Did Something Change with the Mk16 Chute?

[kinnerc]

Hi Folks:

New Kerbonaut, and first time poster.

Did something change or get patched on 27 Sept especially with regard to the Mk16 parachute?

I ask because I've been playing the game for about a week in career mode, normal difficulty. I've gotten semi-advanced rocket designs going right to the edge of 30 parts. I've gotten into orbit, successfully changed apogee and paragee, etc. Sure I've crashed a few times, but when that's happened it made sense.

One of the things I never, never, ever, EVER had problems with was re-entry and chute deployment. I'd re-enter, get heated up, not explode, slow down, pop the chute and land. Water. Land. Didn't matter. In three days it got so I could do this phase of the mission with my eyes closed. In fact, it got to a point where I said, "Yea, this game is pretty accurate, but I'm surprised re-entry is that easy."  Now, please remember, all of this was re-entry from low Kerbin orbit of, say, 70km when I didn't reach orbit, and 120km when I did.

Now, as of 27 September, suddenly, I can't successfully land at all. Whenever I try it, when I press the space bar to pop the chute, it either says that the chute has been destroyed due to heat and aero forces, or it pops up and sort of explodes with the module.

I've always manually deployed the chute (I say this because I'm getting the impression it can be automatically deployed based on ACL and altitude, but I've never tried that). 

I've checked my staging. 
This is unmodified Kerbal. The only settings I've played around with were tweaking the audio settings and changing the screen to full screen.

I've re-built rockets from the ground up (thinking there was an issue with that particular rocket), and I can't even do this now with a simple, single stage, SRB rocket.

My issue is that 2-3 days ago I could do this with my eyes closed. Suddenly I can't do it at all. The "destroyed due to heat and aero forces" had never come up.

Something has changed and for the life of me (or, in this case for the life of Jebediah) I can't figure out what.

Has anyone else experienced a sudden change in parachute deployment behavior? What can I check or change?

THANKS!
---
Doc Kinne

[Andiron]

Welcom to the forum !

When you de-orbit your craft, keep a slow descent with lowering your periapsis/perigee higher than 20km. If you go too steep in the atmosphere, the craft don't have time to brake and if you open the parachutes before slowing down to 250m/s, it will destroy it. There is a red/yellow/green indicator on the parachute staging showing if you can open it.

Edited September 28, 2016 by Andiron

[Aegolius13]

I would double check the chutes are not staged earlier.  The icon does not go away when they stage do you might not be noticing it.  

You can also try turning up the deploy pressure tweakable to .3 or so.  This will keep the chute from starting to deploy until you're lower, and probably slower.

[Gojira1000]

If you're seeing the chute mounting point pop-up on deployment and the capsule explode try adding a pair of drogues and deploy them prior to the Mk16. In 1.1.3 using Ven's I had some chutes institute RUDs when forces piled on too quickly. Only suggestion I can think of. I have NOT noticed this behavior in 1.2 at all

[kinnerc]

Gojira1000:

Drogue chutes make sense, but I'm not sure I have access to them yet. I only seem to have one parachute available (career mode), the Mk16.

Sorry, what is "Ven's," and what is an "RUD?" (I'm assuming an RUD is a drogue chute?)
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Aegolius13:

I have checked my staging; the chute is at the top all alone. I have looked at the chute tweakables, but have not changed them. The ACL seems to be set to .1, which I think is the default. Not sure what the altitude is set to because I've always manually deployed the chute without any problem. In fact, very early on I was deploying the chute at 5000m at one point thinking it would rip and it never did. It just remained thin until hitting 1500m then it deployed normally.

At this point I'm thinking of setting the ACL to .65 and the altitude to 1800m. Am I right that, absent any problems, once these things are set the chute should deploy automatically, or do I still need to hit the space bar?
----
 

Andiron:

Thanks for the welcome! I've been watching the chute icon, and I've seen it change colors, yes. Until things changed last night, it seemed to change from yellow to no color around 2000m and then I would hit the space bar to deploy it. now it doesn't seem to leave yellow until less than 1000m which doesn't leave time for a deployment.

In a suborbital hop you don't have a chance to angle your way into the atmo - you've never developed a high enough delta-V.

But again folks, the wierd thing is that there was a marked change in how the chute worked, suddenly, as of the night of the 27th. Deploying the chute suddenly became 1000x harder for me for no reason I can think of.

It is almost acting as if Kerbol has lost 90% of its atmo.  :/
----
Doc Kinne

Edited September 28, 2016 by kinnerc
Combining answers to questions.

[FullMetalMachinist]

1 hour ago, kinnerc said:

But again folks, the wierd thing is that there was a marked change in how the chute worked, suddenly, as of the night of the 27th. Deploying the chute suddenly became 1000x harder for me for no reason I can think of.

There has not been any update or patch to the released game since v1.1.3 came out in June. So that leave three possibilities for your troubles. 

1) You installed a mod that changed something, whether it was supposed to or not. I think you said that you're running stock, so probably not this, but wanted to be sure and mention it. 

2) You're doing something different, whether with your craft design or your piloting. Really only you can answer that. I would suggest loading a ship that you've flown successfully before, and fly it using the same flight path, and see if it still works. 

