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#11
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Today's Antares launch just failed
On Wednesday, October 29, 2014 8:24:50 PM UTC-4, JF Mezei wrote:
NASA released a simgle image, aereal view of the launch pad. http://www.nasa.gov/press/2014/octob.../#.VFF_5ee6BoU There appears to be very little debris. Is this because NASA deliberatly chose to release an image that has the real debris out of camera angle ? Great picture. I disagree. There seems to be a lot of debris, it's just that none of it is very big. Given the magnitude of the explosion, nor would I expect any of it to be. Check out the "bullet holes" in the water tower tank. (Can't really see if there was total penetration but something impacted there). They're going to be pulling fragments out of this site for awhile. You can also see what appears to be an impact crater just to the seaward side of the LC. *sigh* From the twisted metal perspective I suppose it could have been worse. Also don't forget of a fair amount of debris is no doubt hidden underwater. Some spectacular corkscrewing in the exploding wreckage as I recall. It's experiences like this (not scrubs) that *really* test the professionalism of your team, and put the "steely-eyed" into the missile-men and missile-women. Pick-up, clean-up, fix, test, and try again... Ad Astra Orbital... Dave |
#12
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Today's Antares launch just failed
"JF Mezei" wrote in message
eb.com... On 14-10-29 23:03, Greg (Strider) Moore wrote: Yeah. This is one of the lessons I think we CAN take from the shuttle program. Reusability at the very least lets you gain experience with the same engines and equipment. What if disposable engines would recuperated and analysed post flight ? Wouldn't that also give some valuable "how they behave in real life" to help fine tune the design ? Yes and no. First what is a "disposable engine"? Think a bit about that before replying. What makes an engine disposable? Also, it won't eliminate infant mortality issues. I believe, but don't have a cite handy, when they finally started reducing the amount of teardowns they did on the SSMEs, reliability went up. (since few places to introduce issues) And also, how do you RECOVER said engine in a condition that it's fit to be analyzed? And if you're going through that much trouble, why's it not re-usable again? -- Greg D. Moore http://greenmountainsoftware.wordpress.com/ CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net |
#13
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Today's Antares launch just failed
"JF Mezei" wrote in message
eb.com... On 14-10-30 18:59, Greg (Strider) Moore wrote: You completely avoided the most important question. What defines a "disposable" engine and why? That's a very important question. Also, it won't eliminate infant mortality issues. However, the "disposable" engines are tested prior to launch. NASA and Obital repeated this many times that the particular engine on this flight had been fully tested at Stennis prior to being accepted. If those engines are tested properly before lauch ( and I believe test fired at the pad too, but obviously not to full power), shouldn't that eliminate infant mortality ? I'm not sure about that. That's pretty rare (and as for obviously not to full power, I don't believe the NK-33 is throttable, so that basically means 0% or 100% power nothing in between.) Is it possible that those engines are rated for only x minutes of operation, and testing at Stennis uses up those minutes which causes some wear in the engine, some at launch time, the engines are already beyond designed lifetime ? So you're claiming the engineers can't do basic math and determine that testing the engines exceeded their lifetime? (Perhaps the Soviets tested them far less (or not at all) before flight, yielding more reliable launches ? Right, because the N-1 was such a successful launcher. Considering that this design had never flown to space successfully before Orbital did so on their first Antares flight, I don't think one can make that case. On the other hand, if after testing at Stennis, the engines are taken apart and inspected, then all bets are off. I believe, but don't have a cite handy, when they finally started reducing the amount of teardowns they did on the SSMEs, reliability went up. (since few places to introduce issues) Yes, but this requires enough flights with full teardowns to obtain MTBF numbers that then allow you know know how often you need to check certain areas and replace certain parts due to wear. Recovering a disposable engine after a real flight might show that the engine was dangerously beyond wear limits so it would need to be redesigned more robustly, or that it was well within the limits. BTW, for rocket engines, what propells the turbopumps ? is there a turbine just outside the combustion chamnber (like on jet engines) that give the motor force to spin the turbopumps ? Or are they electric/hydraulic/whatever driven ? That varies on the engine. With the NK-33, preburners drive the pumps (and they use LOX to cool stuff which to the US is a bit unusual.) -- Greg D. Moore http://greenmountainsoftware.wordpress.com/ CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net |
#14
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Today's Antares launch just failed
"JF Mezei" wrote in message
eb.com... On 14-10-31 06:57, Greg (Strider) Moore wrote: What defines a "disposable" engine and why? One that they don't even bother recovering after flight (let alone re-use). You've defined DISPOSED engines, not disposable. The point I'm trying to get is that designing an engine to be disposable is somewhat stupid. You need to build an engine with a certain level of margins. You want to be able to do a test-fire, perhaps a pad abort. At some point the smart engineer will realize that making a disposable, but reliable engine doesn’t save you much in times of design costs or usage costs. We've got to stop thinking about "disposable" engines. I'm not sure about that. That's pretty rare (and as for obviously not to full power, I don't believe the NK-33 is throttable, so that basically means 0% or 100% power nothing in between.) During launch, I heard 108% just before the failure. Is it possible the Orbital modifications to all the control systems on those engines allow for throttling ? Possible, but unlikely. In general for a multi-stage rocket you don't gain much with the additional complexity. The SSME had it because it went from sea-level to orbit. Off the top of my head, the only other throttlable main stage engine I can think of is Merlin and that's only because they want to land the thing again. So you're claiming the engineers can't do basic math and determine that testing the engines exceeded their lifetime? Depends on how the lifetime is defined. Also, NASA may require the engines to spend X minutes running at Stennis, so Orbital signed the papers to qualify the engines for those X minutes + launch. And again, I'm sure OSC did the math on this. Do they **really** know what those engines were rated for when the Soviets built them ? I'm sure OSC knows what they've been told. And what the testing suggests. -- Greg D. Moore http://greenmountainsoftware.wordpress.com/ CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net |
