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Post by gillianren on May 28, 2007 22:35:48 GMT -4
It's a daunting amount of information, I know. But any question you have can be answered by someone around here (seldom me). Often, it's a lot easier an explanation than you would have realized.
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Post by PhantomWolf on May 28, 2007 23:42:06 GMT -4
Every Apollo flight except maybe for Apollo 17 underwent some sort of failure that required the pilots to improvise in some way or another.
I believe that 17's major inflight failure was that one of the three docking clamps failed to engage and they had to snap it into place manually. Not a particularly serious sounding problem, but they had to have tunnel open while doing it, and if they'd accidently caused a leak....
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Post by apollo13 on May 29, 2007 0:16:50 GMT -4
What happens if they caused a leak?
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Post by svector on May 29, 2007 0:32:32 GMT -4
The roll trim started to get wonky on the way home, and I figured out it was because one wing tank was being emptied faster than the other. Matt switched the fuel system from BOTH to LEFT in order to pull fuel from the left tank only and even out the weight. Within seconds the engine started to sputter and lose power. Not what you want to hear at 7,000 feet. My situation wasn't quite as severe, but as a young wannabe pilot, it got my attention. I was flying with my dad to his ranch about 150 miles north of where we lived. This was back in the early 80's in his Cessna 177 Cardinal. (I always loved that plane. Very sleek and sporty) I remember he had commented that the plane seemed to be using fuel more rapidly than usual. About halfway there, I happened to look back behind the right wing, and noticed a fine mist coming off the trailing edge. I mentioned it to him and he immediately knew what happened. He hadn't completely secured the filler cap when he gassed up, and the low pressure area on top of the wing was siphoning fuel out of the tank. He found a tiny little airfield that didn't even have a tower, and we landed. The tank by then was nearly dry, so he topped it off, took extra care to make sure the cap was secure, and off we went! Not as exciting as your story, but pretty cool to recount to my buddies in school the following week.
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Post by gillianren on May 29, 2007 0:43:28 GMT -4
What happens if they caused a leak? Well, leaks would let the air out, if I understand the situation. Letting the air out is a bad thing, as I'm sure you can imagine.
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Post by PhantomWolf on May 29, 2007 0:49:45 GMT -4
Letting the air out is a bad thingOnly if you can't breathe in a vaccum.
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Post by Obviousman on May 29, 2007 3:45:51 GMT -4
Late entry into the thread, so apologies. Some of my comments will refer to earlier posts. Apollo 13, 1. The most important things with regard to this subject are to examine all the evidence (from both sides), test the evidence where possible, and consult experts in areas where you do not have expertise. A lot of the photographic claims can be tested yourself by setting similar conditions. If someone says that a certain photograph is impossible, see if you can recreate the same thing yourself. If someone says that a certain scene should not happen, try to reproduce it yourself and see what happens. You can use what people - from both sides - tell you as a guide, but check what they tell you is actually correct. In some cases, you might not be able to do this (could the computers do what was claimed, is radiation too dangerous). In those cases, ask people who have expertise in that field about what is being claimed. Then seek out another expert, and ask the same thing. Perhaps even another expert. When most (if not all) experts agree on something, you can be reasonably assured that it is correct to the best of our knowledge. 2. Always check what people tell you is correct. Similar to 1 above, but check that what they say ("They went to Point A, stayed for 20 minutes, then went to Point B") is accurate. Sometimes people leave out important details, or get the details totally wrong (They went to Point A, stayed for 5 minutes, then went to Point D"). 3. Jays comments about the LLTV / LLRV are quite correct. It could have been made better, but 'better' is often the enemy of 'good'. The effort & time to do something perfectly often is counterproductive to being able to do something reasonably well. The astronauts who flew the LLRV / LLTV thought it was a nasty piece of work - but all said that it honed skills, prepared them for a lunar landing, and strongly recommended that other LM crews train with it. 4. Switches. Yep, things are sometimes complicated. Compare the cockpit of an early C-130 Hercules to a C-130J Herc: 5. Jay - yep, the first things taught to me: Aviate, Navigate, Communicate. (Fly the plane, make sure you know where you are & you are safe, then tell others - ATC - what your problems are) 6. I have great respect for Chuck Yeager, but his participation in the CHALLENGER investigation is over-rated in that post. He apparently did not attend any of the board fact-finding tours, meeting, or discussions; he only signed the final report (according to Neil Armstrong & others on the board). He's pretty correct with the assessment, but I was disappointed at his action with respect to the investigation.
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Post by Count Zero on May 29, 2007 4:35:53 GMT -4
I have great respect for Chuck Yeager, but his participation in the CHALLENGER investigation is over-rated in that post.
