Temstar

This, it also allows construction of ships with structures that will only survive intact fully fuelled in microgravity. For example a large 100 FL-T500 capacity propellant depot when fully fuelled will be 250kg + depot hardware. To lift this propellant depot fully fuelled into orbit will require a colossal booster like http://kerbalspaceprogram.com/forum/index.php?topic=10468.0, three times the size of the depot and impose very strict requirements on the geometry of the depot or it will simply crush the booster underneath with its sheer mass. On the otherhand launching this depot empty will only result in a payload of 30kg + depot hardware, easily within the reach of your average heavy lifter and allowing more varied shapes like long docking arms more suited for a depot.

Oh yes 27.5 tanks of fuel to bring 23.5 tanks to orbit, 46% payload fraction. I\'ll put this up in the exchange tomorrow once I get some better pictures

I don\'t think an official mechjeb is required, wouldn\'t want to make this game too easy. AFAIK all of NASA\'s docking are all done manually too since NASA never had a unmanned resupply spacecraft. Getting close to another craft is not that hard even in the current game, what is hard is to get both ships\'s docking interface to line up properly since currently any spacecraft not in focus will have its ASAS offline causing it to slowly rotation in random directions. To implement docking they at least need to have a way for ship to remember ASAS status when not being controlled. Ideally there should also be a docking helper module that knows how to rotate the ship one revolution per orbit so it always keeps one orientation relative to the body the ship is orbiting. A docking cam with a crosshair and showing distance and speed of approach would be pretty important too, other than that I don\'t think any other aids are needed. Well two ways: Method 1: The propellant depot stays exactly where it is and you send up tankers to dock with the depot and refill it. Afterwards the tanker is deorbited. Method 2: The tanker itself is the propellant depot, once it\'s empty you just deorbit it and launch another one. Both require expandable tankers, I don\'t think SSTO reusable tankers would be a good idea given their much smaller payload - you\'ll go crazy from all the rendezvous you have to make if you use SSTO reusable tankers. Method 1 is for those who like to build up a big permanent station in orbit and will be worth it if we get a lot of space station stuff like canadarms where you probably don\'t want to throw away. Method 2 needs less rendezvous but also results in less sophisticated depots. Fun fact: NASA and ULA are working on method 2 style missions using half empty Centaur upper stages

With docking and fuel transfer coming, orbital propellant depots are going to be all the rage soon. So gentlemen, in what ways do you think your game will change with the introduction of propellant depots? Me I think I\'ll be designing and launching a lot fewer giant boosters to loft spacecraft full of fuel into orbit. Once depot is in I see myself building spacecraft in a way so they use up most of their own fuel to reach orbit. Then they will refuel from depot before going about their mission to Mars or something. The fact that boosters + spacecraft\'s own engine now only have to lift an empty spacecraft into orbit as opposed to one with full load of fuel means a dramatic reduction in size of rockets needed for the same mission at the cost of more launches to refill depots. On that note I would like to see parts like 'FL-T500 fuel tank (empty)' in the VAS. Other than that I think Spacecraft Exchange is going to be full of people show casing efficient and reliable tanker designs since they will become an integral part of any long range missions.

I figure if I get started now, by the time docking and planets do come along I only have to adjust the work I\'ve done to the new version rather than start from a clean sheet. If Rocketdyne didn\'t start F1 engine development in 1955 no one would be on the moon in 1969, just look at what happened to the Soviet N1 rocket.

Aerospike is the most fuel efficient of all the rocket engines The bold part is important, it\'s not a jet engine.

I like it, imagine: you\'re in the VAB building the latest heavy booster, suddenly an urgent message from the Tracking Station flashes on screen: Torino scale level 10 impact warning Object size - approximately 10km Probability of collision - certain Projected damage - total Extimated time to impact - 18 days What do you do?

I got that covered too: Just need docking to refuel this guy from a tanker and then dock the PEM to the rear and we\'ll be on our way to Mars

So I thought about this quote: And then I looked at my lander, which comes just short of achieving Kerbin Orbit, and I thought to myself: Challenge accepted So here it is, the uprated version of Planetary Excursion Module, using the good old Kerbal motto of 'MOAR BOOSTERS' now easily capable of achieving Kerbin orbit from KSC. Next test will involve strapping a booster underneath that thing and shooting it up to ohh say 100,000m and then perform a parachute assisted powered descent back to KSC, then once on the ground take off and achieve LKO under the lander\'s own power. If that Planetary Excursion Module can do a landing followed by a take off to Kerbin orbit I say it\'s ready for landing on Mars.

