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

[strandedonearth]

*sigh* The biggest mistake I see is allowing you to continue to spout your unscientific baloney on a scientific forum. You refuse to listen (never mind accept) anybody's opinion except your own misguided ones. Quit spouting doom and gloom based on your own made-up numbers.<br />

 

[najab]

><i> they can stop at lift-off in case of severe malfunction...</i><p>The most likely cause of a 'severe malfunction' at liftoff would be the engine itself, and since solids are so simple (literally no moving parts) it is highly unlikely that would happen with a solid, as opposed to a liquid which has hundreds of moving parts and a complex start-up sequence.<p>><i>they can complete the flight in case of a one-two engines malfunction (like with apollo13's 2nd stage rocket)</i><p>What's wrong with you? Are you intentionally being dense? The S-II pretty nearly shook itself to pieces due to POGO (which, by the way, cannot happen with solids) - it wasn't due to superior engineering that it didn't, it was pure luck.</p></p></p>

 

[gaetanomarano]

<br />I don't know the problem that caused the aborted Shuttle flight, but (apparently) this was not due to SSMEs that burned (and stopped) perfectly<br /><br />complex (manned and unmanned) flights are very complex... an abort-signal may come from a simple "battery-low" of a mission-indispensable (satellite or capsule) instrument... or hundreds similar problems, not only from engines

 

[najab]

<blockquote><font class="small">In reply to:</font><hr /><p>I don't know the problem that caused the aborted Shuttle flights, but (apparently) this was not due to SSMEs that burned (and stopped) perfectly<p><hr /></p></p></blockquote><br /><br />Well perhaps you should find out the cause - do you even know what mission it is you are referring to?

 

[scottb50]

It would be simpler to have the payload capable of 0/0 abort rather than the whole vehicle. You might damage the launch pad and the Launch Vehicle would be toast, but it would anyway.<br /><br />With a two stage design te upper stage engines could be used for a limited time at lift off not only to add initial thrust but to allow an abort if needed. Because the nozzles would be sized for vacuum they would not be as efficient, but if the separated the upper stage and got enough altitude to allow the payload to maneuver and land it would be enough.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[gaetanomarano]

<br />no, I don't remember the exact flight, it was (probably) over ten years ago, but probably some uplink's users may know it to find better info<br />

 

[najab]

><i>no, I don't remember the exact flight</i><p>Well then, the intelligent thing would have been to do some research <b>before</b> you posted, get your facts in order and <b>then</b> make a rational, well thought out post, supporting your arguments with quotes and/or links as appropriate.</p>

 

[gaetanomarano]

<br />"...5 on pads aborts..."<br /><br />since I've no exact info about the only on-pad abort I remember... I accept your figure... also because... it's BETTER than mine!<br /><br />"five pads aborts" mean "five shuttles and five crews SAVED" thanks to LIQUID engines ability to STOP after burning!!!<br />

 

[gaetanomarano]

<br />in a CEV launch the "save-the-crew" job must be made with LAS... my suggestion was to INCREASE the crews' safety and, also, try to save the VERY EXPENSIVE earth and orbital moon missions' hardware<br />

 

[gaetanomarano]

<br />I can agree... but not this time, since I've seen the aborted flight WITH MY EYES<br /><br />also, it was only ONE of FIVE on-pad aborted shuttles' flights (see shuttle_guy post)<br />

 

[najab]

><i>"five pads aborts" mean "five shuttles and five crews SAVED" thanks to LIQUID engines ability to STOP after burning!!! </i><p>You really aren't listening are you? Shuttle_guy said that all five of those aborts were caused by the fact that the liquid engines weren't working correctly!</p>

 

[najab]

><i>I can agree... but not this time, since I've seen the aborted flight WITH MY EYES </i><p>But you don't know which mission, you don't know when it happened, you don't know why it aborted - what do you really know about it?</p>

 

[scottb50]

my suggestion was to INCREASE the crews' safety and, also, try to save the VERY EXPENSIVE earth and orbital moon missions' hardware....<br /><br />I think protection of the payload and crew as well as the hardware containing them is the first priority. I seriously doubt you could save the entire launch vehicle as well as the launch structure if a failure occurs at or immediately after liftoff.<br /><br />My point is as long as you are carrying the upper stage anyway there is no reason it shouldn't be used during the initial liftoff, this makes it instantly available if the upper stage is in danger. once at an altitude the payload could detach and return on it's own the stage could be powered down, or shut-down until separation. <div class="Discussion_UserSignature"> </div>

 

[dobbins]

"Well then, the intelligent thing would have been to do some research before you posted"<br /><br />June 26, 1984: A main fuel valve actuator in one of the engines stuck. July 12, 1985: A chamber coolant valve refused to close. March 22, 1993: An oxidizer purge valve jammed on a chunk of O-ring. August 12, 1993: A faulty sensor indicated abnormal fuel flow. And, almost exactly a year later, less than two seconds before the solid rockets were to ignite, an oxidizer pump overheated.<br /><br />http://www.airandspacemagazine.com/ASM/Mag/Index/1996/DJ/abrt.html<br /><br />It took less than a minute to find that with Google.<br />

 

[frodo1008]

