Zeiss Ikon

Yep. If it really, really bugs you, don't use the large turbofan engines...

If the test isn't on the grounds of an airport, and the engine never leaves the ground (as with the static test in the video) FAA won't have a word to say about it. As long as you don't illegally store "explosives," produce something that's illegal to possess, or create a hazard to life or property (don't do this in a rural area during high fire risk), there shouldn't be any legal repercussions. That said, it wouldn't be at all a bad idea to notify your neighbors that you're testing safe and legal rocket motors, just so they don't call the emergency responders when they hear the test. This kind of rocket can produce a very distinctive sound, as the chamber pressure produces oxidizer flow rate changes, leading to thrust oscillation that sounds very much like a pulse jet. This happens with liquid oxidizer, when the chamber pressure exceeds approximately 50% of the pressure available at the injector (which will always be less than tank pressure, due to throttling losses).

Some methods of rotating an image on screen use trigonometry to redraw after a small rotation. KSP probably can't use pre-rendering, because you need to be able to rotate the "camera" to arbitrary angles, but it's most likely also true that they aren't using the Unity physics engine to rotate internal parts of an engine that handles as a single part -- so something, somewhere, is rotating a 3D shape and rendering it at frame rate; given the presence of a math coprocessor (which does trig functions very rapidly by using an immense internal lookup table) built into all modern CPUs, it might well be a case of using TAN instead of -TAN or something similar.

Ah, I see now, the spiral on the center spinner is turning the wrong way, too. Seems to me the jets in my RO install do this, too. Maybe a sign or trig error in the animation?

It's probably emulating a stroboscopic effect. Ever seen the spokes in a stagecoach wheel seem to turn backward in an old Western movie? It's because, between one frame and the next, the spokes most almost to the old position of the next spoke. Vary the speed of rotation a little, and the fixed frame rate of the movie camera will make the wheels seem to spin forward, normally (at very slow speed), slow down, stop, run backward, slow down again, and furn forward again as the rotation rate gives various almost, exact, and just over integer spoke spaces between frames. There are also a number of YouTube videos that show helicopters in flight with what appear to be stopped rotors -- again, the rotor speed (which is nearly constant in a properly operating chopper) happens to match up with the frame rate of the video camera (and the very short shutter opening in bright sunlight gives a sharp image even when the rotor is turning at hundreds of m/s at the tips).

In the MechJeb "settings" box, there's a "UI Scaling Factor" (IIRC -- I don't have the game open at the moment). Just enter a factor to multiply the UI scale -- for instance, 0.8 will give an 80% size UI (which is as small as I'd go unless you have a huge monitor and pixel count on tap). I've got mine at 0.9 at present, and it leaves a lot more screen real estate -- I can keep the "ascent guidance" and "edit ascent path" and still see the dV, Orbit Info, [X} Science Here and Now, and more or less make out the stock resource display (it goes under the main MechJeb window, which I haven't yet found a reliable way to relocate).

I'm playing in RSS/RO/RP-1/Principia (and a bunch of other mods pulled in by those or recommended in the Golden Spreadsheet). In RSS, you need a hybrid of the old-KSP "burn vertically to some altitude, then start tipping" and the current gravity turn, along with some specific guidance late on the way -- because most craft flying to LEO burn continuously to apogee (which becomes perigee after burning some more to raise the perigee above the atmosphere). The manual pitch program in MechJeb's PEG ascent guidance does that -- burns straight up for a while (recommended, to around 100 m/s), then does a "by the clock" tip-over, which, if set up correctly, will segue into an "unguided gravity turn" if launching to "current inclination" -- that is, launching due east and letting gravity turn your path southward (or northward, if you're at Woomera or other southern hemisphere site). Regardless, I found the cause and solution of the problem (though I still consider it a bug, in that MechJeb's PEG module doesn't warn for an invalid entry). With my four stage rocket, I'm not allowed to enter a stage count of "4" in the "Num Stages" field (just above the button to "Reinitialize Stage Analysis") -- apparently, I have to enter "2" there (despite the fact that Orbiter One needs all four stages -- Tiny Tim boosters, LR-79 booster core, 2xAJ10-37 stage, and final 1xAJ10-37, which apparently will have a few tens of m/s to spare at a 230x230 km orbit). Do that, even after launch, and the vertical ascent countdown picks up counting down from clamp release, manual pitch program engages, and when its countdown elapses, MechJeb transitions to "unguided gravity turn" as it should. In the process, I also found a setting that lets me shrink MechJeb's UI, so it doesn't cover 60% of my KSP window when I'm flying an orbital ascent...

