the long orbit

[scotty110]

So I built a rocket, command module stage include decoupler, Advanced SAS, RCS fuel tank (4 symmetry RCS thrusters) 2 liquid fuel tanks, a half liquid fuel tank and the vectored liquid engine. second stage was 8 liquid fuel stacks with 4 tanks each and the nonvectored liquid engines as well as 8 solid rocket boosters and winglets (the pivoting ones), I made sure to use struts to hold the liquid tanks together.

After a shaky liftoff I get into a comfortable 100km orbit around Kerbin with about 1/4 fuel in the last set of second stage tanks which i use to get a boost towards the Mun. I end up using the half tank of my command stage to get into Munar orbit because I just about missed it completely. I still had 2 full tanks of fuel so I orbit Mun a couple times before making a return attempt, the first attempt I burned too soon and it would have sent the capsule way off from Kerbin so I retroburn to fix my orbit around Mun and wait for another opportunity. Next time around I burned later and it looked like I might make it to Kerbin so I speed time up and wait. Once I got far enough away from Mun, my orbit shifted to around Kerbin....with a Periapsis of 9.8 million meters and a Apoapsis of 22.9 million meters....

Alright, at this point I still got a little over 1 and a half tanks of fuel left, so I figure I\'ll do a spiraling orbit by retroburning at each Periapsis to shrink the Apoapsis. my Kerbonauts have already been in space for about 1 day MET and it takes about a day and a half MET to shrink my orbit around Kerbin. I get my Apoapsis to 150k and my periapsis to 100k when ::dun dun dunnnnnnnn:: my liquid fuel runs out, Ok no biggie, I still have a little over half a tank of RCS fuel, I can use that to shrink the orbit some more... so I retroburn on that until it runs out, and I get a periapsis of just under 57k, now the waiting game began.

When I reached the Periapsis I was a little sad when my parachute didn\'t deploy and my capsule started gaining altitude again, however that was cancelled out when I noticed that my Apoapsis had shrunk from 150K to about 138K so I figured I might as well see what happens, sure enough as my capsule approached the Periapsis again, not only did it the Apoapsis shrink another 20K, but the Periapsis shrank by about 1k, each subsequent orbit continued to decay until finally after 4 days and 7 hours in space, the parachute finally deployed and my Kerbonauts splashed down safely.

Anyone else got any similar experiences of barely making it home after a mission?

[khyron42]

You\'re doing the exact opposite of what you want to do on a return trip - you want to slow down at Ap to bring your Pe down to about 30 km, then ta-da! single orbit return.

I have done a long return where the Ap was still up around 6000 km and the Pe was 50 km when I accidentally hit space bar instead of throttle, which took forever to gradually bleed off the excess speed over a dozen orbits. I\'ve also ended up on a non-return orbit (10000 km x 1000 km) that re-entered the Mun\'s SoI hundreds of days later, and through sheer luck the gravity-assist ended up putting me on a very direct return orbit.

[maltesh]

Indeed. If you don\'t leave Kerbin\'s SOI, and the Mun doesn\'t interfere, the maximum delta-V needed to deorbit from an elliptical orbit is about 450 m/s.

The second time I attempted to leave Kerbin\'s sphere of influence, orbit Kerbol at least once, and return to Kerbin, it took over 2200 days for me to guide the spacecraft back into Kerbin\'s SOI. By about a factor of three, that was the longest mission I\'ve ever flown that successfully returned to Kerbin.

My bi-elliptic sundives typically are about 1200-day trips, which is much, much longer than the direct route, but far less expensive in fuel.

[scotty110]

thanks for the tips, I\'ll keep that in mind next time.

[sal_vager]

rather than start telling you what you should be doing, I\'ll tell you about a flight I did yesterday...

I was trying out the Failcan 3, a very wobbly rocket, and I hit the tower on launching, something exploded but I couldn\'t see what.

I thought about aborting but the rocket was flying fine, and I looked through the sidebar but couldn\'t see what was missing, so I carried on.

I reached orbit, jettisoned the launcher stage and boosted my Ap to 150km, as I was going to drop off the Durgun\'s service module as a kind of satellite, when my Pe was 20k I dropped the upper stage and tried to fire the Durgun\'s mini engines.

Now I found out what blew up all the way back at the launchpad, I had 3 of 4 engines and it was impossible to maintain my heading with the off axis thrust, I was reduced to RCS only.

I pressed on, Kerbin would have it\'s satellite, and limped slowly into a circular orbit, once there I unfolded the service modules solar panels, detached, and moved clear with gentle puffs of compressed air.

Now to return in an unfamiliar craft with an unknown amount of RCS, I lowered my Pe to 35k and hoped for the best.

Returning to Kerbin I passed over the ocean only to find myself with the possibility of a hard landing with no engine to cushion the blow, RCS was not strong enough to lift me so all I could do was watch and wait.

Thankfully the hard unforgiving land turned into islets passing below, and I came down in a small bay, just tens of meters from a sandy beach, RCS on full just in case the chutes didn\'t slow me enough.

Safely down, and with the sun just beginning to set, I ended the mission, it\'s always the most fun when things seem to go wrong but you still pull through

[Trekky0623]

You\'re doing the exact opposite of what you want to do on a return trip - you want to slow down at Ap to bring your Pe down to about 30 km, then ta-da! single orbit return.

I have done a long return where the Ap was still up around 6000 km and the Pe was 50 km when I accidentally hit space bar instead of throttle, which took forever to gradually bleed off the excess speed over a dozen orbits. I\'ve also ended up on a non-return orbit (10000 km x 1000 km) that re-entered the Mun\'s SoI hundreds of days later, and through sheer luck the gravity-assist ended up putting me on a very direct return orbit.

Well, if his AP was too high, he\'d be going at a monstrous speed by the time he hit Pe. Don\'t want to burn up in the atmosphere.

[UmbralRaptor]

Well, if his AP was too high, he\'d be going at a monstrous speed by the time he hit Pe. Don\'t want to burn up in the atmosphere.

Unless he has a hyperbolic orbit, it\'ll be below 3400 m/s. I would be hesitant to call that monstrous.