Author Topic: SpaceX COTS Demo 1 Updates (Read 662486 times)

Antares · « **Reply #1360 on:** 01/05/2011 04:49 am »

Typically in terrestrial applications, "swiss cheesing" of metals is for air circulation (heat convection) and, in really high volume production where the holes can be recycled, weight and cost savings. In aerospace, it's for weight. The cost saved by recycling the shreds is secondary, though measurable if production throughput is sufficiently high.

mmeijeri · « **Reply #1361 on:** 01/05/2011 05:01 am »

What is the difference between "pitch kick" and "beginning gravity turn"? I thought it was the pitch kick that initiated the gravity turn.

mr. mark · « **Reply #1362 on:** 01/05/2011 05:04 am »

Slightly confused? In the first frame above the hoses are in full view. At the moment of seperation the hoses dissapear. Are the hoses part of the second stage engine assembly?

mmeijeri · « **Reply #1363 on:** 01/05/2011 05:15 am »

Yeah, I was confused by that too. It looks as if at first you are looking "down" from above the second stage engine, while in the second you are looking "up".

spacetraveler · « **Reply #1364 on:** 01/05/2011 05:15 am »

Quote from: tigerade on 01/05/2011 02:55 am

I like the new videos! Thanks for pointing them out. It's kinda funny though, COTS1 is still showing up as an "Upcoming Mission" on the SpaceX website. I wonder why they haven't updated that yet?

Whoever does their website is a little slow.

They still list the first F9 flight as happening in 2009.

mmeijeri · « **Reply #1365 on:** 01/05/2011 05:16 am »

Good to know that they restarted the second stage engine successfully this time, I had been wondering about that.

Lars_J · « **Reply #1366 on:** 01/05/2011 05:26 am »

Quote from: mr. mark on 01/05/2011 05:04 am

Slightly confused? In the first frame above the hoses are in full view. At the moment of seperation the hoses dissapear. Are the hoses part of the second stage engine assembly?

There appear to have been two cameras in the interstate. At the moment of separation the video switches from one to to the other.

Pedantic Twit · « **Reply #1367 on:** 01/05/2011 05:36 am »

Quote from: go4mars on 01/05/2011 03:02 am

What is the cheese grater in photos 2&3?

We seemed to have forgotten the photo of Marty and his tin snips. Some of what appears to be the same stuff is visible in the lower left.

hpras · « **Reply #1368 on:** 01/05/2011 05:42 am »

So, stage 2 reignites for a few seconds and pushes it into a different orbit. My question is if it is a planned orbit or just a whatever it gets into. After SECO, the stage just drifts, correct? Looks like there is appreciable roll at dragon separation and maybe a bit of pitch at SECO. I would expect a slow tumble then if it's not actively dampened. Is the stage even pointing in the right direction to be controllable for a reignition.

Otherwise, good job Spacex, really hope you can make some money at this.

Edit - Spellun..... at least some of it.

kkattula · « **Reply #1369 on:** 01/05/2011 05:48 am »

Quote from: Pedantic Twit on 01/05/2011 05:36 am

Quote from: go4mars on 01/05/2011 03:02 am
What is the cheese grater in photos 2&3?

We seemed to have forgotten the photo of Marty and his tin snips. Some of what appears to be the same stuff is visible in the lower left.

IIRC, the interstage is carbon fibre. My guess is they don't want to bolt anything directly to it, so they have bonded metal mounting plates to spread the loads, with holes to reduce the weight.

Hauerg · « **Reply #1370 on:** 01/05/2011 05:53 am »

Quote from: go4mars on 01/05/2011 03:10 am

2 other things:

1) At 2:30 to 2:50 (dragon separation) what are all the little chunks drifting around?

2) Observation: When they restart the upper stage, the nozzle does not look warped/rippled as some were speculating earlier.

I was one of the ripple-seers, but you are right, it looks ok at restart.
Seemed like a very smooth ride to orbit. Great shots from stage 1 at sep.

ugordan · « **Reply #1371 on:** 01/05/2011 08:06 am »

Quote from: Toner Soprano on 01/05/2011 12:21 am

It looks like SpaceX updated their video section. I don't remember seeing inside the interstage and ascent video from inside the Dragon.

