SpaceX COTS Demo 1 Updates

[corrodedNut]

Quoting SPACEFLIGHT NOW -Falcon 9 launch timeline
"T+09:35 Dragon Separation
The Dragon capsule separates from the second stage, leaving behind its unpressurized trunk section, which contains secondary CubeSat payloads."

1- Do they mean the trunk will split from Dragon capsule right at Stage 2 sep. ?
In this case the rest of the in-space operations would be made without the trunk attached to Dragon !
2- If yes, how will they separate the trunk from the second stage once Dragon has gone away ?
3- How will they release the Cube Sats which are said to be in the trunk ?

AIUI:

1- Dragon will separate from the stack after 2nd stage shutdown.
2- The trunk will not separate from the 2nd stage.
3- Out of the open end of the trunk, apparently.

[robertross]

Correct, and maybe the heating delta is negligible, but remember that in vacuum the plume expands essentially to infinity, so the plume angle in your sketch will increase to basically vertical...

Good point. Darn vacuums...

Just wrap it in duct tape, should work fine 

The experts obviously know their thermal model well enough that if they say it's good to go, it's good to go.

[dbhyslop]

SpaceX said the nozzle extension improves the efficiency of its upper-stage Merlin vacuum engine but is not needed to execute the upcoming test flight. Launch time is scheduled between 9:03 a.m. and 12:22 p.m.

The wording of this paragraph in the Sentinal article implies to me that the nozzle is modular and the "extension" is meant to be removable.  If this is the case it is likely that Spacex had already done performance analyses and might have whatever software changes prepared ahead of time as a contingency, even before the discovery of the cracks.

Either way, I'd love to see how they get the thing out!

[Comga]

To my knowledge we have no evidence that SpaceX has done ANYTHING to the Niobium bell.  The statement was that from a performance standpoint they could meet mission requirements with a bell shorter than designed by many feet.   It didn't say that they HAD shortened it or even removed a small piece.

Frankly, I will be extremely surprised if they have done anything mechanical, even drilling a stress relief hole at the end of a crack.  The idea that they would take off the stiffening ring, modify the bell, modify the stiffening ring and reattach it or just discard it, and fly, even if they were to pull the rocket apart to expose the engine, is inconceivable.   

Jim excorciates them for not adhering to procedures, and with good reason, but this would be beyond improper. 

[billh]

Well, that would make more sense. I'm just astonished that they would make such a large, unplanned modification to the vehicle so quickly and then attempt a launch the next day. I'd be equally astonished that NASA would be comfortable with it.

[billh]

Well, Aviation Week reports they really are cutting off the bottom four feet:

http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/awx/2010/12/07/awx_12_07_2010_p0-274994.xml&headline=Falcon%209%20Readies%20For%20Wednesday%20Launch

[Kabloona]

SpaceX said the nozzle extension improves the efficiency of its upper-stage Merlin vacuum engine but is not needed to execute the upcoming test flight. Launch time is scheduled between 9:03 a.m. and 12:22 p.m.

The wording of this paragraph in the Sentinal article implies to me that the nozzle is modular and the "extension" is meant to be removable.  If this is the case it is likely that Spacex had already done performance analyses and might have whatever software changes prepared ahead of time as a contingency, even before the discovery of the cracks.

Either way, I'd love to see how they get the thing out!

That sounds like the best explanation...that they've done the thermal analysis, etc, without the extension, and thus have already designed and analyzed for the limiting case in which the nozzle extension length goes to zero...But that statement does beg the question, if the extension is "not needed", why not just take it off, and problem solved?

[jongoff]

Since I just checked, I thought I would share: Gibraltar is at 36N

Thanks for your info -

Launch Azimuth of 69.7° from KSC/Cape Canaveral corresponds to an orbit of 34.5° inclination.  This launch azimuth takes the Falcon-9/Dragon in a direction north of Bermuda and a subsequent over-flight track over Gibraltar and the Mediterranean makes sense.

Concerning Jay Barbree's question, Europe or Gibraltar are basically the same concerning his main point which was over-flight due to an event of an engine-out late in powered flight and the potential consequences of an uncontrolled descent.

It's still pretty weak sauce.  By the time in F9's flight where it's IIP (Instantaneous Impact Point--the point you would hit if you lost power at any given second) is crossing over any populate area, the IIP is going to be moving so fast that the actual odds of it hurting anyone are ridiculously low.  This isn't having your IIP passing over a densely populated are right as you're doing stage separation or something like that.  This is well into the 2nd stage of flight. 

Part of the launch license that SpaceX filed involves calculating E-sub-c (expected casualties).  That's the expected number of people to be hurt from a given flight.  FAA will not let you fly if your E-sub-c is greater than .00003 (30x10^-6). 

