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Everything posted by Tarmenius
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Optimal Ascent Profile for this spacecraft
Tarmenius replied to PakledHostage's topic in KSP1 Challenges & Mission ideas
Hmm, you\'re probably right about that. Instead of a two-stage rocket, I think I\'ll test the trust-to-weight ratio variable instead. Have one rocket with a high ratio and one with a low, then see whether their ideal ascent profiles are much different. And I\'ll definitely let you guys know what I find. -
Optimal Ascent Profile for this spacecraft
Tarmenius replied to PakledHostage's topic in KSP1 Challenges & Mission ideas
Yes, very nice work, Zephram! Now I\'m curious about whether different rockets really do have differnt ideal ascent profiles. Maybe I\'ll try a simple, two-stage setup and see how it compares... -
KGSS: Determining Composition of Minmus surface
Tarmenius replied to togfox's topic in KSP1 Challenges & Mission ideas
Good idea! I think I\'ll set that as my goal for the next attempt. MOAR BOOSTERS and aim for the ice! -
KGSS: Determining Composition of Minmus surface
Tarmenius replied to togfox's topic in KSP1 Challenges & Mission ideas
Well that was pretty fun, thanks for putting this out there. I didn\'t accomplish nearly the impact velocity you two have, but I only sent up a small 'unmanned' rocket for proof of concept. For my first attempt, I ended up with an impact velocity of 2512 m/s. -
Optimal Ascent Profile for this spacecraft
Tarmenius replied to PakledHostage's topic in KSP1 Challenges & Mission ideas
So, I messed around with various profile configurations using MechJeb and the best I came up with had 85.1kg remaining fuel. That profile was damn close to my original one but with a sharper turn around 25km: 70deg @ 8km, 60deg @ 15km, 45deg @21km, 30deg @ 28km and 25deg @ 32km. Gravity Losses were 1426 m/s (32.7%); Drag Losses were 826 m/s (18.9%); and Steering Losses were 33 m/s (0.8%). From there, I tweaked the Turn Start Altitude alone to see the effects it would have. Lowering the TSA resulted in greater Drag and Steering Losses with lesser Gravity Losses. Unfortunately, the lesser Gravity Losses were not enough to make up for the greater Drag and Steering Losses. Raising the TSA resulted in lesser Drag Losses, but greater Steering and Gravity Losses making another net increase in fuel consumption. Then I tried mixing it up a bit. Lower the TSA, but make a steeper ascent profile. Raise the TSA, but make a more shallow profile. Nothing worked. The closest I got in those attempts had a remaining fuel level of 80.6 kg. For the most part though, I got similar results as Zephram Kerman did on his trials. At this point, I think I\'m at the limit of what I can accomplish with MechJeb\'s settings as they are now. If I could some how program various degrees in pitch to correspond to various altitudes, then I could probably engineer more definitive results. But with the slider not having values assigned to its position I feel like I\'m working in the dark. Of course, I could be just missing something as I haven\'t even had MechJeb for a whole day yet. -
Optimal Ascent Profile for this spacecraft
Tarmenius replied to PakledHostage's topic in KSP1 Challenges & Mission ideas
Yes, I tried a couple others. I used the same pitch angles (80, 60, 45, 30, 20), but reached them at different altitudes. I tried 6km, 10km, 15km, 20km, 30km respectively for a more shallow ascent ending up with around 45kg remaining fuel. Then I tried higher altitudes. When I hit them at 13km, 20km, 30km, 35km, I had to leave out the 20deg pitch mark because my Ap had already reached 75km. That produced better results than the shallow ascent, but with 77kg remaining fuel it still wasn\'t as efficient. My next trial will use my original profile with MechJeb along for the Ascent Stats so I can see how much I lose to the various competing forces. I suspect I\'ll lose less turning late than I would fighting atmosphere early, but the real trick will be finding out where each are minimized then aiming for something in the middle to get the best net reduction. If I remember correctly, you and PackledHostage both pitched to 80deg early on and made a slow turn later; is that right? If so, it\'s a profile I\'ll have to try out and see if I can come up with similar results. -
Wow, that\'s some fine work there! I\'ve been wondering how to reliably set up a gravity assist for some time now. I managed to jury-rig the maneuver once, but it was sloppy and I kept thinking 'I wish I knew how I pulled that off.' And now, off to get some use out of the Minmus Rover that I have sitting in the hanger gathering dust! You have my thanks. On a side note: As much as I hate having debris around my own Kerbin, that field of yours looks pretty cool. Kinda reminds me of how Earth looks in Cowboy Bebop.
