Tarmenius

PakledHostage, I\'d definitely say that counts. Have you tried landing the Low-Fuel Lander yet? My next goal is to take what I learned from my tests and try that one again. closette, don\'t count yourself out just yet. Now that landings no longer have to factor in the Leaderboards, I\'d say it\'s anyone\'s game. Having made several attempts at a 3x3km orbit, often times botching it terribly, I realize how slim the margin of error is. Incidentally, the best way I found to pull it off is to start circularizing a good 30 seconds before reaching Pe, pitching above the horizon slightly if needed. You\'ll end up having to separate the process into a few short burns to keep Pe from running away from you near the end, though. That\'s how I finally narrowed down the 2900 x 3050 orbit. Either way, I think a tolerance of +/- 1km is reasonable, for as difficult as such a low orbit is to achieve. And if someone is really having a hard time making it, I\'m not against making exceptions either. I really want this to be more of a challenge and less of a competition. And given the nature of this forum\'s members I\'d wager almost everyone would be okay with that.

Good job. Flying through that gorge is quite the experience. I\'m never fully sure I\'ll get out of it in one piece...

Vanamonde, I jumped a cart off the cliff behind you in the middle screenshot. Lots of fun! I saw the cliff from orbit, landed at the bottom and drove my way up. I took a picture of the slope as I went. When I jumped, I wasn\'t going as fast as I would have liked and was so focused on not destroying myself on the way down that I only got a screenshot after the first bounce. I ended up surviving, too.

Thanks. I changed to original post to show the new goal, but kept your positions on the Leaderboards until we get new results. Now, I\'m off to get some screenshots that reflect the new goal as well.

Yes, I did. Thank you for pointing that out; it\'s been corrected. So, thinking on the suggestion PakledHostage made, it has prompted me to want a change in the parameters of this challenge, as much as I\'d hate to do it after it\'s been started. I just realized that the way it\'s set up currently does not isolate the Insertion phase. Instead of judging by fuel remaining at landing, I think it would work better to establish a standard orbit altitude and determine who can reach it on the least amount of fuel. Since closette and Kosmo-not have already submitted entries under the current rules, I\'d like their input on whether to make the change at all. And I\'d like input from everyone on what altitude the standard orbit should be. Personally, I like the 3km x 3km. Now, on to some more test results. First, I expanded on my original set from a couple posts back to include establishing a 3km x 3km orbit. Again, I performed the initial burns from just inside the Mun\'s SOI (both at roughly 2,087,000m). Here are the results: [li]Burning Kerbinward, I set my Pe to 2950m using 21.9kg (again). Pe changed to 3310 by the time I got there (?), with an orbital velocity of 852 m/s (again). Setting my orbit to 2900m x 3050m used 40.7kg, with a total fuel consumed of 62.6kg (187.4 remaining)[/li] [li]Burning Retrograde, I set my Pe to 3030m using 41.6kg. Pe changed to 3050, with an orbital velocity of 783.3 m/s. Setting my orbit to 2820m x 2730m used 30.1kg, with a total fuel consumed of 71.7kg (178.3 remaining)[/li] Next I performed the same maneuvers (kerbinward/retrograde) from the scenario\'s starting point. Here are those results: [li]Burning Kerbinward, I set my Pe to 2700m (Projected by Patched Conics) using 5.0kg. Pe changed to impact by the time I entered the Mun\'s SOI so I adjusted it back (burning directly away from Kerbin) to 3800, using 0.2kg. By Pe, I had an orbital velocity of 852 m/s (again). Game froze at that point, but given the identical velocity I assumed the same fuel use from above (40.7kg). Total fuel consumed: 45.9kg (204.1 remaining)[/li] [li]Burning Retrograde, I set my Pe to 2500m (Projected by Patched Conics) using 4.6kg. Pe changed to 1200m once inside the Mun\'s SOI so I adjusted it back to 3010m (burning Prograde), using 0.3kg. By Pe, I had an orbital velocity of 859 m/s. Setting my orbit to 2750m x 2940m used 42.5kg, with a total fuel consumed of 47.4kg (202.6 remaining)[/li] Hopefully that\'s clear enough. If not, I\'ll ask some people I know if they have a spreadsheet program I can use. In summary, burning toward Kerbin proved to be more efficient and even more so from the scenario\'s starting point. I\'m sure Kosmo-not already knew that, though

Good suggestions. I particularly like the idea of a 3km x 3km orbit; it takes the landing variable out of the equation. I\'ll go run a couple more tests right now.

