wumpus

Way back in the early 1990s I worked for a tiny startup (that didn't startup) that was building a drone with a tilt rotor. Note that as it was the 1990s, "drone" meant nothing more than a glorified RC aircraft. But this one was a joint project with Scaled Composites and was designed by Burt Rutan. The company I worked for was called Freewing, and so named because they were building planes that allowed the wings to rotate freely to a constant angle to the wind. Mr. Rutan figured out that this would make tilt rotors far easier as the wings would naturally maintain the right angle for lift, and simply placing a rotor between tail and fuselage/engine would force the fuselage (and thus propeller) to whatever angle you wanted. Alas, it was built a little too early (between the two wars in Iraq) and had French backing (a real disaster for the politics at the time). http://acversailles.free.fr/documentation/08~Documentation_Generale_M_Suire/Conception/Formules_speciales/Divers/Freewing-Aircraft.pdf A collection of stuff printed about them. I'd take the job titles at the start with a grain of salt: the first two I remember. But the rest of the employees consisted of an American mechanic/assembler a French electrical engineer (a bit to green to have a straight out of school [me] EE under him), and a Chinese aero engineer (unforgettably named "Yu Hu"). The company could likely replace all but the mechanic/fabricator reasonably easily (maybe he's the "project engineer". I can't see him showing up at DoD meetings as a "project manager").

Presumably your best bet is to keep hopping towards the center of the Milky Way. You'll be able to get to many more stars as they get closer together. No idea how old they are and how that would effect if it had habitable planets or not. And don't forget that every jump effectively changes the past.

Note that this largely applies to resusable vehicles. Most early rockets (including Sputnik) were 1.5. 2.5 makes a lot more sense, but still requires an additional engine, controls, etc and lighting the engine in vacuum.

The Earth's moon is rather large compared to the size of Earth. Adding a second Luna sized moon to the Earth would probably require something like the Jovian system or more likely one of the sitting in a Lagrange point. Beyond that, it looks like everything was covered in Tomf's post.

Highly charged project or depression-treating propaganda? Who knows.

From what I've heard, the issue wasn't even decided until the "International Geophysical Year (1957)" when the US announced it would put something it orbit (and was 2 months late) and the USSR *did* put something in orbit without serious complaints of border violations. Before the announcement, NACA/DoD (or whatever existed before NASA, and for all I know it was still Department of War) had no idea what the Soviet reaction to a satellite overflying the USSR would be.

While it takes more delta-V, you only need to accelerate a tiny fraction of the mass to your cycler. So it becomes wildly cheaper for every trip after the first (including the trip home from Mars). The best argument for not doing it during an early trip to Mars is the maintenance requirements of the ISS are so extreme that there is little hope for the thing to be operable after another trip to Earth orbit and back (granted, it wouldn't have much protection orbiting Mars either). As far as "expendable", the only important point is that it won't ever land (even on Mars). So refuel it if you want (although assembly in LEO seems to be the only current option). Once assembled, I'd recommend nuclear or Hall thrusters to get to L2/MTO and Starship (or similar) to take your passengers to the habitat. The only big difference between a cycler and an expendable transfer unit (i.e. at best one round trip) would be that you'd rendezvous at L2 and burn the ~1000m/s to MTI while the passengers are on board.

I'd assume that for long-haul spacecraft, the volume targets should be based on submarines. And to "help Musk", I'd suggest building habitat modules similar to ISS, firing them up on a Super Heavy Booster (plus some expendable 2nd stage) and connecting them up in orbit (right now the only technical option is alongside the ISS. That would be politically tricky. Note that such a habitat can be reused, see the Aldrin cycler. Of course this means you also have to pay all the delta-v to get to it, so presumably you can take your "100 passengers" and with enough refuelling pay the ~13,000 m/s delta-v needed to go from sea level to Mars intercept and dock with the cycler/habitat (hope it is big enough for 100 passengers). How to return the Starship is up to you, and docking it and using it as a "Mars shuttle" makes the most sense (and don't be surprised if you need a lot of Starships to shuttle to the cycler to meet the window requirements).

