Author Topic: Antares General Discussion Thread  (Read 205321 times)

Offline dcporter

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Antares General Discussion Thread
« on: 09/21/2013 01:07 PM »
Looked down the first couple of pages and didn't find a discussion thread for the rocket that wasn't time-limited, which is weird, so if I got it wrong mods please feel free to move.

Quote from the ORB-D update thread:

A little bit off thread, but here it comes:

Taurus, Minotaur and Antares all use a Hardware AND SOFTWARE architecture Orbital calls MACH (Modular Avionics something or other, pardon me, I have little patience for that stuff...) made up of about a dozen types of "slices" (computer, I/O, power supply, ordnance drives, etc. etc.) that can be stacked up in an enclosureless-type way (i.e. each slice has its own peripheral enclosure and the ends are closed up by plates) I've seen MACH stacks as small as 5 slices and as large as 11, IIRC.  Intra-slice connections are built into the "sides" of each slice, and external connectors are on one of the sides of each slice.  The result looks a lot like a loaf of sliced brad.

Each of the above-mentioned launch vehicles has a number of differently-configured MACH "stacks" acting as the central avionics, stage remote I/O, engine controller, etc.  Slices (and stacks) communicate via Ethernet.  Indeed, a MACH stack is used in the Antares launch pad both to communicate with the rocket AND control the pad (e.g. TEL retraction after ignition.)

Pegasus used an older design but is slowly converting to the MACH architecture (the last two Pegasi flew a MAC stack as its flight computer - the resulting change in software made NASA pause and take a deep breath, but it was the right thing to do and it worked.)

More important, other Orbital products (e.g. targets) also use this architecture; the result is a) lots and lots of experience (dozens of MACH stacks and socres of MACH slices are flown every year) and b) non-trivial cost reductions.  Similar benefit with software: the amount of NEW software needed for Antares was focused on the liquid propellant elements while, for instance, the basic GN&C has long heritage (yes, even the variable-azimuth feature!...)

The MACH architecture is uniquely designed for Launch Vehicles and is not intended to be used on spacecraft, BTW.

Can anyone in the industry discuss the benefits of doing MACH as (apparently) a literal stack of hardware components rather than a modular software stack loaded into a single machine? Are the data ports required for each rocket different enough that the modular design is actually more about them than the software?

Offline kevin-rf

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Re: Antares General Discussion Thread
« Reply #1 on: 09/21/2013 01:18 PM »
Most likely it has to do with different I/O and Sensor components. Each rocket most likely has different requirements  and interface to different components and sensors (Accelerometers, Laser Ring Gyro's, GPS, ect...). I would be willing to bet that there is a CPU module and a standard bus and each additional board plugs into that bus. Each board is responsible for different parts of the I/O.

I would be curious if some of those boards contained gyro's and accellerometers or if they just interfaced to ones placed elsewhere in the rocket.

Like i said in the other thread, seems to be very PC-104 like...
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Offline Jim

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Re: Antares General Discussion Thread
« Reply #2 on: 09/21/2013 01:58 PM »

Can anyone in the industry discuss the benefits of doing MACH as (apparently) a literal stack of hardware components rather than a modular software stack loaded into a single machine? Are the data ports required for each rocket different enough that the modular design is actually more about them than the software?

It is the interface with the different stages and different types of stages.

The functional modules from which the MACH stacks are created include power transfer, ordnance initiation, booster interface,communication, and telemetry processing.
« Last Edit: 09/21/2013 02:19 PM by Jim »

Offline Antares

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Re: Antares General Discussion Thread
« Reply #3 on: 09/21/2013 08:45 PM »
I would be curious if some of those boards contained gyro's and accellerometers or if they just interfaced to ones placed elsewhere in the rocket.

IIRC, Orbital tweets from the first launch mentioned SIGI alignment steps, so it sounds like there's a separate sensor unit.
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Offline baldusi

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Re: Antares General Discussion Thread
« Reply #4 on: 09/21/2013 11:25 PM »
What's the general need of the NK-33 of extra chill down on the TP? I heard that it needed subcooled LOX or that it needs sub LOX temperature conditioning before starting. Can anybody elaborate a bit on this?

Offline antonioe

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Re: Antares General Discussion Thread
« Reply #5 on: 09/21/2013 11:32 PM »
Originally (N-1 days) to increase the volumetric efficiency of the Oxydizer system (LOX itself and tanks). However, the NK33 LOX pump bearings take advantage of the properties of the apparently superior lubricating properties of sub cooled LOX so we're stuck.

Pre-chill is a common requirement for any cryo system, sub-cooled or boiling-point.
« Last Edit: 09/21/2013 11:34 PM by antonioe »
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Offline baldusi

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Re: Antares General Discussion Thread
« Reply #6 on: 09/24/2013 06:33 PM »
Originally (N-1 days) to increase the volumetric efficiency of the Oxydizer system (LOX itself and tanks). However, the NK33 LOX pump bearings take advantage of the properties of the apparently superior lubricating properties of sub cooled LOX so we're stuck.

