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Comment: Re:I wrote the article! (Score 1) 236

by baldusi (#46443019) Attached to: SpaceX Wants To Go To Mars — and Has a Plan To Get There

Fluoride is impossible to run oxidizer rich, to drive the turbopump. The Raptor is gas gas. So you need to preburn both fuel and oxidizer. Abd here is where CH4/LOX combo shines. Turbine power is, for a given input and outlet temperature, mass flow * specific heat. RP-1 can't be run fuel rich at staged combustion pressure and heat. H2 is great, but it had 14 vs 0.9 for LOX. Since O/F is 6.0, you have too much power on the H2, and too little in the LOX side. But CH4 has about 2.1 with an O/F ratio of 3.2. So your power is very balanced and you can push the system a 50% more.
Either 50% more chamber pressure for crazy performance or 35% lower temperature for longer life, higher reusability.
Lastly, if you take 1kg of H2 to mass, you'd be able to make more than twice the propellant if you mix with CO2 to make CH4 through the Sabatier process, than if you simply extracted the O2 to make the LOX. Not to mention that CH4 is way easier to store than H2 while you produce your propellant and wait for the craft to arrive.

Comment: Re:I wrote the article! (Score 1) 236

by baldusi (#46442953) Attached to: SpaceX Wants To Go To Mars — and Has a Plan To Get There

The are many parameters. H2/F2 has the highest specific impulse of bipropellants. But nobody works with F2 because is a nasty chemical. Not to mention the ecological consequences
But even using LOX as an oxidizer, H2/LOX uses 3 times more volume than RP-1/LOX. That's three times more tank mass. But H2 need to stay under 20K, while LOX 89K and CH4 100K and RP-1 above 250K or so.
And that is quite an issue. You simply can't have zero boiloff on H2 without a cryocooler. LOX and CH4 can be done passively. RP-1 needs an easy heater. But doing passive LOX at 89K while keeping RP-1 at 250K needs to keep the tanks seprated. Thus, it's heavy and you have two different systems.
CH4/LOX is done passively and can be done with a common bulkhead, which is the most efficient construction and has the least failure modes.

Comment: Re:I wrote the article! (Score 3, Informative) 236

by baldusi (#46439931) Attached to: SpaceX Wants To Go To Mars — and Has a Plan To Get There

Sorry for the dupe, I forgot to login.
Oh, the reason is very technical. The short story is that CH4/LOX is the best on full flow staged combustion. Exactly the most difficult and expensive cycle that nobody wanted to do. And if they do, since handling a new propellent is a new development in itself, they rather do with the propellents that they know.
In the staged combustion level, CH4 is slightly better than RP-1/LOX, if you have Russian efficiency, else RP-1 is better. But if you have an hydrogen/LOX upper stage is inferior. And since it need 27% more volume than RP-1/LOX, if you are volume limited (like everybody usually is, due to road or train transport limitations), RP-1/LOX is better. And for reusability, it depends on the parameters. Hydrogen can work, and NASA, Rocketdyne, P&W and Aerojet (now, all the same company), had a lot more experience in H2 and might be a better choice for Shuttle like applications. And if you compare to hypergolics (think Proton, Long March, etc.), hydrogen or kerosene, it is more difficult to start.
And again, all this for a first stage, space applications might have different requirements.
So, methane is king for a first full flow reusable engine. Which should be the pinnacle of performance, but nobody had boldly gone there.

Comment: I wrote the article! (Score 5, Interesting) 236

by baldusi (#46437891) Attached to: SpaceX Wants To Go To Mars — and Has a Plan To Get There

Glad that yoy liked it. That engine is an enabler. Methane/oxygen works incredibly well in gas-gas cycle. It's unbeatable for that.
What I can tell is that Elon is serious in his desires. But you have to understand that the reason for that is that he has the vision and he's actually doing an ambitious but realistic plan. Next week flight will have legs on the first stage. And they'll try to pin point land it on the sea. If they do, the guys at the Cape with the big red button might let them try to land it in US soild next. But if not, that's still the cheapest rocket in its category in the world. Their modus operandi is realistic and bold. We'd better follow him because we might be watching history in the making.

Comment: New Coke was about replacing sugar. (Score 1) 786

by baldusi (#43642357) Attached to: Microsoft's "New Coke" Moment?

New Coke was not a blunder. The fact is that Coca-Cola wanted to replace the sugar cane on the recipe with high fructose corn syrup. It's not only cheaper but generates more need to keep drinking (eating) whatever has it. The taste is close enough, but you couldn't switch it overnight without people noticing. Thus, the launched New Coke to have a few months between batches, so people wouldn't notice ti taste difference. After all, they wanted the Old Coke to taste the same old.
It worked quite well, btw.
Win8 might have been quite the same strategy, but the question would be what's the Microsoft high fructose corn syrup? I don't think they are that clever.

Comment: Re:why the obession with glider spacecraft? (Score 1, Interesting) 127

by baldusi (#32933180) Attached to: Germany To Test Actively-Cooled Spacecraft

Because the USAF wanted the Shuttle to be able to use the atmosphere to break and turn back. This way, when launched in a polar orbit, it would be able to turn back and capture GLONASS or Russian Spy Satellites without appearing on the russian radar. Of course, the final design wasn't able to do such a manouver so the USAF has no use for it. But the design stick.

Comment: It's not a plagiarism bill, actually. (Score 5, Informative) 165

by baldusi (#32210186) Attached to: In Argentina, Law Against Plagiarism Plagiarized

I live in Argentina and have read the original proposal. In fact he's proposing to up the penalties for misrepresenting, selling fake property as the original or selling property without that you don't own. Basically, you could sell fake goods, but you'd have to state it, thus, you'll be infringing on copyright. It's not so much about plagiarism as about misrepresentation and selling of fake goods as originals.
Having said that, I still think what he did was despicable and I seriously doubt his wits to be a representative. But which country is proud of its politicians? I would seriously consider moving there!

Comment: Re:They're black! (Score 1) 192

by baldusi (#31579248) Attached to: Quantum Film Might Replace CMOS Sensors

The main problem was on the wide angle side. The long lenses are amazing. They released a 24mm f1.4 II with the 5D mkII because it was soft. Ditto with the 14mm f/2.8 II vs. I. And the new TSE 24mm f3.5 II is head and shoulders over the original. Just consult http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?FLI=0&API=0&FLIComp=0&APIComp=0&LensComp=0&CameraComp=0&Lens=404 and see for yourself. Obviously the 200mm f2.0 is just unbelievable and the 200mm f4.0 IS is incredibly sharp. But the 200mm f2.8 IS was soft and lacked contrast when wide open. Just compare the just released II.
In general the wide old glass didn't resolved enough at 21Mpx FF.

Comment: Licenses. (Score 2, Informative) 17

by baldusi (#31187586) Attached to: Free Netbook From Microsoft, Then Things Got Weird

Unless he uses Linux, FreeBSD or any other OSS, he's exposing himself to infringing on Microsoft copyright (how can that be penalized more heavily than physical robbery, is beyond me).
And he has just make a very public questioning of the legality of his software ownership.
I do think he should press to get proper licensing. How does he knows that it was properly activated and it's not a crack? WPA itself has lots of false negatives as it is.

When someone says "I want a programming language in which I need only say what I wish done," give him a lollipop.

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