LIVE: SpaceX Falcon 9 (Flight 2) - COTS-1 - Launch Updates - December 8, 2010

[Robotbeat]

A couple months ago I used a terminal velocity calculator, all the published Dragon info I could dig up and some minor guesswork and came up with <300fps.

Sounds about right, if you assume a high(ish) drag coefficient (i.e. 1 or greater) and sea-level atmospheric density (1.29kg/m^3).

BTW, it's just a simple equation. Not necessary to use a specialized terminal velocity calculator, just google's calculator will do:
http://www.google.com/search?&q=sqrt(2*6000kg*g/(.88kg/m^3*((3.7m/2)^2*pi)*.6)

And the equation is from here (although it's not that hard to derive from just a basic understanding of Newtonian mechanics):
http://en.wikipedia.org/wiki/Terminal_velocity

(atmospheric density at 10,000 feet or a little more than 3km is around .88kg/m^3) ("m" is mass, "g" is acceleration due to gravity, or ~9.8m/s^2, "rho" (funny looking "p") is air density, which is about 1.29 kg/m^3, "A" is frontal area--which is equal to radius of Dragon squared times pi, and "Cd" is the drag coefficient, which is 1.15 for a short cylinder and .47 for a sphere... I think a capsule usually has a subsonic drag coefficient typically around .7 or more...)

[Antares]

Great now we have two threads hijacked by "How is Dragon going to land".

[Comga]

Agreed, Antares.  Can someone create a "Future Dragon Precison Landing" thread and leave this one for new about the COTS-1 flight?

[Lobo]

I am not sure about the specific configuration of the Dragon capsule, but at low supersonic/subsonic speeds capsules tend to be unstable, so at least a drogue chute is probably necessary. And the terminal speed under a drogue chute is certainly smaller than 755fps, so delta-v requirements in the end could be much smaller...
However, precision landing requirements will eat into these savings, depending on the accumulated errors until throttle up.
As for the trade-off btw parachute and fuel+thrusters mass fractions, I honestly have no idea.

Here's where I got the info on Soyuz.  I was referring to the parachute system in general when I taled about how much it reduces the speed.
The Soyuz drogue chutes slow from 755 fps to 262 fps.  The main chutes then slow to 24 fps.

http://www.nasa.gov/mission_pages/station/structure/elements/soyuz/landing.html

Dragon will probably be a little different, but I figure Soyuz reentry module was roughly similar in shape anyway to dragon, and so it's numbers could be used as a ballpark. 

So yea, drogues can be used to do a lot of the initial decelleration.  Or a hypercone or something inflatable to get it down to like 262 fps.  But I didn't hear Elon mention anything about that.  So that's why I was asking  Is there more to it than a 100% propulsive landing.  Because I got the -impression- he was talking about a 100% propulsive landing with parachutes as a backup.

Myself, I'm a big fan of mid air recovery with a large helicopter like a CH53, and using a parafoil rather than traditional ringslot parachutes so the capsule can be steered to a target recovery area like soft wing, and can be steered straight to make it easier for MAR.  Then you just land the capsule wherever you want.  Seems more reliable than landing thrusters, but maybe not.
Plus if your recover area was over the water, you could do a water landing if there was a problem with the MAR.  Just have divers already on board the helicopter.  Then can jump out, hook the capsule up to the CH53, and then get back in and head back to the SpaceX facility nice and easy. 

But the propulsive landing is an interesting concept if the amount of propellant needed for a LAS is adequate for propulsive steering and landing.

[Lobo]

Great now we have two threads hijacked by "How is Dragon going to land".

Doh!  Sorry!
Elon needs to quick ticking our curriosity with this stuff.  heheheh

[Ben the Space Brit]

@ Lobo,

I suspect that the propulsive, guided landing crew vehicle will be a completely new product.  Though it will likely use lots of Dragon-heritage technology, it will likely be radically different in several areas.  Personally, I'm expecting it to be something similar to the Delta Clipper/DC-X launched atop the Falcon-X core.

Crewed Dragon will be just a Dragon capsule with a reusable LAS that is also used at the moment of touch-down to slow its descent, as currently practiced by the Soyuz.  It won't have the 'land on a helipad' capability Musk talks about.

[kevin-rf]

Since this is the COTS-1 thread, any idea when SpaceX will update the Launch Manifest page and move this flight from Launch Manifest section to the Past Missions section?

http://www.spacex.com/launch_manifest.php

I am guessing soon after the chatter begins on NSF about it not being up to date

[mr. mark]

New recovery pics...

[Lars_J]

Yay! finally

I'm quite amazed that it is in such good condition. But better materials (since the Apollo era) explain that, I suppose.

EDIT: One interesting observation - The parachute compartment appears to be on the worst affected side (due to AoA at reentry), which leaves the hatch on the less affected side. I guess they trusted the covers of the parachute and its deployment.

[wjbarnett]

Looks a little worse for wear.

[mr. mark]

rectangles show nano satellites.

