[0.20] Deadly Reentry 2.3 - reentry heat, plus thermal and g-force damage to parts

[ZobrAA]

One more bug found. New sound didn't actually sounds properly... The volume of fire_damage and aspeshialy gforce_damage are too loud, they just didn't used the game volume levels and always play at max levels. It was very bogus and even creepy when I heard it first time.

[Frederf]

I would support this. I use RemoteTech and like to drop small probes without an interplanetary dish on them. Keeping an orbiter in range until landing is sometimes quite hard and I've lost a lander probe because I lost contact before I opened the chutes.

Also, I just want to say how thrilled I am by the new features in this mod. Great work!

I just tried DR2.2f and while that's what I wanted to do it turns out that (perhaps with FAR?) waiting for Mach 1.0 basically means waiting until after impact which is a little late for parachutes. I used to get down to 200 m/s at 5,000m or more which was a good time to pop chute. Now I'm practically impacting at 400. I need to rework my post reentry recovery procedure.

[CaptainArbitrary]

I've got a bit of a bug to report. I was coming in for reentry about Jool, coming in at about 9km/s with periapsis at 120k. My 6.25 inflated heatshield blazed white hot, but the temperature barely made it to -30.

I might be able to corroborate this. I've seen similar things a couple times on 2.2f  things not burning up when I expected them to  but I haven't investigated it until now. I was just deorbiting the upper stage of a GTO mission that failed to make its trajectory. It was a 1.25-meter upper stage with a KW fairing decoupler on it, and above that a satellite with no temperature tolerance to speak of. (I set my "fragile" parts to have maxTemps of 600°C, which is about where aluminum starts getting weak on you.)

This time, during atmosphere interface, I turned on DR debugging and took screenshots.

Note that the vessel was coming in retrograde, engine first. Here's what I saw:

Note that DR thinks the engine is shielded from the shockwave. It's not, obviously. Also:

This extending antenna (from the AIES part pack) is also showing as shielded from the shockwave. That might be behaving-as-expected, because I think the collider on the part is way smaller than the part looks in its extended state. But it's still counterintuitive.

Under 10,000 meters, aerodynamic effects (note that I'm running FAR) flipped my vehicle over so it was falling right-side-up.

As you can see, DR does not think the dish is shielded. It does still think the engine is, though, which is reasonable considering the vessel's attitude.

Short version? However DR figures out that a part is shielded from the shockwave isn't working 100% reliably, is my guess. So sometimes reentry heating doesn't happen when it really should.

[Killerblonde]

One more bug found. New sound didn't actually sounds properly... The volume of fire_damage and aspeshialy gforce_damage are too loud, they just didn't used the game volume levels and always play at max levels. It was very bogus and even creepy when I heard it first time.

Oh yes. The fire sound also sounds more like rubble falling than fire. I literally thought my computer had a virus, and it gave me quite the scare for awhile when I had no idea what it was or where it was coming from....

[ialdabaoth]

Oh yes. The fire sound also sounds more like rubble falling than fire. I literally thought my computer had a virus, and it gave me quite the scare for awhile when I had no idea what it was or where it was coming from....

Sound effects will be MUCH better in the next version, don't worry. The newer version adjusts volume and pitch based on how much damage has occurred, and how quickly it's occurring.

[bulletrhli]

I did not know you had a debugger. Interesting.

[SchroedingersHat]

I just tried DR2.2f and while that's what I wanted to do it turns out that (perhaps with FAR?) waiting for Mach 1.0 basically means waiting until after impact which is a little late for parachutes. I used to get down to 200 m/s at 5,000m or more which was a good time to pop chute. Now I'm practically impacting at 400. I need to rework my post reentry recovery procedure.

I've been having trouble with that regard, too. I think the problem may be the density of the command pods and heatshields combined with kerbin's shallow atmosphere. The only solutions I've found are to come in super shallow and try to bounce like apollo (only worked once or twice with the larger pods, maybe we could talk to the FAR people about how to give the heatshields and pods more lift), use wings (works fairly reliably but restricts your designs somewhat), or burn at about 30-35km until I'm under mach 5.

[ialdabaoth]

I've been having trouble with that regard, too. I think the problem may be the density of the command pods and heatshields combined with kerbin's shallow atmosphere. The only solutions I've found are to come in super shallow and try to bounce like apollo (only worked once or twice with the larger pods, maybe we could talk to the FAR people about how to give the heatshields and pods more lift), use wings (works fairly reliably but restricts your designs somewhat), or burn at about 30-35km until I'm under mach 5.

note that you don't have to wait until you're under mach 1. Parachutes are safe to open as soon as the reentry shockwave stops glowing, which is usually around 1000 m/s (around mach 3). You *can* do it at speeds of up to 1500 m/s, but you're taking a little bit of a risk.

