Author Topic: Antares A-One General Discussion Thread (2)  (Read 47302 times)

Offline Jim

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Re: Antares A-One General Discussion Thread (2)
« Reply #20 on: 04/17/2013 05:20 PM »

I understand that the total energy is conserved during coasting, but does the long coast phase means there would be excess vertical velocity after S1 MECO? Then why the trajectory is not lowered during the first stage flight?

Can someone explain why coasting for so long?

To get the vehicle at the proper orbital parameters (altitude and perigee) at burn out. 

Offline Space Pete

Re: Antares A-One General Discussion Thread (2)
« Reply #21 on: 04/17/2013 05:21 PM »
Just want to say that I am absolutely loving Orbital's PR today - both from the internal people who are graciously taking the time to post on this forum, and from Orbital's Twitter account, which is posting minute-by-minute technical updates, and is replying to people who Tweet them to wish them luck (including me)! :)

It's more like what I remember of Shuttle launches, where there was never a quiet minute once we got past L-5h or so. I wish SpaceX could be more like this - Orbital seem to be able to do it without revealing ITAR/proprietary information.

Well done to Orbital PR!
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Offline Prober

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Re: Antares A-One General Discussion Thread (2)
« Reply #22 on: 04/17/2013 05:23 PM »

I understand that the total energy is conserved during coasting, but does the long coast phase means there would be excess vertical velocity after S1 MECO? Then why the trajectory is not lowered during the first stage flight?

Can someone explain why coasting for so long?

To get the vehicle at the proper orbital parameters (altitude and perigee) at burn out. 

Would the 1st stage be recoverable if they used chutes?
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Re: Antares A-One General Discussion Thread (2)
« Reply #23 on: 04/17/2013 05:49 PM »

Glad to see the team moving forward with prop loading ops despite the weather.  As we've seen many times, better to be ready in case the weather is acceptable.  Bonus is they get more experience and more info each time they do these functions.

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Re: Antares A-One General Discussion Thread (2)
« Reply #24 on: 04/17/2013 06:02 PM »

Cross-posting from party thread:

Will this mark the first orbital flight for the NK-33?  Yes, I know they're AJ-26, but from a heritage standpoint, will this be the first time this engine boosts an orbital payload?
Thanks!

Offline Galactic Penguin SST

Re: Antares A-One General Discussion Thread (2)
« Reply #25 on: 04/17/2013 06:11 PM »

Cross-posting from party thread:

Will this mark the first orbital flight for the NK-33?  Yes, I know they're AJ-26, but from a heritage standpoint, will this be the first time this engine boosts an orbital payload?
Thanks!

Since the NK-33 was not used on the N-1 launches (they used the less powerful NK-15), the answer is yes.
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Offline Kaputnik

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Re: Antares A-One General Discussion Thread (2)
« Reply #26 on: 04/17/2013 08:31 PM »
Apologies if this was asked already, but are there any holds in this countdown?
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Online Lar

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Re: Antares A-One General Discussion Thread (2)
« Reply #27 on: 04/17/2013 09:05 PM »
Apologies if this was asked already, but are there any holds in this countdown?

The pdf of the visitor presentation deck shows several[1].. see slide 20 for a timeline... reproduced here

L-08H 00M: Call to stations
L-07H 30M: Voice checks
L-07H 00M: Range and facility set up
L-06H 30M: Pad clear
L-06H 00M: OCCS sequencer initiation/warm helium charging
L-05H 50M: Vehicle power up and systems checks
L-03H 40M: 15 minute hold
L-03H 00M: Start of LOLS chilldown
L-01H 45M: 15 minute hold
T-01H 30M: Start of propellant loading
T-00H 25M: Start of engine low flow chilldown
T-00H 10M: Start of engine medium flow chilldown
T-00H 03M 30S: Initiate autosequencer transition (terminal count)
T-00H 03M 00S: Autosequencer control
T-00H 00M 00.5S: Initiation launch ordnance train
T-00H 00M 00S: Launch (1700 EDT)
T+1.5 seconds: Engine health checks complete
T+2 seconds: Liftoff
L+6 seconds: TEL clear

1 - well... two anyway. Which is "several" for sufficiently large values of 2 or small values of "several" :)
« Last Edit: 04/17/2013 09:06 PM by Lar »
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Offline zt

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Re: Antares A-One General Discussion Thread (2)
« Reply #28 on: 04/17/2013 09:27 PM »


U+F098 is a private use unicode character, not universally defined to mean anything. You shouldn't use it on the open web.

Online meekGee

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Re: Antares A-One General Discussion Thread (2)
« Reply #29 on: 04/17/2013 09:36 PM »
It's obviously a very different machine from the ULA launchers or Falcon-9.  Would I be right in saying that the core will get almost all the way to orbit and the U/S is little more than a kick stage to get the perigee up?

You know, I don't understand the choice of a solid U/S.  It seems to have all the wrong attributes for an U/S.

Solids, IIUC, have a high "dry" weight, since the entire "tank" is thick walled.  And in an U/S, every pound wasted is 100% at the expense of payload.

Also, it burns to depletion, so you can't control end-of-burn, so I'd think that precision insertion is problematic.

