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

najab · Dec 27, 2005

>...the Shuttles' liquid engines' STOP saved five crews (up to 40 astronauts alive!) and five Shuttles...What you seem unable to comprehend is that before you can say that the RSLS aborts 'saved' the Orbiters and/or crews you first have to prove that the launches would have resulted in a loss if they had gone ahead. Shuttle_guy (who, unlike you, was actually there for each of them) has said that this is not the case.

drwayne · Dec 27, 2005

"the Shuttles' liquid engines' STOP saved five crews (up to 40 astronauts alive!) and five Shuttles (since they was only 3 or 4 in the same time... up to $20 billion saved) ... but this don't appear sufficient to you (and great part of uplink's users) to agree with me about this point!" The reason is that your analysis is superficial. As was noted earlier in the thread, each of the shutdowns to which you refer were the result of a failure in the liquid fueled engines *themselves*. The caused the shutdowns themselves. Which is better, to have the capability to shut down due to faults in a liquid system, or to not have the faults in the first place. Wayne <div class="Discussion_UserSignature"> "1) Give no quarter; 2) Take no prisoners; 3) Sink everything." Admiral Jackie Fisher </div>

SpaceKiwi · Dec 27, 2005

Interesting. Do the motors fire sufficently 'true' so as to require a minimal degree of clamping perpendicular to the direction of thrust? <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

gaetanomarano · Dec 27, 2005

what is the (real) problem for you to use a liquid-multi-engines 1st stage CLV?

frodo1008 · Dec 27, 2005

In actuality gaetanomarano's argument does indeed have some merit. Liquid engines are inherently safer for the reason that I have already pointed out. However, in the same post I also pointed out that the makers of the SRB's for the shuttle have worked hard enough at making these particular solid motors safe in themselves that the difference in safety in this case is too small to be any kind of a problem (if they hadn't have done this we would have lost the entire shuttle fleet by now!). Also, in placing the CEV capsule at the top of the entire launch vehicle, and having an almost instantaneous safety solid motor eject system as a part of that capsule, guarantees that the crew has a very good probability of living through almost any kind of launch accident. Not only this, but the cost of the SRB itself is quite inexpensive, which I believe is the main reason for continuing to use these motors! This helps to keep the overall system costs down, which I think is the point of using both the SRB's, and the single SSME for this vehicle!! As this is what NASA is going to do (somehow, I don't think they are going to listen to any of the amatuer advice from this site, let alone that of someone from another country), the entire discussion (while perhaps entertaining) is MOOT!

Swampcat · Dec 27, 2005

"what is the (real) problem for you to use a liquid-multi-engines 1st stage CLV?" What is the real problem with you accepting the solid 1st stage? <div class="Discussion_UserSignature"> ------------------------------------------------------------------- "I hold it that a little rebellion now and then is a good thing, and as necessary in the political world as storms in the physical. Unsuccessful rebellions, indeed, generally establish the encroachments on the rights of the people which have produced them. An observation of this truth should render honest republican governors so mild in their punishment of rebellions as not to discourage them too much. It is a medicine necessary for the sound health of government."Thomas Jefferson </div>

gaetanomarano · Dec 27, 2005

it's a probability, of course, but, if the Shuttle NEED all engines that works well for a safe and perfect flight, a big failure in ONE of its engines (that need a launch-abort) IS an high risk for the Shuttle and the crew (since the Shuttle has no LAS) please consider that, now, we can talk of "aborted-launches" and may "argument" about "if" and "how much" that problems was really dangerous... because... THANKS TO LIQUID ENGINES... that launches was aborted... with solid engines only... probably we now may talk only of the 3rd or 4th Shuttle accident........

gaetanomarano · Dec 27, 2005

the fact that the main abort reason of a Shuttle was the SSME or the SRB or the Main Tank don't mean that, with another vehicle and another rocket, the problem that need a launch-abort may ONLY happen in its engines I think that the high probability of an abort-launch-signal may come from one of the hundreds completely new devices of the CEV/SM/CLV system (it may be the last time that I must repeat this simple concept here?)

najab · Dec 27, 2005

>....a big failure in ONE of its engines (that need a launch-abort)...And yet you downcry a vehicle which only has one engine that cannot fail in a manner that would require a launchpad abort.