If you were to install Principia (n-body physics -- orbital perturbations, no SOI boundaries, actual LaGrange libration points and chaotic orbits) you'd have north at the bottom again. Or maybe Principia just expected me to rotate all my control parts 180 degrees?!

If you think KSP should be more realistic, have at it! Download and install 1.3.1 (available at no extra charge if you bought the game from the KSP web site, and I've read there are ways to get old versions if you bought form GoG or Steam). Install Realism Overhaul. Play away (oh, requires about 10.5 GB RAM to load, at least in 64-bit Linux). You'll start with the tools to make basic propeller and jet airplanes, and 1940s technology sounding rockets; even though the calendar will say January 1, 1951, it'll be more like early 1946 (you have access to a bunch of -- presumably captured -- A-4 rocket tanks, engines, fins, and guidance units). You'll spend hours and hours and hours gleaning science one or two points at a time, warping past weeks or months of construction time, and scraping every trying to keep your program solvent. When you manage to put a basic satellite into orbit, you'll feel a real sense of accomplishment; when you manage to fly past, impact, or orbit the Moon you'll be proud, and when you put actual crew in orbit, you'll have something to shout about. I've played RO exclusively for the past few weeks. I've bankrupted three programs and closed one because I had the settings too easy. I'm close to launching to (uncrewed) orbit in the fifth, having spent more than eight and a half game years (in a couple weeks real time) getting there from the first launch in April, 1951. In the current career, I haven't launched a single airplane, because I suck at landings (or design, I'm not really certain which) and I'm playing on "hard" setting, so no respawns, reverts, or quick loads. I've learned in some depth why modern commercial launchers like Falcon 9 use kerosene and LOX, rather than, say, inhibited white fuming nitric acid and unsymmetrical dimyethyl hydrazine (like the Apollo Service Module engine did), or hydrogen and oxygen like the Space Shuttle (hint: the answer in the latter case is "money"). It's more fun (for me) than the original game. Your mileage may vary, but if you like the idea of a logical tech tree (and have enough RAM to load all the mods), you owe it to yourself to at least install RO and give it a try.

I've spent about half the day today fighting what I'm now convinced is a bug in MechJeb. Last night, I tried to launch the vessel I last posted (Orbiter One) in my "Take Five" RSS/RO/RP-1/Principia career. Since I've managed to find information on what settings to use in MechJeb's Ascent Guidance module, I tried to launch with that (as I'll need it soon to launch in specific inclinations -- for sun-synchronous orbits, and when I'm ready to send probes to the Moon). Unfortunately, the first time I launched, MechJeb failed to keep close enough to the prograde vector, and the vessel broke up at around Mach 1.5 and 14 km altitude. A minor change to the vessel (increase the Tiny Tim boosters from three to six) and a change in MechJeb's AoA limit setting, and I ran a simulation to verify the changes without risking another vessel (and taking nearly three months of my contract period to do so). I found that now, for no reason I can find, MechJeb fails to start the timer to count down the vertical ascent time after launch before initiating the pitch over into the gravity turn. What should be a ten second delay (or whatever other value I input) fails to end after as much as a minute or more. This occurs, not just in simulation, but also with "live" launches in my sandbox. Naturally, I'm not very interested in expending 100+ days and around 10,000 (vessel and roll-out costs) in my career just to find out if the same thing happens there (I'm pretty sure it will). Above, you can see MechJeb reporting "Vertical ascent 15.00 s" -- still, more than a minute into vertical flight. MechJeb is working for some things; after starting, it stages the launch clamps once the core engine comes up to thrust, ignites and stages away the Tiny Tim boosters.

