Skip to comments.Actual text of that Nasa Email
Posted on 02/13/2003 7:59:02 AM PST by dark_lord
The text of an e-mail from NASA safety engineer Robert H. Daugherty to officials at Johnson Space Center two days before the Columbia disaster:
Excerpted stuff here...
The following are scenarios that might be possible ... and since there are so many of them, these are offered just to make sure that some things don't slip thru the cracks. ... I suspect many or all of these have been gone over by you guys already:
1. People talk about landing with two flat tires. ... I did too until this came up. If both tires blew up in the wheel well (not talking thermal fuse and venting but explosive decomp due to tire and/or wheel failure) the overpressure in the wheel well will be in the 40+ psi range. The resulting loads on the gear door (a quarter million lbs) would almost certainly blow the door off the hinges or at least send it out into the slip stream ... catastrophic. Even if you could survive the heating, would the gear now deploy? And/or also, could you even reach the runway with this kind of drag?
2. The explosive bungies ... what might be the possibility of these firing due to excessive heating? If they fired, would they send the gear door and/or the gear into the slipstream?
3. What might excessive heating do to all kinds of other hardware in the wheel well ... the hydraulic fluid, uplocks, etc? Are there vulnerable hardware items that might prevent deployment?
4. If the gear didn't deploy (and you would have to consider this before making the commitment to gear deploy on final) what would happen control-wise if the other gear is down and one is up? (I think Howard Law and his community will tell you you're finished)
5. Do you belly land? Without any other planning you will have already committed to KSC [Kennedy Space Center]. And what will happen during derotation in a gear up landing (trying to stay away from an asymmetric gear situation for example) since you will be hitting the aft and body flap and wings and pitching down extremely fast a la the old X-15 landings? My guess is you would have an extremely large vertical decel situation up in the nose for the crew. While directional control would be afforded in some part by the drag chute ... do you want to count on that to keep you out of the moat?
6. If a belly landing is unacceptable, ditching/bailout might be next on the list. Not a good day.
7. Assuming you can get to the runway with the gear deployed but with two flat tires, can the commander control the vehicle both in pitch and lateral directions? One concern is excessive drag (0.2 g's) during TD [touchdown] throughout the entire saddle region making the derotation uncontrollable due to saturated elevons ... resulting in nose gear failure? The addition of crosswinds would make lateral control a tough thing too. Simulating this, because it is so ridiculously easy to do (sims going on this very minute at AMES with load-persistence) seems like a real no-brainer.
Excerpted more stuff here...
Best Regards, Bob
(Excerpt) Read more at chicagotribune.com ...
I betcha there were 100,000 such emails on as many topics, covering every possible failure mode of the Shuttle.
And I love NASA's euphamisms for catastrophic failures: "We had a bad day" and "not a good day"...
I'd like to see that. You also might check CNN's website and see if they have the animation they showed this morning that was provided by some private company...
The animators took the various GPS coordinates where debris was found and made a visual depiction of how the breakup would look to an observer facing westward at approximately the alt. the Columbia was. It was pretty stunning stuff. Showed how pieces would fall off, then deccelerate from the drag, then fall earthward.
Really? Is there a link somewhere to this story?
The gear is lowered hydraulically after the gear-down command. If there is a failure in the hydraulics then the gear is blown down.
"For deployment of the landing gear, the uplock hook for each gear is activated by the flight crew initiating a gear-down command. The uplock hook is hydraulically unlocked by hydraulic system 1 pressure applied to release it from the roller on the strut to allow the gear, assisted by springs and hydraulic actuators, to rotate down and aft. Mechanical linkage released by each gear actuates the respective doors to the open position. The landing gear reach the full-down and extended position within 10 seconds and are locked in the down position by spring-loaded downlock bungees. If hydraulic system 1 pressure is not available to release the uplock hook, a pyrotechnic initiator at each landing gear uplock hook automatically releases the uplock hook on each gear one second after the flight crew has commanded gear down."
Just log in as ANNOYING, password ANNOYING. Works on the Trib website and many others, too.
Or, I guess, if the pyrotechnic initiator is prematurely set-off.....yikes.
Odd that doesn't show up in the coversation between NASA and the shuttle. Is there a delay/edit on that audio stream?