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Optimal Ascent Profile for this spacecraft
Tarmenius replied to PakledHostage's topic in KSP1 Challenges & Mission ideas
jqhullekes, I was wondering the same thing. I was so curious that I decided to get MechJeb for the first time and try it out. I simply slapped on the case, keeping the stock ASAS since I don\'t know if MechJeb has any mass (1E-05 could mean anything to me), and programmed the Auto Ascent for 75.5km. If any one else is curious as well, here\'s the profile it used: Initial pitch-over to 60deg at 10000m. It held there until about 18000m when it began to pitch again to 50 deg by 20000m. From there it was a steady, incremental series of pitch changes passing 45deg at 23000m, 40deg at 25000m. Then it paused for a moment before a major pitch change to 20deg at 30000m followed by another set of incremental changes to 20deg by 33000m and finally 15deg by 35000m. After that, it coasted to Apoapsis then circularized. When all was said and done, the remaining fuel was 81.8kg. Pretty interesting though jqhullekes and PackledHostage proved that it isn\'t quite the most efficient path. -
Optimal Ascent Profile for this spacecraft
Tarmenius replied to PakledHostage's topic in KSP1 Challenges & Mission ideas
I decided to give this a shot merely as a learning exercise for myself, but was fairly surprised at the result I ended up with. I put the ship in a 75.3km x 77.7km orbit with 81.2kg of fuel remaining (no mech-jeb). I started pitching over to +80deg at about 8000m, hit +45deg around 20000m and +30deg at 30000. At MECO, I was heading at +20deg with an Ap of about 76km, so as I coasted through the rest of upper atmosphere, my Ap settled to the target altitude. Then I circularized as normal, reducing thrust to keep my Ap just in front of the ship. I use this process for almost every rocket I fly, but I never bothered to test how efficient it actually is. Thanks for putting up this challenge, PackledHostage. [Edit]: Second attempt with the same profile yielded almost identical results (go figure). Seems to be a pretty easily repeatable profile in case anyone else wants to use it. -
I finally managed to pull this off while trying to successfully convert my favorite spaceplane from .14. Even managed an unpowered landing on the KCS runway. 8) Immediately after wheels-up, I set my nose to +60deg and held it there until around 15,000m. By 35,000m I was at +30deg and +20 by MECO Only 225m difference between Pe and Ap, without the use of RCS. Just before de-orbit burn, I still had enough fuel to work with in case I undershot KCS On Final Approach and everything looks good. Rolled to a comfortable stop near the end of the runway. Touchdown was somewhere near the middle. It\'s a simple design, but it works well for me.
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Thanks for the support. I\'ve come close to successfully converting the Peregrine, but wasn\'t quite able to achieve orbit. This got to an Ap of 75km with a Pe just below the surface; so with a little more fuel I can get to orbit, assuming it isn\'t too heavy to get off the ground. I\'m going to try adding another fuel tank, and if that doesn\'t work, I\'ll remove the lowest along with the attached wing sections (which would make it about the same size as the original Peregrine). The extra fuel tank worked and I now have an updated Peregrine (Mk15b). It\'s no longer Mun-capable, but once in a 72km orbit, there will be at least half a tank of fuel for maneuvers plus RCS. It also glides just as well as the old version (if not better) and if I launch vertically with a SRB stage, I might be able to manage a Mun trip. Of course, I\'m not the best pilot so others will likely be able to get even more out of it without adding extra stages and whatnot.
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I have updated the Rockets for .15 (and named them 'Mk15' to distinguish them from ones compatible with the demo), but can\'t get an updated version of the Peregrine to work as well as I\'d like so she may need to be scrapped . The rockets are basically the same setup, but I swapped out the winglets for the landing struts. I also removed the extra SAS unit from the Demeter since it is no longer required to prevent fuel being drawn from the Lander. Here\'s some shots of the modified designs: Demeter Mk15 Odin Mk15 Icarus Mk15 Additionally, I am including a slimmed down version of the Demeter called the Anteres 15. It\'s the same Lander, with 7 fewer fuel tanks in the lifting stage. It will still get to the Mun and back, but the fuel margin is (obviously) a bit tighter. Even so, I dumped the final two radial stacks with a little fuel left to avoid space junk, so the margin is still comfortable. Enjoy
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Thanks for checking them out. I don\'t imagine the designs are terribly unique, but KSP isn\'t exactly known for it\'s 'practical' approach to rocketry, except in the case of minimalist designs. ;D So, I figured it might be a good idea to have some less-extreme examples floating around. I\'ve seen a lot of different designs on the boards, so I\'m sure these bear the influence of those who are better at this than I am. The C7 parts definitely make getting to the Mun easier, but it was interesting to descend tail first then flip over at the last minute. At first, I wasn\'t sure the RCS would be enough to the land with. As for the extra SAS unit on the Demeter, I put it there as a spacer to prevent fuel flow through the stack decoupler. First time I took her up, the tanks in the Lander Stage were dry before I realized what was happening. I thought 'Gee, shouldn\'t the first pair of stacks be ready to ditch by now? Oh, crap'
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I\'ve been there a couple of times. The best way I\'ve found is to fly a spaceplane that glides well, set a sub-orbital trajectory ending in the basin and just coast the rest of the way. You\'d only need enough fuel for the initial ascent, which in my experience has been one-and-a-half tanks using the standard-size C7 fuselage (my spaceplane is four tanks long plus cockpit with a delta-wing configuration). Using a stock rocket would follow a similar path, only you\'d overshoot the landing site by a little bit to compensate for atmospheric drag then perform a powered landing. If you\'re at the right basin, it should be visible from the surrounding mountains. If your draw distance prevents a visual from the mountains, simply fly (or fall) toward the center and you should find it. Hope this helps.
