Author Topic: Antares General Discussion Thread  (Read 205320 times)

Offline baldusi

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Re: Antares General Discussion Thread
« Reply #20 on: 01/16/2014 04:46 PM »
Found this interesting: " Antares rocket's more powerful Castor 30XL upper stage motor provided by ATK. The Castor 30XL is a lengthened version of the Antares rocket's flight-proven Castor 30 motor, boosting the launcher's maximum load to the space station by more than 1,000 pounds."

Something to be said for the simple design.
Castor 30XL is sort of the performance limit of the solid US. If you look at high energy performance, they use the 121/2, because the Antares first stage has little T/W, and thus the gravity losses of carring the XL are greater than the extra impulse. So, for LEO the XL wins but for escape, the smaller B is a better choice.
Remember that the Antares is supposed to be used for small missions. And the "heavy" to LEO was only needed for CRS.
BTW, the core has little T/W because the that way you'd need no changes for a better propulsion (like RD-180 or AJ-1E6) to get extra performance. Ditto with a liquid upper stage.

Offline edkyle99

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Re: Antares General Discussion Thread
« Reply #21 on: 01/17/2014 04:36 AM »
Castor 30XL is sort of the performance limit of the solid US. If you look at high energy performance, they use the 121/2, because the Antares first stage has little T/W, and thus the gravity losses of carring the XL are greater than the extra impulse. So, for LEO the XL wins but for escape, the smaller B is a better choice.
Remember that the Antares is supposed to be used for small missions. And the "heavy" to LEO was only needed for CRS.
BTW, the core has little T/W because the that way you'd need no changes for a better propulsion (like RD-180 or AJ-1E6) to get extra performance. Ditto with a liquid upper stage.
The Antares User's Guide seems to show that the 130 series boosts more payload to both LEO and escape than the 120 series.  The difference between the two does seem to narrow substantially for the higher energy missions.  One factor may be that both use the same Star 48BV third stage.

 - Ed Kyle
« Last Edit: 01/17/2014 04:46 AM by edkyle99 »

Offline woods170

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Re: Antares General Discussion Thread
« Reply #22 on: 01/17/2014 07:06 AM »
Not having a down mass capability is part of why it has the better up mass.
Bingo!  And people should remember there is no 'contest'  between Orbital and SpaceX with regards to upmass. Check the CRS contracts. It has been clear from the very beginning that Orbital was to deliver substantially more upmass than SpaceX. They can do so, because the shape of their pressurized compartment is optimal for upmass. But only SpaceX Dragon can provide downmass. Comparing them on upmass capabilities is apples-to-oranges.

Offline Ben the Space Brit

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Re: Antares General Discussion Thread
« Reply #23 on: 01/17/2014 09:35 AM »
FWIW, I'd still love to see an ORB/SpaceX demonstrator mission with a ECLSS-equipped Cygnus as a long-duration hab module for low-frills commercial passenger flights.

It could neatly pre-empt Bigelow and I bet Space Adventures have enough clients lined up that they'd enjoy having an alternate provider/destination than Soyuz and the ISS. So long as it has a couple of large view-ports and multi-role power/cooling ports for passenger equipment and personal experiments, it should be fine!
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Offline Lurker Steve

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Re: Antares General Discussion Thread
« Reply #24 on: 01/17/2014 02:13 PM »
FWIW, I'd still love to see an ORB/SpaceX demonstrator mission with a ECLSS-equipped Cygnus as a long-duration hab module for low-frills commercial passenger flights.

It could neatly pre-empt Bigelow and I bet Space Adventures have enough clients lined up that they'd enjoy having an alternate provider/destination than Soyuz and the ISS. So long as it has a couple of large view-ports and multi-role power/cooling ports for passenger equipment and personal experiments, it should be fine!

What you will see first is Cygnus flying as a standalone craft, flying experiments in LEO after it's ISS supply mission has completed. There is no rush to perform the destructive re-entry, and there is power and communication to operate as a free-flier for quite a long while. No ECLSS required since no humans are on board.

