PLAD

Thank you. Another Pascal programmer!! I look forward to comments and pointers from others. It's that old developer's trap, when I write the thing I get a feel for its weaknesses and unconsciously avoid them rather than pushing them past their limits. I think I've already found and fixed the hyperbolic bug but I need to test all sorts of situations (I just found a Kerbin-Jool-Eeloo flyby!) to be sure, but I can't think of as many as a group of people can. Thanks again, PLAD

Let me be the first to post a bug report for my own software... Someone wondered in another post whether there were one could launch from Kerbin fly by Duna, and continue on to Jool. I hadn't tried that yet so I gave it a look. I searched around the 1st Kerbin-Duna low-energy window (About UT Earth day 30-90) and found something pretty quickly but there were 'fake' results mixed in. This shows the details: To reduce calculation steps I made the Lambert unable to handle solar hyperbolic trajectories, since they are very bad for flybys (a planet can't turn you much when you are moving too fast). The program is supposed to skip any hyperbolic path it finds. I thought I caught all the ways that a hyperbolic can slip through, but obviously I missed some. Bug Hunt!! I have a spreadsheet that I made when I was developing my algorithms. It is tricky to use but quite powerful. It can verify any flyby path, enter the info in the green cells, if you see the "NUM#" error you will know a path is not valid. Here you go. Don't touch any pages but the first unless you know what you are doing! (Or you have a copy stored somewhere.) https://www.dropbox.com/s/slntsw4l8vaw0mv/LambertE.xls Quick instructions for the spreadsheet- Enter the planets, UT dates (24-hour days and 365-day years only), and boost/deboost altitudes in the green cells as you see fit. Then adjust the values in the yellow cells by changing the dates in the green cells, until the pairs of yellow cells are roughly equal to each other. So cell K9 should equal K10, and if you have a 2nd flyby cell K17 should equal K18 and if a 3rd flyby K25 should equal K26. You are making the incoming and outgoing speeds relative to the planet you are flying by the same-the key requirement for a coasting flight. Then check that the flyby altitudes are above the atmosphere of the planet if so, you have a legitimate flyby. The green cells labeled 'double flyby ratio' are only used if 2 consecutive flybys are of the same planet- for instance a Kerbin-Eve-Kerbin-Kerbin-Jool flight would use the double flyby ratio between the 2nd and 3rd flybys. In that case you must make sure that the time between the 2 flybys are an integer multiple of the planet's period- for instance 2 Kerbal flybys must be 106.5, or 213,etc. days apart. Then adjust the flyby ratio until the relevant "Transit T.. over period" is an integer. Check again that the flyby altitudes are above the atmosphere. This double flyby method gets around the fact that the Lambert can't handle a flight that begins and ends at the same point. Feel free to ask questions, and check out my notes around the sheets for tips and tricks.

