Virgin Galactic
Discussion
Eric Mc said:
The feathering system lock was "unlocked" too early. This allowed the tail section to move into the feathered position whilst the aircraft was accelerating through the Max Q - the period of maximum dynamic pressure on the vehicle. This was enough to cause structural break up and loss of the vehicle.
Really? the NTSB is quoted as saying: "The vehicle was not traveling fast enough for aerodynamic forces to keep the so-called “feather” pinned in place, as designs called for."
Also isn't it best to await the full investigation report ?
MartG said:
New project announced today
http://www.virgin.com/richard-branson/creating-the...
Using LauncherOne http://www.virgingalactic.com/satellite-launch/
Well this will really piss on his chipshttp://www.virgin.com/richard-branson/creating-the...
Using LauncherOne http://www.virgingalactic.com/satellite-launch/
http://mobile.businessweek.com/articles/2015-01-17...
Eric Mc said:
Of course it's always best to wait.
But this is a discussion forum where people discuss things - so I was discussing.
If you don't want to join in the discussion, don't.
It read as a statement of truth rather than a discussion point, of course there will be some semblance of truth as its is what we have been told by the NTSB but clearly the same team said that the craft “wasn't fast enough for aerodynamic forces to keep the so-called “feather” pinned in place, as designs called for.”But this is a discussion forum where people discuss things - so I was discussing.
If you don't want to join in the discussion, don't.
Now compare that statement to yours which said:
This allowed the tail section to move into the feathered position whilst the aircraft was accelerating through the Max Q - the period of maximum dynamic pressure on the vehicle. This was enough to cause structural break up and loss of the vehicle.
Now put those two statements together and you can start having a discussion, some simple questions….. (which probably require more complex answers)
1) What is Max Q and how does that relate being “fast enough” or is it a red herring
2) What speed is fast enough?
3) How far apart from the actual speed to the fast enough speed
4) The aerodynamics mentioned will probably be affected by altitude, therefore the “fast enough speed” will change at differing altitude
5) is it possible to design out the need to utilise the aerodynamic forces to keep the ‘feather’ pinned in place as mentioned
Blimey this might start a discussion
All very good points.
The issue that concerned me seemed to be the very narrow speed window within which it was unsafe to unlock the feathers and then the point where they deemed it prudent to unlock them.
That could be a design fault.
And testing is what highlights where design faults might lie.
The issue that concerned me seemed to be the very narrow speed window within which it was unsafe to unlock the feathers and then the point where they deemed it prudent to unlock them.
That could be a design fault.
And testing is what highlights where design faults might lie.
Toaster said:
Eric Mc said:
The feathering system lock was "unlocked" too early. This allowed the tail section to move into the feathered position whilst the aircraft was accelerating through the Max Q - the period of maximum dynamic pressure on the vehicle. This was enough to cause structural break up and loss of the vehicle.
Really? the NTSB is quoted as saying: "The vehicle was not traveling fast enough for aerodynamic forces to keep the so-called “feather” pinned in place, as designs called for."
Also isn't it best to await the full investigation report ?
ie, they didn't say "lever moved too soon" deliberately..........
So Eric you said
"The issue that concerned me seemed to be the very narrow speed window within which it was unsafe to unlock the feathers and then the point where they deemed it prudent to unlock them".
!) what is the narrow speed window? I do not have that information
That could be a design fault.
And testing is what highlights where design faults might lie.
2) if its known that there is an issue in being "fast enough" then its design intent not a fault, so the question is what is going to stop 'it' happening again and what other scenarios could place the crew and passengers at risk as this would appear to be a known fault.
Don't forget Concorde had its weakness's and it wasn't until the fuel tanks were punctured that it was said "they wouldn't design it like that now"
So given the "knowns" what will change and if nothing the risk has not been removed.
"The issue that concerned me seemed to be the very narrow speed window within which it was unsafe to unlock the feathers and then the point where they deemed it prudent to unlock them".
!) what is the narrow speed window? I do not have that information
That could be a design fault.
And testing is what highlights where design faults might lie.
2) if its known that there is an issue in being "fast enough" then its design intent not a fault, so the question is what is going to stop 'it' happening again and what other scenarios could place the crew and passengers at risk as this would appear to be a known fault.
Don't forget Concorde had its weakness's and it wasn't until the fuel tanks were punctured that it was said "they wouldn't design it like that now"
So given the "knowns" what will change and if nothing the risk has not been removed.
No machines are perfect and sometimes all one can do is work around those imperfections as best you can. The Shuttle is a classic example of a very imperfect vehicle. They got it to work - not as well as they would have liked - but work none the less.
Sometimes it is only through testing that some of these issues come to the fore.
Sometimes it is only through testing that some of these issues come to the fore.
Eric Mc said:
No machines are perfect and sometimes all one can do is work around those imperfections as best you can. The Shuttle is a classic example of a very imperfect vehicle. They got it to work - not as well as they would have liked - but work none the less.
Sometimes it is only through testing that some of these issues come to the fore.
But that is not a good enough approach when dealing with peoples lives (civilians we are not talking test pilots or other high risk takers) IMHO, so meantime between failure, system unavailability etc will all need to be factored in.....so what is the probability of a system failure of the next vehicle? ( I mean statistically here as this is supposed to be a science thread) are we talking about 99.999 reliability? 99.0 or more likely much less 75-80% Sometimes it is only through testing that some of these issues come to the fore.
All aircraft have to be tested by test pilots before passengers can be carried. There are lots of examples of early versions of airliners or civil aircraft having problems that were sorted out in test before entering airline service.
Are you saying because there has been a problem they should give up?
Are you saying because there has been a problem they should give up?
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