wb
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Post by wb on Sept 26, 2016 17:17:46 GMT
Elon Musk just tweeted details of the first Raptor engine firing and design specifics, so lets try to make it in CODE!  Nozzle diam. ~4.2 meters Effective exhaust vel 3746 m/s Chamber press. 30 MPa Apparently this means a pump discharge pressure around 50 MPa |
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wb
New Member
Posts: 8
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Post by wb on Sept 26, 2016 17:36:30 GMT
This is my best so far:  How can I reduce the thrust but increase the Isp? I'm sure the materials are wrong too but that doesn't really matter since we don't know what the weight should be. |
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Post by domfluff on Sept 26, 2016 18:25:50 GMT
Just unlocked the module designer. This game is insane.
RC-C is probably right for the chamber walls - we know that's something SpaceX is pursuing. Iconel would be the other plausible option, which I think is Nickel-Chromium-Iron?
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wb
New Member
Posts: 8
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Post by wb on Sept 27, 2016 5:38:53 GMT
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Post by cardshark on Sept 27, 2016 22:04:22 GMT
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wb
New Member
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Post by wb on Sept 28, 2016 4:21:39 GMT
Of course, but they forgot the rail guns! What an oversight! |
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Post by mikeck on Oct 2, 2016 18:21:49 GMT
And the food, water and supplies. When asked what the colonists would do for food and water on the long flight to Mars AND once they get there he said something like "yeah, well there will be something there...we will figure something out "
As if water and food isn't mass
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Post by Autochton on Oct 3, 2016 6:26:43 GMT
As if water and food isn't mass Two words: cargo ship. To elucidate a bit, the ITS is largely autonomous, and so adding a number of cargo vessels to the fleet, carrying things like inflatable temporary habitats, industrial equipment for bootstrapping the colony, extra food and growing equipment, etc. only makes sense. The intent is for a colonization fleet, not a single-ship excursion. |
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Post by mikeck on Oct 4, 2016 21:19:06 GMT
That would work for long term but the question was in reference to traveling to Mars and the required water and food. I'm not saying it can't be done. I'm just saying that people tend to criticize NASA for not coming up with a plan it's easy to come up with a broad plan when you don't have to worry about details
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Post by nivik on Oct 4, 2016 21:51:18 GMT
That would work for long term but the question was in reference to traveling to Mars and the required water and food. I'm not saying it can't be done. I'm just saying that people tend to criticize NASA for not coming up with a plan it's easy to come up with a broad plan when you don't have to worry about details Well, for water, recycling is an option. That helps significantly. For food, I'm doing some back of the cuff calculations based on this: www.amazon.com/Eversafe-MRE-Pallet-48-Cases/dp/B00DNHYQZ2 -- which is not optimized for people Assuming the lower figure there, each pallet of MREs provides 576000 kCal for every 990 lbs (450 kg). That comes to 1280 kCal per kg. Human requirements differ, but roughly 2kg average per day per person should do it (2560 kCal). Musk said that the ship will be designed to transport 100 people, so we'll need 200 kg per day. According to this -- image.gsfc.nasa.gov/poetry/venus/q2811.html -- a minimum delta-V transfer will take around 260 days. 260 * 200 = 52,000 kilogams, or 52 metric tons. According to en.wikipedia.org/wiki/Interplanetary_Transport_System, the ITS is designed to transport 450 metric tons of cargo and passengers to Mars. The passengers should only average about 8 metric tons, plus personal effects, so even with a 100% safety margin on food, that leaves 338 tons for water (which will almost be recycled), oxygen, and cargo. So, I think it's still plausible, particularly since MREs have a huge amount of packaging involved and there's probably room for mass optimization there. |
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Post by pokington on Oct 5, 2016 1:59:23 GMT
So, I think it's still plausible, particularly since MREs have a huge amount of packaging involved and there's probably room for mass optimization there. Speaking from experience, they are about 50% packaging by mass, and most contain hydrated foods, so yeah, they can be optimized. While they've gotten better in the last 8 years, I still might space myself after eating nothing but MREs for 6 months, if I didn't just wear out my entire digestive system and die from that already. |
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Post by dwwolf on Oct 10, 2016 9:21:36 GMT
Theyve invested alot more in astronauts, so they also invest alot more in astronaut food  |
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Post by harlikwin on Oct 10, 2016 23:05:39 GMT
Yeah, I think they would have fatalities after only eating MRE's for a few months.... MONTHS.... I don't think most people know how "great" eating only MRE's for a week or two is... MONTHS, YEARS....
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Post by nivik on Oct 11, 2016 16:13:11 GMT
Yeah, I think they would have fatalities after only eating MRE's for a few months.... MONTHS.... I don't think most people know how "great" eating only MRE's for a week or two is... MONTHS, YEARS.... XD I was just using it as an example of a long shelf-life prepackaged food, to show plausibility. Realistically, you'd want to include frozen foods as well. Astronauts do okay for meals currently on 6-month (and longer) missions, so I don't think it'll be a problem. I just wanted a (pessimistic) mass estimate for the required calories. |
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