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

[ola]

Okay. I just imagined that they were thick and heavy or something. A ton would probably have been a massive exaggeration anyway.

You should really look at how SpaceX manufactures the heat shield for the Dragon capsule, it is quite cool.

But I digress. I'll watch the SpaceX launch and go to sleep and hope that the modders have caught up in the CEST morning, so I can continue to avoid anything stock.

- - - Updated - - -

Okay. I just imagined that they were thick and heavy or something. A ton would probably have been a massive exaggeration anyway.

- - - Updated - - -

As for the chutes not ripping apart, they did that in 0.90, they won't rip apart even if you reenter at 14k m/s.

Unless you use mods made by someone close to frighteningly gifted. Yes, NathanKell, I'm looking at you.

[Dunbaratu]

I'm about to head out for the evening, but here's some pictorial proof of what's screwed up:

Here's a Mk1 command module in the VAB. Notice it has a mass of 0.84 and notice I have the center of mass yellow ball turned on.

Now, here's a stack of 80 heat shields attached just under it. Each heat shield allegedly is supposed to have 0.3 mass according to the info panel in the VAB:

So why hasn't the center of mass indicator moved at all? The combined mass of 80 of those heat sheilds should be waaay more than the capsule. And yet the yellow ball hasn't budged.

But the engineer readout IS aware that they did add to the total mass of the vessel, which is now much more than the mass of one mk1 capsule:

So, adding a heat shield DOES add to total mass of the craft, but without moving the center of mass indicator at all. That can't be right.

[Hcube]

So we know that something is haywire with the new heat shields, understood.

But these crazy parachutes... Can this can be confirmed to be working as intended or not? Surviving a 3000m/s re-entry when deployed/armed in atmosphere, without burning up, ripping off, or flattening Kerbols? What new magic material did they discover on Kerbin??!?

Those are just crazy OP. The fact that opening those at 2500m/s can solve the reentey bug annoys me even more than the reentry bug itself. It is 100% counter intuitive. A new player (or even an experienced player btw!!!!) will never be thinking "oh, my capsule is all burning and covered in plasma, time to open the chutes"

HOW dis this pass through experimentals ? It literally is the first thing you do when you start a career game !

EDIT : Yes, chutes also never ripped off in 0.90.0 , but they didnt stop you from 2500m/s to 300m/s in 2 seconds, leaving you at a dead stop at 18000km either.

Edited April 27, 2015 by Hcube

[r4pt0r]

~snip~Bunch of pics and stuff

....Oh. That's interesting.

[Robotengineer]

--snip--

How did this get through QA and Experimentals?

[Johnny Wishbone]

How did this get through QA and Experimentals?

Yeah, I gotta agree with that. If this is legit, and I'm not saying it isn't, that's a pretty big swing and miss.

I know it's not popular to bag on Squad or whatever, but stuff like this is EXACTLY why people are saying this was rushed and shouldn't be called 1.0. Yeah, bugs happen. Yeah, testers don't catch everything. But how do you make a part that has mass, but doesn't change the CoM of a craft? Its not like those 2 concepts aren't intrinsically linked or anything...

[cicatrix]

Speaking of heating - can I stack the heat shields like on the pic above?

[WOODY01]

Also, I don't know if a mod did it or a dev did it, but someone made that massless heat shield bug report thread as [not a bug/intended], so, I dunno, misunderstanding somewhere?

I am going to post my own on the support forum. The thread was about them seeming to be massless since the COG was not changing when adding them. So maybe it is not a bug and working as intended just not sure they tested it on the MKI pod with anything like a service bay or science jr attached protected by a heat shield. Not a huge deal but would be nice to bring those items back with me since it would make logical that since they outweigh the pod the pod should not want to reenter nose first.

[frobnik]

You know, I thought I'd do some testing before posting, but I don't know if the results make sense.

Like others, I noticed I had to manually keep the pod pointed retrograde during reentry, which is not what I expected having played with DRE, so to sandbox I went to test. I launched into a 100 km orbit and reentered to a about 12km periapsis, I pointed the reentry vehicle retrograde at 70 km and the turned SAS off.

With pod, parachute and stock heatshield, the craft soon turned to about 40 degrees off the retrograde, and exploded at 15 km.

With pod, parachute and a heatshield with physics turned on, it stayed on the retrograde, used up less than half of the shield and while coming in quite fast over some mountains, performed pretty much as expected.

Then, pod, parachute and no heatshield at all, fully expecting this to blow up high in the atmosphere, but no, it survived all way down. What the...

[Dunbaratu]

Speaking of heating - can I stack the heat shields?

I only did it to prove the bug, as one shield wouldn't move the center of mass very far, but 80 would make it visually obvious whether it was working or not.

[gompasta]

Yeah, I gotta agree with that. If this is legit, and I'm not saying it isn't, that's a pretty big swing and miss.

I know it's not popular to bag on Squad or whatever, but stuff like this is EXACTLY why people are saying this was rushed and shouldn't be called 1.0. Yeah, bugs happen. Yeah, testers don't catch everything. But how do you make a part that has mass, but doesn't change the CoM of a craft? Its not like those 2 concepts aren't intrinsically linked or anything...

Due to game mechanics, the part is weightless, and the value shown is actually false. This is because small parts are prone to physics glitches when proper collision and weight is applied.

[Johnny Wishbone]

Due to game mechanics, the part is weightless, and the value shown is actually false. This is because small parts are prone to physics glitches when proper collision and weight is applied.

