[support] Fairings produce way too much drag

[Nachbar]

KSP Version: 1.4.2.2110 (WindowsPlayer x64) en-us

What Happens: Fairings produce an exceedingly high amount of drag

Mods / Add-Ons: none. Fresh install

Steps to Replicate: Build 2 rockets of similar size/weight and have one of them use a nose cone and another use a fairing

Result: The rocket with the fairing goes about 1/4 the distance compared to the one without

Fixes/Workarounds: don't use fairings?

Other Notes/Pictures/Log Files: Here are 2 example craft that I made to test with: https://drive.google.com/open?id=1MCIuAVxSSUg6OewV04_zFVf9HcR2O_Hl and https://drive.google.com/open?id=1rgqZnOxIuiXVC9fm0PUFAkZB8jSgcoLu

The example rocket without fairings (TEST) will go to about 520km straight up with sas enabled. the one with fairings (TEST 2) will only go to 130km 

Screenshots: https://imgur.com/a/E49jC

This is my first bug report let me know if there is anything else I should be providing.

Edit: I figured out how to add this to the bug tracker.

Edited March 28, 2018 by Nachbar

[JimmyR]

3 hours ago, Nachbar said:

KSP Version: 1.4.2.2110 (WindowsPlayer x64) en-us

What Happens: Fairings produce an exceedingly high amount of drag

I have noticed this as well. I tried to add my own screenshot and test craft to your issue in the bug tracker but I'm not sure if it went through.

screenshot

[Squelch]

We are currently looking into this, and thank you for the detailed issue report on the bug tracker to you both @Nachbar and @JimmyR

[Rocket In My Pocket]

Well, the drag numbers all look fine, they are all the same anyways; I don't think they've changed at all.

    maximum_drag = 0.2
    minimum_drag = 0.2
    angularDrag = 2

To be fair most of the Nosecones have way better numbers than this:

    maximum_drag = 0.1
    minimum_drag = 0.1
    angularDrag = 0.5

Only other difference I can see (I could be way off, just throwing ideas out there) Is some of the fairings are missing the line: partTypeName = Fairing

MODULE
    {
        name = ModuleCargoBay
        DeployModuleIndex = 0
        closedPosition = 0
        lookupRadius = 0.75
        partTypeName = Fairing
        
        // nodeOuterAftID = bottom
        // nodeInnerAftID = top
    }

Also the "lookupRadius" (Which I assume tells the game what diameter to shield parts from aero drag?) is also a bit odd in places, like the Size 3 and Size 4 both have 2.5?

Again, this could all be meaningless, I'm just an amateur after all.

Edited March 29, 2018 by Rocket In My Pocket

[EvenFlow]

Without going into much detail as Nachbar and JimmyR seem to have provided enough evidence already I can confim that fairings seem to produce extreme amounts of drag in the current patch.  Some of my spaceplanes which use fairings seem to be producing disproportional amounts of drag. Screenshot of the same craft with and without fairings at comparable speeds and altitudes:

EDIT: I can also confim that this behavior seems unique to the current patch. The planes I mentioned were tested
in previous patches and could achieve higher speeds (these drag artifacts were not present back then.)

Edited April 1, 2018 by EvenFlow

[LameLefty]

This might explain why MechJeb can't land my fairing-encapsulated heavy rover payloads on Laythe very accurately (they tend to undershoot the target by anywhere from 1 - 3 kilometers, depending on the mass of the encapsulated payload and the exact starting trajectory.

[Grommen]

Two more things of note:

EJ of EJ_SA on Twitch noticed that the drag on the part behind the fairings is also getting a far too much drag as well.  In many cases a fuel tank has two times the co-efficient drag of a flying brick.

Not sure if this is gonna cause trouble but :

https://www.twitch.tv/videos/245164428

He finds is about 4:16:00 in that video.

Secondly if the faring is loaded from a save and then launched (I'm assuming a sub assembly, merged etc).  The problem with drag occurs.  However if you completely remove the faring and add in a new one building it just like the one loaded from the save.  The drag on the part drops to zero and never changes during launch.  The part below it however gets crazy drag as before.

Hope this helps...

[Nachbar]

If you deploy the fairings on my test craft and then launch it it will ascend to roughly the same height as the one before except that it will tumble in the atmosphere once it runs out of propellant.

 

My guess is that the fairings are not reducing drag at all but at least they are keeping the drag uniform.

[RayVanl]

I have noticed, when adding fairings in 1.10 stock (other than KER) that when you have the engineering report open, fairings are shown as excessively wide (like, 1.8m instead of 1.3) until you close and reopen the engineering report. Definitely a bug, and if the miscalculated value is actually used during flight it would cause major issues with generated drag.

[Serenity]

1 hour ago, RayVanl said:

I have noticed, when adding fairings in 1.10 stock (other than KER) that when you have the engineering report open, fairings are shown as excessively wide (like, 1.8m instead of 1.3) until you close and reopen the engineering report. Definitely a bug, and if the miscalculated value is actually used during flight it would cause major issues with generated drag.

Does that weirdness comes only if you have the engineering report open?

Have you tried opening it up for first time after loading the craft, because hopefully its just a refresh bug from the mod.

Edited August 12, 2020 by Boyster