[SchroedingersHat]

note that you don't have to wait until you're under mach 1. Parachutes are safe to open as soon as the reentry shockwave stops glowing, which is usually around 1000 m/s (around mach 3). You *can* do it at speeds of up to 1500 m/s, but you're taking a little bit of a risk.

With FAR you're often in fairly dense atmosphere by that time so your ship gets ripped apart by the extra drag; I think I need to work on reentry profiles a bit. One thing that may also help is a 2.5m heat shield with less ablative shielding (and less mass) -- my 1.25m reentry is fairly reliable.

[CAPFlyer]

The other option is to do a little modding and put a drag chute on your capsule like the real thing. The real capsules have at least 2 different sets of parachutes, not 1, so why should yours be any different? If you're using RT and have to "stage" the parachutes early, then all you need to do is create a new CFG and edit the automatic opening altitude for the chutes so that you arm them once entry interface begins and then they will deploy as you descend through the prescribed altitudes. The drag chute(s) should open somewhere around 20-25K, and the mains around 5-10K. You may have to mess with it a little bit to make it work right, but having the drag chute(s) will seriously help with your drag problem.

[Miller]

Is there any chance to make this great mod more compatible with FAR?

[ZobrAA]

Is there any chance to make this great mod more compatible with FAR?

It IS compatible with FAR

[earth]

it's compatible already!

[ZobrAA]

nuff said

[ialdabaoth]

nuff said

Funny you mention that! That is now fixed for 2.3 (to be released Monday unless people find more bugs for me).

Kerbals catch on fire around 500C and die at 900C.

[Frederf]

I've been having trouble with that regard, too. I think the problem may be the density of the command pods and heatshields combined with kerbin's shallow atmosphere. The only solutions I've found are to come in super shallow and try to bounce like apollo (only worked once or twice with the larger pods, maybe we could talk to the FAR people about how to give the heatshields and pods more lift), use wings (works fairly reliably but restricts your designs somewhat), or burn at about 30-35km until I'm under mach 5.

Shallow was interesting. My ablative shield was totally used up and the heat began to rise but did not exceed structural. I am trying to use a drogue-main chute pair but the default drogue doesn't want to stay on. Using capsule for lift is definately something I am trying but even at 25 AoA the lift is poor. If I came in steeper I might be able to use the extra speed-lift to climb but it would be harder to arrest the dive. I'm a bit surprised that pointy-end isn't a stable attitude which is useful but not realistic re Apollo.

[ialdabaoth]

I've found that if I'm reentering Kerbin, as long as my apoapsis is between 15k and 30k I do fine. This is with a mk2 pod, 2.5m shield, 3 side-mounted chutes and a shielded dock-o-tron on the nose.

[Moon Goddess]

Kerbals catch on fire around 500C and die at 900C.

I knew Kerbals were tough but 900C!!! Wow

[CaptainArbitrary]

So here's a thing. I just had a satellite blow up on ascent. The flight logger said it exceeded its g-tolerance, but some investigation revealed that it was taking heat damage at the time. The ascent profile was too aggressive, and the part heated up to about 510°C from friction with the air. With a max temp of only 600°C on that part, it weakened and finally failed.

Which is all well and good …*except the satellite was enclosed in a payload fairing at the time, one of the fairings from KW Rocketry. Shouldn't payload fairings shield parts from shockwave heating? Or are the KW fairings built in such a way that your raycast method isn't detecting them?

[Xechran]

Erm, about the "deadly" in the deadly reentry.

I recently had an unintended SCIENCE! opportunity. I was aerobraking in kerbin's atmo on a return trip from the Mun and came up just a few meters/second short of bringing the periapsis out of the atmosphere. I turned RCS on... only to find I had neglected to include a monopropellant tank in my build. I got my kerbal out to push... and ran him out of rcs fuel. At this point in the comedy of errors I switched back to the ship with the second kerbal on board and simply ran it into the ground. It didnt have a heat shield, but rotating and flipping it around was enough to bring it to the ground at 140 meters a second. Everything was still working before it splashed. Slowly asking myself, "Wheres the kaboom? There was supposed to be a Kerbal kooking kaboom!" I went back to the tracking center. Poor Archibald had separated from the craft enough that physics turned off and he was orbiting nicely at 60 km.

