If the ISS is 180 degrees out of phase only some kind of magic propellantless propulsion is going to allow you to reach it in a few hours.
This picture and the sight of the expanding flame during launches got me thinking, and I know nothing about it, what if the middle engine was replaced with a truncated spike? Could it perform a bit like an aerospike engine? Could it raise the overall ISP by even a nudge?
Not sure if this picture has been posted elsewhere, so in case it hasn't ....
Quote from: dror on 02/25/2015 05:19 pmThis picture and the sight of the expanding flame during launches got me thinking, and I know nothing about it, what if the middle engine was replaced with a truncated spike? Could it perform a bit like an aerospike engine? Could it raise the overall ISP by even a nudge? Not really helpful as you'd lose about 147,000lbs of thrust which you need on takeoff It WOULD perform "like" an aerospike because that's what it would be and there'd be some ISP improvement in general but no where near enough to make up for the lost thrust Randy
Quote from: RanulfC on 02/25/2015 05:45 pmQuote from: dror on 02/25/2015 05:19 pmThis picture and the sight of the expanding flame during launches got me thinking, and I know nothing about it, what if the middle engine was replaced with a truncated spike? Could it perform a bit like an aerospike engine? Could it raise the overall ISP by even a nudge? Not really helpful as you'd lose about 147,000lbs of thrust which you need on takeoff It WOULD perform "like" an aerospike because that's what it would be and there'd be some ISP improvement in general but no where near enough to make up for the lost thrust RandyNot to mention, how are you going to land the thing?
Thanks Helodriver. What is IPA? International Pale Ale? It's between E9and E8
What if they used an aerospike engine on the second stage and it served double duty as a heat shield for second stage return? Would that affect overall performance?
Has anyone heard anything about NASA directing SpaceX to redesign Dragon to be able to carry water for the ISS? This was the first I've seen about it:http://spaceflightnow.com/2015/01/15/nasa-hopes-to-replace-cargo-lost-on-antares-failure-this-year/QuoteGerstenmaier said the Antares launch failure proved the value of having at least two suppliers capable of sending cargo to the space station. It also shows why NASA selected two companies — Boeing and SpaceX — to fly astronauts to the complex.“You don’t put all your critical spares on one vehicle,” Gerstenmaier said. “If you can split between two vehicles or three vehicles, from a redundancy standpoint then you can effectively utilize your redundancy.”He said NASA already directed SpaceX to redesign its Dragon cargo capsule to carry water to the space station, a capability that only Orbital’s Cygnus spacecraft was previously able to handle.“We thought we had enough redundancy so we didn’t have to make design changes to carry water on both vehicles, but now, in hindsight, we need to make a design change,” Gerstenmaier said. “We accepted some non-redundancy items to keep costs down, now we know we need that redundancy.”How does that work exactly? Is NASA on the hook to pay for any vehicle changes they request? It would be one thing if Elon said, "Hey, we're changing Dragon a bit so that it can freight water to the station." But, if the article is to be believed, Gerstenmaier said NASA is ordering it. Does the CRS contract allow them to do so? Does it have a mechanism to deal with the costs of changing the vehicle to meet new customer requirements?I think it's a good idea btw.
Gerstenmaier said the Antares launch failure proved the value of having at least two suppliers capable of sending cargo to the space station. It also shows why NASA selected two companies — Boeing and SpaceX — to fly astronauts to the complex.“You don’t put all your critical spares on one vehicle,” Gerstenmaier said. “If you can split between two vehicles or three vehicles, from a redundancy standpoint then you can effectively utilize your redundancy.”He said NASA already directed SpaceX to redesign its Dragon cargo capsule to carry water to the space station, a capability that only Orbital’s Cygnus spacecraft was previously able to handle.“We thought we had enough redundancy so we didn’t have to make design changes to carry water on both vehicles, but now, in hindsight, we need to make a design change,” Gerstenmaier said. “We accepted some non-redundancy items to keep costs down, now we know we need that redundancy.”
Quote from: Tass on 01/16/2015 10:33 amHow does that need a redesign? It can transport all that other stuff. Couldn't they just put some containers in there?The work (and the cost associated with it) is not for the water redesign per-se.Its mostly for paperwork, to document and certify how the (probably bags of) water will be stowed, secured and moved in and out, and to ensure safety, mass-distribution, leak risk and handling etc.When the mass of the paper > the mass of the water, they'll be good to go
How does that need a redesign? It can transport all that other stuff. Couldn't they just put some containers in there?