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Shuttle Disaster

Shuttle Disaster

Shuttle Disaster

(OP)
Is it true that the foam insulation that struck the shuttle wing was going +500 mph??  (According to the reports on CNN anyway.)

At the time of the foam separation, both the shuttle and the insulation were moving at the same velocity.

When the foam insulation separated, did its velocity slow enough in that short time (between separation and impact) so that the relative velocities of the shuttle and the insulation exceeded 500 mph?

Can someone explain this to me?

RE: Shuttle Disaster

KLH,
From basic aerodynamic theory (bernoulli), air/fluid flow increases speed as it flows around an obstacle (eg aerofoil) such that the velocity of a particle in the flow is travelling faster than the aerofoil itself, the freestream velocity. Im not sure what part of the shuttle the foam came off, but it seems that a likely explanation is that upon separation of the foam from the shuttle, the foam is accelerated to the velocity of the air flow around the shuttle. As the foam has a lot more momentum (density, mass) than air, it has more trouble getting out of the way of the looming wing than the air does, assuming subsonic conditions. If supersonic conditions, the foam would have no prior 'knowledge' of the coming impact with the wing, and therefore not divert its course at all (unless it hit a detached shock).

Hope this helps & I made sense.

Cheers,
tsurani

RE: Shuttle Disaster

Here's a little more to think about, I checked and the shuttles relative speed after a minute as around 1000 mi/hr and after two minutes it's 3000 mi/hr.  The foam separated at T plus 80 second so I'm guessing the shuttle was traveling in excess of 1500 mi/hr.  I believe the foam came off above the upper mounting bracket for the shuttle.  It would have to do with figuring the distance the foam traveled, the relative speed of the air flow, size of the foam and weight of the foam.  Throw a styrofoam cup out the window of your car and look at how fast it goes by the bumper, then go pick it up.  Maybe this helps.

RE: Shuttle Disaster

NASA has bigger problems than foam insulation. The original shuttle design did not reflect any proper and competent calculation of mechanical transients. This caused the Challenger accident and is the likely cause of most of the structural damage that the shuttles have experienced over the years.

The evidence is substantial.

RE: Shuttle Disaster

I thought it was the poor design of the O rings that caused the Challenger disaster?
A

RE: Shuttle Disaster

Actually, in both cases, NASA management violated the original operational requirements:

Challenger:  No launches at low temperatures
Columbia:  No foam strikes on the Shuttle

So, as with tipsy SUVs, design compromises can be compensated for by reductions in operational range.  When that is violated is when you run into trouble.

While it's easy to use 20/20 hindsight, we as engineers should and must recognize that technical challenges almost always result in design compromises and "imperfect" designs.  If it were that easy to come up with a "perfect" design, you wouldn't need an engineer to do the job.  The engineer makes the technical trades and compromises to solve the end problem as cleanly as possible.  

TTFN

RE: Shuttle Disaster

The failure to properly calculate the transient loads is a 70 to 100% error (depending on where on the shuttle you look). NASA never understood this. It's a colossal blunder. 70 to 100% structural loading miscalculation! It also means that the payloads have be subjected to 70 to 100% greater g-forces during prelaunch, than they we designed for.

RE: Shuttle Disaster

>The original shuttle design did not reflect any proper and competent calculation of  mechanical transients.

> The failure to properly calculate the transient loads is a 70 to 100% error

Some pretty serious generalizations/accusations here.  Any evidence?

RE: Shuttle Disaster

Post your email address and I send you a report.

RE: Shuttle Disaster

Me too if possible, my boss worked on some aspects of the design.

RE: Shuttle Disaster

I would like to see the report of which you write, JimMetalsCeramics.

loralechago@yahoo.com

RE: Shuttle Disaster

Everybody get the report? Any reactions?

RE: Shuttle Disaster

OK Jim, I'll bite, please send it to me at

greglocock at yahoo dot com dot au

Thanks

 

Cheers

Greg Locock

RE: Shuttle Disaster

JimMetalsCeramics,

Without putting you to too much bother can I get a copy also?  I am at scotland6@bigfoot.com.

Regards

John

RE: Shuttle Disaster

That report...

Hmmm.

So far as I can tell it is based on this quote "The effect of a suddenly applied force is stated clearly in some textbooks. In Shigley’s Mechanical
Engineering Design, we find: “when the load is applied suddenly but without initial velocity … the stress
is twice as large as that caused by a gradually applied load,”

If so (I haven't read the whole thing) then he has misunderstood dynamic analysis very badly indeed. Shigley's force doubling applies for one specific design of beam (a particular damping factor, in fact). It is not a general result. How can you instantaneously apply a load without a velocity, in the real world?