This post is reserved for version history, the development plan, and bug reports. Current version is 0.85 Release history: Version 0.1: Alpha release May 23, 2014. Version 0.11:Bug fix May 24 2014. Mostly bug fix-Eliminated an error that was causing fake results. Added dynamic graph color allocation. Truncated output fields to 3 decimal places. Version 0.2: May 29 2014. Implemented data sorting. Added an 'increment' assist for search periods. Greatly reduced the error in indicated Z velocities, to <10%. Version 0.21: June 1 2014. Smoothed the graph y-axis display by binning data in .1 day increments instead of 1.0 days. Made truncation of table data consistent. Removed some obsolete bits from the code and improved commenting Version 0.3: Jun 7 2014 Added detail box for selected flyby (double click on table entry), removed Vinf columns from output table. Moved sort buttons to bottom of table, and all columns can be sorted. Added a search progress tracking box, changed some labels. Version 0.4: Jun 14 2014 Added 4th body entry ability. Added more info to detail box. Fixed some sorting bugs. Fixed 86400 second error in detail box. Fixed crash if inclination is near -90 degrees. Fixed crash if empty row was chosen for detail box. Version 0.5: Jun 26 2014 Added 5th body entry ability. Added a converter to translate KSP's UT time (Y: D: H: M) to the UT day format that FF requires. Added a minimum v-inf field to allow daisy-chaining paths. Eliminated need to ever hit 'clear' button. Version 0.60: Oct 7 2014 Added 2-body porkchop plot option. Increased search grid to 100x100 (was 80x80 up until now). Travel time axis in graph now scales to fit the search results. Increased maximum flybys found to 4500 from 3000. Added "Equatorial prograde velocity" field to detail box. Version 0.70: this rev was only used for the Real Solar System version of FF. Version 0.80: Sep 13 2015 Added ability to select between Kerbin time (6/426) and Earth time (24/365). Added graph display options by Total dV, braking dV, Start vZ, and 1st flyby altitude. Added ability to change search grid from default 100x100 to anything. Added option for Outer Planets Mod planetary system. Version 0.82: Sep 30 2015 Eliminated the error where false positives would appear in a block resting on the low end of the travel time. Also reduced the number of true positives that were filtered out (I think to zero!). I know of no further false positives. No changes to the interface. Version 0.83: Mar 31 2016 Added a "subtract" button to allow decrementing the "Search steps per period" field as well as incrementing it. Added a new information item to the detail box, "start boost from equatorial orbit". Fixed an error in the day converter box that gave a UT day value that was 1 too high. Version 0.84: Jan 19 2007 Added option for Galileo's Planet Pack. Version 0.85: July 5th, 2017 Added Kerbol Startsystem's Kerbol planets (v0.6.1). Added Grannus to the GPP planets. Tiny adjustment to GPP's Gael SMA to match value in GPP v1.2.3 Improved the tabstop order. Changed some atmosphere heights for the OPM planets to match the latest OPM version (v2.1). Version 0.86: Sep 8th, 2017 Updated GPP parameters to match GPP version 1.5.x. Use FF 0.85 if you are using an earlier version of GPP!. Removed Vinf out from the detail box as it was redundant. Added total travel time in years to detail box. Future plans: Add double flyby algorithm to deal with consecutive flybys of a planet. Add ability to search for Juno-style flybys to Jool. Version 1.0: Beta release. Add rigorous input checking. Known Bugs: -Input checking not fully implemented, entering non-numbers in the search fields can cause a crash under some conditions, as can nonsense entries like search periods or search steps of 0 or less. -Inputting the same body twice in a row (a 'double flyby') is not captured and causes nonsense results. -Z velocity indicated becomes less accurate at high values (inclination over ~85 degrees). okder's addon for Mechjeb (See end of above post) completely gets around this. -Setting search periods steps to less than about 12 hours can cause rounding errors that give results a little outside of the real result field. KPP system's planet Hypat has an eccentricity of 0.41, well above my normal limit of 0.25, I'm experimenting with the result. It seems a lot of valid flybys are not found because the Lambert takes too long to converge for some positions of Hypat, but you can still find useful paths to Hypat, I have not found one that is not real yet. Note that the simple transfer (2 bodies only) to Hypat does not find anything. Fixing this would slow the whole program down considerably.

