Ridin' "The Stick": Dangerous, Complex, Cancelled?

rsp1202 · Oct 7, 2005

So call me an alarmist, but has anyone other than Griffin crunched the numbers to see just how safe it is strapping humans to the end of an SRB for launching the CEV? Beyond the quoted specs of the crew maxing out at 3G's at liftoff, what other guarantees are there that anyone can function normally after being turned into a human glop of tapioca after a two-minute ride on top of one of those things? We've all seen videos of the shuttle crews being shaken like crazy with SRBs firing off to the sides; does using one SRB halve the problem, or is the vibration doubled by placing SRB directly underneath? The trajectory guys might be able to mitigate some of this; ATK might know of a way to pour the solid mix so that pogoing and shaking is minimized without compromising necessary flight path -- but what if they can't? How much computer modeling has been done, and how many test flights have to be flown before they're sure? And if we're getting government/contractor guarantees that the system works as advertised, what happens if they're wrong? Think FEMA. By then, no shuttle; no CEV. I see this as a potential roadblock and budget buster that needs an early resolution. Anyone know what the astronauts think?

vogon13 · Oct 7, 2005

I have no idea how to implement this, but I have always thought SRB's needed some type of bladder or accumulator device to dampen the pressure spikes of the combustion of the fuel. The 'apocryphal' filament wound SRB casing perhaps had enough 'give' to dampen the snap somewhat? <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

nacnud · Oct 7, 2005

The bouncing around should be halved, and there risk is much smaller than the STS due to the launch escape mechanism. If you're frightened of SRBs then you should be happy with this system over the STS, half as many SRBs to go wrong.

SpaceKiwi · Oct 7, 2005

I definitely no rocket scientist, but I think you can take it as read that the system will work as advertised. Griffin would not have announced this solution without being satisfied that it will work, to a very high degree of confidence. With the presence of the escape system, it will be an entirely safer proposition in fact. I forget the figure he quoted, but it was by either a factor of 10 or 100 times safer. I don't think the Astronaut office will be too concerned about it at this stage, and probably not at all once NASA gets down the track a ways with some hardware built. It will be interesting to see how many unmanned test flights they undertake. I'd wager not that many. I do hope they will test the escape system in flight though, before they strap humans to the top. <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

vogon13 · Oct 7, 2005

I was thinking a balloon inside the combustion chamber made of the 'ballute' material from 2010 pressurized at like 2/3 of the expected chamber pressure. Having a 'compressable' volume inside the combustion chamber should stabilize things somewhat, gas bladders are used to 'dampen' 'spikey' hydraulic systems, I figured the combustion gases would be 'fluid' enough for the idea to work if the material science problem of the ballon material could be overcome. Another approach, IIRC, tried successfully on the hydraulic pumps of the Boeing 757 was to have a chamber in the system with a precisely machined ellipsoidal shape. The effect was to induce the pressure spikes to cancel out. This might be rather more tractable material science wise as such a device could be lined with a refractory material like the SRB nozzles are. Aeorspace payloads, human and electronic, don't like vibration, and if a lightweight reliable solution could be found, the failure rate of the whole system would improve. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

SpaceKiwi · Oct 7, 2005

Oh, excellent news SG, thanks. I think the 'stick' launcher is going to be a great little booster/spacecraft combination. I'm highly confident you guys are going to come up with a very elegant end-product there, both reliable and safe. It's the ET-derived Heavy Lifter that I think is going to present more headaches in the design and implementation. It looks like a hell of a technical challenge to radically redesign the ET for its new purpose, to my untrained eyes anyway. <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

SpaceKiwi · Oct 7, 2005

Hehe, yes SG, I guess you are quite right there! <img src="/images/icons/smile.gif" /> As all the Shuttle bashers and generally brains-deficient people seem to forget, going out and building those 'Rocket Planes' in the 70's/80's were an 'impossible mission' really. But you all went ahead, proved the doubters and nay-sayers wrong, and bloody built those amazing machines anyway! With all the engineering 'rocket-savvy' you have accumulated in designing, building, and operating Shuttle so well, along with the new materials and technology available now, getting the Heavy Lifter off the ground should be a relative 'walk in the park' really. <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

haywood · Oct 7, 2005

Quick question SG. How empty is the ET at ET-Sep? And does any propellant "leak" out at separation?

