Author Topic: Cygnus-based Node 4  (Read 15211 times)

Offline manboy

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Cygnus-based Node 4
« on: 06/08/2012 01:23 am »
This has been on my mind for the past few months, and I feel like I've taken the idea as far I can go with my knowledge so I thought I might as well post it here to see how feasible it is.

Purpose: To add a berthing port to USOS (Cygnus-node nadir) that would allow a second CRS or HTV vehicle to be unberthed while a vehicle is already berthed to Node 2 nadir. To enable two berthing ports to be used for USOS expansion (Node 2 zenith and Cygnus-node zenith). To be a cheaper alternative to the Node Structural Test Article based Node 4.

It would be launched on Antares and use a largely unmodified service module. PMA-2 would have to be temporarily relocated elsewhere. As the Cygnus Node approaches the station, Canadarm2 would grab the Cygnus Node’s service module grapple fixture and berth it to Node 2 forward. The CBM hooks on Cygnus Node forward would disengage from the service module and the Canadarm2 would now remove the service module and release it. The service module would precede to de-orbit itself. PMA-2 would be relocated to Cygnus Node forward.

Module could be manufactured by Thales Alenia so ESA may be willing to pay for part of the construction cost as part of their barter agreement, I consider this a very strong point of my proposal. A Cygnus node would probably need to structurally strengthened to handle higher loads needed for a node module. Six CMBs may be too heavy for Antares, if that’s the case then the port and starboard CBMs could be deleted from the design. Module may also need to be launched near empty. My biggest concerns with my design have to do with the CBM service module attachment mechanism and the ability to de-orbit the service module by itself.
« Last Edit: 04/25/2014 05:03 am by manboy »
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Offline SpacexULA

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Re: Cygnus-based Node 4
« Reply #1 on: 06/08/2012 01:34 am »
Cygnus from what I understand is an upgraded STAR bus attached to a pressure vessel based off the MPLMs of the Shuttle, but very different.

My question would it be possible to have a Common berthing mechanism be the attachment between the modified STAR bus and another module?

That way Cygnus (or what ever you would call a Cygnus minus the PCM) could berth a module, then deorbit itself, leaving an open berthing slot on the other side of a module.

Has then ever been talked about in the forums as a use for Cygnus?
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Offline Jim

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Re: Cygnus-based Node 4
« Reply #2 on: 06/08/2012 02:31 am »
To be a cheaper alternative to the Node Structural Test Article based Node 4.


Why would it be cheaper?  the STA structure is free.

Offline Jim

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Re: Cygnus-based Node 4
« Reply #3 on: 06/08/2012 02:33 am »
CBM service module attachment mechanism

It would be a truss that interfaces with the node perimeter.  All this has been looked at for the STA Node 4. 

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« Last Edit: 06/08/2012 02:35 am by Jim »

Offline manboy

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Re: Cygnus-based Node 4
« Reply #4 on: 06/08/2012 02:50 am »
To be a cheaper alternative to the Node Structural Test Article based Node 4.


Why would it be cheaper?  the STA structure is free.
The structure would be free but its still needs to be outfitted before it can be used. For the STA a tug would need to be developed and would probably have to launch on the more expensive Atlas V.
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Offline Jim

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Re: Cygnus-based Node 4
« Reply #5 on: 06/08/2012 03:18 am »
The structure would be free but its still needs to be outfitted before it can be used. For the STA a tug would need to be developed and would probably have to launch on the more expensive Atlas V.

why couldn't it use the same tug as Cygnus?

Offline Jim

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Re: Cygnus-based Node 4
« Reply #6 on: 06/08/2012 03:22 am »
Cygnus Node


Too small of diameter for racks to hold subsystems and to be able to change out with other racks in the station.  May also be too small of diameter to support 4 radial CBM's and maybe no radial CBM's at all.

Offline Jim

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Re: Cygnus-based Node 4
« Reply #7 on: 06/08/2012 03:24 am »
Module may also need to be launched near empty.

Needs to be launched with basic systems to make it habitable and to operate CBM's and NDS

Online Orbiter

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Re: Cygnus-based Node 4
« Reply #8 on: 06/08/2012 03:28 am »
What's the point of going out of the way to purchase and modify a Cygnus with additional CBM's when you have a perfectly good (and larger, mind you) STA laying around that is virtually free of purchase and easier to modify? Though, I could possibly see the Cygnus tug being used to loft a hypothetical Node 4 to the ISS.

