Author Topic: Orbital ATK highlights advancements to Cygnus for CRS-2 contract flights  (Read 3759 times)


Offline BrightLight

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Another outstanding article, I didn't know that Cygnus has a unpressurized version, very informative.

Offline Skyrocket

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Another outstanding article, I didn't know that Cygnus has a unpressurized version, very informative.

An unpressurized version was already offered for CRS-1, but was not ordered.

http://space.skyrocket.de/doc_sdat/cygnus-ucm.htm

Offline okan170

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Another outstanding article, I didn't know that Cygnus has a unpressurized version, very informative.

An unpressurized version was already offered for CRS-1, but was not ordered.

http://space.skyrocket.de/doc_sdat/cygnus-ucm.htm

Heres an older animation of it, from the days when Antares was "Taurus II".  (skip to 1:45)


An interesting thing from the article is the bit about late-loading cargo within a day of launch.  Would you need to use the crew access arm to do this for Atlas V?  ULA did mention making changes to the white room to support additional customers, is it possible to use it to access a cargo vehicle on the pad?
« Last Edit: 04/26/2017 07:40 PM by okan170 »

Offline Coastal Ron

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Great article.

I'm a great believer in commodity transportation, and I believe that one of the methods of lowering the cost to access space is to standardize on cargo containers.  This has worked very well for terrestrial transportation, where the same container can be transported by truck, rail, sea, and even air.

My concern with the different varieties of Cygnus Pressurized Cargo Modules (PCM) is that "too many versions" starts becoming "too customized", and it removes the cost benefit of commodity transportation.  Is two pressurized versions "too many"?  Maybe.

However if the larger sized PCM was to become a new standard size itself that can be adopted by others, then that would be different.  Just as Intermodal containers can have different standard lengths.

Just a thought...
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline IanThePineapple

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I wonder if the larger Cygnus will add another "section" onto the pressurized module, like what they did from the standard to enhanced Cygnus
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Offline brickmack

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I wonder if the larger Cygnus will add another "section" onto the pressurized module, like what they did from the standard to enhanced Cygnus

Most likely. This fits very well with the images they've shown of a 4 segment Cygnus derived habitat module, its probably meant to be a common design. Not much sense moving to a larger diameter since that would be so much more expensive (another set of tooling, with far lower demand), and they're not limited by length yet. Atlas V 401 isn't wide enough to carry an MPLM anyway (the most likely basis of a widebody Cygnus), and 501 is more expensive and has lower mass capacity

Offline Sesquipedalian

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Another outstanding article, I didn't know that Cygnus has a unpressurized version, very informative.

All companies were required to bid both pressurized and unpressurized capability for CRS-2.  But I'm disappointed that OA hasn't publicized their unpressurized version to the same extent.  In fact, aside from early videos such as the one okan170 posted, there's barely any public information on it at all.

Offline Lars-J

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Another outstanding article, I didn't know that Cygnus has a unpressurized version, very informative.

All companies were required to bid both pressurized and unpressurized capability for CRS-2.  But I'm disappointed that OA hasn't publicized their unpressurized version to the same extent.  In fact, aside from early videos such as the one okan170 posted, there's barely any public information on it at all.

They had an unpressurized Cygnus option for CRS-1 as well.  An unpressurized version was mentioned back in their COTS proposal in 2008: https://www.wired.com/2008/02/nasa-awards-170/

Quote
"According to their website, they are already at work on the new vehicle, the Taurus II, to launch pressurized and unpressurized cargo to the International Space Station."

Offline Sam Ho

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There was some discussion of the unpressurized Cygnus in the Cygnus update thread a few months back.  I would imagine part of the reason there's so little mention of it is that none have been ordered yet.

A small update on CRS2 and Cygnus, the initial CRS2 missions will be enhanced Cygnus' which berth (see slide below and the discussion of it at 5:55 of the video). It is not really surprising but NASA only ordered the pressurized cargo Cygnus (not OATK's unpressurized cargo spacecraft).

Offline GWH

A recent conversation regarding the Pergrine lander being launched with Cygnus on an Atlas 531 brought up the question of what vehicle the extended CRS2 Cygnus would fly on. Currently the extra extended 4 meter fairing is used, so will the longer modules require a 5 meter fairing for the extra length?

Offline Steven Pietrobon

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A recent conversation regarding the Pergrine lander being launched with Cygnus on an Atlas 531 brought up the question of what vehicle the extended CRS2 Cygnus would fly on. Currently the extra extended 4 meter fairing is used, so will the longer modules require a 5 meter fairing for the extra length?