I'm running 1.3.1 RO(RSS/RP-1/Principia). I've launched to orbit several times in previous careers with manual or partially manual control. My current vessel is this one: This is a single LR-79 with dual LR-105 verniers, and (currently, upgraded since the photo) six Tiny Tim boosters to give a thrust aid while clearing the launch clamps. Upper stages don't matter for this, I don't think, but second stage is two AJ10-37 with nitrous oxide RCS, and inside the fairing is a single AJ10-37, also with nitrous oxide RCS, pushing a Sputnik PS-1 with four Sputnik antennae plus Geiger-Mueller counter and four tiny solar panels. Even with the low SLT, there ought to be (and according to MechJeb on the pad, is) plenty of dV to make LEO -- but that's not the problem. When I launch, MechJeb correctly auto-stages the launch clamps (once I figured out that the Clamp Autostage field isn't percent, it's a fraction, so .95 means 95% thrust, not just under 1%), ignites the boosters, and then stages them away after they burn out -- but doesn't start its own timer that should initiate the pitch program to start the gravity turn after (zero, ten, or fifteen) seconds from clamp release. Instead of counting down, the status displays "Vertical Ascent 10.0 s" (or whatever value I've input) for a minute or more as the rocket ascends vertically, until I revert the launch (I'm testing this in sandbox, after noticing the problem in my career at the cost of a launch vehicle and several simulations -- no reverts there). Reinitializing stage analysis changes nothing. Here, I had selected a 15 second delay on the pitch program, and as you can see, the MET shows 1:08 and MechJeb is still waiting to start the pitch program The last time MechJeb actually did initiate the pitch program, pitch failed to follow the velocity vector closely enough after transition to PEG and the vessel broke up due to aero forces when it reached ~12 degrees AOA at around Mach 1.5 at around 14 km. Since that launch, after reducing the amount of permitted AOA to 7 degrees, MechJeb hasn't even started the pitch program. Restoring the default 10 degree value changes nothing. My install was done based on @Bornholio's Golden Spreadsheet, so far as CKAN would let me follow it (at one point, CKAN installed a bunch of dependencies much earlier than they appear on the sheet)and everything else seems fine within the limits of performance of my computer (4 GHz isn't as fast as it seemed it was going to be, by the time you add FAR, E.V.E., and so forth), though I'll note that I haven't been happy with MechJeb operation at any time since installing, and had previously chalked it up to my own inexperience (until installing this RO/RSS/RP-1/Principia game, I'd run stock with only Better Burn Time). Even now, given I haven't done anything beyond LEO and then with satellites that had little or no ability to maneuver and/or ran out of battery in a few orbits, I haven't had any need for MechJeb other than to try to launch into a specific inclination or altitude -- I can manually pilot into orbit about three times in four with as little as 9500 m/s on the pad, so when MechJeb misbehaved, I assumed I'd set something wrong, reverted, and relaunched on manual.

The three angles of any triangle sum to a flat angle, aka half a full circle -- this is provable, though I don't know that I could reproduce the proof (a simplified, less rigorous form: the three angles must close the triangle, hence all three must combine to return to the original line, hence a flat angle). In an equilateral, by definition, all the angles are equal, so each is one third of that flat angle; therefore, the three equilaterals constructed as illustrated must produce a flat angle (1/3 flat angle, times three = flat angle). This proves that the line segment from the leftmost vertex to the rightmost is straight (i.e. no infinitesimal angle at the middle). And a straight line passing through the center of a circle is the definition of a diameter. Extend the construction to the full six equilaterals, and you'll have constructed six diameters of the circle, all of which are provable by the three triangles that define them. Put another way, the construction you have there is halfway through the construction whose goal is to create a regular (inscribed) hexagon.