Note that immediately afterwards it lists how to make a star profile with a neutral thrust by modifying the grain profiles or added inhibitors. It also shows that a rod and cylinder naturally has a neutral profile, but you have to support the internal cylinder. It appears that for minimum thrust, you need a rod and cylinder profile plus the lowest thrust grain profile you can find, although it might be better to use that star profile and some barely higher grain profiles + inhibitors. No idea what the "inhibitors" do to your Isp. More likely the youtuber who followed a youtuber who followed the A. Cookbook. And since most of the youtubers appear to have lived, it must be one of the safer recipes in that book. I think the Tech Ingredients channel does a similar thing, but skips the whole "sugar" process in favor of straight aluminum nitrate or similar "real" chemicals. He appears to have the right background for such things and includes appropriate warnings (although likely geared for people who may have copied earlier designs, not necessarily for those the youtube algorithm thought they were looking for A. recipes).

Interesting. I've wondered how to make a "long burn" SRB for a final stage. Since the "dry mass" of a SRB is entirely based on the pressure (and thus the thrust), having a long, low thrust burn would allow a better wet/dry mass ratio and thus a higher delta-v. Of course, this would have limits as any "bursty" thrust would defeat the purpose.

Pegasus (1990-not much longer) has 3 fins plus a wing. Virgin Orbital's rocket (taking a similar role as Pegasus) has 4. Pegasus uses solid rockets (3 stages), so absolutely needs fins for at least initial control. Virgin Orbital has at least one kerolox engine, but presumably a dropped rocket benefits more by having fins (no idea if they are used for control). As far as KSP is concerned, for less expensive rockets I like to use two control fins aligned North/South with two (or more*) fixed fins aligned East/West. Since your primary control needs involve modifying your inclination in that particular direction, it can be enough (you can eventually modify other directions by rolling and then altering the direction as needed, but expect a certain delay). I don't recommend this for any situation that doesn't include a "revert to launch" option. Also, since KSP "smallest fins" are dirt cheap, adding more of them than a larger fin may make sense in game while making no real sense in the real word. I think for post V-2 rockets, he included the fins as a personal signature on the rocket. I think he called it his trademark or similar. I also suspect that between the simplicity and effectiveness on his earlier rockets, he wasn't about to give them up when moving to more complex rockets (when was the last time a fin failed on a rocket?).

But don't bring personal shields to a laser gun fight. Or don't bring a laser gun to a knife fight.

This is orbital mechanics in a nutshell. The only thing to remember is that "the faster you have to go" is angular speed, not linear speed. And once you enter the atmosphere you have a lot more problems than just missing the ground.

It needs an ion drive, for both getting there and capture. And it isn't like it will need the full power of the radios and sensors until then, and the RTG will be spitting out the same power no matter what. Shelby isn't running in 2022. He's the cornerstone in its rock-solid political backing. And from an economic perspective, a reusable SLS wouldn't be any more sustainable. Besides, the serious cost-plus gravy train will be over by 2022 and the Senate will be moving on to Vulcan as its favorite son.

An expendable TSTO delivers a large payload to orbit. A SSTO can deliver the same mass to orbit, but nearly all of that is engine and fuel tanks. Sorry, that's how the math works and why TSTO is used. The upper stage of a TSTO will be optimized for vacuum and will always be more efficient than an altitude compensated engine of the same family, and the fuel tanks will be more efficient (as they are smaller), so they will always get more delta-v for the same fuel. So a SSTO will simply never deliver as much total mass to orbit than the TSTO. So instead of 3%, you may get 2.5%, where 90% of that is your SSTO. So instead of 2% being a satellite, you have a .2% microsat. Congratulations, and you still aren't bring the SSTO home. 2016 called. Spacex routinely lands boosters on barges. It would be even easier to build a landing pad downrange of Baikonur. Vostochny presumably has less room, but likely would still make sense. You still have all the fun of building a heat shield the size of a full rocket (and a much bigger rocket if you want any payload at all). The 1970s solution was to hand-apply individual tiles after every mission. It was almost as expensive as rebuilding the SSMEs, and that was only for the orbiter (the surface area of the fuel tank would have been worse). The X-37 budget is conveniently classified, and Starship requires some fancy active cooling pushing LOX(? some coolant) out the heatshield. It is a non-trivial thing to do. If you can handwave the recovery of a full-scale SSTO from orbit as such a trivial matter, why have the only recovered boosters been the Shuttle SRBs and Falcon 9, and that only 5 years after the initial launch? The shuttle proved how expensive it was to recover even 27% of the total dry mass from orbit. And don't forget the only reason the shuttle managed to deliver the orbiter plus a small (23 tons less than 1/3rd the orbiter's mass) into LEO was that they ditched 380 tons of booster dry mass.

