PakledHostage

I attempted this challenge 3 times before I got a capsule to land within the KSC compound. The others two times, I landed within sight of the compound but outside the flat area. As fun as it was, there\'s definitely an element of randomness in this challenge... You\'re moving at 2 plus km/sec at the time of your de-orbit burn so even a small timing error can make a big difference in where you come down. And in playing around with precision de-orbiting, I\'ve found that the amount of time that it takes you to reach your target speed during your de-orbit burn can cause variations in where you come down of several kilometers. So here\'s my submission even though I don\'t know if you\'ll count it for points. My landing module didn\'t include any nukes (my Kerbals are pacifists) and I used an external 3rd party re-entry planner. It isn\'t really clear to me from reading your write-up whether all re-entry planners are disallowed or only just in-game ones. The re-entry planner that I used wasn\'t an in-game module. It was an external one that I wrote for my Mercury 'Friendship 7' Commemorative Challenge. Here are the screenshots:

Yup, patched conics together with rudimentary celestial navigation for the escape burn... I timed my burn with reference to Kerbol\'s rise time from my 196 km high circular parking orbit. I then used a numerical model to plan the aerobraking manoeuvres and de-orbit burn upon returning to Kerbin. I\'ll admit that I blew the aerobraking manoeuvres twice before this successful mission though. On the first try, the capsule re-entered on the first pass, then on the second try the capsule wasn\'t captured at all and I lost the crew... If I get a chance this weekend, I\'m going to try to modify my aerobraking prediction so that it can handle hyperbolic starting trajectories. Currently it assumes an elliptical starting trajectory. PH. Edit: After finally getting around to modifying the aerobraking prediction to handle hyperbolic starting trajectories, I used it to find some interesting results: Intercepting Kerbin from a 1/2 year orbital period Kerbol orbit with the stack that I used in the mission described above, your aerobraking window is only about 2.4 km wide at periapis. Specifically: - Hyperbolic periapsis of ~28.5 km results in capture on the first pass - Hyperbolic periapsis of ~30.9 km results in a roughly parabolic escape trajectory. (These values were calculated assuming a Hyperbolic excess velocity of 3314 m/sec.) In my first attempt, I used 25 km and re-entered directly. In my second attempt, I used 35 km and didn\'t manage to get captured by Kerbin\'s gravity. May my crew rest in peace... In my third attempt, I used 31 km and closed down the orbit to about 12000 km apoapsis using the RCS. That used up about 25-30 percent of my RCS fuel. Fortunately, I had enough left over to make another three aerbraking passes and to align the orbital plane to the equator. If I were to try it a fourth time, I\'d probably aim for a 30.1km - 30.3 km hyperbolic periapsis.

I\'m going to submit a new entry for this challenge. As chuffed as the boys are about being invited to ride in the back of the pickup truck in the parade around the Kerbalville shopping centre, they\'re still hoping for better... Maybe some commercial endorsements? (Jeb says his dream is to make it onto the Wheaties box.) Here goes: Does this count as the smallest standard parts rocket? 10-1/2 LFTs and an RCS tank? I could have saved a bit more fuel by going for a 2-year mission rather than a 1-year trip. I strive to bring my spent stages down over water. I wonder if damage to greenhouses, etc resulting from falling boosters will ever be considered in the game? Orbit closed down to an 85 km high circular orbit after four aerobraking passes. Ready for re-entry. Jeb somehow managed to misplace the post-it note with the splashdown coordinates but it was on the order of 5 km from the pad. I generally aim a little long so that they come down in the water. While I\'m on the subject, I created a handy spreadsheet for calculating Great Circle distances between any two points on Kerbin. I previously posted it in the How to land where you want on kearth thread for anyone who wants a copy.

Hmmm. That\'s not what I\'m experiencing. The raycast function also returns a hit distance. Its value is consistent with altitude AGL. In my case, I still get an altitude when I hover over (or land in) the water. I assume that the value I\'m seeing is the distance through the water to the 'bottom'? Maybe I need to fly further off shore to see the effect you\'re seeing? Have you tried hovering over the water close to KSC? What happens for you?

You are right, but in order to use your suggestion, the module would need to detect whether it is over water or not. The layerMask selectively filters out colliders when the raycast function is called. I suspect that water has its own filter bit in the layerMask. Maybe I\'ll just have to experiment to figure out what it is.

Thank you Harv! That seems to have worked. Now my next question is: What bit should be set in the layerMask so that water is also detected? The raycast function doesn\'t seem to detect water when only the 15th bit is set? I\'ll test it some more this evening.