You used r in your construction. No proof needed. You have r from center to circumference, and two points r apart (straight-line distance, not measured along the curve) on the circumference, therefore (by definition) the three points form an equilateral triangle. Or are you asking me to prove that six of those make a regular hexagon? The construction is commonly done with short arcs, but it can be done with full circles; proof of their consistent radius is that they all intersect at the center of the starter circle.

I looked at the Gamma engines (the ones that propelled Black Arrow), but decided kerolox was a better choice. I understand the decision behind using HTP as oxidizer for Black Knight and Black Arrow: installing a LOX production facility at Woomera would be a PITA (they ran on generators back in the 1970s, and liquid air distillation takes lots of power), but an oxidizer that's mostly water, even if it does decompose exothermically and (after catalyzation) ignite spontaneously with kerosene, does nothing good for your system Isp. A little shot of TEATEB gives the LR-79 ignition characteristics like a hypergolic motor (SpaceX still uses TEATEB to ignite Falcon 9 engines -- a shortage of this ignition fluid was responsible for loss of the core booster from the first Falcon Heavy launch).

Last night and this evening, in my 1.3.1 RSS/RO/RP-1/Principia career, "Take Five": I designed this career's first orbital launcher and its payload. Determined not to make the mistake from the last couple careers, of trying to jump the gun and launch to orbit with alcohol-burning engines (which have relatively poor Isp, requiring very large rockets to provide the 9200+ m/s required to orbit Earth, after accounting for gravity and steering losses during launch), I stubbornly held out for kerolox. Over the weekend, I unlocked the LR-79 kerolox engine, as well as the next step in hypergolic burners, the AJ10-37. Both of these engines have gimbals, but a single engine booster requires something more for roll if it doesn't vector thrust with jet vanes like the A-4 and RD-100 series. In this case, that the LR-101 vernier. In the most common form, these have single-axis gimbal over 60-something degrees, allowing a small continuous-burning engine to provide roll control for a booster. This stubby little thing (which masses just over 54 T on the pad) is Orbiter One. One LR-79 and two LR-101s, three Tiny Tim boosters to give a thrust spike when the clamps open. Second stage is a pair of AJ10-37, and has a nitrous oxide RCS system for ullage and after-burnout attitude control. The third stage (inside the fairing) lacks roll control, with only one AJ10-37 (roll really isn't needed by that point). Gravity losses are pretty high in the first minute of flight, but according to simulation, by the time enough fuel has burned off to give a 1.4 TWR, there's still 9200+ m/s, which is enough for a rocket with that TWR to launch from Canaveral to a polar orbit. Construction and simulation testing was funded by accepting both "first artificial satellite" and "first solar powered satellite" contracts -- the Sputnik PS-1 core inside has four first-gen solar panels, which should produce just about enough power to keep the Sputnik operating indefinitely, possibly even recover slowly after science transmission depletes the battery. In addition, there is a Geiger-Muller counter, an early TV camera, orbital perturbation experiment, and of course the telemetry analysis native to the Sputnik. My main concern with this launcher is the reliability of the engines -- LR-79 and AJ10-27 are new to the program, and in simulation I had multiple failures (including an LR-79 that exploded at ignition). R&D is working on the engines, and hopefully they'll be better by the time my 104 day construction period has elapsed.