[corrodedNut]

Time to bump this thread, update:

http://www.spacex.com/updates.php

[arnezami]

I just wanted to point out that Elon Musk also talked about propulsive landing of the Dragon during the press conference** back in june 2010.

From around 37:54 into the conference he says:

And the other advantage of having the escape engines built into the Dragon spacecraft is that we can then, in the future, land propulsively using those same engines on land, just as the Eagle landed on the moon. I think that's really the right way to land a spaceship and that's what we intend to do.

So he has mentionded this before. Although the "helipad" and "lift off again" parts are new I guess.

** note: first minute of audio has a strange "sound-loop"

[Lars_J]

SpaceX has put up an initial highlight video of the F9 flight #2 / COTS1 mission:

http://www.spacex.com/multimedia/videos.php?id=57&cat=recent

Direct link to HD version: http://bitcast-a.bitgravity.com/spacex/2010/launches/falcon9_flight2_highlights_hd.mp4

And for those who missed it earlier, here's a close-up of Dragon after recovery from the water:

[ugordan]

SpaceX has put up an initial highlight video of the F9 flight #2 / COTS1 mission:

http://www.spacex.com/multimedia/videos.php?id=57&cat=recent

Looking at the video, it is obvious there was roll torque during liftoff again, perhaps as much as in the last flight, but the vehicle immediately countered and rolled back (unlike the last time where it just stopped the roll). Also, after stage sep it looks like the first stage induced a tumble on purpose, probably to aid recovery attempts.

[Ben the Space Brit]

Yay! finally

I'm quite amazed that it is in such good condition. But better materials (since the Apollo era) explain that, I suppose.

EDIT: One interesting observation - The parachute compartment appears to be on the worst affected side (due to AoA at reentry), which leaves the hatch on the less affected side. I guess they trusted the covers of the parachute and its deployment.

It will be interesting to see to what degree that blackening is cosmetic (combustion/ionisation products being deposited on the hull) and how much is actual thermal damage to the hull coating.  The answer to that question may be critical in determining whether Dragon can be used on multiple flights.

[stockman]

SpaceX has put up an initial highlight video of the F9 flight #2 / COTS1 mission:

http://www.spacex.com/multimedia/videos.php?id=57&cat=recent

Looking at the video, it is obvious there was roll torque during liftoff again, perhaps as much as in the last flight, but the vehicle immediately countered and rolled back (unlike the last time where it just stopped the roll). Also, after stage sep it looks like the first stage induced a tumble on purpose, probably to aid recovery attempts.

I have to respectfully disagree... Unless you are seeing something I am missing in this video I don't see any roll at all, certainly nothing compared to the almost 90 degree roll the first time.. Here are a series of pictures from engine start to just clearing the pad - the closeups in the top corner show the strongback in the top of the picture - if there was roll I would expect to see that change position in the picture but I can't detect any of that...

[ugordan]

Looking at the video, it is obvious there was roll torque during liftoff again, perhaps as much as in the last flight, but the vehicle immediately countered and rolled back (unlike the last time where it just stopped the roll). Also, after stage sep it looks like the first stage induced a tumble on purpose, probably to aid recovery attempts.

I have to respectfully disagree... Unless you are seeing something I am missing in this video I don't see any roll at launch, certainly nothing compared to the almost 90 degree roll the first time..

Look carefully at the erector and the right portion of the screen where the sprinklers are in the onboard video, when the vehicle is released. Also, note I specifically said roll torque, not roll. Don't confuse the two. The magnitude of the torque appeared very similar to F9-01. However, as I said the vehicle quickly took action and brought back the roll angle to "null". Looked like 10 degrees or less in roll excursion this time.

FWIW, this looks similar to what happened to the first Atlas III. It takes some time to fully characterize a new propulsion unit.

[stockman]

Looking at the video, it is obvious there was roll torque during liftoff again, perhaps as much as in the last flight, but the vehicle immediately countered and rolled back (unlike the last time where it just stopped the roll). Also, after stage sep it looks like the first stage induced a tumble on purpose, probably to aid recovery attempts.

I have to respectfully disagree... Unless you are seeing something I am missing in this video I don't see any roll at launch, certainly nothing compared to the almost 90 degree roll the first time..

Look carefully at the erector and the right portion of the screen where the sprinklers are in the onboard video, when the vehicle is released. Also, note I specifically said roll torque, not roll. Don't confuse the two. The magnitude of the torque appeared very similar to F9-01. However, as I said the vehicle quickly took action and brought back the roll angle to "null". Looked like 10 degrees or less in roll excursion this time.

FWIW, this looks similar to what happened to the first Atlas III. It takes some time to fully characterize a new propulsion unit.

Thanks.. I was thinking more about the Roll... my bad

[stockman]

looking at the video you can see some debris coming off and being blown away from the vicinity of the top of the strongback.. it lasts for a few seconds on the video. probably nothing important - just an observation

timestamp 00:25 to 00:37 on the video