Observation on TPS damage on Orbiter

NASA photos | 2-3-03 | BoneMccoy

[freepersup]

I never thought about a jettisonable protective design ? I would like to see the NASA engineers work out some of our ideas / suggestions into an operable mode (in theory). Put the nation's most powerful computers to work at once on such scenarios. Use our brightest minds to write the programming.

I am thinking along the lines of a more powerful lift capability for a multitude of benefits and reasons. The ability to protect the tiles with plating would be a fringe benefit, but not the primary reason for a bigger rocket.

[freepersup]

[spunkets]

The glove.

[spunkets]

The center image there was taken from below and off to the right side some ways. So the pic wouldn't be symmetrical. Also is image is created by the light from the plasma generated by the orbiter crusing through the atmosphere and also the visible radiation from high temp surfaces. That's why the outline of the ship isn't the same as it's seen standing still.

What seems to be sticking out from the front, inboard side of the left wing is light generated from very high temps. The carbon is probably burning there. It's light from very hot gasses. That's also what the trail is behind the left wing. The whole backside also has hot plasma trailing off the back, that's why the outline of the back side doesn't look like the still image.

[John Jamieson]

NASA says the foam from the ET is probably not enough to cause enough damage to the TPS system to do this, and yet they're are doing lots of work with the ET team members. I'm going to accept their foam theory for a while and look at other ET related causes.

The only thing I can think of is the orbiter and ET collided at ET seperation much like that Progress hit the Russia Space Station a few years ago. That ET front attach point could have done a lot of damage to the leading edge of the wing. The Astonauts would know, but would they tell the world, or even JSC that they had screwed up?

I'll try to find more info on ET sep.

[Thud]

Xbob, you said in your No. 523 that you had observed an elvon burn-through on a landed orbiter which had come within 1-3 second of severing the elvon.

Question: would that same burn-through have brought down that orbiter if the orbiter had the re-entry profile of Columbia?

I.e., is fatal elvon burn-through a more frequent potential occurance than discussed so far? Are there simpler explanations for Columbia's loss than the foam strike?

[John Jamieson]

“Just before orbiter/ET separation, the reaction control system is inhibited. It is re-enabled immediately after ET separation to an inertial attitude hold. The transition DAP then commands the RCS to thrust the four forward and six aft negative RCS jets for a minus Z translation to achieve a 4-foot-per-second separation vertically, ensuring orbiter clearance from the arc of the rotating tank. When the required separation is achieved, the thrusting commands to the negative RCS jets are removed. The orbiter continues to coast away from the tank in the inertial attitude hold mode, gaining additional vertical clearance.”

“Depending on mission requirements, the crew may be required to translate in the plus X direction, using the translational hand controller for 11 seconds, to allow the external tank camera to photograph the tank.”

[freepersup]

Are there simpler explanations for Columbia's loss than the foam strike?

The debris strike is a pretty darn simple explanation. Lot's of aircraft over history have been brought down by 'object' strikes. I know of a skydiver striking a four engine aircraft while in freefall ! The aircraft, in this case of an object strike, survived the mid air collision. The jumper didn't.

This near burn through of the elevon had a root cause of what ? Debris strike ? Too hot of an approach (for lack of a better description) ?

You ask a good question about the elevon burn through and it's angle of attack (?) in presentation to the Earth's atmosphere. How much of a 'window' does the shuttle have for adjusting this re-entry flight path ? Does the shuttle's design, by virtue of primarily shielding the underside with protective tiles, limit this window due to severe restrictions on flight attitude (angle of attack) Am I confusing angle of attack with glideslope ?

[Eastbound]

Scale pix:

[Thud]

What I meant by "simpler explanation" was that, if there was an almost fatal elvon burn-through in a prior mission which did not have a foam strike, and that mission's re-entry profile was significantly less hazardous than Columbia's, perhaps the same cause of the elvon burn-through which was almost fatal earlier was fatal for Columbia. I.e., that the foam strike was either not fatal here or, if I'm wrong,

there were multiple overlapping fatal failures for Columbia.

[freepersup]

Forgive my delivery as on second read I appear insolent. I did not mean to come across that way.

Your question was one that could be directed to all future shuttle re-entries. Houston do we have a problem ?

Regarding the re-entry profiles: The ship's underside has to be presented to the relative wind (pitch) in a narrow range that is limited by aerodynamic properties and by the necessity of a proper approach that utilizes the shielding correctly.

Granted- when the ship's nose is pitched down, it makes for a steeper approach, and when the ship's nose is pitched up, it makes for a shallower approach.

What constitutes a hazardous profile ? 'Too much', either side of the range ? Less weight = less speed = less heat vs more weight = more speed = more heat ?

If erroneous calculations put the shuttle over or under the re-entry profile, adjustments would have to be made. If a nose high attitude was assumed for longer than anticipated, thus exposing the elevons to a greater amount of heat than they were engineered for, a possible burn through might occur.