For "real life": The two requirements for loans are that you should be able to pay the loan off, and that if you can't the lender can repossess said vehicle to minimize cost (and minimize the chance of default on said loan). For "games" Real life return on investment isn't fun. So games have massively overpowered return on investment. So loans break the game. Conversely, if you have real life returns and "time acceleration" (like KSP), you can again break loans and have fun.

Quick math note: The original calculations assumed that the shuttle engines would get full Isp all the way to orbit. Fixing that leads to a delta-v of ~8500m/s. Of course, since it launches with a thurst/weight ratio of ~1.9, you should be able to build that fuel tank to 125% of the original size. This gives you a thrust to weight ratio of 1.5, and a payload to LEO of 10 tons. Unfortunately, it also means that you can't use the same rocket as a TSTGeosync, which makes it far less useful. And of course if you can recover a SSTO, you can recover a TSTO booster vastly easier. And the mass budget in the booster recovery can be hidden in the mass of the second stage. The final mass budget for recovering the final stage will then be at least 1/10th of what it would mass to recover a SSTO, which is why Starship is at least in the prototype stage and nobody is building a SSTO. I would even recommend a three-stage design for a Starship follow on. The idea would be to add air-augmented boosters that would return to launch site. Then the main superheavy booster would use "starship tricks" (skydiver landing, stainless steel hull) to be recoverable from the highest delta-v it could manage. The pros: A significant amount of mass would return to launch site on its own. Presumably the savings in moving the now lighter super heavy booster back home would be less than the cost of mating the extra boosters (I'm sure this isn't true now, but spacex has a lot of experience in mating final stages to used boosters). Significant fuel savings. Moreso if the initial booster is vertically staged, but I've always thought of these as "strap on boosters". Not sure which is cheaper to mate. Granted, I don't know how much Isp gain you get with air augmented methane. Note that while this is silly thing now (spacex saves 10 times the money fishing fairings out of the ocean than it costs to fuel a Falcon 9), if you start planning now by the time you deploy such a rocket you can expect that fuel will be a more significant cost of a rocket. Cons: Extra stages aren't that cheap, and integrating them is a challenge. I'd like to think that Superheavy booster is already pretty close to as much delta-v as it can get without the active cooling tricks. But it seems like it cuts out far shorter than you'd expect a rocket with identical engines in each stage (about halfway up in terms of delta-v is where I'd start my calculations. Possibly closer to 2/3rds with a third stage). I was going to say no air-augmented rocket had been made, but it appears that a prototype for Gnom was not only designed, but launched (and worked). I'm also not sure that metholox would be that improved by air augmentation.

Feasible since the 1970s? Not with recovery. I'm really curious how you are going to recover a Delta III with only 800kg of parts/fuel slotted for reuse. And remember to design the computer controls with 1970s space-rated parts. Here's what they used: https://www.history.nasa.gov/computers/Ch4-3.html Sure, you could probably get something a little more DSP friendly than the IBM360 architecture, but don't expect to land retropropulsively. As far as parachutes go, each Shuttle SRB had a dry mass of 91 tons and parachutes weighing 3510kg. Scaling the parachutes down for the mass of the Delta III, so the parachute budget is slightly high. Unfortunately, those parachutes are designed for Shuttle SRBs which are little more than thick steel tubes. What happens when a SSME engine smacks into the water at 23 m/s (53mph. This is lower than I remember and I'm doubting the infallible wikipedia)? Rebuilding the SSME between flights was more expensive than building new kerolox engines for every flight. And that was a gentle landing on a runway, something you aren't getting for 800kg. Good luck finding anything you can rebuild after plunging into saltwater at 23 m/s (or a lot more if memory serves). Remember Earth isn't Kerbol. SSTO doesn't make sense with any known chemical with 3-digit Isp.

Then why ask about how science works if you are going to ignore it? And you also have to make sure that your super-magic-pixie dust has to make large explosions, while antimatter will scale to whatever size antimatter you have and can safely contain.

Antimatter and pusher plates make zero sense. And the real issue with the Orion isn't how much radiation comes off the launch going up (although you'd want to be a healthy distance away), it is what happens when the magnetosphere collects all the ionized heavy atoms and lets them fall to Earth. Hint: launch from Antarctica and you can avoid this issue.

