Zeiss Ikon

Well, not today, but a couple days ago, I managed to strand three of my career's four experienced pilots in LKO. Had a contract to build a station for LKO -- must have power generation (solar panels, check), antenna (one Communotron, plus a high-gain, just for giggles -- check), accomodations for eight (two Hitchhikers, plus a Cupola for control, check), docking clamp (newly unlocked Clamp-o-tron Jr., check), and must have two pilots and two tourist aboard (Val and,recently rescued from LKO, Lufrid). Went off like clockwork, circularized at about 85 km. Solar array easily keeps the batteries charged for eclipse periods. It's small, and not pretty, but the contract closed. Okay, now I've got four kerbals stuck on a station with no engines -- I'll be expanding this one, by the way -- and two of them are tourists (their "Orbit Kerbin" clauses are completed, but I still have to recover them safely). I had recently built a rescue vehicle for the Lufrid rescue; a tiny mod (stick a Mk. 1 Command Pod on the small end of the original Mk. 1-2, so as to have three empty seats, rearrange RCS and take off the overkill deorbit tank/motors), and up Jeb goes, to bring back Val and the two tourists and leave Lufrid in command of the station. And can't get a close enough encounter to even think about docking. May have shot myself in the foot putting the station in such a low orbit (note to self -- boost station at least above 150 km once able to dock). I can see part of my mistake -- kept trying to put my rescue craft in a lower orbit to catch up to the station, vs. going higher and letting the station catch up over a course of several orbits. Finally gave up on trying to (get close enough to) dock, thinking I had just enough RCS fuel left to get Jeb down. Turns out I was wrong; RCS ran dry with a periapsis of about 70,500 m. So, now I've got one experienced pilot left: Adeny. He's done everything Jeb and Val have, in terms of learning experience -- been to the Munar surface and planted a flag, and all the stuff that leads up to it. His mission, however, is a little critical -- he has to, first, dock with Jeb's stranded pod and push him onto a reentry orbit (Jeb could probably manage with his suit jets, except I've had very bad results trying to get out and push in the past -- without a probe core, the vessel is more likely to just tumble than to actually change velocity enough to notice). Then he has to dock with the new Kerbin Station Alpha, boost it into a higher orbit, and bring back Val and the tourists. I'll add a service stage to the rescue vessel, both to give more dV on orbit and to improve maneuverability (trying to turn the entire booster core with just the pods' reaction wheels takes too long and uses too much EC), but in some ways, this is a "one try" mission. If I manage to strand Adeny the same way I did Jeb, I'll have to hire a green pilot (no pun intended) to try to rescue everyone... Longer term, I'm going to have to do something about space debris. I now pretty routinely get close enough to dropped stages in LKO to see the little box. Must have a dozen or more just with periapse below 100 km, plus another half dozen in higher orbits. Haven't had any unintentional "near miss" encounters (say, within 10 km), but it's getting annoying to select a target or set a maneuver node in LKO.

As I recall, some program or other actually flew a Gemini spacecraft that had the hole in the heat shield (originally for a hatch to allow crew to pass between the Gemini and a crew module that was to be attached in place of the "trunk" adapter seen in Gemini-Titan stacks). The hole, big enough for a human in a space suit to pass through, apparently caused no problems. That said, I'm inclined to use fuel ducts as well, in the rare case when I need to bypass a heat shield.

I suspect that the flow rate needed to keep the core from melting due to residual heat is far less than what's needed as a moderator. It does imply that you can't just "shut off" thrust, however -- minimum cooling flow will still produce considerable thrust, albeit only a small fraction of normal operation. The other big thing with these LH2 designs is: LH2 isn't even space storable. You can't fly this engine to, say, Jupiter, because most of your capture remass will boil off during your transfer. So, TWR is too low for launch, almost too low for transfer from LEO, and the engine can't be used after a long flight. And for the LPNTR design, there's really no point to trying to run it on something with longer tank life like water or ammonia -- the Isp won't even be close.

You might be right -- but my darned car payment says that isn't going to happen.