SpaceKiwi · Dec 27, 2005

<blockquote>In reply to:<hr />what is the (real) problem for you to use a liquid-multi-engines 1st stage CLV?<hr /></blockquote> Thank-you for asking. I remain singularly unconvinced that a multi-engined liquid-fueled 1st stage offers any advantage whatsoever. I do not see the fact that a solid cannot be shut-down once ignited as a negative, given the way the solid is to be used in conjunction with a launch-escape system. On balance, a solid 1st stage would appear to offer (to my untrained eye) a far simpler and more reliable method of boosting the CEV off the pad. I would suggest that a multi-engined liquid-fueled approach will only increase the statistical probabilty of mission failure. That's post 1500. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

gaetanomarano · Dec 27, 2005

ok... the SRB makers have worked hard and the SRB is perfect... but I don't suggest a liquid engine ONLY for an SRB failure but fro HUNDREDS DIFFERENT POSSIBLE PROBLEMS true... the LAS will save the crew (I've repeated this a dozen times) but can't save the CLV, the launch pad, and the ($6-8 billion) missions... the liquid engine CAN stop work and CAN save ALL (or "may save", if you prefer)

najab · Dec 27, 2005

>I don't suggest a liquid engine ONLY for an SRB failure...If the SRB doesn't fail, it's not going to be there any more to damage the pad, etc... It's going to be flying tens of thousands of feet up into the air and will land dozens of miles downrange. What exactly are you saying - do you even know?

gaetanomarano · Dec 27, 2005

read my posts in this thread... I can't repeat them dozens times

gaetanomarano · Dec 27, 2005

if I understand your question... I don't suggest multi-engines stages with 100% of thrust but with 120%+ of thrust if the total thrust of the multi-engines stage is only 100% of what the rocket need, a failure in ONE engine is like a failure in ALL engines or a failure in the SINGLE CLV engine with "redundant-thrust" five-engines, the rocket may reach the orbit also with four working engines... plus the advantage of an easy and launch abort after 1st stage engines burning

gaetanomarano · Dec 27, 2005

the solid rocket is simple and may work well but can't stop if necessary the liquid-multi-engine is really redundant if its engines will give a sufficient thrust also if one engine will fail, the, they must be overdesigned (probably this is not the right word...)

SpaceKiwi · Dec 27, 2005

<blockquote>In reply to:<hr />What exactly are you saying - do you even know?<hr /></blockquote> Yes, gaetanomareno, what ARE you saying? Where is this ficticious fault that requires an on-the-pad abort? Is the toasted sandwich maker on the blink perhaps? If all systems aren't nominal prior to the SRB ignite at T-0, the rocket doesn't go. Once the rocket does launch remarkably little is happening, save for the solid reliably (statistically more reliable than several liquids) boosting, the rocket vectoring towards it's pre-determined orbit entry point, and the crew white-knuckling it. <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

gaetanomarano · Dec 27, 2005

true! (and... "I know"!) ...only... on which land (or ocean) do you want to burn the giant (and very very expensive) LSAM+booster duo (launched with the very very expensive SDHLV) after its 30 days life? 12 moon missions - 1 moon mission = 11 moon missions

SpaceKiwi · Dec 27, 2005

<blockquote>In reply to:<hr />the solid rocket is simple and may work well but can't stop if necessary<hr /></blockquote> Can you please cite an example where it has been necessary to stop a solid boosting post-STS 51L, when the current-design SRB was introduced? <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

gaetanomarano · Dec 27, 2005

I can "invent" dozens of possible reasons of a possible launch-abort after the high-vibration-stress of CEV/CLV engines burning ("invent" because the real vehicle don't exist) ...but I can't know now which (real) problem may happen... NO ONE can know now which problem may happen... probably also in the first (perfect) CLV launches no one may imagine which problem may happen... we can know "which" problem will happen only "when" it will happen (and will need a FAST engines' STOP!) with the Shuttles the high-vibration-launch-stress come BEFORE the SRBs burning... in the very few seconds of SSME's only burning

