Parachutes explode on re-entry

[RCgothic]

Since coming to 1.02 after a bit of a break from 0.9, I've been having a problem with my parachutes exploding BEFORE deployment (ie at around 30km whereas I'd usually deploy around 10km and <500m/s.)

I first noticed that the radial chutes were exploding no matter where I put them, but recently nose cone chutes have been exploding as well. Atmospheric heating is turned up to 1.2x.

I figure what's happening is that the pod is heating up to above the endurance limit of the chutes, but I'm at a loss as to how to prevent it. I've got a heat shield, and in other respects it seems to be doing its job. Pod is correctly oriented with heat shield prograde. Any ideas? Luckily Jeb and Val have both survived bailing out several times, but I'd quite like to be able to land properly.

Set up is: Mk1 Pod, nose chute, heat shield. Re-entry from 80km apoapsis to 30km periapsis.

Edited June 21, 2015 by RCgothic

[ElWanderer]

Are you staging the parachutes before re-entry? The default semi-deploy pressure will trigger them in the midst of the flames if they have been staged... tweaking that setting to something much higher (0.25-0.5) means they'll pop out much lower. If you have just a chute, pod and heat shield and you are flying shield to prograde (which happens by itself with SAS off), it won't be heat transference.

[Jart]

Shield external parachutes with fairing.

Or go low tech put 1 or 2 in a storage container. Just remember to get the doors open.

[RCgothic]

No, the parachutes are very last in the staging and are not deployed when they explode. To clarify, it's the casings that blow up with the chutes still in their boxes. And I am flying heat shield prograde.

I'm currently tier 1 science with only all the 45 Science unlocked.

[cephalo]

I find that I have to put radials on a reverse slope to be sure they won't explode. if I can't do that I use the next size ablator.

[FancyMouse]

That was weird. Even in this experiment of mine, chutes are never close to getting exploded (while some other parts start exploding quickly). Of course, one thing that you need to note is - you need to do a retrograde reentry. If you do prograde, then your chute is likely to get more air friction and get a lot more heat. Although I've not seen one single case of chute explosion due to prograde reentry during my gameplay. You probably want to enable heat debug and then give us a picture of the heat flux for your chute to figure out what's going on.

[ElWanderer]

No, the parachutes are very last in the staging and are not deployed when they explode.

Hmmm, you mean the whole part explodes/vanishes? :/

What does the F3 log say after the chute has gone? It should tell you if a part has been destroyed by heat. If it's not saying that, I'm pretty sure it's because they are semi-deploying. I don't think the log tells you when an exposed chute or extended solar panel is burnt off. If it does tell you that it is the heat destroying the whole part, then that would be weird*, but at least it's not down to the staging!

If you hit alt+F12 -> thermal tab, there is an option to add the temperature details to the right-click parts menu. Then in flight you can right-click on parts to see how hot they're getting. I can't remember what the heat tolerance of the chutes is, but that can be looked up in the VAB.

* given how gentle re-entry heat is, even at 120%, from an 80km by 30km orbit.

[FancyMouse]

Well I think OP is saying what he's seeing, and I don't think he staged/deployed the chutes - if it's because the chute semi-deployed, it won't explode - just chutes being cut off from what I remember. But yeah better show some pics and preferably with the thermal debug option on.

[Mic_n]

Seems pretty clear that he's talking about the parts exploding, which would be good old re-entry heating. An inline chute on a nosecone (if you're pointing prograde for some reason like your aerodynamics mean you have to be) is going to take the brunt of the heat.. if it's attached to a capsule which is also building and radiating heat, it'll get some of that, too. Radials stuck on the sides are in the airstream and thus face the same problem.

So yeah... don't come in so damn fast. Depends on your orbit.. if you're in LKO, drop your Pe to maybe 40km or so, no further. A nice shallow dip into the atmosphere gives you plenty of chance to bleed off speed over a longer time, so the stress isn't nearly so much. Coming from higher out, keep it higher up.. you might need to make a few passes in and back out of atmosphere, but you'll get there. If you want to get a precise landing spot, you might want to make a little correction burn once your Ap is down a bit lower to bring your Pe to a better spot..

I'm still trying to work out why so many people seem to be having re-entry problems now.. are people just burning back from the Mun and trying to drop straight onto the KSC or something? Yeah, that's not gonna work real well.

Edited June 14, 2015 by Mic_n

[OddFunction]

I have the same problem.

I solved it like this:

Strut Placement 1 & 2 - Goal is to prevent FAR from ripping service bay from pod

http://i.imgur.com/zINfWyh.jpg

http://i.imgur.com/mJXiW8I.jpg

Heatshield Placement

http://i.imgur.com/UhCpvKD.jpg

View of service bay without chutes:

http://i.imgur.com/pyCpqyw.jpg

View of service bay with chutes:

http://i.imgur.com/ULstCwv.jpg

If you make a ship like this, you will survive ninety nine percent of your re-entries... except vertical ones, of course. I use FAR and RealChutes so I have lost many Kerbals to chutes ripping off... this has been my solution.

