Naval Air Station-Joint Reserve Base Fort Worth, former Carswell Air Force Base and also home to a General Dynamics plant that was formerly owned by Convair and used to build the B-36 bomber.
@TimmyK, I know this is fairly old, but they pass through pretty regularly in the spring and summer. That 'UFO' sound is unmistakable and I the first time one came over the house, you can bet I was running for the back yard to see what the 'eff just came over!