i finally got a chance to fly the final version of the lunar lander of doom, this time with success. my stack. two main lift stages, 14 of the orange tanks each. the upper stage uses gimballed lf engines, while the lower stage some beefy non-gimballed engines from some mod pack. the ring of gimballed lf engines and tanks were added not to produce lift (the unvectored engines provided enough lift force by themselves) but to stabilize the rocket. without them the rocket tends to topple over as its fuel supply depletes. i tried fins but the ship was really hard to control during lift.
running out of fuel with the boosters results in an immediate loss of control, so i tired to pick a tank that when combined with the gimballed engine run out at roughly the same time as the main engines. turns out the standard lf tank was the best for the job, so i used that. they run out slightly after the main engines. you loose some velocity when this happens, but ejecting them with fuel still in them likes to make things blow up (even if throttled back first). i found the loss of velocity to be acceptable. as a result the boosters are ejected with the first stage.
it was also necessary to attach lander legs to the first stage to prevent the engines form being damaged by the rocket's weight. you might also notice the crossbars connecting the engines. this helps stabilize them so that you dont get spin during lift. if you had connected them horizontally any tilt in one engine would pull other engines along with it adding to the problem, crossbars have the opposite effect, so add inherent stability. these exist on the first 2 stages. there are also crossbars holding the center engine in place as well, but you cant see these.
second stage is a much like the first, except using gimballed engines. these are powerful enough to lift the second stage without any help. they also burn for a real long time and can put the ship in orbit with some fuel to spare. so this gets the trans munar injection started. and are ejected when they are depleted. all this connects to the lander with 4 couplers and 3 1-2 couplers, allowing for 7 main engines for both stages. there were also some small radial srbs in there to help kick the second stage away from the first, to help avoid collisions. these trigger when you seperate the stages. you can then light up the second stage.
il spare you the details of the slow as hell tli transit (the joy of ion engines) and get to the good part:
this is the complete upper stage with the ion engine at its core. the ion engines were lit after the 2nd stage was ejected, it still floats around kerbin in a fairly high orbit and should stay there forever. as you can see i only used a little more than half a tank of propellant. it takes a really long time to accelerate enough to raise appokerb to munar orbit, and actually took 2 passes to complete. as a result i missed my intended capture point, so i had to orbit a few times to get capture. when i finally got capture my trajectory intersected mun by a little bit and i had to burn horizontally to miss it before decelerating. im glad i was able to do this with my ion engine and rcs thrusters because i think i had too much velocity to kill with my decent engines and still manage to land.
once again it took the ion engine a really long time to make the orbit circular enough to attempt landing. i lit my decent engine and started in. i periodically used short powerful bursts to keep my velocity down to about 150m/s. when i got close i killed my vertical velocity, and used up the last of my rcs fuel trying to kill my horizontal velocity. after that i killed horizontal velocity by tilting the ship. i had my sas locked to a perfectly vertical orientation, and tilted the ship with wasd untill i was going about 2m/s, i reduced thrust and landed.
i let the kerman boys play a round of kolf (yes, kolf, kerman only ladies forbidden) an packed em all up for the return flight. burned up the liftoff srbs and got a fairly decent apogee on those alone.
i decided against munar orbit and that id just keep following my trajectory (which at the time was pointed in the general direction of kerbin), lined up and hit the throttle. needless to say i had a little too much velocity, but i got capture.
on top of that my instruments were still using mun as their frame of reference, which made reducing this cometary trajectory into something more circular rather tedious. it took me awhile to determine which direction was retrograde. and once i did i burned up the rest of my decent fuel and ejected the engines. my orbit was still fairly large, and comet-like. i wanted to aerobrake but i was concerned i might pass too close to mun and **** up my trajectory. on top of that my instruments were still in the wrong frame of reference so i used my ion engine to to drop apogee to safely inside mun's orbit (this took a long time).
as i passed kerbin i noticed my readings were correct again. so i killed the engine and waited for apokerb. once there i locked the sas at retrograde and fired the ion engine. i switched to the orbital view and watched the altitude at perikerb, and waited for it to get between 40k and 50k, and killed the engine. and it worked, after 2 passes my orbit started to look more circular. so next time at apokerb i dropped my perikerb to 38k and waited. and when i came around and watched my orbit decay, knowing i was going in this time, i dropped the ion engine. shortly later i made a nice water landing.
shortly after landing jeb was arrested by the krs for not filing his tax return on time.
also unlike herra i halved the res and converted to jpeg, so 56kers and my ****ty 0.5 megabit connection can load the pics in a timely manor.