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

[gaetanomarano]

<br />many years ago, I've seen on TV an "aborted at lift off" Shuttle launch (I don't remember the exact year and shuttle flight)<br /><br />the SSMEs was stopped and flow with water to cool the engines, so, both shuttle and crew, was saved<br /><br />you know that shuttle's SSME burns a few seconds before SRBs and, if all sensors and computers give their "ok", also SRBs burns and the shuttle's flight starts<br /><br />then, the liquid propellent SSME is safer than SRB's solid fuel<br /><br />I think that Shuttles' retirement (without a new shuttle) is a giant mistake... but also the VSE/ESAS plan is FULL of (little and big) "inner mistakes" like...<br /><br />1st: CEV over-dimensions<br /><br />2nd: 99% expendable vehicles<br /><br />3rd: very high costs<br /><br />4th: very poor number of flights/astronauts in next 20 years (1/10th of past 25 years Shuttles' flights)<br /><br />5th: losing of ALL Shuttles' space-assembly/repair ability<br /><br />etc. etc. etc.<br /><br />I think that a further mistake is the use of a solid-fuel 1st stage for CLV<br /><br />despite it uses some "old" parts, CLV is a completely NEW rocket, that, like ALL new rockets, may have some UNEXPECTED design and safety problems<br /><br />these "problems" may be a great risk for crews expecially if a problem will happen at lift-off<br /><br />just imagine that one CEV/CLV sensor or computer will order to ABORT the flight in the first seconds (like the mentioned aborted shuttle's flight)<br /><br />the consequences may be:<br /><br />1. highest risks for crew... since the LAS must make its faster and maximum work to reach the right height for safe parachutes opening<br /><br />2. the explosion of the entire CLV<br /><br />3. the (possible) complete destruction of the CLV's launch pad<br /><br />4. a giant quantity of money lost... $1 billion for CEV/SM/CLV, $5 billion for the LSAM+booster (+SDHLV rocket) that will remain in orbit (and, after its ONE-MONTH life, must be burned in atmosphere) and much more for the CLV's new launch

 

[drwayne]

You can get some interesting discussions about the safety of liquids versus solids.<br /><br />To many (and myself earlier in my career), the inability to "turn off" a solid was by definition equal to solids are not as safe as liquids.<br /><br />However, there is more to safety than whether there is an abort mode. Clearly, is one looks at the thrust provided by a given engine versus the mechanical complexity (and by extension the possibility of mechanical failure), solids have a definitive edge. They have no high speeds pumps and complex piping to support bringing fuel and oxidizer together at high rates.<br /><br />Some of us who have been associated with the history of liquid engines have seen some - interesting events associated with failures of liquid engines. (And I recommend finding a way to get hold of the now out-of-print book "Ignition" by John Clark). <br /><br />By the way, I have seen liquids take out launch facilities with great effeciency as well. Fortunately always either on film or at a safe distance. <img src="/images/icons/wink.gif" /><br /><br />Solid failures on the pad have been much rarer, in the past, they tended to occur in flight due to case burn throughs - but that has gotten much much rarer with more modern process controls.<br /><br />Wayne<br /><br /> <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[gaetanomarano]

<br />the abort "order" at lift-off don't need to come only from the "simple" solid-rocket but from the (more complex) 2ndstage/SM/CEV (like was with mentioned aborted shuttle flight)<br /><br />also, it's very probable that a similar occurency will happen because...<br /><br />1st stage: old engine but completely redesiged to work alone<br /><br />2nd stage: old engine but completely redesigned for air-start<br /><br />SM: completely new design and never used before (not 100+ times like Shutte and Soyuz)<br /><br />CEV: completely new design and never used before (not 100+ times like Shuttle and Soyuz)<br /><br />99% of CEV/SM/CLV system is NEW and without long-time tests!<br />

 

[gaetanomarano]

