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

[mlorrey]

"in last 50 years 100% of manned spaceflight was (successfull) made with (reliable) full-liquid or most-liquid engines' systems... now many want to launch a completely new vehicle "<br /><br />You are getting to be a broken record that can't learn from new information. You fail to recognise that, given US experience with ICBMs, there are actually more launches with solid rockets in the US space program history than with liquid. There have been 20 years of successful MX missile tests, and 40 years of successful Minuteman missile tests, plus Scout, and many others. Solid rockets have a far more reliable operational record than liquids. The SRB has operated for 20 years with only one malfunction. This record is far better than any liquid system the US has operated.

 

[gaetanomarano]

<br />I think that, if the LAS will be well made, well tested and fast-acting, the crew will not risk so much (only a big scariness!) but the risk to lose all the missions' hardware may remain<br />

 

[gaetanomarano]

<br />you can't compare ICBMs with manned orbital flights<br /><br />the ICBM's launch record may be good but it DON'T NEED to be good<br /><br />ICBM's don't launch nothing in orbit and it's use may be only to launch dissuasion and retaliation weapons<br /><br />so, they may have liquid, solid, ice, ion, fusion engines... no matter... they must only remain on earth (or hit 50% of target if used)<br /><br />the realty is that MANNED spaceflights was done ONLY with full or most LIQUID engines' rockets<br /><br />also... solid engine is NOT the only CLV problem...

 

[SpaceKiwi]

<blockquote><font class="small">In reply to:</font><hr /><p>the ICBM's launch record may be good but it DON'T NEED to be good<p><hr /></p></p></blockquote><br />Excuse me???!!! The record might be good, but because it doesn't <b>need</b> to be good, it doesn't count that it is good!<br /><br />gaetanomarano, are you sure there's not a little of the Irish mixed in that Italian family tree somewhere? <img src="/images/icons/wink.gif" /> <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 />I try to better explain my opinion...<br /><br />I've read that the italian rocket VEGA (ready to launch in next 2 years) will have three solid-fuel stages<br /><br />since it will launch up to 2.5 tons in LEO for only $20 million per launch it may have a great commercial success (that mean "many launches") and, if it is well designed, may have a good launch record<br /><br />but, EACH stage of this rockets will have engines that can be only burned... not closed... not controlled<br /><br />so, also if it will have a 100% flight record, it don't appear "safe" to me for "living-payloads" because I think that ALL rockets with "living-payload" (like some astronauts...) MUST have engines that we can STOP and CONTROL... from liftoff -10 seconds to last second of last stage engines' burning!<br /><br />probably, with a liquid booster (and a good fire leakage sensor) the Challenger's crew may still be alive<br />

 

[josh_simonson]

SRBs don't have an escape/destruct system built into them at the moment because that'd simply destroy the orbiter. It seems quite possible though, that given a very serious problem a few explosive bolts could unhitch 2 segments in the SRB and it'd pop open and lose thrust - at the same time the escape tower can fire and get the crew away from the rest of the rocket.<br /><br /> />also... solid engine is NOT the only CLV problem... <br /><br />Everything has problems, the engineer's job is to find a solution that has the fewest problems. Horizontal integration is a problem with the STS that resuted in both lost orbiters (with lack of a launch escape system and an unprotected TPS as contributing factors). In anything as complex as a man-rated orbital launcher, one can point problems out all day long. This is expensive, that is somewhat risky, this other thing is an immature technology. Folks more knowledgeable than any of us have to consider the flaws in various designs and pick one that's the most robust, reliability, timing and cost-wise.<br /><br />Any large spaceplane will be unable to integrate an escape system without a prohibitive mass penalty, they gave up on it with the shuttles, and both crews might have been saved by one. <br /><br />One thing is for sure though, NASA (and probably nobody else either) will ever build a horizontally integrated rocket where people (and TPS) are adjacent to the first stages rather than on top of them. <br /><br />With vertical integration, a TPS that's fully protected until minutes away from re-entry, and an escape tower, the CLV/CEV is immune to all the lethal failure modes that the shuttle suffered. Management undoubted made these items safety requirements. Note that NASA's plans were for a mini-shuttle, similar to kliper, until columbia - then the requirement for a fully protected TPS forced them back to capsules for safety reasons.

 

[scottb50]

The real point is there is bound to be a failure no matter what you use, at some time no matter how safe you make it, they call that statistics by the way, theres a number for everything, when your numbers up it's up, but it will come up.<br /><br />That's why the only option may be getting the hell out of Dodge. First engines to start are the upper stage then the main engines followed by SRB's. Failure of a second stage engine you shut down and evacuate, other failures allow different options but until SRB burnout separating the second stage offers the best option. Only a few thousand feet would be needed for 0/0 escapes, inert payloads parachute down and manned vehicles follow different procedures depending on when they become self sufficient. <div class="Discussion_UserSignature"> </div>

 

[SpaceKiwi]

<blockquote><font class="small">In reply to:</font><hr /><p>MUST have engines that we can STOP and CONTROL... from liftoff -10 seconds to last second of last stage engines' burning!<p><hr /></p></p></blockquote><br />Must it? No, I don't think it 'must' at all. It must provide reasonable safeguards to jettison the crew in the unlikely event of a catastrophic failure of the SRB. As I understand the current design, I think those safeguards are being adequately provided for.<br /><br />Regardless of your method of rocket propulsion, once you get so far into the fault tree that launch escape becomes a likely event, you are putting your life in God's hands. It becomes a crap shoot. And, while I'm certainly no expert, even if the Shuttle boosters had been liquids on STS-51L I feel reasonably confident in saying the crew would have still been unlikely to survive. <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 />since "everything has problems" there is no need to build "things with problems inside"<br /><br />the BEST space engineers of the world have made the side-mounted Shuttle mistake... why (now) similar (good) engineers CAN'T make similar mistakes?<br /><br />I think that CEV/CLV is a bad design and that engineers have made a new mistake... this is "my" opinion