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It\'s probably not the biggest or fastest (188m/s at 1500m altitude on an empty fuel load), but it only uses the basic C7 pack. She flies pretty well and is capable of going to the Mun and back. I tried making a much larger version, but it wasn\'t stable on vertical take-off so this\'ll have to do for now. The Peregrine Mk2 VTOL:
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Salutations, good people of KSP! Allow me to present a few tried and true Mun-capable spacecraft. My design philosophy has been to create simple, stable, effective rockets with plenty of fuel margin without being terribly massive. In this, I believe I have been successful. It is my hope that these will provide newer pilots with a forgiving and controllable platform while giving the 'advanced beginner' a design or two to hone their skills with. Constructive criticism from the expert crowd is always welcome, too. Without further ado, let me start with the two rockets compatible with the Demo version (0.13.3): Odin and Icarus Odin is designed around a light Lander and is therefore the smaller overall rocket. I tend to begin a slow pitchover starting at roughly 8000m, aiming to be at 45deg aroung 25000m and 25-30deg by 40000m, maintaining that pitch until desired Apoapsis is achieved. I usually follow this ascent profile for every rocket I fly. Because Odin uses it\'s lifting stage for most of the ascent, it can be a little sluggish to maneuver, putting it behind the Icarus in ease-of-use. Icarus is designed around a larger Lander, but is not that much bigger than Odin and even features an emergency Abort Stage that will get you home from at least Munar orbit. Surprisingly, despite being larger it\'s easier to handle. This is because the main lifting stage is separated around 14000 or 15000m, where pitch is still around 65-70deg. The last of my rockets is only compatible with version 0.14.4 My most recent rocket design, Demeter features a relatively small lander (four half-tanks and two RCS tanks). Incorporating an Asparagus-stalk lifting Stage, it is efficient but can be difficult to handle if not oriented properly during pitchover. In order to prevent space junk, the last radial stacks should be separated before completing the circularization burn (likely with some fuel left). This will leave the central stack for finalizing the orbit, burning to Munar intercept, capture and some or most of the descent (or all if you\'re a better pilot than I am). Finally, I\'d like to present a spaceplane following the same design principles as that of the rockets. Using the standard C7 pack, the Peregrine Mk2 is Mun-capable and glides like a dream at any fuel level. Simply activate the ASAS at +10deg when full and +5deg when empty for best results. With plenty of RCS fuel and thrusters, it is even capable of VTOL with at least one full main-engine tank. I have yet to test VTOL capability under a full fuel load, though I suspect that even when full it is capable of STOL. [Edit]: I should clarify that although it glides well with a full fuel load, I wouldn\'t recommend a landing attempt with more than half. Otherwise, you\'ll have too much forward speed on touchdown for the landing gear to handle. And there you have it, folks. A huge thank you to any who took the time to read this, to Squad for making such a deep yet accessible game, and to the various board users who are the experts at orbital mechanics, maneuvers and rocketry. If I\'ve left anything out, or you have questions, ideas or constructive criticism, feel free to post them. [2nd Edit for minor spelling]
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1) Thanks for that clarification... makes better sense now. 2) I was too early on launch and my target ended up a ways behind. Since there was only 20km difference between orbit altitudes, it seemed like a faster solution to set my Ap at 120km (then set Pe to 98km) to let the target catch up. 3) Thanks for the tip, I\'ll give that method a shot next time.
