|
|
Post by nate2010 on Sept 24, 2016 23:37:31 GMT
OK, I've tried this 20+ times and I cant get a mars intercept within the time limit and within my DV reserves. These orbital mechanic missions aren't fun, I just want to get through it. any tips?
|
|
|
|
Post by pokington on Sept 25, 2016 0:09:59 GMT
Use NTRs, not MDPs -- you'll need the thrust.
Take two tankers, ditch one halfway, using it to refuel the other (or design a supertanker with 25+ km/s DV). The extra DV can help.
About a 6 km/s burn from the starting body, if done at the correct ejection angle, gets you very close to Mars within about 12-15 months. You just then have to tweak your trajectory a few months out to pass as close as possible, then do a capture burn very close to the planet.
|
|
|
|
Post by nate2010 on Sept 25, 2016 0:18:18 GMT
well, the stock hydrogen tanker has like 24 km/s DV and an NTR just the only trajectories im getting that even get close to an intercept would require like 100+ km/s to match with the station. clearly im doing something wrong, but this is happening over and over. so two things, how do i set this ejection angle? or can i modify the game files to just let me skip this mission?
|
|
|
|
Post by etranger on Sept 25, 2016 12:03:06 GMT
Seems you need to take it in stages, thus:
1. Burn to get roughly towards Mars
2. Correct the burn en route to try and get into Sol-Mars orbit as close as possible to Mars
3. Burn and inject into Mars orbit.
4. Burn and inject into the Cargo base orbit
5. Burn and merge.
Helps to have ca. 35 kps of dV. Design as big a hydrogen tanker as possible. I'd post the ship I used, but print screen gives the underlying windows level. A "print design" option would be useful.
|
|
|
|
Post by pokington on Sept 25, 2016 12:07:03 GMT
Eject retrograde and slightly anti-radial from Themis orbit (that is, burn prograde when you're pointing the correct direction), approximately 6-6.5 km/s. Basically, wait until you are equal parts ahead of and below Themis with respect to its direction of travel. Do a correction burn a few months out from Mars. Depending on how you did your original ejection this will require a lot of prograde and radial tweaking (probably 1-2 km/s), and at this point you should correct your inclination. You need to pass close enough to Mars to make the "Join LE Cargo Station" icon appear. If you've got a good pass by Mars, the join should really only take a few km/s. I did a quick example here and it was definitely not the most efficient rendezvous I've gotten. I've done it in less than 13.5 km/s, but also notice that my ship has almost 35 km/s of DV (it's a custom hydrogen deuteride tanker) -- if you're just worried about getting it done having a huge DV budget helps. |
|
|
|
Post by bletchleygeek on Sept 25, 2016 12:36:48 GMT
I'd post the ship I used, but print screen gives the underlying windows level. A "print design" option would be useful. I'd suggest using Steam screenshot function - Windows handles windows using OpenGL to render they contents in a special way. |
|
|
|
Post by josephw71 on Sept 25, 2016 15:09:34 GMT
Keep the advice coming, I am really stuck on this one.
|
|
|
|
Post by pokington on Sept 25, 2016 17:35:57 GMT
|
|
|
|
Post by josephw71 on Sept 25, 2016 19:48:46 GMT
Will see if the photos help, will try later to night, could use more info on your ship though. |
|
|
|
Post by pokington on Sept 25, 2016 20:12:56 GMT
It is a silly, silly ship (click me!). It's fully stock parts, so you don't need the module editor to create it. Hydrogen deuteride doesn't block much radiation so you need a lot of shielding. It occurs to me that you could probably shave mass by using a RTG instead of a full-blown reactor, and that might let you size-down the crew compartment.
|
|
|
|
Post by Durandal on Sept 28, 2016 2:25:12 GMT
Okay, Pokington, I've shamelessly copied your tanker design and matched your tragectory as best I can, but I cant seem to catch Mars. On my final approach I keep getting a "gravity overwhelms acceleration" error. Any further tips beyond spelling it out again? :/ Edit: Scratch that, got it in 1 year 3 months at 25.9km/s. I'll take it and run.  |
|
|
|
Post by withcarbos on Sept 28, 2016 20:43:31 GMT
Couldn't for the life of me shape an orbit that looked like yours, pokington. Whenever I tried to intercept Mars at ~1Y3M, I always ended up with absurd dV-reqs just to match orbit. Had to spend 1Y9M, and made it on my 10th try. But that only cost 11.7 kps, so wheee!
|
|
|
|
Post by harlikwin on Oct 2, 2016 16:28:14 GMT
So, I'm also having issues with this. I can "eject" with roughly the trajectory in the first image, but my mars intercept is way less DV (2-3km/s) than the one you have listed and much longer time wise, such that I can't make the time limit. I can't ever get the join station icon, but I can join mars orbit, which is again, a fairly low DV requirement.
I'm using mars as my focus and just using tangential and radial burns to get there.
Is there some advantage to waiting around themis, the orbit there is like 3 months, so I'm basically burning to get out of orbit right away, regardless where it starts me. Should I wait, does the transfer get faster?
I'm also using a pair of hydrogen tankers at this point since I haven't had DV issues yet, I plan on pumping one dry when I hit around 11km/DV so its full when I hit mars.
|
|
|
|
Post by pokington on Oct 2, 2016 17:01:14 GMT
You don't get there faster by waiting, necessarily. You just spend less delta-V by waiting until your orbit around Themis is pointing retrograde and antiradial with respect to Themis' orbit around Sol. If you're willing to spend the fuel, you can end up with a basically identical trajectory at any point around Themis orbit. "Join Mars orbit" means you are putting yourself into an otherwise identical orbit to Mars with a different true anomaly (click me!). It does not mean you are actually close to Mars. You need to tweak your correction burn (the one you do about a month out from your closest approach to Mars) so that you pass even closer to the planet -- that should enable you to either directly join the destination station or to capture into Mars orbit. |
|
|
|
Post by harlikwin on Oct 2, 2016 20:15:02 GMT
Pokington,
Ok that makes sense. In terms of the trajectory though the general consensus is to burn for mars immediately for the shortest time burn?
Yeah, I can't actually get it close enough to ever get an "encounter" with mars so far, even when I'm fairly close. Usually when I try to join the orbit I'm over time...
|
|
