wumpus

With nVidia beating the drums for raytracing, I've been assuming that Unity would benefit most from raytracing. Mostly because I don't expect developers using Unity to spend a lot of time writing shaders (although some modders do), but simply slapping in a "raytrace this spacecraft" would pretty much fix all the shading (if the GPU is up to it). Of course, this requires Unity to make a huge move, followed by a move on Squad's part to the upgraded Unity as big as moving to 64 bit or the move to Unity 5 and multithreading. Hopefully it won't need a move to 2.0 and will just be folded in to the 1.x line.

One thing to consider is how the vectors line up. Thrust produces a force prograde to your rocket. Gravity produces a force equal to your weight towards the CoM of the planet beneath you. For planets with an atmosphere or cases where your TWR is relatively low, you have to start pretty much straight up. It should be pretty clear that for normal (nowhere near suborbital flight), any model rocket launched straight up will go higher than one launched at an angle. It is only when the sum of the vectors start to "miss the planet" that going sideways really begins to help (that and the Oberth effect thanks to the larger overall magnitude of the combined force). For something like Minmus, I think you can use wheeled takeoff and landing on the "seas" for optimum direction (just make sure you miss any slopes/mountain ranges).

Fuel flow rate should be constant regardless of atmospheric pressure. I'd think that exhaust velocity varies with atmospheric pressure, thus reducing Isp at significant pressures. In any case the amount of delta-v per amount of fuel is significantly reduced in atmosphere. Note that this is completely different from the pre-release model where Squad would increase fuel flow to directly decrease Isp while leaving thrust constant. The current model is more or less how it really works (although don't expect miracles from nozzle simulation as it passes through the atmosphere).

Try one of these: https://www.space.com/21867-cubesat-deep-space-propulsion-kickstarter.html That said, I doubt this would shave off much of the initial delta-v needed to go to Pluto, nor have the delta-v needed to slow down for gravitational capture. My understanding is that scaling up ion thrusters is the problem. I'd expect that they scale down fairly well.

Wiki claims Delamar [Dry] Lake Landing Strip was "designated as an emergency landing site for the X-15", but from memory the test flights intentionally landed there as well. In the wiki it mentions that they dropped the X-15 while over the lakebed, so presumably if the engines didn't fire (or weren't planned to fire like the first few tests), they would land on the lakebed. So this type of thing was hardly unusual for early space flight. On the other hand, I'm pretty sure you would have to build landing strips near KSC [the one in Florida]. Any long flat surface will typically be covered with water unless intentionally built up as runway. But using natural runways is hardly breaking realism.

I was watching far too much of that video and realizing that he was arguing *for* [foveated] VR, and not "against 4k". A better reason to avoid 4k is that it either needs to expand to the size of your wall (shades of Farenheit 451) or you have to sit far too close to see it. Of course, if somebody wants to subsidize my next monitor and create a mass market for a 4k monitor in the 30-40" range, I am perfectly happy with that.

This thread included way to much data on lasers. I don't think it covers the atmosphere, but should describe how a laser would disperse over such distance (I thought this was besides the point, so didn't read it carefully even when it was posted). To find information on how much a laser scatters through atmosphere, look up light scattering into (uncorrected) telescopes. From (multi-decades old, not to be trusted) memory, the best resolution increase of an uncorrected telescope was roughly the same as a 30cm (diameter) telescope, after that the atmospheric issues negated the power of the telescope to increase resolution (but bigger telescopes were still made at the time to collect faint light).

Python used to be the best language out there for handling strings, although this likely was sacrificed in favor of unicode during the change from 2.x to 3.x. C's original method of string handling was not particularly good and lead to completely insecure code and had to be completely depricated. You might even flee to C++ string handling, but expect that even thinking about touching C++ features have side effects upon side effects to those who never learned the details of C++. - leaned C++ from library books. - It took me weeks to find the bug in my just-beyond-trivial routine I needed to use a C++ library in my python - the library books didn't bother to teach required keywords ("new" was one) that were needed to use programs with subroutines (i.e. any non-toy program, and most toy ones at that). - won't touch the thing anymore, but might have to check my wrapping again soon.

Much like the cost of the fuel of the rocket, the cost of the railgun is so high the cost of the electricity will always be in the noise (probably less than maintenance of the railgun). It is a weird concept to ignore the fuel used in something that is 95+% fuel, but that's how rocket economics work. But to answer your question I'm sure it is more efficient for higher delta-vs (where the electricity is pushing a constant mass vehicle and the extra-methane rocket has to accelerate the extra methane as well), not sure for values just breaking the transonic area. If you actually built such a thing there's always the danger that somebody would build a beanstalk and simply take all your business, probably long before you paid off the skyramp and started to worry about the electricity. - I strongly suspect that any spacecraft that has wings and not using air-breathing engines is doing something wrong (a skyramp might be ideal for a first stage followed by a second stage ramjet. But I'd assume that such a craft also needs a rocket engine, and why not fire that first as well?): X-15: most missions didn't go into space Shuttle: Best way to land in the 1970s, generally the best solution to too many bad specifications, but still didn't produce a good spacecraft for the time Burran: A very expensive way to learn that the Americans (mostly in Congress) didn't know what they were doing Space Ship One: just touched space, was an airplane the other 99% of the time.