yevaud · Oct 7, 2005

True. After all, it's tried and true technology, with a long track record behind it. New materials and new techniques can only improve on it. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

scottb50 · Oct 7, 2005

Not like hanging a 100 ton winged spaceship on the side and feed propellant from the ET through flex lines and quick disconnects 17 inches in diameter. It works though. Hopefully the next generation will be much simpler. As long as a single SRB can put a usable payload into orbit and the feat can be repeated on a regular basis it sounds like a fairly good idea, for NASA. It does seem like Delta, Atlas, EAS the Russians, and even Titan, if it wasn't so rediculously expensive, could do the same thing. It's like introducing a 2010 model rocket, is NASA planning to compete for business, or intends on having it's own proprietary system, like now? Could anyone buy space on one of these launchers? The Russians, EAS beg for payloads, NASA just does it's thing. I think, if you asked Bush about the Space thing he would have absolutely no idea what you are talking about. It was a sound bite transmitted through the box that was prominently displayed in the Presidential debates. In one ear, out one mouth, unless he has two ear pieces, then he would have stereo, imagine Rove in one ear and Chaney in the other. No wonder! That would drive anyone crazier. <div class="Discussion_UserSignature"> </div>

rsp1202 · Oct 7, 2005

Okay, shuttle_guy, thanks for the feedback. If that's the case, then let's press to MECO.

lampblack · Oct 7, 2005

Being a naturally suspicious sort, I can't help but wonder if the Stick isn't really a sort of glorified fall-back measure. I mean: Elon Musk's folks are moving forward with the Falcon 9, a vehicle that will be able to lift 25 tons to orbit -- just like the Stick. Seems with everything the SpaceX folks are talking about, it might turn out a few years down the line to be easier (and cheaper) for NASA just to buy Falcon 9 flights instead of relying on the Stick. Just a hunch... <div class="Discussion_UserSignature"> Just tell the truth and let the chips fall... </div>

yevaud · Oct 7, 2005

You may well be right. One thing NASA seems to have in abundance is suspicion and doubts about anyone else's technology except their own, eg, from the short list of vendors they've dealt with for years. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

barrykirk · Oct 7, 2005

I would sure like to see a man riding a falcon 9 into orbit a couple of years before the stick is operational. I do think that Dr. Griffon said that he would use the private guys if possible.

lampblack · Oct 8, 2005

Dunno if it's a bad hunch or not. I posted that earlier message just an hour or so, actually, after reading the SpaceX update for June through September. Of course it's company propaganda, but it included these intriguing lines at the very end (within the context of discussing the Falcon 9's avionics): "The objective with the Falcon 9 avionics is triple redundancy with voting for the flight computer and inertial/GPS navigation system, and dual redundancy for the power system and telemetry, where voting isn't meaningful. Unlike Falcon 1, Falcon 9 is intended for manned flight one day and all critical systems have to function perfectly for potentially several days of occupied time." The added emphasis is mine. Clearly, they're planning to man-rate the beast. But of course (as SG suggests), it's still a paper rocket. And you may well be right in saying that the cost that goes with man-rating it will make the machine uncompetitive. I suppose we'll see. <div class="Discussion_UserSignature"> Just tell the truth and let the chips fall... </div>

crix · Oct 8, 2005

The intention is for the Falcon9 to be man rated. Elon has even directly said in a press release that ultimately his intentions are to colonize Mars! It may still all be paper but he's got a lot of infrastructure in place and I don't think he's gonna let up.

cuddlyrocket · Oct 8, 2005

"I can't help but wonder if the Stick isn't really a sort of glorified fall-back measure." Not surprising, as basically that's what Griffin has been saying. The stick is there to guarantee NASA (and therefore the US) manned access to LEO (including the ISS etc., but also to rendezvous with Moon-bound craft launched by the heavy lifter). But if the commercial sector can do it cheaper.......

