Does the 1.25 heatshield matter anymore?

[Firemetal]

Before 1.1, you were able to dive into the atmosphere at 4000 m/s from interplanetary space and come out without a scratch. Now, I can't even come back from the mun without burning up and exploding. Its as if I don't have the heat shield on!

Is this supposed to happen?

[Snark]

Can you provide a bit more detail?

• What's your ship mass?
• What's your Pe before hitting atmosphere?
• What's your speed when you hit atmosphere?

I use the 1.25m shield all the time, and it works great.  No problems with it.  I usually take off most of its ablator, because I rarely need more than about 25% and would rather save the mass.  But whether it "works" or not completely depends on how you use it-- like pretty much everything else in KSP, if you're "Doing It Wrong" it'll bite you. 

Moving to Gameplay Questions.

[Spaceception]

Try turning down the reentry effects, I haven't had those problems with capsules yet, but spaceplane tests end up in a fiery explosion.

[Mjarf]

The aerodynamics are more realistic now, so you have to slow down before re-entry. I always enter a 100-200km orbit before doing the re-entry, this way I don't really need heatshields.

[cubinator]

How low is your periapsis? I usually have mine pretty high for a Mun-intercept, around 40 km, and I always use any fuel left in the ship to slow down before hitting the atmosphere, keeping my periapsis up.

[VaPaL]

Well, I discovered that it's possible to set my Pe at 25km direct when returning from Minmus and reentry with no problems. With 2,5m capsule and heatshield. Only uses 50-60%¨of the ablator avaible. My ship it's just these, a parachute, and for SSDs from a mod with the science I gathered.

Try differents Pe, no to shallow nor to steep.

Edited June 10, 2016 by VaPaL

[Firemetal]

Uh... I just use either the mk1 cockpit or mk1 lander can with a parachute or two and a heat shield. I used that all the time in 1,0,5 and I was fine but now... I can't enter the atmosphere without exploding due to re-entry heating. I came from Moho about a week ago and slowed down to about 2700 m/s but I still burned up 15 seconds into re-entry. I went to Eeloo and made sure I used the 3 kerbal cockpit AND circularized around Kerbin before re-entry and I was fine but that wouldn't of happened with the 1.25m cockpit. ???

[Snark]

3 minutes ago, Mjarf said:

The aerodynamics are more realistic now, so you have to slow down before re-entry. I always enter a 100-200km orbit before doing the re-entry, this way I don't really need heatshields.

...Maybe won't need heatshields, but will need plenty of fuel to slow down.  Fuel that masses a whole lot more than the heatshields would.

If you're coming in at some insane speed like 10 km/s or something, then yeah, you're going to need to slow down some before hitting atmosphere.  But a properly designed craft with an appropriate heat shield on it can hit atmosphere at well above 3000 m/s and will survive just fine.

Pretty much any interplanetary Hohmann-transfer orbit ought to have no problem with a heat-shield reentry; it's only when you're going on significantly suboptimal transfers that the velocity gets so high that they need a little extra help.

[Firemetal]

I try 30k usually. But I always burn up. I came from Dres in 1.0.5 and I was on a collision course with the planet but the heatshield did it's job and I came out fine. Now I was playing career yesterday and all my science equipment went first, then my command cockpit. It's as if the heatshield doesn't exist!

[Mjarf]

Yeah I know, but I'm paranoid about having enough delta-v so I usually have plenty fuel left before re-entry anyway. If I played career I'd probably use heatshields to build more efficient crafts. I also really really don't wanna hurt my little green dudes, so I usually land very carefully.

[Firemetal]

9 minutes ago, Mjarf said:

The aerodynamics are more realistic now, so you have to slow down before re-entry. I always enter a 100-200km orbit before doing the re-entry, this way I don't really need heatshields.

Wait 1.1 changed the aerodynamics again?

[N_Molson]

It definitively sounds like your entry angle is much too steep. For a munar reentry, I typically tune my Kerbin periapsis to 20,000 meters, for a velocity of 3,200 m/s at entry interface.

Also, make sure you are reentering "Eastwards", just like the same way you launch. Else you'll have Kerbin's rotation against you, and it will add to your velocity.

[Firemetal]

4 minutes ago, Snark said:

...Maybe won't need heatshields, but will need plenty of fuel to slow down.  Fuel that masses a whole lot more than the heatshields would.

If you're coming in at some insane speed like 10 km/s or something, then yeah, you're going to need to slow down some before hitting atmosphere.  But a properly designed craft with an appropriate heat shield on it can hit atmosphere at well above 3000 m/s and will survive just fine.

Pretty much any interplanetary Hohmann-transfer orbit ought to have no problem with a heat-shield reentry; it's only when you're going on significantly suboptimal transfers that the velocity gets so high that they need a little extra help.

Well I did slow down and I still burned up so I have no idea what is going on.
Even with the heatshield!

2 minutes ago, N_Molson said:

It definitively sounds like your entry angle is much too steep. For a munar reentry, I typically tune my Kerbin periapsis to 20,000 meters, for a velocity of 3,200 m/s at entry interface.

Also, make sure you are reentering "Eastwards", just like the same way you launch. Else you'll have Kerbin's rotation against you, and it will add to your velocity.

Dude thanks but as I said I ren-entered at 3000 m/s with a collision course with the planet AND the mk1 lander can and survived it without a scratch so it doesn't make any sense to be the steepness but the rotation might be a problem? Nah I used to be able to say "I'm going so fast but I don't need to worry because I got my heatshield" but now I can't even re-enter from the Mun. Maybe its cause I used to play on easy mode and now I'm playing normal. Idk but to prove it, I'll go into a 1.0.2 game and re-enter from the mun steep as heck.