If he relies on this force doubling all the way through then he seems to be a nut.

Later quote:

"Strangely, the doubling effect is not mentioned at all in aerospace design textbooks and handbooks, and
the consequential effect is almost never mentioned in peer-reviewed scientific and technical papers. This
may explain why the devastating effect was neglected in the design of the Space Shuttle and other
systems. The oversight may also explain many failures of rockets, spacecraft and space probes since the
beginning of the space program in the 1950’s."

Nut. It isn't mentioned because it does not generally exist.

His later chapters seem to be quite interesting, in their own right.

Cheers

Greg Locock

Cheers

Greg Locock

RE: Shuttle Disaster

I kind of felt that the report was almost of a religious nature and he's gonna start telling people that Dianetics is the way and so on so forth. I just don't see how if this is such a HUGE problem then it isn't treated in practice or textbooks.
T

RE: Shuttle Disaster

That's easy to answer:

Because, He is the ONLY person with the correct insight.

TTFN

RE: Shuttle Disaster

Read sections 7 and 8.2 to 8.5. The phenomenon is real, it really did occur and it was neglected in shuttle design, despite your protestations.

AbuTaha has been an aerospace mechanics expert for over 30 years. The documentation shows that the phenomenon really occured. In fact, this is the easiest argument to make. If you don't think the phenomenon exists and is applied to the shuttle, then how does 1.1 million pounds of thrust from the main engines acting upward, and 200,000 lbs (the weight of the orbiter) acting downward, at a distance of 400 inches from the SRB centerline, generate a maximum measured base bending moment of 700 million inch-pounds?

Why does the vehicle lurch forward substantially past its steady-state defelection point?

RE: Shuttle Disaster

One issue I have is that he's using model rocket thrust characteristics as "proof" of dynamic overshoot, while NASA's page http://www.grc.nasa.gov/WWW/K-12/airplane/rktengperf.html on model rocketry clearly shows the same data, but alludes to flame front characteristics. which is a design parameter:

"Designers of solid rockets can produce the given thrust curves by changing the total amount of propellant placed in the engine, by varying the the angle of the cone in the propellant, and by varying the diameter of the propellant (and casing)."

He then compares the model rocket test data with Thiokol test data and says that NASA "missed" the dynamic overshoot.  BUT, since Thiokol's data is also measured data, he fails to explain why the test data does not show dynamic overshoot.  

The simple interpretation is that Thiokol probably designed the SRB specifically to eliminate the thrust overshoot, since that appears to be a very well known phenomenon of solid rockets.  

This is particularly relevant since the SRB does not use the same physical design as a model rocket.  A model rocket simply burns from the nozzle forward, while the SRB is a hollow core motor that is ignited along its entire length and actually burns radially, thus signficantly altering the flame front and the thrust characteristics.

TTFN

RE: Shuttle Disaster

The excess thrust comes overwhelmingly from transient response and not propellant geometry. Insofar as overshoot being well known; this information, and the acknowledgment of the initial mistake have never been disseminated. Thiokol signed off on the o-ring joint failing on Challenger.

In short, the key areas of stress on the overall launch vehicle are those directly impacted by main engine and SRB thrust. Overshoot occurs during start-up and during engine throttling (during flight). The structural design of the shuttle not only was void of proper understanding of excess effective structural forces due to transient response(ranging from axial tension on the SRB housing to various truss and strut components between the SRBs and the orbiter), but this omission perfectly explains numerous cases of vehicle and payload damage going back to the beginning of the shuttle test and flight history.

RE: Shuttle Disaster

Jim, his misapplication of the quote from Shigley is just plain wrong. Force doubling is NOT a general property of dynamic systems.

I have no problem with high forces being generated as a result of excitation of resonances... it has been my bread and butter for 25 years. But given that NASA had performed a full modal analysis on the shuttle 27 years ago I am reasonably happy to assume that they have a dynamic model that will model 'overshoots' (transients would be a more usual terminology). It is not, if you will forgive the phrase, rocket science.

Cheers

Greg Locock

RE: Shuttle Disaster

Greg,

NASTRAN has no transient response module. I have found this matter to be puzzling to engineers, even those working in aerospace(I am familiar with this matter for 15 years now). Certain conditions must be satisfied in order to have dynamic overshoot. The key one is that the system be under-damped.

