Zephram Kerman

I tried direct descent for my first attempt. Complete de-orbit burn at the starting 100k altitude, drift all the way down with a few horizontal bursts to cancel lateral velocity ahead of time, then braking burn like crazy for the last 4 km. The result was so bad I didn\'t even bother with a screen shot.

In hindsight, that would have been much less terrifying for my little kerbals in the can. Hey good shot!

Here\'s my entry: 134.5 kg fuel remaining. My trick was to start with a short retro burn to descend; basically a modified transfer orbit. The remainder of the retro burn was done at 5 km altitude. After that, it was a short fall with a few horizontal bursts to trim the remaining lateral velocity, followed by a white-knuckle burn just before impact touchdown. We estimated the final burn by comparing altitude to speed; the target was Vertical Speed = Altitude / 20. Upon impact touchdown even Bob smiled, after a short bout of screaming. However, Jeb was concerned about being double-parked back at KSC. So, just to see if I could do it, I decided to send them home. Umm. Bob wants to go buy a lotto ticket, as soon as he changes into a clean spacesuit.

Ok, here is a first run of the data you requested. This experiment combined two subjects of interest: the effect of gravity turn start aggressiveness, and Specific Energy just prior to circularization. The process for each run was to set up MechJeb for 75.5 km orbit, with Turn Start Altitude at 8 km, and the 'Turn Shape' slider at about 33%. I then turned on MJ Surface Mode at 90° pitch from launch until 8 km. Then I changed the surface mode pitch to the test value, and hit 'execute' at 8 km. When altitude reached 10 km, I switched on MJ Ascent Autopilot using the values set up earlier. Upon reaching 75.0 km, I took a screenshot to record the velocity and altitude, for use in calculating the Specific Energy. I had trouble with the Excel graph not displaying the data point for the 80° run. Those values are: S.E. 1,133,270.355 J/kg, Fuel remaining 84.6 kg. Also of interest are the twin 60° data points; the lower-performance one was a MechJeb-only ascent as a control group, while the higher-performace one was my attempt to match it using Surface Mode to be consistent with the other runs. The results are not very dramatic. The S.E. and fuel varied only slightly, probably within the precision of my button-click timing. I zoomed in the graph for better detail, but really it\'s almost flat. So it appears the aggressiveness of the initial turn is not as important as I had thought. If this is true, it brings more evidence to support PakledHostage\'s theory: I think what we really need is a repeatable way to evaluate more curvature options than are available with MechJeb. I\'ll hold on to the raw data for a while, just in case anyone has questions or I\'ve made a mistake somewhere.

Challenge accepted. I plan to experiment with some ascent profiles using 8km turn start altitude, manually varying the aggressiveness of the turn start, and then a consistent MechJeb curve for the remainder of the ascent. For your data, I will add to this a measurement of S.E. before and after circularization. That\'s awesome.

Maybe he\'s going for a speed run? Going 'straight' is of course much less efficient than a proper transfer orbit. But hey, it\'s just a game! Do what\'s fun. So, to answer your question. Basically, it depends on the time it will take your ship to get there. So first figure out the flight time. Then figure out how much Minmus will move in that time.

Alternatively, you can: hold down the left Alt key, in the num pad type 0176, then release the left Alt key. You should get this ° If you\'re Bob Kerman, you type all special characters this way, and have the codes memorized. And you use a slide-rule. :

Not directly. If you\'re on an equatorial orbit and looking straight down, you\'ll miss it. I had a lot of fun using R4m0n\'s muon detector mod. Even with that thing, some of them were very challenging.

Hey, that\'s teh sexeh! Much more detail than I\'m used to seeing. The colors look a little bit loud, but they\'re also intuitive, and that\'s worth a little glare. Is it just me, or does the map data look like it\'s stretched into a too-large image?

This is one of the technical issues which occupied the brightest minds of Kerbin for several lunch meetings. Using much higher math, three slide-rules and a potato, the KSC engineers came up with a rule that is usually understandable by at least 1/3 of crewmembers: In other words, the Mun (and so far, in my experience, this also applies to Minmus) rising over the horizon happens at just the right time to assure a 'pretty good' trajectory for Trans-Munar Injection.

Very nice. I always prefer to see the 'do this' version instead of the 'don\'t do that'. Positive reinforcement helps to set the tone for the community. Just a couple of questions, if I may: Could the guide mention the 'Insert Quote' link is available while writing your post? This makes it easy to individually quote multiple people from a thread. What is TL-DR?

