Need some advice getting back from LKO...

[Fearless Son]

Okay, so as I mentioned in the "What Did You Do In KSP Today" thread, I started a new career recently after the 1.1 patch dropped.  However, I find myself in a bit of a conundrum, and I hope I can get some advice from other experienced players.  

So, like you do in a new career, I took some contracts to rescue stranded Kerbals in Low Kerbin Orbit, both for the funds and to build my roster.  I designed a small craft big enough for a pilot and two passengers, sent up Jeb to rescue one, and he brought the stranded Kerbal back with no trouble.  Craft worked great.  So I got two more contracts for rescuing Kerbals, both also in LKO.  I sent up the same craft with Valentina at the helm this time, because Jeb already had one star in his piloting skill and I felt that Val could use the experience, and since I knew the craft was solid, I figured this was an easy run.  So Val went up and performed two separate rendezvous in the same flight, successfully getting Nana and Katly onboard.  Yay!  Okay, time to return to the surface.

... and that is where things got complicated.  

You see, the craft is built with low-tech parts and no heat shielding.  Now, if it can keep its engine pointed retrograde during the descent, it will be fine.  The engine can take the heat, and if it starts overheating I can burn fuel to transfer heat outside and slow down further at the same time.  But my last flight had two advantages over this one: Jeb had one star and could keep the craft pointed retrograde through SAS, and since it only made one rendezvous it had more fuel left to burn during descent.  While Val can keep a craft relatively steady, she cannot keep it pointed retrograde, introducing the possibility that incidental forces might push it into an unrecoverable turn (which leads to rapid and fatal overheating at the airspeeds involved) given the relatively weak electric torque forces provided by the command capsule.  While I had to burn some fuel on the descent previously to help give the pilot more ability to fight those incidental forces and slow the craft at the same time, I have much less of it now, not enough to burn willy-nilly and finding just the right moment to light the engines and with just what amount of throttle has been troubling to me. 

Here is a picture of my craft.  It has two radial drogue chutes, two radial regular chutes, and one nosecone chute, set in stages to activate the drogues then the other chutes.  Can anyone advise me about how best to deal with this?  

Edited April 24, 2016 by Fearless Son

[Pillow]

You could do a Rescue-Rescue-Mission ans send Jeb to get them. 

[Raideur Ng]

Squad has smartly made it so re-entry is far more vicious than before. You can't just wing it in any vehicle anymore. You will likely end up using pods with the lowest weight possible and lots of chutes. A long object like that will naturally point the heavy end prograde and if its not ready to deal with the heat, you're toast (get it? hur hur). It will also open the chances that even if it tumbles slightly, it exposes large side sections to the airstream, which can wreck them in a hurry if you're already heated up.

Not sure how this changes spaceplanes as I've not progressed that far in career. Using the Hitchhiker container with a command module seems to work better because you can shield it easier.

Long story short, the days of riding any old ship down seem to be over. Dedicated re-entry vehicles are a must now if you want any sort of reliability and margin of error. Maybe John Houbolt was right all along...

[DrMarlboro]

How steep is your descent? A good rule is to only let your periapsis drop to about 30km, which will get you slow enough to not explode before hitting the lower parts of the atmo. 

[Hodari]

I usually have a heat shield on pretty much anything going into orbit at all.  And some sort of reaction wheel as soon as they are available.  Probably not needed for something like this, but better safe than sorry.  And a lot of times, you're better off doing the reentry with just stability assist and not using the retrograde hold option anyway since the latter options uses a lot more electricity. 

With what you have there though, I'd say only use the engines if/when you absolutely HAVE to.  Either when they're getting close to overheating if you don't slow down soon or when you're starting to have serious trouble holding retrograde.  If you can manage to hold at least some of it for when you hit about 20-30km, that's probably the most critical time, but don't be afraid to use it before then if you need to.

And of course, unless you're playing with the option to do so disabled, make sure you quicksave first. 