This might be obvious to some of you, but I haven\'t been able to figure it out: Which structure/class contains the ship\'s altitude above ground level (or the ground elevation at the ship\'s location)? I\'ve tried the following code in my \'onPartUpdate\' handler: Vector3d dR3Position = vessel.findWorldCenterOfMass(); dASLAltitude = vessel.mainBody.GetAltitude(dR3Position); dLatitude = vessel.mainBody.GetLatitude(dR3Position); dLongitude = vessel.mainBody.GetLongitude(dR3Position); I\'ve then used those values in \'GetRelSurfacePosition\' and \'GetWorldSurfacePosition\'. Both these functions take Lat/Lon/Alt as inputs. I assume that the return value for \'GetRelSurfacePosition\' and \'GetWorldSurfacePosition\' is a vector describing the distance between the ground at some reference location and the specified lat/lon/alt. I hacked at it for about an hour last night (using a callback function to display various values to the screen) but I couldn\'t find an algorithm to output altitude above ground level. I only seemed to be able to get various incarnations of altitude above sea level... I would have thought this should be easy. What am I missing? Thanks in advance to anyone who can point me in the right direction.

Has anyone else had the thought that maybe all these generic Kerbals should be wearing red uniforms?

Come on, Iskierka, you know that I used a non-rotating cartesian coordinate system and that it was appropriate to do so for the purposes of that example calculation. You also know that the units work out. I used MathCAD, which is 'units aware'. Multiplying deg/hr by m/sec can yield a result in g because the unit conversions are done internally. There\'s already been so much negativity on these forums over the past couple of days, can you maybe try to do your part to improve the situation by improving the tone of your posts? You\'re obviously very knowledgeable, but the sniping tone of so many of your posts is tiring and diminishes your otherwise valuable input. Thanks. PH.

I\'m not a gamer, but something about Kerbal has captured my heart. The last time I got this addicted to a game it was to Microsoft Flight Simulator... (I won\'t say which version because I\'d be dating myself). And while various incarnations of the Simpson\'s 'Comic Bookstore Guy' do rear their heads here on occasion, I enjoy reading these forums. People\'s posts are often funny, occasionally impressive, and I almost always learn something new. Thanks Squad!

I think he\'s looking at it 'from the top down', in the equatorial plane. When viewed in that 2D plane, the spacecraft launches outward from the edge of the rotating disk. Even so, the effect is small. The highest speed that I\'ve ever seen while attempting this challenge is about 590 m/s. By the calculation below, the coriolis acceleration at that instant would be only 0.035 g.

It happens... Who\'s going to throw the first stone? Not me. This could be an interesting challenge... It might come down to who\'s got the fastest computer (i.e. who can launch the biggest monstrosity without lagging out their system), but it would also require navigational skill.

Looks freakin\' awesome! Why not post it to KerbalSpaceProgram.net or one of the other sites that hosts add-on parts?

I played around with this between Christmas and New Years, back when I was still running into the altimeter blanking bug on every flight (thankfully that went away when Rev 0.13.1 was released...). These were some of the screen shots that I captured then: I did it a bit differently than some of the other posts that I\'ve seen here, but I too went for minimum time in space while using the smallest rocket that I could get away with. The boys are hoping that they\'ll still be asked to join the ticker-tape parade! I could probably build a better rocket than this now that I know that LFT stacks can be connected to a radial decoupler, but that was how I did it then... All parts are stock except the one Silisko Industries LM-03 fuel tank on my middle 'orbit circularisation stage'. I use that intermediate “orbit circularisation stage†to enable me to trim my parking orbit without having to activate the RCS or top booster stage. That way, I have a precise starting mass for my inter-planetary orbit insertion burn and the spacecraft will accelerate the way I expect it to. The reason that I needed a precise starting mass for the inter-planetary orbit insertion stage was because I flew a quasi-free return trajectory. I had only 4 RCS thrusters and one RCS tank to steer the boys back to Kerbin. They needed to be on exactly the right heading when they left Kerbin so that they\'d make it home 106 days later. Yes, this image is photoshopped! But it saves me having to upload one image each for periapsis and apoapsis. I understand that heating effects have been added in v0.14. It may no longer be possible to get within 3.4 million km of Kerbol. But it was possible in v0.13. 100 days and two orbits of Kerbol later Trimming for a survivable re-entry Just before splashdown after 106 days in space. They boys made it home to Kerbin, but they\'re still a long way from KSC!

Please forgive the bump but I thought I\'d add some more screenshots following some refinements that I made to my re-entry/aero-braking model. They may be of interest to anyone wanting to develop their own re-entry/aero-braking models because they appear to validate Kosmo-not\'s atmospheric density profile: 62.3 m/s delta V deorbit burn at 7:30 after KSC antipode overflight 82.5 m/s delta V deorbit burn at 6:41 after KSC antipode overflight 204.2 m/s delta V deorbit burn at 7:01 after KSC antipode overflight

I\'m puzzled by that too, Iskierka. Based on this post, it sounds like you\'ve tuned your model to a flight test where you had the throttle set at 50%. But how do you know that the throttle was set precisely to 50% during that test flight? Is there a precision throttle setting readout somewhere in the game? Further along, this post suggests that your model is out by 100-400 m when you compare its results to a full throttle test flight. An imprecision of as little as ±1% in your throttle setting during the 50% throttle 'tuning test' could easily account for that 100-400 m error. (For example, my spreadsheet predicts ±1% variation in throttle about the 50% setting results in about ±75m variation in apoapsis for this spacecraft configuration). It would help us all out greatly if you could provide more details about your method. Could you maybe provide a table showing how well your current model correlates to the in-game physics? It would help us understand how robust your model is to variations in the basic paramaters, and will allow us to interpret the validity of your results when you attempt to account for the more subtle effects.

