The wing was once part of the mod but has been removed because it no longer fit with our current standards. Worthy replacement(s) will come with Public 2.1.1x. IIRC an older version of the mod, namely Public 1.7.0a, is likely to still have it included. However, you are then missing out on the latest and greatest stuff and we can't provide support should you experience issues. Public 2.1.1x is planned for release on November 4th, 2021.