Is it your contention that there is no first order overshoot of the system response to the SSME and SRB thrust?

RE: Shuttle Disaster

I'd also like to add that the manner over the years in which extensive structural damage to the launch vehicle and failure of payloads taken into orbit, has been sloughed over and rationalized is disgusting.

RE: Shuttle Disaster

"NASTRAN has no transient response module."

Yes it does. Time domain modelling based on known force signals is routinely performed all over the world by thousands, if not millions, of people.

I'm not an FEA dude, so I can't tell you the exact commands but, roughly, build FE model, do a static analysis, correlate, do a dynamic analysis (to get the frequency response functions), correlate, build time based force signals, apply to dynamic model, look at pretty pictures on screen.

We then take those time varying stresses and do a fatigue analysis using them.

This is so fundamental that I think I must be misunderstanding what you are talking about.

"Is it your contention that there is no first order overshoot of the system response to the SSME and SRB thrust? "

No. I am saying that the tools to analyse this have existed for decades and that it is a well known property of systems.

Cheers

Greg Locock

RE: Shuttle Disaster

If "proper" analysis exists in NASTRAN then this is new. I've had dynamics experts in industry admit that this topic was not properly taught until the early 70s. I had a former undersecretary of Defense tell me that it was clear to him when he attended early shuttle tests that NASA was lost on the mechanical behavior of the system.

The omission of correct transient response from the shuttle design is clear. Let's look at two simple examples from the paper.

Section 7, pg. 23, Fig. 15

This represents data from a flight readiness firing test (FRF). The main engines are ignited and the SRBs are held down. The holddown posts have strain gauges on them to record the force from the main engines.

Using three different calibration methods, the test engineers measure "EXCESS UPWARD FORCE" in excess of 500,000 lbs.

Pg. 24, Fig. 16, "MEASURED DATA QUESTIONABLE -- TOTAL (DELTA) LOAD > SSME THRUST"

Pg. 28, Fig. 17, "REQUESTED OF LEVEL II A VERIFICATION OF THE PRE-IGNITION 1-G CALCULATED LOADS

They are clearly expecting to measure, according to their specification books, a force equivalent to the maximum applied steady state force from the main engine thrust. They see the correct experimental force which includes a roughly 50% overshoot (not the applied force but the system response). They are bewildered.

Section 8.4.  Figures 27 and 30. When comparing the two plots for the same measurement, both the max and min numbers for bending moment vs. time are irreconcilable.

Throughout the published shuttle specifications the values you will find are for maximum applied force, sometimes with up to a 14% dynamic factor added.

RE: Shuttle Disaster

I don't know exactly how or if they relate to each other but when designing for a shock load, specifically a half sine pulse, the safest approach for a dynamic system is to double the static load.  This is a cover all and the actual amplification factor depends on the system natural frequency and damping coefficient but it can never be more than approx. 1.8 times the static load.  This allows for an overshoot (apparent increase in force) just after it is applied.
I can't believe that engineers at NASA don't work with something along these lines when doing the mechanical design of the rockets on the shuttle, it is fundamental.

Oh and the report makes interesting reading.  I am working my way through it!!

RE: Shuttle Disaster

May I have a copy of this report as well?

sts_1OO@yahoo.com the "OO" are letters O's not number zeros. thank you, I appreciate it.

"Man is the best computer we can put aboard a spacecraft... and the only one that can be mass-produced with unskilled labor. "
        -Wernher von Braun

RE: Shuttle Disaster

JimMetalsCeramics,

Could I still get a copy? Sorry so late, forgot to mark the thread.  

dpadler1@yahoo.com  

RE: Shuttle Disaster

I have used Natran for dynamic analysis for fatigue proofing. It is capable of dynamic modelling, but you have to know the velocity as a function of time (seismic mass method). This is difficult if the system is an SRB in the process of being lit-up.

I used to be a non-linear (explicit) FEA guy, so I always mistrust linear results. The norm is to use a half sine pulse, which assumes an upper frequency limit to the dirac (shock) function. This is a fair assumption, since higher frequencies tend to get "absorbed" by any structure.

The big problem comes from the assumption of linearity. The Poisson distribution has already proven to be a mislead to the shipping industry in statistical expectation of ocean wave sizes (turns out to need Schrodinger wave equation to model accurately). Add to that the fact that the structure will deform as a result of vibrations, likely to be large with high tensile materials, and the assumptions soon add up.

I have no read this report, but a statisticion friend of mine used to have grave doubts about the validity of the 6-sigma approach for ensuring that gas turbine white noise vibrations actually gave as little as 0.04% (from memory) that the wings would fall off!

