By Tommy H. Thomason

Friday, October 31, 2008

General Purpose F8U

Most of the Navy's jet fighters through the 1950s to a greater or lesser degree were general purpose, in that they could also drop bombs and fire rockets. The F8U was an exception for a few years. It was originally equipped with an integral rocket pack, but this may have been primarily intended as an air-to-air weapon. In any event, it was deleted after the F8U-2 (F-8C).

The F8U-2NE (F-8E) was to have a full air-to-ground mission capability including the ability to fire Bullpup A and B, as shown in this iconic display, as well as Shrike and Walleye. These and conventional bombs up to 2,000 lbs were to be carried on a stores pylon added on each wing. A hump was added over the wing to house the Bullpup avionics.

In September 1963, OpNav deleted the requirement for Bullpup, Shrike, and Walleye qualification from the F-8E "because of cost and mission reassignment," but retained the Zuni and 2,000-lb bomb delivery capability. It does not appear that the Bullpup qualification was ever reinstated. The hump was eventually used for defensive ECM avionics.

For more on F8U Crusader armament changes, see

Monday, October 20, 2008

1950s Navy Day Fighter Specification

In the early 1950s, BuAer was not of one mind with respect to the specification for a carrier-based day fighter. The class desk officer (equivalent to a program manager), an experienced fighter pilot, thought the best airplane for the mission was simple, light, and maneuverable. Supersonic speed, and therefore an afterburner, was not only unnecessary, but undesirable. He placed a contract with North American for the FJ-4, a substantial modification of the FJ-3 Fury, which was in turn a variation of the Air Force's F-86 Sabre Jet. This would provide the earliest availability of his vision of the optimum day fighter. At roughly the same time, a competition was initiated for a new day fighter, with supersonic speed explicitly not required, among other stipulations to reduce unit cost and complexity. As luck would have it, his tour of duty at BuAer ended shortly after the request for proposal was issued and he left for his next assignment. The RFP was immediately amended in accordance with different views on what was needed in the new fighter. The result was the 1,000 mph F8U Crusader. Both are shown here on Forrestal in 1956 during carrier qualifications. All the FJ-4s produced were assigned to the Marine Corps. A subsequent derivative, the FJ-4B, was procured as an attack airplane to provide a backup to the A4D Skyhawk.

Friday, October 10, 2008

400 MPH! (?)

"On 1 October 1940, the XF4U-1 made a flight from Stratford to Hartford with an average ground speed of 405 mph, the first U.S. fighter to fly faster than 400 mph."

If that was the actual wording of the Vought press release, that's not too misleading. It doesn't claim a world record (it wasn't). It implies that the course was not flown in both directions, a record requirement that would eliminate a beneficial tail wind component*. Moreover, it specifically states that it was a ground speed, not an air speed, which is what really counts in an apples-to-apples comparison of airplane performance. It doesn't describe how, much less how accurately, the beginning and end points of the speed run were determined from an altitude of over 20,000 feet. (At the time, speed records had to be set at a very low altitude. However, top speed for propeller-driven airplanes was attained at altitude. Click Here for examples.) It also doesn't state the engine rating or horsepower used. The distance, about 50 miles, does limit the amount of altitude that could be exchanged for speed and reduces the impact of an error in determining the beginning and end points.

The Navy's Service Acceptance Trials report provides a more accurate measurement of the XF4U's performance: 371 mph at rated power with the specified useful load. (Click the picture for a readable version.) The Navy did wind it up to 402 mph, but with the "radio mast and antenna not installed, the gun holes and handholds faired." There's no mention of what rpm and manifold pressure were used to attain that speed.

To be fair, the XF4U was powered by the X model of the Pratt & Whitney R-2800 engine. Later production models of the Corsair with more developed and powerful R-2800 engines were capable of exceeding 400 mph in level flight at altitudes above 20,000 feet.

Ron Lewis also notes that the Lockheed P-38 Lightning was the first fighter to exceed 400 mph in level flight, making the XF4U the first single-engine fighter to do so. In a quick interweb search, I didn't find a Lockheed or Army Air Forces claim that the sole XP-38—which first flew on 27 January 1939 and crashed about two weeks later at the end of an attempt to set a transcontinental speed record—reached 400 mph in its brief flight test career. It was reportedly capable of that (click HERE). The first YP-38 flew on 17 September 1940, about two weeks before the XF4U's "400 mph" flight, a second chance for the Lightning to have beaten the XF4U to that milestone. Again, I didn't find a report of a claim to that effect. Therefore, although the P-38 was appears to be the first U.S. fighter capable of 400 mph in level flight, Vought might have been correct with respect to the XF4U being the first to actually do it.

* At the same altitude both ways. There was a helicopter speed record set by taking advantage of a tail wind in both directions, but that's a story for another time...

Wednesday, October 1, 2008

Davis Barrier Redux

Blogdog asked about the difference between the Davis barrier and the barricade because he was aware that both involved straps. A detailed explanation is provided in my book, U.S.Naval Air Superiority, but the brief answer is that the Davis barrier was a modification of the existing barrier specifically to stop jet and twin-engine airplanes; the barricade was a subsequent addition to handle situations where the Davis barriers weren't effective. The upper photo is a fit check of an AJ-2 Savage and the barricade. The lower photo is of a fit check of an early version of the Davis barrier. The top strap is the "actuator" and is located where the steel cable was for stopping single-engine propeller-driven airplanes that didn't hook a wire. The steel cable is now lying on the deck. If the jet or twin-engine airplane arrived at the Davis barrier untrapped, the nose gear would snag the top strap. The vertical straps would then pull the cable up as the airplane continued forward, hopefully in time to engage the main landing gear struts and drag the airplane to a stop. A barrier actuator (a simple post, often extended by a spring when the tailhook was lowered) was provided in front of the windscreen to activate the barrier if the nose gear had collapsed.

There was a shortcoming. If the airplane was going too slowly when it hit the Davis barrier, the cable would fall back down before it caught the main landing gear. If the airplane was going too fast, the cable would not get up high enough, fast enough, and the airplane would roll right over it, unstopped. As it turned out, the combination of the Davis barrier and the barricade also proved to be what was needed to safely operate jet airplanes on axial decks, in terms of almost always keeping a crash from involving the people and planes forward of the barricade.

For other posts I've made on the Davis barrier and the barricade, see: