wumpus

More likely he believes that he can eventually scale bigger than anyone else and wants to make sure he can build to scale. It worked for Amazon, it worked for AWS, but it isn't clear how it will work for BO. I can't see New Glenn launching before Starship, at which point catching up becomes profoundly difficult (you can try to out-scale Rocket Labs, but I don't see the point).

Why wouldn't it be a SSTO? Simply use the electricity to heat hydrogen, then use as a NTR with an Isp>1000s (first pass the hydrogen over the battery to cool the battery, then pass it through heating coils to further heat the hydrogen). Other than the unbearably large fuel tank, it should have no other SSTO issues. The big question is how in the world does adding charge create antimater, and how a reversed operation would create electricity (I thought I posted a reply yesterday which assumed that the battery would be nuclear. A chemical battery storing electricity better than chemical fuels seems unlikely. Of course once you are in Earth's orbit, you can theoretically use the Earth's [or any other planet with a magnetic field, not sure their are any good targets] magnetic field for a truly reactionless drive. Note that such a drive would likely be slower (no matter the tech) than current ion drives, so perhaps your fictional people won't even use it for cargo, but I'm pretty sure a proof of concept was done on a [tiny?] sat. And you are discovering part of the reason that Rocket Labs only uses electricity to drive the pumps in the Rutherford engine (and not even the planned larger Archimedes engine).

When the witness testified to the existence of soil before the existence of life, he easily discredited himself as an "expert". The attorney should have used seawater.

"second stage, which will have an annular aerospike" Any idea why? Presumably the first stage (assuming they build one, it might not make sense to compete in that area) would also be an aerospike, but traditionally it makes no sense in vacuum.

They certainly would have trouble building in Miami. Anything not highly developed near Miami is protected Everglades, and I'm fairly sure they can't build in Key West (and launching over the Keys is probably a no go as well). I'm guessing they also don't want to pay Hawaiian salaries (although if you advertise in Chicago during the winter, you might get bites from people who are used to expensive living).

I'm rather curious if we are dealing with the Gell-Mann Amnesia effect. In the 1980s it was not trivial to do fact checking the same way you can do it in the age of google (although this doesn't seem to help the Facebook crowd). I distinctly remember reading quite a few things in the 1980s and being shocked just how wrong they got it. It seems rather suspicious that an institution suddenly becomes so very wrong at almost the same time it becomes possible to check how wrong they are.

Other things wildly different in KSP is that you can adjust the thrust profile of solids ahead of time: this is typically done by altering the cross-sectional geometry of the solid. And of course, throttling liquid rockets is vastly harder than shown in KSP. Still, as far as I know, only NASA uses solids for large amounts of thrust. This is largely because ICBMs typically use solids or hypergolics. Most ICBM designs tend towards hypergolics, but such designs became unpopular in the US after a Titan II blew up a good chunk of Arkansas. This gives Thiokol a larger say in NASA designs than might be otherwise be appropriate. On the other hand, the ability of SRBs to produce *thrust* relatively cheaply shouldn't be underestimated. The Shuttle/SLS boosters are the most powerful rocket engines ever launched, exceeded only by the AJ-260 which produced 2000 tons of thrust. Adding a few boosters with only a minute of burn time can wildly change the amount of cargo you can deliver to orbit.

I didn't know they were more specific about the precooler (it is said to be the key to the SABRE). I wonder if some air-breathing spaceship might have simple ramjets for machs 1-4ish, possibly recoverable boosters. Or maybe stick the whole thing on some sort of catapult rail. Has there ever been any real work on a Skylon (outside the SABRE)? It always seemed like "an example use of SABRE", and not really their line of business. Presumably they'd work on that once SABRE was ready to move into production, but certainly expect anything to change (and I'm sure they are hardly certain of SSTO, that just looks really impressive when a SABRE can roughly make it happen).

