What's the pressurized volume of a CST-100?
[Boeing VP and program manager John] Mulholland said, measured in mass, the Boeing design for the cargo module was 96-percent complete at the time of the review, while its design for the crew module was 85-percent complete, two metrics that underscored the maturity of the design.
I like Ferguson, and I think he shoots straight. You think Musk and Sirangelo haven't been feeding us carefully qualified half truths? It frustrates me that people can just slag the guy and nobody cares.
ISTM the problem with CST-100 for COTS-2 is a small hatch and lack of an unpressurized cargo bay like Dragon's trunk. Adding the latter would have to be a service module extension, and that would cover the circular solar panel at its bottom. It would also add even more mass, perhaps requiring at least one more $RB.Seems by using an expensive, disposable service module instead of integrating it like DV2 & DC they've painted themselves into a corner.My $0.02
Quote from: baldusi on 08/22/2014 01:30 amWhat's the pressurized volume of a CST-100?http://forum.nasaspaceflight.com/index.php?topic=22125.msg740682#msg740682People are estimating 16-20m3 (I bet usable volume is maybe half that? I'm too tired to fire up CAD right now).I've seen "more than 1100kg" and "up to 1300kg" for cargo capacity.
Quote from: Rifleman on 08/21/2014 10:45 pmQuote from: docmordrid on 08/21/2014 09:57 pmISTM the problem with CST-100 for COTS-2 is a small hatch and lack of an unpressurized cargo bay like Dragon's trunk. Adding the latter would have to be a service module extension, and that would cover the circular solar panel at its bottom. It would also add even more mass, perhaps requiring at least one more $RB.Seems by using an expensive, disposable service module instead of integrating it like DV2 & DC they've painted themselves into a corner.My $0.02I think a CST-100 derived freighter would compete much better against Orbital than it would SpaceX. Cygnus already has a smaller hatch diameter and no unpressurized cargo capacity, and as of COTS-1, is significantly more expensive than Dragon. I'd think it's the other way around. Cygnus covers the bulky cargo and trash disposal. You are correct about the unpressurized cargo of course. Cygnus could go to a full sized CBM hatch if desired, CST can't.
Quote from: docmordrid on 08/21/2014 09:57 pmISTM the problem with CST-100 for COTS-2 is a small hatch and lack of an unpressurized cargo bay like Dragon's trunk. Adding the latter would have to be a service module extension, and that would cover the circular solar panel at its bottom. It would also add even more mass, perhaps requiring at least one more $RB.Seems by using an expensive, disposable service module instead of integrating it like DV2 & DC they've painted themselves into a corner.My $0.02I think a CST-100 derived freighter would compete much better against Orbital than it would SpaceX. Cygnus already has a smaller hatch diameter and no unpressurized cargo capacity, and as of COTS-1, is significantly more expensive than Dragon.
I have to wonder what they would charge under a commercial contract for a 4.5m diameter tin can to launch on Falcon Heavy... and whether it would be substantially cheaper than the Japanese and European entrants.
Quote from: arachnitect on 08/22/2014 01:13 amQuote from: Rifleman on 08/21/2014 10:45 pmQuote from: docmordrid on 08/21/2014 09:57 pmISTM the problem with CST-100 for COTS-2 is a small hatch and lack of an unpressurized cargo bay like Dragon's trunk. Adding the latter would have to be a service module extension, and that would cover the circular solar panel at its bottom. It would also add even more mass, perhaps requiring at least one more $RB.Seems by using an expensive, disposable service module instead of integrating it like DV2 & DC they've painted themselves into a corner.My $0.02I think a CST-100 derived freighter would compete much better against Orbital than it would SpaceX. Cygnus already has a smaller hatch diameter and no unpressurized cargo capacity, and as of COTS-1, is significantly more expensive than Dragon. I'd think it's the other way around. Cygnus covers the bulky cargo and trash disposal. You are correct about the unpressurized cargo of course. Cygnus could go to a full sized CBM hatch if desired, CST can't.The proposal is out there to turn Cygnus into a (perhaps not reusable) return capsule, via a HIAD, in the HEART test. I can't find anything from the HIAD team less than a year old though, despite the fact that they should have been on the PR warpath for IRVE-4 this past spring.The Cygnus team also seems pretty damn flexible as far as the scale of their 3m diameter tin can. The 2-segment craft is being replaced by a 3-segment 'enhanced' craft as they develop Antares further, with a 4-segment craft proposed if anyone wants to fund it, and I think there were whispers of an even longer one.I have to wonder what they would charge under a commercial contract for a 4.5m diameter tin can to launch on Falcon Heavy... and whether it would be substantially cheaper than the Japanese and European entrants.
