Author Topic: SpaceX: General Falcon and Dragon discussion (Thread 2)  (Read 616801 times)

Offline Art LeBrun

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1000 on: 01/16/2011 03:41 pm »

I remember Delta launches from Cape Canaveral of Tiros satellites  going to sun-synchronous orbits  in the mid 60's. But I think these went on a southerly azimuth and overflew the isthmus of Panama. Whether that would be allowed now I have no idea.


Proposed trajectories for Delta about 1965. I do not know if any of these were flown.
« Last Edit: 01/16/2011 04:11 pm by Art LeBrun »
1958 launch vehicle highlights: Vanguard TV-4 and Atlas 12B

Offline douglas100

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1001 on: 01/16/2011 06:38 pm »
Thanks for the map.

According to

http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1965-004A

and

http://www.n2yo.com/satellite/?s=978

it seems that Tiros 9 was indeed launched into a retrograde orbit from Cape Canaveral, dog legging on to an azimuth which overflew Cuba then Panama. Can you imagine that being allowed today?
« Last Edit: 01/16/2011 06:42 pm by douglas100 »
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Offline Jim

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1002 on: 01/16/2011 07:37 pm »
Thanks for the map.

According to

http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1965-004A

and

http://www.n2yo.com/satellite/?s=978

it seems that Tiros 9 was indeed launched into a retrograde orbit from Cape Canaveral, dog legging on to an azimuth which overflew Cuba then Panama. Can you imagine that being allowed today?


It was a 3 stage Delta and I believe most of the impulse of the 3rd stage was for plane change.

Offline ugordan

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Offline Robotbeat

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1004 on: 01/17/2011 04:52 pm »
CCDev2 video is back: http://www.spacex.com/multimedia/videos.php?id=58
BTW, there's a weird bug where the two audio channels when the speaker (Shotwell and Elon) in the corner are talking 180 degrees out of phase with each other, so when combined into a single channel (like for my laptop speaker), you can only hear some artifacts. It's easy to fix this by just adjusting the balance between left and right speakers to be slightly more for the left or right speakers (i.e. not centered) with "Volume Control" in Windows XP.
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Offline ugordan

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1005 on: 01/17/2011 04:55 pm »
Yeah, that goes back to the post-flight conference mic problem. One NASA youtube channel does have better audio (still inverted I think), but looks like SpaceX didn't use it.

Offline corrodedNut

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1006 on: 01/17/2011 05:18 pm »
And now there's a new update, relating to their CCDev2 proposal:

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

Offline docmordrid

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1007 on: 01/17/2011 07:10 pm »
Comparing the thruster shown in the video with a Draco they look different. There appears to be different proportions plus an apparently wider throat.  Could this be our first look at the LAS thruster? 
DM

Offline ugordan

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1008 on: 01/17/2011 07:15 pm »
It's Merlin 1a.

Offline Rhyshaelkan

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1009 on: 01/17/2011 07:16 pm »
Ick, if as Elon mentioned and the Dragon pulled 4-4.5 Gs. How much will the LAS pull? Granted they are automatic systems I am sure and a few seconds of blackout(or would that be red-out lying on your back that way?) will not be the end of the world :P
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Offline douglas100

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1010 on: 01/17/2011 07:23 pm »
I guess that if an abort were called at a high G part of the ascent, a shut down command would be sent to the main engine(s) before the LAS was triggered.
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Offline baldusi

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1011 on: 01/17/2011 07:27 pm »
Ick, if as Elon mentioned and the Dragon pulled 4-4.5 Gs. How much will the LAS pull? Granted they are automatic systems I am sure and a few seconds of blackout(or would that be red-out lying on your back that way?) will not be the end of the world :P
It's important to note that in eyeball in, 17G should be tolerable without blackout for a couple of minutes. If you need just a few seconds to clear the area, that should (hopefully) be enough. Specially with the resistance of Dragon's heat shield in your back. In fact, the worst part might be reentry, since you'd be eyeballs out.

Offline ugordan

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1012 on: 01/17/2011 07:29 pm »
Reentry would also be eyeballs-in. Deorbit would be eyeballs-out, but Draco thrust levels are so low this is a non-issue.

Offline baldusi

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1013 on: 01/17/2011 07:40 pm »
Reentry would also be eyeballs-in. Deorbit would be eyeballs-out, but Draco thrust levels are so low this is a non-issue.
Because the deceleration vector is negative to the advance direction, right?

Offline docmordrid

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1014 on: 01/17/2011 07:42 pm »
OK M1a - then here's another imagery question: why 2 sets of shock cones per quadrant? 8 LAS motors?
« Last Edit: 01/17/2011 07:43 pm by docmordrid »
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Offline ugordan

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1015 on: 01/17/2011 07:48 pm »
Reentry would also be eyeballs-in. Deorbit would be eyeballs-out, but Draco thrust levels are so low this is a non-issue.
Because the deceleration vector is negative to the advance direction, right?

Uh, my brain is too slow today to parse that sentence. AIUI, the deorbit burn would be done by the upward-pointing Dracos as the cosine losses for them are lower than the downward-pointing ones, due to the wall angle. So they'd be more efficient.

But at ~6 minutes deorbit burn you're hardly going to notice it anyway.

Offline ugordan

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1016 on: 01/17/2011 07:49 pm »
why 2 sets of shock cones per quadrant? 8 LAS motors?

Thrust level limits or redundancy considerations?

Offline Crispy

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1017 on: 01/17/2011 07:50 pm »
OK M1a - then here's another imagery question: why 2 sets of shock cones per quadrant? 8 LAS motors?

Redundancy, surely

Offline kraisee

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1018 on: 01/17/2011 07:58 pm »
I guess that if an abort were called at a high G part of the ascent, a shut down command would be sent to the main engine(s) before the LAS was triggered.

Yes, but in emergencies, there are never any guarantees that command will actually shut it down successfully.

Thus, your LAS design has to assume a failure to shut down the booster is one of the multitude of conditions it must cope with.

Abort systems are some of the hardest design challenges, because they have to start-out assuming most of the worst possible case scenario's have already occurred.

Ross.
« Last Edit: 01/17/2011 08:04 pm by kraisee »
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Offline baldusi

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Re: SpaceX: General Falcon and Dragon discussion (Thread 2)
« Reply #1019 on: 01/17/2011 08:03 pm »
Thus, your LAS design has to assume a failure to shut down the booster is one of the multitude of conditions it must cope with.
Shouldn't the worst acceleration condition be a case of engine overdrive? Is it even possible that a failure in one engine generates a significant extra thrust? Would this be worse (from an acceleration POV) than a catastrophic failure like Challenger?

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