3) You've encountered some bug or some corruption with your game. First thing I would try is to go into your main KSP directory, and delete the file called "physics.cfg". This will force KSP to create a new file using the default values the next time you run the game. If that doesn't work, try a clean re-install. 

Hope this helps, and if it ends up being the craft design/piloting that's the issue, then screenshots definitely help to diagnose problems. 

[kinnerc]

FullMetal:

Thanks so much!

1) It is a stock game I'm running, yes. In fact, as I sit here, I don't even know how to install a mod yet.

2) I went back to old, simple ships (just a booster rocket) to see if that would put things back to how I had them before. No luck.

3) The deletion of physics.cfg sounds substancially promising. I'll do that when I get home, and then past that I'll try a re-install.

THANKS!
---
Doc Kinne

[Andiron]

2 hours ago, kinnerc said:

Sorry, what is "Ven's," and what is an "RUD?" (I'm assuming an RUD is a drogue chute?)

Ven's stock revamp is an awesome mod by @Ven which re-textures parts :

RUD is a KSP acronym of Rapid, Unplanned Disassembly, so a crash

Edited September 28, 2016 by Andiron

[Streetwind]

38 minutes ago, kinnerc said:

3) The deletion of physics.cfg sounds substancially promising. I'll do that when I get home, and then past that I'll try a re-install.

While you're at it, delete PartDatabase.cfg as well; it will automatically be recreated too. Whereas resetting the physics definitions makes sure the simulation runs as it is supposed to, resetting the part database makes sure that none of them (like the parachute) somehow got a broken drag definition that causes it to react the wrong way.

 

14 minutes ago, Andiron said:

RUD is a KSP acronym of Rapid, Unplanned Disassembly, so a crash

Not a KSP acronym, actually: it comes from realworld aerospace lingo You can also find it in variants like rapid unscheduled disassembly and such.

[radonek]

Early suborbital flights (until you learn to bend a gravity turn) tend to end very steep, which leaves you with little time to deploy chute safely. This is very dependent on flight profile, I guess you were just lucky. If you have big horizontal speed (like returning from orbit), you shed most of it in upper atmosphere (at about 18-25 km) and fall at about terminal velocity from there - with proper (or, more precisely, unproper) aerodynamics you may happen to reach safe speed at 8000m or even higher. If you just go up and spend a few minutes suborbital, you will fall almost straight down.  Watch your speed - that is critical for safe deployment. Do not rush it, it is perfectly ok to deploy at <2000m. Drogues certainly help, but should not be necessary.

RUD = Rapid Unplanned Disassembly, which is terminus technicus for "crash".

[HalcyonSon]

Try right-clicking the parachute in the VAB and changing the pre-deploy pressure to 0.75 and full-deploy altitude to 1,000 m.  0.75 should correspond to about 2000 m.  Then you can stage the parachute (spacebar) as soon as you hit orbit and not worry about it anymore.  As long as you don't re-enter at an extreme angle, you'll be below 250 m/s before the parachutes open.

These settings will cause problems if you come down in the mountains...  But most of Kerbin's surface is below 400 m altitude.

Edited October 3, 2016 by HalcyonSon

[Aegolius13]

3 hours ago, kinnerc said:

 

At this point I'm thinking of setting the ACL to .65 and the altitude to 1800m. Am I right that, absent any problems, once these things are set the chute should deploy automatically, or do I still need to hit the space bar?
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Chute deployment is a very non-intuitive three step process.  First, you have to arm the chute through staging.  You can do this manually, or in orbit.  The important thing is that you don't stage while ascending, for obvious reasons.

Next, the chutes partially deploy (visually pop out and slow the ship a bit).  This is governed by the pressure tweakable.  The default is very low, meaning if armed, the chutes will start deploying in upper atmosphere.  This usually destroys them.  Don't know why Squad chose such a bad default - it makes everyone ignore these settings.  The solution is either to wait to arm, or turn the number up.  Don't know if .65 would open too late; you'd have to test it.  Depends in part on reentry speed and angle. But this setting is unimportant if you always wait to safe speeds to even arm.

Third, the chutes fully deploy (spread out and slow you to landing speed).  This is governed by the altitude tweakable.  The default here is generally fine, though you can speed up landing by lowering it to 800m or so.

Sounds like your problem is linked to reentry speed, which is not something these settings would probably help with.

[kinnerc]

Folks:

Many, many thanks for the help today, folks!

It seems to be finally fixed. I ended up deleting physics.cfg on FullMetal's suggestion, but it did nothing. I then did a full re-install, saving my files before I did so.

Once the new install was done, I tried landing with my virgin copy and succeeded twice. I then put my files back into place and started my career game, redoing the mission that caused all the problems in the first place. Success!

I have no idea what caused the problem. It was like 80% of the atmo had been sucked from Kerbin. But it looks like I'm back.

Thank you again, folks!
----
Doc Kinne

 

[Chiron0224]

Welcome to the game Kinner!  I'm glad the issue was resolved for you.  One thing nobody mentioned, probably because we've all been playing for a while and didn't think of it, is that the parachute icon in your staging sequence is color coded.  So if it is red you are going to fast, orange you are almost there, once it turns to the normal grey button it is now safe to hit space and deploy the chutes.  This happens around 300 m/s surface speed.  Not sure if that's what was causing the trouble but it's something to keep an eye out for going forward.