Zeiss Ikon

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About Zeiss Ikon

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    Spacecraft Engineer
  1. As I read the mentions of this, it requires editing the save file.
  2. On the basis of a couple hundred hours flying radio control models, landing is the hardest part of flying. Aerobatics are easier. Soaring is easier. Taking off is only hard if your aircraft is underpowered. But landing is always stressful.
  3. I'm aware of the cap-lock setting (and don't use it much, preferring light taps on the keys in regular mode). The problem I had in this case was that the combination of "point to target" on both transfer stage and lander led to the two circling each other and the rotation rate building up as I tried to translate the lander to get the stack-to-be straight enough for the docking clamps to latch. I'll find a suggestion thread to repeat this, but it would be very, VERY helpful if there were some way to indicate pitch and yaw axes on the spacecraft in the external view. The nav ball can say my vector is perfectly aligned, but if I'm approaching at an angle, I won't get a latch -- I'll get a bump that adds tumble to an unstabilized part, or a "tail chase" if both parts are on target point. And when I try to straighten out, the nav ball is no help. Yes, I know, there are mods for that, relative to docking -- but what I'm suggesting is that the ships have a clear indicator of pitch and yaw axis, which would be useful for any maneuver -- like getting into orbit the correct direction when launching from Mun, or launching to polar orbit from Kerbin.
  4. Following up on this, when I redocked my lander (Mk. 1 command pod with Clamp-o-Tron Jr.) to my transfer stage (Mk. 1-2 command pod with Clamp-o-Tron Jr., even though the nose has room for the 1.25 m port), I found the flow priority was no longer what I set in the VAB -- the transfer stage's 2.5 m monopropellant tank had the same flow priority after redocking as the lander's four Roundified tanks, which would reliably result in the Roundified tanks (4x60 units) running dry while there's lots of fuel in the 2.5m tank (750 units). Oddly, at some time (possibly a game restart) after manually adjusting the flow priority, I found the transfer stage tank had regained its higher priority, plus the 10 priority units I'd added in my manual adjustment. I also found that this particular lander does use a lot of RCS fuel when docking to the transfer stage, even when the transfer stage is stabilized; apparently, the RCS isn't well balanced or my movements are fighting with the "point to target" SAS setting. Next time I fly this vessel I'll try to remember to set the transfer stage to "point to target" and then switch it back to "hold orientation" so I can dock to it without it turning to follow my every correction. Maintaining pointing has worked well in the past, but I've never had vessels with the mass distribution (base-heavy) that these do.
  5. I'll try to give this a test, but it'll have to be during an actual mission -- Val has another date with an asteroid tonight.
  6. Well, that was the idea. Of course, by the time Congress was done with it, the Shuttle cost more to operate than expendable rockets to do most of the jobs it was intended to do. Why would you need wings and a crew of seven to launch an interplanetary probe? After Challenger, they retasked it for only missions that required crew, and ISS operations -- and it still cost more per payload ton than it would have to use (for instance) a Titan with its man rating recertified and restart the Apollo capsule line. Not to mention that even before Challenger, they were spending delta-V after reaching orbital height and velocity to ensure that the ET burned up rather than leaving it in orbit, where it might have been possible to repurpose the spent tanks...
  7. Hmm. I used to use manual shutoff before I discovered flow priority -- problem is, I had several instances (in my sandbox game) where I "ran out of monopropellant" only to later discover that I had about 2/3 of my original supply remaining in tanks that had been shut off. I suppose it's possible that I burned a lot more of the lander's monopropellant than I thought doing the turn-around and redock to the nose-to-nose configuration (during that operation, the transfer stage is unguided -- no probe core, no crew -- so it tumbles slowly). Once redocked, the transfer stage RCS tank is available again, which prevents me from noticing the state of the lander's tanks. I might have to reexamine my "no automation" policy for my science save -- or just put another command pod on the transfer stage so it can stabilize on a gyro heading and/or hold "point at target". That would save time as well as RCS fuel. Docking is fairly easy if both vessels can maintain target pointing; it's not terrible if one just holds orientation -- and it's a PITA if one is tumbling free (because every port bump that doesn't latch adds to the tumble). That transfer stage isn't intended to be recovered; if I put a command pod on it, I'm committing to at least bringing the command pod back (or I have to redesign the lander for one or more additional seats, and then scale up the launcher for the extra mass). OTOH, it is intended to bring the lander's ascent stage back to Kerbin from wherever the landing was done, so having a kerbal aboard wouldn't be completely off the wall. Hmmm. Back to the VAB, I guess...
