SpaceX: Falcon 1 OPERATIONAL

docm · Mar 28, 2007

They're sounding confident that they have a handle on their gremlins; Article.... <blockquote>In reply to:<hr />SpaceX Declares Falcon 1 Rocket Operational Despite Less than Perfect Test WASHINGTON — Space Exploration Technologies (SpaceX) has declared its Falcon 1 rocket ready to begin launching satellites in September despite a premature engine shut down that prevented the booster from reaching orbit during a second demonstration flight last week. “Having had several days to examine the data, the second test launch of Falcon 1 is looking increasingly positive,” SpaceX chief Elon Musk wrote in a Tuesday update posted on the El Segundo, Calif.-based company’s Web site. ”Post flight review of telemetry has verified that oscillation of the second stage late in the mission is the only thing that stopped Falcon 1 from reaching full orbital velocity. The second stage was otherwise functioning well and even deployed the satellite mass simulator ring at the end of flight!” SpaceX launched the two-stage Falcon 1 rocket March 20 from its Omelek Island launch site on the Pacific Ocean, but the rocket failed to reach its intended 425-mile (685-kilometer) orbit due to a roll control glitch. Musk said that no further demonstration flights are needed before the Falcon 1 is entrusted with the Pentagon’s experimental TacSat-1 remote sensing satellite. “This confirms the end of the test phase for Falcon 1 and the beginning of the operational phase,” he wrote. “The next Falcon 1 flight will carry the TacSat-1 satellite for the U.S. Navy, with a launch window that begins in September, followed by Razaksat for the Malaysian Space Agency in November. Beyond that, we have another nine missions on manifest for [Falcon 1] and [Falcon 9].” /><hr /></blockquote> <div class="Discussion_UserSignature"> </div>

rocketman5000 · Mar 28, 2007

Two things, 1. I hope they are right. 2. I hope Falcon 9 doesn't have the same problems

trailrider · Mar 28, 2007

This also brings up the questions (1) Why didn't they include slosh baffles in the first place? Apparently they didn't think they needed one; (2) what weight penalty will they incur by adding the slosh baffles? The other thing I don't quite have all the details on is what imparted the high roll rate? Was it contact between the Stage 1/ interstage and the Stage 2 nozzle, or was the vehicle rolling prior to separation? Depending on the design of the 1st stage engine/nozzle it could create a rolling moment. This may be a problem for the Ares I's first stage as solid rockets do tend to roll depending on the way the nozzle is constructed. My understanding is that the Ares I will have some type of ballistic gas generator type roll control. Ad Luna! Ad Ares! Ad Astra!

docm · Mar 28, 2007

NO BAFFLES!! <img src="/images/icons/shocked.gif" /> That was my first question when it was shown oscillating. WTH were they thinking? I'd put them in just as a CYA <img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> </div>

rocketman5000 · Mar 28, 2007

from what it sounded like it was probably combustion instabilities as the engine shut down. As the chamber loses pressure the nozzle will become over expanded. If it doesn't have a good enough pressure ratio to sustain the correct flow you will get normal shocks inside the nozzle, followed by flow seperation.

MeteorWayne · Mar 28, 2007

That was the impression I got reading carefully through their analysis. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

dreada5 · Mar 28, 2007

Elon's comments about negative media reports just goes to show he closely he/his people follow the press stories etc.

nwade · Mar 28, 2007

Did I miss something? I was under the impression from earlier comments that the Falcon 2nd stage *did* have baffles - they just weren't sufficient for what happened on this launch (the Apollo missions went through several different baffle designs on different launches, BTW). If you read the whole report on the SpaceX.com website, it sounds like the engine shutdown of the 1st stage caused some movement at a higher rate than expected. That movement is what caused the contact between the two stages. The recovery from both the original movement (started before stage sep) AND the impact of the two stages is what began the oscillations. The tank slosh and control system reaction to all of the above is what perpetuated it into a divergent-type cycle. ...At least that's the way I read it. See the SpaceX website for the full details. --Noel

Swampcat · Mar 28, 2007

"...At least that's the way I read it." I received my e-mailed update from Space-X this afternoon, which is essentially the same as their online update...without the pictures. From my reading, that's pretty much what happened...Merlin engine shutdown caused some transients which imparted a greater than expected roll. At stage separation, this rolling motion caused the upper stage to impact the upper stage nozzle with enough force to initiate the excessive sloshing. Although the upper stage TVC was able to handle the impact of the first stage and get the vehicle back to the proper attitude, the sloshing eventually overcame the system. As far as the slosh baffles are concerned, they may not be needed (read the part from the update that says " the Atlas-Centaur tank has no baffles"), but Mr. Musk seems to believe that having them would be better than the risk of an operational flight having this same problem. Perhaps after they get the first stage shutdown problem solved they'll reconsider. We'll see. I'd like to add my appreciation for SpaceX's openess and looking forward to their first operational flight in September. <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>