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Re: Antares General Discussion Thread
« Reply #25 on: 01/17/2014 03:03 PM »
FWIW, I'd still love to see an ORB/SpaceX demonstrator mission with a ECLSS-equipped Cygnus as a long-duration hab module for low-frills commercial passenger flights.

It could neatly pre-empt Bigelow and I bet Space Adventures have enough clients lined up that they'd enjoy having an alternate provider/destination than Soyuz and the ISS. So long as it has a couple of large view-ports and multi-role power/cooling ports for passenger equipment and personal experiments, it should be fine!

What you will see first is Cygnus flying as a standalone craft, flying experiments in LEO after it's ISS supply mission has completed. There is no rush to perform the destructive re-entry, and there is power and communication to operate as a free-flier for quite a long while. No ECLSS required since no humans are on board.
That sounds awesome, do you have any links with more info for those interested?
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Offline baldusi

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Re: Antares General Discussion Thread
« Reply #26 on: 01/17/2014 03:19 PM »
FWIW, I'd still love to see an ORB/SpaceX demonstrator mission with a ECLSS-equipped Cygnus as a long-duration hab module for low-frills commercial passenger flights.

It could neatly pre-empt Bigelow and I bet Space Adventures have enough clients lined up that they'd enjoy having an alternate provider/destination than Soyuz and the ISS. So long as it has a couple of large view-ports and multi-role power/cooling ports for passenger equipment and personal experiments, it should be fine!

What you will see first is Cygnus flying as a standalone craft, flying experiments in LEO after it's ISS supply mission has completed. There is no rush to perform the destructive re-entry, and there is power and communication to operate as a free-flier for quite a long while. No ECLSS required since no humans are on board.
Actually, not for long term, that why we have the ISS. But ORB-2, I think, will have an Internal Fire experiment. They'll basically set the pressure vessel on fire and film it just before reentry. That way they'll have a much better understanding of fire propagation inside any module.
So as a platform for experiments too dangerous to do un the ISS its already being used.

Offline fatjohn1408

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Re: Antares General Discussion Thread
« Reply #27 on: 01/17/2014 04:38 PM »
Castor 30XL is sort of the performance limit of the solid US. If you look at high energy performance, they use the 121/2, because the Antares first stage has little T/W, and thus the gravity losses of carring the XL are greater than the extra impulse. So, for LEO the XL wins but for escape, the smaller B is a better choice.
Remember that the Antares is supposed to be used for small missions. And the "heavy" to LEO was only needed for CRS.
BTW, the core has little T/W because the that way you'd need no changes for a better propulsion (like RD-180 or AJ-1E6) to get extra performance. Ditto with a liquid upper stage.
The Antares User's Guide seems to show that the 130 series boosts more payload to both LEO and escape than the 120 series.  The difference between the two does seem to narrow substantially for the higher energy missions.  One factor may be that both use the same Star 48BV third stage.

 - Ed Kyle

Yes the brochure can be found here btw: http://www.orbital.com/Newsinfo/Publications/Antares_Brochure.pdf

A question what is Antares its GTO capacity? can you just assume that it can bring the same payload to GTO as it can to a -8.2 km^2/s^2 C3 orbit? Thus being around 1.5t for the 132 version?

I would expect the first and the second stage to be a bit more capable than just bringing the Star 48 (2t) and 1.5t payload into LEO, therefore the GTO insertion burn (with the star 48) must be done from an already quite elliptical LEO orbit.

Where would the burn be done? At perigee, to efficiently raise the orbit apogee or at apogee to efficiently change the inclination plane?