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Incredible job (as always) Kosmo-not! Just a quick clarification question about your table: Are the white distances for prograde burns and the grey ones for retrograde? I wanted to make sure I was reading that correctly. Also, have you tackled the problems with intercepting a target 'behind' you in orbit? I found myself in that situation earlier today with the target\'s orbit at 100km and mine at 80km. It wasn\'t very difficult adjusting my orbits to arrange an intercept, but because it was all guess-work I doubt my method was as efficient as it could have been. Just raised Ap to 120km for a couple orbits, then raised Pe to 98km for a couple more once the target got relatively close. Once I was less than 10km from the target, I matched orbit velocity but from there my rendezvous was a mess. Overshot, then undershot... eventually I got there, though. Any tips for figuring out which direction to thrust in when closer than 10km but still too far to see whether the target is moving toward or away from you?
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Newt, that would have thrown me for quite the loop. Good thing you already had your Periapsis set! Thanks for the tip, Awaras. I\'ll try those altitudes next time I need to aerobrake. DonLorenzo, that gives me ideas for testing independant tank failures, thanks! Had another incident happen this morning. I was testing a different lander design, with an Emergency/Reentry Stage of only one RCS tank and 8 thrusters attached directly to the Command Capsule. I was showing the game to a friend of mine and was successfully landed on the Mun. He thought it would be funny to reach over and hit the throttle. Not knowing the controls, he hit the spacebar and separated the Lander Stage from the Emergency/Reentry Stage. I botched the ascent, scattering debris all over the side of a mountain. He felt bad, but I quoted Max Grant\'s post above saying 'Don\'t worry, they respawn on the launchpad.'
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ferram: I had a few early rocket designs that were prone to out-of-control spins if I didn\'t pitch over juuuust right (hell, some that spun out if I went anywhere other than straight-up). Took a while to strike that balance between power and controlability. deadshot: Whew. And here I thought it was just an oversight on my part. Damn Xenomorphs *shakes fist*. Anyway, I named it that because it was my first successful design. Stole fire from the gods and all that... In any event, I now design all my rockets with that 2-RCS-tank-14-thrusters emergency stage. And I take screenshots when anything interesting happens... just in case.
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So here I was, about to begin another Mun mission. I\'d been there and back a few times already, but only with the objective of landing and returning safely. For this mission, the goal was to attempt a return from the surface using only the RCS. I knew others had done it, and with successful Mun missions under my belt, I was confident. I never would have guessed what was about to happen. I rolled out my proven Mun rocket, Prometheus. The launch went smoothly and although I could have done a better job establishing my parking orbit, I was still within the rocket\'s considerable fuel margin. The Trans-Munar-Injection burn was the same as it had been the other handful of times I had performed it. And the orbit plane needed no adjustments, so without a Mid-Course-Correction burn, the crew had plenty of time to catch up on their reading. As soon as the Mun\'s Sphere of Influence became the dominant gravitational body, it was time to prepare for capture. I turned retrograde and gave a short burn to set my desired Periapsis then waited for my Lander to reach it. Once at Periapsis, I began the circularization burn. But before I could complete it, the engine shuts off. In a moment of confusion and mild panic, I exited the map and found four full tanks unused and inaccessible. Looking at a still-elliptical orbit, I assessed the situation. Realising I have no way to salvage the mission, I decided to jettison the Lander stage and return home. After a visual inspection of the Lander, the cause of the engine shutoff was clear. I had failed to ensure the fuel lines had been properly connected after re-arranging some parts in the VAB. Left with only the Command Capsule, 2 RCS tanks and 14 thrusters, I needed to finish reducing Apoapsis so that I could plot a more efficient return to Kerbin. This seemed more efficient to me, but I don\'t really know for certain Once I was back in Kerbin\'s Sphere Of Influence, I made my Periapsis at 50,000m to prepare for aerobraking in case I ran out of RCS fuel. Having never before needed to rely on it, 50km sounded like a nice round number just inside the atmosphere where friction wouldn\'t cook my crew but still provide enough drag to eventually bring the Capsule down. When I got to Periapsis, I spent my remaining RCS fuel to bring Apoapsis down to 1,082,300m. And then I waited. And waited. Finally, after 11 orbits of aerobraking, and with a total MET of 1:04:40:00, the crew is returned safely. Good thing they can\'t starve or suffocate (yet). Now, I\'m betting that the astute reader will notice some inconsistencies between the written story and the supplied pictures. Most notably, fuel levels and MET. Sadly, while the original mission was unfolding, I did not have the presence of mind to take screenshots. So, I recreated the scenario. Oddly enough, during the recreation I was much more efficient with my fuel use and had plenty left to deorbit without relying on aerobraking. So I didn\'t rely on it. But the whole situation got me thinking, and this brings me to the true purpose of this post. Has anyone purposefully designed critical system failures to test emergency abort procedures or ensure that the crew could be saved if something horrible went wrong? If so, what scenarios were run and what did you learn from them? Thanks for reading, and I look forward to hearing about your scenarios so I can test them myself