SpaceX Tuesday...
Discussion
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MartG said:
Chester35 said:
I find it interesting that they wanted to get an abort with conditions perfect so kept putting it off. The full test of an abort probably needs to be done at the worst scenario ever, which means doing it in conditions you would not normally launch at.
That's a rather a crossing all the t's and I's to the nth degree though...
They need to do the test in good conditions to maximise the amount of data they can get from it e.g. high quality video from ground camerasThat's a rather a crossing all the t's and I's to the nth degree though...
Einion Yrth said:
MartG said:
Chester35 said:
I find it interesting that they wanted to get an abort with conditions perfect so kept putting it off. The full test of an abort probably needs to be done at the worst scenario ever, which means doing it in conditions you would not normally launch at.
That's a rather a crossing all the t's and I's to the nth degree though...
They need to do the test in good conditions to maximise the amount of data they can get from it e.g. high quality video from ground camerasThat's a rather a crossing all the t's and I's to the nth degree though...
I was watching the EveryDayAstronaught video today and he showed nothing of it apart from him and his fellow video people watching it and dancing up and down. You can pay for a comment on the channel and at the point of launch it seemed to go up to $100 just to post a comment which he would not see
then settled down to the normal $10 or $5 etc
He's really milking the audience. An Everyday millenial US salesman ....
As I mentioned earlier, in the case of a catastrophic failure, it's highly likely you will lose much of that telemetry - especially from the moment of destruction. Remember the Mission Control call-out when Challenger was destroyed "Flight, we have negative downlink". It meant they received absolutely no telemetry from the moment the vehicle broke up. The only data they could see from that moment was the TV cameras were showing.
When testing, you optomise as much as you can PRECISELY because it's a test. Once you get used to a system, you can relax some of the tight launch constraints. But even that can cause problems. Apollo 12 was struck by lightning because it took off in less than ideal weather conditions.
Challenger was destroyed because it took off in temperatures that had originally been set as a "red line" for launch.
When testing, you optomise as much as you can PRECISELY because it's a test. Once you get used to a system, you can relax some of the tight launch constraints. But even that can cause problems. Apollo 12 was struck by lightning because it took off in less than ideal weather conditions.
Challenger was destroyed because it took off in temperatures that had originally been set as a "red line" for launch.
Gandahar said:
Poppycock, people are always not scrubbing launches just like in Feb 1986 just due to ;pressures. A test on a failure should be on the worst possible conditions not the best.
I was watching the EveryDayAstronaught video today and he showed nothing of it apart from him and his fellow video people watching it and dancing up and down. You can pay for a comment on the channel and at the point of launch it seemed to go up to $100 just to post a comment which he would not see
then settled down to the normal $10 or $5 etc
He's really milking the audience. An Everyday millenial US salesman ....
No - if you have a failure on a test, you want to be sure that the failure was something that can be attributed to a technical or operational flaw - not due to some outside influence, like rain, cold weather, lightning or wind shear.I was watching the EveryDayAstronaught video today and he showed nothing of it apart from him and his fellow video people watching it and dancing up and down. You can pay for a comment on the channel and at the point of launch it seemed to go up to $100 just to post a comment which he would not see
then settled down to the normal $10 or $5 etc
He's really milking the audience. An Everyday millenial US salesman ....
Rockets are fragile beasts. You need to give yourself every opportunity to see, know and understand what has happened if there is a failure. Adding unpredictable variables like the weather is just dumb - and they don't do it.
This test needed to be observed visually ESPECIALLY if the test was a failure as the visual record might be the only record available after the moment of failure.
The Challenger accident (which was in January 1986, not February) was not a test flight. It was "operational". Indeed, it was the immense pressure NASA felt to show how "operational" the Shuttle system was that encouraged them to take a chance with the weather - with tragic consequences.
Edited by Eric Mc on Sunday 19th January 16:10
Eric Mc said:
As I mentioned earlier, in the case of a catastrophic failure, it's highly likely you will lose much of that telemetry - especially from the moment of destruction. Remember the Mission Control call-out when Challenger was destroyed "Flight, we have negative downlink". It meant they received absolutely no telemetry from the moment the vehicle broke up. The only data they could see from that moment was the TV cameras were showing.
When testing, you optomise as much as you can PRECISELY because it's a test. Once you get used to a system, you can relax some of the tight launch constraints. But even that can cause problems. Apollo 12 was struck by lightning because it took off in less than ideal weather conditions.
Challenger was destroyed because it took off in temperatures that had originally been set as a "red line" for launch.
In summary testing in ideal conditions has a bad past record when it comes to real world stuff. And we still do it ....When testing, you optomise as much as you can PRECISELY because it's a test. Once you get used to a system, you can relax some of the tight launch constraints. But even that can cause problems. Apollo 12 was struck by lightning because it took off in less than ideal weather conditions.
Challenger was destroyed because it took off in temperatures that had originally been set as a "red line" for launch.
Having said that Boing failed their rendesvous test with the ISS and they seem still good to go. Go figure. I can't argue against perfected testing when another company doesn't even get perfected testing right and is still good to go....
Depends on the nature of the failure.