Quote from: docmordrid on 08/21/2014 09:57 pmISTM the problem with CST-100 for COTS-2 is a small hatch and lack of an unpressurized cargo bay like Dragon's trunk. Adding the latter would have to be a service module extension, and that would cover the circular solar panel at its bottom. It would also add even more mass, perhaps requiring at least one more $RB.Seems by using an expensive, disposable service module instead of integrating it like DV2 & DC they've painted themselves into a corner.My $0.02I do not get this fascination with unpressurized cargo.There is no indication that NASA needs a lot of it.The retiring ATV has no unpressurized cargo capability.Volume and re-boost are its two big features.The current ATV caries over 4 mt of fuel for re-boost plus almost a ton of transfer fuel.
Quote from: DGH on 08/22/2014 09:55 amQuote from: docmordrid on 08/21/2014 09:57 pmISTM the problem with CST-100 for COTS-2 is a small hatch and lack of an unpressurized cargo bay like Dragon's trunk. Adding the latter would have to be a service module extension, and that would cover the circular solar panel at its bottom. It would also add even more mass, perhaps requiring at least one more $RB.Seems by using an expensive, disposable service module instead of integrating it like DV2 & DC they've painted themselves into a corner.My $0.02I do not get this fascination with unpressurized cargo.There is no indication that NASA needs a lot of it.The retiring ATV has no unpressurized cargo capability.Volume and re-boost are its two big features.The current ATV caries over 4 mt of fuel for re-boost plus almost a ton of transfer fuel.Don‘t underestimate the importance of CST00 being able to boost the ISS, as of now NASA are totally reliant on Progress. With no LAS needed a cargo CST00 propulsion module can carry substantially more fuel, only limitation being LV payload.
The problem, as has been discussed to death elsewhere, is the direction and strength of that thrust. If the CST-100 is docked where the Shuttle used to be, it cannot pull the ISS because the exhaust from the thrusters would impinge on the station itself. It can only push the ISS if the station is spun around to face the opposite of its normal direction (American end towards the direction of the orbit).The strength is another matter. You can't have a brute force rocket like a LAS doing the work, as the ISS wasn't designed to handle such accelerations, or such force being transmitted through the docking adapter.
Point 1. Since when is this a problem? This (rotation of ISS for reboost) always happened for Shuttle reboosts. ISS will also change attitude for some docking events.Point 2. The LAS engines - being liquid - can be throttled. But if that is insufficient, CST-100 has several RCS thrusters that can do the job. (presuming they use the same propellant source)
Quote from: Lars_J on 08/22/2014 04:25 pmPoint 1. Since when is this a problem? This (rotation of ISS for reboost) always happened for Shuttle reboosts. ISS will also change attitude for some docking events.Point 2. The LAS engines - being liquid - can be throttled. But if that is insufficient, CST-100 has several RCS thrusters that can do the job. (presuming they use the same propellant source)(1) Depends on how much a pain in the neck doing that flip is. It would have been less of a problem when the station was less complete. I find no record of the last shuttle flight having done this, and it would have made sense to do it on that mission, of all missions. Do we know when was the last time the Shuttle reboosted the ISS? In any case, I was under the (perhaps mistaken) impression the Shuttle could pull the ISS because of how far outboard the RCS nozzles were (compared to those of a capsule).(2) Question: It sounds like, from what you're saying, that they did indeed elect to have a pusher escape system for the CST-100? Wikipedia indicated that it was decided upon, but didn't say what they chose. Artwork out on the web shows the service module both with and without nozzles on it.We need some real astronauts on this forum. They would KNOW.
(1) Depends on how much a pain in the neck doing that flip is. It would have been less of a problem when the station was less complete. I find no record of the last shuttle flight having done this, and it would have made sense to do it on that mission, of all missions. Do we know when was the last time the Shuttle reboosted the ISS? In any case, I was under the (perhaps mistaken) impression the Shuttle could pull the ISS because of how far outboard the RCS nozzles were (compared to those of a capsule).(2) Question: It sounds like, from what you're saying, that they did indeed elect to have a pusher escape system for the CST-100? Wikipedia indicated that it was decided upon, but didn't say what they chose. Artwork out on the web shows the service module both with and without nozzles on it.3. We need some real astronauts on this forum. They would KNOW.
About 2... Yes, CST-100 has a pusher escape system. By definition, since it is located in the SM. How else do you think CST-100 would be able to dock to ISS with a "puller" LAS still attached?
Milestones for CCiCap were agreed upon through negotiations between NASA and the CCiCap competitors.