Determined to see at least some aerial fireworks tonight I loaded him up and watched his descent. Right clicked and brought up the temperature gauge to act as a kind of count down to Fun. -60c, 0c, 100c, 200c, 300c (wow still smiling), 400c, 500c, 600c, 700c, 800c, 900c, almost 1000c! Bastard is still grinning like the damn Cheshire cat, talk about keeping it cool.

Not only does he fly, he bounces?! I see now that much is fixed in 2.3 The part thats eating me is how well rotating the ship itself worked and why. The problem is that everything cooled off too quickly as it rotated away. Flipping end over end around 40 rpm the ship cooked up to about 700 only to chil down to normal as the section went retrograde. Is there a mod that alters heat retention/dissipation or a value somewhere I can alter to do so?

[foamyesque]

Couple of things; 2.2f.

1. I'm getting parts with two (occasionally different!) temperature readings;

2. When under direct lighting, the orange tanks look, uh, very peculiar.

Picture showing both issues:

EDIT:

Also, as a request: Radially attachable heatshields for the undersides of tanks and wings would be great.

Edited June 23, 2013 by foamyesque

[Frederf]

I'm hitting a wall (named Kerbin) trying to manage a reentry that manages to get slow enough for even a drogue deployment before getting too low in altitude. I've tried even a powered correction to maintain 30-40km artificially long, using canted capsule lift, and other such tricks without success. The only thing I can think of is to travel very fast and bury into the atmo deep enough so that the exit trajectory in a climb will mean I can decelerate going up and then back down. I doubt how survivable that is though. I probably just need to cfg edit myself a lower drag drogue that isn't 20G at mach 2 or so.

[foamyesque]

I'm hitting a wall (named Kerbin) trying to manage a reentry that manages to get slow enough for even a drogue deployment before getting too low in altitude. I've tried even a powered correction to maintain 30-40km artificially long, using canted capsule lift, and other such tricks without success. The only thing I can think of is to travel very fast and bury into the atmo deep enough so that the exit trajectory in a climb will mean I can decelerate going up and then back down. I doubt how survivable that is though. I probably just need to cfg edit myself a lower drag drogue that isn't 20G at mach 2 or so.

Are you using FAR?

Because I've found something interesting: FAR appears to be treating the headshields like a nosecone and applying minimal drag to them. Try taking the heatshield off-- the pod can survive without it, and will slow down muuuuuuuuuuch faster.

EDIT:

No heatshield:

With heatshield:

Pods and orbits otherwise identical. I would expect the additional weight of the heatshield to create a higher terminal velocity and slower deceleration, but note the hugely decreased Cd; it's identical facing forwards or backwards.

Edited June 23, 2013 by foamyesque

[SchroedingersHat]

I'm hitting a wall (named Kerbin) trying to manage a reentry that manages to get slow enough for even a drogue deployment before getting too low in altitude. I've tried even a powered correction to maintain 30-40km artificially long, using canted capsule lift, and other such tricks without success. The only thing I can think of is to travel very fast and bury into the atmo deep enough so that the exit trajectory in a climb will mean I can decelerate going up and then back down. I doubt how survivable that is though. I probably just need to cfg edit myself a lower drag drogue that isn't 20G at mach 2 or so.

For powered de-orbit I've found the best strategy to be wait until about 28km and burn retrograde -- that is if you can build something that will point that way with nearly-empty tanks.

Edit: Found a discussion of this type of thing on the FAR thread

http://forum.kerbalspaceprogram.com/showthread.php/20451-0-20-Ferram-Aerospace-Research-v0-9-5-1-Aerodynamics-Fixes-For-Planes-Rockets?p=333320&viewfull=1#post333320

May come back and see what it all means tonight.

Edited June 23, 2013 by SchroedingersHat

[BFGfreak]

Just a little FYI, the KW fairings don't exactly make the best heatshields.

What I guess happened was that the lower drag of KW's parts and the high drag of the heatshield resulted in my rocket wanting to fly nose first into Eve. Now this is all fine and dandy except that I'm guessing the gap between the fairing halves allowed my lander inside to get cooked and I lost the parachute before I had time to react and begin a panicked roll to distribute heat. I should say that my second entry burn into Eve went much better after I jettisoned the fairing halves and used the fairing base+heatshield part to shield the craft. And before anyone asks no I'm not using FAR, this is all stock aerodynamics.