I got lucky. What\'s that about the Infinite Monkey theorm? PH.

I\'m back in the black... I\'ll leave it to the judges to determine whether it counts as 33487, 33488, or something in between.

I\'ll tell you how I do it, but I\'m not an expert on this subject so please take everything I say with a grain of salt: I start by going straight up then pitch over once I\'m through the densest portion of the atmosphere. Opinions seem to vary on the exact timing, but I don\'t pitch over until upwards of 12000 m - 15000 m. The tricky part is picking the right initial pitch over angle. Too vertical and you\'ll reach your target apoapsis without any horizontal speed. Too shallow and you\'ll waste fuel going fast down low where the air is dense and the drag is high. Following pitch over, I execute a gravity turn while toggling back and forth between the main view and the map view to keep an eye on my apoapsis. As my apoapsis nears about 10 km below my target value, I pitch over some more to align my thrust with the horizon. By this point, the air is (hopefully) thin enough that the extra drag due to misalignment of my rocket from the direction of travel is minimal. I use the angle that I have to pitch down to align with the horizon as a measure of how well I\'ve executed my gravity turn (less is better). Beyond that, there\'s currently an exhaustive discussion about maximizing launch fuel economy going on over in the topic=7161.0'>Mini-challenge: max altitude with this supplied spacecraft thread. You might also want to have a look at that. PH. Edit: Clarified some wording

The gauntlet has been thrown! To the pain!

Here\'s my best effort so far... Not quite good enough for third place. Two metres shy!

[cricket, cricket, cricket....] Well, I guess I\'m on my own then... I chose to approach this challenge as a technical challenge requiring pre-calculation of trajectories rather than as a 'trial and error' challenge. Using the atmospheric density and aerodynamic drag equations derived over in the Mini-challenge: max altitude with this supplied spacecraft thread, I wrote a program to predict where my Kerbal 'Friendship 7' capsule would splash down given certain inputs. My Kerbal 'Friendship 7' rocket was then launched into an initial LKO that was subsequently trimmed into a roughly circular (±200 m), 0 degree inclination orbit during the course of the 3-orbit mission. In keeping with the goals of my mission\'s namesake mission, I also observed the crewmember\'s reactions to the space environment throughout the flight. Bill and Bob reacted to the space environment with a lot of screaming. Jeb, on the other hand, was much less flappable. During the crew\'s time on orbit, I also ran the numbers to finalize the retrofire sequence that would have to be followed for them to land on target. Given that they were starting from an initial 78.4 ±0.2 km orbit, I determined that a 66.2 m/s delta V deorbit burn would be required. The burn would have to occur at 7 minutes and 32 seconds after they overflew KSC\'s antipode, as determined from the anti-target reticle on the navball. The de-orbit burn was carried out as prescribed at 1:35:15 MET, and the capsule splashed down off KSC approximately 12 minutes later.

Although I\'ve already extensively used what I learned in this challenge, I\'ve been distracted by other challenges... I\'ll give it a try when I next get a chance to play the game. I might not get that chance until tomorrow evening though. I\'ll post back with my results.

February 20th is the 50th anniversary of John Glenn\'s 'Friendship 7' mission. The objectives for that mission were simple yet technically challenging: 'Place a man into Earth orbit, observe his reactions to the space environment and safely return him to Earth to a point where he could be readily found.' Glenn\'s Friendship 7 capsule splashed down within 5 NM of the destroyer USS Noa on February 20th, 1962 after completing 3 orbits of the Earth. Lookouts on the destroyer sighted the main parachute at an altitude of 5,000 ft from a range of 5 NM. The Noa had the spacecraft aboard 21 minutes after landing and astronaut John Glenn remained in the spacecraft during pickup. Mission objectives for this challenge are similarly simple yet technically challenging: 1. Launch a chute-pod-decoupler-3LFT-LFE stack into Kerbin orbit. All parts must be stock (see spoiler below for an image showing this stack). 2. Complete 3 full orbits 3. Splash down as close to KSC as possible. Ideally in the ocean east of KSC and within sight of the space centre. Parts 1 and 2 have been completed by numerous people including myself so I know this challenge is possible, even though I haven\'t completed part 3 yet. Edit: Clarified that all parts must be stock parts.