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Offline FinalFrontier

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Re: Cygnus-based Node 4
« Reply #9 on: 06/08/2012 03:33 am »
STA works why build something new???
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Offline Danderman

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Re: Cygnus-based Node 4
« Reply #10 on: 06/08/2012 03:39 am »
What's the point of going out of the way to purchase and modify a Cygnus with additional CBM's when you have a perfectly good (and larger, mind you) STA laying around that is virtually free of purchase and easier to modify? Though, I could possibly see the Cygnus tug being used to loft a hypothetical Node 4 to the ISS.

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If you look at lifetime costs, a Cygnus Node 4 is cheaper than a "free" STA Node 4, due to the requirement for STA to fly on EELV.

Offline Jim

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Re: Cygnus-based Node 4
« Reply #11 on: 06/08/2012 03:48 am »

If you look at lifetime costs, a Cygnus Node 4 is cheaper than a "free" STA Node 4, due to the requirement for STA to fly on EELV.


Cant say that

What says the Cygnus Node 4 can fly on Antares?
You don't know that the cost delta between Cygnus Node and STA node is less than Antares vs EELV.
« Last Edit: 06/08/2012 03:49 am by Jim »

Offline manboy

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Re: Cygnus-based Node 4
« Reply #12 on: 06/08/2012 03:51 am »
The structure would be free but its still needs to be outfitted before it can be used. For the STA a tug would need to be developed and would probably have to launch on the more expensive Atlas V.

why couldn't it use the same tug as Cygnus?

I thought the STA was confirmed to be too heavy.


If you look at lifetime costs, a Cygnus Node 4 is cheaper than a "free" STA Node 4, due to the requirement for STA to fly on EELV.


Cant say that

What says the Cygnus Node 4 can fly on Antares?
What says it can't?
« Last Edit: 06/08/2012 03:55 am by manboy »
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Offline Jim

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Re: Cygnus-based Node 4
« Reply #13 on: 06/08/2012 03:56 am »

I thought the STA was confirmed to be too heavy.


Too heavy for what?

Offline manboy

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Re: Cygnus-based Node 4
« Reply #14 on: 06/08/2012 03:57 am »

I thought the STA was confirmed to be too heavy.


Too heavy for what?
For Cygnus' service module.
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Offline FinalFrontier

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Re: Cygnus-based Node 4
« Reply #15 on: 06/08/2012 03:58 am »

I thought the STA was confirmed to be too heavy.


Too heavy for what?
For Cygnus' service module.

  ???

Okay what?
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Offline Jim

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Re: Cygnus-based Node 4
« Reply #16 on: 06/08/2012 03:59 am »

What says it can't?

You can't say either way.  But it isn't the current Cygnus.  The existing pressure shell is not useable.  It not designed for radial holes nor being hit on the end by a docking spacecraft.  It is going to take more metal in the hull to accept loads from these.

Offline Jim

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Re: Cygnus-based Node 4
« Reply #17 on: 06/08/2012 04:00 am »

I thought the STA was confirmed to be too heavy.


Too heavy for what?
For Cygnus' service module.

where is that documented?

Offline manboy

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Re: Cygnus-based Node 4
« Reply #18 on: 06/08/2012 04:00 am »

I thought the STA was confirmed to be too heavy.


Too heavy for what?
For Cygnus' service module.

  ???

Okay what?
Jim asked why the STA couldn't use Cygnus' service module.


What says it can't?

You can't say either way.  But it isn't the current Cygnus.  The existing pressure shell is not useable.  It not designed for radial holes nor being hit on the end by a docking spacecraft.  It is going to take more metal in the hull to accept loads from these.
And I mentioned that in the original post.


I thought the STA was confirmed to be too heavy.


Too heavy for what?
For Cygnus' service module.

where is that documented?
I was going off of Pete's old article where it mentions it would be transported on the Advanced Rendezvous & Docking Vehicle.
« Last Edit: 06/08/2012 04:09 am by manboy »
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Offline pathfinder_01

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Re: Cygnus-based Node 4
« Reply #19 on: 06/08/2012 04:59 am »
I know that with the pervious unpressurized version of Cgynus, it would have handled a module roughly the same size and mass as the pressurized module. From what I can tell STA masses about 11MT or so and is larger than the pressurized section of Cygnus. I don't think Cygnus can do so without some modification.

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