Offline arachnitect

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Re: Antares General Discussion Thread
« Reply #28 on: 01/17/2014 05:12 PM »
Castor 30XL is sort of the performance limit of the solid US. If you look at high energy performance, they use the 121/2, because the Antares first stage has little T/W, and thus the gravity losses of carring the XL are greater than the extra impulse. So, for LEO the XL wins but for escape, the smaller B is a better choice.
Remember that the Antares is supposed to be used for small missions. And the "heavy" to LEO was only needed for CRS.
BTW, the core has little T/W because the that way you'd need no changes for a better propulsion (like RD-180 or AJ-1E6) to get extra performance. Ditto with a liquid upper stage.
The Antares User's Guide seems to show that the 130 series boosts more payload to both LEO and escape than the 120 series.  The difference between the two does seem to narrow substantially for the higher energy missions.  One factor may be that both use the same Star 48BV third stage.

 - Ed Kyle

132 has more performance than 122 up to about 1500kg where its curve stops. My SWAG is that, with less than 1500kg, second stage acceleration gets too high: see the second image. 122 does well above 6.5g, but only during the Star48 burn.

You could add another stage (Star 27H?) if you wanted to send a cubesat to Neptune or something.

Offline edkyle99

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Re: Antares General Discussion Thread
« Reply #29 on: 01/17/2014 07:33 PM »
132 has more performance than 122 up to about 1500kg where its curve stops. My SWAG is that, with less than 1500kg, second stage acceleration gets too high: see the second image. 122 does well above 6.5g, but only during the Star48 burn.
I wondered about that.  The 2012 version of the brochure showed the curve continuing past 1,500 kg.

 - Ed Kyle
« Last Edit: 01/17/2014 07:33 PM by edkyle99 »

Offline edkyle99

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Re: Antares General Discussion Thread
« Reply #30 on: 01/17/2014 08:06 PM »
A question what is Antares its GTO capacity? can you just assume that it can bring the same payload to GTO as it can to a -8.2 km^2/s^2 C3 orbit? Thus being around 1.5t for the 132 version?
Something along those lines, but I'm not certain of the precise delta-v difference.  One reference gives 700 m/s delta-v between C3=0 and GTO.  Based on that, my guesstimate is better than 1.4 tonnes to GTO for 122 and more than 1.7 tonnes for 132, but as you mentioned energy management for these all-solid upper stage setups would be an issue.  The post-Castor 30(XL) parking orbit would have to be elliptical. 

 - Ed Kyle
« Last Edit: 01/17/2014 08:35 PM by edkyle99 »

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Re: Antares General Discussion Thread
« Reply #31 on: 01/18/2014 10:42 PM »
I wonder if the Antares could handle 6- 7 Merlins.
Just launch Cygnus on Falcon 9 if you're going that route. If you're talking just bulky cargo upmass, Cygnus is simply better than Dragon for the same mass.

Exactly. Cygnus and Dragon both fill important niches and have different and complementary capabilities. Dragon could theoretically launch up to 6000kg of cargo, but with how small its pressurized volume is, it would need cargo with an effective density of over 500kg/m^3 to max out its mass capacity. Admittedly, Dragon on a F9 with reusable first stage would likely be a lot better matched between available volume and net cargo mass capacity.

But yeah, I'm glad we've got both vehicles flying.

~Jon

Offline fatjohn1408

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Re: Antares General Discussion Thread
« Reply #32 on: 01/20/2014 07:39 AM »
Castor 30XL is sort of the performance limit of the solid US. If you look at high energy performance, they use the 121/2, because the Antares first stage has little T/W, and thus the gravity losses of carring the XL are greater than the extra impulse. So, for LEO the XL wins but for escape, the smaller B is a better choice.
Remember that the Antares is supposed to be used for small missions. And the "heavy" to LEO was only needed for CRS.
BTW, the core has little T/W because the that way you'd need no changes for a better propulsion (like RD-180 or AJ-1E6) to get extra performance. Ditto with a liquid upper stage.
The Antares User's Guide seems to show that the 130 series boosts more payload to both LEO and escape than the 120 series.  The difference between the two does seem to narrow substantially for the higher energy missions.  One factor may be that both use the same Star 48BV third stage.