In practice what this really means is that the material ages through fatigue sooner than the calculations would suggest. Basically as the aircraft ages, structural problems will appear sooner than they ought. This tends to affect panels more than say structural members, and could explain why occasionally panels fall off!

Just my thre'pence ha'penny...

Mart

RE: Shuttle Disaster

GraviMan has got it. This is a case of low cycle fatigue. The history of the shuttle launch vehicles has been riddled with both major, single launch component failures which are forestalled through empirical strengthening of the system, and low cycle fatigue of components far earlier than initial calculations would have predicted. Everyone asks, if this mistake was made, why doesn't the shuttle explode on every launch. This is because:

1) Systems are spec'ed to minimal material property values,

2) There are finite safety factors, albeit inadequate for long term use, built into the shuttle vehicle structure, and

3) The system has been empirically strengthened over the years.

In the latter case, the SRB segments, for example, are held together with 1" diameter bolts. This necessitates that hole spacing be at least 1.5" (it was 1.51") from edge-to-edge in order to avoid one tear out event leading to the adjacent hole and so on. After initial failures of these joints (no doubt due to excessive axial force transients) extra 1" bolts were added between each initial one. Now the spacing is 0.25". OSHA, let alone a pressure vessel designer, would jam on the brakes.

RE: Shuttle Disaster

Thanks JimMetalsCeramics.

Any chance you could bung the report to
martingarrish@aol.com ?

I'm starting to feel left out not having bitten yet!

Mart

RE: Shuttle Disaster

Any more responses to the report?