The extended Cygnus has already flown on Atlas V (OA-4, OA-6 and OA-7). It used the 4 m fairing. From the rocketbuilder web site, you can have three boosters with the 4 or 5 m fairing, so presumably they are using the 5 m fairing for the extra length with the Peregrine Lunar Lander.

http://space.skyrocket.de/doc_sdat/cygnus-pcm-e.htm
« Last Edit: 08/18/2017 07:54 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline GWH

A recent conversation regarding the Pergrine lander being launched with Cygnus on an Atlas 531 brought up the question of what vehicle the extended CRS2 Cygnus would fly on. Currently the extra extended 4 meter fairing is used, so will the longer modules require a 5 meter fairing for the extra length?

The extended Cygnus has already flown on Atlas V (OA-4, OA-6 and OA-7). It used the 4 m fairing. From the rocketbuilder web site, you can have three boosters with the 4 or 5 m fairing, so presumably they are using the 5 m fairing for the extra length with the Peregrine Lunar Lander.

http://space.skyrocket.de/doc_sdat/cygnus-pcm-e.htm

By "extended" I wasn't referring to the Enhanced Cygnus already flying, but rather addressing this quote from the topic article:
Quote from: NASA Space Flight
The first version of Cygnus for the CRS-2 contract is similar to the current version of Cygnus, upgraded to carry 10 to 15% more pressurized cargo than CRS-1 Cygnus vehicles can.
But Orbital ATK didn’t stop there.  “We also offered a bigger version with an even larger PCM (Pressurized Cargo Module) that would have to use an Atlas V rocket,” stated Mr. DeMauro.

Given that the original Cygnus was a 2 segment x 5.1m long, enhanced is 3 segment x 6.3m, I would assume the larger version referenced above would be 4 segment x 7.5m long.

The total non-tapered length available within the 4-m XEPF is about 5.8m, So I am guessing a 4 segment would not fit. Without doing a CAD sketch but rather just eyeballing it the 4seg module would probably fit in the 5m short fairing.

http://www.globalsecurity.org/space/systems/images/atlas_V_payload2.jpg
« Last Edit: 08/18/2017 04:06 PM by GWH »

Offline russianhalo117

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A recent conversation regarding the Pergrine lander being launched with Cygnus on an Atlas 531 brought up the question of what vehicle the extended CRS2 Cygnus would fly on. Currently the extra extended 4 meter fairing is used, so will the longer modules require a 5 meter fairing for the extra length?

The extended Cygnus has already flown on Atlas V (OA-4, OA-6 and OA-7). It used the 4 m fairing. From the rocketbuilder web site, you can have three boosters with the 4 or 5 m fairing, so presumably they are using the 5 m fairing for the extra length with the Peregrine Lunar Lander.

http://space.skyrocket.de/doc_sdat/cygnus-pcm-e.htm

By "extended" I wasn't referring to the Enhanced Cygnus already flying, but rather addressing this quote from the topic article:
Quote from: NASA Space Flight
The first version of Cygnus for the CRS-2 contract is similar to the current version of Cygnus, upgraded to carry 10 to 15% more pressurized cargo than CRS-1 Cygnus vehicles can.
But Orbital ATK didn’t stop there.  “We also offered a bigger version with an even larger PCM (Pressurized Cargo Module) that would have to use an Atlas V rocket,” stated Mr. DeMauro.

Given that the original Cygnus was a 2 segment x 5.1m long, enhanced is 3 segment x 6.3m, I would assume the larger version referenced above would be 4 segment x 7.5m long.

The total non-tapered length available within the 4-m XEPF is about 5.8m, So I am guessing a 4 segment would not fit. Without doing a CAD sketch but rather just eyeballing it the 4seg module would probably fit in the 5m short fairing.

http://www.globalsecurity.org/space/systems/images/atlas_V_payload2.jpg

The Centaur Launch Adapter takes up more length than the standard PAF/PLA that is normally used.

Offline GWH

By "extended" I wasn't referring to the Enhanced Cygnus already flying, but rather addressing this quote from the topic article:
Quote from: NASA Space Flight
The first version of Cygnus for the CRS-2 contract is similar to the current version of Cygnus, upgraded to carry 10 to 15% more pressurized cargo than CRS-1 Cygnus vehicles can.
But Orbital ATK didn’t stop there.  “We also offered a bigger version with an even larger PCM (Pressurized Cargo Module) that would have to use an Atlas V rocket,” stated Mr. DeMauro.

Given that the original Cygnus was a 2 segment x 5.1m long, enhanced is 3 segment x 6.3m, I would assume the larger version referenced above would be 4 segment x 7.5m long.

The total non-tapered length available within the 4-m XEPF is about 5.8m, So I am guessing a 4 segment would not fit. Without doing a CAD sketch but rather just eyeballing it the 4seg module would probably fit in the 5m short fairing.

http://www.globalsecurity.org/space/systems/images/atlas_V_payload2.jpg

The Centaur Launch Adapter takes up more length than the standard PAF/PLA that is normally used.