<br />true, any vehicle may have its own risks... but it's clear that a solid-fuel rocket can't be stopped after burning, so, the risk to destroy, both, very expensive CLV and launch pad, is HIGHER than with liquid engines<br />

 

[nacnud]

<font color="yellow">but it's clear that a solid-fuel rocket can't be stopped after [while?] burning<br /><br /><font color="white">No you can't stop a soild motor from burning but you can stop it from thrusting, or greatly reduce the thrust. This is done my removing the containment from around the fuel, for example by taking the top off the engin or perhaps breaking the motor into sections.</font></font>

 

[tap_sa]

And exactly how would you safely land a CLV sized all-liquids booster that aborts at T plus a few seconds?

 

[drwayne]

"so, the risk to destroy, both, very expensive CLV and launch pad, is HIGHER than with liquid engines"<br /><br />No, that is not neccessarily true. Liquid fueled engines have their own probability of failure, and are fully capable of destroying everything - see the drwayne favorite POGO stories about the near loss of Apollo 13 - I have posted them until people got sick of it.<br /><br />In fact, I have seen analysis that talks about the time between warning of an untoward event and the loss of the vehicle that indicate that liquid fueled engines have significnatly less warning of catastrophic failure - leaving little or no time for any abort type actions to save the craft.<br /><br />Avoid falling into the trap of seeing one factor, and on the basis of that one factor making a global statement about safety.<br /><br />Wayne<br /><br /> <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[gaetanomarano]

<br />yes "while" not "after"<br /><br />reducing thrust at lift-off (and if LAS will works well) the crew is saved but the rocket my back-crash (right term?) to the (expensive) launch pad<br /><br />the main SRB's problem is its SINGLE engine design<br /><br />

 

[gaetanomarano]

<br />if the engine must be stopped you save the CLV and the launch pad with a (shuttle-like) abort at lift-off... and it ALREADY appear to me a VERY GOOD advantage!<br /><br />to reduce the risks AFTER lift-off, the SINGLE big (solid or liquid) engine must be changed with a redundand multi (liquid) engines design<br />

 

[gaetanomarano]

<br />an accident may happen also with liquid engines, of course, no one can build 100% safe rockets!<br /><br />but stop the liquid engines at lift-off (that remain the MOST COMPLEX and RISKY part of a flight) may...<br /><br />1. save one (very expensive) CEV/SM/CLV<br /><br />2. save the (very expensive) CLV's launch pad<br /><br />3. save one (very expensive) LSAM+booster/moon mission (but only if the CEV/CLV problem must be repaired in time to try again the launch)<br /><br />4. save the crew (yes... the LAS may save them from launch pad... but it's BETTER if they NEVER TRY its work in a true accident!)<br /><br />do you not think that these are very good advantages?<br />

 

[tap_sa]

<font color="yellow">"if the engine must be stopped you save the CLV and the launch pad with a (shuttle-like) abort at lift-off... and it ALREADY appear to me a VERY GOOD advantage! "</font><br /><br />There's no advantage, there's a <i>difference</i>. Starting a modern liquid fueled engine is a delicate procedure of opening numerous valves in precise timing to spin up turbopumps and pickup thrust in an orderly fashion. It <i>requires</i> several seconds (plus STS is timed to wait the 6+ second 'twang') during which you can still chicken out and halt the launch.<br /><br />With SRBs the story is very different. You think it's OK to launch, pop the mortar and after a fraction of a seconds it's full speed ahead.<br /><br /><font color="yellow">"to reduce the risks AFTER lift-off, the SINGLE big (solid or liquid) engine must be changed with a redundand multi (liquid) engines design "</font><br /><br />uh, what risk? Risk of engine stopping? Didn't you just whine couple posts ago that solid motor is very difficult to stop after lit. Surprisingly you got that right.