Magical reaction wheels that never need to cancel stored up momentum. http://en.wikipedia.org/wiki/Reaction_wheel

SAS is really only useful for large spacecrafts that need attitude control while thrusters are off. They\'re quite heavy and impose a noticable performance penalty on your boosters. You\'re much better off using that gimballed LV-T45 engine for attitude control on 2nd stage. Strategy I used to use is: (Assuming stage 1 means <20000m, where air is dense enough for fins to work) Stage 1 attitude control - fins attached to stage 1 Stage 2 attitude control - LV-T45 gimballed engines Spacecraft attitude control - Command pod reaction wheel + SAS (if large ship) + RCS (if huge ship and I have RCS fuel to spare for the mission). Nowadays I fire my stage 1 and 2 together in parallel with fuel crossfeed from stage 1 to stage 2, as a result I don\'t even need fins anymore on stage 1 since stage 2\'s gimballed engine will provide enough attitude control for the whole stack before stage 1 separation. You wouldn\'t want to use purely LV-T45 for first stage though because it has poor thrust to weight ratio, LV-T30 or Aerospike with fins is fine but a mixture of LV-T45 with non-gimballed engines with no fins or SAS at take off results in the most efficient rockets.

Yeah I noticed this weird physics while taxing my spaceplane on the ground. What I didn\'t do however is build a single stage to orbit ornithopter, that\'s some impressive machine you\'ve created.

I rewired my lander to be able to drop the parallel boosters in two pairs and then tested it launching from KSC. It nearly managed to make LKO, only something like 80m/s off, less if I used RCS thrusters too. Assuming this 'Mars' planet really does have 0.4G and thin atmosphere the same craft should have no problem making a parachute assisted powered descent and then take off SSTO.

That\'s known to happen with those lakes. My theory is that either the lander\'s engine melted the ice, or Minmus is actually more of a rubble pile than a rigid solid object like Mun, or a mixture of both.

There\'s one thing that\'s been bugging me about lander designs. Namely why did the Apollo LM use two separate engines, one for descent and one for ascent? Seems like a waste of fuel to carry that ascent engine as deadweight down to the lunar surface. In comparison the tiny Soviet LK lander could also carry two people to the lunar surface and then rejoin LOK waiting in lunar orbit. It manages to do this while only weighing 1/3 as much as the Apollo LM by (among other things) using the same engine for both descent and ascent, leaving only its landing legs on the lunar surface. Is there any reason for this particular design for the Apollo LM? It definitely wasn\'t because LM descent engine couldn\'t be restarted because Apollo 13 manage to fire its descent engines multiple times for free return trajectory and course corrections.

Problem with using gravitational assist in this case, other than the small amount of assist the low gravity of Mun and Minmus can provide is launch window. A direct Hohmann transfer orbit to another planet will happen multiple times each Kerbin year. If you had to also get Mun and/or Minmus in position for an assist than the window considerably narrows depending on the length of the Munar month.

If the instability is specifically a tendency for the rocket to roll I know what causes it. It\'s caused by the bottom of your stage 1 and 2 osculating from side to side. If these osculation are synchronized it induces a roll force on the rocket. To fix you have to attach struts right at the very bottom of the outer 9 rockets to the center 3.

It\'s pretty hard due to phantom force from debris, once you grab them they will spin your ship like crazy. Here are pictures from the test I did.

