Thoughts: Rescue Mission on Mun

[MrOsterman]

I have successfully put Sila Kerman as the first kerbal on the Mun.

Unfortunately we came in hot and and at an angle and her pod crashed destroying the fuel and engines and leaving only her capsule and science arts undamaged. So she's stuck there.

I'll also admit my track record for Munar landings is spotty but I'm struggling with the save game features to save my game while enroute to the mun and then restoring a save. I did one where I purposefully called the game "Moon Shot" and when I went to reload it later it was gone with just a list of "Quick Save ##" there. So I know I have a hard time nailing a good landing still (though I did put a probe down on Minus very neatly.)

I know part of it has been ineffiecent rocket design. I just got Heavier rocketry, and I don't have the 3 kerbal command capsule yet. I was trying to do something with the Rockamax fuel tanks as my Lift stage, a combination of 4 Swivel engines as my orbit and moon shot stage, and then a Terrier as my Munar orbit, descent and return stage. I had one game where I landed at an angle, and was able to use the doors of the Materials bay to push the pod mostly upright and then blast off the surface but I wasn't able to save enough fuel to get a return flight set up; she'd be lost in a permenant orbit with that plan.

My current thinking is to try copying one of the other builds I've seen but top it with an advanced probe unit and send it unmanned. Basically have the probe send her a life boat to get on and then come home. Should that be workable?

[MaxwellsDemon]

Sounds good.

I had a situation earlier in my current campaign where a lander was wrecked when trying to shift position, and then the ship I sent to rescue them had a hard landing that wrecked the main engine bell, stranding THAT crew as well... a third and re-designed lander was required. (I left the wreckage in place as a memorial to the event, though all Kerbals did get home safely.)

[monophonic]

Yes, that should be workable. Compared to a manned rescue mission there's also that if you crash the rescue lander, you still have just one kerbal to rescue. Some might consider that a disadvantage but you seem like a person who would disagree with them.

Also you may find meeting up on orbit easier than precision landing next to a crash site. I know I do. That wont help Sila of course, but could have worked in that previous game. Reason being that on orbit, if you don't get it right, you just keep going around and try to improve on the next near pass. Landing attempts are a do-or-don't type of choice. Even if you don't crash the rescue ship it doesn't help if you ended up half way to the other side from the one needing rescuing.

[Miro Beero]

I've been playing since .18 and I didn't even know there are multiple saves.

I crash em, I go rescue em.

[eddiew]

Named saves mess up if you hit the enter key instead of the ok button. Might be the source of your pain

F5 and F9 are, otherwise, your best bets (quicksave/quickload) - but if you quickload, you'll lose the ability to revert to launch, so I'd recommend making a named save while everything's still in the VAB.

[MrOsterman]

Named saves mess up if you hit the enter key instead of the ok button. Might be the source of your pain

F5 and F9 are, otherwise, your best bets (quicksave/quickload) - but if you quickload, you'll lose the ability to revert to launch, so I'd recommend making a named save while everything's still in the VAB.

How is that still a bug at this point?!?

Okay well now I know where those saved games went. I don't mind losing my revert option. I felt really good about my chances on that landing until I, ya know, lost control of the landing itself. Or I would have liked a chance to replay the assisted flip launch to see if I could get a better take off once the rocket was upright (I think I still had it stuck "retrograde" or something stupid like that at first so I wasted a lot of my precious fuel on take off).

Maybe I should have tried to use Sila's RCS thrusters to push the module back to an upright state for take off...

Meh. Mostly I just don't want to have to replay launch into orbit if I don't have to... that and I'd like to actually hit Munar orbit without having to stop on the way there. I always seem to struggle getting the manuver point right and end up passing in front of the mun, then being pulled back towards it's orbit as opposed to coming up behind it and into orbit that way.....

[Captain Vlad]

Not sure how useful this advice will be, but I used to have all sorts of trouble with Mun landings until I started designing my rockets so that the stage that gets me to the Mun also has enough gas to orbit and do at least part of the landing. That preserves the landing stage's fuel supply for launch, re-orbit and return (or launch and direct ascent to escape, whichever you use).

And if you're having trouble sticking your landings, try a wider landing leg footprint, if you've got the parts to do it. It did wonders for me.

I've done the unmanned lifeboat thing before myself, after I screwed up a contract mission's landing and stranded both him and the guy I went to get. It's become my favored rescue method.

