codepoet

I have finished my own entry. The boys did not make it back to the pad, so not really meeting challenge, but since I could use the work I did on mechjeb for this challenge to drop it straight into the launch pad from orbit, I do not want to be accused of showing off! I also rather prefer the ending this way too... I did score bonuses for a fairing, scanning Laythe and leaving a working refinary on Laythe.

You are always welcome to fork the code in Github and then you can make whatever modifications to the functionality that you like.

Rokker has confirmed that this now works with 0.23

Sorry for the bad support - I have only just realised that you have posted this. Yes, you are correct, it only starts moving fuel around once the stage that it is in has become active (more specificly it depends how far up the stack you attach the unit). I have not really given this aspect of it much thought - I just wrote it to do what I needed it for. However I would welcome feed back from other users - would it be better if this aspect of its functionality was developped somehow, and if so how do you suggest I make it work?

Great stuff - yes do promote the challenge, it would be good to get some more competition on the leaderboard. I will have my own entry in soon. Having done that I might even take a look at your Eve challenge (I have never been to Eve). Thanks for entring into the spirit for things

Hillarious! I really enjoyed reading that. Unforuntaely you missed out on the 2t bonus for leaving a working kethane refinary on the surface as Jeb forgot to unplug it before lift off, however I suppose that means that you win the 2t bonus for leaving it on orbit instead. You definately get the 0.1t discresionary bonus for making me laugh, so that means you come in with a score of 79.93t - well done, you are top of the leaderboard.

I am sorry that the patch was not working as well as it needs to, and that you have spent time having to play around with it. I wrote the stuff I did for my own use, and offer it to the community without vanity - obviously everyone needs code that they can rely on so there is no need to appologise for rolling it back. Personally I see coding mods a part of playing the game and this all arose from my own game play. I will send some email for clarification about what the issues were.

For the kethane refinary to work there needs to be a fuel tank adjacent to the converter unit. On my rig I used a tiny torus shaped one on top of the converter. In KAS the winch needs to be "docked" to be able to transfer fuel through it. Once it is connected you can transfer fuel from the fueld tank next to the converter unit into any other tanks.

I made heavy use of mechjeb, but at least the craft was stock parts apart from mechjeb and the KAS attachments. I think I qualified for the bonus "Leaving operational kethane refinery on surface of Laythe: 2t bonus", but thats all. Craft was not really optimized (1300m/s delta-v left when in low orbit around Laythe), so I guess with some work it might be possible to get the same mining rover there with a <100t launcher of similar design (Wait for better launch window, reduce surplus delta-v, empty fuel tank in rover). The mission was a nice challenge for me. Good effort. You are top of the leaderboard witha score of 145.22t How did you get use of mechjeb for the return journey? Also did you have any problems caused by the dodgy RCS on the stranded craft? I am glad you enjoyed the challenge - so goo I hear that you did it twice!

Oh I see!. Sorry, that must have been frustrating. I will update the challenge description so others don't have that problem. I am looking forward to seeing the pictures. I have just put up the images of my landing. Still have to get home now...

Is that your submission chlue? What was you mass at launch? Did you make it back to KSP pad? Did you get any of the bonuses? How did you do it?

Sing it brother - you are preaching to the choir!

This could be to do with changes in the parachute targeting patch that was pulled in #128. In order to increase the precision of the simulation the simulation's time step is now variable, depending on how long it takes, (with a view to being able to do at least 5 simulations per second) If you have a fast computer then you will get a shorter timestep (and hence a more accurate simulation) and as you get closer to landing the simulation comes to an end sooner, and so takes less time and so becomes more accurate. However, now I think about it, the simulation times out after a certain number of time steps, so if your computer is fast, and the timestep is small then it could time out before the simulation lands / aerobreak completes. I did my development on a rubbish old laptop as I do not have lots of money for a swankie fast machine, so I have not been able to test that situation. If it is all my fault - sorry guys

I think it would be best to create a new "final decent with parachutes open" landing step, in order to get it to not try to to course correct once the chutes are open as it is imposible to control attitude from there on in. I am not sure if I will get time to do more work in this soon, but let me know if you are on it so we do not duplicate effort.