After a couple tests with the Standard Lander to measure the differences between burning toward Kerbin and burning Retrograde, here\'s what I found (both burns were initiated just inside the Mun\'s SOI): While burning toward Kerbin, I set my Pe to 2994m (aiming for 3000). This used 21.9kg and resulted in an orbital velocity at Pe of 852.3 m/s. While burning Retrograde, I set my Pe to 3038 (again aiming for 3000). This used 40.5kg and resulted in an orbital velocity at Pe of 784.6 m/s. Interestingly the Pe\'s were about equal distances from the terminator, with the Kerbinward on the night side and the Prograde on the day side. Sadly, my poor descent control didn\'t allow further comparison of fuel use.

You\'re welcome. Out of curiosity, once inside the Mun\'s SOI, have you found it more efficient to burn toward Kerbin instead of strictly retrograde? Also, if your orbit is 10km by 5km where your Pe falls just on the night side of the terminator, I imagine there wouldn\'t be much difference in velocity or altitude if you were to wait until the day side to begin your descent. I\'ll have to try it to be sure, though. Congrats on getting around the no-right-clicking-on-Macs issue!

Congratulations! *Throws confetti* RCS can be a life-saver during that last bit of descent. I always bring some with me, just in case.

Toward the end of your descent, when you\'re too close to the ground to risk turning 'sideways', you may want to consider only pitching slightly away from your horizontal direction of travel. Even though the retrograde marker moves significantly away from vertical, your actual horizintal velocity is likely to be pretty small. By pitching over slightly, you will slowly bleed off the little that remains while still keeping control of your descent rate. Plus you won\'t have to turn much to get back to a completely vertical landing position when the time comes. Hope that made sense and it helps

By all means, feel free to reclaim it. Feel free to try it without MechJeb, too! And if anyone can manage a return trip to Kerbin, I will definitely think of the most epic medal I can and award it to them. Hell, for such an incredible feat I may have to mess around with MS Paint and create an actual image of the medal, too. [EDIT]: Although it wasn\'t a better result than my previous attempt, while landing the Standard version I did manage a nice view of the Mun Arch.

Thanks Zephram, that\'s exactly the purpose I had in mind when I made the last one. Since it grew into this one, I\'m thinking I may compile the results from these two plus Optimal Ascent (With PakledHostage\'s assent ) into one comprehensive picture of the most efficient Mun mission. [EDIT]: After a couple more attempts with the Low-Fuel Lander, I still can\'t manage to land with any fuel left. I\'m very close though. The most recent attempt got me to the surface with only the engine destroyed after again running out of fuel meters above the ground. I\'ve tried two methods: drop Pe to 2500m upon entering the Mun\'s SOI to descend from there, and establish a 10km orbit before dropping Pe a little below the surface, giving me a long path at very low altitude so I could find a good landing site. I think next time I\'ll establish a 10km orbit, then drop Pe to 2500m (saving a little fuel) and land as usual. Hopefully the little fuel I save will make the difference in allowing me to land safely.

The new challenge is up (http://kerbalspaceprogram.com/forum/index.php?topic=15844.0), but I will still be monitoring (and probably attempting) this one. So if someone reading this is new to the challenge, you are still encouraged to participate. As I said in the original post, landing site and pilot skill are still a factor in the results.

Thanks guys. PakledHostage, I know how that goes. A few years back, I was working for a small manufacturing company doing very repetitive tasks (operating press-brakes, assembling parts, etc), and while some of my co-workers saw the repitition as a drawback, it allowed me to think about and come up with some cool stuff. Without letting it distract me, of course. Anyways, no hurry on getting to this; I don\'t plan on going anywhere closette, the Low-Fuel Lander is basically the same craft, substituting the FL-T250 half-tank for the Mk1 Fuselage. This design won\'t work when jet fuel is separated from rocket fuel, though. So when that happens, hopefully we\'ll have better options for creating this type of scenario. And while the fuel budget is tight, it should be doable for you. You only used 108 kgs of fuel in the last challenge, and the Low-Fuel Lander has a capacity of 150. I botched my own attempt, but I\'ll get it. And so can you... if you want to.

