They are supposed to be able to sit on station for a year, so you do a taxi model where you send an extra one up at the beginning and then rotate that one out every 6 months or so.
Quote from: JBF on 04/08/2014 01:37 pmThey are supposed to be able to sit on station for a year, so you do a taxi model where you send an extra one up at the beginning and then rotate that one out every 6 months or so.Leaving each cab driver outside with the meter running, twiddling his thumbs for half a year?
Quote from: eriblo on 04/08/2014 03:05 pmQuote from: JBF on 04/08/2014 01:37 pmThey are supposed to be able to sit on station for a year, so you do a taxi model where you send an extra one up at the beginning and then rotate that one out every 6 months or so.Leaving each cab driver outside with the meter running, twiddling his thumbs for half a year? You send the first one up on automatics.
Quote from: JBF on 04/08/2014 03:38 pmQuote from: eriblo on 04/08/2014 03:05 pmQuote from: JBF on 04/08/2014 01:37 pmThey are supposed to be able to sit on station for a year, so you do a taxi model where you send an extra one up at the beginning and then rotate that one out every 6 months or so.Leaving each cab driver outside with the meter running, twiddling his thumbs for half a year? You send the first one up on automatics.AIUI from baldusis post and elsewhere there is (or will be) a requirement that a backup docking port is available and only two total. If that is the case then the old vehicle must leave before the new one arrives and can not bring the pilot of the new one back down.
[...]If the taxi model is used that will have to be modified to allow a short period of both ports being used.
Quote from: eriblo on 04/08/2014 04:12 pmQuote from: JBF on 04/08/2014 03:38 pmQuote from: eriblo on 04/08/2014 03:05 pmQuote from: JBF on 04/08/2014 01:37 pmThey are supposed to be able to sit on station for a year, so you do a taxi model where you send an extra one up at the beginning and then rotate that one out every 6 months or so.Leaving each cab driver outside with the meter running, twiddling his thumbs for half a year? You send the first one up on automatics.AIUI from baldusis post and elsewhere there is (or will be) a requirement that a backup docking port is available and only two total. If that is the case then the old vehicle must leave before the new one arrives and can not bring the pilot of the new one back down.If the taxi model is used that will have to be modified to allow a short period of both ports being used.
Quote from: JBF on 04/08/2014 04:42 pmQuote from: eriblo on 04/08/2014 04:12 pmQuote from: JBF on 04/08/2014 03:38 pmQuote from: eriblo on 04/08/2014 03:05 pmQuote from: JBF on 04/08/2014 01:37 pmThey are supposed to be able to sit on station for a year, so you do a taxi model where you send an extra one up at the beginning and then rotate that one out every 6 months or so.Leaving each cab driver outside with the meter running, twiddling his thumbs for half a year? You send the first one up on automatics.AIUI from baldusis post and elsewhere there is (or will be) a requirement that a backup docking port is available and only two total. If that is the case then the old vehicle must leave before the new one arrives and can not bring the pilot of the new one back down.If the taxi model is used that will have to be modified to allow a short period of both ports being used.That and the current planning strongly suggest that the taxi model won't be used. That and the fact that NASA got FAA to say that NASA astronauts are more than space participants and thus can actually pilot the craft without being crew vehicle company's employees.
Being designed for 5 people doesn't mean that it will always carry 5 people. How many shuttle flights had fewer than 7 people on board?Boeing has some requirement in mind that means they are designing for 5 (Bigelow, perhaps?), but if NASA only wants 4 on board, there is no problem.
One tweak to the CST-100 design is the addition of solar cells to the base of the service module. Originally, Ferguson said, Boeing designed the spacecraft to be powered entirely by batteries, given its short free flight times—less than a day—to and from the ISS. Adding the solar panels to the base “allows us to tread water from an electrical perspective” and keep the batteries charged.
Commercial crew, Crimea, and CongressQuoteOne tweak to the CST-100 design is the addition of solar cells to the base of the service module. Originally, Ferguson said, Boeing designed the spacecraft to be powered entirely by batteries, given its short free flight times—less than a day—to and from the ISS. Adding the solar panels to the base “allows us to tread water from an electrical perspective” and keep the batteries charged.
Quote from: arachnitect on 04/14/2014 11:59 pmCommercial crew, Crimea, and CongressQuoteOne tweak to the CST-100 design is the addition of solar cells to the base of the service module. Originally, Ferguson said, Boeing designed the spacecraft to be powered entirely by batteries, given its short free flight times—less than a day—to and from the ISS. Adding the solar panels to the base “allows us to tread water from an electrical perspective” and keep the batteries charged. Good news, IMO. - Ed Kyle
Quote from: edkyle99 on 04/15/2014 02:07 amQuote from: arachnitect on 04/14/2014 11:59 pmCommercial crew, Crimea, and CongressQuoteOne tweak to the CST-100 design is the addition of solar cells to the base of the service module. Originally, Ferguson said, Boeing designed the spacecraft to be powered entirely by batteries, given its short free flight times—less than a day—to and from the ISS. Adding the solar panels to the base “allows us to tread water from an electrical perspective” and keep the batteries charged. Good news, IMO. - Ed Kyleyes, a very good move on Boeing's part to add margin
I hope the CST-100 has oxygen to go with the extra flight time.I assume that the solar panels increase the number of and size of the launch windows.
Quote from: Prober on 04/17/2014 03:33 pmQuote from: edkyle99 on 04/15/2014 02:07 amQuote from: arachnitect on 04/14/2014 11:59 pmCommercial crew, Crimea, and CongressQuoteOne tweak to the CST-100 design is the addition of solar cells to the base of the service module. Originally, Ferguson said, Boeing designed the spacecraft to be powered entirely by batteries, given its short free flight times—less than a day—to and from the ISS. Adding the solar panels to the base “allows us to tread water from an electrical perspective” and keep the batteries charged. Good news, IMO. - Ed Kyleyes, a very good move on Boeing's part to add margin Yes but it is a trade - components like arrays generally add significantly to the failure modes in risk assessments. And it will add significant recurring costs. Engineering is all about choices
I think it goes both ways, here. Not contradicting what you said, just expounding on the comment from Ferguson: CST-100 may retain enough battery power to do the whole mission (in a slightly accelerated mode) with batteries-only if BOTH arrays fail to open, like was discussed with cargo Dragon.