 

[gaetanomarano]

<br />in the Challenger's accident the fire leakage was between two SRB's rings... near the main Shuttle's tank (that explodes)<br /><br />a liquid rocket may have many faults... but not THIS kind of problem... so, the Challenger's crew may still be alive with two liquid boosters<br />

 

[SpaceKiwi]

<blockquote><font class="small">In reply to:</font><hr /><p>in the Challenger's accident the fire leakage was between two SRB's rings... near the main Shuttle's tank (that explodes) <br /><br />a liquid rocket may have many faults... but not THIS kind of problem... so, the Challenger's crew may still be alive with two liquid boosters<p><hr /></p></p></blockquote><br />Again you are changing tune mid-stream, gaetanomarano. I was addressing your assertion to me on the previous page that liquid boosters and a 'good fire leakage sensor' might have resulted in Challenger's crew surviving. Which I took to mean you are suggesting a booster fire is picked by a sensor and is then shut-down. That would therefore necessitate the other booster being shut-down to equalise the thrust. Which would then leave you dramatically short of power.<br /><br />Someone like SG or najaB would know correctly, but I doubt that would be a survivable condition at that point in flight under any kind of scenario. <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 />due to its design... Shuttle can't abort its flight and save the crew at low altitudes<br /><br />it may be safe BEFORE the SRB's burning and at high altitudes (if the abort system works well)<br /><br />probably, in the specific Challenger's case, the accident's altitude was sufficient to abort the flight, abandon the main tank and try to glide to earth... probably... but only with liquid boosters and good sensors... with solid-boosters all exploded quickly

 

[scottb50]

Sure it would, the second stage separates and goes it's own way. With the Second Stage on top of the first stage, the SSME's on the ET not on the Shuttle.<br /><br />Not only would the second stage engines increase payload they would allow a safer vehicle, a passive engine failure can be dealt with, a catostrophic failure can be escaped from. <div class="Discussion_UserSignature"> </div>

 

[najab]

Impossible to say - the flight profile would be different with liquid boosters.

 

[najab]

><i>ONLY if NASA will build a four-seats 12 tons CEV and launch it with a (man-rated) ready available (low cost and realiable) mid-rocket...</i><p>And precisely which low cost, readily available, reliable, man-rated rocket would that be?</p>

 

[gaetanomarano]

<br />many american and non-american rocket can launch 12 tons (or more) in orbit<br /><br />some rockets (like Ariane5) are used for satellites only then need "man-rating"<br /><br />man-rate an existing rocket may need time and money but not so much time and money like build a new rocket before<br /><br />also, great part of CEV crews' safety will be in LAS "hands", so, a reliable LAS mean a reliable launch for crew<br /><br />about man-rating costs... posts with info and links welcome here<br />

 

[gaetanomarano]

<br />not impossible to say... the liquid booster don't need to be a rocket "adapted" to Shuttles but a rocket "tailored" for Shuttles... and a (tailored) liquid booster can't have any "fire leakage" between "rings"<br />

 

[najab]

><i>...many american and non-american rocket can launch 12 tons (or more) in orbit ...</i><p>Examples, please.</p>

 

[najab]

Yes, it is impossible to say if a booster failure at T+73s would or would not be fatal - since it would be a completely different vehicle with a completely different flight profile. That was the question that SpaceKiwi was asking.

 

[gaetanomarano]

<br />I refer to the TRUE problem of Challenger disaster... "fire leakage between SRB's wings" ...this problem CAN'T happen with a liquid booster... of course, a liquid booster may have its own problems... and we can't exactly know them without real experience

 

[gaetanomarano]

<br />Ariane5, TitanIV, Soyuz/Shenzhou launchers (and other mid-rocket) with extra (or bigger) boosters... I don't think it is a problem... also because, IN PARALLEL with the CEV design years, will be available the next generation of rockets with increased payload capabilities... NASA certainly can have now full info about them (classified for common people) and make the right choice... probably NASA don't need to resize the CEV to 12 tons but only use one of the new (to-day classified) next generation rockets to launch its six-seats CEV without spend time and money to develop a new (liquid or solid) rocket... with 3+ years and $10+ billion saved!<br /><br />about a possible design of an "ideal" 12-tons-CEV rocket... I've an idea... when I will have the time to complete it (with as much possible precise specs) I will publish it on my website (and post a link here)<br />

 

[mlorrey]

gaetano, any liquid booster that uses SRBs to boost its cargo (and you know they will do it, just look at every heavy launcher out there) will run the risk of a ring blowout destroying the launcher, but the weak point here is the liquid tanks, not the SRBs. An SRB based launcher would have no liquid tanks to blow up, so it is inherently safer, it can launch with an o-ring leak without danger, and given the increased loads of stacking a cargo atop the SRB, the segment clamps will likely be a lot stronger than the STS SRB segment clamps.

 

[gaetanomarano]

<br />the discussion around SRB's rings leakage was about Challenger disaster not CLV... with CLV a similar leakage can't make any tank to explode

 

[haywood]

Ah Gaetano, NASA solved the SRB segment rings problem amost 20 years ago. Why are you bringing this up now?<br />I am constantly amazed at the crap you bring up right out of the blue.<br /><br />And, by the way, it wasn't the "leakage" that made the ET explode.<br />The flame leakage burned thru one of the lower attachment struts causing the SRB to rotate into the ET, thereby causing it to explode.<br /><br />

 

[drwayne]

Note also that the Challenger joint failure started in part from the rocking of the stack when the SSMEs start. That effect at least is a property of the shuttle stack, and should not occur in a single stick configuration.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>