Virgin Orbit (and Orbital Pegasus) have the two key advantages you'd want on a SSTO: low atmospheric pressure at launch (so less range to adjust output nozzles) and better scaling. The scaling issue would also bite them, as any SSTO requires so much more mass than a TSTO. The elephant in the room is that for Earth's delta-v requirements, finding any means of recovering an entire vehicle from orbit is next to impossible. Just getting there requires high Isp and massive rockets. A SABRE might work, as it presumably only has to add the air engine and fuel (not oxidizer) from the airbreathing regime. Note that it is entirely possible such a craft might burn kerosene for 0-mach 4 or something, just to use a vastly smaller fuel tank (than a huge, if low mass, hydrogen tank). I'd also like to remind everyone of the X-43 program. Hit mach 6.4 during a test flight, not just a powerpoint presentation. Managed to sustain mach 9.4 (although just barely, and the error bars definitely included purely negative acceleration). I think the Air Force has it now, and is either canceled and/or classified.

I was really hoping for a picture of rhino cavalry (why not arm the mount?) and only came up with the moose. The boar in the background looks better, but probably bigger than you can breed pigs (assuming that they aren't bred to be roughly modern size because anything bigger would be unsafe or eat too much food). I also suspect training boars would be even worse than trying to training moose. A heavy warhorse is far larger than any human enemy: the main reason they weren't specifically armed is that you'd expect a horse to fight with a kick, and said kick would use the bottom of the hoof (nowhere to put a weapon that wouldn't interfere with movement). Maybe breed a huge goat (possibly with boy riders) and put a spike on the head? A lot easier to train to use the weapon.

The Great Smog of London was the shock that made the English try to clean up London air. https://en.wikipedia.org/wiki/Great_Smog_of_London (no idea of the accuracy of this) I'm not sure if there was any specific effort to clean up Pittsburgh during the days of "Hell with the lid off" until the great dying of the US steel sector in the 1970s (there was some effort during the end of it, thanks to the Clean Air Act. The coincidence between real competition and the Clean Air Act and the disporia of people from the Pittsburgh (and surrounding "steel towns") likely seeded the country with plenty of people against any attempt to curtail air pollution. There's a good chance many of them wound up in southern California (a place that seems to be high in places Americans think of when considering just picking up and moving *somewhere else*). I was in California in the mid 1990s. I took off from San Francisco when the thick fog (not at the airport, but right at the end of the runway) lifted. Landed in LA in another batch of fog. Later that week, I realized that the fog was gone and that this was merely typical pollution levels for November. I'll never forget the orange air from the "red at night" effect. You could look through the air and it was orange. Was also there around 1984, but don't remember anything specific about how bad the smog was (it was probably peaking then).

I've never heard that line, and since I'm about 50 I certainly remember the [first?] era of nuclear deterrence. Sure, you could claim that modern cities are safer from fire than 1940s Japanese cities, but few nuclear delivery systems bother with such primitive weapons as pure fission devices (possibly not true as more nations enter the "nuclear club"). It hardly seems to matter if your house wouldn't burn from a Hiroshima-class nuke if a 20 megaton warhead puts you in ground zero. And just because your house didn't burn down, you now have a bigger problem of where your next week's meals are coming from: every car's electrical system was just fried thanks to EMI. I suspect the same happened to every delivery truck. If you can't obtain food more or less directly from a farm (did the fish survive? Can you live that way?) your house won't matter at all. Burnt down or not, any house even lightly hit by a nuke is probably in an area about to suffer a serious famine (survivable if the hit was local, nation/continental wide I hope you know your 18th century tech). Presumably just about anything burns less than traditional Japanese buildings (especially houses). But as mentioned, once you start a firestorm certainly modern (US anyway) towns burn as well as forests. Traditionally, fire was feared and treated as a disaster on the level of earthquakes. I'd assume they've but more effort into changing that, but really don't know. WWII incendiary attacks were horrifyingly effective.

I'm not sure the lance is needed. The link claims that they were indeed used, at least until Ivan the Terrible put a stop to in in Siberia. The early USSR was trying it again, but stopped when the Winter War needed real units. All I know is that backpackers in the US are told in no uncertain terms to never try to ride a moose (it is possible to get on when the moose is in a river, presumably swimming. Survival becomes impossible if you are still on when the moose regains its footing).

It wasn't a rocket and didn't fly. Although I think retrofitting it with the rest of the gear to make it a shuttle was considered a number of times, it was always cheaper to build from something else. I'd be shocked silly if they know what Little Joe was (https://en.wikipedia.org/wiki/Little_Joe_(rocket)), a similar helpful prototype launcher.

It appears to be designed for a "joust of peace" (blunt weapons, but don't be surprised if you still have multiple deaths). I don't know if anybody designed lances with a "tined fork" (using the outer tines to guide the middle to the center), but it looks like such would work on the neck. And break just as easily anywhere else.