#15
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Today's Antares launch just failed
"JF Mezei" wrote in message
eb.com... On 14-10-31 12:30, Greg (Strider) Moore wrote: At some point the smart engineer will realize that making a disposable, but reliable engine doesn’t save you much in times of design costs or usage costs. For the engines, you are probably correct. At the powers/thrust involved, any imperfection yields wear and tear that is fatal. Ah, but one would argue that any imperfections that are fatal will be so very early on in the program. However, the cost of recovering the engines may make the economics less attractive when you consider you can only re-use the engine a certain number of times, unless you get to something like an aircraft engine. And that's exactly the point. We have to start thinking about them like aircraft engines with extended meantimes between failure. Design for success, not failure. Anytime a launch is done near ocean, it means SALT WATER is involved in recovering the engines for first or second stage. And SALT WATER is bad! That is probably really ultimately the biggest single issue with recovery, not the design itself. At the end of the day, the Shuttle wasn't all that bad despite all the criticism. The Shuttle got a lot wrong, enough that it tends to overshadow what it got right. Frank Culbertson said that the failure costed them about $200 million bucks. I am pretty sure that if the SHuttle had been operated "commercially" instead of "by pork", they could have lowered the launch costs to about 300 million. Ultimately, two things killed the shuttle: Massive overhead Few flights And both drove each other. The per cost flight of a shuttle was about $300M. When you figure the price per pound, that's actually pretty damn good. BUT, the overhead costs were damn high. They made the mistake (well it wasn't a mistake, they knew what they were doing and had little choice given the state of the art and the budget) of not designing it from the start for the lowest possible turnaround. Examples: LFBB, would have almost certainly ended up cheaper than SRBs (if only to eliminate the requirement for two ships off-shore to recover the booster) but would have cost a LOT more to develop. Or work platforms and designing the orbiter itself for far easier serviceability. Planned early on, but cost and mass limited it. Of course they were huge on "mass to orbit overall". Musk is making the choice of "cost to orbit". If you can only fly 1/2 the payload but costs you .49 as much, you come out ahead. Or replace the OMS/RCS pods with a non-hypergolic. Cheaper to service, cost more up front, etc. So yes, we already know from what was built it could have been cheaper to fly. Fortunately, Musk and others are learning the right lessons (perhaps the most important one being design for cost up front). -- Greg D. Moore http://greenmountainsoftware.wordpress.com/ CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net |
#16
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Today's Antares launch just failed
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#17
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Today's Antares launch just failed
In article ,
says... Right, because the N-1 was such a successful launcher. Considering that this design had never flown to space successfully before Orbital did so on their first Antares flight, I don't think one can make that case. I've come to learn that one NK-33 was used successfully on the first stage of the Soyuz "light" test flight a few years ago. But, Russia has a plan to replace it with a more modern design derived from the RD-171, which itself has its roots all the way back to the NK-33 and the NK-15 (the engine used on the failed N-1 test flights). Soyuz 2-1v launches on Maiden Flight after long Road to the Launch Pad, December 28, 2013 http://www.spaceflight101.com/soyuz-...st-launch.html But Soyuz 2-1v flew later in 2013 than the Antares test flight, so Orbital Sciences was indeed the first to use the NK-33 on a launch vehicle successfully. Antares Rocket Aces First Test Flight, APR 21, 2013 http://news.discovery.com/space/priv...ntares-rocket- aces-first-test-flight-130421.htm I'd not kept up with the Soyuz "light" launcher because it always seemed it would never happen. The Russians seemed quite satisfied flying the more familiar Soyuz first stage that dates all the way back to the original Sputnik satellite launch. Still, Soyuz "light" has only been test flown once so far. Rumor has it that Orbital will switch to the same "modern" engine to be used on the Soyuz "light" for its Antares first stage. In my mind, that's the right way to go. The thought that they'd use large solids for a first stage does not sit well with me. I'd really like to see an end to large solids all together. They are quite unsuitable for any sort of reusable launch vehicle, so it is my feeling their days are numbered in the launch vehicle industry. Jeff -- "the perennial claim that hypersonic airbreathing propulsion would magically make space launch cheaper is nonsense -- LOX is much cheaper than advanced airbreathing engines, and so are the tanks to put it in and the extra thrust to carry it." - Henry Spencer |
#18
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Today's Antares launch just failed
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#19
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Today's Antares launch just failed
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#20
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Today's Antares launch just failed
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