If this build were just for KSP, there'd be no question -- clock * IPC / $sys would be the only metric that matters. However, I still need to do common desktop stuff on this machine, some of which assuredly does benefit by higher thread count -- and since the 8-thread Core processors with high clock were out of my budget, this looks like it's still the best deal for the dollars I had available to spend. Not to mention I needed at least one PCI slot, else I'd have had to buy another SCSI card (for my scanner), and the "latest and greatest" motherboards that accept top-end Intel CPUs seem to be dumping PCI in favor of multiple x1 and x16 slots (some of the latter which run slower than x16 speed, despite x16 connectors). If I had thousands of dollars lying around, I could build a super-machine that would do KSP and everything else well -- 4+ GHz i7 or Ryzen with 64 GB RAM, PCIe-x1 direct SSD for the OS, $1000 video card, etc. This is not going to be that machine.

I'll be making that comparison (well, as nearly as possible) after my upgrade. Same graphics card (GTx950), same SSD, but new CPU, MB (required for the new CPU), and RAM (required for the other new hardware). I'll be happy if I can just stay out of yellow clock with a 50+ part vessel in sight of Kerbin's surface.

YouTube has a recommendation system; they show you more videos like those you've watched recently. This one came up in that category today -- it's older than the one above, but live action instead of animated, and covers differing conditions on various planets (but seems aimed mainly at crewed flight).

I'm not stuck on AMD or Intel -- if I could have afforded a 3.5 GHz or faster i5 or i7 (which would turbo to 4.2 GHz), I'd have gone that way following a previous discussion indicating an i5 at the same clock ought to outperform my Core2Quad for KSP -- though I haven't been seeing that on my laptop's i7 dual core at up to 30% higher in turbo -- but CPU + MB cost for the FX8350 was hundreds of dollars less than a 3.5 GHz dual core i5 plus motherboard, and RAM about the same per GB (don't recall if the RAM spec differed, but if so, it wasn't a lot of $$ difference). I don't see the single core performance of the FX8350 per GHz being any worse than a Core2Quad (ten-plus year old architecture -- this exact chip was available when I first upgraded to Core2Duo in 2007). And if I find it's still too slow, anything that fits an AMD3+ socket can go in its place (when I have money to spend on the computer again). I'm here to tell you, those benchmarks don't seem to apply directly to KSP. Same total RAM, less than 10% difference in CPU clock (standard speed, not counting turbo on the i7 mobile): my laptop (Core i7 mobile, 2.9 GHz with turbo to 3.5 GHz) is barely faster in KSP than my desktop (Core2Quad 2.7 GHz). Unless there's a huge(ish) difference between Ubuntu 14.04 (with HWE kernel, 4.04.* series) and Ubuntu 16.04 (4.10.* series kernel), I don't see any way to reconcile that with 70% higher single core performance from the Core i7 mobile.

This upgrade is around $535 so far -- I upgraded my power supply last winter when my computer suddenly wouldn't start (turned out to be a motherboard failure), and I installed an SSD three years ago, when the 256 GB size came down to a reasonable price.

Hmmm. Don't forget, my Core2Quad at 2.7 GHz is close to the same performance as a dual core i7 mobile the same clock speed. Unless AMD is still flatly lying about their clock speed I should still see a significant improvement (a few years ago, they labeled their chips with "equivalent speed" because they were more efficient than Intel, but they couldn't crack the 2 GHz barrier for actual clock speed -- but they've obviously long since busted that).

I'm on Linux, so DirectX is out for me (not present natively, and DX9 doesn't work correctly in Wine last time I checked; I have to run There in OGL via Wine). I thought I was running OGL by default for Linux native software, but I'm not sure how to verify that. The only other graphics intensive games I run are There, Path of Exile, and occasionally Myst Online: URU Live (all in Wine; MOUL is about 15 year old software, so not very demanding by today's standards).

Assuming that's not just wonky translation from Russian, my presumption would be that they're still talking about still air in a basement, in which the CO2 can settle out. Then the candle starts a convection loop that draws the concentrated CO2 from near the floor, and snuffs itself out. If the CO2 is uniformly mixed with air, it won't put out a candle at 10% concentration; in fact, it has to be close to 50% to reduce the ppO2 enough for the candle to suffocate. This same convection loop effect can lead to a flash fire from heavier than air combustible vapors -- acetone vapor is known to do this, as is butane. The vapor settles to the floor and spreads, then convection from a flame (candle, furnace or water heater pilot light, etc.) draws it to an ignition source, whereupon it flashes back along the vapor/air interface, causing rapid convection mixing and a near-explosive buildup of combustion.