Ok, fair enough. But why list a value at all for it then? Especially something as specific as 0.3? Why not 0.0000001 or something else miniscule?

[Dunbaratu]

Due to game mechanics, the part is weightless, and the value shown is actually false. This is because small parts are prone to physics glitches when proper collision and weight is applied.

The part is emphatically NOT weightless. Read the engineer panel in my third screenshot. If the 80 shields had no mass, the readout would say the vessel weighs just 0.84 - for the mk1 capsule. It's more than 20. It IS adding the mass to the vessel as a whole, but then not letting that mass affect the center of mass balance, which we think is causing the weird behavior. The part still has mass at least for the calculation of total mass of the vessel.

When you extend the length of the capsule without properly calculating in how that moves the center of mass, it causes the center of mass to no longer be below the center of drag, which is the effect that normally makes the capsule go rear-first.

Edited April 27, 2015 by Steven Mading

[Jovus]

Confirmed that the problem is very likely due to the heat shield. I flew very nearly the same profile as before - Mk 1-2 capsule, reentry from 90km, pe set at 8km - but without the heatshield. The pod alone flies straight and true just like you'd expect.

[EladDv]

test it outside the VAB- map view has the most accurate reading

[FlowerChild]

The part is emphatically NOT weightless. Read the engineer panel in my third screenshot. If the 80 shields had no mass, the readout would say the vessel weighs just 0.84 - for the mk1 capsule. It's more than 20. It IS adding the mass to the vessel as a whole, but then not letting that mass affect the center of mass balance, which we think is causing the weird behavior. The part still has mass at least for the calculation of total mass of the vessel.

If I remember correctly, that's just due to the way the VAB mass display works. Parts that have physics turned off still add their mass to that display, but don't actually add mass to a vehicle, thus why the COM isn't changing.

I know this because I implemented a mass display for my mod which DOESN'T include physicsless parts, and it's always very different values displayed than the stock one.

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

[Technical Ben]

Ah. Is this a heating bug? Sounds it's not a COG bug only, but a flip + heating bug? As pod on it's own does not explode? So why would it explode with the heatshield, if not?

I've survived re-entry, but using airbreaks or drogue chutes. Which is less than idea for career.

[Dunbaratu]

Ah. Is this a heating bug? Sounds it's not a COG bug only, but a flip + heating bug? As pod on it's own does not explode? So why would it explode with the heatshield, if not?

The problem isn't heat being broken, it's that the orientation of the vessel flips. The heatshield alters the balance of mass to volume, so the capsule won't go butt-first anymore.

[NathanKell]

And yet IIRC the changelog mentions that finally physicsless parts _do_ add their mass to their parents in flight, they're not massless in flight. If the map view says otherwise, it's wrong. You can experimentally measure this by adding a physicsless part to a sounding rocket and seeing if your apoapsis changes.

[FlowerChild]

Ah. Is this a heating bug? Sounds it's not a COG bug only, but a flip + heating bug? As pod on it's own does not explode? So why would it explode with the heatshield, if not?

The heatshield (at least the 1.25m one attached to a Mk1 command pod) causes some weird kinda drag where your capsule turns partially into the airflow accumulating heat real real fast. I'm playing on 120% heat settings and it's essentially making dead stick reentry impossible with a shield attached.

And yet IIRC the changelog mentions that finally physicsless parts _do_ add their mass to their parents in flight, they're not massless in flight. If the map view says otherwise, it's wrong. You can experimentally measure this by adding a physicsless part to a sounding rocket and seeing if your apoapsis changes.

Interesting Nathan, thanks for the info. Guess they just don't affect COM.

[Jouni]

If I remember correctly, that's just due to the way the VAB mass display works. Parts that have physics turned off still add their mass to that display, but don't actually add mass to a vehicle, thus why the COM isn't changing.

This is something that changed in 1.0. It used to be that physicsless parts were truly massless, but the VAB mass display got it wrong. Now the physicsless parts add their mass to the parent part, but the ship info display in the map view gets it wrong.

[Dunbaratu]

And yet IIRC the changelog mentions that finally physicsless parts _do_ add their mass to their parents in flight, they're not massless in flight. If the map view says otherwise, it's wrong. You can experimentally measure this by adding a physicsless part to a sounding rocket and seeing if your apoapsis changes.

Also, if the VAB says your vessel has mass 30.1, it won't let you launch to the tier 1 launchpad. So it's still counting that mass against you for that rule too.

Is this getting reported as a bug in squad's tracker? Because I think the case "add 1 heat shield and nothing else to a mk1 capsule and it cannot safely re-enter" is pretty clearly wrong, and defeats the point of the heat shield.

[tater]

I checked, and unlike DRE, the mk1 has no ablation value without a shield. It does reenter properly (attitude wise) with no shield. The shield part is screwy.

[Technical Ben]

The heatshield (at least the 1.25m one attached to a Mk1 command pod) causes some weird kinda drag where your capsule turns partially into the airflow accumulating heat real real fast. I'm playing on 120% heat settings and it's essentially making dead stick reentry impossible with a shield attached.

Interesting Nathan, thanks for the info. Guess they just don't affect COM.

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?

[Arran]

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..

Still on the mun..

Breaking at 30km, all temps within its limits, pod stable facing the right way..

Becoming a fiery ball of fire, chute still not deployed, holding SAS for stability...

Coming out of the fire ball, the HeatWarning Thermometers showing i was getting very hot, but just below breaking point.

Succes, allready cooling down now..

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