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#11
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CRS-11 is on its way
JF Mezei wrote:
On 2017-06-07 06:20, Jeff Findley wrote: No, this is not correct. The Dragon "trunk" does not have any propulsion systems. As many systems as possible are packed *inside* the Dragon reentry capsule to be reused on subsequent flights, like this one (CRS-11 is reusing the capsule from CRS-4). Does this mean fuel tanks are also in the Dragon and not in the trunk? What small fuel tanks there are, yes, although I think they've switched over from the 90 lb thrust Draco hypergolic engines to cold gas for OMS engines. I guess my thoughts were tainted by Soyuz and Apollo that had mosts of their systems in the module. Apollo had a Service Module. Dragon does not. The trunk is not just another name for a Service Module. It has a different name because it is a different thing. Note that Orion has a Service Module and not a trunk. Manned Dragon, on the other hand, has a trunk like the cargo variant. Orion has a longer manned duration than Dragon V2 (21.1 days vs 7 days) but Dragon V2 carries a larger crew. It works out to 84.4 man-days for Orion vs 49 man-days for Dragon V2, although presumably support equipment could be added in the trunk to increase flight durations. Either vehicle will need an attached hab module for any long duration missions (both have a docking port). Both would presumably stay attached to a high energy upper stage for long range missions, although both have their own propulsion systems. The Orion Service Module includes a 6,000 lb thrust engine with enough fuel for around 1800 m/s delta-v. The eight Super Draco engines built into the Dragon V2 are capable of delivering more than 100,000 lbs of thrust but only around 400 m/s of delta-v due to not carrying much fuel; there's only enough for around a 25 second burn. Given that the fuel tanks are built into the Dragon, I don't think it would be easy to increase that. So when Dragon needs to accelerate forward, wouldn't engines on Dragon throw hot gases at the solar arrays atached to the trunk ? A child could do a design where that doesn't happen. -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw |
#12
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CRS-11 is on its way
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#13
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CRS-11 is on its way
On 6/4/2017 1:42 AM, JF Mezei wrote:
On 2017-06-03 18:46, Jeff Findley wrote: SpaceX just launched CRS-11 on its way to the ISS and it looks to have been a successful launch and a successful landing of the first stage at LZ-1 (spot on the center of the pad). It's quite a waste to return stage 1 without any payload. I say SpaceX should sell "Virgin Galactic" style joy rides on stage 1 :-) No thanks. I like my cookies eaten, not tossed, pitched, fried or diced... Just ask cowboy Bob... :-) Dave |
#14
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CRS-11 is on its way
On 6/9/2017 1:24 AM, David Spain wrote:
On 6/4/2017 1:42 AM, JF Mezei wrote: On 2017-06-03 18:46, Jeff Findley wrote: SpaceX just launched CRS-11 on its way to the ISS and it looks to have been a successful launch and a successful landing of the first stage at LZ-1 (spot on the center of the pad). It's quite a waste to return stage 1 without any payload. I say SpaceX should sell "Virgin Galactic" style joy rides on stage 1 :-) No thanks. I like my cookies eaten, not tossed, pitched, fried or diced... Just ask cowboy Bob... :-) Dave https://cdn.vox-cdn.com/assets/1916727/cowboyspacex.jpg |
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