SpaceKiwi · Dec 27, 2005

<blockquote>In reply to:<hr />I can "invent" dozens of possible reasons of a possible launch-abort after the high-vibration-stress of CEV/CLV engines burning<hr /></blockquote> In other words, you are UNABLE to cite a REAL-WORLD example requiring the immediate shut-down of a SRB 1st stage. Nor are you able to describe how a scenario requiring an immediate 1st stage shutdown has managed to by-pass the multiple redundency built into critical systems. Nor are you able to describe how any scenario puts the individually pressure-suited crew in life-threatening danger. <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

gaetanomarano · Dec 27, 2005

I try to better explain... the CEV/SM/CLV is not "a rocket and a capsule" but a complex "system" all parts of this "system" need to work for a successful mission you can't accomplish the mission if an essential part of the "system" will fails before, while or after the launch NASA will put some sensor to control the entire "system" if something wrong will occur BEFORE the launch, simply the launch will be postponed but if a problem will occour while engines burns (due to launch-stress) the rocket must stop you ask me about the possible failures I give you two examples (may be right or wrong... no matter... if they are "wrong" other problems may be "right"): - the pressure of one of the SM tanks goes under its safe level - the orbital navigation system don't receive the energy it need these (hypothetical) problems may not affect the launch... it may be perfect and the CEV may arrive in orbit... but can't continue the mission... so, if a sensor will detect a problem on a device that the CEV will use the next week, there is no reason to send the CEV in orbit

SpaceKiwi · Dec 27, 2005

<blockquote>In reply to:<hr />I give you two examples (may be right or wrong... no matter... if they are "wrong" other problems may be "right"): - the pressure of one of the SM tanks goes under its safe level - the orbital navigation system don't receive the energy it need these (hypothetical) problems may not affect the launch... it may be perfect and the CEV may arrive in orbit... but can't continue the mission... so, if a sensor will detect a problem on a device that the CEV will use the next week, there is no reason to send the CEV in orbit <hr /></blockquote> I doubt either problem, as described, would not be covered by redundent systems, although I'm not sure I know what you mean by 'energy' in the case of orbital navigation. Nonetheless, neither scenario really requires or benefits from an immediate shut-down of a liquid-fueled 1st stage and presumed landing somewhere east of KSC. Far better (and, indeed, safer) to 'abort' to LEO, assess the situation, see if it can't be rectified and only then return to Earth in a planned manner if the problem can't be trouble-shot. <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

gaetanomarano · Dec 27, 2005

the "problem" are only "example" to give "a problem" not %............... this post was SELF-DELETED by servers or my browser (I don't know) I will try to remember the exact text and I will repost it

SpaceKiwi · Dec 27, 2005

I'm sorry gaetanomarano, your 'what-if, what-if, what-if' scenarios simply do not stand up to simple scrutiny. What if a giant Stay-Puft Marshmallow Man walks out of the Atlantic at KSC and lifts the CEV off the pad and snaps it in two? At some point you have to ascribe a high level of competence and expertise to the designers, builders and operators of the CEV. Moreover, you can only take history as your guide as to how a new vehicle might perform. All things considered, the STS has performed extremely well given it's complexity. I'm not convinced that whatever system followed Apollo would have had any better operational record than Shuttle, given everything that Shuttle has accomplished. Many of these supposed sensor-warnings don't occur now on the much more complicated Shuttle, and I see no reason to believe Mission Control is going to have red lights coming out the waazoo on this new vehicle. These people know how to put together propulsion sub-systems and navagation sub-systems and environmental sub-systems, etc, etc. My expectation is that this new vehicle will be simpler, safer and more reliable than anything that has gone before it. Annnnnd, my expectation is that it will have an unprecedented level of redundency built into the system to cover for all reasonable contingencies. Life is risk, gaetanomarano. The CEV looks to cover all reasonably anticipated ones. <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

gaetanomarano · Dec 27, 2005

all complex systems have some "red lights"... and spaceflights are VERY complex system not even the best engineers can build perfect vehicles... this is the reason why "complex systems" (also with high redundancy!) must have many "red lights" and some "abort options" you will see... "the best CEV/CLV possible" will have MANY "red lights" and "abort options" ALSO at lift-off (like Shuttles and all past and future vehicles) ...for crew ...missions ...(and investments) safety

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

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