Having narrowed down the most efficient Munar descent from a specific orbit in my previous challenge http://kerbalspaceprogram.com/forum/index.php?topic=15407.0, the natural evolution of the topic drew conversation toward what effect the Munar Insertion has on overall efficiency. Thus, a new challenge is born. Here, we will focus primarily on the various methods of transitioning from Munar Intercept to Descent. Is it more efficient to go directly into the descent phase after entering the Mun\'s Sphere of Influence (SOI)? Or perhaps it will save more fuel to set up a bi-elliptic transfer into a low-Mun orbit before beginning your descent. There are plenty of options to explore, but only one will prove to be Optimal. I\'m sure some of you have done the math, and that\'s wonderful for theory but let\'s see how it works in practice. As always, be encouraged to discuss that math (even though I won\'t understand most of it ), and any theories you may have for saving those precious fuel units. Even though this is framed as a challenge, the true goal is a greater understanding about how to get the most from our rockets. With that, we come to the substance of our challenge. The goal will be to insert into a 3km by 3km orbit around the Mun. Success will be measured by how little fuel is used during this phase. To create the scenario, I have taken the original stock lander from the Optimal Descent (to theMun) challenge and placed it on a free-return trajectory through the Mun\'s SOI with a Pe of just under 1 million meters. This was chosen to allow a subsequent return to Kerbin with a Pe of roughly 30,000m (a safe re-entry altitude) and thus simulate a more realistic flight plan. You begin the challenge at the not-quite-half-way point, right after I had performed the Mid-Course Correction1 burn with fuel leftover from the Trans-Munar Injection stage. As with the previous challenge, the lander must be activated with [spacebar] as my proof to you that the lander starts with 100% fuel. For those of you who did not participate in Optimal Descent, and are unfamiliar with how to use the attached persistance files, a brief explaination: Simply move your existing persistance file (found in the 'KSP/saves/default' folder) to another location for easy recovery, download mine and place it where yours was. Upon starting the challenge, you are free to use whatever method you desire to reach the designated orbit. You may also land if you choose, to demonstrate the cumulative effect of your Insertion, but that is entirely optional. However, there will likely be Medals for certain extraordinary achievements. Positions on the Leaderboards will be determined by screenshot of fuel remaining (in kgs... Gubs, while amusing, just didn\'t feel right after the initial laugh was over). I chose the MCC1 location as the starting point to allow the widest variety of maneuvers while still focusing on a single aspect of the mission, so don\'t be afraid to think outside the box. And for those of you wanting an extra level of difficulty, I have also included a lander with as little fuel as possible using stock parts. It is the second persistent.sfs file attached. I tried to create an identical free-retun trajectory for this lander and while it isn\'t perfect, it\'s pretty close (~34,000m higher from a target of 1Mil m). Be warned, it has a very tight fuel margin. And good luck getting back to Kerbin with that one! Mwahahaha! Seriously though, I barely made it to the surface. I would have made it in one piece too, but I ran out of fuel a few meters up and was going about 5-6 m/s when I landed but was bounced tens of meters back up. I just managed to right myself and save the capsule, so at least the crew made it alive, even if the rocket isn\'t intact and the tank is empty. [NOTE]: I have made changes to the challenge\'s goal. This should now allow us to focus entirely on the Insertion phase. Leaderboard positions will be updated when new results are submitted. Once again, Glory and Honor are there for the taking! Who will ultimately prove themself worthy of the top spot? Will it be you? Standard Lander 1. PakledHostage: 202.9kg 2. Kosmo-not: 202.8kg 2. closette: 202.8kg 3. Tarmenius: 202.6kg 4. togfox: 201.1kg Low-Fuel Lander 1. closette: 99.8kg 2. Tarmenius: 86.2kg Landed *In order of submission and unranked as it\'s optional* Kosmo-not: 11.6kg (Low-Fuel Lander) / 109.4 (Standard) closette: 111.9 (Standard) REMINDER: The first attachment is the Standard Lander. Second is the Low-Fuel Lander

I was thinking it would be best as a separate-but-related challenge, too. And if I were to set it up with the craft outside the Mun\'s SOI, it would definitely be on a path to take it inside. I was contemplating on just how far inside the Mun\'s SOI to make it, until you mentioned a free-return. That would definitely be both a realistic scenario and a good middle-gound between the possible TMI options. Although my ideas for a new, low-delta-v lander (inspired by PakledHostage\'s post) would require parts not found in the demo, I\'d like it to be accessible to as many players as possible. So maybe I\'ll have two versions... This\'ll be fun to set up. [EDIT]: I just checked the Demo and this challenge wasn\'t compatible with it, so the next one won\'t be either. Of course, this just means that anyone who wants to participate will have to upgrade, as if they needed a reason beyond KSP\'s full greatness. By the way, thanks for the suggestions and the compliment. I was a little unsure of myself when I set the whole thing up, so it\'s nice to hear I did alright.

