pfdietz

24 ms·

631.
by pfdietz 5mo ago
And all but rather short ballistic trajectories (well below orbital speed) will come in at a steep angle. Unless one has seriously variable aerodynamics, the vehicle will have to swerve to nearly horizontal over a distance of about 1 scale
632.
by pfdietz 5mo ago
No, it's an issue for most arcing trajectories. Lift doesn't help much if you're coming in at a steep angle. Reentry from orbit only works well because the entry is almost flat; there even a little lift helps a lot.
633.
by pfdietz 5mo ago
And here's the thing
634.
by pfdietz 5mo ago
Unless a suborbital trip is nearly at orbital velocity, it will involve a high, arcing trajectory. This will make the deceleration at the end unacceptably (lethally) high for all but short arcs. Some of the Mercury suborbital missions inv
635.
by pfdietz 5mo ago
Ramjets are limited in the speed they can operate because slowing the air to subsonic speed in the engine causes it to become hot, and the temperature increases rapidly with speed (the kinetic energy of an incoming air parcel is proportiona
636.
by pfdietz 5mo ago
There have been air-to-air missiles using rocket-ramjet combinations: they start as a rocket, then once up to speed an inlet opens and they transition to ramjet mode (using the same chamber and nozzle). It extends range. Ramjets are best
637.
by pfdietz 5mo ago
You might try Common Lisp instead.
638.
by pfdietz 5mo ago
Since MMA is used in bone cement for hip replacements, it can't be all that toxic.
639.
by pfdietz 5mo ago
Acrolein is about 300x more toxic than methyl methacrylate in rats. Was this unfortunate victim exposed to acrolein?
640.
by pfdietz 5mo ago
The LD50 of methyl methacrylate in rates is 7-10 g/kg. In comparison, the LD50 of table salt in rats is 3 g/kg. So it's not a highly toxic chemical.
641.
by pfdietz 5mo ago
The problem with that is sometimes it's not clear if something is a constitutional violation. Here, it was clear, but in general you don't want to do that. Something that should be exempt from qualified immunity are actions tha
642.
by pfdietz 5mo ago
That town now has not just a bad water problem, but a large free speech lawsuit problem. Maybe they could dock the Chief's retirement account?
643.
by pfdietz 5mo ago
There are only two elements below the actinides that have no stable isotopes (technetium and promethium). I include bismuth as stable even though technically it is radioactive with an extraordinarily long half life.
644.
by pfdietz 5mo ago
> No matter how cheap they manage to make SpaceX launches realistically, there's really no situation that a space datacenter makes any sense compared to putting datacenters in, for example, Antarctica. Solar energy is going to expen
645.
by pfdietz 5mo ago
I disagree! It's a vital problem to solve, especially if solar becomes significantly cheaper than wind (as appears to be happening; solar has the better experience rate). And solving it punctures one of the last arguments bad-faith
646.
by pfdietz 6mo ago
(2007)
647.
by pfdietz 6mo ago
Are you talking about magnetic reconnection? It's not in violation of physical law.
648.
by pfdietz 6mo ago
These are too expensive for seasonal storage.
649.
by pfdietz 6mo ago
> Still, if it could be stored stably in the summer and converted to heat in the winter then possibly helpful. The capex per unit of stored energy in undoubtedly far too high for that to be worthwhile. Seasonal energy storage requires
650.
by pfdietz 6mo ago
> 'All models are wrong, but some are useful.' And beyond that: models become most interesting at the point they fail, because that's where you learn something.
651.
by pfdietz 6mo ago
Uncle Rodney has left the crankcase.
652.
by pfdietz 6mo ago
The chemical differences are how deuterium isotope separation is performed. This used to be the Girdler sulfide process, now it's catalytic exchange stacks using the exchange of hydrogen isotopes between molecular hydrogen and water.
653.
by pfdietz 6mo ago
> someone else did provide evidence Some 16 minutes after he asked the question, so that's not an excuse for criticism of the question.
654.
by pfdietz 6mo ago
How dare he ask for evidence!
655.
by pfdietz 6mo ago
Imitating your own utter lack of explanation or evidence?
656.
by pfdietz 6mo ago
You're welcome!
657.
by pfdietz 6mo ago
The conspiracy theory mindset, is there anything it can't explain away?
658.
by pfdietz 6mo ago
Indeed, the theoretical argument for hydrogen vehicles did end up being silly. But it's important to understand what it was, if only to help one avoid mistakes like that in the future.
659.
by pfdietz 6mo ago
I already addressed that point. The chlorine concentration is quite low, so the reactive methyl radicals will react with oxygen first. This is unlike the industrial synthesis of chlorinated derivatives of methane, where methane and chlori
660.
by pfdietz 6mo ago
In its defense, hydrogen cars would use fuel cells, not the IC engine of CNG cars. So there's at least a theoretical case that could be made for them. In practice it didn't work well at all. The case for BEVs becomes even more c

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