Upside-Down Fairing Not Working

[Aegolius13]

Hey folks,

I recently tried using an upside-down fairing as an improvised adapter for some big fuel tanks.*  It did not work so well - the tanks were generating enormous amounts of drag, as if they were not being shielded at all.  I reproduced the problem in the simplified test shown in the pic below.  I have three identical fuel tanks, with three identical nose cones - the only difference is the middle stack has a fairing between cone and tank, and the outer stacks have 3.75m to 2.5m converters.  

As the pic shows, the tank under the fairing is generating over 10 times as much drag as the one behind the adapter.  The leads me to believe that, for whatever reason, upside down fairings do not work to provide a low-drag transition between form factors.   

Anyone know what's going on here?  Is this just a consequence of the game's code - the part is written so that the drag reduction effect is directional?  Or is there some different way to do this so that it works correctly?

(*In case you're wondering why I'm doing this in the first place, I'm playing a modded career game and trying to launch a mining ship with 5m Near Future fuel tanks.  I don't have an adapter that big unlocked yet, but I can get the necessary coverage with an upside-down fairing.  The issue does not seem Near Future-specific, however, since the test pic is using only stock parts).  

[Foxster]

Its not easy to tell what you have there from the one dark picture.

However, a common issue in these circumstances is the length of the fairing. It not being enough for the fairing to cover just the gap, it also needs to extend over a certain amount of the tank below the gap, sometimes nearly all of it. 

[Pand5461]

Noticed this fairing behavior too. Something hardcoded into the game, I suppose.

FAR makes fairing work properly. But it changes the aerodynamics overall so any atmospheric craft you already launched may become unstable.

[bewing]

What version are you running? The QA team has taken a couple whacks at reproducing your issue in the current version, with no luck. We will look a bit more.

 

[Aegolius13]

7 hours ago, Foxster said:

Its not easy to tell what you have there from the one dark picture.

However, a common issue in these circumstances is the length of the fairing. It not being enough for the fairing to cover just the gap, it also needs to extend over a certain amount of the tank below the gap, sometimes nearly all of it. 

In the original, I extended the fairing to the top of the tank, where you first get the blue "close fairing" text.  But I re-tried with a fairing that extends wider than the tank, and wraps around the top of it, and get the same problem - see pic below.  I am also actually getting huge drag with this fairing too; not sure if it's because it's wider and blunter of if there's something else going on.  

 

 

4 hours ago, bewing said:

What version are you running? The QA team has taken a couple whacks at reproducing your issue in the current version, with no luck. We will look a bit more.

 

1.3.1.1891.  I've tried it on both my Galileo and regular games.  Not running any mods I would expect to affect aerodynamics.  

[Pand5461]

4 hours ago, bewing said:

What version are you running? The QA team has taken a couple whacks at reproducing your issue in the current version, with no luck. We will look a bit more.

 

This is reproducible with 1.3.1.1891 on Linux as well.

I have a simple craft made from OKTO probe core, basic nose cone, 1.25 m fairing, Flea booster and 3 basic fins. Max altitude is massively different depending on whether the fairing base is below or above the probe core.

Fairing going up:

Upside-down fairing:

The first design goes up 20-ish km, second one 4-ish km.

With the deleted fairings, both designs perform roughly identically, reaching max altitude of 4-something km.

[bewing]

4 minutes ago, Pand5461 said:

I have a simple craft made from OKTO probe core, basic nose cone, 1.25 m fairing, Flea booster and 3 basic fins

Thanks, that will definitely help in testing.