  8. A while back, I learned about setting flow control for resources that are shared over an entire vessel, such as RCS fuel. Today, however, I came to wonder if I knew what I thought I knew. My ship, Far Traveler, has a 2.5 m RCS tank in the transfer stage (250 units), four "roundified" external tanks on the lander ascent stage (60 units), and the usual 10 units stored in the command pod. On its first real mission, I never had a problem with RCS until after decoupling the transfer stage to test the lander during aerobraking -- and then I found out both the lander's roundified tanks and the small capacity of the Mk. 1 command pod were depleted. Now, either I ran everything dry just about the time I decoupled (unlikely, since I was turning off RCS between intentional uses to avoid having it cause orbit drift when used for stability, though I can't say I actually checked; last time I'd looked, after using RCS for a very, very small correction burn, there was about 40% left), or my flow priority (30 for the transfer stage tank, 10 for the roundified tanks, and -10 for the command pod's tank) worked backward from what I expect. Suggestions?
  9. Last night and today, Val continued her assigned work. (Science game) While Munar Lander Mod. 2 was giving journeyman service for voyages to Kerbin's moons, R&D had kept remarkably close-mouthed about what they were working on. They had gobbled up a huge quantity of data taken from three Mun missions and two multi-landing Minmus missions since the last significant spacecraft or launcher upgrade, and rumors had started to circulate that they were spending their time eating pizza and playing video games. None of this was connected with Jeb's puffy eyes and drawn look; after all, he was close with a number of the R&D types; legend has it he was recruited by Werner himself. However, with the growing awareness of the magnitude of the potential threat posed by the new type of body the astronomers call an "asteroid" (because no matter how much magnification you apply, it still just looks like a star in the eyepiece at the limit of seeing quality), an R&D spokesman was authorized to reveal the previously secret subject of R&D's late nights and Jeb's fatigue: Far Traveler. This vessel was originally designed with its sights on Gilly, Ike, Duna, and Dres. It has more than 5 km/s delta-V in LKO while pushing the heavy upgraded lander, and the transfer stage uses seven of the new Poodle engines to get maximum use from its fuel, while maintaining the ability to thrust at nearly 1 gee with full tanks. The lander itself is good for more than 1.2 gee, and was extensively hover tested around KSC during development. In order to assure the (6) boosters fall clear of the (7 tanks, 7 engines) core, and give enough thrust for positive liftoff, each booster has five Thud engines in addition to the Mainsail, giving this launcher a total of 43 engines (13 Mainsails and 30 Thuds) firing at liftoff. With the boosters pumping fuel into the seven core tanks, this launcher can circularize, even in polar orbit, with a restart of the booster core, leaving it on orbit with seven Poodle engines and enough fuel to run them for more than five minutes. By the previous standards of the KSP, Far Traveler is a monster -- but it gets the job done. Despite Jeb having done the testing of the lander and launcher, Val was selected for the first actual mission in this new vessel, because planetary missions are on temporary hold while the asteroid problem is evaluated. Asteroid are hers, for now. The selected target of her new mission was YMQ-666, which tracking showed was due to pass Kerbin within the Mun's orbit. Val was to attempt to get close enough to get a visual, and if possible rendezvous and return science data (ideally including a surface sample). Due to a miscommunication, she launched north, rather than south, but Mission Control recommended continuing the mission, so she burned to put herself into a synchronous orbit (same period as Kerbin's rotation, though not stationary), which after plane correction would cross the asteroid's path during its Kerbin encounter. Once her high parking orbit was established, Val made a large burn to completely reverse her orbit -- effectively, a 180 degree phase change, though at the apoapsis she had, the dV was hardly more than a Mun return. Once that was done, with the thought that she might actually be able to nudge the asteroid's orbit with her landing legs if she could park against it, she decoupled the lander and docked it back to the transfer stage, nose to nose, then deactivated the lander engines and flipped an all-important switch to reverse her controls, allowing her to fly by instruments with the same orientation she would have had in the command pod prior to decoupling. Then it was time to wait. After