The last couple days, I've had packages arriving on my porch. Yesterday it was a couple RAM sticks. Today, a new AMD FX8350 Black Edition -- 8 cores, 4.0 GHz, unlocked (allowing overclock capability to 5 GHz). Soon, a motherboard to accept the parts (and presumably to let me plug in my existing expansion cards, though I might have to get a PCIE-x1 PATA controller for my old 120 MB platter drive, present as a "last ditch" in case of boot issues, and CD-ROM). This is upgrading from a Core2Quad with 8 GB RAM -- should be a nice step up, 50% higher plain old clock speed, and for most other software, the doubled core count should improve things a good bit as well (I should see close to triple my credit rate on BOINC distributed computing tasks). I've got plenty of power supply, I'm already running from SSD, and I have an nVidia GTX950 with 1 GB VRAM. I might find myself finally able to install some eye candy mods like E.V.E. or Scatterer -- or at least turn up the quality in the stock game. This should also improve my experience in a couple other games -- There has always been laggy (another single-core game), and Path of Exile just barely worked when I had 4 GB RAM (haven't run it since my last MB swap let me upgrade to 8 GB).

Yep. As @Green Baron noted, as long as you have enough pressure in the combustion chambers, if fuel will burn at zero velocity and at ambient pressure, it'll burn in an engine.

"There's a pressurized vessel; I want to kill the occupants." Draws pistol -- FN Five-Seven, high velocity, small caliber jacketed bullet. Fires, punches through both sides of the pressure hull. Waits. Waits longer. Notices the (tiny) leak has stopped blowing vapor. "Dang, alarms and patches." Pulls out shotgun loaded with high velocity tungsten shot. "Let's see 'em patch this." I was talking about shooting through a car body, actually. The question was about lasers, with or without an electrical discharge along the (ionized) beam path. BTW, the electrical discharge needs a full circuit, meaning the shooter gets the same zap as whatever he's shooting. If the target is free flying, you can't zap it (no ground connection).

Thanks! I didn't even know there was such a thing, I was just wanting to pass along a cool video I found on YouTube.

I don't see lasers replacing "kinetic energy weapons" for general purpose mayhem any time soon -- as noted above, it's far easier at a human-portable scale to carry around small premeasured quantities of chemical propellant and use those to induce kinetic energy in a sturdy mass, than to try to keep enough electrical energy in a portable battery/capacitor/generator to produce a damaging laser pulse. A ruby laser that can burn a tiny pinhole in a razor blade weighs, at a minimum, around 10 kg, and the (additional 5 kg) battery is good for half a dozen pulses, max. Due to focusing requirements, it can do this only at a precisely set distance. A pistol that can punch a 10 mm hole through metal thicker than a razor blade at any range up to at least 25 m (likely more), and still kill afterward, weighs about 3 to 3.5 kg loaded with as many as 18 cartridges -- and another magazine of 18 weighs around half a kg. Also, the pistol commonly costs less than $1000 (mine was about $650, factory new), while just the ruby rod for the laser above costs more than that unless you can find one at surplus.

Just confirmed from photographs of original engines -- the rotary engines of WWI (the Sopwith Camel and Triplane had them, and so did the Fokker Dr. I triplane -- along with a few other models) were right rotating, meaning pulling up would give a strong precession turn to the left. This wasn't the reason for the starboard island on carriers, though -- if a rotary engine aircraft ever flew from a carrier, it was an experiment. Carriers effectively didn't exist in WWI; the technology of landing on a ship wasn't invented until near the end of the war, too late to deploy anything before the Armistice. Those earliest experimental carriers didn't have real islands anyway; they were just cut-down and decked-over cargo ships. The position of carrier islands was established in the run-up to WWII, when much heavier, more powerful aircraft were launching from the deck. For those craft, P-factor (an artifact of angle of attack interacting with the propeller's rotation) was the big factor in takeoff turn, rather than gyroscopic effects, and it didn't matter much; from a carrier steaming to windward, even a fully loaded attack craft could get into the air using only the forward half of the deck, without having to pass the island. Accidents on landing were just as likely to threaten a starboard island as a port one. The island was put on the starboard side because ships dock on the port side (that's why it's called port) and loading was greatly simplified if the island wasn't in the way -- you could just lower the elevators and move aircraft, ordnance, and so forth directly from the pier into the hangar decks.