Lastly, it is not a high ISP solution.

I always thought that solids are good as either high-thrust boosters, or BEO kick stages since they are simple and can last a long time in orbit.

Anyone familiar with why they went with a solid U/S?
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Offline rayleighscatter

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Re: Antares A-One General Discussion Thread (2)
« Reply #30 on: 04/17/2013 09:37 PM »
the frontpage update here says Friday is the last shot for the month. I thought the launch window ran through Sunday?

Offline Jim

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Re: Antares A-One General Discussion Thread (2)
« Reply #31 on: 04/17/2013 09:45 PM »


You know, I don't understand the choice of a solid U/S.  It seems to have all the wrong attributes for an U/S.

Solids, IIUC, have a high "dry" weight, since the entire "tank" is thick walled.  And in an U/S, every pound wasted is 100% at the expense of payload.

Also, it burns to depletion, so you can't control end-of-burn, so I'd think that precision insertion is problematic.

Lastly, it is not a high ISP solution.

I always thought that solids are good as either high-thrust boosters, or BEO kick stages since they are simple and can last a long time in orbit.

Anyone familiar with why they went with a solid U/S?

Cost and it is in the Antares threads that you should spend more time on.

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Re: Antares A-One General Discussion Thread (2)
« Reply #32 on: 04/17/2013 09:48 PM »


U+F098 is a private use unicode character, not universally defined to mean anything. You shouldn't use it on the open web.

It's what I got when I cut'n'paste from Orbital's PDF,,, not something I made up myself. No idea why they were using it (or the software chain translated to that character on the way from the PDF source through a linux box Acrobat Reader, to my cut/paste buffer to FireFox and to your terminal)

If it's really bothering you I'll edit it out of my post :)
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Offline Kabloona

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Re: Antares A-One General Discussion Thread (2)
« Reply #33 on: 04/17/2013 09:51 PM »


Anyone familiar with why they went with a solid U/S?

IIRC, Antonio said they decided that doing a liquid first stage for the first time (for Orbital) was enough of a challenge, and that trying to simultaneously develop a liquid upper stage would have been biting off more than they could chew. An off-the-shelf solid was a lower technical and schedule risk proposition.
« Last Edit: 04/17/2013 10:01 PM by Kabloona »

Offline Kaputnik

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Re: Antares A-One General Discussion Thread (2)
« Reply #34 on: 04/17/2013 10:07 PM »


Anyone familiar with why they went with a solid U/S?

IIRC, Antonio said they decided that doing a liquid first stage for the first time (for Orbital) was enough of a challenge, and that trying to simultaneously develop a liquid upper stage would have been biting off more than they could chew. An off-the-shelf solid was a lower technical and schedule risk proposition.

And also it was at one point planned to upgrade to a liquid U/S using, IIRC, a Soyuz engine. I believe that plan is shelved at present though (shame!)
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Offline happyflower

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Re: Antares A-One General Discussion Thread (2)
« Reply #35 on: 04/17/2013 10:16 PM »
Why is it that Russians launch rockets in the middle of a snow storm / blizzard but in the US we have to worry about low cloud cover?

Offline deltaV

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Re: Antares A-One General Discussion Thread (2)
« Reply #36 on: 04/17/2013 10:22 PM »
1. Would weather have aborted the launch if the umbilical hadn't?

2. What are weather violation probabilities for the next few days?

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Re: Antares A-One General Discussion Thread (2)
« Reply #37 on: 04/17/2013 10:25 PM »


Anyone familiar with why they went with a solid U/S?

IIRC, Antonio said they decided that doing a liquid first stage for the first time (for Orbital) was enough of a challenge, and that trying to simultaneously develop a liquid upper stage would have been biting off more than they could chew. An off-the-shelf solid was a lower technical and schedule risk proposition.

ok, thanks - that makes more sense.
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Offline PreferToLurk

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Re: Antares A-One General Discussion Thread (2)
« Reply #38 on: 04/17/2013 10:26 PM »
Are we looking at a wind limitation pending a strengthening or redesign?

http://forum.nasaspaceflight.com/index.php?topic=31663.msg1039886#msg1039886

Above post indicates that the wind limit was raised prior to the scrub.

IMHO, the short term fix is to review the testing data for the strongback to ensure that nothing was missed, and then don't issue the waiver next time.

Long term redesigns (if necessary) would wait for a future launch.

Any reason to believe otherwise?

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Re: Antares A-One General Discussion Thread (2)
« Reply #39 on: 04/17/2013 10:27 PM »


You know, I don't understand the choice of a solid U/S.  It seems to have all the wrong attributes for an U/S.

Solids, IIUC, have a high "dry" weight, since the entire "tank" is thick walled.  And in an U/S, every pound wasted is 100% at the expense of payload.

Also, it burns to depletion, so you can't control end-of-burn, so I'd think that precision insertion is problematic.

Lastly, it is not a high ISP solution.

I always thought that solids are good as either high-thrust boosters, or BEO kick stages since they are simple and can last a long time in orbit.

Anyone familiar with why they went with a solid U/S?

Cost and it is in the Antares threads that you should spend more time on.

Why?  (I did read some of them.)
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