Generally, the lighter your plank relative to its area, the better it will "glide" in this kind of test. I've seen balsa wing panels from dime store gliders and Sleek Streeks get 4:1 or better. I'd suggest either the softest, lightest piece of balsa sheet you can find at the local hobby store, or a piece of foam cut from a picnic plate or the lid of an egg carton as having the best strength to weight ratio in this size range. If you really want to stretch things, you could get some glue, make up a frame (just the outline of a rectangle like your paper scrap, with two or three cross braces), and attach a single layer of holiday wrapping paper or model airplane tissue. The result will be lighter for its area than any solid material thick enough to be reasonably rigid, and ought to outperform anything heavier. Look on YouTube for a video on "ten minute squirrel" to see how to build the frame and cover it at the same time. It's actually possible to build an airplane using wings that work like this -- you'll need stiff rods running through wire loops on one surface of the wing frame, and the rest of a dime store rubber power model (for propeller, rubber, and tail surfaces). Be prepared to adjust the balance quite far from where it would be with t a fixed wing, and don't expect it to glide like a sailplane, but it can be made to fly.

Yeah. These are the same people who wonder why leaning way, WAY out on a ladder while cleaning their gutters lands them in the ER, and then pull a nearly identical stunt the next summer trying to adjust their satellite dish. The ones who'll give their social security number and mother's maiden name, as well as their own full name, driver's license, and bankcard number(s) to a random caller who claims to be from their bank (without actually saying which bank). The ones who'll activate remote desktop when "Microsoft Support Services" calls them out of the blue.

Loupes rarely if ever exceed 20x. There's a van Leeuwenhooke microscope in a museum in Netherlands (one of his later ones, using a simple glass bead for a lens -- but that change was to prevent evaporation, more than for any optical advantage) that's good for 600x. It's easy to get to 200x with a water drop, and with a little work you can make water drop or glycerin lenses good for 300x or higher. Magnification enough to see blood cells and zooplankton is a huge step from a 20x loupe, and it's one that could have been taken in Neolithic times. Add this to the Baghdad battery, the Antikythera computer, and Heron of Alexandria's command of steam and air pressure, and it seems if there'd been communication to match the inventiveness, modern times could have started in the first or second century of the Common Era. What the Egyptians, Persians, Greeks and Romans mostly lacked was the printing press.

Nice, @cubinator! I thought there was something like that, just couldn't recall it. Seems to me someone actually modded in a Von Neumann (self-replicating) probe and sent it to Alpha or Proxima in that mod.

I've got 100% stock science and career saves that were started in 1.2.2 and now run in 1.4.3. I also had trouble with mods not working the first time I set up RO, but I went back to @Bornholio's Golden Spreadsheet and installed in the order shown, and (aside from a few minor bugs like crewed missions setting records much higher/faster than the crew actually went) the game plays well. You have to install 1.3.1 for RO to work at present, but that's a step forward from 1.2.2, and if you bought the game from Squad/Take Two or Good Old Games, you should be able to download older versions at no additional cost (not sure how or if you'd do that with Steam, sorry).

Wow, lots of stuff since I was last on, and I didn't read every word of every post, but I'll pick one thing from way back up near the beginning, and then one from the end: First, a microscope. Anton van Leeuwenhooke (various vesions of the spelling of that Dutch name) made the first microscope,. without any glass at all, in the 17th century. You can replicate it easily enough -- use a needle (even a bone one made by a caveman will work) to poke a hole in a flat plate of some kind, then get a drop of water to lodge in the hole. The smaller the hole/drop the better for this. Make an attached stage to hold your specimen, stand in direct sunlight (it'll be the brightest light you can find) and get your eye as close as possible to the water droplet. After a couple years of improvements, van Leeuwenhooke apparently (based on his drawings of "animalcules" seen in drops of pond water) got magnification as high as a couple hundred diameters. He was able to see blood cells, and if he'd known about staining he could have seen chromosomes in cheek cells with these simple microscopes that anyone could make. And with that technology, you could bootstrap blood typing. Take blood samples from two people, mix them, and look at them with the microscope. If you see the blood cells stacking up like little disk magnets, the two samples are different types; if you don't, they're the same (ABO) type. You wouldn't be able to tell only from this which was A, B, or O (though if you knew what ethnic group your cavemen were ancestors to, you could make a pretty good guess), but this is essentially the "cross-match" step that is always done during a transfusion if you have two minutes before the patient bleeds to death. Rhesus factor typing and the other factors that are recognized today are much more complicated to detect -- but transfusions within a small population of cavemen would be simplified by the strong likelihood they're all the same (ABO and Rhesus) type anyway, because all are close relatives with little long-range interbreeding. Transfusion of whole blood, regardless of typing ability, probably not going to happen. Stainless steel and good quality glass are required to handle blood without clotting, as are anticoagulants (the simplest of these is sodium salicylate, theoretically possible to refine from willow bark). Centrifuging blood to produce plasma is realistically possible, however, and plasma could be transfused using materials like snake fangs for needles and animal bladders for pumps.