For probes, Voyagers need more love (but don't merge with one). We simply had no information of the outer planets until they started passing them, one by one. A few years after launch, Jupiter went from being a fuzzy spec to being a meteorologically active planet, complete with a ring and 50 more moons than previously thought. About a year later, Saturn got a similar treatment. And then Uranus and Neptune. Only New Horizons did anything similar, taking a former planet from 4 blury pixels from a Hubble camera to detailed maps of (one side of) the surface.

Mostly true, but I've used software I rather liked that typically wanted all length measurements in either imperial (mills) or metric (mm), and thought that it made more sense to do the occasional calculation myself when the devices were speced the "wrong" way than to flip the thing back and forth between metric and imperial (even though it was probably storing everything as a double and it wouldn't have been an issue). Also the story took place in a startup incubator on a college campus, so including school calculations without the crutches made sense. Finally found it: long, long ago when i was studying high school chemistry, the teacher was teaching the "factor label method". This was a huge help to me in that it not only solved basic high school chemistry problems, it also was used to solve any conversion issues in any physical science problem in any other class (or professionally, although you'd probably use some sort of similar software). This video even includes his "bar notation", something I haven't seen during my occasional googles of "factor label method" https://www.youtube.com/watch?v=K33txxFsnrg

I'm guessing that you are dealing with "fractal accuracy". You get the main points accurate, but now have a lot of minor points that will only be accurate if great care is taken to get them right. If great care is taken, then there are even more more minor points to get right. And so on and so on. Not only that, but after getting the main points right, there's no particular reason for the secondary points to be part of the same narrow discipline as the first. Meaning that very few people will have the background knowledge to get them right, even if "great care is taken", you'd have to find consultants (and even then you have to have a gut feel for the right fields that could have problems with your plot points). There's a reason the golden age of science fiction is 10-14. By the time you get to college, expect to know more about at least one field [which field may depend as much on the author as your education] than any author you might read (a favorite author of mine had the misfortune to write a book heavy in orbital mechanics right after the release of KSP. I'm sure I'm not the only fan of both...). You *will* see errors, if not in the physics, at least in other basic sciences. And that's sci-fi genre fiction, which traditionally cares about getting the science right (at least up until the 1970s, but there are a few carrying the old school traditions). Movies never really cared, and after Star Wars' runaway success is likely to be even hostile to accuracy. There was a "script explanation" going around mentioning that all the Star Trek science consultants do is put the right words in the technobabble. The script says "shouldn't we just tech the tech?" "no, you have to tech the tech first, then you can do that". "ok, lets do it. And when the script comes back, the "tech the tech" has been replaced with reasonably appropriate science/technological words.

On the whole idea of "base 10 vs base 12 or base 60" (the base 60 system that time and circles still use dates back to Babylon)... Sometime around 2000 the New York Stock Exchange went from stocks having their traditional fractions to going decimal. I suspect IBM was behind it, because they're the only computer company that really includes a "base 10 mode" (Intel has one, but it is so limited it appears to be included as "checkbox engineering"). The fractions NYSE used were all naturally base-2, and were as easy for a computer to do the calculations as any old timer could. Simply define the "decimal point" three bits to the right and your 16 bit word (expect to special case Berkshire Hathaway, or just use 64 bits for everything) now deals with integer values of 1-8192 and fractions 1/8 to 7/8. Lets just say anyone who thought decimalization made things easier for computers doesn't get the "10 types of people" joke. Probably including far too many modern programmers. My first job was at a startup working under a French engineer who would often argue with the American fabricator/technician about "sillymeters" (I was also told that "soccer" was pronounced "foitball" and football was pronounced "football" (emphasis more on the long oo than the t)). The Frenchman once mentioned that he didn't have much of a problem working with Imperial units as he would convert everything to metric and convert the final answer back. The tech admitted that he did it that way, and so did everybody else.

In "Carrying the Fire", Micheal Collins insisted that "ft/sec" was the only proper way to measure spacecraft speed, although that was typically compared to mph. Luckily for electrical engineers, there are no imperial measurements for electricity: no 12 1/2 Edisons to the Franklin. Although some PCB manufacturing places expect your PCB to be designed using "mills" (1/1000th of an inch, not mm). For people who grew up on imperial, I highly recommend exersizing in "imperial": measure weights lifted in pounds, running in miles (and speed in miles/min). It seems better in convincing your body to get stronger and makes any improvement more naturally undestandable. Otherwise there is no good reason to use them.