How are you getting on with your mission? I am in low orbit around Laythe now, just planning the landing manover. What is the best way of making videos of KSP? If I pull it off no-one will believe me without a video!

Sounds like a nuke to me - does the description suggest it is a nuke? There is nothing in real space with ISP more than 450ish (SSME?) other than ions, so 800 sounds a bit fanciful.

I have never used it, so I can't comment - perhaps others have a niew, but if you think it is balanced then I guess it is. I have used KW, which to be honest I think is not really balanced - if it was then it would not always come out as the most efficent choice! But as long as you are not using some new uber-physics engine that has 1000ISP 2000thrust and weights 0.5t then I guess that is fine. In the rules I said no nukes, but yes to ions as ions exist in space for real*, where are as nukes don't (I know that there are real world designs), so if mods reflect technologies things that exist in the real world then that is fair play. *ions are also hard to use for interplanetary burns, so there is a genuine trade off of loosing the oberth effect. This tension is less so with nukes.

YEs, but that is what Mechjeb is for - doing a series of rather dull burns while I live RealLife... Yes, one of those tiny torus shaped tanks. It holds enough fuel for about 90m/s for a correction burn during the landing high in the atmosphere, and then for the final breaking before landing. The rest of the landing will have to be targeted with the ion drive (which is super hard because it takes a long time to lower the Pe, and the wholelanding has to be done in sunlight. I plan to land within 20m of the hapless trio. I have spent the last 2 weeks writing code for mechjeb to get it to be able to open parachutes at a variable height to be able to target parachute landings more precisely. I figure that it is not really cheating if you have written the code yourself. Under the kethane tank, and above the rockomax that will become visible when the ion stage detaches before landing. If I am lucky I hope to raise the PE of the ion stage to stop it burning up, and then use it to scan the whole of laythe. If I was really cleaver I would use it to provide some delta-v back to kerbin (and machjeb too) but I have not bothered and will fly home by hand, which will make landing on the pad harder.

Good effort. Obviously there are a few requirements not met - such as getting back to the pad. Also for clarification - the requirement that they come back enclosed, also includes the ascent. However having them sitting on the top of a rapidly emptying tank sure is fun! You have also set a benchmark for 299t for a straight rescue - you are top of the leaderboard ... for now!

I have been doing aload of work on interplanetary burs with ion engines. My approach is like yours - an ecentric parking orbit, built up over several orbits, and then I adjust the Ap to be able to time a mun slingshot, to get a bit of extra delta-v to compensate for not being able to do the full interplanetary burn at 72km. As I pass the mun, I burn away and raise the AP up to Jool or wherever. Often I will raise it most of the way, but wait until I have left the kerbin SOI, and then finish the job at the exact moment of transfer window to get an optimum transfer.

1. You will have to scan to find out where the nearest kethane is, however the preamble for the challenge might offer some clues. 2. It is only a small bonus, the idea is to encourage some getting some sort of infrustucture set up, as well as the rescue, but I did not want to provide too string a stear towards any particular solution. 3. Sure - send a rover (but the rover mass will count towards you launch mass), or have them walk. I am keen to encourage precision in this challenge (hence the island location), so I said get back to the pad, to get folks thinking through the landing rather than just hammering straight into kerbin from interplanetary. Obviously you win the internet if you get them to land on the pad.