This is a tool that searches for flyby opportunities in the stock Kerbal Space Program planetary system. Flybys can often get you where you want to go for much less dV than a direct flight would need, great examples are the real-life Voyager and New Horizons probes. Flyby Finder (FF) can search for paths with up to 5 planets, but it cannot do double flybys of the same planet or flybys requiring deep space maneuvers like the Galileo, Messenger, or Cassini spacecraft used. It is useful for planning Opposition-class missions to Duna, or low-dV trips like Kerbin-Eve-Moho or Kerbin-Eve-Kerbin-Jool. It also can plan flybys for the Outer Planets Mod, the Kerbol Star System, and the Galleo Planet Pack. Here is a primer on using it. Here are the links to my Dropbox account. The source code is in the Flyby086source.zip, and the license and simple instructions are in the Flyby086exe.zip with the exe file. I chose the MIT License. Version 0.86 is now out (Sep 8 2017). Main changes from 0.85 are: Updated GPP planets to match the GPP 1.5x planet positions. made small changes to detail box's output-removed "Vinf out" and added a total travel time in years. This version of FF is good for KSP stock versions up to 1.3x, OPMv 1.9x, KSS v0.61 and GPP v 1.5x. Executable: https://www.dropbox.com/s/xxwbc36ztcpt9iq/Flyby086exe.zip?dl=0 Source code: https://www.dropbox.com/s/9vy075wcr8vopl3/Flyby086source.zip?dl=0 I will keep 0.85 here for a while as it is needed if you are using an earlier version of GPP than 1.5x. Executable: https://www.dropbox.com/s/6e3r3h4ltho1bge/Flyby085exec.zip?dl=0 Source Code: https://www.dropbox.com/s/lb5aj6tphv5n45d/Flyby085source.zip?dl=0 See bug notes and revision history in the next post. Here is the latest version of my Lambert spreadsheet, I use it to test my algorithms, and to doublecheck that FF is giving good results. It can do double flybys. It is not made for casual use and is not user friendly, but you can see the entire process that FF uses, step by step. It now does 6 bodies and includes the OPM planets. If there is interest I can make a version for Galileo's Planet Pack. https://www.dropbox.com/s/5i2foga1f2j9kq5/LambertHOPMrel.zip?dl=0 If you are looking for the version of Flyby Finder for the Real Solar System mod, it can be found here. If you are looking for the version that is just for the 10.625x rescale of GPP it is here. It uses a 5th-order equation of center to find the radius and velocity vectors for the planets, then a simplified Lambert time-of-flight algorithm to find the paths between them, then searches for matches on the incoming and outgoing energies, and finally checks the required flyby altitude against the planet's radius to make the necessary turn. -PLAD A new note- okder has made an excellent Mechjeb addon that takes the start day and 1st encounter day from FF, and the start orbit altitude, and gives you the best launch time and orbit to get into, then gives you an updated transfer solution once you are in orbit. It eliminates the need for a test probe.

I've sent a few probes to the Jool system as warmup for an eventual Jool-5 mission. At first I used direct missions which cost about 2000 m/s from LKO to Jool aerobraking, but I've seen a few missions in these forums that use flybys to reduce that to around 1200-1300 m/s. So I wondered just how slow one can go and still get there. And I think I have the answer. 1051m/s. This means that getting from LKO to Jool orbit takes less dV then getting from LKO to a low Munar orbit!! (which is about 1130m/s minimum) Even if you don't use the Mun flyby this is still true. I love flybys. I finally got some hard data on the value of a Mun flyby too- it is around a 60-80 m/s savings for a trip to Eve. I made a few mistakes in my mission, like leaving 15 minutes late for Mun and not launching into an inclined orbit, so I think someone could knock 10-20m/s off of this, but I don't see a way to get to Jool for less than that. EDIT July 4:Doh!! See 4 posts down. To summarize for others who may wish to try this route: -Use a node editor, Mechjeb has one and there are others. It is brutally difficult to set up a flyby without this. -Leave Kerbin between UT Y1 day 146.0 and 148.0, with around 147.0 being best. Go outside this window and the dV to get to Eve starts climbing dramatically. Note the Z-axis, or normal velocity of -110m/s which becomes +20m/s if you use the Mun. Note I had to leave late on day 147 because I had to wait until Mun was in the right position, yet another problem with using a Munar flyby. -Arrive at Eve as close to UT Y1 day 195 and 17 hours as possible. Try to arrive a few hours earlier if you left Kerbin early on day 146 or a few hours later if you left Kerbin late day 147. This is the tightest window in the flight (except for Mun if you do that). If you arrive at Eve on D197 the flyby will have to be in its atmosphere (i.e. impossible), and if you arrive earlier the delta V required goes way up and eventually a big maneuver will be required after the 2nd Kerbin flyby to get to Jool. -The first Kerbin flyby is around Y1 D296 and a few hours. If you flew by Eve at the right time you will have no choice but to arrive at Kerbin around the right time, just be sure to set it up before the Eve flyby so it is cheaper. Adjust the orbit between the 2 Kerbin flybys so that it has a period exactly equal to 2 Kerbin years, and make its plane be as close to Jool's orbital plane as you can tell by eye. That will be good enough. You will have the problem that you cannot set Kerbin as a target while you are in its sphere of influence (SOI), but if you set the period of the orbit right, as soon as you leave Kerbin's SOI after the 1st flyby it will be easy to set up the 2nd Kerbin flyby. -As always with flybys, set up the Jool encounter before the 2nd Kerbin flyby. The Jool arrival time is quite variable, it soaks up any errors you may have made earlier. Earliest arrival can be around Y3 D71, to as late as Y3 D200 if you arrived at Eve late and just skimmed its atmosphere. Using a Mun flyby is tricky, I wouldn't try it until you have a some flyby experience. I wouldn't have studied flybys if it hadn't been for Jasonden's 'Inspiration Kerbal' flyby challenge and then Otis' 'Lowest delta-V to Moho' challenge, if you guys read this, thanks! Good luck!