Read it again. I said three things about him, vis-a-vis the board: 1.) He was selected for the board. B.) He made a recommendation. III.) He was disgusted at the action NASA actually took.
Which one of these points is over-rated?
In truth, I agree that he was not a team-player, let alone a major participant in the board, but that is nowhere near the point that I was actually making, which was to give a relevant example of the philosophy Jay was talking about.
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Post by Obviousman on May 29, 2007 5:28:46 GMT -4
Not wishing to get into an arguement about this, but did he actually make that recommendation?
I don't know, but my understanding is he did not actually make any recommendation, he simply endorsed what the board said.
I am more than willing to be corrected on that if I am wrong, because as I said I have great respect for GEN Yeager and his achievements. My impression is that the CHALLENGER board was not one of his finest hours.
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Post by Count Zero on May 29, 2007 6:27:39 GMT -4
Perhaps I am not making myself clear. Twice now you have declared your "respect" for General Yeager and in the very next sentence thrown him under the bus by dredging-up sordid details that are in no way relevant to the overall conversational point being made, nor to any particular part of my post.
This is not "respectful" by any definition of the word.
You could have simply asked for a clarification about the recommendation, and left it at that. The answer is that it was not an official part of the report (that I'm aware of), but rather what he said publically in interviews after the physical cause was identified.
As far as his degree of participation in the board (I carefully avoided even saying that he had sat on it), I will paraphrase the interview (please remember that I am going from memory about something that I read 20 years ago): Any investigation of this nature can be broken down into two parts: "What happened?" and "What do we do about it?" From his point of view, Yeager had little relevant technical knowledge to offer the board. Thus, he had nothing to contribute to the "what happened" part of the investigation. What he did have was his experience as a test pilot and a general officer in how to keep a program moving forward. He quickly realized that people were more interested in chest-beating, finger-pointing and "management culture" than they were in carrying on with what he perceived to be the mission. In his mind, then, no one was interested in what he had to contribute to the "what do we do about it" portion of the investigation. In the end, he simply deferred to those with expertise in rocket boosters and managing civilian space programs, and washed his hands of it.
Can we leave it at that?
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Post by Obviousman on May 29, 2007 8:04:15 GMT -4
Count Zero,
I do have respect for GEN Yeager. He has been a 'hero' of mine for quite some time.
He was appointed to the board but apparently (and again, if this is not correct I would like to be corrected) he did not participate in any of the activities of the board. He certainly had a lot to offer: a test pilot, a Commander of the Aerospace Research Pilots School, and involvement in many projects regarding aerospace.
This alone makes his endorsement of the board findings valid. I just was disappointed that he - for whatever reasons - did not participate more in the actual investigations.
If he felt that "no one was interested in what he had to contribute to the 'what do we do about it' portion of the investigation" then IMO he should have resigned from the investigation. The fact that he did not would indicate that whatever his role in the investigative or decision making processes of the board, he felt his opinion was worthwhile.
The fact that I feel he did not do justice to his limited participation of the board does not detract - overall - from his great achievements or from the validity of his endorsement of the board findings.
I see no need to overstate his role in the investigations.
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Post by Count Zero on May 29, 2007 8:44:32 GMT -4
I see no need to overstate his role in the investigations....Which is precisely why I did not overstate his role in the investigation. See reply #67. Perhaps I even agree with you about his attitude, but it is NOT relevant to the point that I was making. I submit that I could have pointed out that his recommendation was informal, but that would have been beside the point. The point (if we can ever come back to it) was that Jay talked about the trade-off between safety and timely usefulness, and I tied that into the discussion of test pilot mentality with an example. That is all. Next up: Evan hijacks a discussion of the Kennedy presidency with nitpicks about JFK's marital infidelity.
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Post by JayUtah on May 29, 2007 10:01:48 GMT -4
It [the LLTV] could have been made better, but 'better' is often the enemy of 'good'.
Specifically, changing the machine with the intent of improving it doesn't always result in improvement. It does result in change, though, and that can invalidate much of what you've learned from past experience about how the machine behaves. No one had previously built an LLTV, so no one could be sure how it would respond to different situations. After several dozen flights you build up an operational picture, but then if you change the ship materially, you go back to Square One.
You could fit the LLTV to have a completely independent attitude control system with its own independent fuel supply. That would prevent a similar problem to Armstrong's from resulting in the crashed vehicle.
