Weird MKS inflatable parts aero shielding behavior after USITools update

[Wyzard256]

A recent change to USITools.dll seems to have changed the conditions for the MKS Ranger inflatable parts to receive aerodynamic shielding from a payload fairing. Unless the fairing is very large, the inflatable parts won't receive aero shielding, and will produce drag during atmospheric flight even while "inside" the fairing. This can make it difficult to launch a rocket whose payload includes radially-mounted Ranger inflatables, e.g. on the base of a Scout landing module.

Here's a .craft file that has a Ranger mini-hab inside a payload fairing. With a clean install of MKS v0.50.13 (including USITools.dll v0.8.11) or v5.0.12 (including USITools.dll v0.8.10), the hab doesn't get aero shielding from the fairing. (Place it on the launchpad, turn on the "aero data in action menus" debug option, then zoom the camera through the fairing and right-click the hab. It says "Shielded: False" at the top of the menu.)

However, if you go back to the VAB and make the fairing a full segment taller, keeping the same diameter, then the hab does get shielding. The other MKS inflatable parts behave similarly, though the required fairing size (both diameter and height) varies.

Note that if you inflate the hab, it sticks out through the side of the fairing — yet it still gets aero shielding from the "tall" fairing, so the shielding check clearly isn't based on the size of the inflated hab dome in its displayed orientation. However, the tall fairing is big enough to fit the inflated hab dome pointing upward, so it could be that the shielding check is looking at the inflated size in the wrong orientation.

If you replace USITools.dll with v0.8.8 (from USI Core v0.3.4), the problem goes away and all the Ranger inflatable parts receive aero shielding from the original "short" fairing.

(As a workaround, the inflatable part can be placed inside a KIS SC-64 container. Those can be attached anywhere a Ranger part can, and after BobPalmer/MKS#1112, they're compatible with the Scout's weight transfer feature just like the Ranger parts are.)