Acceptable foam loss?

Status
Not open for further replies.
R

radarredux

Guest
NASA has admitted that there will be foam loss from the ET in this shuttle launch. The concern is the size and number of pieces.<br /><br />Has NASA declared ahead of time what they would consider an acceptable or unacceptable size for a piece of shedding foam? For example, is 0.25 pounds or less acceptable, but anything over a 0.25 pounds indicates a failure of the design? (the number "0.25 pounds" is for illustration purposes only)<br /><br />Usually in an experiment you try to define acceptable values for a test <i>before</i> the data is collected and analyzed. Has NASA put a stake in the ground and said what is acceptable and what isn't?
 
Q

qso1

Guest
I'm pretty sure they have internally. They just haven't stated publically what it is...then again maybe not. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
P

propforce

Guest
Time the foam come off?<br /><br />What different would that make as the Shuttle is already in air? <div class="Discussion_UserSignature"> </div>
 
Q

qso1

Guest
The purpose of the foam is to keep chunks of ice from falling off the tank and striking the orbiter. Ice will still be present on the tank well into the ascent as we saw with the Columbia and one can see with old Saturn-V launch footage. Much ice coming off the vehicle from mostly stage 2 but IIRC, stage 1 as well. The foam had generally worked well until Columbia of course, and it worked after Columbia on the RTF. But imagine a bare tank. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
P

propforce

Guest
<font color="yellow">The purpose of the foam is to keep chunks of ice from falling off the tank and striking the orbiter.</font><br /><br />Yes I am aware of that. So I'd think one key criteria for "acceptable foam loss" should be depending on where it strikes the orbiter and to what extent of damage? <img src="/images/icons/smile.gif" /><br /><br /> <div class="Discussion_UserSignature"> </div>
 
P

propforce

Guest
<font color="yellow">The impact velocity is differrent. The higher you go the less drag thus the foam that comes off does not slow down as fast as it does at lower altitude. With no or little drag the vehicle acceleration determins the force of the impact. At lower altitude the foam rapidy slows down as soon as it comes off thus the impact velocity (force) is greater as the vehicle accelerates into the foam. </font><br /><br />Thanks. Good point too as vehicle flight velocity is much higher at a later time as well.<br /> <div class="Discussion_UserSignature"> </div>
 
A

askold

Guest
What do you mean by "acceptable"? If an unacceptably large piece of foam comes off (but doen't make a hole in the shuttle) - then what? They stop flying for another year, or what?
 
W

webtaz99

Guest
I have read that NASA did extensive testing concerning this. Even if they don't define it publicly or precisely, I think they have a good idea what will and will not damage the shuttles. <div class="Discussion_UserSignature"> </div>
 
R

radarredux

Guest
> <i><font color="yellow">However with little drag the foam does not slow down very much.</font>/i><br /><br />It sounds like there is an envelope. On one axis is the speed of the foam relative to the speed of the vehicle. On the other axis is the size of the piece of foam.<br /><br />The speed of the foam relative to the speed of the vehicle, is a function of the air speed of the vehicle and the air density.<br /><br />There is still an interesting issue: a large piece of foam falls off that but does not have a large amount of relative speed. While it wouldn't be a danger to the orbiter for this flight, it might raise many questions regarding future launches.</i>
 
Status
Not open for further replies.

Latest posts