[Fearless Son]

31 minutes ago, Pillow said:

You could do a Rescue-Rescue-Mission ans send Jeb to get them. 

I might have to, but it would need to be with a different craft, one that has retrograde assistance even without a pilot.  Maybe Jeb can take over for Val and Val can take Jeb's place on the auto-piloted assisted craft.

 

10 minutes ago, Raideur Ng said:

Squad has smartly made it so re-entry is far more vicious than before. You can't just wing it in any vehicle anymore. You will likely end up using pods with the lowest weight possible and lots of chutes. A long object like that will naturally point the heavy end prograde and if its not ready to deal with the heat, you're toast (get it? hur hur). It will also open the chances that even if it tumbles slightly, it exposes large side sections to the airstream, which can wreck them in a hurry if you're already heated up.

Not sure how this changes spaceplanes as I've not progressed that far in career. Using the Hitchhiker container with a command module seems to work better because you can shield it easier.

Long story short, the days of riding any old ship down seem to be over. Dedicated re-entry vehicles are a must now if you want any sort of reliability and margin of error. Maybe John Houbolt was right all along...

Thinking about this design, I may need to start placing fins on the nose of the rocket, so that when it comes in rear-first the extra drag from the fins helps keep it right. That might have a negative impact on ascent, but so long as the stability fins on the bottom of the assent vehicle are bigger and generate more drag than the ones on the nose, it should be okay.  Typically I like to use A.I.R.B.R.A.K.E.S. for this purpose, but I do not have those unlocked yet.

 

5 minutes ago, DrMarlboro said:

How steep is your descent? A good rule is to only let your periapsis drop to about 30km, which will get you slow enough to not explode before hitting the lower parts of the atmo. 

Very shallow.  I lack the fuel for a steep descent.  My last attempt before reverting to quick save actually tried to keep it as shallow as possible, aerobreaking with several passes at 68K altitude until the orbit was terminal.  Same reaction as to the steeper descent: the transition between the upper and lower atmosphere is where I run into trouble.  

 

3 minutes ago, Hodari said:

I usually have a heat shield on pretty much anything going into orbit at all.  And some sort of reaction wheel as soon as they are available.  Probably not needed for something like this, but better safe than sorry.  And a lot of times, you're better off doing the reentry with just stability assist and not using the retrograde hold option anyway since the latter options uses a lot more electricity. 

With what you have there though, I'd say only use the engines if/when you absolutely HAVE to.  Either when they're getting close to overheating if you don't slow down soon or when you're starting to have serious trouble holding retrograde.  If you can manage to hold at least some of it for when you hit about 20-30km, that's probably the most critical time, but don't be afraid to use it before then if you need to.

And of course, unless you're playing with the option to do so disabled, make sure you quicksave first. 

Unfortunately I lack anything but the most basic heat-shield at the moment.  I am not sure exactly what heats up the fastest, but I know that if I turn even just a little bit the heat gauges on the radial elements (chutes and solar panels) fill up quickly, necessitating a quick correction.  If the entire craft flips, the whole thing blows up almost instantly and I can never be sure exactly what went up first.  I am not too worried about stability assist though, between the large battery reserve and the solar panels, and with only a small command pod to generate rotational torque from, I am confident I have sufficient electricity to get down to a safe level to deploy chutes.  

I stress, the really difficult part of this is getting the craft down to a speed safe enough to deploy the parachutes.  If I can do that, everything will be fine, but I seem to have trouble surviving the band of atmosphere in the 40K to 30K range where my speed is too fast and not slowing quickly enough.  

[katateochi]

The problem isn't heat, it's slowing down enough to deploy chutes.
I roughly recreated your craft, used hyper edited to put it into orbit and adjust the fuel levels. Tried a couple things.... and found 1 bug! 
So my idea was to use the command pod as a heat shield; set the craft to re-enter prograde (quite steeply) and move Val (Jeb in my case) into the passenger section and just let the craft free fall. That was going fine, until the command pod exploded and I found myself stuck in mid air, not actually moving at all. ok bug, moving on...

