NO safe liftoff-abort-mode for 1st stage CLV solid fuel SRB

[gaetanomarano]

<br />I can't predict the future to give you the exact reason of a true CLV launch-abort<br /><br />the problem may come from hundreds parts of the CLV or SM or CEV... NOT from the SRB<br /><br />again... the LAS may save the crew (or... exactly... we hope it can) but not the CLV/SM/LSAM/mission/money<br /><br />also... why don't imagine that also the LAS may have a failure that need a launch-abort with (liquid) engine stop?

 

[najab]

gaetanomarano - it's as simple as this: At T-0 if everything is working light the booster, if anything isn't working don't light the booster.

 

[tap_sa]

Q: But what if at T+0.001s an Irish-Italian space buffoon emerges chained to the booster protesting erraneous choice (in his opinion) of technology?<br /><br />A: Laugh and continue launch.

 

[gaetanomarano]

<br />the problems with five Shuttles' flights (ok... due to its engines!) happen a few second after T-0... this is certainly true for the Shuttle's launch-abort I've seen with my eyes... (in TV...)

 

[najab]

><i> this is certainly true for the Shuttle's launch-abort I've seen with my eyes..</i><p>No it's not.</p>

 

[strandedonearth]

Dude: You have proven one more time that you don't know what you are talking about. A few seconds after T-0, the (i.e. T+2 or T+3) the bird is airborne, and shutting the engines down then would just cause a big mess. The SSME's start sequence begins around T-6. T-0 is when SRB start and lift-off occur.<br /><br />So, you don't have a reason why an SRB may need to be stopped or aborted after ignition. The on-pad aborts were caused by all those moving parts in the SSME's, which the SRB's don't have. Without valves to jam or turbopumps to unbalance, there's no potential need to shutdown an SRB after it's lit.<br /><br />The only thing you've ever proven (repeatedly) is that you don't know what you're talking about. When you can prove otherwise, I may take you seriously. Put up or shut up, you're cluttering up these fine boards.

 

[gaetanomarano]

<br />true... it happen before SRB ignition... in the few seconds of SSME burning before SRB... in time to abort the launch and save crew and shuttle (if it was a severe fault... unknown for those have seen it on TV)

 

[drwayne]

gaetano,<br /><br />Stop a minute, and take a deep breath.<br /><br />We have a saying around work, never get emotionally attached to a engineering concept, it clouds your judgement. (Borrowed from that classic movie, "Wall Street")<br /><br />I understand your - preoccupation with the ability to actively throttle a liquid (or for that matter a hybrid engine) - for years I too thought that was the most important thing in manned rocketry. In part, this stems from the teaching of von Braun and my father.<br /><br />As years went on, and I was involved more closely with the guts of rocketry, I began to see that there are other factors in the decisions. I was taught the concepts of fault tree analysis, and understood the concept of the factor that is the probability of occurence convolved with the consequence.<br /><br />And you start to realize that making cut and dried assessments for what is safer is more involved that just "you can shut it down"<br /><br />As has been pointed out, solids and liquids each have positives and negatives, and those can and do change depending on the application.<br /><br />We love a good, rational technical discussion on the merits of different designs.<br /><br />What we do not like a discussion that starts from a strong statement about the engineering, and attempts to argue that position into correctness. Ignoring when the statements you make, like the abort saved the shuttle, when you are told that it did not such thing just makes you look like someone who wants to prove that their thesis is true, not to discover whether it is true.<br /><br />That is the nature of the scientific process, the examination of a thesis for its truth. An objective analysis of the facts. <br /><br />I am pretty good at examining my postulates for faults, as I am married and by definition that makes me wrong most of the time. <br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[steve82]

Isn't this thread dead yet?

 

[drwayne]

Pretty much.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[gaetanomarano]

<font color="yellow">would not have been an abort</font><br /><br />probably the difference is from NASA procedures and common terms<br /><br />probably for NASA procedures an "aborted-flight" come only when engines burns or only from shuttle lift-off and over<br /><br />in a Formula1 race (only as example) the race may stop before it starts... simply if one of the cars' engines stops<br /><br />for a "non-NASA-engineer" a flight that stops ten minutes before any engines ignition (due to a sensor alarm) appear "aborted"<br /><br />but, probably, for NASA procedures its only a flight "delayed" and not "aborted"<br /><br />"delayed" or "aborted"... if a Shuttle flight continue (instead of stop before SRB burn) despite there is a "problem" the crew and the shuttle are at risk<br /><br />but if you say to me that a flight stop at this point in not and "abort" but only a "delay" for NASA procedures... ok... from now I will call it "a delay that saved the crew and the shuttle"<br />

 

[strandedonearth]

Actually, SG was saying that a mission would not be aborted after liftoff for a fault in the redundant systems. But the countdown would be aborted if a fault was found in the redundant systems before liftoff.<br /><br />Quit trying to argue semantics to prove yourself right. Be a man and be accountable for your mistakes, for once. Oh, wait, to be a man to an Italian means to be macho to the point of muleheadedness, and never admit a mistake.

