Author Topic: Kerbal Space Program or "Rocket science is harder than it looks"  (Read 278705 times)

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Offline Herra Tohtori

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
Breaking   news!
Mün   is   radioactive!


Based on the analysis of the samples collected near
the landing zone on the recent Mün landing mission -
the Mün is highly radioactive!



Scientists have found significant quantities of high and medium active isotopes from the samples
recently brought back from the first successful Mün landing with enough leg room to fit in some
scientific devices and haul back samples. The sensational results need to be confirmed by peer
reviewed analysis of the tests, but preliminary inspection of the samples is conclusive with fissile
products.

-The isotopes we found have very short to medium half lifes, says Kerbal Space Program leading
geologist Bobby Bartholomew "Dread Bore" Kerman. -We do not yet have clear picture of the
distribution mechanism of these isotopes, but it does mean that there have been nuclear activity
in the Mün during recent years, possibly even months.

The most vocal supporters of the "Mother Kerbin" theory of the Mün's origin have already hailed this
discovery as a confirmation to the hypothesis that the Mün was separated from Protokerbin in a
massive impact hundreds of years ago. In their opinion, these fissile product isotopes suggest that
the Mün, like Kerbin, contains a high mass percentage of transuranium elements - to an extent where
spontaneous fission is possible.

-There must be a reason for all them craters and holes, and fission reactions undergoing under
the surface of the Mün would certainly explain them, said the chairman of the Society for Promotion
of Mother Kerbin Origin of The Mün, Lawson Carson Anderson "Son" Kermanson. -I mean, sure, some
say that Mün was probably just hit by some Useless Bits of Rock, but come on, seriously, Useless Bits
of Rocks are out there and the Mün is here, clearly there's a miscommunication here.

Meanwhile, the three Kerbonauts, Bill, Bob and Jebediah Kerman, are still in extended quarantine to
make sure they have not been exposed to higher than usual levels of radiation from the Munar dust
carried into their ship during their Munar excursions. So far, all appear to be in excellent health.

In a statement earlier today, the flight crew briefly commented the flight.

-It was eerie, almost everything went smoothly, told the flight's commander, Jebediah "Jeb" Kerman.
Other crew members - William "Bill" and Robert "Bob" Kerman - agree.
-Yeah, aside from that little hijink on the way back, everything went better than exepected, William
Kerman told us. Robert Kerman shed some more light to the brief period when communications were
lost to the crew: -Well we lost communications and then things went a bit weird. I never thought I'd
see a Resonance Cascade, let alone create one, but I guess that's what happened, our displays were
alternating between different orbits and we seemed to be stuck on the neutral gravity area between
Kerbin and Mün, but Jeb - that's Jebediah - he just put the engine on for some time and the problem
went away.

The plans for positioning a satellite on a Lagrange point have been postponed in the light of this
unprecedented risk, until the behaviour of neutral gravity areas are understood better.


---

On other news, Kerbal Space Center has announced a minor design change in the famed Munlander Mk.II
design, in which the lander's extremely efficient fission engine will be replaced by a suitable replacement.
Technical director of the Munlander programme was not available for comment.
« Last Edit: November 05, 2011, 05:56:48 am by Herra Tohtori »
There are three things that last forever: Abort, Retry, Fail - and the greatest of these is Fail.

 

Offline watsisname

Re: Kerbal Space Program or "Rocket science is harder than it looks"
Simply amazing.  I was most certain they would not return safely after that trans-Kerbin resonance cascade, as I shall call it.  Awesome that you got them back and in one piece. :D

Now I want to see atmospheric reentry get updated a bit, with reentry flames! :O
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Offline Herra Tohtori

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
trans-Kerbin resonance cascade


I hope you don't mind that I borrowed that a bit?  :p
There are three things that last forever: Abort, Retry, Fail - and the greatest of these is Fail.

 

Offline Commander Zane

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
I've never seen those legs before, which pack is that from?

 

Offline Bob-san

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
I've never seen those legs before, which pack is that from?
You should just use the game's stock legs.
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Offline Commander Zane

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
Ah hur hur hur. :doubt:

I just realized they're CaptainSlug's lander legs so nevermind.

 

Offline TwentyPercentCooler

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
Herra, do you work for a space agency?

If not, you should.  :lol:

 

Offline Nuke

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
my attempt at a lunar lander:

i grossly underestimated the amount of fuel id need for my descent stage so i had to abort. in firing the 3 mini-srbs (these would have been my liftoff engines), i discovered that one of the engines was damaged during launch and did a spinout into the mun's surface, killing the crew.

i actually like the design of the craft. at its core is an ion engine, which carries enough propellant to get to mun and back and then some. this stage is started first but is not ejected until after the de-orbit burn into kerbin's atmosphere. the next stage is the decent engine. the 6 yellow tanks provide some fuel (this was not enough and so these were replaced by 3 standard lf tanks in later models). the ion engine is used in tandem with these (because you cant turn it off once its started), but considering the slow rate of burn the loss is negligible.

right now the lander legs are attached to the decent engines, providing a wide stance for stability. the idea was i would eject the decent stage after liftoff with the srbs, but it is likely there will be fuel left in them at launch. i might just have it set up so i can throttle back the engines and use them for orbital maneuvering later on and just light the srbs for the initial liftoff without ejecting anything. it would be beneficial to attach the lander legs to the srbs then, since they will be ejected first. once exhausted the engines and legs would be jettisoned and the decent engine throttled up. otherwise the decent stage (with legs) would be depleted and ejected first, and the srbs would be used as a second stage. i may even consider the complete removal of the mini-srbs, given their unreliability thus far i might be better without them.

regardless the ion engine will provide transit back to kerbin from munar orbit. since mun only orbits at some ~500m/s, i might consider lifting off from mun (quasi)parallel to its orbital trajectory in the retrograde direction, and use kerbin's gravity to fall to the planet. perhaps i will attempt an aerobreak maneuver to speed my return voyage.  i seriously need to update all my mod packs though, many of them are really old and dont take advantage of the new features.
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Offline Nuke

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
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.
« Last Edit: November 05, 2011, 06:26:54 pm by Nuke »
I can no longer sit back and allow communist infiltration, communist indoctrination, communist subversion, and the international communist conspiracy to sap and impurify all of our precious bodily fluids.