That was absolutely brilliant, both in the logistics and the astrodynamics. A 25 Year Mission- the crew of the Enterprise should be embarrassed!

Thanks! I love the math. Now the other way. I had not looked at going Kerbin-Eve-Duna and then flying directly back from Duna to Kerbin because the NASA study points out that it would be bad for humans to arrive at Mars after a longer flight. A Venus flyby on the way to Mars is therefore is generally not preferred for humans. But careful studies have shown that Kerbals are not affected by long periods of zero-G, so why not? It turns out there are not as many of these flights though because the synodic period between Kerbin and Eve is 170 days unlike the Eve/Duna of 97 days. It also take more energy to go from Eve to Duna so you have to arrive at Eve with more energy and the start boosts are bigger at around 1200-1500 m/s. On the good side returning from Duna to Kerbin is much cheaper, as low as 650m/s, so overall you save delta-V by going Kerbin-Eve-Duna, land, Duna-Kerbin instead of Kerbin-Duna, land, Duna-Eve-Kerbin. But it takes longer. Here's a quick look at the best one in the first 3 years: KeY1D166, 1237m/s Z+850 -EvY1D214 -DuY1D244. You have a huge amount of leeway on the return from Duna to Kerbin. If you leave right away it's DuY1D245, 858m/s Z+38 -Ke332, but you can leave anytime in the next 29 days and the delta-V required just keeps dropping until a minimum at DuY1D274, 640m/s Z-32 -KeY1D341. So 166 to 175 days duration, total boosting around 2100m/s to 1900m/s. There is that 5000m/s arrival speed at Duna to deal with though, I bet you'd have to aerobrake down to about 8500 meters to be captured. I had a weird problem when trying this, the encounter graphic would disappear when Kerbal would normally switch from the little white arrows to the colored ball that indicates you will pass in to the SOI of the target planet. So I had to guess and I missed the launch time and had a 111m/s error to correct. Doh! So I gave up for now. If anyone does this whole flight I'd love to see it.

My first trip to Duna was a conjunction-class mission, that is, I went there and back on near-minimum energy trajectories. These are about 1050 m/s from low-Kerbal orbit (LKO) to Duna and then about 650 m/s from low Duna orbit to return to Kerbal. The problem is that I had to wait at Duna for 146 days for the return window to open and I only had a few days worth of stuff to do with this first tiny mission. The whole mission was about 280 days. So I started looking at higher energy missions, often called opposition-class missions. Here is a little NASA paper that looks at the two mission types for more background. http://nssdc.gsfc.nasa.gov/planetary/mars/marsprof.html NASA has found that opposition missions can be much faster for not too much more delta-V if you can flyby Venus on the way to or back from Mars. So I searched for such opportunities using Eve in KSP. And hooboy did I find them. The synodic period between Eve and Duna is 97 days and it turns out that there is a path from Duna, flying by Eve, and arriving at Kerbin with no thrusting required after you leave Duna (except for correcting small errors) every single synodic period! The delta-V required at Duna, assuming you start in a 60km circular orbit, varies between 1100 and 1300 m/s. Most take too long to get from Duna to Kerbin (up to 200 days) and others leave too late to beat the next conjunction window back to Kerbin (so why bother?). But 2 are quite fast, and here is the best one. Only 1 day on Duna though! I am working on a program to find flybys and right now, and I am confirming that the results are real by flight-testing them as well as determining what information is needed to make it easy to find the right path. Here is how I describe the flight shown above: KeY2D154:1145m/s Z+48,-DuY2D205:land: DuY2D206:1123m/s Z+248,-EvY2D264.5 -KeY2D310 That's 'leave Kerbin on Year 2 Day154 (Assume 0 hours if not mentioned) with a speed of 1145m/s (above the circular orbit speed you already have) that has a normal component of +48m/s, arrive at Duna on Year2 Day205, land ( or do whatever while there), Depart Duna on Y2 Day206 with a speed of 1123 m/s with a normal component of +248m/s, flyby Eve at Year 2 Day 264.5 (so day 264 and 12 hours) and arrive at Kerbin on Year 2 Day 310". I find that with just the start speed and the time of flight I can find the right path with the node editor, though I have to search a bit. Oh, and you have to know that I always start in a 75x75km orbit at Kerbin, 60x60km at Duna, and I always use 24-hour days and 365-day years. So this flight was 155 days total with about 2300 m/s in the two orbit departures. A conjunction-class mission is about 285 days and 1700 m/s for comparison. Here is the fastest mission before Y4: KeY1D58:1288m/s Z-3,-DuY1D94:land: DuY1D95:1298m/s Z-427,-EvY1D146 -KeY1D166 108 days for about 2600m/s. But at these energies there is a direct return to Kerbin that is 100m/s less and just 3 days longer, so this one is not too useful either. If anyone asks, I can give all 10 of the first Duna-Eve-Kerbin flybys and leave it to you to decide the best way to get to Duna in the first place.

