and at high altitudes with excellent loiter time, the use of the pylon turn allowed the AC-47 to deliver continuous, accurate fire to a single point on the ground. In 1967, JC-130A 54-1626 was selected for conversion into the prototype AC-130A gunship (Project Gunship II). The modifications were done at Wright-Patterson Air Force Base by the Aeronautical Systems Division. A direct-view night-vision telescope was installed in the forward door, an early forward-looking infrared device was placed in the forward part of the left wheel well, with miniguns and rotary cannons fixed facing down and aft along the left side. The analog fire-control computer prototype was handcrafted by RAF Wing Commander Tom Pinkerton at the USAF Avionics Laboratory at Wright-Patterson AFB. Flight testing of the prototype was performed primarily at Eglin Air Force Base, followed by further testing and modifications. By September 1967, the aircraft was certified ready for combat testing and was flown to Nha Trang Air Base, South Vietnam for a 90-day test program. The AC-130 was later supplemented by the AC-119 Shadow (Project Gunship III), which later proved to be underpowered. Seven more warplanes were converted to the "Plain Jane" configuration like the AC-130 prototype in 1968, and one aircraft received the "Surprise Package" refit in 1969. The Surprise Package upgrade included the latest 20 mm rotary autocannons and 40 mm Bofors cannon, but no 7.62 mm close-support armament. The Surprise Package configuration served as a test bed for the avionic systems and armament for the AC-130E. In 1970, 10 more AC-130As were acquired under the "Pave Pronto" project. In the summer of 1971, Surprise Package AC-130s were converted to the Pave Pronto configuration and assumed the new nickname of "Thor". Conversion of C-130Es into AC-130Es for the "PAVE Spectre" project followed. Regardless of their project names, the aircraft were more commonly referred to by the squadron's call sign, Spectre. Recent and planned upgrades In 2007, AFSOC initiated a program to upgrade the armament of AC-130s. The test program planned for the 25 mm GAU-12/U and 40 mm Bofors cannon on the AC-130U gunships to be replaced with two 30 mm Mk 44 Bushmaster II cannons. In 2007, the Air Force modified four AC-130U gunships as test platforms for the Bushmasters. These were referred to as AC-130U Plus 4 or AC-130U+4. AFSOC, however, cancelled its plans to install the new cannons on its fleet of AC-130Us. It has