shoogerbrugge · Oct 8, 2005

The SRB is one of the things in the STS system that actually works quite well. It would be foolish to ditch it and start with something new again. I first had my doubts about a sollid propellant booster, but with a proper escape system I think Riding the stick will be safer then sitting in a Orbiter

j05h · Oct 8, 2005

I'd like to see a 2006 test launch of a single SRB. This gives NASA an early indicator of how the CEV booster will fly, even if the '06 flight is a current, unmodified STS SRB. Just stick it on a pad and let it rip. i'd like to see the whole of the human-transport end of VSE/Constellation radically accelerated: early 2007 boilerplates, 2008 unmanned and 2009 manned flights. Fly early, fly often. Josh <div class="Discussion_UserSignature"> <div align="center">We need a first generation of pioneers. </div> </div>

rsp1202 · Oct 8, 2005

Fast-tracking testing would be great if they don't run into technical or budgetary snags. I think we'll also find pre-launch activity in prepping booster/CEV a bit more streamlined too. Upper stage LOX/LH tank fueling and pressurization issues will probably be pacing items as usual, but there will be one less liquid stage to worry about, no fuel cells aboard CEV to prime; I don't know about APU issues. Their computers won't be using Windows. Weather will always be a factor. In the oldest days, crews would bus to launch site and get strapped in and prepped four or more hours ahead of launch. I think shuttle crews arrived as little as two hours before zero hour. With CEV (hopefully), it might be crew arrives at pad . . . we have liftoff.

j05h · Oct 8, 2005

There must be a few already cast SRB cores, waiting for Shuttle flights - I think KSC should fix an old pad or change LC39 slightly to accomodate one. THey should fly an SRB next year to prove the concept. Just do it. On faster pre-launch - yes that would be nice, they should take note on Russian rocket and crew handling as well. Josh <div class="Discussion_UserSignature"> <div align="center">We need a first generation of pioneers. </div> </div>

darkenfast · Oct 8, 2005

Actually, there is a report by SAIC (for ATK), which evaluated the safety of the SRB/J2S version of the CEV concept and concluded that it is indeed very much safer than the current STS stack. Factors included: vertical stacking, SRB track record and halving the number of SRB's, and the use of an escape tower. The report is available on-line: "Reliability and Crew Safety Assessment for Solid Rocket Booster/J2S Based Launch Vehicle". Obviously, the engine for the upper stage has changed, but I think the numbers will essentially remain the same: in excess of the required 10-fold increase in safety over the STS.

SpaceKiwi · Oct 8, 2005

<blockquote>In reply to:<hr />The fins also cause issues for water impact since the would damage the aft skirt if that are not jettesoned.<hr /></blockquote> Oh, I wasn't aware they were going to continue the reusuable policy with the SRB part of the launcher. Is this definite? Allied to this, what is the likely flight profile going to be? I assume the basic principle is that you want to get to the closest point in LEO, without the additional constraint of needing to chase a space station? Is the pick-up point for the recovery ships going to be radically different to where it is now on Shuttle missions? <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

SpaceKiwi · Oct 8, 2005

<blockquote>In reply to:<hr />I do not understand the question, the SRB task is the same as it is on the Shuttle, get the CEV and upper stage off the pad and as high and as fast as possible in the same plane as the ISS.<hr /></blockquote> Sorry SG, I wasn't as clear as I might have been and I also failed to take into account the ISS aspect of CEV missions. I was thinking in terms of Moon missions where I assume you are ..... actually I haven't thought this through well at all. A Moon mission CEV will still have to hit a point in orbit to rendezvous with the Heavy Lifter payload, correct? I guess what I was trying to say is that a CEV not going to ISS might head off the pad in a slightly different easterly direction because it is not having to achieve the ISS's plane? Thereby requiring the recovery ships to head to a different spot in the Atlantic to pick up the spent boosters. <blockquote>In reply to:<hr />Yes, they will have to be further down range.<hr /></blockquote> Aside from all the difficulties you have already outlined, is the longer tow back to shore going to present problems from the extra time spent in the water? <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

vogon13 · Oct 8, 2005

Aha! I'm not the only one who's heard of them. IIRC, one was even test fired in Utah. Any of this sound familiar? <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

Ridin' "The Stick": Dangerous, Complex, Cancelled?

rsp1202

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