So I was right that was the Dragon ascent video all along. Yay for me.

Hauerg · « **Reply #1372 on:** 01/05/2011 08:45 am »

Quote from: ugordan on 01/05/2011 08:06 am

Quote from: Toner Soprano on 01/05/2011 12:21 am
It looks like SpaceX updated their video section. I don't remember seeing inside the interstage and ascent video from inside the Dragon.

So I was right that was the Dragon ascent video all along. Yay for me.

That earlier was not the same sequence as this one.
On this new one the best is in the last few seconds: you only see reflections but one of the things it reflects is the look out of the opposing window. Great.

ugordan · « **Reply #1373 on:** 01/05/2011 08:48 am »

Quote from: corrodedNut on 01/05/2011 12:53 am

Yes indeed, looks like they got some data back from the "talon pod" after all.

Not necessarily. Recall that F9 has *two* live video downlink frequencies according to the User Guide. The footage from the first stage only shows one view at a time and does camera switching, just like 2nd stage footage which is webcast. I would guess this extra video was received live from the stage so this by itself wouldn't be an indication they recovered anything.

ugordan · « **Reply #1374 on:** 01/05/2011 08:49 am »

Quote from: Hauerg on 01/05/2011 08:45 am

Quote from: ugordan on 01/05/2011 08:06 am
Quote from: Toner Soprano on 01/05/2011 12:21 am
It looks like SpaceX updated their video section. I don't remember seeing inside the interstage and ascent video from inside the Dragon.

So I was right that was the Dragon ascent video all along. Yay for me.
That earlier was not the same sequence as this one.
On this new one the best is in the last few seconds: you only see reflections but one of the things it reflects is the look out of the opposing window. Great.

Yes it is, the two cirrus clouds visible are the same. Just the cropping and contrast/brightness was different.

Identical.

corrodedNut · « **Reply #1375 on:** 01/05/2011 11:33 am »

There's only one camera in the interstage, the other one is in the 1st stage engine compartment. The "hoses" are the merlin feedlines, (remember the "octopus": http://forum.nasaspaceflight.com/index.php?topic=17941.msg442587#msg442587 ) the views are from MECO1 and 2; note the recirculating exhaust. The camera switches back and forth between 1st stage engines and interstage, which may explain the "confusion".

corrodedNut · « **Reply #1376 on:** 01/05/2011 11:36 am »

Quote from: ugordan on 01/05/2011 08:06 am

So I was right that was the Dragon ascent video all along. Yay for me.

And I was right about the one-piece nose cap, yay for me too.

ugordan · « **Reply #1377 on:** 01/05/2011 11:53 am »

Quote from: corrodedNut on 01/05/2011 11:36 am

And I was right about the one-piece nose cap, yay for me too.

What's interesting about that is the stage attitude disturbance at nosecone jettison did suggest a one-piece separation as you say, but it indicated the cap swung over and ejected to the upper right side of the camera FOV and yet nothing obvious was seen there in the webcast. Now we know why.

Comga · « **Reply #1378 on:** 01/05/2011 02:56 pm »

Another aspect seen in the videos is the motion of the first stage after separation. As seen in each previous Falcon launch since the third, but more dramatically shown here, the second stage engine slides straight out of the interstage with no visible rotation. A second or two later, though, the first stage starts rotating.

Stage Separation is 2:57
Rotation starts ~3:02
2nd stage ingintion 3.04

From the perspective of the 2nd stage camera, the front end of the 1st stage, the interstage, seems to move sideways with the back end, the engines, seeming to continue moving straight.

Anyone have an idea what causes that rotation?

ugordan · « **Reply #1379 on:** 01/05/2011 03:29 pm »

I speculated a while back that that was done on purpose to induce a tumble to the first stage to aid reentry. I'm thinking it could have been some high pressure gas cartridge in the interstage to give the top of the stage a kick.

Alternatively, I suppose one of the pressurization relief vents could have opened, but it seems like a way too big of a kick for that and we'd see some vapor venting.