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Offline Bob-san

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
I reached Munar orbit but I had that rails problem and it tossed me towards the sun at some 9 km/s.
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Offline Commander Zane

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
Yeah I've gotten that too. My orbit intersected with Kerbin in two spaced-out points but 10,000x compression is far too slow to try waiting to meet back up with Kerbin in such a scenario so I had to stop.

 

Offline Nuke

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
I reached Munar orbit but I had that rails problem and it tossed me towards the sun at some 9 km/s.

accidental gravity assist for the win!
thats why i like ion engines, the margin for error is so much greater and you only need one small fuel tank. aerobreaking can save fuel too but you can only really do it on your return to kerbin. a tiny bit of thrust at apokerb can save you lot of fuel where you would have waited and done a long burn at perikerb. just remember that if you want to stay in your orbit you need to lift perikerb out of the atmosphere or it will continue to decay at each pass.

i think it would be kinda cool to have more moons though. perhaps small ones like phobos or moons with atmosphere like titan, to let you play with maneuvers like gravity assist and aerobraking in a more useful manor.
I can no longer sit back and allow communist infiltration, communist indoctrination, communist subversion, and the international communist conspiracy to sap and impurify all of our precious bodily fluids.

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Offline Bob-san

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
I reached Munar orbit but I had that rails problem and it tossed me towards the sun at some 9 km/s.

accidental gravity assist for the win!
thats why i like ion engines, the margin for error is so much greater and you only need one small fuel tank. aerobreaking can save fuel too but you can only really do it on your return to kerbin. a tiny bit of thrust at apokerb can save you lot of fuel where you would have waited and done a long burn at perikerb. just remember that if you want to stay in your orbit you need to lift perikerb out of the atmosphere or it will continue to decay at each pass.

i think it would be kinda cool to have more moons though. perhaps small ones like phobos or moons with atmosphere like titan, to let you play with maneuvers like gravity assist and aerobraking in a more useful manor.
That wasn't a gravity assist though--that was pure madness! It's also pure annoyance. That said, I know there's a relatively quick way to figure out how to do a 2-body orbital transfer. The tough thing is, while I used a really overpowered rocket (seriously overpowered--designed to reach the Mün with only stock parts), performance is so poor I can't keep a flat orbit with any reliability. Seems like any control surfaces or RCS is ignored.
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Offline Nuke

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
i dont think landing on mun with stock hardware is possible. there are no lander legs for example. there are no light engines/tanks needed for the return trip. that little ion powered lunar lander i built can do the complete round trip from low kerbin orbit and back. id like to be able to pull off the voyage with non-modded parts but im not sure how to pull it off just yet.
I can no longer sit back and allow communist infiltration, communist indoctrination, communist subversion, and the international communist conspiracy to sap and impurify all of our precious bodily fluids.

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Offline Herra Tohtori

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
i dont think landing on mun with stock hardware is possible. there are no lander legs for example. there are no light engines/tanks needed for the return trip.

People have done that many times. Don't know if any have returned successfully but I think it's likely.
There are three things that last forever: Abort, Retry, Fail - and the greatest of these is Fail.

 

Offline Nuke

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
im not saying its impossible but it would be really hard to pull off. im pretty sure one tank could get you to mun if you stick with hohmann transfers. you could probably land on an engine, but it could blow up if it hits too hard, and if you pulled it of you might break it in the process, and im not sure you would have the fuel. so you'd need a second tank and engine for the return trip.

one thing i noticed is that the rcs engines are fairly powerful. one tank with 16 rcs quads and a capsule can take off from kerbin and fly around for abit. 3 rcs tanks and 16 quads should handal munar operations jsut fine, and you can land on the fuel tank at low speed. it might be workable to land on a stack decoupler, and this can be ejected at liftoff to save weight. i figure you could get close to the ground and eliminate most of your velocity with a lf engine, and drop it with a second decoupler, leaving one to land on. liftoff would be done with the rcs quads and your best bet would be to burn in the opposite direction to mun's velocity vector (you only need about 500m/s of delta v for this, not counting liftoff and orbit), and allow yourself to fall towards kerbin, and then end with an aerobreak maneuver.
I can no longer sit back and allow communist infiltration, communist indoctrination, communist subversion, and the international communist conspiracy to sap and impurify all of our precious bodily fluids.

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Offline Commander Zane

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
As far as stock goes I've seen radial decouplers used as part of the landing legs. I don't know how reliable that is though.

 

Offline Rodo

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
With stock hardhare.. you kiddin'? I had a terrible time trying to get something into orbit with just stock hard.
Pulled it off eventually but run out of juice half way to the mun... oh man they never returned :C
el hombre vicio...

 

Offline Herra Tohtori

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
There are three things that last forever: Abort, Retry, Fail - and the greatest of these is Fail.

 

Offline Bob-san

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Re: Kerbal Space Program or "Rocket science is harder than it looks"
With stock hardhare.. you kiddin'? I had a terrible time trying to get something into orbit with just stock hard.
Pulled it off eventually but run out of juice half way to the mun... oh man they never returned :C
I've seen a screenshot of it being done. I'm going to give it a try later. Anyone know if X3 fixed the omfgravityassist bug?
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