Continuing on this thread, and trying to estimate mass an launch vehicle requirements of a 4 segment Cygnus, pulling data from OA-6:
Cygnus Standard (2 segment) dry mass: 1500 kg
Cygnus Enhanced (3 segment) dry mass: 1800 kg (300 kg more)
OA-6 Launch Mass: 7400 kg
OA-6 Cargo Mass: 3513 kg
OA-6 Remaining Mass from total: 2087 kg (assume this is propellant, and adapter?)
Sources:
https://en.wikipedia.org/wiki/Cygnus_(spacecraft)
http://www.ulalaunch.com/uploads/docs/Mission_Booklets/AV/av_oa6_mob.pdf


4 Segment:
Cargo Mass + 15% = 4040 kg
Extra segment Dry Mass + 300 kg = 2100 kg
Additional mass as per above: 2087 kg
Total estimated 4 segment mass = 8227 kg

From rocketbuilder.com the max launch mass of a Atlas V 501 short fairing to 200 km LEO is 8100 kg. Changes to fairing length have a negligible effect on payload.
To get the actual payload to the 400 km 51.6deg inclination ISS orbit I used NASA's launch vehicle performance website, which lists:
Atlas V 501 short fairing: 6700 kg
Atlas V 511 short fairing: 9245 kg
Atlas V 521 short fairing: 11460 kg
Atlas V 521 short fairing: 13345 kg
https://elvperf.ksc.nasa.gov/pages/Query.aspx


So given the information and assumptions above it would seem to me the default vehicle for these new CRS2 extra extended 4 segment Cygnus missions would probably be the Atlas 511, a never flown variant.

Offline russianhalo117

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By "extended" I wasn't referring to the Enhanced Cygnus already flying, but rather addressing this quote from the topic article:
Quote from: NASA Space Flight
The first version of Cygnus for the CRS-2 contract is similar to the current version of Cygnus, upgraded to carry 10 to 15% more pressurized cargo than CRS-1 Cygnus vehicles can.
But Orbital ATK didn’t stop there.  “We also offered a bigger version with an even larger PCM (Pressurized Cargo Module) that would have to use an Atlas V rocket,” stated Mr. DeMauro.

Given that the original Cygnus was a 2 segment x 5.1m long, enhanced is 3 segment x 6.3m, I would assume the larger version referenced above would be 4 segment x 7.5m long.

The total non-tapered length available within the 4-m XEPF is about 5.8m, So I am guessing a 4 segment would not fit. Without doing a CAD sketch but rather just eyeballing it the 4seg module would probably fit in the 5m short fairing.

http://www.globalsecurity.org/space/systems/images/atlas_V_payload2.jpg

The Centaur Launch Adapter takes up more length than the standard PAF/PLA that is normally used.

Continuing on this thread, and trying to estimate mass an launch vehicle requirements of a 4 segment Cygnus, pulling data from OA-6:
Cygnus Standard (2 segment) dry mass: 1500 kg
Cygnus Enhanced (3 segment) dry mass: 1800 kg (300 kg more)
OA-6 Launch Mass: 7400 kg
OA-6 Cargo Mass: 3513 kg
OA-6 Remaining Mass from total: 2087 kg (assume this is propellant, and adapter?)
Sources:
https://en.wikipedia.org/wiki/Cygnus_(spacecraft)
http://www.ulalaunch.com/uploads/docs/Mission_Booklets/AV/av_oa6_mob.pdf


4 Segment:
Cargo Mass + 15% = 4040 kg
Extra segment Dry Mass + 300 kg = 2100 kg
Additional mass as per above: 2087 kg
Total estimated 4 segment mass = 8227 kg

From rocketbuilder.com the max launch mass of a Atlas V 501 short fairing to 200 km LEO is 8100 kg. Changes to fairing length have a negligible effect on payload.
To get the actual payload to the 400 km 51.6deg inclination ISS orbit I used NASA's launch vehicle performance website, which lists:
Atlas V 501 short fairing: 6700 kg
Atlas V 511 short fairing: 9245 kg
Atlas V 521 short fairing: 11460 kg
Atlas V 521 short fairing: 13345 kg
https://elvperf.ksc.nasa.gov/pages/Query.aspx


So given the information and assumptions above it would seem to me the default vehicle for these new CRS2 extra extended 4 segment Cygnus missions would probably be the Atlas 511, a never flown variant.

Unless ULA rolls out the new extended composite fairing planned for the Vulcan-Centaur 400 series a bit early.
« Last Edit: 08/22/2017 11:05 PM by russianhalo117 »

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