I like to imagine them as being something of a hybrid between plants and mammals, very similar to the Supox of Star Control, but based on some other plant family.

Wow!

Deep Impact. (Sorry, I just couldn\'t resist.)

Thanks for the compliments everyone. I\'ve been wanting to investigate gravity turns ever since we tackled the Goddard challenge. So putting some time into it was just fun for me. (That, and I needed practice with Excel graphs.) I\'m just speculating here, but the ideal curve probably varies according to both thrust/weight ratio and coefficient of drag: • High TWR and low drag would probably balance out. • If both TWR and drag are high, that craft would prefer a steeper ascent curve, to minimize air drag. • If both TWR and drag are low, that craft would prefer a shallow-ish ascent curve, to minimize gravity drag while slower than terminal velocity. So instead of being a speed limit, I\'m starting to think of terminal velocity as the target speed. Go full thrust whenever possible. If speed > Vt, pitch up (or throttle down if already vertical). If speed < Vt, pitch down (but only down to horizontal). Adjust this to compensate for your craft\'s particular coefficient of drag. Does this sound right to anyone else?

Finally! Collected a bunch of data points, using two of MechJeb\'s ascent profile settings. Lots of data, so I made a graph. Sorry jqhullekes, but it turns out the right side of the \'Turn Shape\' slider is toxic! (Basically, as the slider gets moved to the right, for steeper angles, the graph peaks move left towards ground level and below it.) On the other hand, if your manual curve shape works better than MechJeb\'s, it might be just fine. The best shape for MechJeb seems to be around 1/3 from the left. With this setting, and a \'Turn Start\' altitude of 9 km, my best run was 84.7 kg fuel remaining.

Almost on topic: for monitoring my system stats, I really like Samurize and SpeedFan. Both are very useful, and work together beautifully. With a bit of time and effort, I got them to present a little histogram of the last 10 minutes that floats in the corner of my desktop.

Hey that\'s pretty gewd! Relatively concise, considering the quantity of concepts being presented. I\'ll look forward to reading your take on orbital mechanics. (That\'s a pretty huge area all by itself!)

Oops. I missed the poll deadline. FWIW, I prefer the first map with five continents. It\'s already won by a single vote. But, I\'ll chime in anyway, just to make it decisive. (Be grateful I didn\'t vote it into a tie! Mwahaha!)

Just in case someone reads this who doesn\'t already know: the usual workaround for memory leaks is to close and relaunch the program after too much time has gone by. This has the effect of telling the computer to de-allocate the memory that was being wasted and makes it available again. Sometimes it\'s necessary to reboot, but that\'s relatively rare.

Here\'s my entry: 83.1 kg (dV=4369 m/s), using MechJeb to do a shallow gravity turn starting at 12 km. I experimented with different profiles by clicking the \'edit path\' button and adjusting the \'turn start\' altitude and \'turn shape\' slider. Here\'s the data: Fuel Remaining (kg) After Various Gravity Turns [table] [tr] [td] slider position (%) 25 (shallow) 50 (standard) 75 (steep)[/td] [td]turn start (km) 8 10 12 65.6 kg 83.0 83.1 75.6 71.2 65.6 42.3 36.9 31.2 [/td] [/tr] [/table] The results varied wildly! I should collect more data between these points to better spot the trend. But it\'s getting late for today. At the moment, my gut says we\'ll find the \'sweet spot\' where gravity drag and air drag are in balance. Perhaps we\'ll find out tomorrow.

Congratulations! Rendezvous is one of those extreme challenges, especially if you manage to do so without things spinning away. Good job!

By the way, it\'s possible to move a craft from VAB to the space plane hangar by moving or copying the .craft file from /KSP/Ships/VAB to /KSP/Ships/SPH. So if you really, really, want something on your space plane to have radial symmetry, build that section in the HAB and then move the .craft file to SPH and finish the rest of it there.

Lots of good stuff in this thread! There\'s only a couple of other things I can think of to suggest: • it is possible (although tedious) to manually match the map and camera views by comparing points of reference, like Kerbol and the Murky Way / nebula thingy; • install MechJeb and use the Smart A.S.S. mode to get used to the various directions like Prograde, Radial, Normal, etc.; • when doing a plane change, burn towards Normal or Anti-normal, but be aware this direction changes throughout the burn, so watch that the prograde marker stays on the edge of the nav ball; • during vertical descent, it helps to rotate the camera (or ship) so that the nav ball matches what you see.