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pquade

Kerbal Space Program 1.3.1 vs 1.4.1 Testing Mk2 Drag Differences

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I've noticed a HUGE difference in my Mk2 spaceplanes, but I wanted to make sure it wasn't something I was doing, so I made two identical craft in 1.3.1 and 1.4.1 and launched them with a launch testing script I adapted from the kOS tutorials.

The difference is huge and makes pretty much all of my Mk2 based spaceplanes no longer viable. I hope this gets fixed. I loved some of those.

Craft file here:
https://github.com/quade-ksp/KSP_Craft/blob/master/Testing.craft

kOS launch test script here:
https://github.com/quade-ksp/KSP_Craft/blob/master/launch_test.ks

Video here:

 

Edited by pquade
Added craft file and kOS script, wording.

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The video shows a vertically launched MK2 craft reaching apoapsis of 137km in 1.3.1, but only 38km in 1.4.1.  

I tried the linked craft in 1.4.1, and reached an apoapsis of 159km, so whatever the problem is, does not affect my install.   

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If it has a cargo bay, then that is likely the problem. It appears that cargo bays (and everything in them) produce crazy amounts of drag. 

Obviously a bug, and I believe there is a ticket on the bug tracker for it. 

Edited by MechBFP

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2 hours ago, MechBFP said:

If it has a cargo bay, then that is likely the problem. It appears that cargo bays (and everything in them) produce crazy amounts of drag. 

Obviously a bug, and I believe there is a ticket on the bug tracker for it. 

You can download the craft.  I linked it in the original post.

No cargo bay.
From nose to tail:
Mk2 Cockpit

Mk2 Drone Core, and the KAL 9000 (kOS)

Mk2 Rocket Fuselage

Mk2 to 1.25 Adapter, and 4 of the AV-R8 Winglets

LV-T45 Swivel

Still image
https://imgur.com/RjHuvCZ

2 hours ago, OHara said:

The video shows a vertically launched MK2 craft reaching apoapsis of 137km in 1.3.1, but only 38km in 1.4.1.  

I tried the linked craft in 1.4.1, and reached an apoapsis of 159km, so whatever the problem is, does not affect my install.   

Interesting.  As far as I can tell, both my 1.3.1 and 1.4.1 installs have completely stock career mode physics and difficulty levels.  I've never touched them.

Edited by pquade
Inserted still

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3 hours ago, OHara said:

The video shows a vertically launched MK2 craft reaching apoapsis of 137km in 1.3.1, but only 38km in 1.4.1.  

I tried the linked craft in 1.4.1, and reached an apoapsis of 159km, so whatever the problem is, does not affect my install.   

That’s a fairly big change!

 

So is it changes to the stock part files or changes to the way the game handles them?

 

Obviously the former could be easily fixed by copying the old part files across but the latter will be trickier.

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1 hour ago, pquade said:

You can download the craft.

I downloaded the craft and found no differences between 1.3.1 and 1.4.1.

The new craft assembled in 1.4.1 also has no differences.

 

Edited by Marschig

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7 hours ago, Marschig said:

I downloaded the craft and found no differences between 1.3.1 and 1.4.1.

The new craft assembled in 1.4.1 also has no differences.

 

Facinating.  Can you help me figure out what the difference in my game might be then?

As far as the parts and physics go, I believe I'm running 100% stock.

Is there some physics setting I ought to be looking out for which might explain the issue?

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I've had similar issues with some aircraft parts. Some of the MK2 and Size 2 (Airplane Plus) parts have, from what I can observe, no shielding from the atmosphere, especially when loading up with passengers. A plane that can do 500+ m/s empty struggles to do 250m/s when loaded up with 40 passengers.

But most rocket parts don't seem to be affected, at least the one's based on old designs.

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To the people who have downloaded the craft and run their own tests, what Ap are you getting closer to; 38,500m or 137,000m?

I'm trying to figure out which of my results are closer to yours where you're seeing no difference between 1.3.1 and 1.4.1.

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1 hour ago, pquade said:

Facinating.  Can you help me figure out what the difference in my game might be then?

As far as the parts and physics go, I believe I'm running 100% stock.

Is there some physics setting I ought to be looking out for which might explain the issue?

There are many mods in your video. Try really 100% stock.

38,500m or 137,000m

To 137000m.

 

Edited by Marschig

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1 hour ago, pquade said:

To the people who have downloaded the craft and run their own tests, what Ap are you getting closer to; 38,500m or 137,000m?
 

Launched your test craft vertically in 1.4.1 and it reached ~42km with an Ap of ~170km when it ran out of fuel. 

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Trying now with a 100% fresh install and getting similar results.

Maybe a mod that's causing the issue.

Now experimenting one-by-one to see which it might be.

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Okay, mystery solved!

Turns out it was Kerbal Planetary Base Systems v1.6.1.

I'll be notifying the Nils277 of the results.

My apologies to the gang at Squad for assuming it was them and I'll be removing the video.

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Moving to technical support for modded installs.

Glad you got it sorted out.  :)

 

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