The general principle of lift generation of the bullroarer can be demonstrated easily enough. Take a piece of flat balsa (like one wing from a dime store glider), hold it level, and just release it a little forward. You'll see it spin rapidly, with the leading edge rising. This occurs because the center of lift of a flat plate is well ahead of the center of the plate (where the center of mass resides). The plate builds enough momentum to continue to flip through the stalled regime, until it starts to develop lift again with the other side up -- which supplies more lift ahead of the mass, and continues or increases the rotation (you could also see the plate as flying through a very tight loop, with its air-relative velocity always generally toward the leading edge, so that it never stalls). I don't understand how a bullroarer can reverse its rotation and still lift upward, however -- by the time the rotation has built up some speed, the Magnus effect contributes substantially to the total lift, and reversing the rotation ought to drive the paddle into the ground. Perhaps if the second view of the lift (flying through tight loops very rapidly) is correct, the loops can reverse and produce near-zero net lift, so the force of the cord holds the thing up. The noise comes from pressure excursions as the airflow over the plate changes rapidly -- sometimes the pressure is very high on one side, and very low on the other; other times, it's nearly the same. This will cyclically alter the pressure (which is the definition of sound), and since this is happening only a few tens of times per second, the pitch of the resulting sound is quite low.

I'm not sure I understand. Are you looking for a sky as seen from another star, or additional solar systems to send probes and ships to in RSS? You do know that it would take thousands of years for the fastest probe ever launched (Voyager 1) to get to the nearest star (Proxima Centauri), right?

Have you tried Realism Overhaul? You might get bored out of your mind during the longish "grinding sounding rocket contracts" period before you can launch to orbit, and yes, there are some bugs -- but it's so much MORE than the stock game. Eight planets (remember, Pluto got demoted?), dozens of moons, a number of asteroids (a few of which actually have gravity). It's a real challenge to launch a small satellite with ethanol-burning engines, or even with the early kerosene burners. Getting a crewed mission to the Moon is a really, really big deal (far more so than in the stock game -- for a start, you need something like four times the dV to get to orbit, and almost five times as much from LEO to Moon impact vs. LKO to Mun impact). Life support, Flight Test (which makes engines fail occasionally, but less so the more of them you fly), Kerbal Construction Time so it takes months to build a sounding rocket at first -- if you can launch to orbit before 1958 in Hard mode in RO, you're a better manager than I am...

America's first crewed orbital launches (Atlas) used an LR-79 with a pair of LR-89 that were dropped partway up -- the LR-89 being the sea level optimized version of the LR-79. I don't know that a single LR-79 can lift a Mercury capsule and enough upper stage dV to get it to orbit -- and a cluster of them is carrying too much weight. Shorter-burn boosters are likely the better solution, as they were in 1962. If you don't have the Atlas decoupler, you could (at somewhat higher cost) use side boosters. Worth noting that Nathan Kell (in his Rusty RP-1 series on YouTube) launched a lot of LR-79 sounding missions before attempting orbit and Lunar flyby/impact with them. Having lots and lots of flight data is a good thing -- doesn't eliminate failures, but it cuts them down to a minimum.