 - Ed Kyle

132 has more performance than 122 up to about 1500kg where its curve stops. My SWAG is that, with less than 1500kg, second stage acceleration gets too high: see the second image. 122 does well above 6.5g, but only during the Star48 burn.

You could add another stage (Star 27H?) if you wanted to send a cubesat to Neptune or something.

Huh? You posted the 132 and there the 3rd stage (Star 48) did not even get to 4g. the 2nd stage got high g's

Offline arachnitect

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Re: Antares General Discussion Thread
« Reply #33 on: 01/20/2014 07:08 PM »
Castor 30XL is sort of the performance limit of the solid US. If you look at high energy performance, they use the 121/2, because the Antares first stage has little T/W, and thus the gravity losses of carring the XL are greater than the extra impulse. So, for LEO the XL wins but for escape, the smaller B is a better choice.
Remember that the Antares is supposed to be used for small missions. And the "heavy" to LEO was only needed for CRS.
BTW, the core has little T/W because the that way you'd need no changes for a better propulsion (like RD-180 or AJ-1E6) to get extra performance. Ditto with a liquid upper stage.
The Antares User's Guide seems to show that the 130 series boosts more payload to both LEO and escape than the 120 series.  The difference between the two does seem to narrow substantially for the higher energy missions.  One factor may be that both use the same Star 48BV third stage.

 - Ed Kyle

132 has more performance than 122 up to about 1500kg where its curve stops. My SWAG is that, with less than 1500kg, second stage acceleration gets too high: see the second image. 122 does well above 6.5g, but only during the Star48 burn.

You could add another stage (Star 27H?) if you wanted to send a cubesat to Neptune or something.

Huh? You posted the 132 and there the 3rd stage (Star 48) did not even get to 4g. the 2nd stage got high g's

Here, I fix:

Quote
132 has more performance than 122 up to about 1500kg where its curve stops. My SWAG is that, with less than 1500kg, second stage acceleration gets too high: see the 132 graph attached to my previous post, where second stage acceleration can be as high as 6.5g. If you look at the corresponding graph for the 122 (attached), you can see that it has higher acceleration -but only during the Star48 burn.

The question is "why can't the 132 turn it's payload advantage into higher C3?" and I think the answer is that the second stage burn acceleration is too high with smaller payloads.

Offline Chris Bergin

Re: Antares General Discussion Thread
« Reply #34 on: 02/13/2014 02:58 PM »
Not sure which thread to ask this in, but this seems close.

Orbital have announced their 2013 financial figures and outlook. Interesting enough for an article, but how do I search their past 12 months on their stock price? I want to see if there's been a rise in the price reflecting their successes.

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Offline Lurker Steve

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Re: Antares General Discussion Thread
« Reply #36 on: 02/13/2014 03:18 PM »
Not sure which thread to ask this in, but this seems close.

Orbital have announced their 2013 financial figures and outlook. Interesting enough for an article, but how do I search their past 12 months on their stock price? I want to see if there's been a rise in the price reflecting their successes.

Pretty much all of the major portals (yahoo, google, etc)  have some sort of stock quote service available, and they all come with charts. I'm sure you could even access quotes via eTrade without logging into with an account.

If you are going to watch the stock price, you should check the rate of increase pre-Antares and post-Antares, if you are writing an Antares / Cyngus related article. I assume the rest of their business lines are doing fairly well.

Offline Chris Bergin

Re: Antares General Discussion Thread
« Reply #37 on: 02/13/2014 03:30 PM »
Thanks guys, that's perfect!

Offline Avron

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Re: Antares General Discussion Thread
« Reply #38 on: 03/02/2014 11:33 PM »
I wonder how come there is no activity here.. with engine needs and what the supply line looks like going forward

Offline arachnitect

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Re: Antares General Discussion Thread
« Reply #39 on: 03/02/2014 11:50 PM »
I wonder how come there is no activity here.. with engine needs and what the supply line looks like going forward

What's there to say? No news from an engineering perspective. The politics needs to stay in the politics section.

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