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Save fuel by flying a stock gravity turn to orbit This is a competition in KSP version 1.2.1 to launch the stock "Kerbal 1-5" from the KSC launch pad to low Kerbin orbit, with as much fuel left over as possible. Motivation for challenge My interest for this topic recently rearose when this question was asked and discussed. I haven't played much recently, but I remember how difficult I found it to estimate the fuel needed to get to orbit back in KSP ver. 1.0.4. According to the guides and forum posts you are supposed to fly a gravity turn to save as much fuel as possible. Most of the posts I found however aren't necessarily entirely up to date to the newest KSP versions. We will soon get KSP ver. 1.2, and then while the modders are busy updating mods I thought I would get someone to answer the above question, by kerbally kunningly masking it as a 'challenge'. In short, I am curious how much fuel I should expect to have left once the Kerbal 1-5 reaches LKO. At first I had less than 30 units of liquid fuel left (the near vertical approach). Now I am up to a shade over 40 units. It can probably be improved substantially still. I will soon add detailed rules (none of the easy tricks, like adjusting the thrust limiter, are allowed), and explain the scoring (a slight variation on the number of unused liquid fuel units). Vanilla rules The idea is to find out just how much fuel the stock "Kerbal 1-5" rocket model has left, when flown to low Kerbin orbit as suggested by the design. When I say suggested by the design, I mean that the strange extra docking port should stay on, and the thrust limiters should stay in place too. Attempts should be flown in KSP version 1.2.1 1.2 without any physics changing mods. Difficulty settings that may affect the flight must be at the default values; i.e. re-entry heating must be at 100 %, and changes in the debug menus are not allowed. The launch takes place from the KSC launch pad. Any time of day is acceptable as the launch time. The vessel is the stock "Kerbal 1-5" manned by one kerbal. Changes to staging is not allowed; neither is manually staging/ejecting/activating the staged parts. You may not tweak the stock vessel in any way; in particular you must leave the thrust limiters in place. An exception to the above rule is that you are allowed to lock and unlock the engine gimbals (and/or change the gimbal limits). You are also allowed to change, disable and enable the reaction wheel mode to suit your flying style. You are not allowed to use the RCS; all of the monopropellant must be spared. Neither are you allowed to go on EVA or bump into other crafts. The target orbit is an eastbound equatorial orbit of Kerbin at 80 km ASL. Your orbit is, however, allowed to be any orbit of Kerbin with periapsis and apoapsis both at or above 80'000 m. You may manipulate the throttle as you wish, and you may take any path to space/orbit that you think best, as long as you don't leave the Kerbin SoI. You are allowed to take advantage of SAS, autopilot mods and custom instruments (e.g. time to apoapsis and inclination read outs). Challenge participation reports and scoring When submitting results please report all of the following. The challenge entry category. "Vanilla": The main/nominal category. The one described in this section. "FAR": Using the FAR (aerodynamics) mod. See below. "GOaP": The "Get Out and Push" category. See below. Any control automation used. "AP": If you utilized an autopilot of sorts. Please tell us about the settings you chose, particular if you manage to find a particular efficient gravity turn strategy. "SAS": If you did not use an autopilot, but did engage the stock SAS. "Manual": If you flew the entire mission by hand (and without SAS). The number of liquid fuel units left on board, once in orbit. The periapsis and apoapsis of your orbit. Visible heating during flight. I don't think the stock Kerbal 1-5 is prone to heat issues, but maybe visible heat effects are a byproduct of an optimal gravity turn. Please let us know if you notice heat effects, and try to describe their 'severity'. Anything out of the ordinary. Are you for instance launching at a particular time of day to take advantage of the hot (and less dense) atmosphere. Your score is based on the amount of liquid fuel left (in your FL-T400 fuel tank) when your orbit is established. In the nominal category ("Vanilla"), the score is adjusted slightly for your actual achieved periapsis and apoapsis, and given as a percentage. A percentage score is the more action packed option for a competition! The score formula is presented in a thread of its own, so that it may be discussed separately. The score formula for the stock configured Kerbal 1-5 will give you a score of roughly 15 % if you have 15 units of liquid fuel left (poor efficiency), and roughly 70 % if you have 70 units left (outstanding efficiency). The scale is not linear. Getting into (80 km) orbit with no fuel left is enough to score above 3 %, and a shade over 90 units are required to get a perfect, and probably impossible, score of 100 %. [Note: the score formula may yet be adjusted to accommodate changes introduced in KSP ver. 1.2; the score formula is updated for KSP ver. 1.2.1]. The corrections for actual periapsis and apoapsis is given for periapsis above 80 km and below 100 km and apoapsis above 80 km and below 120 km. The idea is that if your gravity turn happens to have a build-in overshoot, then you will not have wasted all of that overshoot energy (i.e. fuel) in regards to your score. All else being equal you will loose some points though, compared to a tighter cheaper alternative. The corrections are made because the challenge should not primarily be about who can hit 80 km with the greatest precision. Entries in the "FAR" and "GOaP" categories are not adjusted for periapsis or apoapsis. The unadjusted scores ("FAR" and "GOaP") are exactly the number of liquid fuel units left in orbit. The percentage score formula is used only for entries in the nominal ("Vanilla") category. FAR ladder rules GOaP intro There are already a few good (and surprisingly sane) entries in the "Get Out and Push" (GOaP) category, so let us write some 'formal' rules for the GOaP challenge part. A group of dry and boring optimizer consultants have visited the Kerbal Space Center recently. Their report suggests to reduce the number of Rapid Unplanned Disassembly events and to layoff Kerbals. After reading the report Max L. Kerman quickly drew up calculations showing that the savings necessary to solve the current funding crisis can be achieved by a combination of flying more efficient gravity turns and a bit of creative tinkering. It is now up to you to show that the Sunday launches of the Kerbal 1-5 are not just leisure trips to orbit, but in fact important "In Orbit Fuel Contingency Reserve" missions. You do that by displaying that the Kerbal 1-5 has a viable amount of fuel, that it may function as an orbital refueler, i.e. have as much fuel as possible left over once in orbit. Not all of the tinkering is quite aboveboard, so there are restrictions as to which actions you may perform below 1000 m above sea level. GOaP rules Leader board (vanilla template) Eidahlil; 39.22 %; KSP 1.2 Gordon Fecyk; 37.66 %; KSP 1.2.1 (video included) tg626; 33.37 %; KSP 1.2 (a touch below 80 km) emaier138; 31.32 %; KSP 1.2 tseitsei89; 41.37 %; KSP 1.1.3 (score suspended) mk1980; 41.29 %; KSP 1.1.3 (score suspended) "Name"; "Efficienty score"; Comment Leader board (FAR and GOaP)