F3D Skyknight

23 June 2017: I've added a discussion about the variations in the overhead hatch configuration here: http://tailspintopics.blogspot.com/2015/04/the-f3ds-of-flying-nightmares-in-korea.html

Paul Bless knows a lot more about the Douglas F3D Skyknight than I do and is generously sharing it. (Also see Steve Ginter's excellent F3D monograph here.)

First, there were three basic configurations: three XF3Ds (BuNos 121457-9), only 28 F3D-1s (BuNos 123741-123768), and the F3D-2s. There were also post-production mission modifications to the -2. A swept-wing -3 was initiated but cancelled by the Navy before it left the drawing boards. The F3D was redesignated F-10 in the 1962 designation system change mandated by DoD.

The XF3Ds had the very small engine nacelles, big speed brakes on the side of the aft fuselage, and a teeny tail bumper. They were powered by two Westinghouse J34 engines with a total thrust of 6,000 lbs.

For the production airplanes including the -1, the engine nacelles were significantly enlarged. According to one of the Service Test reports, "Weight and space provisions are made for the J34-WE-32, J34-WE-38, or J46-WE-2 engines, with and without afterburning." (It's not clear what dash number engines were installed in the production -1s or their rating. Depending on the source, they were -34s with a total thrust of 6,500 lbs or 6,800 lbs or -38s with a total thrust of 7,000 lbs, among others.) As Paul has pointed out, Douglas was also trying to interest the Air Force in the F3D as a substitute for its troubled F-89 at the time; this would have required installation of either the afterburning J-34-WE-15 or J-34-WE-17. Another change that affected the engine installation was an increase in the internal fuel capacity from 1290 gallons to 1350, which displaced the engines down and outboard slightly.

On the production -1, the size of the two existing speed brakes was significantly reduced and a large brake was added to the bottom of the fuselage, similar to the AD Skyraider installation. The latter proved to be unsatisfactory and was either not installed on or removed from the last 18 production -1s. The skid-type tail bumper on the XF3D was changed to a wheel-type tail bumper on the -1.

The roll control change between the XF3D-1 and the production -1s, which was an increase in the boost ratio from 15:1 to 20:1 proved to be inadequate. The -2s got wing spoilers for roll control in addition to the ailerons and for boost-off flight, an automatic mechanical advantage shifter providing a 2:1 ratio in lieu of the control stick extension feature which was also used on the F4D and the A4D.

Unfortunately, the F3D never got an engine with enough thrust so that its aerodynamic performance matched the capability of its night fighter avionics suite. There were very few deployments aboard aircraft carriers. Most of the F3Ds were operated by the Marine Corps from land bases.

The Korean War did provide a situation perfectly matched to its strengths, which was escort at night of Air Force B-29 bombers. In effect, the F3D crews were trolling for MiGs with the B-29s as bait. Even though the MiG pilots had no on-board radar, it wasn't as one-sided as you might expect because they were being vectored by ground controllers using radar and the F3D engine exhaust was very bright and readily visible at night. The F3D crew relied on their tail-warning radar to break away when a MiG came in behind them. The resulting kill ratio was seven MiGs and one probable against one F3D loss.

VC-33, the all-weather night attack squadron that provided detachments to air groups deploying on aircraft carriers to the Mediterranean and North Sea, evaluated the F3D as a replacement for the AD-5N, but determined that the Skyraider was more effective due to its much greater endurance and bomb/rocket carrying capacity.

The F3D was also valued for its size during the development of the air-to-air guided missile. The first one pressed into this service was the second XF3D.

This was followed by modifications of both -1s and -2s for testing by VX-4 and subsequently operational use by the Marine Corps. The -1M and -2M changes included removal of the 20mm cannons as well as a new, longer nose incorporating the Sparrow I missile control system. Although carrier qualified, none deployed with an air group aboard a carrier.

Paul also provided the following on the F3D-2B: "(It) was actually a series of modifications incorporated in approximately 114 (if I remember correctly) of the standard F3D-2’s to allow them to carry either the MK-7 or MK-12 special weapons... It was basically a two gun aircraft; removing two 20 MM weapons and armament components to allow for installation of the various ballistic and radar altimeter components required. The cockpit installations were all on the RO’s side of the aircraft. It also removed the tail warning radar and modified the right stores pylon to carry the weapons. The “pilot” aircraft for the modification was BuNo 127044, but I believe the intended plan was for the remainder of the aircraft to carry simply the F3D-2 designation (aka, nuclear capable F2H-3/4)."

Photo from Gary Verver

The Marines subsequently modified several F3D-2s, designated EF-10B, for electronic reconnaissance and countermeasures missions in the Vietnam War as a placeholder until the EA-6A was available.

Like the A3D, the size and relative simplicity of the F3D made it a very useful testbed. Three were taken up by the Army and used for test programs into the early 1980s.