(note the speed on the navball, 0m/s, eh?)

So then I tried a more shallow descent, Pe at 30, re-entry prograde, SAS off and let the craft do it's thing.  Heat isn't the problem. lost all solar panels and the front chute, but by the point I was down to 13km the battery was still there;


And lower down still mostly intact. battery on the command pod (and the command pod) still in place. only the font chute and panels gone.

But problem was it was still moving too fast to deploy the chutes.  First attempt was disaster. Second attempt I managed to deploy the drogues just before reaching the water, the craft spun round and smashed into the ocean, one part survived, the passenger section.  If I'd only been quick enough to move jeb before back the crash it would actually have worked!

So you could either try the stunt option and move Val back at the last minute (I can't remember, but I don't think you can deploy chutes while in passenger section), but you'll have to be really quick.  Or maybe try an even shallower re-entry.  But face first (sorry, prograde) with a shallow reentry and the craft will take the heat.  

side; I've been messing about with spaceplanes today, no heat shielding and doing returns from Mun, just have to do a couple shallow passes and reenter at about a 45 deg pitch, things get hot, but not terminally so (unless the power ran out and I lost control!). 

 

[LameLefty]

You really need a decoupler of some kind on your re-entry vehicles to reduce the mass you're returning. Place one above the fuel tank and drop your tank/engine as soon as you've fired your engine for re-entry. Set your Pe at about 32km and use a heat shield. Yes, they're heavy but they work. With that much mass you'll probably need at least 4 radial chutes plus one on the nose of the capsule. Set them to deploy at 1200m instead of the standard 750m. You'll have more "vertical cushion" as they deploy and you decelerate. 

Edited April 24, 2016 by LameLefty
typos - damn autocorrect

[katateochi]

Just tried it again, still prograde reentry, but with a Pe of 45km (or was it 40km, around there).  Worked fine! Just point it prograde, switch of SAS and let it do it's thing.
The only hair-raising bit is near the ground, you don't have long to deploy the chutes, but it's possible (I also had a hill to make matters worse).
Managed to deploy drogues just about 1.5km up and was able to deploy the main ones just slightly after.

 

[zarakon]

Tried it katateochi's way, and it worked for me too

[bewing]

Come in with the nose pointing 270 on the horizon (basically retrograde), Pe at 50km, SAS stability on. Burn every last drop of fuel when it hits 45km. Then turn SAS off, and encourage the craft to tumble (by using the reaction wheels to turn the craft faster in whatever direction it's already turning). You will then end up with katateochi's reentry, but you will be going a lot slower at the beginning of it.

For bonus points, come in with the nose pointed straight up, until you are down to 55km -- then switch to pointing at the horizon. This will probably knock another 50m/s off your reentry speed.

PS. I usually find it's better to have an automated drone in orbit to make the first close pass to the stranded victim. This allows the victim to EVA before your rescue ship gets there. Then the kerbonaut can do the entire orbital docking maneuver with your rescue ship using their own propellant.

Edited April 25, 2016 by bewing

[Fearless Son]

Thanks, @katateochi, I think your prograde maneuver will work for me.  I might have to sacrifice the nose cone parachute, but I should be able to land it safely with just the drogues and radials.  The maneuver about sacrificing the command pod to use the passenger cabin would not work though as I have all three seats occupied (Val in the command pod and two rescues in the passenger cabin.)  

[katateochi]

8 minutes ago, Fearless Son said:

The maneuver about sacrificing the command pod to use the passenger cabin would not work though as I have all three seats occupied

and also you can't actually control anything from in there (which makes sense). I wasn't sure of that before, but that rules that option out.  But the face first plumet worked and with the remaining 4 chutes I landed without breaking anything else, so you should be fine. Just do a save first!! 