Oh Otis, you had to suggest a Munar flyby....... I thought I could match metaphor's spectacular 11-flyby flight, but I just couldn't do it. It's not just the good ideas, it's the careful execution and I'll bet a lot of practice. donfede, is there a KSP current thread discussing Lambert algorithms somewhere? My spreadsheet uses a 5th-order equation of center to determine the planet locations and then a simple Lambert algorithm to find paths between them. The usual stuff. It's not quite fit for human consumption yet though. I would imagine that numerous people here have already been through this.

Kasuha has shown another innovation I hadn't considered. By Injecting energy at an Eve periapsis one reduces the boost required at Kerbal and the deboost required at Moho. At first I thought it would all come out even, but Eve is a lot heavier than Kerbal or Moho so the Oberth effect should be greater at Eve. It also adds flexibility to the whole mission as you can compensate for errors, and have wider launch and arrival windows, by adjusting the size of the Eve boost. I think. Can't try it for a few days, alas.

Me again, last entry for this challenge I hope, my honey-do list is being neglected. I pulled out all the stops and put some good ideas others have had to use. I've put as many of the details into the album as possible so anyone can imitate this. The path has some margin from Kerbin to Eve, and Eve to Moho, but the Eve to Eve flyby dates are critical. This is how I'm flying to Moho from now on. Lucky timing or a slightly better window in later years might still knock a couple hundred m/s off of this. Jasonden flew back! I bet with luck you could take this general path back for about 2300 m/s. I'd like to see that.

That Reddit post that Kashua pointed to really opened this up for me. I had done a 2-dimensional calculation of the minimum speed you can arrive at Moho with if you take a Hohmann path to it from Eve. I came up with about 2200 m/s if you went from Eve's periapsis to Moho's apiapsis, ignoring plane changes and the fact that those 2 apsis aren't 180 degrees apart. Close enough, I thought. Then I saw the Reddit post enter Moho's SOI at 1700 m/s. Another beautiful theory shot down by an ugly fact. So I ran Alex Moon's pork chop plotter and discovered that the Moho approach speed for Eve-Moho can be as low as 1100 m/s! Further study showed that this only happens when you leave Eve when Eve is near it's furthest point below the ecliptic plane, and arrive at Moho when it is near it's highest point above the ecliptic plane. The Eve position is much more important, so you must leave it within a day or so of day 144, 210, 276, etc. (keep adding 65.5 days). There are 2 problems with this- it costs a lot of dV from Kerbin to arrive at Eve while it's so low, and it is not possible for Eve to change your approach from Kerbin enough to head to Moho. The flyby would have to be at about 550km below Eve's surface. But doing 2 Eve flybys can solve that! The first flyby adjusts the inclination to match Moho's, and the 2nd lowers the periapsis. 8373 m/s total from surface to surface. I had to find a flight from Kerbin to Eve that arrived 65.5 days before a good window from Eve to Moho. It was fun. Note I only made small course corrections after leaving Kerbin, a first for me. I only looked in the first year. This can clearly be beat, I think the theoretical minimum is about 750m/s less. (Double dare ya!)

