LIVE: SpaceX - Falcon I (Mk.II) NET March 20 (Attempt 2)

[meiza]

Great! SpaceX is doing a lot of good by talking to the media like this.
So they throttle down Merlin before shutdown and the pitch moment should be smaller, and they'll also redesign the baffles and perhaps tweak control software.

I wonder if the second stage was coning and rolling a lot, or even tumbling after the 5 min public video loss, but kept thrusting? That'd be some cool video to see...

[eeergo]

What are these 'sloshing baffles' like?

Talking about the 2nd stage engine burn lasting to L+7:30... how was it able to do that considering the crazy spinning it was under, just before the end of the YouTube video? From my -small- experience with Orbiter, when the spacecraft is moving like that, it's nearly impossible to regain control... am I missing something?

[Avron]

eeergo - 25/3/2007  10:38 AM

What are these 'sloshing baffles' like?

Talking about the 2nd stage engine burn lasting to L+7:30... how was it able to do that considering the crazy spinning it was under, just before the end of the YouTube video? From my -small- experience with Orbiter, when the spacecraft is moving like that, it's nearly impossible to regain control... am I missing something?

See Jon's post one page back.. #123932

I would expect the conning of the second stage to transition into a rotational motion, what I dont get is the shutdown of the second stage after another  few mins of burn in this conning/rotational motion, something must have dampered out a bit to be able to keep going... love to see the rest of that video to ring sep..

Very nice article, and great feedback from Spacex.. even if the Roll looked like Pitch/Yaw to me at stage sep.

Now to get our hands on that full video..

[Avron]

Thomas ESA - 25/3/2007  9:04 AM

I'm impressed by Mr Musk.

A most amazing man, he does not need to do this SpaceX thing, he has more than enough cash in the bank, but he selects to spend hiswealth and energy in moving us all forward in the launch game.. one man an a dream.. we need more like Mr Musk in this world.. Not bad for an African...

Great news all around..   Go Spacex

[eeergo]

I had skipped page 48 in getting up to date Thanks Avron!

[Nate_Trost]

Neat. Hopefully they will release the full video.

I have to say, however, it seems a little nuts to not plan a F9 demo launch at this point. Unless that Q2 2008 "US Government" flight *is* basically a demo flight for someone like the NRO.

[landofgrey]

aero313 - 21/3/2007  8:44 AM

landofgrey - 21/3/2007  2:48 AM

Orbit or not, today history was made. NO entrepreneurial space launch company has ever been able to even attempt a launch to orbit, not in the last 30 years. so SpaceX continues to blaze the way,

What part of "Pegasus was completely developed with private investment" was not clear.  Same goes for Taurus and Lockheed Athena.

Taurus used previously developed components. Athena was mostly built out of already developed components and I won't consider Lockheed to be entrepreneurial, nor was Orbital at the time they developed the Taurus.

Also, I have never considered Orbital to be in the same class of entrepreneurial startups. That's not a dig on them, but rather merely a statement that the way the company was founded, and succeeded, was done in a different manner than the dozens of startups that have come and gone over the past 30 years. In fact, Orbital did things right in the end and most others did not. It was more along the lines of the way traditional aerospace/aeronautical companies are born and grow. Not to mention eventually a lot of outside investment. I wasn't ignorning them, forgetting about them or slighting them.

But, if a sensitive nerve has been touched over a comment that is really of no consequence, then I will amend and say "none in the last 17 years and only the second small U.S. entrepreneurial space company ever to attempt a launch to orbit". (I won't mention SSI as they'd already been bought out by EER at the time Conestoga disintegrated over the Atlantic).

I can't stand nitpicking or anal-retentiveness but I guess we're all like that. I'm as guilty as anyone. BTW, the book Silicon Sky about OrbImage is one of my favorite business case studies.

[landofgrey]

aero313 - 21/3/2007  2:04 PM
I just have a problem with people on this site and others treating Elon Musk like the second coming of Robert Goddard.

I wouldn't disagree, but I think (hope?) that it's just a lot of enthusiasm and hoping that a new company, and Elon, finally succeeds at bringing a new launch system to market after years and years of failed ventures littering history. I just want them, and all the other companies, to succeed. The industry needs it.

[landofgrey]

Arto - 21/3/2007  6:46 AM
I wonder at all this hostility. It was a test/demonstration flight, after all. From http://www.nasaspaceflight.com/content/?cid=5051:

The Falcon I will be carrying Demosat (LCT2 / AFSS), which is a demonstration for DARPA (Defense Advanced Research Projects Agency), along with two small experiments for NASA.

The primary DARPA objective for this mission is to gather flight data on the Falcon 1 launch vehicle and supporting systems. A secondary objective is to separate a payload into LEO, to place the second stage into the planned final orbit, and demonstratiing AFSS using the LCT2 for telemetering data back to Kwajalein and to Wallops Flight Facility.

In light of the mission objectives, it's a bit harsh to try and spin this as an "utter" failure.

In 1957, NRL and Martin Corp. emphasized that the TV-3 Vanguard launch was going to be a test launch, the first test launch involving all rocket systems. They pointedly laid out the fact that a distant secondary objective was to orbit a satellite, but that they did not expect it to happen. Directly to the press, they stated that it was only a test launch of the rocket that might end up orbiting a satellite. So... on Dec. 6, 1957 when Vanguard blew up, of course everyone forgot about NRL and Martin's admonitions and painted it as a total disaster, failure and tragedy and villified Vanguard and everyone involved... and completely ignored it was just a test launch, not a satellite launch. Sometimes it seems history repeats.

