Douglas F3D Skyknight

Former US Marine Corps Hornet pilot Louis Gundlach takes an in-depth look at the Skyknight

Former US Marine Corps Hornet pilot Louis Gundlach takes an in-depth look at the 'Night Killer' of the Korean War, the Douglas F3D Skyknight.

In 1945, the U.S. Navy was alarmed that the Japanese air force was building jet-powered bombers and kamikaze aircraft. The Navy's contemporary and planned propeller-driven fighters would be unable to intercept these extremely fast aircraft, especially at night. In response, the Navy put out a tender for a jet night-fighter that was to be equipped with an airborne intercept radar that could detect enemy aircraft out to 125 miles, an astonishingly demanding distance considering the then state-of-the-art. To put this into perspective, the detection of a small fighter out at 125 miles remains respectable in 2020! The Douglas Aircraft Company began work on a design built around the Westinghouse APQ-35 radar, which was actually a system made up of three radars. The main search radar, the APS-21, was equipped with a very large parabolic dish. This dish dictated that the nose of the aircraft would be very large. As well as being huge, the APQ-35 was also exceptionally complex and user intensive, so would require a dedicated Radio Operator. With these two design necessities in place, Douglas engineers designed a twin–engine aircraft with side-by-side seating. The aircraft became known as the F3D Skyknight.

The F3D-1 was equipped with two Westinghouse J-34 engines that each produced 3,400 pounds of thrust for a combined total of 6,800. While this was fairly good performance for a jet engine at that time, it wasn't much grunt for an aircraft with a take-off weight of 25,414 pounds. The engines were also canted down, away from the aircraft, which further reduced the effective thrust of the engines. With the added drag of a large nose, two-place canopy, and large straight wings, the F3D was easily outperformed by the day fighters of the time. It first flew in 23 March 1948 and was in service by 1951.

It could climb to over 40,000 feet and reach a true airspeed of 500 knots at that altitude (around sixty knots slower than its day fighter contemporaries). The aircraft had combat radius of 500 nautical miles and with drop tanks added it had a radius of 590 nautical miles. It was armed with four 20mm cannon. The aircraft’s performance was less than ideal, but it was purposely built to be a night airborne interceptor.

Like the Corsair in World War II and the Tigercat after the war, the Marine Corps came into possession of the Skyknight because of the type's inability to operate from aircraft carriers. Though the F3D was found suitable for carrier operations, it would require a whole host of modifications to ensure safe operation onboard a carrier. Additionally, since the Navy had given the Marine Corps almost all of the radar-equipped Tigercats, the Navy did not have Radar Operators or a programme in place to train ROs. The APQ-35 was found difficult to operate and maintain, especially on the cramped confines of an aircraft carrier. The Navy also had not adopted new procedures for jet aircraft to operate from straight-deck carriers at night. Lastly, the F3D was a night interceptor only. It could not carry any bombs during its early years and the Navy was pushing for multi-role aircraft even back then. In the end, the U.S. Navy did not have the expertise to operate the radar, fix the radar, and operate the large Skyknight around the carrier at night, so they gave most of the F3Ds to the Marine Corps.

APQ-35
The F3D was built around the APQ-35 radar system. This radar had four functions: to search for airborne targets; to compute a gun solution for the 20mm cannon;