A very useful challenge. My first time to Moho I was using an Ion motor so I'd have lot's of spare dV, and then I discovered I couldn't kill enough speed while in Moho's SOI and flew right on by, thrusting the whole way! F5/F9 and I ultimately had to break for 80 minutes (real-time!), adjusting the aim every few minutes. I try to avoid the direct route now. So flying by Eve to lower both your start boost and Moho approach speed is the obvious approach. Here's how that went: Ever since Jasonden's Inspiration Kerbal challenge I've been trying to figure out flybys. I've made a spreadsheet to convince myself I understand the math before writing a program, but I can't execute the burn from low Kerbin orbit accurately enough to follow a path that has a small margin of error. (KSP Trajectory Optimization Tool nails this!) At least it shows me roughly where to look. In the first year UT I think there are two windows, one leaving Kerbin around day 138-144 and arriving at Eve around day 160-170; and one leaving Kerbin around day 310-320 and arriving at Eve around day 350-360. The first window doesn't have any quick routes to Moho (multiple sun orbits are required) but the second window theoretically has one that I show in the last frame. It also aims you nearer to Moho's Apoapsis. If you want to keep the total dV lower than a direct flight I think these are the only windows in the first year.

Hooboy, this one has grabbed my free time lately. First a mention on my earlier post- I agree with von Ziegendorf- multiple flybys have scientific value, witness Mariner 10. So restricting points to 1 score per planet is not optimal. As v-Z and donfede touch upon, total flight time is the important thing when a life form is on board, and the current scoring deals with that. Donfede's post above gives a pork chop plot of departure date versus flight time for Earth-Mars-Earth free return missions. I've been slowly making one like that for Kerbin-Eve-Kerbin. Doing it by hand is too slow to try for long, but I think it can be done with relatively small modifications to a pork chop plotter. Here is the algorithm I'd use. Note that only 2 pork chops need to be made, one could then put those two in memory and most of the program is comparing the points in those two 2-dimensional arrays to find free returns. The next step is to determine flyby periapsis requirements and rule out the impossibly low ones, then finally plot the results as below. I bet some of the sub-100 day free returns are possible. I ran TOT for K-E-K paths launching in this time frame and it gave me one that leaves Kerbin Y1:143:21 at 1136 m/s, flies by Eve 50 days later, and returns to Kerbin 144 days after leaving. It clearly searched for the solution with the lowest initial dV from LKO. There are solutions at least 30 days shorter, but needing at least an extra 100 m/s. Are the values for the Kerbol system orbits correct as given in the wiki? Better yet has someone got a VSOP-type set of terms for their orbits? I'm guessing there are no perturbations involved in the Kerbol system motions at all so there would only be one set of terms for L B, and R for each planet. Note that this method would apply to any free return flyby missions, you could keep using the arrivals at each planet to quickly search for paths to the next planet. We need a way to deal with paths that flyby the same planet twice though. Enough for now. This is an instructive challenge!

Well done donfede, Dres requires a lot of MCC and time to get to. I particularly like your habitat and the mission architecture, it's got a nice touch of realism. I've been wondering how the TOT works, and what paths it might throw away when searching for the best one, and I think I've come up with a way to use a pork-chop plotter to find flyby and return missions. See the pictures below. My thanks to the author of the plotter I use in the example, which was linked to earlier in this thread. And I haven't read more than a few hundred threads on this forum so far, so my apologies if someone found this already. It uses the fact that during a flyby the speed you leave the planet at will be the same speed you arrived at, relative to the planet. So finding an ejection speed that matches the insertion speed (at the same altitude!) guarantees that the flight is theoretically possible. The only thing that makes some of the solutions impossible is that they require a flyby periapsis lower than the surface of the planet (or its atmosphere). Every point on the original pork-chop defines a line in the second pork chop (I call those pork slices, ha). Some slices have no points that have the desired ejection dv, but a lot have 2 or more. You could make a 3-d graph up from the original chop, you would end up with a bunch of points indicating where the free-returns are. I suspect that they would appear as closed ellipsoidal blobs whose surfaces defined all possible solutions. Is this what those 3-d graphs that TOT flashes while it is searching are? For multiple flybys you would take one of the points found on the 2nd pork chop and use it to make a 3rd plot. The odds of finding something are surprisingly high if you start in the zone of the first pork chop where the departure speeds are not too far above the minimum, since when it's too high the target planet can't change the path much, or too close to the minimum, where there isn't enough energy to give a large range of orbit sizes.

