I'm guessing that this superconductor concept hasn't actually been reduced to a prototype. Unfortunately, per the USPTO, "[a]n applicant need not have actually reduced the invention to practice prior to filing." https://www.uspto.gov/web/offices/pac/mpep/s2164.html#d0e215... A patent can simply describe a so-called prophetic example. "A prophetic example describes an embodiment of the invention based on predicted results rather than work actually conducted or results actually achieved." Id.
EDIT: Yep. The abstract from this 2019 paper, "Room Temperature Superconducting System for use on a Hybrid Aerospace-Undersea Craft", clearly (IMO) says the concept is as-yet unconfirmed. https://arc.aiaa.org/doi/abs/10.2514/6.2019-0869
Also, what are fair and usual terms to use a government-owned patent?
I don't think the [notorious] Bayh-Dole Act (https://en.wikipedia.org/wiki/Bayh%E2%80%93Dole_Act) applies as it seems the inventor is an actual DoD employee (Naval Air Systems Command/NAWCAD, NAS Patuxent River), not a scientist at a private institution receiving government funding.