RE: Shuttle Disaster

  In May 1988 Ali AbuTaha's Spaceflight Cover article forecast the Columbia Loss.
  Personally, I believe Challenger died for a different reason, however, as his calculations showed areas of the vehicle would have pre-existing metal fatigue my own mechanism -- small explosions in the fuel prompted by over-fast5 drying -- would result in tongues of flame emerging, preferentially, just above the struts that transmit the sideways overstrain (vertical strains are all higher by 40% later in flight because "vacuum thrust" is higher and this, plus 10%, was assumed to cancel the transients but a 1981 launch timing change was not a full redesign and missed that sideways stresses have no such extra 40% -- in 1970 they Launched after 1 second of SSME testing not 6.6, so the vehicle never bent all the way over --Ali wanted to change back but a launch partly bent over might jam one of the SRB clamps; the Companies adopted new Requirements for higher structural strength in effect ENDORSING his claims in 1989 -- Congress refused to spend money to change anything but the new AL-Li ET must meet them as it has only half the expected cargo gain) ...
   Now image YOU are a Shuttle --orbiter on your back, Solids your arms: the easily seen flame comes out of your wrist about half forward (35 and 37 degrees) hitting the ET just right of the belly button --- but there are two struts, and a flame came out angled BACK about 37 degrees from directly facing the ET, hitting the Right wing Aileron on the underside of the Right wing (note similar damage on both wings on STS-56, -90, and -107, -90 considered Most Similar Mission to -107 as they both had the same weird 1-push Wind Shears) ... now this impact is AT THE SAME MOMENT that Challenger responded to something the Rogers Commission VOTED was a Wind Shear, however, when they finally figured out Wind Shears at the Weather Bureau 2 years later: all such were circular: there should be a Paired Shear in the opposite direction.
    There isn't.
    Instead, on fetching Challenger pieces from the missile silos out West where they were stored, they found a fist-sized burn through EXACTLY at the point of impact expected from the PICTURES of the flight -- which Ali was able to find for the furious Weather Services (cf Young's tirades against them for killing his friends by not forecasting Challenger's Wind Shear & CHUCK YEAGHER'S BOYCOTT OF THE CHALLENGER MEETINGS AFTER THE COMMISSION ORDERED NASA TO STOP LOOKING AT PARTS OF THE FLIGHT THAT DID NOT ADVANCE THE O-RING THEORY).
   Now as Columbia was also launched in a Florida Drought (with SUVs falling into sinkholes) AND just after a Deluge --just like Challenger -- one should expect a similar hole &
so we see the hole in Columbia's elevon actuator -- the Only piece where the new commission did NOT tell reporters "we have to wait for the chemical and other analyses" but dismissed it as occurring AFTER the breakup (Challenger's hole did NOT match other post-breakup heating and anyway from the moment of impact that Ali discovered her motions clearly matched the the way a computer would double-correct for motions with a control surface damaged -- not applicable here).
   In short, had Challenger not had a hole directly facing the ET, and so reached orbit (yeah, the ET did not even break up from opposite the "joint that failed" but higher up the side where a welded seam on the Solid obviously busted)....
     ... its reentry would have seen the wide area around the burn-through, where heating makes the aluminum less stiff, flex the wing resulting in breaks where it adjoints the almost unbendable RCC panels at the front of the wing, ON THE TOP of the wing.
     Now the insane parts of the Columbia Scenario are explained: the STRESS sensor goes first because STRESS breaks it, the TOP of the wing loses pieces at 340 seconds changing the airflow (yet all this is "caused" by a breach at 487 seconds over TWO MINUTES later (!)), the wires all die from the TOP down, the farthest west piece is from the TOP of the wing, the carrier panel directly behind and adjoining #8 lower (the foam impact point) is the LEAST damaged piece in that zone of the wing but #8 carrier UPPER is one of the MOST , Carrier Panels #9 Upper #10 upper, #11 upper are all missing but ALL of the Lower carriers were found by the Debris sorters at a time when it was admitted the orbit object HAD to be a carrier panel (after which we get excuses)... etc etc etc.
    Ali's strut-transmitted overthrust causes overpressures in the SRBs to squirt out in a hideously dangerous direction.  After patches of insulation melted on STS-56 indicating 1000 degrees (despite never exceeding 200 in either models or on a similar inclination flight) -- at 1100 degrees they die -- the other 3 Shuttles had heavier insulation put on (not Columbia) (not on a wide enough area for so severe a heating incident, probably).
   I would: (1) not launch between 1 and 30 hours after a rain  (2) start 1 engine 8 seconds before the other SSMEs  and Launch 1 second later (+800lb cargo) (3) Provide Intact escape off the Solids using an Idle mode (+22,000 pounds with Centaur OMS) (4) Rehire the fired Scientists (why do you think they had to contract for Boeing to look at the Foam Problem?) (The OMB took over NASA recently (Sean "NASA doesn't need any new starts" O'Keefe), just like the NRC in 1985/6: wipe out the good parts, a shuttle blows, convene a panel containing ZERO Rocket Scientists --- and the next time, the SAME mechanism could kill via a fuel leak -- which clearly happens here cf the sensors that failed after FALLING temperatures showing LH2 pooling in the back of the wing, or aero-force breakup early due to the associated MISMATCH of SRB thrusts (STS-25 -107).  Consider the Universal Electrical Failure 2 seconds after the epocal restabilization STS-107s Pilots managed 30 seconds after half the left wing broke off -- LH2 explosion in fuel cell area??? -- other wise they live to bail-out altitude (?).
  Finally the economy responds to INFRASTRUCTURE -- when Clinton cut NASA's Space Science by a factor of 2.5 in 2 years, 5 years later all (major) new developments in Computer stopped & the Market crashed....
    So for goodness sakes keep NASA at at least HALF JFK's level -- it means $220 Billion a year in the 6th year after, 444 the next 650 the next etc.  Comments?

RE: Shuttle Disaster

CusterWillson is correct. Challenger exploded because the flame from the right solid rocket booster was aimed at the external tank. The hole in the right SRB was certainly not caused by o-ring blow by (NASA's story) but by a gaping hole torn in the right SRB aft joint due to bending moment stresses exceeding design values (the previous flight damage to the right SRB set up STS-51L to be the mission where the full-blown failure occurred).

Even without the extension of time between main engine ignition and lift-off, there are excessive forces all over the launch vehicle. These include SRB ignition thrust and g-forces acting on the payloads. In the latter case, the excess g-forces would exceed design values that the payload designers were given to design to.

Transient response creates over-stress conditions all-over the launch vehicle. The overstress is generally 60 to 100% greater than the steady-state forces. If you can believe it (and even if you cannot) the launch vehicle was designed to maximum steady state loads with a dynamic loading factor of 14 to 40% used. Given the fact that the transient overshoot exceeds these values, the Challenger accident was a metallurgical/structural catastrophe in the making. Since the problem was never fully recognized and corrected, it must be presumed that it was a primary source of structural damage (including insulation break-up --- if that's was really the ultimate culprit) on Columbia.