Look at Apollo 8. The previous launch of the Saturn V (Apollo 6) had suffered a number of serious failures although the vehicle was not lost.
If the technicians feel they know and understand what happened and they have devised a "fix" to make sure it won't happen again, then it might be OK to go ahead without repeating that particular test flight again.
Look at Apollo 8. The previous launch of the Saturn V (Apollo 6) had suffered a number of serious failures although the vehicle was not lost.
If the technicians feel they know and understand what happened and they have devised a "fix" to make sure it won't happen again, then it might be OK to go ahead without repeating that particular test flight again.
Eric Mc said:
Gandahar said:
Poppycock, people are always not scrubbing launches just like in Feb 1986 just due to ;pressures. A test on a failure should be on the worst possible conditions not the best.
I was watching the EveryDayAstronaught video today and he showed nothing of it apart from him and his fellow video people watching it and dancing up and down. You can pay for a comment on the channel and at the point of launch it seemed to go up to $100 just to post a comment which he would not see
then settled down to the normal $10 or $5 etc
He's really milking the audience. An Everyday millenial US salesman ....
No - if you have a failure on a test, you want to be sure that the failure was something that can be attributed to a technical or operational flaw - not due to some outside influence, like rain, cold weather, lightning or wind shear.I was watching the EveryDayAstronaught video today and he showed nothing of it apart from him and his fellow video people watching it and dancing up and down. You can pay for a comment on the channel and at the point of launch it seemed to go up to $100 just to post a comment which he would not see
then settled down to the normal $10 or $5 etc
He's really milking the audience. An Everyday millenial US salesman ....
Rockets are fragile beasts. You need to give yourself every opportunity to see, know and understand what has happened if there is a failure. Adding unpredictable variables like the weather is just dumb - and they don't do it.
This test needed to be observed visually ESPECIALLY if the test was a failure as the visual record might be the only record available after the moment of failure.
The Challenger accident (which was in January 1986, not February) was not a test flight. It was "operational". Indeed, it was the immense pressure NASA felt to show how "operational" the Shuttle system was that encouraged them to take a chance with the weather - with tragic consequences.
Edited by Eric Mc on Sunday 19th January 16:10
That;'s my whole point. They are testing for a subset,
When it finally launches you will have rain and cold weather etc.
They ain't going be testing for that are they ??
Gandahar said:
"No - if you have a failure on a test, you want to be sure that the failure was something that can be attributed to a technical or operational flaw - not due to some outside influence, like rain, cold weather, lightning or wind shear."
That;'s my whole point. They are testing for a subset,
When it finally launches you will have rain and cold weather etc.
They ain't going be testing for that are they ??
Operational launches do not take place under those conditions, so why test in them ?That;'s my whole point. They are testing for a subset,
When it finally launches you will have rain and cold weather etc.
They ain't going be testing for that are they ??
If they had to test for every weather condition, the rocket might never become operational. This was a test of an escape system to make sure it worked. They needed to have good weather so any failure could not be caused by the weather and they needed to see what was going on. They also needed a good sea state so they could recover the capsule safely.They postponed it for 24 hours to get the conditions they wanted.
They know what they are doing. People have been testing large rockets and their related systems for almost 80 years.
They know what they are doing. People have been testing large rockets and their related systems for almost 80 years.
Another angle capturing the rocket's disintegration and the capsule streaking safely away from it:
Post test press conference:
https://www.youtube.com/watch?v=21X5lGlDOfg
Post test press conference:
https://www.youtube.com/watch?v=21X5lGlDOfg
Gandahar said:
"No - if you have a failure on a test, you want to be sure that the failure was something that can be attributed to a technical or operational flaw - not due to some outside influence, like rain, cold weather, lightning or wind shear."
That;'s my whole point. They are testing for a subset,
When it finally launches you will have rain and cold weather etc.
They ain't going be testing for that are they ??
Pretty sure they don't launch in the rain since the lightning strike issue on Apollo 12. That;'s my whole point. They are testing for a subset,
When it finally launches you will have rain and cold weather etc.
They ain't going be testing for that are they ??
You can never test for every single possible condition, you test for a set of conditions you have modelled and compare your results to that model. That's what they have done today. If they had launched into conditions that were worse than the model, they would not have a true comparison. And if they had modelled really poor conditions they would have ended up with a more complex (heavy, whatever) capsule to cope with those conditions plus safety factor plus the factor for unknown errors in the model.
They now have a baseline for the conditions where the abort system [i]will/[i] work and can set acceptable launch parameters based on that. Those parameters may mean wider or narrower conditions are allowed based on examination of the results and comparison with the model, plus as they gain flight experience and compare the actual wear and margins on the aircraft they can revise them again. Blowing up several rockets to test all the different situations would be expensive and unnecessary - they have proven that in today's conditions it works.
On light aircraft there is a (slightly apocryphal) story that the "crosswind limit" in the pilot's handbook was originally just the maximum crosswind on the day of the test. Anecdotally a lot of aircraft can land in far worse crosswinds but the manufacturers did their calculations/tests and that was what went in the book.
Also, let's consider the abort tests that Boeing has done. Oh yes, none. It's all been signed off on the simulations.
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