I\'ve been coming up with prototypes of the craft I will need for a manned mission to Planet L 3 vehicles will be launched, one with heavy lifter, one medium lifter and one light lifter. 1. Orbital Tanker / Propellant Deport 2. Interplanetary Maneuvering Stage 3. Planetary Excursion Module IMS and PEM are launched with additional boosters which coupled with their own engine will take them to Low Kerbin Orbit. Once in orbit, the IMS and PEM will dock in turn with the orbital tanker to refill their fuel tanks. the PEM will then dock with the rear docking collar of the IMS. Once hard docked the IMS will fire its main engines for a Hohmann transfer orbit to Planet L. Upon arrival at Planet L, IMS will then turn around for a retro burn to settle down in low orbit above Planet L. The assumption is that Planet L is a Mars like planet - surface gravity 0.4G (Mun is 0.16G), surface atmosphere pressure 0.5% of Kerbin\'s atmosphere pressure at sea level. Parachute only landing is not possible but the rarefied atmosphere and reduced gravity makes it much easier to reach orbit than Kerbin. My PEM when tested on Kerbin can easily reach 60,000m apoapsis after jettisoning parallel stage, so the same craft should have enough fuel for powered descent + return to orbit on a 0.4G planet with almost no atmosphere. PEM undocks from the IMS and make a parachute assisted powered descent to Planet L\'s surface. RCS fuel usage should be minimal since parachute will reduce lateral movements. Once there the Kerbalnauts will get out for EVA, pick up some rocks, plant a flag and whatnot. Once EVA is complete PEM then takes off from the surface, staging once descent/ascent stage is out of fuel and reach orbit to redock with IMS. If things really go pear shaped the IMS\'s own spacecraft stage can undock from the boosters, catch the drifting PEM and bring it back with it\'s own forward docking arm. Once PEM is hard docked IMS then makes another Hohmann transfer orbit burn back to Kerbin with a retroburn in LKO. PEM is filled enough fuel for deorbit burn and deorbits. Then IMS forward spacecraft stage separates from the IMS boosters and makes it\'s own deorbit burn. The IMS boosters are left in LKO. I\'ve sized it with enough tankage that it should be able to attempt a Hohmann transfer orbit to outer gas giant planets so it will be a waste to just let it burn up. With the IMS boosters in orbit a future interplanetary mission only needs to send another PEM, a small control spaceship to dock with IMS booster stage and another orbital tanker to have enough hardware. The orbital tanker fuel tank is also designed to be able to separate with the space tug. Once a tanker is empty the tug can leave the empty tank in space for conversion into a wet workshop space station with the tug itself returns to Kerbin.

I refer to it as 'Planet L' L being after K

Originally I was totally for complete separation of rocket vs jet fuel but after thinking about the problem I had a change of heart. See the best example for this is Skylon and its SABRE air breathing rocket engine. This engine can work both as a ramjet in atmosphere as well as a conventional bipropellant rocket engine using onboard liquid oxygen once there\'s no air. When Reaction Engines Limited or anyone else for that matter go build a spaceplane they\'re not going to go 'hey, let\'s put some jet engines on the plane that use kerosene and then add a rocket engine running on LOX/LH2 for final orbital burn' and end up carrying three different kind of liquid on the plane. They\'re going to get their engines to run off the same fuel plus some oxidizer for the rocket. So with a splaceplane it\'s not a question of 'how much jet fuel vs how much rocket fuel to carry' but rather 'what\'s the ratio between fuel and oxidizer' that the plane will carry given a fixed flight profile. So instead of thinking we\'re adding rocket fuel and jet fuel to our splaceplanes think of as adding just 'tankage' to the plane and the little Kerbal engineers will work out the exact details on the fuel vs oxidizer ratio for that tankage space. It\'s only fair since we have no precise control over this ratio ourselves. Think again:

Hover your mouse over the stage section and use mouse wheel to scroll up and down.

After doing some more research turns out this is quite an old idea: I wonder if we\'ll see http://kerbalspaceprogram.com/forum/index.php?topic=10468.0 for real in the future.

So I was reading Wikipedia pages on boosters to pick up design ideas and came upon this: The first though that came to my mind was 'Hey! They stole my idea!' Okay seriously, how come it\'s taken the aerospace industry so long to use this idea in real life? I started realizing fuel crossfeed was the best thing since sliced bread only a week after playing KSP. Surely this is mature technology by now? Space shuttle\'s been using fuel crossfeed from the External Tank to the Orbiter for 20 years now.

No no, speed and air density are taken into account by the game. If speed wasn\'t taken into account, your plane will be as maneuverable sitting on the runway as it is flying through air If air density wasn\'t taken into account then either: [list type=decimal] [li]control surfaces will continue to work outside of the atmosphere[/li] or [li]there is a sudden point during the ascent where the game treats your plane as having 'entered space' and you instantly lose effect from all your control surfaces[/li] Since neither happen and we do in fact slowly lose use of control surfaces as we climb, it means the game just be taking speed and air density into account.