RE: Shuttle Disaster

   Challenger was killed by the small explosions in the fuel called "Combustion Instability". However of the 7 known holes in Challenger's side 5 clustered at spots (the struts) Ali calculated overstresses at -- and (see the pictures in the May 1988 Spaceflight) one of these burned a hole in the wing which WOULD have killed her.
   Columbia was killed by an almost identical hole except in the left wing -- the explosions using the weakened area as a preferred path was an accident waiting to happen.
   Columbia was thus killed by the Challenger Panel Majority, who buried the details & ended their "Final Review" in mid-April the day before even the chemical report on the first joint piece was available (guess what: they found NO O-ring markers in the soot.  They never leaked.  That flight.  The critical ananlysis of cracks in the ET was dated 3 weeks later.

   Now Combustion Instability has: blown holes in 3 of the 4 Shuttle-equivalent Expendables, almost killed Challenger earlier in its flight by a thrust mismatch nearly flying it sidewise to the wind -- and a mismatch occurred again on Columbia.  Also (see my replies at the end of the  other 2 Forums (use keyword Columbia) the SHAKING probably caused LH2 to migrate past valves in the fuel cell interconnect system, blowing the electrical system on Columbia and foiling the gutsy Pilots' restabilization of Columbia 30 seconds after the wing broke in half --- in this I am cribbing NASA's research on the last large Mars Mission (Mars Observer died from a fuel migration-past-valves problem obviously the result of violent SRB shaking).

   Ali's Transient overstresses can also kill directly.
Ripping the 2068 ET seam should kill about 1% of older ETs; Accellerated wear-and-tear is Constantly being uncovered (I am glad Ali broadened his argument since last I had contact -- I pointed to the Main Engine bearings: but I had no idea there was so much more.
   Nonetheless there is not as much as you believe:
    1. Companies typically add 40% to ALL strengths, fearing becoming a WorldWide Pariah like the Apollo 13 Low bidders.
    2. Liquid Thrust is 40% higher at altitude.
    3. 10% was added to account for Transients
        --- note, not assessing them was sloppy, but the whole Moon program was a race between the USA upgrading fuels & the USSR increasing engine pressure -- the Shuttle combines BOTH, and the jump to a high-pressure engine resulted in SURPRISES -- such as a 59% overrun when 10-15 was experience.  Similarly "Escape off the Solids" always assumed the Liquds would shut instantly because they always had ... Challenger's orbiter's near-escape on only 1 engine shows how easily one can use them for escape and, in Idle mode & with Centaur CH4/LH2 OMS (Lunar & Zubrin's Mars Direct landers could use the SAME engines) for up to 22,000 lb net cargo (with the Al-Li ET, 4000 lb to "108-degree reverse Sun-synchronous (Military) orbit" becomes 33,000).    
    4. Standard 15% margin (40% where poorly understood).
    ... now Thiokol used the latter, +40% = 194% strength or 94% margin vs 70% Transient for the Solids ... Liquid stresses used 115% x110 (x140% for thrust), x140 = 248 or +148% margin vs. 59% -- but only 77.1% for sideways thrusts where +40% thrust, does not apply.
     ... now the welding flaws in seam 2068 halved the usual 40% Company extra, which was informal & optional, after all (ie they were 20 & 30% stronger than NASA specs) ...
     ---NOW NOTE WELL:  attempts to use expendables to fly Shuttle-sized cargos DO NOT have that extra 40% margin (of course they also rarely have a 3-legged cross-stress) which explains why only one ever reached orbit -- and at that a VERY low one -- and all have had their cases thickened to where they can not take the large Miltary Satellites. --
  