The odds of SpaceX's F9 failing at the exact instant it would take to actually hurt someone in Gibraltar or Northern Africa is vanishingly small, even if you assume a 100% probability of launch failure.  Let's do the math.  Say your IIP is going at say 5km/s (IIP typically moves faster than your actual ground track--at the split second before your perigee gets above ground, your IIP actually is effectively going infinitely fast), and your flight is say 600s long, and the populated area is 50km long with people standing hand in hand along the flight path that whole way so there's a 100% chance of fatalities if the thing fails during that timeframe, you're only looking at 1.6% chance (50km/5km/s=10s, 10s/600s =.016).

Yawn.

~Jon

[Note: the specific numbers like flight duration and IIP velocity and 50km populated area were all total guesstimates pulled out of certain nether regions]

[Antares]

SpaceX also gets less money per flight (and per KG of cargo) than Orbital in their CRS contract. This also tends to discredit your SpaceX favoratism theory. Incidentally, I am not saying that there is a favoratism towards Orbital. Orbital negotiated a better deal. That's all there is to it.

Not if their costs are higher.

[R.Simko]

This removing 4 ft. from the bell makes me feel like I'm reading a sci-fi novel and if the crew, that is stranded on Mars doesn't make an unorthodox emergency repair in a matter of hours, they will miss their launch window and never make it back home.


 I'll say one thing, SpaceX sure makes it exciting.   I can't wait for SpaceX the movie to come out.

[TheFallen]

Glad to see that this launch will be broadcast on NASA TV tomorrow.  No poor-quality streaming this time around... (Presumably)

[mr. mark]

Responding to reporters today about changes to the engine bell, Elon Musk had this to say about Falcon:
"She'll make point five past lightspeed. She may not look like much, but she's got it where it counts, kid. I've made a lot of special modifications myself".

[Antares]

Y'all take a lot of things on faith, assuming SpaceX has analyzed this case.

[Malderi]

Responding to reporters today about changes to the engine bell, Elon Musk had this to say about Falcon:
"She'll make point five past lightspeed. She may not look like much, but she's got it where it counts, kid. I've made a lot of special modifications myself".

The funny part is, I can actually imagine him saying something like that.

Of course, everyone thought they were crazy when they launched an hour after a pad abort. For everyone that thinks what they're doing is crazy, hold your opinions until after it (maybe) blows up. Let's just call it waiting for experimental data.

[joshcryer]

Glad to see that this launch will be broadcast on NASA TV tomorrow.  No poor-quality streaming this time around... (Presumably)

Probably point their range cameras down to the SpaceX pad like last time. Hopefully they'll bring some equipment down there and get some good close up footage.

I think they have fixed the web stream though, the test firing on the second day was very good.

I don't think they're crazy for cutting an unnecessary nozzle extension, I don't think they're crazy for launching after pad aborts, I don't think they're crazy for continuing to play with their system until they get a test fire.

I think they're just that good.

The whole system is designed to recover from aborts. The nozzle extension is there for efficiency boosting purposes. If they don't need it for completion of this Demo, why would they go and replace it? Cutting it just is a logical engineering choice when you have time considerations.

Go SpaceX.

[jimvela]

Let's just call it waiting for experimental data.

Experimenting with taxpayer dollars on a system that will be crucially needed for the future sustaining of the ISS...

[Kabloona]

Y'all take a lot of things on faith, assuming SpaceX has analyzed this case.

Well, we're all kind of hampered by lack of firsthand (or even much secondhand) information. All we know is what we're told:

Quote from Av Week: "To fix the problem, engineers cut off the bottom four feet of the nozzle, then ran analysis to assure the engine would perform as expected."

If they say they ran the analysis, I guess I have to choose whether to believe that, or not. Them being a lot smarter than me, I'm kinda believing they did.

[Jim_LAX]

Does anyone know if the Dragon will splashdown off the coast of Morro Bay California?  That is where the parachute drop test was done last month.  That would be a pleasant drive up the coast from Los Angeles to see the Dragon being towed back to shore.
Thanks in advance.

[Jim]

I think they're just that good.

Some serious koolade guzzling going on.

[robertross]

Does anyone know if the Dragon will splashdown off the coast of Morro Bay California?  That is where the parachute drop test was done last month.  That would be a pleasant drive up the coast from Los Angeles to see the Dragon being towed back to shore.
Thanks in advance.

From the press kit:
"After travelling approximately 50,000 miles, the
Dragon spacecraft is expected to land in the Pacific
Ocean about 500 miles off of the coast of Mexico
approximately three and a half hours after launch."