One of the most mysterious aircraft ever was the virtually undetectable F-117 Nighthawk, designed by Lockheed's “Skunk Works” team from their Advanced Development Projects Lab. The airplane's very existence remained denied and classified until six years after active duty. Its unique shape was engineered to avoid deflect radar detection, while its wings and fuselage were coated with radar-absorbing materials. In 2023, the Air Force tested a daylight variant they called, “The Gray Dragon.” Painted in two-tone gray, it would be less detectable to enemies during daytime flights than typical jet-black Nighthawk.