     Now if Challenger's  descent to 20% margin was closer to the strut: Goodbye on the Pad ... as it was, the cracks came from above & went Through the flaws, but it still caused That seam to split Prior to the one above where the ET's problems started.   That bouyed the Commission argument that flames from the visible O-ring hole hit the ET at the repressurization line, melting the tank yet dropping the Pressure (the line is on the BACK LEFT but they argued the vehicle is flying upside down -- kind of like saying when you turn around ONE of your eyes moves to the back of your head) (Feynman disagreed, suggesting SRB hole gasses which cut Strut strength in half broke it which compromised tha ET in a vague way --- BUT, the strut broke on the (unheated) ET side, implying an IMPACT faster the speed of sound in metal, i.e. ejecta from a hole higher on the side (not unlikely the very chunk of fuel whose shrinkage caused the pressure spike that blew out the side and pierced the ET -- Challenger had a LOT of ground damage from such chunks).
      In short, both the fuel problem, & Transients, have to be avoided or fixed --
       ... there are MANY possible accidents if these two root causes are running wild, enough for the Bureaucrats to claim the next 'doesn't look the same' so it is "another NASA slipup", EVEN THOUGH vitually identical damage happened to both Challenger & Columbia, damage which any REAL investigation (not one excluding Rocket Scientists) would not have buried, but FIXED.
    My nightmare is losing all 5 Shuttles, ALL blamed on "NASA" if there is 1 of each of the accidents I have cited above (hole by strong explosion, hole by moderate explosion POINTED at wings by weakened area near strut, thrust mismatch, ET seam rip on pad (the only one to be fixed -- partly: struts still might break), and: repeated explosions migrating fuel past valves.
    Remember, the same man headed ALL investigations at NASA until fired by the Challenger Commission Majority, first day.  Also that Rocco Petrone cancelled Challenger's Launch --the people who Fixed the Panel evidently ordered he not be informed when they called everyone else back but it appears in records because he assured Thiokol their inability to get good calculations ruling out the Cold should not dismay them -- he'd already planned to cancel it (at least partly for the Right reason: it was too much like STS-4 when they lost both solids & shook so bad any cargo would have been glitched, plus the Low orbit from Low SRB performance we saw again in Columbia & the Delta lauched just prior to it .. literally, he said "too many things close to the edge").
      So I consider the Institutional Cause of the accident is not NASA but the EXCLUSION of the non-politicised Hard-Science NASA people, the Congressional elimination of NASA's Overrun Protection, the cut by a factor of 13 in Space Science, the loss of the NASA Administrator's Reserve, and the constant cancelling of critical upgrades ostensibly for Budget reasons, but often because FIXING anything means Admitting a Mistake...
 
      But, again, Transients "only" caused fatal damage to Challenger.
      A simple fuel explosion inside the SRB, blew her ET.
      Before the Transients could kill them ala' Columbia.

      Columbia saw the mainly-Transient-caused, back-of-the-Wing-roasting, return, to preempt a possibly fatal Fuel-cell leak.
       -------------

      ... in re Shuttle sucessors -- I love SSTOs, but they run so close to materials technology limits ... will Transients be too much, since the extra 40% the companies have tacked on our Shuttle looks impossible?
      Or will air-launch or slow thrust-buildup avoid the Transient problem?        

RE: Shuttle Disaster

CusterWilson,

Do you have a copy of DesignError.PDF?

RE: Shuttle Disaster

   Jim: I was thinking of requesting it though at first I thought I had it directly from Ali in hardcopy 14 years ago; yours seems to be a bit updated (at the time Ali was perhaps overly concerned with the ET seam busting at Launch whereas wear on the main bearings, etc, provided so many routes not even just to destroy, but to degrade Shuttles -- i am afraid I am somewhat callus in considering Program Slowdowns in the same breath as Fiery Astronaut Deaths but ... the Lifespan Effects of a lack of Exploring are 1 Billion years/per/year or 15 million equivalent Lives, by my count (the difference between .3 years gain per year & .1 year/year).
     So: I need one, but tell me how to retrieve it, I am new to post-Dos tech & my cable service stores the E-mail: I can read it, or connect to the source & download but it doesn't go direct (? or am I misinterpreting).  So explain a bit or show me a site I can save from.

     And one REALLY powerful thing you could do is if you could find Ali himself for me -- I have tried Web searches but it seems like he is not on-line.
     That stuns me: like: he called this! The Proximate Cause .. we have a Picture of it (a red flame seen through the crack between the wing of Challenger & her aileron, see his article May 1988 Spaceflight (I had a letter in June 1989 -- so far as I know these are the Only dissents to the Challenger PAnel's Explanation.   If the Columbia Panel was Honest they would have HAD to include him, and maybe even me, just on that basis (ignoring Feynman's vaguenesses))).  

RE: Shuttle Disaster

If you post your email, I'll send you a current copy of the paper.

RE: Shuttle Disaster

Falling debris may have caused the pivotal damage on Columbia (I don't understand how such large relative velocity was generated so quickly, though). But there is a widespread problem that the pre-launch, launch and in-flight loads were inarguably, severely undercalculated. Any avoidance of this issue is a whitewash.

RE: Shuttle Disaster

The Columbia failed due to an impact of foam on RCC panel 8 or 9.  The foam was traveling at 500-600 MPH.  Currently the number being evaluated is 545 MPH. This speed was the result of a drop in velocity of the foam due to aerodynamic drag forces. (rather large in shape but, light like a feather) which broke off at ~1800 MPH.  When it hit the wing it was traveling at ~1200 MPH.
 