Um.. I don't think von Ziegendorf should be called 'bottle rocketeer' anymore. Is 'Master Astrodynamacist' or maybe 'Gauss's Daddy' available? I do suggest a scoring change though. How about in the event of multiple passes of a given planet, only the best of those passes is used? Thus you can only get flyby points once for each planet. A spectacular flight like the Flyby Frenzy would still win by a mile. And you could avoid brute force flights like what I'm looking at now, where one could fly by Moho and get into a 51.3 day orbit that keeps returning to Moho, you can keep the period at 51.3 days by flying by above and below Moho (as seen from the sun) so that you are only changing the inclination of the orbit rather than the SMA. Another 40000 points every 51 days until you run low on monopropellant, then take the next window home. It could get high points but is quite boring. As a last word on Moho flybys, if your periapsis was to be at Lat 35S, Long 174W it could be as low as somewhere between 150 and 200 meters. I looked around for a place where the periapsis could be zero or lower, I was going to claim that the log of zero is minus infinity and thus request a score of infinity, but nowhere on Dres or Moho is low enough.

von Ziegendorf- Um Gottes willen!! 3 flybys and return is spectacular by itself, but you did it with only 88 m/s (74 units)of rcs dv! That's a real free return. Could you tell me what KSP UT day the mission launched? I want to try that.

I noticed that a transfer orbit to Moho has a period of about 67 days or so. 3 times that isn't much less than 2 Kerbin years, so if one could pick up a little energy from Moho there might be a 2-Kerbin-year round trip possible. And here it is. I was laughing like a nut during the flyby, for an instant Mechjeb's 'altitude above surface' was less than 300 meters. At 4.4 km/s. I wasn't quick enough to catch that or the KSP indicated periapsis of 1594 but I'm happy with the 1602 meters I recorded. I needed every m/s I could get from Moho so the low pass was necessary, but no sane pilot would do this. And yes, I used F5 before my first try but we shall not speak further of why an F9 was needed. B=2 for Moho, Periapsis=1.602km, U=303 units, D=226 days, M=182 tons, LKO dV=1623 or 1746 if you count that correction out past Minmus. Score 45044? Now on to multiple flyby missions.

donfede- good idea there, I've installed Alarm Clock to give a clear indicator of the UT of events. My Duna mission had an MET of 0 at UTY1, D50, H21, M46; and it started the trans-Duna boost from LKO at UTY1:61:18:52. Is there an agreed-upon way to indicate the KSP UT of an event? Or is this OK? Metaphor's Duna mission had a nice short flight time and close flyby- much superior for a mission carrying living things. There might to be a 'cycler' mission possible for Duna. 2 Kerbin years is 213 days, and the Synodic period between Kerbin and Duna is 227 days. If we can stretch a 2-year conjunction class mission by 14 days by raising the apiKerbol and dropping the periKerbol enough to cross Kerbin's orbit twice... but Duna might not have the mass to pull it off...

Here's my opener. First the pictures: I feel I might be violating the spirit of the challenge with that 228 m/s burn even though I did it using only monopropellant. In my defense I give the example of the way Cassini was flown to Saturn with it's VVEJ path. On 3 Dec 1998 it made a "Venus Targeting Manoeuvre" of 452 m/s to allow its 2nd flyby of Venus. Since it was in deep space at the time the low thrust didn't matter. There is free return path to Duna available every time Kerbin approaches Duna. You just go for a 2-Kerbin-year orbit that will bring you right back to Kerbin in 213 days. Just time it so you pass Duna at one of the 2 points you cross its orbit. If you make the flyby at a far enough distance Duna won't affect your path enough to matter. For a better flyby you can then tweak the path to go closer to Duna and correct the timing to get you back to Kerbin. If you allow a fair-sized burn at ApoKerbol there is a large window of opportunity. It's easy with Duna because it's orbit is coplaner (close enough) to Kerbin's and has a small enough SMA. Eve is much tougher because of it's high inclination. I think your flyby of Eve was much more interesting than this flyby of Duna. However, the scoring system heavily favors Duna. I think this gets: B=2 (Duna), P=192.214 km, DV=1252 m/s, D=225 days (or 215?) U=270 units, M=182 tons. Score 24783? I love the complicated scoring systems, they make the analysis more interesting. I bet there's a 60000 point path to Duna/Dres out there.