[kevin-rf]

SpaceX's site does not say much about the Merlin 'design' other than 'Propellant is fed via a single shaft, dual impeller turbo-pump operating on a gas generator cycle.' A look at the photo's and 3D cad drawings they provide show that turbo-pump rotational axis is offset from and parallel to the vehicles center line. For the greater vehicle rotational rate from the Merlin does this mean that they did not take into account the rotational momentum imparted to the vehicle when the turbine stops spinning? The turbine is also offset, could that caused the tip up? Where they planning on it spinning down gracefully and it actually seized?

I wonder what they are going to do when they spin down 9 Merlins on the falcon 9? (I know this is a crap idea but have 4 spin clockwise, 5 spin counter clockwise. It would require two different engine designs).

[Avron]

JIS - 25/3/2007  3:22 AM

JonSBerndt - 23/3/2007  6:23 PM

The point remains: was there a pitch or yaw acceleration at sep, and if so, what caused it?

Jon

Merlin

Look again, Jon is correct, there is acceleration in Yaw after 1st stage contact, and that is not what is expected with contact, if anything it would stop, reduce or impart an opposite yaw to the 2nd stage, but no it keeps on going until the 2nd stage corrects.. and that cannot be Merlin as the first stage has already dropped away.

[kevin-rf]

Avron - 25/3/2007  8:40 PM

JIS - 25/3/2007  3:22 AM

JonSBerndt - 23/3/2007  6:23 PM

The point remains: was there a pitch or yaw acceleration at sep, and if so, what caused it?

Jon

Merlin

Look again, Jon is correct, there is acceleration in Yaw after 1st stage contact, and that is not what is expected with contact, if anything it would stop, reduce or impart an opposite yaw to the 2nd stage, but no it keeps on going until the 2nd stage corrects.. and that cannot be Merlin as the first stage has already dropped away.

If the turbine is imparting roll as it spins down I could see it causing the nose of the first stage to draw wide circles. The rotational torque being imparted is off axis and at the back end of the rocket (Where most of the mass of the empty stage is). The turbine as it spins down wants to spin the rocket around it and the stage wobbled like a top as it was being grabbed by the turbine. You kinda see the wide circles in the video.

Honestly if this is due to the off axis turbine spinning down, it could doom the stage. They need to either have something counter it on the first stage or keep the turbine spinning through staging.

[Seattle Dave]

When is their next launch? Will they have enough time to make the baffle mod into the LOX tank before their next launch?

Anyone got images of baffles inside a tank?

[yinzer]

I think their next launch is whenever the rocket is ready, so by definition they will have time to extend baffles in the LOX tank if that is what is needed.

As for actual photos of baffles, I don't see many out there, but there are plenty of drawings, at places like here.  The concept is simple, a plate with a bunch of holes in it, to cause turbulence and resistance to flow.

[Antares]

meiza - 25/3/2007  10:38 AM
So they throttle down Merlin before shutdown and the pitch moment should be smaller

I just read that, shutting down from a lower G level.  I've never read anywhere that the Merlin can throttle.  Does anyone have info that it can?

[pippin]

kevin-rf - 25/3/2007  1:52 AM

I wonder what they are going to do when they spin down 9 Merlins on the falcon 9? (I know this is a crap idea but have 4 spin clockwise, 5 spin counter clockwise. It would require two different engine designs).

Less of an issue. Since the Engines are on both sides of the center they would counter-act. You might want to rotate them to compensate for the off-center alignment, but that should be possible with 9 engines (givent thermal compatibility).

[Jim]

pippin - 26/3/2007  9:09 AM

kevin-rf - 25/3/2007  1:52 AM

I wonder what they are going to do when they spin down 9 Merlins on the falcon 9? (I know this is a crap idea but have 4 spin clockwise, 5 spin counter clockwise. It would require two different engine designs).

Less of an issue. Since the Engines are on both sides of the center they would counter-act. You might want to rotate them to compensate for the off-center alignment, but that should be possible with 9 engines (givent thermal compatibility).

They would also shutdown in a staggered fashion

[JonSBerndt]

pippin - 26/3/2007  8:09 AM
Less of an issue. Since the Engines are on both sides of the center they would counter-act.

Not true. A positive torque is a positive torque. If the turbine spinning is providing an opposite torque to the rocket frame, it doesn't matter where it is placed. Or, am I misunderstanding your statement?

Jon

[JonSBerndt]

kevin-rf - 25/3/2007  10:01 PM
Honestly if this is due to the off axis turbine spinning down, it could doom the stage. They need to either have something counter it on the first stage or keep the turbine spinning through staging.

I believe that it was stated that the nozzle recontact was due to the unexpectedly high body pitch/yaw rate at staging (which, in turn, was due to a thrust tailoff issue on the first stage, IIRC). When the vehicle separated, each body (due to conservation of angular momentum) continued rotating about its own CG. The end result - as we saw - was the the stage 2 nozzle moving "west" and the top of stage 1 moving "east". The body rates need to be nulled out prior to separation.

Jon

[pippin]

JonSBerndt - 25/3/2007  4:17 PM

pippin - 26/3/2007  8:09 AM
Less of an issue. Since the Engines are on both sides of the center they would counter-act.

Not true. A positive torque is a positive torque. If the turbine spinning is providing an opposite torque to the rocket frame, it doesn't matter where it is placed. Or, am I misunderstanding your statement?

Jon

Partly.

Of Course, the positive torque would add up around the axis of the LV, so you get a lot of roll moment.
But the problem here, as I understand it, was that the roll was induced off the roll axis an therefore also induced a pitch/yaw moment. That part can be compensated for by properly placing identically rotating shafts (still all of them off axis) around the axis of the LV. You probably still get a lot of roll but that may be less of an issue if you just wait with stage separation until all engines are out and you can compensate for the roll later if you re-gain roll control. Or you can compensate for it by providing active compensation during the shutdown phase.