[samstarman5]

At the start when I just have the small Mk1's, I do a shallow re-entry and save a bit of fuel for during. It helps curb the speed enough to get those chutes out.  I've actually found the Rockomax Adapter a godsend for bringing smaller pods down, as it acts as a big airbrake. I definitely suggest getting that unlocked asap.

[ag3nt108]

This craft is very similar to my rescue one craft I use for these missions, mine lacks the drogue chutes and doesnt have any solar panels as I have yet to unlock them.  On reentry I aim for a PE of about 20Km.  I keep SAS on but only at the entry level of SAS and manually nudge the craft now and again to hold retrograde (i.e. i don't have the pilot hold retrograde).  This works just fine until the craft hits around 1200 m/s at which point the craft really wants to flip around and go nose first.  I usually manually hold the craft as horizontal as possible since at around this time ill be at about 12km altitude.  The horizontal resistance of the craft as it hits 10Km and thicker air really starts to slow it down and I can usually just about get away with deploying my chutes at 290 m/s around the 2.5 km Altitude mark.  If it does go nose first due to my pilot error its unrecoverable and won't slow enough to deploy chutes.  Its so cheap and cheerful I also use it for tourist contracts of sub and orbital.  Costs me about 9k a launch,

[RCgothic]

It's not an advantage to keep fuel or engine to burn lower in the atmosphere. You just increase your mass to drag ratio, which means you're going faster when things start getting nasty. Definitely dump that fuel as soon as possible, even if it means burning radial to keep your pe up.

I second a 45-50km pe and broadsided entry, turning prograde only when your reaction wheels can't hold it anymore. Good thing you packed reserve chutes. I do too!

[Fearless Son]

4 hours ago, RCgothic said:

Good thing you packed reserve chutes. I do too!

I like having a wide safety margin (and it lets me recover more pieces of the craft on landing which is important early game when funds are tight.)

[Dispatcher]

On April 25, 2016 at 8:11 AM, Fearless Son said:

I like having a wide safety margin (and it lets me recover more pieces of the craft on landing which is important early game when funds are tight.)

Slightly off topic:  I like your icon (yay Marathon series!).  Back on topic:  I too try to keep my Kerbals (and hardware) relatively safe.  Sometimes the extra mass of a chute or two is well worth the cost.

[Aragosnat]

On ‎4‎/‎24‎/‎2016 at 4:00 PM, katateochi said:

Just tried it again, still prograde reentry, but with a Pe of 45km (or was it 40km, around there).  Worked fine! Just point it prograde, switch of SAS and let it do it's thing.
The only hair-raising bit is near the ground, you don't have long to deploy the chutes, but it's possible (I also had a hill to make matters worse).
Managed to deploy drogues just about 1.5km up and was able to deploy the main ones just slightly after.

 

One thing I'm noticing with these pictures is. You are not comming in remotely level. If you where to do such. The passanger craft and the pod would actually provide some lift upwards. Mainly from the passanger part though.

[katateochi]

5 minutes ago, Aragosnat said:

One thing I'm noticing with these pictures is. You are not comming in remotely level. If you where to do such. The passanger craft and the pod would actually provide some lift upwards. Mainly from the passanger part though.

Part of the problem that OP posed was that the pilot didn't have the training to maintain prograde or retrograde heading, so I was seeing how it would be if things were even worse and it didn't have enough power to maintain SAS. So I just let it free fall and orientate itself how it liked with SAS switched off.  You're right though a bit of upwards pitch might have slowed reentry some and made it easier to deploy chutes, but then I was concerned about keeping the passenger section as protected from heating as possible.  

[sardia]

Some mod options.

Use mechjeb and have that aim prograde or retrograde for you. Alternately, use KIS to remove unneeded parts right before deorbiting.

[Fearless Son]

10 hours ago, Dispatcher said:

Slightly off topic:  I like your icon (yay Marathon series!).

