One way stock 1.0 heat shielding is a bit unfair versus old DRE mod's heat sheilding.

[Leszek]

Which is again strange. As Harv said the drag is modelled the same as the mass (and as posters above mention, this is added to the base part and seems working), the drag should be added to the base part (which is directionless if talking about a single part AFAIK). Unless parts now have a direction of drag/resistance and a direction for low drag. In which case, is the heat shield accidentally "flipping" the games understanding of the direction of drag?

My guess from reading the new aero description is that the part does have drag. It is calculated before hand. The shield is then placed below the capsule which for reentry purposes is putting the drag ahead of the CoM since the capsules drag is occluded but it's mass isn't. This is the same as putting fins on the front part of the rocket.

[FlowerChild]

If you look in Kerbal Space Program\GameData\Squad\Parts\Aero\HeatShield\HeatShield1.cfg you'll see this line:

	PhysicsSignificance = 1

Changing that 1 to a zero should turn physics back on for that part. I'm going to give this a try myself right now, as yeah, heatshields seem quite broken right now making reentry with them next to impossible to survive, which is obviously not what one would expect

As a follow up, having changed the above value I was able to dead-stick reenter no problem with a 1.25m heatshield attached directly to the bottom of a Mk1 command pod, apoapsis around 100Km, periapsis of 30Km, 120% heat setting.

Here is a little sequence to show my pod wont tumble, nor is going to burn up on re-entry. Just one nice smooth ride down using a very shallow angle (mostly due i miscalculated my orbits back to Kerbin after a succesfull Munlanding..

The tumbling appears to be related to the heatshield (which you don't have attached in those screens), not the pod itself.

Edited April 27, 2015 by FlowerChild

[Stormweaver]

As a follow up, having changed the above value I was able to dead-stick reenter no problem with a 1.25m heatshield attached directly to the bottom of a Mk1 command pod.

Yup, just came here to say the same thing.

Also, discovered that the rate of ablation seems to have nothing to do with airspeed ala DRE - my command pod got hot on the way up, heatshield was ablating in orbit (while still behind it's fairing) as heat got transferred to it.

[Arran]

For the MK1 pod and the service module you dont need heatshields.. just dead weight when add then to the craft in this setup.

And for the ablator, the Service Module and the MK1 pod, dont use those (granted thats a tat of a confusing decission of SQUAD).

So sticking a heatshield under the MK1 pod and service module, is creating the issue of instability, while you dont need the heatshield there...

Guess problem solved, dont use it when its not needed..

But i dont mind to redo the same thing with a Heatshield, and post the screenies again, as the result will be the same in the end (since i done it with a heatshield too).

[EladDv]

Yup, just came here to say the same thing.

Also, discovered that the rate of ablation seems to have nothing to do with airspeed ala DRE - my command pod got hot on the way up, heatshield was ablating in orbit (while still behind it's fairing) as heat got transferred to it.

this to be expected as heat is not limited to aerodynamic forces alone but heat in general

[FlowerChild]

Yup, just came here to say the same thing.

BTW: Did you happen to notice a *slight* horizontal offset to your trajectory on the way down? I'm wondering if this actually has to do with the center of lift, rather than it being physicsless, with the COM offset due to turning physics on just overwhelming that and causing you not to veer off so severely.

So sticking a heatshield under the MK1 pod and service module, is creating the issue of instability, while you dont need the heatshield there...

Guess problem solved, dont use it when its not needed..

It's needed on 120% heat settings, which is what I'm playing on. The Mk1 doesn't have an integrated shield in stock.

this to be expected as heat is not limited to aerodynamic forces alone but heat in general

But that's not how ablative shields work in the consensus reality, hence his point.

Edited April 27, 2015 by FlowerChild

[EladDv]

But that's not how ablative shields work in the consensus reality, hence his point.

well ablative shielding will ablate away if it's hot enough-whether it's in atmo or not that's basic physics.

[FlowerChild]

well ablative shielding will ablate away if it's hot enough-whether it's in atmo or not that's basic physics.

NathanKell can probably give a much more detailed answer on this given his experience with DRE, but my understanding is that ablation is not just a matter of heat, but of airflow causing the shield to slowly rip away, which is what dissipates it. I think without that airflow the shield will stay intact, and ablation won't actually occur.

Again...no expert here, and I may be wrong as a result, but that was my understanding of it.

[Stormweaver]

BTW: Did you happen to notice a *slight* horizontal offset to your trajectory on the way down? I'm wondering if this actually has to do with the center of lift, rather than it being physicsless, with the COM offset due to turning physics on just overwhelming that and causing you not to veer off so severely.

A couple of pixels to the left of the middle of the retrograde marker? Yeah. It's like that regardless of rotation, something might be a shade off-center.

[Matt516]

So has the problem been pretty well confirmed to be that the heat shield increases mass and applies drag, but doesn't actually move the CoM? Therefore putting the CoM too far back and causing the capsule to not want to point retrograde? If so, this should be fairly easy for Squad to fix in a hotfix, no?