[lost_in_space]

How is that still a bug at this point?!?

Okay well now I know where those saved games went.

Exactly.

The enter key should perform the same function as hitting the OK button. This is a pretty significant UI mistake.

Bottom line is, if you don't see the "quicksave" message at the bottom right, it didn't take.

[MrOsterman]

Well I'm off for the weekend of packing my earthly mother in law and won't be on Kerbal so I won't be able to report success.

I will report continued lack of it though. Seems I always am short of fuel for the burn to the moon and then getting into a Munar orbit. Do you guys overshoot and then coast in (which feels like a very very small window to hit) or undershoot and then get pulled in close to it as you slow more?

So far I'm trying an extra fuel tank or so but it seems that the weight of the tank outweighs the added time burning leaving me still with the same result: I'm burning half of my lift stage's fuel trying to park (which I seem to be coming in WAY too hot WAY too often). Maybe I'm taking the "burn horizontal to kill your lateral motion then manage your drop" too literally. Seems that I burn a lot of fuel slowing down on one vector and then shifting to another vector rather than just burning purely retrograde.

Grumble Grumble. I oughta just leave her there....

[lost_in_space]

Seems I always am short of fuel for the burn to the moon and then getting into a Munar orbit. Do you guys overshoot and then coast in (which feels like a very very small window to hit) or undershoot and then get pulled in close to it as you slow more?

I never overshoot, except on purpose. You should be able to control this.

Here is what I do:

1. Take off from KSP, angling east to get into a prograde kerbin orbin, lining up as close to the equator as possible.

2. Make a maneuver node so that you reach the mun's orbit, making sure the Mun Encounter occurs before crossing the Mun's orbital path. If you cross that line, you will get into a retrograde Munar orbit. To setup this maneuver node, fiddle with the icon by grabbing the white circle and pulling it around your current kerbin orbit path. Did you know you could do this? By adjusting the white circle and playing with prograde/retrograde, you should be able to setup a decent Mun encounter. It doesn't matter if the encounter occurs in front of, or behind, the Mun, as long as you don't cross the Mun's orbital line.

3. Fast forward to the mun encounter.

4. When you get your Munar vector line, setup a maneuver point to orbit the Mun by retrograding (slowing down). I set this point up in the middle of the line, at the Ap point. After executing this, you should have a decent prograde orbit around the Mun.

5. Retrograde accordingly to get down to 100K orbit.

6. Setup a maneuver node, retrograding to the spot desired on the Mun. I try to pick a spot clear of craters. I don't come straight down, but at a bit of an angle. The more angle you use, the more inaccurate your landing spot will be.

7. Hit the maneuver node and come down. With the weight of my ship, I fire my engines at 25K to slow down. I am pointing directly retrograde.

8. Nearing the surface, 3 of my fuel tanks inevitably run out, and I have to jettison them. This causes my ship to move a bit in another direction, so i have to use RCS to stabilize. I also have to take SAS off of retrograde and put it on stability assist, otherwise I'll be pointed at a bad angle.

9. Land. Sounds simple, but often isn't. Use RCS to stop moving laterally. Avoid craters. I use radiators, besides landing struts, for additional stabilization in case I land on an angled surface.

This is what I do when I want to land on the Mun and do research, plant a flag, etc. I would not do this if trying to rescue someone. In my experience, it's too frustrating to try to hit that exact point on the mun without wasting a ton of fuel, inevitably not having enough to get back.

Therefore, I use what I call a "space buggy". It is a ship that can also fly like a plane. It is a normal looking rocket with capsule/180 fuel tank/360 fuel tank/terrier engine. It has 6 LY-01 landing gears on the "underside" so it can take off and land like a plane. It also has 4 vernor engines on the underside that ease landing, along with the usual 2 sets of RCS on the 4 axis (top/bottom).

I have a fuel depot orbiting the Mun. The space buggy is docked to the depot. Whenever I need to rescue someone on the surface, or perform temp/pressure scans on the surface, I send the buggy out. I can see the markers and a target far more easily with this ship than I could with a normal "upright" ship.

I perform the tasks, and have enough fuel to make orbit again and rendezvous with the depot. After achieving Munar orbit, it is surprisingly easy to use only RCS to link back up with the depot.

I had a crash on the Mun, stranding a kerbal, and spent two week trying to design the right ship to get him. I eventually used my original design, detailed above. I left the kerbal at the depot, in case I need to perform EVAs for future Munar missions.