three orbits, plotting reported she had an intercept at a reasonable distance, and she made a burn to extend her orbit and correct her plane a fraction of a degree, then made two tiny correction burns (RCS only, with RCS shut off between burns to ensure it didn't cause drift) to give a final predicted intersect of only 2.1 km (albeit with 185+ m/s relative velocity). When she arrived at the intercept, however, there was nothing in sight. A rock estimated at half the length of the ship ought to have been visible, at least as a blinking dot, many kilometers away, but not only did she see nothing, the Tracking Station couldn't confirm a second object near her location. With the intercept passed (seemingly missed), and with nothing to show (even her science observations produced nothing new, since she was still in an orbit of Kerbin), she made a pretty small burn to lower her periapse into the upper atmosphere, and headed for home. On the first pass, she made a powered aerobrake with the transfer stage engines (testing a technique expected to be useful for future voyages), lowering her apoapse from 4000+ km to around 800 km in a single pass despite burning for less than a minute at 10% throttle, and without changing her periapse (selected at 55 km), thus demonstrating that repeated passes could be used if needed to control heating. On the next orbit (now just over an hour, compared to a full Kerbin day) she decoupled the transfer stage, still with 30% fuel, returned her controls to normal orientation, reactivated the lander's descent engines, and made a reentry burn test requested by mission control. Before burning out the lander's descent stage tanks (in conjunction with aerobraking above 50 km) she'd dropped more than 2 km/s velocity. She staged away the descent stage and found the ascent stage, now falling into somewhat thicker atmosphere around 40 km, was able to reduce velocity from just below orbital to about 1.3 km/s with use of only half its fuel. For the first time since the early orbital launches, she opened her parachutes without any loss of the ablation layers on her heat shield. Despite bringing back almost no data that R&D could use, she had learned things that Planning could turn into better future asteroid missions. One of these things, it was discovered, was that under circumstances yet to be fully defined, the plotting system at Mission Control could give a "ghost" position for an asteroid that had not yet entered Kerbin's sphere. In this case, it was found that, despite Tracking Center correctly showing asteroid YMQ-666 due for a Kerbin periapsis in 67 days, Mission Control's plotting system had shown it already beginning its encounter at the time of Val's launch. Technicians are on watch-and-watch until this problem is tracked down; in the meantime, priority is being give to another object, ASA-666, for which Tracking shows a Kerbin encounter due to begin thirteen days after Val's landing, and end thirteen days later -- but its Kerbin periapsis is zero, to the accuracy of available measurements. It appears this object may impact Kerbin. Fortunately, ASA-666 is tiny, what the astronomers are now calling Class A (the smallest current technology can detect in near-Kerbin space), with size comparable to a Munar Lander ascent stage and mass almost certainly less than the transfer stage and lander combined; it's very unlikely to do major damage, though it's uncertain what it might do if it strikes a population center. Val's next mission is to verify its size, if possible, and evaluate the possibility of deflecting it (or another object on a similar collision course).
  10. One of the earliest German (WWII or slightly before) helicopter designs used compressed air jets to drive the rotor so it didn't produce reaction torque, and hence could fly without a tail rotor. The air was pressurized by an aircraft radial engine driving a big centrifugal pump. As noted, the Harrier uses reaction controls powered by air bled from the engine compressor; there was also a research variant of the F-104 Starfighter that had a cold gas (i.e compressed nitrogen, in that case) RCS system for use with a rocket motor that could kick the jet to well over 30 km altitude, where the jet engine and aero control surfaces were effectively dead weight. The Isp for RCS propellant is consistent with catalyzed hydrazine -- but I guess we'd have to have Real Fuels to be able to use hydrazine as fuel with an oxidizer like nitric acid, or use high test peroxide as monopropellant and also as an oxidizer. But then we'd have to allow for boil-off of liquid oxygen on interplanetary transfers, and liquid hydrogen for nukes even on a Minmus trip. Easier to just let liquid fuel be liquid fuel, and feed jets, nukes, and mix with generic oxidizer to work in bipropellant engines.
