Is the lander can good?

[Prat4545]

Hello everyone! i'm a noob

 

Ok so i'm trying to re enter on kerbal after a long exausting mission to eve! (i didnt notice that i need to wait for another travel window)

But i always explode

I got a heat shield and up that a lander can and the beginning explosion is mostly from my lander can!

Also i got a lot of my science stuff attached on the command module above.

I hope you have any suggestions! and dont forget i'm a noob / beginner soo..

Sincerly Prat

[Prat4545]

I forgot to say i'm going around 3000 m/s

 

[Vanamonde]

Howdy and welcome to the forum.

I have moved your thread to the Gameplay questions subforum, where we will attempt answer it. It would help if we could see the craft, though. Got any pics? 

[Spricigo]

Oh well, coming from an interplanetary trajectory you will be much faster than the typical return from Mun/Minmus. As result the aerobraking will generate much, much more heat. 

If a propulsive capture or aero capture  higher is not possible you will need a rescue mission. 

 

[Draalo]

Try a high Kerbin Pe like 45km. First entry shall just slow you down enough to be captured by Kerbin in a high eliptical orbit.

Final Descend will happen on 2nd entry.

[Regor]

The lander can for re-entry is just not good. Sorry, but it's hot tolerance is lower and its shape is terrible for aerodynamics and heat shielding. Use a command pod instead.

[Chequers]

Agreed with mabdi36, when comparing pods, one isn't better than the other: they're designed for two different purposes.

Your lander can is designed for... well... landing. Its shape and dimensions allow for a low centre of mass, and vertical surface for attaching radial tanks and landing legs for plonking down on bodies without atmosphere, such as the Mun.

The trade-off for this low weight and boxy dimension is fragility and a shape not suited for orienting stably through the atmosphere. It isn't designed for re-entry; and while a heat-shield will go some way to helping, if you're screaming in from a transfer from Eve, you're going to run into problems. It sounds like you've brute-forced a transfer, which usually means you're going to be coming in fast.

If you can provide more details about the ship and your transfer, we might be able to help you bring it  back in one piece. I'd suggest trying to bleed off some of that velocity with an aerobraking maneuver.

Edited June 11, 2020 by Chequers

[OHara]

It is awkward for everyone new to the forum to figure out how to put pictures somewhere like imgur and then past the link https://i.imgur.com/tDfB5nd.jpg (in the form with the .jpg ending) here. I'll post an example.

That lander can extends beyond the heat shield that I guess you would have used, so the lander can gets some of the compression heating. KSP roughly realistically simulates which parts feel the shock heating, and how much.

If you made a nice transfer from Eve, you would hit the atmosphere at 3600m/s, so if you can maneuver so your Pe is about 45km, and have no more mass than the can and heatshield, you can aero-capture on the first pass, then after one elliptical orbit you can aero-brake to land on the next pass.

As everyone else said, just skimming the atmosphere at 55km to aero-capturing to orbit and then doing a rescue might be less frustrating and more fun.  Squad made Kerbals immortal beings who need no food and sit happily in space for long periods of time, so we have the flexibility to rescue them later.

[Prat4545]

thx everyone! I was doing it the other day and i did it because i was wiggeling! But thx for the tips now i know that the lander can is not so good for interplanetery approach! Also thx for the guide how to post pictures

[magnemoe]

12 hours ago, mabdi36 said:

The lander can for re-entry is just not good. Sorry, but it's hot tolerance is lower and its shape is terrible for aerodynamics and heat shielding. Use a command pod instead.

Its also can not handle hard landings as well as the capsules or plane cockpits. 
its workable as an lander in vacuum its a bit heavy.
its very nice as an bridge on an station, or large ship as it can be stacked with other 2.5 meter parts 

[Fraktal]

8 hours ago, OHara said:

That lander can extends beyond the heat shield that I guess you would have used, so the lander can gets some of the compression heating.

Actually, in the configuration on your pic, only a minority of the heat taken by the landing can will be from the landing can's own compression heating; most of it will be from part-to-part heat transfer from the heat shield, since the ablator can only dissipate heat so quickly. You can observe this in action by strapping a heat shield to the bottom of a materials bay, setting SAS to retrograde hold and dropping that into reentry from an elliptical trajectory: even though the heat shield fully shields the bay from compression heating, the bay will heat up to a dangerous level anyway because it's touching the yellow-hot heat shield.

If, however, you put something in the way like a service bay, that'll soak up the worst of the heat transfer so that the landing can will survive. Not only that, but the landing can's shape and thus drag means putting the landing can on the top rather than the bottom results in the craft self-stabilizing during reentry, pointing the heat shield prograde without SAS having to hold it there. It'll look stupid, but it'll work.

[OHara]

Yeah, that 'materials bay' that some contracts require frustrates every new player.  Those contracts are really asking for the SC9001 Science Junior.  The Science Junior just barely fits behind the heat shield, so that if you point exactly retrograde, in the 'Surface' frame of reference, the Science Jr. is protected.  The Hitchhiker Storage Container is similarly difficult to re-enter.

A related thing that was not obvious to me when I was a noob, was that any Kerbal can 'Collect Data' from the Science Jr., and take the data into the capsule, so we do not need to bring back the Science Jr. itself.

Yet another thing that was not obvious to me, is that ablator does very little good.  When we run out of ablator, the heat shield gets a little hotter, but it just radiates heat faster and comes to a steady state at a higher temperature.  The heat shields must have some incredible insulation because their internals stay cool and sometimes conduct heat away from the rest of the craft.

If you get curious, you can use the debug menu (alt-F12 on PC) under Physics::Thermal::Display_in_action_menus and see what KSP is thinking about heat.  The signs of heat flux are + for flows that make the part hotter, − for flows that are removing heat.

[Fraktal]

Ouch, that landing can there is running very hot, mate! Less than 80 degrees away from exploding!

[Prat4545]

Haha! Thanks for the help!