Quote from: M129K on 01/09/2014 03:15 pmQuote from: Elmar Moelzer on 01/09/2014 03:11 pmQuote from: Lars_J on 01/09/2014 06:24 amI find the idea that DC would be too heavy for Ariane V to be very bizarre.As do I...Too big =/= too heavy.Lars and I were referring to this:Quote from: Chris's articlebefore adding he thinks the Dream Chaser is currently a little bit too heavy for the launcher.
Quote from: Elmar Moelzer on 01/09/2014 03:11 pmQuote from: Lars_J on 01/09/2014 06:24 amI find the idea that DC would be too heavy for Ariane V to be very bizarre.As do I...Too big =/= too heavy.
Quote from: Lars_J on 01/09/2014 06:24 amI find the idea that DC would be too heavy for Ariane V to be very bizarre.As do I...
I find the idea that DC would be too heavy for Ariane V to be very bizarre.
before adding he thinks the Dream Chaser is currently a little bit too heavy for the launcher.
The Atlas first stage isn't a sustainer stage, and Centaur does a lot of the ∆V to reach orbit. The Ariane core almost reaches orbit and the ES upper stage only performs a small, 100-200 m/s burn on LEO flights. Are you sure DC isn't capable of that?
Quote from: M129KThe Atlas first stage isn't a sustainer stage, and Centaur does a lot of the ∆V to reach orbit. The Ariane core almost reaches orbit and the ES upper stage only performs a small, 100-200 m/s burn on LEO flights. Are you sure DC isn't capable of that?100-200 m/s? For a 20t payload a little calculation gives me 1228 m/s.
Ariane 5 is mass-limited to LEO because it's designed as a GTO launcher.I don't know what the ME version will be able to carry but the ES version they currently use for ATV and which has structurally reinforced first stages is no longer around, it got discontinued long ago when they knew they're going to stop ATV. That might be what they need to fix, they probably still know how to do it but it will come at a cost.
Quote from: aquanaut99 on 01/09/2014 04:04 amSo, is this the resurrection of Hermes?.. with similar capasity, much much lower mass. What I'm missing here?Dreamchaser is something like 11 tonnes, hermes was getting too heavy for ariane V which could lift something like 20 tonnes. Both have similar class of capasity. How is dream chaser so much lighter?
So, is this the resurrection of Hermes?
Isn't ITAR going to be a problem for Europeans? For instance if they want to refurbish the craft themselves between launches?
Quote from: hkultala on 01/09/2014 04:26 amQuote from: aquanaut99 on 01/09/2014 04:04 amSo, is this the resurrection of Hermes?.. with similar capasity, much much lower mass. What I'm missing here?Dreamchaser is something like 11 tonnes, hermes was getting too heavy for ariane V which could lift something like 20 tonnes. Both have similar class of capasity. How is dream chaser so much lighter?It's smaller.
Quote from: manboy on 01/10/2014 02:27 amQuote from: hkultala on 01/09/2014 04:26 amQuote from: aquanaut99 on 01/09/2014 04:04 amSo, is this the resurrection of Hermes?.. with similar capasity, much much lower mass. What I'm missing here?Dreamchaser is something like 11 tonnes, hermes was getting too heavy for ariane V which could lift something like 20 tonnes. Both have similar class of capasity. How is dream chaser so much lighter?It's smaller.That and the original Ariane V had less performance. An Ariane V could probably put 23tonnes to 25tonnes on LEO.
Quote from: gosnold on 01/10/2014 08:51 amIsn't ITAR going to be a problem for Europeans? For instance if they want to refurbish the craft themselves between launches?I am not an expert on ITAR but I don't think that SNC would sell a DC to ESA. They would rent it and SNC (or one of their U.S. subcontractors) would operate it. I believe that there are efforts to remove spacecrafts from ITAR. But that has yet to be done.
Quote from: yg1968 on 01/10/2014 01:19 pmQuote from: gosnold on 01/10/2014 08:51 amIsn't ITAR going to be a problem for Europeans? For instance if they want to refurbish the craft themselves between launches?I am not an expert on ITAR but I don't think that SNC would sell a DC to ESA. They would rent it and SNC (or one of their U.S. subcontractors) would operate it. I believe that there are efforts to remove spacecrafts from ITAR. But that has yet to be done.Well it would seem to go against the ESA "buy european" policy then. I was thinking DLR might buy a DC on its own funds (no political problems with ESA in this case) and then ESA could operate it with european industries doing the maintenance/refurbishment. But it is too early to tell anyway.
At the end of an initial evaluation and planning phase, which will continue through 2014, the organisations expect to continue the relationship through a long-term agreement leading to flight operations. Both entities foresee further arrangements to continue the partnership towards the potential use of Dream Chaser for European missions.
Named DC4EU (Dream Chaser for European Utilization), the project is to explore ways in which the Dream Chaser®can be used to cover German and European requirements for the transportation of payloads and astronauts to the International Space Station (ISS) and for deployment as a manned or unmanned space vehicle allowing German and European scientists to conduct research under weightless conditions over extended periods of time. Given the capability which the Dream Chaser® has for reaching orbits at a substantially greater altitude than the ISS, the study will determine the extent to which it is able to supply satellites or remove decommissioned satellites from their orbits.
Quote from: adrianwyard on Today at 03:45 PM I am not sure if ESA ever had in mind to upgrade their Soyuz launch facilities for ESA manned flights...
Quote from: Oli on 01/09/2014 07:39 pmQuote from: M129KThe Atlas first stage isn't a sustainer stage, and Centaur does a lot of the ∆V to reach orbit. The Ariane core almost reaches orbit and the ES upper stage only performs a small, 100-200 m/s burn on LEO flights. Are you sure DC isn't capable of that?100-200 m/s? For a 20t payload a little calculation gives me 1228 m/s.After rechecking myself, it gave me about 600 m/s. The EPS is short fueled for ATV missions to about 5 tons I believe. Anyway, this could very well be because ATV doesn't have the thrust to make a circ burn on it's own, forcing an upper stage to be used, and it only gives that much delta V because it is optimized with a ~5 ton prop load. DC doesn't have this thrust problem and doesn't have to require an upper stage for insertion, so it's possible the Ariane core does more of the burn to orbit. This would reduce payload of course, but if an Atlas V 402 can lift it into orbit, it shouldn't be that much of a problem.