But you would have to connect the auxiliary system somehow into the flight controls so that the pilot could switch his controls from one to the other. So if the primary went out, it would either switch over automatically based on the input of some sensor and the decision of some logic, or the pilot could switch it manually. In either case, the overall flight control system is made more complicated than it strictly needs to be. You have one set of controls controlling a combination of downstream machinery instead of a simple one-to-one correspondence. As one of Jay's Engineering Mantras goes: Problems collect were stuff connects. The more interactions you propose and the more tightly you make things interact, the more chances for things to go wrong. So what you have in that case is an overall less safe control system.
Attitude control systems fail in other ways too. Not firing when they're supposed to is one way. Firing when they're not supposed to is another way. If you have two attitude control systems, both must work perfectly in the don't-fire-unexpectedly mode in order for the vehicle to fly. Having two systems increases the chances that a solenoid valve will stick open, because there are now twice as many of them.
And if you have two independent systems, the cost and effort to maintain them doubles for each vehicle. When you double a mechanic's workload, you increase the chances that he'll hurry through and not do a good job.
But the sentiment is still appropriate. If a flying machine crashes, you have a clear motivation and duty to make flying it safer. But that doesn't automatically translate into changing the machine itself. So to ask "Shouldn't NASA have done something?" is quite appropriate. But to ask "Shouldn't NASA have fixed the LLTV?" is to suggest a solution that may not be the right one.
Sometimes jiggling the toilet handle works just fine, even when you know that it's also possible to fix the problem by replacing the flapper valve and its actuators.
4. Switches. Yep, things are sometimes complicated.
And that's what we call essential complexity. There's no way to make the solution simpler without ignoring parts of the problem.
Again, an aircraft cockpit will become familiar to you after you spend enough time in it. Most people are taken aback because they spend so little time in that environment; they never have the time for it to sink in. But imagine going to work every day for three months and sitting (well, standing) in the LM cockpit simulator. That would give you enough familiarity.
Plus, engineers and pilots respect each other. I've never been in a Herc's cockpit, but the photograph shows me a familiar layout. Right in front of each pilot is a collection of gauges called the Sacred Six: those essential displays that show the plane's aerodynamic condition. They're always arranged in a particular pattern that is familiar to pilots and minimizes the typical pilot's pattern of looking from one to the other. Climb into a Cessna and you'll see the same Sacred Six arranged in the same pattern.
The field of gauges down the center indicate engine performance. Again, they're arranged in a particular grid pattern. The horizontal dimension is the engine's location on the wings. The vertical dimension is an order establised by long tradition. Interaction experts call this the small multiples principle. The pilot doesn't study each gauge. Instead he glances at the pattern of needles and absorbs in that single glance the state of his powerplants.
Other controls have distinct locations or shapes born of long tradition. Even if you don't know where immediately to find something, you know that the handle for the flaps will look like a certain thing.
The Apollo spacecraft had to break those rules a bit because many of the roles of the spacecraft didn't fit cleanly into airplane cockpit ideas. You couldn't, for example, duplicate the controls on the left and right sides of the CM because there wasn't enough room. And not everyone was an expert in every operation. When Apollo 12 was struck by lighting during launch, the sensor electronics were damaged. There was a switch-in backup, but the astronauts weren't immediately sure where to find the switch that selected it.
5. Jay - yep, the first things taught to me: Aviate, Navigate, Communicate.
Or, as Douglas Adams further reduced it: Don't Panic.
A plane with a wonky powerplant is still flyable. And we were over an area of Utah with which we were both quite familiar. This was a flight we call the Hundred-Dollar Sandwich. After landing at Wendover AFB, it's a short walk to the local Subway restaurant. The original plan was to take aerial photos and let me practice landings, but the CAP was doing a sort of exercise out there.
But I digress. Yes -- first get and keep control of the airplane. Check. Then decide where you need to go and how you're going to get there. Check. Then have them roll the trucks.
(Fly the plane, make sure you know where you are & you are safe, then tell others - ATC - what your problems are)
I have great respect for Chuck Yeager...
As do I, and whether it's true what he said regarding Challenger, the sentiment is Yeagerlich enough -- sometimes the best solutions are the simplest and most straightforward. "Doctor, it hurts when I do this." "Then don't do that."
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Post by scooter on May 29, 2007 10:09:36 GMT -4
Had there been a leak in the Command Module (or Lunar Module for that matter) it would have shown up in the telemetry and on the gauges as a slightly higher oxygen flow supplying the spacecraft for pressurization. It may be heard by the crew as well as a hissing or whistling. Then it's a matter of finding it and determining how to seal it.
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Post by gwiz on May 29, 2007 10:58:05 GMT -4
Don't fly the shuttle in cold weather. Probably not sufficient, seeing the number of earlier Shuttle flight that showed evidence of minor leaks past the O-rings. If I'd had to pick one relatively simple fix, it would have been the joint heaters to keep the O-rings warm.
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