Step-by-Step: How Columbia's Wing Might have Failed and Why

space.com ^ | February 19, 2003 | Jim Banke

[snopercod]

I can vouch for Doug Kohl. He was a darned good Site Test Conductor in the OPF. Sharp guy.

[snopercod]

one more for your list

[snopercod]

Just wondering if the modifications to the leading edge done in Palmdale changed the bonding and grounding of the RCC panels in any way. If one panel wasn't bonded properly, it could blow off if the shuttle were hit by "lightning", IMHO.

[NormsRevenge]

Bump

[RandyRep]

Interesting list of potential causes. Not much new - we all speculated on most of these during the first week after the loss. The only thing "new" here is the electrodynamic theory - if a "lightning strike" or "static discharge" or something similar happened in the minutes before contact was lost, wouldn't the crew and NASA data have noticed it?

I am surprised that they have not mentioned doing fluid dynamics and thermal analysis studies of the wing structure with various levels of damage. They should be able to simulate different levels of damage - such as the inboard leading edge missing, RCC gap filler missing, a patch of underwing tiles missing, etc. There should be fluid dynamics models and thermal models available to do this - unless they let those folks go - they could contract it to commercial software houses pretty quickly if they don't have the expertise now.

I am also surprised that they haven't said if they are doing some damage tolerance analysis - impact studies for the tank insulation, ice breakoffs, etc on the wing. This is routinely done in the aircraft industry to identify damage from birds, debris, etc. Again, there are experts who can consult on this if NASA doesn't have the capability.

[Tallguy]

I am surprised that they have not mentioned doing fluid dynamics and thermal analysis studies of the wing structure with various levels of damage. They should be able to simulate different levels of damage - such as the inboard leading edge missing, RCC gap filler missing, a patch of underwing tiles missing, etc.

Frankly, my money is on a piece of orbital debris, but your testing proposal is interesting. Destructive testing of this type will probably not yield an "easy fix", so there will be powerful disincentives to that line of investigation. Absent a "fix", the only logical outcome would be grounding the remainder of the fleet, and given the existance of the ISS, that ain't gonna happen.

[snopercod]

All good comments.

The Columbia was engulfed in a big pink-orange fireball at the point of the alleged discharge, so I could see how they might not have noticed any kind of electric display back behind them on the wing.

But it seems like "the lights should have flickered" or something. But maybe not. The shuttle electrical systems are mostly 28VDC, with a few 120VAC/400HZ circuits for rotary equipment. All black boxes and other metal pieces are scrupulously bonded to the airframe and checked with a milliohm meter. I can't really remember the spec. but "2 milliohms" sticks in my mind...

If there were any kind of a "lightning strike", it would have passed through the tiles, blankets, fiberglass (or whatever) and passed through the aluminum structure underneath before exiting somewhere else.

I am assuming that the RCC leading edges are conductive, but really don't know for sure. Neither do I know if and how they are bonded. The gaps between the sections would be a bonding concern, I think, but not sure.

If you have ever read anything on lightning strikes on fiberglass aircraft, it's pretty scary.

[Publius6961]

I can vouch for Doug Kohl. He was a darned good Site Test Conductor in the OPF. Sharp guy.

Tribal knowledge is cute and impressive and all, but for the rest of us...

What is OPF? In plain English?

[neuron2]

Whol will "vouch" for you?

[snopercod]

Sorry. Speaking in acronyms is a religion in the space program. We even had acronyms for acronyms. I never did learn them all.

OPF = Orbiter Processing Facility, the three "hangars" where the shuttles are processed at Kennedy Space Center.

They are an engineering marvel in themselves. Climate controlled, with emergency ventilation in case of a hypergol spill. Everything was explosion proof. Access platforms to reach the required areas. Supplied with all kinds of gasses and fluids necessary for processing.

[snopercod]

Whol will "vouch" for you?

Whol will "spell" for you?

[brityank]

All right. All right! Just who passed on the FReeper work product to NASA? ;^)
Thanks for the ping.

... seems like "the lights should have flickered" or something.