[FullMetalMachinist]

24 minutes ago, Firemetal said:

Maybe its cause I used to play on easy mode and now I'm playing normal.

I think that's (at least partly) the cause of your problems. Easy difficulty has the reentry heat that is generated turned down. 

[Firemetal]

probably but I'm testing it right now with an earlier version.

\

[Firemetal]

Guys. I'm not sure if the aerodynamics changed between 1.0.2 and 1.1 but I came back to kerbin from the Mun on a collision course with the planet at 3200 m/s and I didn't even see the heat meter. ?!

[bewing]

The aerodynamics are the same, but all the MK1 parts had their drags reduced by 25% in the new version. So you don't slow down. So you go kaboom. If something worked before in 1.0.5, that is no guarantee that it should work now.

Are you closing the doors on your ScienceJrs? Have you tried a 45km Pe?

[Firemetal]

38 minutes ago, bewing said:

The aerodynamics are the same, but all the MK1 parts had their drags reduced by 25% in the new version. So you don't slow down. So you go kaboom. If something worked before in 1.0.5, that is no guarantee that it should work now.

Are you closing the doors on your ScienceJrs? Have you tried a 45km Pe?

Uh does the drag mean a heat shield not doing it's job?

[bewing]

No, but it means the heat shield has a lot more work to do than before.

[X-SR71]

This might be a stupid hint but, are you sure your heatshield is facing the retrograde vector all the time during reentry? I find that even the slightest angle will cause the capsule to get heated much quicker. Be sure to hide all your craft behind the shield. 

Edited June 10, 2016 by X-SR71

[Firemetal]

It is roughly on the retrograde. I have trouble getting it centered completely and the mk1 lander kinda sticks out from behind the heat shield. C'mon atmosphere, how the hell do you expect me to get to a 2.5m cockpit if you keep blowing up my science? Plus I could make a rocket with a lot of DV but only if I can minimize the mass of the command pod!

 

squad could you please make it so the heat shield actually shields the spacecraft from heat pls?

Edited June 14, 2016 by sumghai
Reduced text size to a more sensible value

[FullMetalMachinist]

@Firemetal I understand that this is frustrating. What you're describing doesn't sound like it's past the capabilities of the heat shield, and others have said that pretty much the same thing you're doing works for them. 

So that leaves two possibilities, either you're being more aggressive with reentry than we think, or your 1.1.2 game is bugged. 

For the first issue, a couple of screenshots will help loads. If you could post one in map view that shows your orbit right when you start reentry, with the AP and PE markers showing the numbers. And one showing the part of your craft that is reentering, maybe one in the VAB and one during reentry, right before everything goes kablooie. 

As for the other possible problem, when you started playing with 1.1, did you update an existing copy of the game, or did you download a fresh install? If you updated (especially with the patcher) it's possible that something went wrong and messed up your install of 1.1. I would suggest first trying to delete your physics.cfg from the main KSP folder. This will force the game to make a new one with the default values when you restart the game. If that doesn't work you can try downloading a fresh copy. If you're using Steam try verifying the integrity of the game cache. 

[Firemetal]

I will do that a little later thanks.

[Snark]

Hi Firemetal,

So, some specifics:

• If your craft is lightweight (only a ton or two), and
• your craft design has its CoM close to the heatshield (i.e. the craft doesn't want to flip), and
• you have a reasonable Pe on Kerbin approach (e.g. 30 km works well), and
• you're not going too fast (e.g. not a whole lot faster than 3000 m/s when you hit atmosphere)

...then it should enter really trivially easily with no problem, unless something weird is going on.  Even with a lander can.

Since you're having problems, it seems likely that you may be having an issue that we aren't spotting because we don't have the information.  So, there are a few things you can do to help us help you. 

• Give us a screenshot of your reentering vehicle, and let us know what its mass is.
• Also include your velocity when you hit atmosphere, and your Pe.
• Keep it simple, don't need to hear about 1.0.2 or whatever, just tell us what you're trying in 1.1.2 that's not working.

I use the heat shield on lander-can reentry vehicles coming back from the Mun or Minmus all the time, and it works just fine.  However, it is important to keep pointed well retrograde so that the can isn't peeking out from the heat shield more than it has to.  That's easiest to do if you have at least level-1 SAS aboard (i.e. a level-1-or-better pilot, or a HECS-or-better probe core), so you can just click the "hold retrograde" button and be done with it.

If you don't have that available yet, and are having trouble holding close to perfectly retrograde, then you may want to try using a Mk1 command pod instead of the lander can.  Yes, it's a couple of hundred kilograms heavier... but on the other hand, its conical shape makes it much easier to hide behind the heat shield, and it's tougher in general.

Also, you mentioned "blowing up science":  Do you mean that you have all your science in the lander can with your kerbonaut, and that's blowing up?  Or do you mean that your science is still sitting inside your science instruments, and they're blowing up?  If so, there are things you can do to protect the science:  e.g. putting the instruments inside a service bay to protect them, or (even better) collect the science out of them before you hit atmosphere, and stash it in the command pod with your kerbonaut.  That way, as long as the command pod survives, it doesn't matter what happens to the (fragile, easily burnable) science instruments; your science is safe.

[Firemetal]

Yes I have updated the game. I deleted physics and did a Mun flyby. Set periapsis at 15km and hit atmosphere at 3200km. I had a Mk16 parachute on a mk1 lander can and a 1.25m heat shield. At hitting the atmosphere, I was already at 50% critical thermal percentage. This really isn't fair. It's as if I don't have a heat shield.

Soon I'm switching back to 1.0.5.

Edited June 10, 2016 by Firemetal