The AF is also weird in that when the officers go off to battle, the enlisted guys wave good-bye... - offer does not apply to the guys stuck in land-based "logistics" and airbase protection.

Since you'd have to operate in vacuum, it would presumably work fine without the extra air (my understanding is that the air isn't an oxidizer, just adds to expansion). You'd need to close the intakes, but that hardly sounds like the biggest design issue (or they'd be in use already, if only in sub-launched craft). The whole idea is to scale up the Isp a little bit, and expect the fuel use to scale (more or less linearly) with the Isp (for first stages with reasonably heavy stages above them). I'll have to get realism overhaul up and running (now that KSP development is over) and figure out what a 3-stage starship would be like. First stage would be air-augmented RTLS, second stage would be starship-like, but only as fast as it can go without heat tiles (ideally landing in Florida after taking off in Boca Chica), and finally Starship (now starting with a higher delta-v).

I was shocked by how little delta-v superheavy booster created, so have to wonder if an air-augmented booster would make sense (leave original raptor in Starship). Not sure how effective air-augmented methalox is, but unlikely to hurt. Cutting fuel costs seems a long way out, but the was spacex moves, they might be there by the time the engine design is completed.

Fun fact: the runway at KSP's KSC is flat, and doesn't follow the curvature of Kerbin. Presumably you can tell this by noting the difference in the size of the banks needed to "raise" the runway between the ends and the middle. But Kerbin is much smaller than Earth, and the runway is designed for spacecraft (so presumably more on the scale of Shuttle landing runways, although expect Kerbal aircraft to cheat a lot). On Earth, I'd be curious if the difference of such a table (let's say round, with a 2.4m radius) matching the curvature vs. non-matched would be more or less than difference between the Hubble mirror and the specs for the mirror (sans spherical aberration). And yes, you'd need to polish the table like such a mirror to get the measurement to be meaningful.

The X-15 had RCS, but I'm sure it used aero surfaces while in the atmosphere (it had enormous and draggy aero surfaces for stability). I don't think it could gimbal, I strongly suspect that aero surfaces worked far better than gimbaling could.

According to Scott Manley, a similar means was used to find a way to manufacture the AJ-260 (a monsterous SRB 3 or 4 times as powerful as the F-1. Test fired, but never used in a rocket). They realized that it had similar requirements as a submarine, and contracted out a submarine builder to make it.

Actually, he points out that the "acceleration" (although it is a change of the direction of the velocity, not the magnitude) is almost the same. Not only that, but the g-forces are in "the wrong direction" (although presumably trivial to design around).

Both Spacex and Orbital seem pretty strong in their positions. I can understand either economics or one of these startups mutually killing Rocket Labs in a price war, but both Spacex and Orbital seem to have a working business model (and it can't hurt to have Northrup Grumman bringing more Military Industrial Complex lobbyists). Technically Blue Origin has a working model of "Jeff Bezos throws a few billion to it every few years", but that depends on his whims. The rest are in a precarious position, built more on hope than any financial foundation. Worse, Bigelow appears dead even when their market is finally ready, and didn't even have competition in their niche.

I only complain about hypergolics in booster (first and such) stages. There are plenty of reasons to use them for later stages, satellite position control, and RCS devices (they are nearly ideal for RCS, especially uncrewed vehicles not coming back to Earth). Remember, the poison is in the dose: and the amount of propellant decreases exponentially the further up the stages stack you go.

Basically because of the extreme limitations already covered in this thread. You'll still need a [presumably solid, to survive multip-thousand-g-forces] a second or third stage, which means you gun has to be big enough to be largely launching a [second stage] booster instead of launching a spacecraft. Compare to air launch, which trades large mass (and volume, and often the ability to "top up" lox or lh2) requirements to allow a much larger bell and less air resistance while launching. Two companies have successfully done air launch (Orbital and Virgin Orbital. Did a MiG ever launch something into orbit or simply demonstrated anti-satellite capability?), but nobody has gotten close to cannon launch. I still like the idea of launching a SCRAMJET with a railgun. Not that the tech is remotely ready, but NASA *did* demonstrate a working SCRAMJET already, and the rail accelerators are even used to launch roller-coasters