I'm new to the forum, but if you're still taking entries here's mine. I assumed Werner Von Kerman was about to retire and didn't care if Kongress fired him over the fuel use. And that the Krussion flight was almost to Mun before Jeb could launch. Zero Hours, 43 minutes, 33 seconds from launch to the flag plant. 61425 fuel at launch. I first tried a huge-DV rocket but I couldn't get the big numbers AND high acceleration all the way. Most important for me was when I began the deceleration. Even 10 seconds too early (at 7km/sec!) will cost you many minutes of slow coasting if you brake too soon, and of coarse a spectacular splat if you're 1 second too late, given the somewhat aggressive landing vector I chose. I'd have added another stage to the booster but my computer was getting quite slow. What do those people use who have 100+ orange-tank boosters?

Hello Jasonden, I actually have 4 entries but they are scattered about, and it is ambiguous which one I'm referring to in a given spot. Doh! I posted 2 entries that use the single-Kerbal capsule, one with MOR (26.63 tons, score 7.51) and one direct (19.10 tons, score 10.47) to compare MOR to direct. Then I saw that using two of the lighter single-person pods would get a higher score so I did another direct entry (24.79 tons, score 16.10) this time with 2 kerbals, and finally a KOR entry using that same 2-kerbal landing craft (13.41+12.95 tons, score 18.04) to compare KOR to direct. I can't bring myself to do a 2-Kerbal MOR entry because I know it will be inferior to the direct and KOR entries. I never included albums of the single-Kerbal MOR or direct flights, (I only learned how to do that last night!) so here's the single-Kerbal MOR flight. Here's the single Kerbal Direct flight for comparison: Looking back, I should put better titles on my posts.

OK here is my final entry, using Kerbin Orbit Rendezvous. It uses the same 2-Kerbal craft as my direct-to-MUN entry. It uses 2 identical launchers. I throw my entry to the mercy of the court however, as you will notice that I was about 1.5 m/s short of a clean return to Kerbin. But they made it back to the surface alive! If I understand the scoring, this would be 100/(13.41+12.95tons) times 2 Kerbals, times 2 (for no aparagus), times 1.189 (the 4th root of 2) = 18.04. Here is the complete flight for my direct-to-MUN entry, I had previously posted just a picture of the launcher. Note that I had 11 m/s left at the end of that mission. You will gather that I don't like to waste delta-V carrying fuel, at least as long as I'm not in the capsule. Here's my take on direct versus KOR. I think that NASA contemplated EOR when they weren't sure they could build a launcher big enough to put everything in orbit in one go. All KOR does is allow you to use smaller launchers, but at the cost of the extra weight of the docking gear, thrusters, monopropellant, and rendezvous delta-V. As such the two smaller launchers will always weigh more than the one big one. Here it cost me 1.6 tons total launch weight. I loved this challenge. I'm looking forward to Challenge II. Duna?

Hello, A final note and bit of knowledge for those who may visit this thread in the future. Sal and AlamoVampire's suggestion worked perfectly, by just putting the small letter-and-number code between the IMGUR brackets the album displayed correctly. However I then went back to imgur and deleted the little test album I had made for this post (I'm always trying to keep my inbox and whatnot as uncluttered as possible). I also wondered if this forum keeps copies of the pictures and albums once they are linked. I now see they do not, which makes sense, but hey, now I'm sure. So future viewers who see this post will now see the imgur error screen where I say I successfully put the album and wonder if it didn't work. Sorry about that. It worked.

WOOOHOOOO!!! Thank you!