Tests at Southwest Reaseach Institute consisted of shooting a piece of foam at panel 8 at 1100 ft/sec and it blew a hole into the leading edge that was 12"x15".  Clearly this proved that the foam was capable of causing the damage that would allow the 3000 degree rarified gas flow to melt the wing structural components.  By that way, this was all on a CNN special which I guess everyone missed.  If you really want to find out how NASA engineers  tested, evaluated, and determined the root cause of the Columbia disaster take a look at this web site:

http://www.caib.us/news/report/default.html.

RE: Shuttle Disaster

    The CAIB rigged the test 3 ways:
    # 0. They DID use real foam against a real RCC panel, at the real speed ... BUT:
    #1. Despite Cameras showing the Foam breaking up into a cloud 8 feet wide by 20 feet long ... they used a SINGLE slug, long and narrow (& wrapped in tape, too) so that its narrow end (about a half square foot) hits the RCC with hundreds of times the IMPACT PER AREA that it should.
    #2. They used a compressed air gun that gave a uniform, continuous accelleration -- in contrast the REAL foam is WHACKED by a 1550 mph Turbulent Wind (the Orbiter and the ET are only 3 feet apart throughout the foam's 60 foot journey) -- it must be like being hit by a dozen Force 10 tornados.

     You see, the whole point of the Foam is that if NASA leaves it off, they get ICE: and ICE may act much like this phony artificial "slug" -- stay in one piece, and hit like a spear on the pointy end (remember Icicles?).
     They never show the slightest reason why the Foam would act differently from its designed role (which is: TO BREAK UP).  Every Other flight, theory, model, test, and even camera pictures ... show that it would and DID break up.  The phony "controversy" over the foam's speed is just Misdirection.  
    
    Yet even THIS WAS NOT ENOUGH.
    The impacts still made only hairline cracks.
 
    #3. They used a nearly doubled impact angle to break through: Columbia's accellerometers measured an impact equivalent to 1.5 pounds at 16 degrees but to break the RCC panel they up'd it to a 26-or-30 degree angle(respectively "incident" and "clock" angles: the panel is rapidly curving at that point, what they mean is unclear)
     ... what was their excuse?

    They say the FOAM rotated -- like a rigid bar -- in a 1550 mph wind -- and the rotation ADDED to the impact.
    Now think: at their 18 rpm the 0.17 second trip saw 3 complete rotations -- one end of this 22 inch bar is moving with the wind, but the other is moving AGAINST the wind -- really !
    It HAS TO BREAK !!!!
    Even steel would probably bend.
    The fact is,
 A) we have never seen more than coin sized pieces
 B) the piece immediately behind the CAIB hole -- carrier panel #8 -- WAS FOUND -- and found: "NEARLY PRISTINE"
 C) If the hole is on the underside of #8, why are top pieces more likely to be missing and generally Much more badly damaged (e.g. the two charred remnants of the UPPER Carrier panel #8)?
 D) The wires die Top Down, not bottom up (oh excuse me I have already been critisized elsewhere on this: they did not say it that way: the CAIB reports says: in sequence "vertically toward the underside" -- not "Top Down" -- like as if that is different).
 E) Although most of the lower half of RCC Panel #8 is missing, like with RCC #9 the edges are mostly present and are ablated only facing the #8/#9 seam.  All the edges facing the supposed hole are broken, not ablated.
 F) We already lost a t-seal on an Atlantis flight, so we know the gap between #8 and #9 -- obviously the ONLY hot air entrance -- must have been PULLED APART SEVERAL INCHES.
 As only the usual strains are present, the wing must have already weak from damage recieved weeks before in the ascent, probably associated with and centering on the "elevon actuator" hole (the near twin of Challenger's Aileron hole) -- which hole the CAIB refuses to mention, and always Obscures, in detailed diagrams of the pieces (with the NASA Logo, or "whiting out" most of the top view).
   As you may be able to tell, I have been "mining" the CAIB report's Appendixes for details ... did you know there is an EXTRA "first" sensor to show problems (that the CAIB supressed)?-- along the line of where the wing broke off, it is the rearmost strain guage, reacting 10 seconds before its counterpart on the leading edge.  Boeing's initial judgement was overruled.
   Note, the line the wing broke off on, was heavily instrumented.
   ... that both ends of this string would go, with No changes in the middle dozen strain guages, and well before ANY temperature guages show changes ... The politicians HAD to supress the rear strain guage reading: it makes too clear a pattern.

RE: Shuttle Disaster

I like CusterWilson's manner of engineering investigation.

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