JonClarke · Mar 28, 2007

That's very encouraging. I assume the mass simulator is in orbit, just not the intended one? Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

MeteorWayne · Mar 28, 2007

I believe it was well below orbital velocity (~ 75% of required), and therefore didn't even make an orbit, if I read it right. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

spacester · Mar 28, 2007

The TVC was expected to be able to damp out the sloshing, but the sloshing was too severe, due to the pitch/yaw of the first stage at separation being 5 times grater than expected, which caused it to smack the second stage and start the sloshing. <div class="Discussion_UserSignature"> </div>

Swampcat · Mar 28, 2007

"I believe it was well below orbital velocity..., and therefore didn't even make an orbit, if I read it right." That's correct. Mr. Musk said the "[A]ctual final velocity was 5.1 km/s or 11,000 mph, whereas 7.5 km/s or 17,000 mph is needed for orbit. Altitude was confirmed to be 289 km or 180 miles, which is certainly enough for orbit and is about where the Space Shuttle enters its initial parking orbit." <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>

docm · Mar 29, 2007

<blockquote>In reply to:<hr />we believe that the slosh issue can be dealt with in short order by adding baffles to our 2nd stage LOX tank and adjusting the control logic.p><hr /></blockquote> To me the term "adding baffles" indicates a previous absence of same. If they meant "adding additional baffles" then that's what they should have said. <blockquote>In reply to:<hr />Either approach separately would do the trick (eg. the Atlas-Centaur tank has no baffles)p><hr /></blockquote> And this part of the quote just confirms my first impression: NO BAFFLES. Otherwise why even mention Atlas-Centaur? <div class="Discussion_UserSignature"> </div>

scottb50 · Mar 29, 2007

I think a slightly heavier tank with a gas operated floating piston would make more sense, eliminate turbo-pumps altogether. Liquid Helium to cool the engines and nozzles vents to the tank as a high pressure gas to power the piston. With a generous prelaunch pressurization the amount of Helium required would be fairly limited and could be recovered for future use. The engine could be extremely simple, a standard burner section with different nozzles and operating pressures for various Stages or Tugs. Simple and economical. <div class="Discussion_UserSignature"> </div>

no_way · Mar 29, 2007

<blockquote>In reply to:<hr />I believe it was well below orbital velocity (~ 75% of required)<hr /></blockquote> Except that the linear % of speed does not give the right picture here, because as the stage gets lighter, it accelerates faster.

rocketman5000 · Mar 29, 2007

Now you are talking about an completely different machine. Not really feasible at this point in the game, and it adds countless additional kilograms to the rocket.

holmec · Mar 29, 2007

Not to mention that a "floating piston" requires gravity..... <div class="Discussion_UserSignature"> "SCE to AUX" - John Aaron, curiosity pays off </div>

holmec · Mar 29, 2007

Yeah, he's getting a little defensive....But that's what you get in an industry where its been established "Failure is not an option!" in the minds of the media. <div class="Discussion_UserSignature"> "SCE to AUX" - John Aaron, curiosity pays off </div>

holmec · Mar 29, 2007

If Mr Musk is right, then he will be vindicated in the next launch. <div class="Discussion_UserSignature"> "SCE to AUX" - John Aaron, curiosity pays off </div>

dreada5 · Mar 29, 2007

<blockquote>In reply to:<hr />Yeah, he's getting a little defensive....<hr /></blockquote> Anyway, its all good. I like the way anytime folks critiques Falcon, he just compares where SpaceX is to where Boeing/LockMart were at that same stage of development and hey, suddenly things don't look so bad! <img src="/images/icons/smile.gif" /> He just loves sizing up to Boeing/LockMart. I think he's got it in for them big-time, is keen to level the playing field and blatantly start taking chunks of their market share from right beneath their noses!

jimfromnsf · Mar 29, 2007

Not so fast. He hasn't flown anything in the Delta or Atlas market yets. He can't size up to Boeing and LM in the 50's because he has all the advantages of the work since then. He has to size up to the EELV program, which hasn't had a single core LV fail at this time. spacex has done some good demos but has yet to do anything that can be used to trash talk

MeteorWayne · Mar 29, 2007

Hey, at least they are making progress, and telling us about the process. Both can't be said about any of the other contenders. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

scottb50 · Mar 29, 2007

Not to mention that a "floating piston" requires gravity..... No it doesn't, it needs pressure, pre-charged for start-up the Helium would takeover and force all the propellant out. By using composites and eliminating the turbomachinery you might even save some weight. <div class="Discussion_UserSignature"> </div>

scottb50 · Mar 29, 2007

That would require greatly heavier fuel and Oxid. tanks !>> I thought that was what I said. Upper stages use Helium to pressurize the propellant tanks and are pressure feed. The only difference with my idea is you heat the Helium up to increase the pressure for a first stage engine. <div class="Discussion_UserSignature"> </div>

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