Lindberg 1/48 X-3 Stiletto

If ever there was an aircraft that looked its moniker, it was the X-3 "Stiletto". Under direction of the US Air Force's Air Research and Development Command, and sponsored jointly by the US Navy, USAF and NACA, Douglas designed and developed a high-speed research aircraft under the designation Douglas X-3, later named Stiletto after its lines. Intended primarily for research into the problems of high-altitude, high-speed flight and the effects of kinetic heating, the X-3 began its design life in 1946. The complexity of this program is indicated by the fact that more than three years elapsed before approval was given for construction of a mockup, in August 1948, and it was not until late June 1949 that Douglas received a contract for two flying prototypes and one static test airframe; however, only one prototype was built (49-2892).

The X-3 had the most highly refined supersonic airframe of its day as well as other important advances including one of the first machined structures. It included the first use of titanium in major airframe components. Its long fuselage gave the Stiletto a high-fineness ratio and a low-aspect ratio (the ratio of the wing's span to its chord; in other words, it was short and stubby). Despite this refined configuration, the maximum speed it attained was Mach 1.21, which occurred during a dive. The general consensus was that the aircraft was sluggish and extremely underpowered by its Westinghouse J-34 power plants. The X-3 also demonstrated coupling instability during abrupt rolling maneuvers, which could cause it to go wildly out of control, as happened on a flight on Oct. 27, 1954, with National Advisory Committee for Aeronautics (NACA) pilot Joe Walker at the controls. The principle contribution of the X-3 was its data on inertial coupling (roll divergence) - a tendency to diverge from the intended flight path. The aircraft also shed its small tires routinely, leading to a revision of the design criteria for tires used on high-speed aircraft. This aircraft flew 20 times between 1954 and 1956 at the NACA High-Speed Flight Station (predecessor of NASA's Dryden Flight Research Center, Edwards, California). Joe Walker was the pilot for all 20 of these missions.

First flown on 20 October 1952 with Douglas test pilot Bill Bridgeman in the cockpit, the X-3 had a slender needle-nosed fuselage, a low-set cantilever monoplane wing of very short span, conventional tail unit, retractable tricycle landing gear and power provided by two Westinghouse J-34-WE-17 turbojets mounted side-by-side in the fuselage. The pilot was accommodated in a pressurized cabin, on a downward ejection seat that served also as an electric lift to provide access from the ground. Design of the X-3 was of unprecedented complexity because of the high-speed requirement, involving advanced aerodynamics and the use of new constructional methods and materials. They included, in particular, the development of fabrication and construction techniques involving the use of titanium. Additionally, the airframe had more than 850 pinhole orifices distributed over its surface to record pressures, 185 strain gauges to record air loads and stresses, and 150 temperature recording points. Testing proved disappointing, the aircraft being underpowered and able to achieve only 50 per cent of its design speed of Mach 2.2. With virtually no hope of improving performance, the USAF cancelled the program after only six flights and the aircraft was handed over to NACA.

However, the X-3 was not regarded as a failure, for it made important contributions to titanium technology, and features of its design were used later in Lockheed's F-104Starfighter and the SR-71 Blackbird. The X-3 was transferred to the U.S. Air Force Museum in 1956, where it resides today.

• Specifications:
• Type: high-altitude high-speed research aircraft
• Power plant: two Westinghouse J-34-WE-17 turbojets, each developing 4,200 lb (18.68 kN) thrust with afterburners
• Performance: maximum speed 706 mph (1136 km/h) at 20,000 ft (6095 m); absolute ceiling 38,000 ft (11580 m);
• Endurance: 1 hour
• Weights: empty 14,345 lb (6507 kg); maximum take-off 22,400 lb (10160 kg)
• Dimensions: span 21 ft 8 in (6.91 m); length 66 ft 9 in (20.35 m); height 12 ft 6 in (3.81 m); wing area 166.5 sq ft (15.47 m2)

  CONSTRUCTION

Interior:

The kit includes a two-piece seat with a pilot figure. I scratch built an instrument panel and shroud from sheet styrene. Cockpits parts were painted dark gull gray with the shroud painted flat black. The instrument gauges were done with Waldron punched disks of white trim film and reheat Models instrument gauge decals. The control wheel was scratch built using styrene rod, sheet, and a Waldron punched disk.

The figure was painted olive green with a different shade of olive used for the masking tape harnesses. The figure was hand painted after first airbrushing a gray primer.

Sidewall and side controls were scratch built with bits and pieces of styrene sheet, Waldron punched disks, and fine wire. Sidewalls were also painted dark gull gray with a couple of boxes painted semi-gloss black, A few Reheat Models control and data placards decals were utilized on both walls.

Engines and exhausts:

The kit contains a rather nice two-piece J-34 engine pair, but the exhausts were non-existent. I easily scratch built the exhaust and exhaust housing from two sizes of styrene tubing. The ends of both were cleaned out but using a motor lathe. The housings were painted steel and the exhausts burnt iron. The engines were painted gloss black, masked and the front painted bright aluminum with the rear done in graphite.

Exterior:

With exception of the extensive filling and sanding to cover holes for the electric engine included in this kit and the closed landing gear and engine access doors, this kit was as simple and easy as it gets. The kit has the usual overdone raised detail of its day, but this was easily sanded away in an evening at the workbench. The real task was getting all that filling sanded and contoured and rescribing the controls, engine access, ejection/entry port, and gear doors. The kit's overall fit was very good with little or no filler. I did not like the one-piece glazings for each side and cut them in two. I also sanded the interior surfaces much thinner from the thick plastic slab given. All were polished and given a coat of FUTURE. The only thing I replaced on the exterior was the nose pitot, which I replaced with hypo tubing and fine wire.