Well I managed to fly through that gorge, but I overshot the peaks a little bit. Even so, with the slight plane change maneuvers and correcting my Pe (I dropped it too low at first), I still managed to retain 134.9 Gubs. Not good enough to advance my position on the Leaderboards, but still a decent result all things considered. PakledHostage, we may not need to wait for docking to have a lander with such a tight fuel budget. I\'ve got a couple design ideas I\'ll mess around with and if I come up with something workable, I\'ll let you guys know. closette, my gut reaction is that your first option may be more efficient since you\'d be moving slower during the initial burn, maximizing the effects of your thrust. Of course, I don\'t know for sure because in that case, you\'d have a slightly higher velocity once you reached the 10km Pe. I guess it depends on the net difference between the two. And now I really want to expand this scenario to include the insertion. Would you guys use it if I made a new persistent.sfs with the same lander, but just outside the Mun\'s SOI? Or should it be more toward halfway between Kerbin and the Mun?

Excellent point. I\'ll be sure to make it clear that this method is only the most efficeint from an already-established Munar orbit and that through proper insertion planning, better results can certainly be achieved. You\'ve also given me an idea to expand this challenge to begin just before entering the Mun\'s SOI so we can factor in the insertion as well. Although perhaps that would be better served in a new-but-related challenge... [EDIT] The original post has been updated. Please let me know if there are inaccuracies or if it\'s difficult to follow.

We\'ve all done pretty damn well in my book. The difference between 1st and 10th is only 12.7 kg/Gubs which really isn\'t very much. Plus, you managed a night-time Munar landing without using MechJeb. No small feat from where I sit. And I looked through the paper you attached. If I could understand a tenth of what they were saying, I\'m sure I\'d find it very helpful indeed. It will take a mind way more mathmatically competent than mine to make full use of it It did give me some ideas about how to better incoporate plane changes into the typical Hohmann transfer, though. After a couple tries with the bi-elliptic method, I managed to use less fuel than the 'direct descent' method, but still 20-30 kg/Gubs more than the one we\'re already using. So I think it\'s safe to say that the most efficient method is to drop your Pe as low as you dare then kill horizontal velocity, turning the craft to vertical slowly while throttling back a bit to perform a 'reverse gravity turn' just before touchdown. If that sounds right to everyone, I\'ll add it to the bottom of the original post so that passersby can benefit from what we\'ve learned here. Of course, anyone who wants to can still try for a top spot on the Leaderboards and I\'m certainly not giving up on the mountaintop landing goal.

BlazingAngel665, that is definitely an interesting idea. I\'ll be trying it out shortly. And Zephram, if I remember correctly it is indeed a bi-elliptic transfer. Also, I tried your 'wacky idea' a couple days ago, but I was so busy enjoying the scenery that I didn\'t brake in time. Poor Kerbals... Sounds like I\'ll have to give it another go.

Excellent work, mager42! And even managed to get them back to Kerbin. Very impressive.

I imagine there will be a great number of changes when 0.16 comes out. I\'m really looking forward to seeing how it affects this and the Optimal Ascent challenge. I finally managed a mountain landing, though I had a little too much altitude when I began the final descent maneuver and ended up using too much fuel. Coincidentally, it was near where JellyCubes marked the 2.7km peak.

My first time aerobraking, I was returning from the Mun and I also set my initial Pe to 50,000m. But even after using my remaining fuel to reduce Ap to 1.1 million meters, it took another 10 orbits to finally reach the surface of Kerbin. It was days of simulated time. Since then, I have found that it is much faster to set Pe to just under 30,000m. Even starting from the Mun\'s altitude and using the full lander, the crew experienced only slightly more than 2 G\'s of deceleration. This should be well under any heat generation limits added in the future. As an added bonus, no additional orbits were necessary to reach the surface. If you wanted to return to Kerbin orbit rather than the surface, make your initial Pe closer to 35,000m and that should do the trick.

Good job guys. I\'ve updated the Leaderboard. I liked the idea to rename fuel units, but as Apotheosist mentioned, 'ish' might cause some confusion over the accuracy of our numbers. So, after some searching I decided to (tentatively) rename them 'Gubs.' It\'s a shortened version of 'Gubbins' which means 'an object of no value.' I thought it was fitting. If someone has something better, feel free to post it. I\'ve been trying to stick a mountaintop landing, but mostly I end up cartwheeling off into the distance. I\'d set it up so that my reverse gravity turn ends just above the peak, but in practice it\'s quite difficult. I either add more craters to the Mun, or use too much fuel during vertival descent. I\'m determined to pull it off at least once, though!

That\'s pretty awesome. Now I have an urge to watch an internet-cafe full of people play KSP with horribly (or awesomely) Kerbal rockets! Tosh\'s FPS Pod plugin is what will give you a display of your current actual altitude. You can find it here: http://kerbalspaceprogram.com/forum/index.php?topic=11214.0 closette: A Masters thesis devoted entirely to a Lunar descent? Wow. How awesome is this game that lets us so casually accomplish what so many brilliant minds devoted so much energy toward. Now, I\'m off to try landing on a Munar mountaintop...