Pre-chill is a common requirement for any cryo system, sub-cooled or boiling-point.
So, Antares uses sub-cooler LOX, right?
During flight, doesn't the LOX heats up to boiling point? Or do you lower the boiling point by lowering the pressure? Am I asking too much?

Offline kevin-rf

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Re: Antares General Discussion Thread
« Reply #7 on: 09/24/2013 11:38 PM »
Can you heat that thermal mass of LOX quickly enough to reach the boiling point before MECO?
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Offline Prober

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Re: Antares General Discussion Thread
« Reply #8 on: 12/24/2013 11:45 PM »
This Russian video I think fits here: НК-33 - ЗАПУСК "АНТАРЕСА"
NC-33 - Launch of "Antares"   


 [youtube]Il8_OsDrHxE[/youtube]
« Last Edit: 01/16/2014 02:25 PM by Prober »
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Offline StephenB

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Re: Antares General Discussion Thread
« Reply #9 on: 01/09/2014 04:03 PM »
Can someone please post a link to the Antares launch stream? Thanks.

Offline Prober

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Offline edkyle99

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Re: Antares General Discussion Thread
« Reply #11 on: 01/16/2014 12:32 AM »
Nice review of soon to appear planned upgrades to Antares and Cygnus today over at that other site.
http://www.spaceflightnow.com/news/n1401/14orbital/#.Utc2Gvt0lpE

Cygnus, already carrying more up cargo than Dragon, will soon carry substantially more - and Orbital wants to start planning for post-2016 ISS missions soon.  Also some hints about an increasingly dim future for NK-33/AJ-26.

 - Ed Kyle
« Last Edit: 01/16/2014 01:28 AM by edkyle99 »

Offline TrevorMonty

Re: Antares General Discussion Thread
« Reply #12 on: 01/16/2014 01:17 AM »
I wonder if the Antares could handle 6- 7 Merlins.

Offline baldusi

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Re: Antares General Discussion Thread
« Reply #13 on: 01/16/2014 01:36 AM »
I wonder if the Antares could handle 6- 7 Merlins.
The core is wider than the Falcon 9, so physically yes. But it doesn't have enough isp, the piping, control and avionics would have to be redone. So it doesn't really makes much economic sense. Dual RD-191 or even an AJ-1E6 would give a much better performance with little engineering effort.

Offline arachnitect

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Re: Antares General Discussion Thread
« Reply #14 on: 01/16/2014 02:43 AM »
I wonder if the Antares could handle 6- 7 Merlins.
The core is wider than the Falcon 9, so physically yes. But it doesn't have enough isp, the piping, control and avionics would have to be redone. So it doesn't really makes much economic sense. Dual RD-191 or even an AJ-1E6 would give a much better performance with little engineering effort.

My understanding is that O/F ratio is different, so that's another big modification to the stage. I doubt SpaceX is interested in selling engines to its natural competitor for cargo resupply anyways.

The sentence that caught my attention was Culbertson saying Orbital would stick with a liquid first stage.

Online Robotbeat

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Re: Antares General Discussion Thread
« Reply #15 on: 01/16/2014 05:37 AM »
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.
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Offline kevin-rf

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Re: Antares General Discussion Thread
« Reply #16 on: 01/16/2014 11:54 AM »
Not having a down mass capability is part of why it has the better up mass.
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Offline baldusi

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Re: Antares General Discussion Thread
« Reply #17 on: 01/16/2014 12:09 PM »
Not having a down mass capability is part of why it has the better up mass.
Yep, if they were to launch on an F9, they could increase the pressure vessel to MLPM size and carry (guess) upto 5tonnes (about the average of Shuttle's MLPM).

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Re: Antares General Discussion Thread
« Reply #18 on: 01/16/2014 02:36 PM »
Nice review of soon to appear planned upgrades to Antares and Cygnus today over at that other site.
http://www.spaceflightnow.com/news/n1401/14orbital/#.Utc2Gvt0lpE

Cygnus, already carrying more up cargo than Dragon, will soon carry substantially more - and Orbital wants to start planning for post-2016 ISS missions soon.  Also some hints about an increasingly dim future for NK-33/AJ-26.

 - Ed Kyle

thx for the link

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.
 
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Offline AnalogMan

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Re: Antares General Discussion Thread
« Reply #19 on: 01/16/2014 04:22 PM »
Nice review of soon to appear planned upgrades to Antares and Cygnus today over at that other site.
http://www.spaceflightnow.com/news/n1401/14orbital/#.Utc2Gvt0lpE

Cygnus, already carrying more up cargo than Dragon, will soon carry substantially more - and Orbital wants to start planning for post-2016 ISS missions soon.  Also some hints about an increasingly dim future for NK-33/AJ-26.

 - Ed Kyle

thx for the link

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.
 

See also this article on the Castor 30XL:
http://www.nasaspaceflight.com/2013/03/castor-30xl-prepares-static-fire-antares-boost/

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