[smjjames]

I think so....

How rapid a turnaround are they on hotfixes and stuff?

[FlowerChild]

A couple of pixels to the left of the middle of the retrograde marker? Yeah. It's like that regardless of rotation, something might be a shade off-center.

Yup, that's exactly what I saw, and it's consistent with what I saw of the problematic behavior before turning physics on for the part, just less amplified. Like I mentioned above, I think turning on physics may just minimize the problem, but not actually be correcting it.

Will try playing around with some of the other values, this in particular looks suspicious to me:

		jettisonDirection = 0 0 1

Which seems to imply that "down" on the model is along the z axis, as opposed to this:

	CoLOffset = 0.0, -0.15, 0.0

Which seems to imply it's along the y axis.

Not entirely certain, but the above looks fishy to me.

[lajoswinkler]

Bug, folks.

http://forum.kerbalspaceprogram.com/threads/116839-Heat-shield-seems-to-be-treated-as-having-0-mass

[dryer_lint]

Tried a simple parachute to keep it stable? I noticed that chutes are a lot less likely to rip your ship into a thousand pieces. And just deployed a single chute for the above reason while I was still going at 1000m/s at 10km.

This, chutes seem a LOT more stable now. They're even a little overpowered, you can open them during the flames of re-entry

[FlowerChild]

Bug, folks.

http://forum.kerbalspaceprogram.com/threads/116839-Heat-shield-seems-to-be-treated-as-having-0-mass

Except it's been labeled as "not a bug"

[smjjames]

Except it's been labeled as "not a bug"

I mentioned that earlier, I don't know if a mod did that out of a misunderstanding or if a dev did it.

[lajoswinkler]

Misunderstanding. This is a bug. Shields should not behave like this and capsules must have low CoM. Developers aren't stupid, they know very well what are blunt reentry bodies.

[Greg310]

Ok this is really dumb. You don't even need a heat shield, you just have to open your parachute at 25,000 meters and all is well. The drag slows you down to a couple hundred meters per second before it even opens. If you try to do it the right way and use the heatshield your spacecraft turns upside down.

Plus if temperature is an issue now, why can't I see what temperature my stuff is? I should be able to right click on a part and see it's temperature right? And if I open the Flight Events log screen with F3, you'd think one of the stats listed on the right would be 'Highest Temperature'. Right??

[FlowerChild]

Plus if temperature is an issue now, why can't I see what temperature my stuff is? I should be able to right click on a part and see it's temperature right? And if I open the Flight Events log screen with F3, you'd think one of the stats listed on the right would be 'Highest Temperature'. Right??

If you open the debug menu with alt-f12, look at the physics tab, and select reentry heating, there's a couple of options for displaying it, either as text in the right click part menu, or graphically (although I find the graphic display is too ambiguous to really be useful).

And yes, not having it display in some way by default is a pretty huge oversight, and I'm not saying otherwise. The above is at least a workaround until it's corrected though.

[MrCynical]

So IT is doable, its just different as before.. Crazy tall small pods just dont work well. Normal sized loads no problems.

What have you got in those utility bays? Something heavy I'm guessing. A simple materials bay or similar in that position and it doesn't matter how shallow you enter the atmosphere, it will flip.

[Columbia]

I haven't tried out 1.0 yet myself.. this sounds a bit of a letdown.

Welp, time to start clipping RTGs and Reaction wheels in the capsule!

[smjjames]

If you open the debug menu with alt-f12, look at the physics tab, and select reentry heating, there's a couple of options for displaying it, either as text in the right click part menu, or graphically (although I find the graphic display is too ambiguous to really be useful).

And yes, not having it display in some way by default is a pretty huge oversight, and I'm not saying otherwise. The above is at least a workaround until it's corrected though.

Yeah, I don't even know what measurement scale they are using.

[EladDv]

kelvin it's in the change log

[Xyrus]

I keep saying to myself that I'm doing this wrong, that there's no way that stuff like this has made it past QA. But I dunno. I might still be trying to do stuff the old-fashioned DRE + FAR way.

<comment deleted>

Nevermind. Bug with heat shield mass.

Edited April 27, 2015 by Xyrus

[Stormweaver]

Right, did a bit of testing with the physics turned on, see about adressing the mat bay/utility bay re-entry.

With just a Utility bay, you can re-enter just fine - you'll be offset a few degrees, but the heatshield takes the vast majority of the punishment. With just a Matirials bay, if you manage to avoid overheating the bloody thing (which can be hard enough to do on the way up, let alone on the way down) you'll need to kick SAS on once heat starts building up, but the reaction wheel is strong enough to handle it. With both...you'll be balancing it by hand, probably with spin stabilisation, and probably want spare batteries.

All in all, it sounds about right.

Quick edit: Had the aero debug arrows on the whole time - Saw nothing but the red 'drag' ones pointing retrograde. Not sure if there should be other ones visable.