You picked a rather poor "bad example" -- the P-61 was very capable with an engine out, in some ways better than a P-38 (though otherwise, it was far inferior in performance -- but as a night fighter, it was built to different goals): "Full control could be maintained on one engine—even when fully loaded. It could be slow-rolled into a dead engine, a maneuver that was devastating on the Lockheed P-38 Lightning." Twin engine aircraft (other than push-pull designs like the Cessna 337 Skymaster, aka "Mixmaster") generally have lots of rudder trim authority, specifically to allow operating a single engine at maximum power without an uncontrollable yaw response. Engine out procedures for twins generally run similar to this: identify dead engine (it's the one opposite the floored rudder pedal), feather dead engine (turning propeller blades edge on to the air, which reduces drag), trim for straight-ahead flight, then fly normally (likely at higher than cruise throttle on the good engine) while declaring an emergency and landing at earliest opportunity. Another aircraft with far larger separation between propellers (though the engines were buried inside the wing) was the Flying Flapjack -- a basic precaution avoided "engine out" problems: the propellers were geared together with an overrun clutch on each engine, so either engine could drive both propellers (the same thing is done with modern twin rotor helicopters, even with the V-22 Osprey, for similar reasons).

As far as I know, two engines are always better than one from the standpoint of safety. Engine-out performance wasn't always a design criterion (for instance, a Ford Trimotor could barely climb on two, especially if the one out wasn't the center one). Then again, some twins (notably the P-38) had very good one-engine performance. I forget who it was, but there was an air show pilot who used to fly a full aerobatic pattern in a P-38, then shut down one engine and feather it's propeller and repeat the entire pattern on one engine (the fellow who did the same in a much newer business turboprop died a few years ago when a wing came off when pulling out of a loop). FWIW, the "engine explodes, now you don't have a wing" is extremely rare, absent things like cannon fire or air-to-air missiles. A bigger problem has been "engine mount fails, now you have 1200 lb more weight on one engine mount than the other" (few aircraft have enough roll trim authority to survive that), and even that is vanishingly rare. In general, a single engine failure amounts to "engine has a lubrication, electrical, or fuel delivery problem, can no longer operate." In this sort of failure, having another engine on the other wing changes "I'm going to make a dead stick landing, right now!" into "I need to divert to the nearest airport that can handle my aircraft." Both are emergencies, technically, but the former is far more likely to result in loss of airframe, crew, and passengers or payload. It's this difference between "going down, NOW" and "I need to land soon" that has made twin (and more) engine aircraft the darlings of commercial air travel. Having a backup engine (in an aircraft designed to keep flying on one, if needed) has been the biggest single factor in bringing commercial air travel to the forefront of travel safety. The DC-2 showed how it should be done (it could, if not overloaded or at extreme density altitude, take off and fly a normal leg on either engine, as was demonstrated when it was introduced); the DC-3 (longer, wider span, a few more horsepower on each wing) showed how to do it at a profit on a day to day basis. BTW, I don't recall if anyone mentioned the Blohm und Voss BV-141 -- a German light bomber and recon aircraft from late WWII. It had a single engine and tail boom (on the left), and next to it a fuselage with forward bombardier position, pilot/copilot seats, and rear tail gunner. A bit like a Boomerang without the pilot-side engine. Aside from turning a little differently to the right, as compared to leftward, it was said to be very conventional in its performance. The original design goal was to give twin engine bomber forward visibility and tail defenses, with single engine cost. I've heard that it was part of the original proposal to make them in right-engine form as well, so a formation of them could be equally defended on both sides, but the war went from offensive to defensive about then...

