Vought's Not-So-Fearsome F6U Pirate

In September 1944, the US Navy gave eight aircraft manufacturers a shot at a contract to build its first carrier-based jet fighter. The Navy relaxed its usual carrier and landing takeoff limitations as much as was practical in order to "obtain the highest possible performance for a carrier-based VF type." Of the eight companies approached, four of them submitted designs- Grumman, McDonnell, North American, and Vought. Douglas was already working on the Navy's D-558 Skystreak research aircraft program and therefore didn't bid. The Navy selected three of the companies to build their designs in order to spread out the risk amongst several approaches. Grumman, to everyone's surprise, didn't make the cut. Grumman's submission was felt to be too close and similar to Vought's submission and thus represented a duplication of effort (this same reasoning led to Boeing's Light Weight Fighter, LWF, submission to be disqualified in the 1970s as it was too similar to the General Dynamics submission which became the F-16). The Navy justified this as Grumman was much busier with the coming F7F Tigercat and F8F Bearcat programs while Vought only had the F4U Corsair program which would be winding down wit the end of the war. 

McDonnell's submission became the FD-1/FH-1 Phantom and would be the first carrier-borne jet fighter to go into service with the Navy. North American's submission became the FJ-1 Fury, and Vought's design, the one which we'll focus on in this post, became the F6U Pirate. The Pirate along with the Fury wouldn't have folding wings, instead those jets had an auxillary nose wheel which was inserted into a socket under the nose. The nose wheel was then retracted and the plane "kneeled" forward. This allowed the nose of another aircraft to be parked under the tail of another to compensate for the lack of folding wings. 

Built and designed at Vought's main facility in Stratford, Connecticut, it was powered by a single Westinghouse axial-flow J34 engine. Since the J34 was much slimmer than the J33 used on the Fury, the Pirate had a very slender fuselage by comparison to the other single engine design, the Fury. Because the J34 engine was felt to be still-experimental, only taxi runs were performed in Connecticut and the F6U prototype was disassembled and flown to Muroc Army Air Field (later it would be named Edwards AFB) in California for its first flight. It wasn't a good start- 24 minutes into the maiden flight on 2 October 1946, the accessory drive failed and the test pilot, Ted Owens, had to make an emergency landing on the lakebed. The flight test team had to wait 45 days before Westinghouse could provide another engine. Despite other technical issues cropping up in the flight test program, the Navy went ahead and issued an initial production contract for 30 F6U fighters along with contracts for the Phantom and Fury. And this was before the flight test program at Muroc uncovered even more programs with the Pirate- first came the discovery of very unpleasant stall characteristics. Then as the F6U approached Mach 0.6, the rudder began to demonstrate buffet issues. Once this was resolved and the flight envelope was expanded further, the poor longitudinal stability of the Pirate gave it unacceptable Dutch roll oscillations in flight. This resulted in several modifications to the tail unit and aft fuselage. But worst of all, the F6U was woefully underpowered- it had the same equipment (pilot, cockpit, guns, avionics, etc.) as the FH-1 Phantom's immediate successor, the F2H Banshee, but only 1/2 the engines. Whereas the Banshee used two J34 engines, the Pirate had only one. Vought's solution was to incorporate the first jet engine afterburner on a production aircraft, but this added weight and required further rework of the Pirate- something not made any easier with the flight tests taking place in California and the engineering located in Connecticut. To further worsen matters, the afterburner wasn't fully reliable, not always lighting when commanded.

With the Pirate program now approaching two years behind schedule, Vought decided to move the entire program to Grand Prairie, Texas, at NAS Dallas. Many of Vought's engineering and production staff refused to move to Texas and this further exacerbated the delays in the F6U Pirate program. To make matters worse, it was discovered that the main runway at NAS Dallas wasn't long enough for the F6U Pirate and it had to be extended further out into Mountain Creek Lake. While this was being done, the first production F6U Pirates were flight tested at Carswell AFB in Fort Worth starting in June 1949. This didn't sit well with the USAF and the biggest non-military tenant at Carswell, Convair. To avoid further conflicts, the flight testing then got moved again, this time to Ardmore, Oklahoma, at what would later become Ardmore AFB. By the time Vought managed to make the first flight of the first production F6U Pirate, it should have had all 30 of the first production order already delivered to the Navy. By this point, the successor to the FH-1 Phantom was already entering service, the McDonnell F2H Banshee and the first Grumman F9F Panthers were also entering service. By October 1949 only two production Pirates had been accepted by the Navy. By February 1950, Vought managed to deliver all thirty of the contracted F6Us- most of them were stored with VX-3 and then parceled out to various Navy testing facilities. No attempt was made to even carrier-qualify the Pirate- the thirty production aircraft only flew a sum total of 945 hours and most of the aircraft had less than 10 flight hours- enough for a production flight acceptance test flight and a ferry flight to its final disposition.

The go-ahead for production for the Pirate surprised many in the Navy. It was either a case of Navy sympathy for a long valued supplier and as a possible back up for the Grumman F9F Panther program. But whatever the case may be, the Vought F6U Pirate was too little, too late and a shock to many observers given Vought's long history of successful carrier aircraft up to that point. It was a learning experience for Vought that they applied to their next carrier fighter, the F7U Cutlass, which ended up being just as troubled. Caught on the ropes, Vought finally got the carrier-borne jet fighter right with its third try in the form of the F-8 Crusader.