Laythe rescue challenge Download the game save for this mission from here: Kethane is available from here: KAS is available from here: Bob, Bill and Jeb have been at it again - this time getting themselves stranded on the outer edges of the Kerbol system. Everything was going well until they landed on a small island on Laythe, and while Bill and Bob went out for a walk down to the beach, Jeb wanted to check out what the "Vent Fuel" button did. Now they do not have any fuel to launch themselves back into orbit and get home. As the Director of the Kerbol Space Programme, it is you task to get them back home to Kerbin, within the launch and budget constraints imposed by constant cuts to the programme's budget which means that the rescue mission needs to be as small a package as possible. There are a few other things that might need to be taken into acount as you plan the rescue: Although the crew on Laythe have started blaming Jeb for venting the fuel to the atmosphere, Jeb tried to deflect criticism by drawing attention to the work that Bob did on designing the ship's RCS system. Some of the technicians have been murmuring that he is in fact correct and there is a design problem, which is remarkable for Jeb. A software error resulted in the return fuel package that was to be left in Laythe orbit, has in fact been put into the wrong orbit with a midrange inclination rather than the intended equatorial orbit. Bill confessed that he had made some changes to the software for the orbit capture burn, because "he likes hacking around with web pages at the weekend." All three of the crew have reported that there is a strong smell of kethane in the air, but after the best part of a year in space Jeb is dying for a smoke, and CapCom are doing all they can to persuade him that it might not be safe to light up. The recently signed atomic treaty means that the nuclear rocket industry has closed down, and so no nuclear forms of propulsion are available. Rationale The rationale behind the is challenge was to find out how efficiently in terms of launch mass it is possible to establish a kethane operation on Laythe. It might be easier to just send them the fuel they require or a de-orbit the fuel that is in orbit around Laythe, but it is anticipated that a kethane operation of some sort will be the best solution. There might be other solutions such as mining for kethane on a different moon in the Jool system - I await your creativity.The challenge will also test: an efficient launch to LKO an efficient transfer to the Jool system the ability to land precisely on Laythe without needing a large fuel/parachute mass the ability to plan effective slingshots out of Kerbin, to Jool, up through the Jool moons to save as much delta-v as possible. Basic Requirement To qualify as an entry, get Bill, Bob and Jeb back to the KSP launch pad - a picture of them standing on the top of it will suffice along with pictures / video and description of how you did it. Rules You are allowed only a single launch from KSC. You can use mods as long as they are "balanced". It is anticipated that you will use kethane, and it is required that you use KAS as a KAS connection (for a winch not fuelpipe) is already installed on the ship stranded at Laythe. Please identify the mods that you use. No cheating - hyperedit, infinite fuel etc. The crew must be enclosed for the ride home (including the ascent from Laythe) - don't make them do the whole trip in an external seat, (although it you manage to do this with a record score, let us know anyway for an honourable mention) No nuclear engines. Entries that use mechjeb are acceptable, and will be scored separately, however be aware that mechjeb is not installed stranded craft. No adding MJ to existing pods - if you want it you will have to somehow attach it to the craft you are flying. Scoring Your score is based on the launch mass for your rescue package. Obviously the lowest score wins. Some bonuses are available: Scanning the whole of Laythe for kethane deposits: 1t bonus Leaving operational kethane refinery on surface of Laythe: 2t bonus Leaving operational kethane refinery in Laythe orbit - 2t bonus Coming up with something interesting / entertaining for Bob, Bill and Jab to do on Laythe while the await rescue - up to 0.1t bonus at my discretion Having your rescue payload enclosed in a fairing for launch from Kerbin until atmospheric drag < 1m/s2 - 2t bonus Ranking (no mechjeb) 1. 2. 3. 4. 