  11. If you're sending Kerbals, you do. I've got a reliable Mun/Minmus ship that uses 1.25 m parts, but in order to reliably send even one Kerbal anywhere further, with capability to land and return, and do the mission with a single launch, I've had to build a monster with thirteen Mainsails and thirty Thuds burning at launch -- but it's got 5+ km/s dV from LKO, while pushing a lander that I'm pretty sure can land and return from any airless body in the Kerbol system with the possible exception of Tylo. And that's still all 2.5 m parts. Once I get enough 3.75 m parts unlocked, I'll be able to send the Mk. 1-2 anywhere in the system on a single launch, I think.
  12. Truer words never spoken. Says the guy who has, over time, stranded multiple Kerbals in various orbits...
  13. I think that's more of a tumble -- you can't start one of those after your get into heavy heating, at least with a simple command pod, because it's too stable in the base-first position. I'm talking about a roll (E or Q keys), which seems to even out the heat a bit and can by started after the capsule is too stable to do more than tip a bit under pitch or yaw command. Okay, I may have gotten that from trying to bring in a second goo canister or thermometer reading from the same location -- and then quit trying because I was trying not to lose the science I'd gone clear to the Mun to get. I'll try bringing the science inside next time, so I don't chance burning it up.
  14. Yep, it was Scott Manley's videos that got me to buy the game, too. After trying the demo for a week or so, of course. An online tutorial showed me how to build a rocket with demo parts that could make orbit -- and I was hooked. I bought the game in December, and I've flow many missions to Mun and Minmus, as well as one Duna flyby (in Sandbox mode). I'm currently pursuing a Science game, and looking forward to the day I feel confident enough to try Career.
  15. Yesterday, i had about an hour to play, and I flew an unusual mission. (Science game) With Jeb having recently managed to get himself to the Mun, Val started whining about being grounded. In fact, she whined loudly enough that the Planning Committee came up with somethign special just for her. The most recent mission to Minmus had generated reports of "mystery objects" showing on the orbit planner displays. One of these was fairly close to Kerbin -- a little closer than Minmus -- and the Planning Committee decided to try to send a ship out to get a close look at it. Valentina got the seat for this one, and climbed into the reliable Munar Lander Mod. 2, well proven to have the delta-V to get to Minmus, capture, and even deorbit with the transfer stage. Complicating things was that the mystery object selected was far out of the ecliptic, relative to its distance; Val would have to launch into a polar orbit, close to the correct time of day, to be able to reach it without dV prohibitive plane changes -- and no one had ever flown into polar orbit previously (though Jeb had flown suborbital missions near, to, and over the North Pole, giving a good idea what was needed. At the best estimate time, Val lifted off and promptly rolled five degrees, then started to pitch (normal launch profile is to yaw directly to the east, to take adavantage of Kerbin's rotational speed). The rest of the launch was completely routine, except that the combination of losing 300 m/s from Kerbin's motion, and in fact having to kill that velocity to get a polar orbit, meant that the launcher used more fuel than usual getting to orbit. This was expected, however, and Val's early gravity turn saved enough that she was still able to circularize without using any more fuel than was considered normal for an eastward launch. One partial circuit of the 130x130 km orbit brought her into position for her ejection burn toward the mystery object, which had to be combined with a mild plane change, as the launch timing hadn't been perfect. Then it was time for the waiting -- five days to apoapsis. It was not unexpected that the object had moved before Val got close, but how far it moved was instructive, as was the fact that it wasn't visible with on board instruments (strongly implying it was tiny, by cosmic standards). Then came the breakthrough: the same intern who'd taken a tape measure to the VAB during the booster staging crisis in the early days of the Munar Lander series had been assigned to distribute coffee in Mission Control -- and (she said) while trying to zoom in a screen for a better view of Val's track, discovered that the mystery object was trackable. These objects had previously never been tracked, apparently because no one in Mission Control had thought to try. By the time Val had returned to Kerbin (after the decision was made not to attempt to pursue a rendezvous with the original target object -- too far and too fast, she'd have never gotten back to Kerbin with the fuel available), the Tracking Station (once they knew it could be done) had discovered and plotted orbits for a round dozen of these objects, few if any as far from Kerbin as twice Minmus's orbital distance -- and one projected to pass Kerbin at a distance of only 900 km in about half a year! Suddenly the whole focus of the space program was changed: if these mystery objects could approach Kerbin that closely, there was no good reason they might not actually hit the planet. It suddenly became a priority to know what these things were, how big they were, and if there was a way to steer one away if it was detected on an impact orbit (in time).