Source: U.S. Naval Air Superiority- Developement of Shipborne Jet Fighters 1943-1962 by Tommy H. Thompson. Specialty Press, 2008, p35-49.

How the Lockheed P-80 Saved McDonnell Aircraft

In 1942 James McDonnell was summoned to Washington to meet with officials from the US Navy's Bureau of Aeronautics (BuAer). At the time McDonnell Aircraft only built parts for other aircraft manufacturers at its St. Louis facilities and only had one aircraft program going, the XP-67 Moonbat fighter. To McDonnell's surprise, BuAer asked McDonnell and his small team to design a carrier-based jet fighter. Not having had any prior experience worked in McDonnell's favor- the Navy felt that he was free of any bias or prejudices and was therefore most likely to come up with an innovative design. McDonnell's design would be come the FD-1/FH-1 Phantom, the first purpose-built carrier-borne jet fighter. But BuAer's decision was not without its controversy in the Navy and to satisfy the critics, it was agreed to evaluate an existing jet fighter that by that point was only a year from its first flight- the Lockheed P-80 Shooting Star, which first flew in June 1944. With a more powerful engine, the P-80 was faster than the FD-1 Phantom. In early 1945, the Navy purchased two P-80 Shooting Stars for evaluation, one of which would be suitably modified for evaluation as a carrier-borne fighter. 

The first Navy P-80 was flown from Lockheed's California facility to the Navy's flight test center at NAS Patuxent River, Maryland, incidentally becoming the first transcontinental jet flight on 29 June 1945 (though it wasn't a nonstop jet flight). The pilot was a young 1st Lt. Najeeb Halaby, at the time a US Navy test pilot who later on would become the FAA Administrator under JFK and later become CEO of Pan Am. The plan was to conduct shore-based trials first before going through with ship-board trials. Through 1946 the P-80 was flown in mock combat against the Navy's main fighter of the day, the Grumman F8F Bearcat. Though not as maneuverable as the Bearcat, the P-80 had the luxury of speed to engage and disengage in combat much to the Bearcat pilots' frustration. The second P-80 arrived at NAS Patuxent River in December 1945 after being modified by Lockheed with a tailhook, catapult hooks (for use with a catapult bridle) and a catapult shuttle holdback. Shore-based tests to simulate carrier operations were used to determine the operating parameters for the P-80 on the carrier deck. Catapult shots were easily accomplished on land-based gear, but it was found that the P-80 was exceptionally clean aerodynamically on approach and had to be "flown" onto the deck, but the nose gear design was too weak for a firm carrier-style three-point landing. But if the P-80 landed to hard on its mains, it would rock forward and the hook would miss the arresting wires. 

After more testing, the project pilot, the legendary Marine Corps ace Lt. Col. Marion Carl and his LSO managed to determine the proper approach speed (just 5 mph above the stall speed of the P-80) and flare to minimize the forward rocking motion on landing. Though the margin was considered too close to the stall speed, Carl found that the P-80 had good stall warnings well in advance of the actual stall. On 1 November 1946 Carl took the P-80 to sea aboard the USS Franklin D. Roosevelt. Catapult launches and arrested landings were made safely, but it was found that the P-80 needed 900 feet of deck with 35 knots of wind over the deck to take off without the catapult, over twice the distance the McDonnell FD-1 required. To put that into perspective, the length of the FDR's flight deck was just shy of 961 feet! It was also found that the J33 engine of the P-80 took as long as 2 minutes to spool up to full power after starting, which would greatly lengthen the deck launching cycle. From catapult takeoff, one circuit in the carrier landing pattern, and then an arrested landing, the P-80 used 37 gallons of fuel. By comparison, the Vought F4U Corsair only used 6 gallons. 

The next phase of carrier testing then involved flying the P-80 at operational loads which also included use of the tip tanks that were a fixture on USAF aircraft during the Korean War. It was quickly found that in this more realistic configuration the catapults of the day even with a strong wind over the deck were unable to launch the P-80. In addition, the wing structure where the tanks were attached was too weak and a stronger catapult would have just launched the P-80, leaving its tip tanks behind!

Before the carrier tests were performed, some in the Navy unhappy with BuAer's decision to go with McDonnell wanted to purchase the Lockheed P-80 Shooting Star instead. Lockheed even did some design work on what they called a P-80B for the Navy which would have had the Navy designation FO-1 (Lockheed's designator become V in the 1950s, so it would have been then known as FV-1). The deck trials quickly ended this proposal and McDonnell would go on to develop a whole line of fighters for the Navy from FD-1 Phantom, the F2H Banshee, the F3H Demon, the superlative F-4 Phantom II and today's F/A-18 Hornet. The Navy, did however, buy 50 P-80s to be used as shore-based trainers to allow naval aviators to gain jet experience. VF-6A (later renumbered VF-52) at NAS North Island and Marine squadron VMF-311 at MCAS El Toro operated the P-80s. Lockheed did, however, develop the TV-2 SeaStar based on the Lockheed T-33 in the 1950s. The T-33 required an extensive amount of modification to be suitable for carrier operation. In 1962 the TV-2 was redesignated the T-1 and was ultimately replaced by the North American T-2 Buckeye.

Source: U.S. Naval Air Superiority- Developement of Shipborne Jet Fighters 1943-1962 by Tommy H. Thompson. Specialty Press, 2008, p23-33.