You are not totally incorrect here, but that is not the problem with your position. Indeed it is possible for the SRB to fail, but due to the placement of the CEV itself, and its having an almost instant escape mode with its solid motor escape tower the human occupants of the CEV would have an excellent chance of surviving even a catastrophic failure. You are correct in that the launch tower system at the Cape should quite probably suffer great damage, but perhaps it would be useful here to remember that such a failure of the shuttle would not only cause far more damage to the launch system, but quite probable kill all on board the shuttle. Heck, ANY kind of space plane type of vehicle suffers in this manner!!<br /><br />Like drwayne I sometimes grow very tired of giving the same lecture out on thread after thread. Perhaps I should start my own thread just to give it out a final time, and then constantly refer to that thread in this type of situation. However, here I go again:<br /><br />Liquid rocket engines ARE indeed in general safer than solid rocket motors! This is not to say that there are situations in which neither system is completely safe, under any circumstances.<br /><br />Now, the people that build the SRB’s have indeed done a magnificent and highly commendable job of making such motors safe. This is why even though I know liquids to be safer that I still believe in the single stick SRB system for the CEV! The reason that liquids will always be inherently safer is in the testing abilities of the two systems. Once you test a solid rocket motor (and such testing IS still required, even with the problem that I will point out). That problem is that when you test a solid motor that very motor is then used up and gone! You MUST then depend on your manufacturing system entirely to see to it that the production motors that follow from the tested motor are EXACTLY the same in every way (assuming of course, that you have a successful test motor). Now as I ha

 

[mlorrey]

Scottb, the thing you are overlooking is that since the CLV's first stage is SRB based, and the SRB safety and reliability record is the highest of any shuttle component, where even in the event of the Challenger disaster, the SRB that leaked out its o-ring still functioned properly and did not itself fail to complete its mission, that the SRB is a very reliable item. It's mechanical complexity is nearly medeival in its simplicity. The only real things that can go wrong with it are a minor o-ring breach like STS-51, or a complete casing failure, in which case you'd have such a mammoth explosion that you would be guaranteed total crew loss.<br /><br />Given Thiokol's record with all of its large solid boosters, the safety experts have rated the SRB-based CLV as having a projected failure rate of about 3,500 to 1. Given that no launcher in history has been used more than 600 times, this means that even with a 40 year service life, the CLV will, at worst, have a less than 20% chance that just one of its launches will experience total crew loss.<br /><br />From the point of view of crew safety, the SRB based launcher cannot be surpassed, and this is from a person who does not particularly like SRBs.

 

[najab]

<blockquote><font class="small">In reply to:</font><hr /><p>or a complete casing failure, in which case you'd have such a mammoth explosion that you would be guaranteed total crew loss. <p><hr /></p></p></blockquote>Actually, there was a thread a little while back which (if memory serves correct) determined that a solid rocket can't actually explode. You'll end up with flaming chunks of propellant flying everywhere, but no actual explosion.

 

[gaetanomarano]

<br />no, I've correctly read the shuttle_guy post<br /><br />an engine problem (that may happen with ALL engines... also with your car!) caused the launch abort... but... the LIQUID engines' ability to STOP after burning SAVED five shuttles and five crews!<br /><br />BOTH claims are TRUE<br />

 

[gaetanomarano]

<br />I "really" know the most important part about it... liquid-fuel SSME was stopped with Shuttle, launch pad and crew SAVED<br />

 

[najab]

><i>...liquid-fuel SSME was stopped with Shuttle, launch pad and crew SAVED...</i><p>You don't know if the shuttle, launch pad and/or crew were in any danger to start with!</p>

 

[gaetanomarano]

<br />good news... but that "redundancy" was possible thanks to liquid engines... with ALL solid engines the Shuttle can't have this (very high and very good!) "launch-abort-redundancy"<br />

 

[gaetanomarano]

<br />yes, I don't know the danger level of the aborted launch... but, after (liquid) engine stops, the crew was CERTAINLY and UNDOUBTLY alive!<br />

 

[gaetanomarano]

<br />I agree... the better way to save the crew is to abort many miles away from earth... but lift-off is a very important and risky PART of each launch... then, why don't increase crews' safety with an engine that can STOP after burning? ...how you can be SURE that with a solid rocket you will have the time to abort miles away from launch pad?<br />

 

[gaetanomarano]

<br />very good info... it demonstrate the liquid-fuel engines' safety also with complex engines' problems... in fact, all Shuttles and crews you refer was saved<br /><br />I'm perfectly able to do a Google search... but this was unnecessary for this thread... the aborted Shuttle launch is ONLY an example to start a discussion about liquid/solid 1st stage CLV engine<br /><br />ALL peoples know that liquid engines can STOP while solid engine can't<br /><br />the main problem is: CLV must have an engine that CAN stop at lift-off or an engine that CAN'T?<br />

 

[gaetanomarano]

<br />despite a better shuttle may be safer than old shuttles (if good designed) this thread is not a comparison between shuttle and CLV engines<br /><br />it's only about CLV engine<br /><br />in other posts/threads I've suggested to build a 4x, 4 mt., 10-12 tons CEV to launch it with low cost, ready available and known reliable mid-rockets... saving (also) $ billions with CLV research and CEV launches and launch the first CEV years before planned<br />