Beginner question 1.0.4: Re-entry on kerbal in training section To The Mun: Part 2

[enthusiast]

Hi there,

I'm a complete beginner, but enjoying Kerbal, playing version 1.0.4. Just wondering if anyone of you managed to re-enter Kerbal and land successfully in the training scenario To The Mun: Part 2?

After reading a few of other people's forum quips, I've tried low orbits, shallow angle re-entries, re-orienting the capsule to have the tip pointing away from the heat, however every time the result is the same: The parachute burns up from heat whether I deploy it or not. Also it seems in the earlier versions of the Kerbal, the heat did not really start until 35,000m above ground, whereas in my version the heat already starts at 55,000m above ground. The parachute also seems to deploy automatically sometimes even without me pressing any buttons...

I don't quite understand what I'm doing wrong?

Thanks for any hints!

[Vim Razz]

Having just tried it out to make sure I knew what it asks you to do, the first thing I'd recommend would be to right-click on the parachute and set the altitude it opens at to 1000m or so. The 500m it's set at was fine for the pre-release atmospheric model, but it's a little low for the current game.

After that, are you trying to steer the capsule manually while passing through the atmosphere? It can be a bit twitchy, so I suspect you might be over-steering it and exposing the parachute to re-entry heat as a result, but I have no way to be sure with the information available.

It happens to be designed to fall correctly if it's on it's own and unpowered, so try switching SAS off (by pressing "T" so the light on the navball goes out) and let it orient itself on the way down. Right-clicking on the parachute during decent will also tell you if it's safe to deploy the parachute yet or not.

Edited September 23, 2015 by Vim Razz
grammar is hard, mm'kay....?

[The_Rocketeer]

Firstly, when setting your re-entry, don't set your periapsis any lower than about 30km. If you come down too fast, fire and death will be your reward. You need time to shed that speed before you sink much lower than this into the atmosphere.

Also it seems in the earlier versions of the Kerbal, the heat did not really start until 35,000m above ground, whereas in my version the heat already starts at 55,000m above ground.

Yes, the atmosphere has been overhauled, but most of the effects you see above about 35km are just lights and noise and general excitement, not serious heat generation. The good news is, at this altitude you're shedding velocity without getting too hot. As you get lower things get hotter, and that's where you have issues of fire and death, especially below 20km, and very especially below 10km.

If you follow my advice at the top, you should slow down more gently and avoid overheating.

The parachute also seems to deploy automatically sometimes even without me pressing any buttons...

I don't quite understand what I'm doing wrong?

When you're approaching Kerbin and you separate your fuel tank and engine, is the parachute set to the same stage as the stack separator? If so, when you press space to get rid of the rest, it will also 'arm' the parachute. Then as soon as the air pressure is high enough, the parachute will self-deploy, even if you're still going too fast. To avoid this you can set the parachute to its own stage by clicking the little 'plus' button by the stage indicators on the left and dragging the parachute icon onto the new stage tab. Then drag parachute stage to the top.

If the parachute is already on its own stage, just be careful not to press space again after you've separated the engine.

Of course, it's possible you're not doing anything wrong at all - KSP is still carrying around a fair few bugs.

The parachute burns up from heat whether I deploy it or not.

Is the parachute part exploding, or is the chute envelope being destroyed after deployment? These are different things with different implications:

If the parachute is exploding, that means it's getting too hot, so my advice at the top should solve this.

If it's being destroyed after deployment, that means it's deploying too soon. That's partly covered by my other advice, but it's also important not to deploy the parachute when you're still going too fast. The safe-limit is around 250m/s - if you're going faster than this, that's too fast to use the chute. If your re-entry is shallow enough to not explode but not shallow enough to slow down for chute-deployment, you might need to tweak your re-entry periapsis. Which way (higher/lower) depends a bit on exactly what's happening - if you're slowing down horizontally but then falling too fast vertically, your periapsis is too high, so you need to lower it. On the other hand, if you're still travelling horizontally/diagonally too quickly, your periapsis was too low - you need to raise it up so you slow down a bit more a bit higher. An ideal re-entry will check your horizontal speed at just the right altitude to deploy the parachute before you accelerate into a vertical fall.

Edit: note that any re-entry should start at near-horizontal and end at near-vertical. If you're beginning re-entry on a near-vertical trajectory, you're always going to die.

[Clear Air Turbulence]

N00b here too. But I have found (I think!!) that one way of making sure parachute does not overheat / burn up is to make sure that I am pointing retrograde as I enter the atmosphere. I seem to be able to remain quite stable in the air for the first 40 000 metres of descent or so. My theory is that this protects the parachute, and so far it has worked.

[Highguard]

I can confirm that the parachute in that tutorial has not been corrected for the new aerodynamics and will fail to brake the capsule unless you change its settings as suggested by Vim. This topic has been reported and commented on in a few threads before - you are not alone in being caught out! Rest assured it isn't your faulty flying :-)

[enthusiast]

Thanks for all your helpful replies! I set the parachute to open at 1000 m instead of 500m and prevented myself from clicking deploy until the velocity was below 250 m/s and it worked perfectly!

[Cilyan]

Same with version 1.0.5.0

No heatshield on the capsule, so after having managed a re-entry with no electric power but keeping the tank and using RCS to brake and keep stable, preventing overheating the capsule, I ditched the below stage only when all tanks were empty. Then, I joyfully opened the chute below 250m/s at round 6000m, breathing after that precarious maneuver... Only to see the chute not opening at 1000m and I crashed the poor Jebediah ! 

I guess the scenario needs a little fix.