Always makes me happy when someone recognizes that.  One day I will put a very large asteroid into orbit of Dres and turn it into a colony ship to send out of the system.  

8 hours ago, katateochi said:

Part of the problem that OP posed was that the pilot didn't have the training to maintain prograde or retrograde heading, so I was seeing how it would be if things were even worse and it didn't have enough power to maintain SAS. So I just let it free fall and orientate itself how it liked with SAS switched off.  You're right though a bit of upwards pitch might have slowed reentry some and made it easier to deploy chutes, but then I was concerned about keeping the passenger section as protected from heating as possible.  

I tend to use SAS sparingly, turning it off when I can keep it level by myself, then turning it back on when I really need it.  Since I have solar panels on it, as long as I bring it down on the day side I should be able to keep the power balance positive (at least if and until the solar panels burn off.)  

5 hours ago, sardia said:

Some mod options.

Use mechjeb and have that aim prograde or retrograde for you. Alternately, use KIS to remove unneeded parts right before deorbiting.

Eh, I try to avoid mods when I can.  Too temping to fall down that rabit hole.  

Edited April 30, 2016 by Fearless Son

[Dispatcher]

7 hours ago, Fearless Son said:

Always makes me happy when someone recognizes that.  One day I will put a very large asteroid into orbit of Duna and turn it into a colony ship to send out of the system.  

I tend to use SAS sparingly, turning it off when I can keep it level by myself, then turning it back on when I really need it.  Since I have solar panels on it, as long as I bring it down on the day side I should be able to keep the power balance positive (at least if and until the solar panels burn off.)  

Eh, I try to avoid mods when I can.  Too temping to fall down that rabit hole.  

Less on topic:  I would love to see the Marathon in the Kerbol system.    While I've never played Minecraft, these guys used it to eventually "build the Marathon" in Mars' orbit:

https://www.youtube.com/playlist?list=PLIof4Cp3-cakENfeGfWc8qALxAfxQ7K-i

Skip to where they have reached Mars.  They also have co-op play throughs of the Marathon series and a few 3rd party scenarios.

More at topic:  I agree about mods.  I only use what I think should be stock (KER and my own parts).  But KSP is all about finding one's own way into space and back, and that includes mods for some.  Also, I try to have a variety of tools for deorbiting:  spare fuel/ oxidizer, monopropellant thrusters and also reaction wheels to help orient the craft without using up all the propellants.

[Jart]

I posted this in another thread but it is topical here.

 

Pod >service bay (chutes stowed inside)< Crew cabin  Fuel & engine or heat shield

open the pod bay doors late in your descent when things start to wobble a bit for a bit of drag and stability

I am a safety freak for my kerbals so I often have an OKTO in the service bay as well.

 

Happy Landing!

Edited April 30, 2016 by Jart

[Aragosnat]

11 hours ago, Fearless Son said:

Always makes me happy when someone recognizes that.  One day I will put a very large asteroid into orbit of Dres and turn it into a colony ship to send out of the system.  

I tend to use SAS sparingly, turning it off when I can keep it level by myself, then turning it back on when I really need it.  Since I have solar panels on it, as long as I bring it down on the day side I should be able to keep the power balance positive (at least if and until the solar panels burn off.)  

Eh, I try to avoid mods when I can.  Too temping to fall down that rabit hole.  

While I use SAS sparingly as well. That 250 happens to be plenty for re-entry on Kerbin. Most I have used was 100-150 electricity and that is without solar panels and just a probe core with the double seater as that was just from me playing around with the craft a lot. Thing is if you can get the speed down to 1400 m/s or less with the engine taking the brunt. You can then safely turn around and use the craft parts for lift up. Most of the time when SAS in use if you are following the retrograde? marker in. You should be using 0.24 to 0.29 electricity about and if you kept the solar panels on and are in the day light. Then you will never have to worry about energy usage anywas. So go use SAS like no tommorow. =^.^=