I have been in a 707 when the wing got hit by a bolt; other than a sharp crack of sound and the cabin lights flickering, nothing else seemed to happen -- no dips, no jerks, no change in engine sounds. WRT the Columbia, we already know that it was inspected for corrosion on the last refit at Palmdale, but how intense is that when done at KSC from the prior flight? Corrosion can play real havoc with electrical/electronic grounding and often cannot be seen without disassembly and microscopic examination.

Static can also punch holes in things, and usually has a high voltage and low current. If the grounding were compromised by either corrosion or misalignment due to the foam strike, that anomaly described on the pics from California could be an important straw on the pile of coincidences.

Bump.

[XBob]

Thanks for the bump brityank.

Snopercod: you said
"If you have ever read anything on lightning strikes on fiberglass aircraft, it's pretty scary."

There is word going around about an ion-storm/solar flare, scheduled to reach the earth at approximately 9AMest, coincidental with the re-entry, and the colombia should have been just going from night to day (at that altitude) , and be getting the first rays of sunlight just west of California coast. And this time frame also correlates with the time of the strange supressed 'lightning' photo from the Nikon camera in California.

I see no reference to this from NASA. Is it possible that this may have had something to do with a potential 'lightning' strike?

I am pretty certain that the shuttle has pretty good lightning protection, and has been hit several times before, without damaging it enough to crash it. (LOL - I was going to say 'serious' damage, but who knows what that is anymore?)

[Budge]

All right! Just who passed on the FReeper work product to NASA? ;^)

Wasn't me, but I wish we had...that is, if they weren't monitoring FR in the first place. :)

[RandyRep]

My recollection is that sunrise on the ground in CA was between 6:30 and 7 AM PST on 1 Feb. At a 40 mile altitude, sunrise would have been only 10 to 15 minutes earlier. So it's well before sunrise, even at altitude.

Ionization of the atmosphere down to about 60 km altitude (35 miles) occurs at sunrise - it is what kills skywave medium wave radio signals. But I don't think that atmospheric ionization is the culprit. Likewise, if there were a solar flare at that time, the additional ionization is usually centered over the magnetic poles (aurora borealis) and not as far south as CA (I live in San Diego and have never seen the aurora here).

Concerning a "lightning strike" event - I'm pretty sure that the RCC tiles and the black wing tiles are not very electrically conductive. On aircraft, any composite material on potential strike surfaces (nacelles, nose cone, wing tips, etc) has metal fiber screens embedded and jumpers to metallic structure to minimize lightning strike damage. My guess (and only a guess, as I'm not an expert in any of this) is that the lightning protection in the orbiter were designed for the "aerodynamic" portion of the glide and landing, not the "heating" portion of re-entry.

[XBob]

15- "My recollection is that sunrise on the ground in CA was between 6:30 and 7 AM PST on 1 Feb. At a 40 mile altitude, sunrise would have been only 10 to 15 minutes earlier. So it's well before sunrise, even at altitude. "

The kids north of flagstaff video films shows sunrise on the ground at 06:55:53, and their video is lost in the light. The sun shines on the bird, quite some time before you can view any light in the sky on the ground.

It may be that some of the suddenly 'glowing' photos actually may be the first light of dawn striking the bird, before any sunlight is visible from the ground.

The remainder of your post needs a more qualified answer than I am able to provide.

[XBob]

I was in a 707 hit by lightning also, and it blew off the nose radome, and as a minuimum blew out the intercom, as the captain couldn't tell us what was going on, without coming back and telling us by voice.

We had to do an emergency landing.

[XBob]

15 - SC, perhaps you can help randy on this.

[bonesmccoy]

wow.
that's some event!

Thanks for the ping.

Looks like my friend is still searching for a link to Palmdale.

I enjoy hunting and fishing too.

However, it is more enjoyable when you actually have some game to bag or a fish to fry.

Palmdale OMDP is worth a look. But by my guess, it will be hunting in a blind with no geese. There's no work being done there anyway. Even if you did find a problem, there's no operation there to hold accountable.

Hold it!

I guess that could be a reason for the USA/KSC people to point guns to California and aim.

"It's not my fault" could be the chorus.

[XBob]

the culture of blame