Conclusion: I believe you can perform your rescue with one ship, but it's going to be very frustrating. And the further they are from the equator, the worse it will be. Good luck!

[MrOsterman]

Thanks! I'll be working on it tonight and seeing if i can finally make use of my RCS thrusters for more than must changing pitch (I just discovered "Translations"). I'll see if that can get me through...

[Tourist]

Not sure if this is the problem or not, but the coming in too hot and at an angle reminded me of a problem I had with landing once. Long story short, no matter what I did, I had to much lateral velocity... thus, I came in too fast and at a bad angle. I thought it was a design issue. Ie engines to powerful, too much/too little gimble.

Long story short, the speed indicator was not clicking over automatically from orbit to surface. Which meant when I thought I was killing velocity, I was actually adding velocity. Just a thought, and a thing to look out for.

[Venusgate]

Consider not sending up a second set of science parts for the rescue. you can still perform the science and collect all the data, then hop in your rescue command pod and be on your way, leaving the empty used science parts behind. should save you some weight, i.e. dV

[Geschosskopf]

[quote name='MrOsterman']My current thinking is to try copying one of the other builds I've seen but top it with an advanced probe unit and send it unmanned. Basically have the probe send her a life boat to get on and then come home. Should that be workable?[/QUOTE]

Nuke the site from orbit. It's the only way to be sure :D.

Seriously, though, either send a mutli-seat pod with an empty seat for Sila to ride home in, or put on a probe core that can do SAS (the OKTO is the 1st available that has this feature), and send the rescue ship out with zero Kerbals aboard.

[Wanderfound]

1) For a KSC-Mun return mission with a fair margin for manoeuvre and inefficiency, plan on about 9,000m/s ΔV. If you don't know how to figure out ΔV, Kerbal Engineer is one of several mods that will do it for you. If you don't like mods, it is possible to work out ΔV with some not-too-hard mathematics, but that's rather tedious to do.


2) Set up your approach before you get there. When you're about halfway between Kerbin and the Mun, switch to map view and double-click on the Mun to focus your view there. You should be able to see your incoming trajectory. Lock the SAS to prograde, wait for your ship to stabilise then activate RCS and experiment with very brief taps on the translation controls. Quicksave before you do this.

At this range, you can make adjustments to your inclination and periapsis for tiny amounts of ΔV. Set it up so that you're coming in on the inclination you want, with a periapsis of 10km (the highest Mun mountain is about 8km).

An approach that puts you in front of the Mun (so that the Mun's gravity is pulling you retrograde relative to Kerbin) is a bit more efficient than one where you come in behind the Mun, but it's not a huge difference. Also, a Munar prograde (i.e. west-to-east) orbit is more efficient for landing than Munar retrograde. So, ideally, you want to come in from in front of the Mun, but on the Kerbin-facing side.


3) For the landing, aim to bring your ship to a dead stop a few hundred metres off the surface, then vertically drop the last bit. As you get more comfortable that few hundred metres can turn into a few dozen, but better to have some buffer to start with.

Begin by aiming surface retrograde, but then pitch above retrograde to control your vertical speed as you scrub off the horizontal velocity. Mods such as Kerbal Engineer that provide separate lateral and vertical speed indicators make this easier; so do visualisation aids like Kerbal Flight Indicators. But, in a pinch, just keep an eye on the VSI at the top of the screen next to the altitude readout.

Watch your lateral velocity during the final descent, and either angle the main thruster or use translation RCS to keep it zeroed. Aim for a touchdown speed of no more than a couple of m/s; the slower the better. Keep your hands on the controls after touchdown so that you can lift off again if the ship begins to tip.

[GoSlash27]

MrOsterman,
A Mun rescue vessel doesn't require much when designed properly, but you're new at this so we just have to accept that.
Your plan is sound, but there's one important thing to remember:
You have a specific place you need to land. Landing in a precise location is hugely wasteful of DV compared to simply landing.
[U][B] Therefore you must design your descent stage to have twice the recommended DV.[/B][/U]

1,200 m/sec from Munar orbit to the surface will give you enough leeway to land right on top of her.
If this requirement proves insurmountable getting her home, just design something that will get her to orbit. Rescuing somebody from munar orbit is much easier than rescuing them from the surface.

Spare no expense and get her home safe!
-Slashy

[tranenturm]

The biggest help I had in landing was when I learned to use the retrograde SAS. Simplifies things immensely.