I can't say for certain that this is applicable to KSP (a lot of real world solutions aren't), but here goes: For model airplanes, a taildragger (i.e. conventional gear, that is, two wheels slightly ahead of COM and one under the tail, often physically linked to or even mounted on the rudder) has a strong tendency to ground loop -- this is exactly what you're describing, where the aircraft swerves to one side during the ground run, either on takeoff, or after landing. The solution to this is to build the main gear with a small amount (two or three degrees is enough) of toe-in. The way this works is that when the aircraft inevitably starts to get a little out of alignment from its velocity, the wheel that's being pushed forward (by the yaw rotation) and downward (by the torque reaction to the side force from the gear) will generate more drag than the one that's having weight taken off. This is because, with the toe in angle, it's scrubbing on the surface more than the other. This drag acts as a brake and tends to restore the aircraft into a nose-forward attitude, automatically. The reason I'm not sure if this will work in KSP is because I don't know how well KSP models the friction between a wheel and a surface. If the friction isn't related to the "normal force" (as we used to call it in Statics & Dynamics courses), then toeing in the main gear won't do anything to help, but if more weight on a wheel makes it grip better (yet still allows it to slip a bit), this is the easiest solution to keep a "conventional gear" aircraft straight until you can pull the nose up and lift off. As a bonus, it'll also keep the thing straight after a reasonably non-crash-like landing.

The book(s) was(were) The Integral Trees (so named because the mechanics of an orbiting gas torus meant the inner and outer ends of a tree would bend in opposite directions from the winds caused by orbital velocity differences), and The Smoke Ring. The people didn't evolve there; they were humans, survivors of a mutiny of an exploration ramship (Niven never did give up on Bussard ramjets, even after it was proved they couldn't get anywhere near lightspeed). The Smoke Ring, as they called the gas torus, orbited a neutron star or white dwarf known as "Voy", drawn off by extreme tides from a giant planet known as "Gold." Yep, read the books a couple times...

The main reason red is used for lighting in situations like submarine and ship command centers (during emergencies at night), as well as for necessary lighting at astronomy gatherings and so forth, is that deep red has the least effect on the darkness adaptation of the human eye. Even a fairly bright red light (one that, for instance, allows reading fine print) won't destroy the eye's ability to see in darkness when the red light is turned off or blocked. All mammalian eyes, dichromat or not, have reduced sensitivity in red compared to other colors. Dichromats may have more reduction in that range, I'm not really certain. Interestingly, some darkrooms (particularly when handling color or panchromatic sensitized materials) use the dimmest possible light -- in green. This is because the human eye is most sensitive in the yellow-green wavelengths, so the light can be several times dimmer than a red light and still allow, for instance, seeing the forming image in a negative partway through development -- with a minimum of light to add fog to the final product. The light can be made so dim that it takes many seconds of exposure to have any effect on the film, and a fully adapted worker can still see well enough to adjust a coating machine, inspect a partially developed image, make sure panchromatic printing paper is emulsion side up, etc. Now, most of these operations are done with IR goggles and illuminators (at least for materials that aren't IR sensitive), but the dim, dim green light was used long before IR and light amplification devices existed.

As I understand it, all mammals see red, they just can't distinguish it from green (unless they're rodents or primates), like a human with dichromatism (aka color blindness). I'm not sure what having only yellow-blue cones in your retina would do to change the wavelength limit of your vision, though -- what I recall is that all kinds of cone cells (red-green and yellow-blue, plus the third "alternate red-green" that about one person in 100,000 has) have similar wavelength limits, but they have different sensitivity peaks (the red-green cones peak around 600 nm, as I recall, while the blue-yellow peak close to 500 nm -- and the summation of their curves places the actual sensitivity peak of human vision very close to 540 nm, a little to the green side of the yellow sodium emission line).

Infrared emission at 310K contains so little of the wavelengths approaching 700 nm that it's below the sensitivity threshold of the eye's receptors -- just like a body at 500K (temperature of a slow oven, near enough) emits so little visible light we consider it "invisible" (even at that temperature, the IR-pass goggles and long adaptation probably wouldn't show you anything). Remember that the human eye's sensitivity to IR is both limited to the shortest end of that spectrum (for most individuals, shorter than 750 nm), near the visible deep red, and of very low sensitivity (it takes rather a lot of radiation below 700 nm to register with even a fully dark-adapted eye, hence why the goggles work best outdoors on a sunny day). Even the IR sensitivity of common silicon video sensors (with the IR block filter usually used with those devices) doesn't extend far enough to pick up thermal IR from a human body; you need specially designed sensors to go below about 1000 nm.