 

[gaetanomarano]

<br />I've no problem to accept (since it is logic) that after lift-off a mission can't be aborted because it is lethal (the rocket crash on itself) and the only way is to try to reach the max quote possible (to save the launch pad) while ejecting capsule and crew with LAS<br /><br />but if Shuttles' SSMA burns some seconds before the SRB (and five launches was stopped at this point) there must be a reason!<br /><br />I think you must ask NASA (not me) to know... "why you don't start all engines togheter?"<br /><br /><br /><br /><font color="yellow">however, we have given our opinion about this problem, so, if there are no further replies, I think that the discussion of this thread is complete<br /><br /><br /></font>

 

[SpaceKiwi]

<blockquote><font class="small">In reply to:</font><hr /><p>but if Shuttles' SSMA burns some seconds before the SRB (and five launches was stopped at this point) there must be a reason!<p><hr /></p></p></blockquote><br />The SSME's start before the SRB's because the SSME's take a little time to develop full thrust, and also to ensure that they are performing nominally before SRB ignition. <div class="Discussion_UserSignature"> <p><em><font size="2" color="#ff0000">Who is this superhero?  Henry, the mild-mannered janitor ... could be!</font></em></p><p><em><font size="2">-------------------------------------------------------------------------------------------</font></em></p><p><font size="5">Bring Back The Black!</font></p> </div>

 

[gaetanomarano]

<br />this is true also for past flights like SaturnV... lift-off start a few seconds after engine-ignition<br /><br />this little delay give to Shuttle the time to stop them (if necessary) and may give to (liquid-engines) CLV the time to stop (if necessary, of course) while the (fast start) SRB can't<br /><br />it's simple

 

[strandedonearth]

All liquid fuel engines require time to spin up to full thrust due to all the moving parts. This conveniently also gives a few seconds of checkout time, to check all those moving parts. SRM's reach full thrust almost instantly because there are no moving parts. Thus there is nothing to check out.

 

[gaetanomarano]

<br />as I've explained many times here... with a completely new CEV/SM/CLV "system" the problem that need a launch-abort (expecially in early, low-experience, flights) may come from different places (before, while and after lift-off) ...and, probably, NEVER from 1st stage engine...

 

[strandedonearth]

And as I've explained before: can anybody point out any launch where the vibration of ignition has created a fault elsewhere in the stack that was not noticed prior to ignition? The rest of the stack will have been shaked and baked in testing to find any such faults already. And if there is such a problem, it's not the end of the world, the crew can always use the LAS to abort.<br /><br />Your opinion, my opinion, agree to differ and move on.

 

[gaetanomarano]

<br />can you be SURE that this can't happen with a completely new vehicle?<br /><br />can you be sure that the Apollo13 tanks' problem was not (really) born at launch (due to mechanical stress) and to-day's advanced sensors can't evidence it while launch-stress?<br /><br />why risk the crew and lose rocket/pad/LSAM/mission/money if the (liquid) engine can (simply) stop and save the full packet?

 

[strandedonearth]

Because the chances of that happening are so low that designing around that particular fault mode would cost too much for a miniscule reduction of risk.<br /><br />IIRC correctly, the problem with Apollo 13's oxygen tank started when it was dropped in the factory. It *may* have been exacerbated by the stresses of launch, but you can't have sensors on absolutely everything.

 

[gaetanomarano]

<br />many cars' problems born at its factory... and come real only when you drive (launch...) the car (rocket) at high speed

 

[rubicondsrv]

gaetanomarano <br /><br />please stop repetitively posting the same thing .<br />you have been trolling for too long and it must stop.<br /><br /> <br /> <div class="Discussion_UserSignature"> </div>

 

[gaetanomarano]

<br />I've already said (some posts ago) that the discussion of this thread appear complete (if I don't receive further replies) ...but don't "ORDER" to me what I MUST DO... I don't receive "orders" from you!<br />

 

[carp]

SILENCE! Genius at work. http://img501.imageshack.us/img501/8446/forumtroll2my.jpg

 

[najab]

This thread is serving no useful purpose any more. If there isn't more than one objection, I shall close it.