First I've heard of the elevon nearly burning through. Must have been a lot of paperwork exchanges going on.

[spunkets]

Well, I can't rule out the result of critical damage during the debris hit Here's why.

They were 81 secs into the flight. Although I don't know how high they actually were yet, they were at, and probably over 120000 ft. I didn't know before whether the debris was a frost buildup ,or foam, because I had a problem understanding why a chunk of closed-cell urethane foam(Celotex) would explode like that. At 120Kft, the pressure is very low, but the internal pressure of the foam is still 14.7psi. There's 20ft-lbs of internal E, so I can see how it might explode with some extra budge.

I had some velocity numbers before from the film. Considering the were around 2.6g acceleration and the uncertainty from those rough films, I have 317ft/sec (216mph) for the debris. It also has ~5rev/s angular velocity. NASA gave 2.67lbs for the block in a news conference(sig figs?..lol). I got around 8.3 slugs 1 atm. That converts to ~2.5lbs for the hight and acceleration of the ship in the video. That results in 4200ftlbs of kinetic E. That's roughly the muzzle v of a .340 Weatherby mag.

The angle of incidence for the hit is around ~3 degrees. That would give an energy applied in the normal direction of 220ft-lbs, about a 45 slug at 150yds and a shearing E of ~ 4000 ft-lbs. The rotation is counterclockwise if I remember right, that would greatly increase the normal force and E from the hit. I look at the angular part yet.

The tile is probably ~5" thick at that point on the wing(NASA). Having worked with low density ceramics, like this, I think the underlying silica would easily be crushed and damaged with a hit like this. The end result would be that a chunk would be completely loosened, or knocked out. There would then be a reletively deep, cuplike cavity. There would be little problem with the thermal insulation value 'till reentry, where a flow eddy would errode the pocket continuously and greatly increase the temps there, until it reached the Nomex and began the burn through. That's a process similer to how pools are formed in a trout stream, or how the bottemless pits in my valley are created by flash floods, that swallow the deer. lol. First a small pocket is formed an then an eddy comes and digs out the rest.

[freepersup]

# 602 appears oddly different in shape, however the distance to subject, extreme heat, and high speeds have distorted the images. The 3 image's shapes are relative to each other.

Thanks-

[XBob]

585-"That is a sizable chunck of carbon/carbon.

Don't you think that wing parts found in the Dallas/Ft. Worth area more than likely would be from the right wing? It would seem any left wing parts would be further west."

---

that chunk of carbon/carbon is probably from the leading edge of one of the wings. this is the heaviest, most solid, insulation, in the biggest pieces originally.

where parts would be found, I haven't got a clue, but I have heard that the heaviest parts generally have been found in Lousiana - a main engine or two, and a couple of other heavy things.

[small_l_libertarian]

Just looking at the diagrams of the shuttle ... should we be able to see the tail of the shuttle in the Air Force photo? I don't see a tail.

[Eastbound]

Your welcome. It looks like the #602 image was not photographed dead center. A few degrees to one side might account for the uneven fuselage line, and might also show a distortion in the left wing. Whatever, it still looks like the left wing is damaged.

[XBob]

589 - "THINK BIG- we have to think anyway. paraphrasing (I think) Donald Trump "

I agree, however, a bit differently.

With the Saturn We went to the moon on a 'conestoga wagon' pulled by giant oxen.

With the shuttle go to the space station in a 'horse and buggy'

It's time we spent our money and effort, inventing the 'internal combustion engine' and invent anti-gravity, instead of trying to make a better horse and buggy.

Chemical rocket travel, where you must lift all your fuel with you, out of the giant gravity well called earth, before you can even begin to travel, is just no way to travel in space in the long run.

Let's kick butt and invent a whole new method. What are we getting from the shuttle program now, a perfume from outer space (no joke - that is one of the experiments which was on the colombia)

The shuttle is a giant heap of probabilites of accidents waiting to happen.

[XBob]

590-"In my travels and career I have used a plasma cutter on numerous occasions. They cut metal faster than a oxy-acetylene torch. The plasma blows the hot debris out of the way and hungers for more. It is very fast once you get it going and cuts almost anything, especially stainless and aluminum alloys."

then you should realize just how quickly the loss of one tile, and consequential leaking in of the plasma, would destroy a critical part.

I just read the timeline again, and saw that almost the first sensors lost were the elevon control sensors. That stream coming off the rear could be the elevon/elevon control shaft burning through. (I need to try to correlate elevon control and rcs control bursts). There were only supposed to be two turns to scrub off speed, first a left, then a right.

[XBob]

592- "I agree with the first part of your secondary theory. IMO the tile-shedding began at the trailing edge. "

---

see #618

[Eastbound]

My guess would be that the surface area was too narrow to register, or the outline of the tail blended in to the shuttle because of the angle of view between the camera and the shuttle.