5. Ranking: (with mechjeb) 1. codepoet - 32.1t (Bonus for leaving kethane refinary in orbit, scanning the whole of laythe for kethane, and using a fairing for the booster. Did not make it back tot he pad ) 2. Ziv - 79.93t (Bonus for leaving kethane refinary in orbit, and the boys having some fun on laythe) 3. chlue - 145.22t (Bonus for leaving working kethane plant on Laythe) 4. Ziv - 299t (did not make it back to the pad) 5. My entry I have been researching my entry and have all the various parts cracked. I am just playing it through now and will post pictures as I go: Putting the fairing on in the VAB before rollout... Liftoff. I am useing KW rocketry, and procedural fairings. Loosing the solids. I am sure that I could have made my launch mass smaller but using a liquid first stage, but the rocket looks pretty this way Loosing the fairings First look at the spacecraft. You will see that it is asymetrical - with a kethane drill on one side, and lots of tanks, solar panels and hardware on the other to keep the CoM in the right place. Upper stage releases the craft. The craft performing a series of burns to raise the apoapsis on the dark side of kerbin, in the direction that will be directly oposite the sun at the moment of the Jool transfer window A closer look at the craft. A pretty picture of an eclipse... After a series of burns the apoapsis has been raised to just short of the Mun's SOI, and we have got 5 days to go until the transfer window.... After waiting for the right moment, raising the Ap to slingshot around the Mun on the dark side of Kerbin to get thrown out of kerbin SOI in the helio-prograde direction. Tweaking the munar Pe to get the most out of the flyby. Approaching the Mun SOI... Turning on the kethane scanner to survey a small part of the Mun as we go by. You never know when it might be useful... Flying by the Mun with AGL < 1km! After the flyby we have managed to get out of the kerbin SOI, and raise our helio apoapsis to 17m km from 13m km. Time to plan the main transfer burn - 2100ish m/s will take around 6 hours, but then that is only an hour and a half on 4x phyics warp, and I can watch a movie while it happens. Goodbye kerbin... After the interplanetary burn to raise the helio apoapsis to over 70m km we have got an encount with Jool, but because our inclination is not matched with Jool, we are passing underneath it. Not a problem, we can match plans at the decending node, which happily is quite a way out so that will save us some delta-v After the plane matching burn we are passing withing sight of the moons of Jool. Time for one more burn to place the trajectory into the joolian atmosphere for an aerocapture. On approaching Jool, there is time for tiny adustments to the Pe to ensure that we get a safe aerocapture, that will still leave a high Ap so we can match planes with laythe cheaply. Mechjeb's re-entry simulation does the hard work for predicting the aerocapture. Time to pull the solar panels in - don't want the to get burned. Wow! That is hot. Good job I stowed the panels. Now we are a highly ecentric orbit around Jool. Time for a couple of burns to plane match Laythe, and also to tweak the Pe for an aerobrake manuover. Back in the oven! Good work mission control! We are in an stable orbit around Jool rising to just beyond Laythe's orbit. It should be just a matter of time until we get an encounter, and we do not need to worry about bumping into any of the other moons either. A quick burn to adjust the encounter when it came. The burn was just in time too as the sun set behind Jool A first taste of the air on Laythe. Aerocapture! Planning the landing: The landing site is at 3,15'S so first we are adjusting the inclination of the orbit to be 176.75 so that we reach the southern most part of the orbit just as we have passed across the sunny side of the planet. This way the whole of the approach to the landing site will be in sunlight. We will have to wait for the landing site to rotate round to that position though. In the meantime we can perform a series of aerobreaks to circularise the orbit. With the orbit at about 70x70 the Pe has then been lowered to just over 55km (the top ofthe atmosphere) at the southern most part of the orbit. Now the landing site has rotated around into position it is time to start the landing. First step is to lower the Pe to 40km. Because I am using ions to do this I do not have spare capacity in terms of time to allow mechjeb to have a stab at it. In particular MJ wants tto drop the Pe to -10% below ASL for the deorbit burn. We are going to do a much shallower landing approach, and across a full half orbit. MJ will typically usea quarter orbit for landing approach. Having set the Pe to 40km, the ion propulsion is staged. This has an octocore in it, so it can serve as a kethane scanning probe, if only I am able to stop it burning up in the atmosphere. Time for a rapid about face, and a burn to raise the Pe as fast as possible. Unfortunately because it only has two smaller solar panels and Jool is so far out there is only enough electrical power to run the engine at ~10%. However the craft is only about 10% the mass of the craft that we bought over from kerbin. It is a close thing, but eventually the Pe raises to about 50km which is high enough to not burn up. Having saved the ion probe from a firey death, we need to land the refinary. As we enter the high atmosphere as few manual burns move the predicted landign site into position. Limiting the throttle to 1% allows for much greater precision. Here we are within 50m ot the target. Mechjeb could do this for us, however if I were to turn it on it would first try to do a deorbit burn as the Pe is still >0. I considered making a code change to mechjeb to fly this manuover for me, but in the end just did it my hand. (I guess the change to mechjeb would be to not bother with a deorbit burn it there is already a predicted landing site.) Note that we are not using