 

[gaetanomarano]

<br />the OLD (100% liquid engines) saturnV have worked well... in the aborted Shuttle flight the SSMEs was stopped in time to save shuttle, crew and launch pad<br /><br />the redundant multi-engine design is not safe because it can ABORT the missions but because the rocket can CONTINUE and COMPLETE the launch using only the working engines<br />

 

[drwayne]

"the OLD (100% liquid engines) saturnV have worked well"<br /><br />As I stated earlier, these very same engines nearly scattered Apollo 13 all over the sky.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[tap_sa]

<font color="yellow">"the redundant multi-engine design is not safe because it can ABORT the missions but because the rocket can CONTINUE and COMPLETE the launch using only the working engines"</font><br /><br />Your original complaint was about situation where abort happens right after launch. You went to elaborate that abort command isn't necessarily due to malfunction in first stage but in seconds stage or in CEV. So what's it gonna be? You just ignore the abort signal and keep firing your trusty liquid multi-engine stage because it can continue and complete it's task while, say, stage two keeps disintegrating?

 

[drwayne]

In the case of the shuttle SRB, such an operation is realy somewhat more of a range safety operation, rather than an abort operation, is it not?<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]

<br />"...well, with one <font color="yellow">(lethal, for seven astronauts)</font>exception..."<br />

 

[gaetanomarano]

<br />no!<br /><br />the Apollo13 accident was due to a tank explosion not a liquid engines malfunction<br /><br />and the Apollo13 was saved thanks to the LIQUID descend-stage LEM's engine<br /><br />the same LIQUID and THROTTLEABLE engine was used to correct the moon to earth route<br /><br />just imagine if LEM engine was solid-fuel... (fortunately for apollo's crew it was impossible to be "solid")<br />

 

[gaetanomarano]

<br />no!<br /><br />the main SRB will be similar but, since to-day's SRBs receive energy and commands from Shuttle, the CEV's SRB will need many changes in its electronics that is VERY IMPORTANT for a SAFE launch... remember the first Ariane5 flight... it was aborted after launch (and four "unmanned" satellites destroyed with the rockets) due to a little rocket's computer "programming error"<br /><br />also, the rest of the CEV/CLV system is completely new, so, the abort-order at lift-off may come from other part of the system<br /><br />

 

[drwayne]

"no! <br /><br />the Apollo13 accident was due to a tank explosion not a liquid engines malfunction "<br /><br />You need to study your Apollo 13 history a little better.<br /><br />I was NOT referring to the tank failure. <br /><br />I was referring to the second stage, center engine POGO that basically tore the center engine loose from its engine mounts. The second stage was seconds away from failure. (Less than that really)<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]

<br />you can disagree... but the solid-engine don't agree with you and don't stop burning...<br />

 

[gaetanomarano]

<br />now I understand you post... but this CONFIRM my claim about multi-engines redundancy... despite center engine fails, the flight was not aborted because four engines was sufficient to enter LEO<br /><br />do you think that this may happen 100% times with the <font color="yellow">SINGLE</font>CLV's 2nd stage new (air-started) SSME engine?<br />

 

[drwayne]

Actually, no, the failure of that one engine nearly took out the whole flight. It was luck that it did not. Not redundancy. <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]

<br />it's clear that liquid engines can't give 100% launch success... they can only INCREASE the launch success probability because...<br /><br />1. they can stop at lift-off in case of severe malfunction, and...<br /><br />2. they can complete the flight in case of a one-two engines malfunction (like with apollo13's 2nd stage rocket)<br /><br />of course, if a severe malfunction will happen, also a liquid engines' rocket must abort<br />

 

[gaetanomarano]

<br />single 1st stage engine + singe 2nd stage engine mean: "100% of hardware MUST work well 100%"<br /><br />with many engines, the flight may continue and the crew will arrive (alive) in orbit instead of use the LAS<br /><br />then, a (good made) multi-engine rocket is SAFER than a single engine (and may save lots of money avoid many aborted flights...)<br /><br />

 

[gaetanomarano]

<br />true... the crew may be saved with LAS... but the (incredibly expensive) CLV, LSAM, SDHLV and moon mission will be LOST<br />