Note if you have tweakscale, you can make the probodyne core + chute placement much, much nicer.

[tomf]

What colour are the parachutes in the staging display (bottom left) immediately before they explode? And do they have full overheat bars in the thermal overlay?

[RCgothic]

Ok, I had another mission go south and got a few pics. This is from a Mun return mission, but it survived the first two passes alright. I suspect the third pass came in too steep, but there wasn't a huge amount I could do about that. In any case I don't think a parachute should be blowing up under these circumstances.

[imaspacestation]

Looks like you're using FAR? And Real Chutes?

[RCgothic]

Amongst others. I'm using Deadly Reentry too, though my understanding is that's basically been reduced to a parts mod. But I was using FAR and Realchutes before I made the switch from 0.9 to 1.02 without issue, so I figure it has something to do with the new version.

[DancesWithSquirrels]

Looks like the numbers for FAR/RealChutes (could be either/both) are unreasonable, making the RealChute cone parachute too sensitive to heating. Try using the stock parachute and see what happens.

[RCgothic]

It also happens with stock chutes. I've also had the KER module blow up inside the service bay on a few occasions.

[Mic_n]

I'm noticing my probe cores (happily tucked inside service bays) starting to overheat.. All I can think is that they're having heat conducted in from the Mk2 tanks/lifting surfaces (which seem perfectly fine), through the service bay, and into the probe core. It's the first thing on the vehicle to throw out a heat bar and it's _supposed_ to be tucked safely inside the body of the thing.

I'd love to see some way of adding some insulation or something, it's really quite annoying.

[MaverickSawyer]

I'm noticing my probe cores (happily tucked inside service bays) starting to overheat.. All I can think is that they're having heat conducted in from the Mk2 tanks/lifting surfaces (which seem perfectly fine), through the service bay, and into the probe core. It's the first thing on the vehicle to throw out a heat bar and it's _supposed_ to be tucked safely inside the body of the thing.

I'd love to see some way of adding some insulation or something, it's really quite annoying.

Yes, there is thermal conductivity. I've had the same issue of overheated components in the holds of reentering spaceplanes.

As for insulators... Nertea's nnew Heat Management mod has 1.25,2.5, and 3.75 meter inline insulators. I suspect that a .cfg edit of, say, a TT-38K radial decoupler, to make it a radial insulator may be in order for now to help mitigate these kinds of issues.

[imaspacestation]

Reason I ask about FAR is because this is not the only (there are tons of these) posts about parachutes blowing up from re-entry, and often times the person has FAR installed.

Can you try re-entering with the exact same ship with roughly the same speed and attitude, but with FAR and real-chutes disabled? If it works without a hitch, then you will know the issue lies in either of these two mods.

[RCgothic]

I think uninstalling DRE fixed the problem. Just survived a Münar re-entry without issue and the heat shield seemed to be ablating properly. I'm not a masochist; I wanted re-entry heat, not ultra-death mode. Now that stock has added that DRE seems to cause more issues for me than it solves. It doesn't work at all like it used to.

[Mic_n]

After poo-pooing the "what's everyone complaining about with this heat stuff?".. I've now unlocked the Mk3 spaceplane parts and ...? Even just launching these things are getting scary hot, still building heat up and cooking my probe core in its service bay at >30km while accelerating to orbit. Coming back down, nice and slow and never ever "flaming up", and still every single part gets a temperature gauge showing up on it. This is madness!

[mrclucks]

Amongst others. I'm using Deadly Reentry too, though my understanding is that's basically been reduced to a parts mod. But I was using FAR and Realchutes before I made the switch from 0.9 to 1.02 without issue, so I figure it has something to do with the new version.

DRE is most definitely your problem. I'm able to reenter with a PE around 35 as long as I'm below munar height and have a heat shield of equal or large diameter as the other parts and easily survive. This is in normal mode and I lose a few ablator from lko and about 20 from munar return

[Sharpy]

Other options.

1. A.I.R.B.R.A.K.E.S. - they really make the reentry a breeze, especially with a flat trajectory (deorbiting, not "dive") - just deploy them above 60,000.

2. Get some fins on the front and maneuver your rocket to enter the atmosphere sideways. The huge drag it creates really sinks speed fast.

3. Powered braking. Turn retrograde and burn. Also, even without this, your nose parachute should be safe (but your engine may explode).

[RCgothic]

Problem was fixed by uninstalling DRE. Something to do with parts heating up in proportion to their mass, so that small parts get hotter than large ones.

Anyway, uninstalled and all now behaving as it should.