the little rockomax engine, and have 92m/s of delta-v to play with, as we are only carrying 10 units of liquid fuel. Precision is the name of the game here! I realised that I had now enabled parachute deployment in the autopilot. Turning it on means that the landing position moves and so calls for a further adjustment. I then shut down the engine to stop MJ trying to "help". Here you can see the two orbits of the lander and the probe pasing overhead. Now that the atmospheric drag is more than 1m/s2 mechjeb decides that it can not control the attitude of the craft, and to switches to a mode of controlling the landing position by adjusting the height that the parachutes are deployed. Notice the "multiplier" at the bottom of the landing guidence screen witch is the number of times above the full deployment height that the parachutes will be semi deployed. At this point it has got the prediced landing point down to within 8m of the target. First glimpse of the island we are hoping to land on. As we approach the landing site the parachutes are about to be deployed. Out goes the drogue! With the drogue fully deployed it looks as if we will land around 50m from the target. Don't ask me where I got the parachute from - it looks like Jeb designed it. Down she goes. Out comes the main chute. About 20m from the surface the drogue is cut as it is holding us off balance, and the engine turned back on for a braking burn. Safely down, 51m from the target. A welcome sight for Jeb and his friends, and just in time too, they were down to their last can of space-spam. Hopefully the mission planners remembered to pack some beers for the return journey. Give that hose another tug I am sure it is long enough! I knew the plug would fit. Fueling her up. After putting the boys back into the lander, we target the fuel in orbit and wait until laythe has rotated so we can launch directly into its plane for a rendevous. We might well need every ounce of fuel to get there. Lift off - it feels great to be back in the air and on our way home. Jeb, you did remeber to stow those experiments didn't you? Chasing down the fuel package and planning the rendevous by hand. Refueling in sight... Final approach - the RCS was not much use but by carefully cancelling out the relative velocity before the final approach it is not much of a problem. Got you - now lets fuel up for the journey home. Meanwhile, in an eqitorial orbit nearby the kethane scanning probe that was released during the refinary's landing is busy raising its apoapsis. THe lack of sunlight means that it has its thrust limited to 13%. After several burns at the periapsis,the apoapsis has been raised to around 3000km which i right on the edge of Laythe's SOI. At this point the orbital velocity is around 500m/s rather than 1800m/s for a low orbit, making it much cheaper to change our inclination to 90 degrees. We do this across several orbits making burns at the apoapsis. The manouver is slightly complicated by having to be in sunlight when it is made. Before you know it we are in polar orbit,and ready to aerobrake the Ap back down to scanning range. Pulling in the solar panels in advance of the aerobrake. This requires careful planning because if the 15 units of electricity in the octocore run out before the aerobrake is complete then there will be no power to redeploy the panels. Circular orbit at last. A few days later... Meanwhile the return crew are coming up on the ascending node, so it is time for a burn to plane match kerbin, and make a few adjestments to ensure an encounter. ... and later another burn to turn it into a close encounter. Once in the kerbin SOI, a burn lines us up for an aerocapture, and then some small tweaks with the RCS allows us to adjust the altitudenof the aerocapture. OUCH! Good work boys - a nice orbit to guide into KSC from... What was that Jeb? You want to fly the landing manually? I am not sure that is such a good idea.... "Jeb - listen to mission control, they have had over a year to do the maths on this one...." "We are going to overshoot - pop the chutes Jeb" What was that loud bang? It sounded like one of the parachutes being ripped off... "Well this another fine mess you have got us into Jeb. We are back where we started - waiting for mission control to cook up a rescue plan!"

I have been experimenting with landing base components on laythe using just a small parachute, and then a couple of sepratrons for a final braking burn prior to touchdown. It is hard and does takea lot of planning, but the advantage is that you can fly all the way to laythe using electric engines and to do not need to pack a heavy chemical rocket at all which dramatically reduces the payload to orbit and hencevthe size fo the rocket. Ouf course it also means lots of long difficult burns that also require lots of planning - but then this is rocket science, it is not supposed to be easy.

What is this wind of which you speak? Did you not know - there is no weather on Kerbin (well, unless you have added some witha mod!)

Just showing off guys. I have been doing some fiddling with Mechjeb's handling of parachute landings and have got it to within 20m of the target. More refinements to come.....