Line up your landing site and come in fairly shallow. Flip to retrograde and when you're getting close, hit the jets to burn retro until you cancel most of your velocity. The big danger is zeroing out and heading up which will cause your retrograde to switch flipping you over. So long as you don't do that, just get to about 5 m/s and keep it there until landing using the fine point engine control. The retrograde SAS will cancel out your horizontal movement. Knowing you landing altitude will help conserve fuel so you can hit the jets later than when you don't know the hard deck.

So long as the landing site is flat enough it's really easy. If you're landing on a slope, it's all up to how top heavy your ship is.

[MrOsterman]

Well an update:

She's still on Mun. She's delightfully chipper about it, but she's started looking for some potatoes to, as she said, "Science the F out of".

It may be time to start to use some mods to help me get this laid out right as my current plans seem to have me orbiting the mun at too fast with only a single tank of fuel for the descent and corresponding ascent stage. Fortunately she's on a fairly flat area, and along the equator line. I've been hesitant to pack too much fuel for the lander (I've seen some designs using three fuel pods off the main pod as a kind of tripod build). But I think I do have to rethink this all because I'm pushing too much mass into orbit and then into the munar orbit and that's gotta be part of the problem.

I'll work more tonight....

[problemecium]

Mk1 lander can + FL-T200 + 24-77 "Spark" = simple foundation for Mun lander.
I've been using this basic recipe for over a year now and in all the versions that have been coming out, even with the engine adjustments, and it continues to work like a charm. You'll of course want to add landing gear, solar panels, etc. as necessary. ;)
P.S. For rescues you'll of course want to wedge a probe core in there somewhere.

[MrOsterman]

[quote name='parameciumkid']Mk1 lander can + FL-T200 + 24-77 "Spark" = simple foundation for Mun lander.
I've been using this basic recipe for over a year now and in all the versions that have been coming out, even with the engine adjustments, and it continues to work like a charm. You'll of course want to add landing gear, solar panels, etc. as necessary. ;)
P.S. For rescues you'll of course want to wedge a probe core in there somewhere.[/QUOTE]

Wait, how's the Lander Can do with re-entry into Kerbal atmosphere? I got the impression from it that it was a sure fire shred on re-entry.

My build for a lander has been:
Parachute
Probe-core
MK1 Capsule
Materials Bay
Heatshield
Fuel Tank FL T200
Terrier Engine (the smallest I have currently unlocked for the 1.25m body type.

My problem seems be that I start burning fuel for the Terrier in while still coming around the mun pretty fast. By the time I set down I'm only at 20 fuel units left for it and I have bad feeling that won't get me home unless I'm danged lucky. I've been trying to keep the materials bay because, oddly, I found that I can use the doors to toss my capsule back up right if I land and fall over. Maybe I should experiment more with the RCS thrusters to do things like slow/ manuever/ land rather than the main engine....

[Waxing_Kibbous]

I would build a decent lander that has about 3500dV with science gear for the rescue so that you can pick her up, hop to another biome or two for more science to make the trip worthwhile, and swoop on home. Have a capsule with a pilot and the lander can with heat shield at the bottom. Don't be cheap about getting it there, you'll spend more doing it twice. Overbuild the rescue rocket so you can orbit the Mun with the second stage, even slow down a bit with it on decent if you are lucky. Then your lander will have plenty of fuel for the rest of the matters.

I found that having a one star pilot helps a ton for landings, make them point at retrograde in surface mode so you can focus on the speed end of it. They will control it quite well so you get a nice straight down trajectory. Edited November 16, 2015 by Waxing_Kibbous

[MrOsterman]

I am happy to report that Sila Kerman is back on Kerbal all safe and sound and with a pile of science to show for it. I ended up building a lander using the "core engine and 3 outrigger engines." Taking off was an adventure and got lucky with a fluke launch at 45 degrees that put me on a direct shot back to Kerbal.

Thanks all!!

[JAFO]

[quote name='eddiew']Named saves mess up if you hit the enter key instead of the ok button. Might be the source of your pain :)

F5 and F9 are, otherwise, your best bets (quicksave/quickload) - but if you quickload, you'll lose the ability to revert to launch, so I'd recommend making a named save while everything's still in the VAB.[/QUOTE]

I cannot believe nobody thought to mention the joys of named quicksaves.. (Alt-F5 & Alt-F9)