I don't doubt that, but it must be easier to build a second nozzle than to try to wring out more than twice as much power from hydrogen expansion. Especially if you want to try to relight it (I suspect much of RL-10's cost is needing two sets of turbopumps just to get it started). Russian designs use multiple nozzles for kerolox rockets and this seems to help with other issues as well.

In that case the slightly larger rocket with extra methane+liquid oxygen will win for less than 100-1000 reuses. And getting down to 1000 reuses assumes much cheaper vehicles, and might really take 10,000 launches. Things get even worse if somebody decides that air-augmented rockets or other airbreathers make sense before you build your skyramp. Nobody has really built a high-volume means to get into space (although block 5 appears to be getting there), so we really don't know what's most efficient, or even what the requirements are.

The BE-3 wiki still says "490 kN thrust', while the RL-10 says "110 kN thrust". The only way you are getting an expander cycle engine up to 490kN is with at least* 4 nozzles (and we see only one in the tweet). They say that two is enough, I'm wondering if there is a plan to give each BE-3U two nozzles to allow higher thrust. * maybe less nozzles, but expander cycles have hard limits for how much thrust/(nozzle+combustion chamber) and it can't be that higher than RL-10.

Electrolysis is ghastly inefficient and the Sabatier reaction reaction would only ruin your Isp to get better thrust at a significant cost of electricity. Then there's the whole issue of thermodynamic efficiency of the thermal rocket cycle (which might be saved thanks to extreme hot/cold delta, I don't know). I think even a railgun is more efficient than heat engines, imagine the efficiency of an electric car if it didn't have to carry batteries around. The real problem is that now you are fighting the rocket equation. For low thrust rockets (which make even more sense on skyramps), you can burn half your mass in fuel getting to mach 3 and half your mass again to mach 6. Simply using electricity to accelerate a much lighter spacecraft has efficiencies all of its own.

Escape velocity of Sun is ~617 km/s. As close as it gets to the Sun, I'm not sure it can remain orbiting if it isn't going roughly that fast.

The US Navy is trying to replace steam driven catapults with a system called EMALS for electric acceleration. It will get to 150mph, but is so far unreliable (10% failure rate) and is priced at US carrier volumes but is unlikely to hurt anyone who can meet military pilot health checks (might be a problem with the general public but not astronaut crews for some time).

The C++ spec is 1605 pages long. While being able to program in the "pigeon english" equivalent of C++ might take little more than C, being able to parse code using all the features may be as hard as doing the same with a human language. It certainly is an outlier, and its popularity has turned it into the proverbial kitchen sink. I'd recommend Python. Or if you want to get "down to the metal", C (which is probably best for small arduino code). As the introduction to K&R said, "C is not a big language, and it is not well served by a big book". https://www.iso.org/standard/68564.html

Two things about bullroarers. That sound should include subsonics (or at least subsonics are easiest to produce by bullroarers). This is sometimes used in religious ceremonies as the subsonics have been known to evoke divine/supernatural feelings in people. The other is that they were invented by this guy: Who also invented golf.

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There are two issues with taking cryogenics beyond LEO: 1. Boil-off: The traditional means for keeping cryogenics cold is to insulate a little and let the rest simply boil to keep temperature in a liquid state (presumably we can insulate now better than during the Apollo era, but don't expect hydrogen to stick around). 2. Ignition: Cryogenics typically involve turbopumps (which further increases Isp) which need to start and are pretty complex. After that the whole thing needs to be ignited. Considering just how complicated the ignition systems used on Earth are (and the holding clamps needed to wait for all ignition to happen), you are really betting the lives of the entire crew that the rocket can start. Hypergolic engines will always work as long as two values open and neither the fuel nor the oxidizer leaked out. I suspect rocket labs may find their electric turbopump more useful as a beyond-LEO rocket engine than a means for launching cubesats. It has a way to go to prove itself reliable, but I imagine that any rocket that can recharge via the Sun (especially during Pe kicks) and has a lot less turbopump issues will find plenty of buyers.

