003, could
have been survivable, said former NASA astronaut and aeronautical engineer
Sid Gutierrez of Albuquerque.
...
As an Air Force instructor, fighter, and test pilot, he flew over 30
different types of airplanes, sailplanes, balloons and rockets. He
logged more than 4,500 hours of flying time. Gutierrez is a native
New Mexican born in Albuquerque, and currently a department manager
at Sandia National Laboratories.
...
Gutierrez said the fault lies in two words: "engineering arrogance".
ôNASA engineers were confident that they did everything right,ö Gutierrez
said. ôThey were so sure everything would work as planned they didnÆt
think an escape system was necessary. The fact is, if there had been
an escape system on Columbia and Challenger, the crews could have
survived.ö
...
As a NASA astronaut Gutierrez was pilot of Space Shuttle Columbia on
STS-40 in June, 1991, and commander of Endeavor on STS-59 in April, 1994.
In February 2003 Columbia disintegrated above Texas while re-entering
the earthÆs atmosphere.
ôIf the engineers at NASA had looked closer at the video that showed the
foam hitting the orbiterÆs wing, the crew could have done something about
the hole in the leading edge of the wing once they were in orbit,ö he
said.
He said something as simple as wet towels forming a several-inches-thick
layer of ice would have been enough to keep hot gasses from burning into
the crack in the leading edge.
ôThere was no escape system in place on the Columbia, either,ö Gutierrez
said. ôThe breakup started at about 200,000 feet. With oxygen masks, the
crew wouldÆve at least had some chance at surviving if theyÆd had a
parachute system.ö
He said the shuttle is the most dangerous space vehicle ever flown.
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