Yet another example of "technology is infrastructure". You can invent all the gadgets you want, but it won't be important until the infrastructure can build on a large enough scale. It might have taken a little longer for pretty much every technology used in guns (ok, not computer controlled aiming) was available roughly that time (not sure about gas based repeaters, they might take awhile). Similarly cars had pretty much every advance used by the 1920s (there was a hybrid made between 1900-1905, presumably easier to get to work than a clutch. Once the clutch was good enough you wouldn't see hybrids for 90 years), and everything in computers was "invented" 3 times, for mainframes and supercomputers, in minicomputers, and finally microchips. The thing about firearms was that they penetrated armor (obviously this wasn't binary, but the point was they were good enough at it). If a highly trained knight is roughly as likely to be killed as a peasant you could train in a few weeks, it didn't make sense to build your economy around training heavy horsemen as knights. And of course once the king was less dependent on the nobles, he could cut his support of them (and the nobles would be less dependent on the knights, who they couldn't support as well without the King's support, so the knights were really getting squeezed). Still, the whole structure really didn't fall apart until WWI (the noble's power was decreasing, but no real discontinuity until the Marne). Note that as late as the battle of Waterloo the French had cuirassier units wearing breastplates. These were rare elite units, but the armor was said to be good for a fairly long range (there couldn't have been much time between when you could penetrate the armor and when you had to be more concerned about the cuirassier's "sabre" (quotes because the thing really couldn't cut and was used for stabbing). One even more topical thing about the breastplate they wore was that if you were wearing one and anything got through it, you died. Partially because anything that could get through the steel won't be stopped by meat, and partially thanks to all the contaminants bullets and pointy steel things pick up going through the armor and depositing in said meat. One other topical thing (at least for Stone Age tech): trying to push stone (copper? Ötzi the Iceman had a copper axehead) into the iron age requires fireproof gloves. The saying was "God made the first pair" because you needed a pair of gloves to do any ironwork, including making a pair of fireproof gloves. On the other hand you can use a flat rock as an anvil, this was used by the steel-weapon-making Norse in the Viking age (presumably. It was mentioned in the Icelandic Sagas, but written long after the events took place and may have been included to give an "old timey" feeling. I doubt this is the case since I doubt that "technological improvements" was how medieval Icelandic people marked the passage of time).

If it moves, salute it. If it doesn't move, pick it up. If you can't pick it up, paint it (camouflage). Already camouflaged, do not paint.

The tutorials aren't often used, so I don't trust Squad to fix bugs in them. Don't be surprised if many of them aren't completable. I vastly prefer text to video, but Scott Manley's content is sufficiently good to recommend even to those who prefer text. My favorite text is Space Flight by Carsbie Adams, a Sputnik-era primer on space flight for the undergraduate level (anything modern I've seen pretty much assumes a degree in aeronautical engineering, and often more on top of that). At $10 from Amazon used, I'm not sure I'd recommend it, but it gives a great background on basic rocket science and a bit of history of the early space race. Don't ignore career mode. It seems to introduce new requirements in a fairly good order, although I'd recommend visiting Minmus before Mun, and only then attempt to rescue kerbals (rescueing kerbals is a great way to learn the basics of rendezvous and dock, with much lower precision needed for "success". Once you can routinely rescue kerbals I'd recommend strapping RCS to your system and docking). The only real issue with going to Minmus first is that you have to correct your alignment before transiting, but this is typically better than landing on the slopes of the Mun (nevermind the benefits of being able to use the altimeter when landing on the flats in stock, otherwise you need a mod with "altitude over ground"). Career mode may seem a bit grindy a few times, but I suspect it is pretty good for new players - disclosure: I didn't learn in career mode (and it was difficult to the point of buggy in 1.0.0-1.0.2), but way back we had a wiki with "Scenarios" that suggested a basic progression for use in sandbox (the only available mode).

That and allegedly a papal ban didn't stop Richard the Lionhearted from equipping his peasants with crossbows. Henry V loved bringing longbowmen along, and after Agincourt (which proved that peasants could sometime slaughter fully armored knights) most of the rest of the armies demanded them as well (although I think the French stayed with crossbows). Laws were made to ban everything but praying and practicing archery (presumably the fact that this shows up enough in historical documentation shows that it was widely ignored and kings and others interested in maintaining large armies kept trying to enforce it). New weapons tend to be enthusiastically used whenever they show up (if they aren't, then those who don't are "selected against" and all remaining fighters are using the new, improved weapons/tactics/whatever). The only exception seems to prove the rule, as once feudal Japan was unified (and a later invasion of Korea turned unsuccessful), guns were effectively (if gradually) banned. The Shogun felt that neither Korea nor China could invade, and his only rivals were various great lords. So he was more than happy to level the playing field (and his samurai were equally happy to not face guns). By the time Commodore Perry showed up, guns were museum curiosities (even though they were making more and better guns in Japan than Europe during those wars of unification. The only way guns wouldn't take off in Britain would be if there weren't a Saxon invasion going on at the time, they weren't remotely worried about the Welsh and Scottish border (obviously there wouldn't really be a Welsh border for King Arthur), Ireland nor the Vikings weren't a concern, and England and France didn't want each others' territory.

Pretty much. But thanks to Morte de Arthur the tale is pretty much locked into tales including full jousting on horseback complete with the expected armor (heavy plate, presumably with articulated joints). Romanized britons might have had lorica segmentata (mostly metal strips), which might look similar to modern eyes but that is vastly different and never used for jousting. The "Arthur" according to Geoffrey of Monmouth (one of the earliest records) could hardly be recognised as Arthur today, and his Merlin appears a raving lunatic. Just the names and possibly a round table remain, certainly not a King that switches between "protect the weak" and "might makes right" due to whichever is in his interests. He's at least provably non-historical, as we know the English didn't sack Rome.