Experimental aircraft «Douglas X-3 Stiletto»

Experimental aircraft «Douglas X-3 Stiletto»
The aircraft was designed for flight research features trapezoidal wing of small aspect ratio and aerodynamics fly at speeds of 2460-3690 km / h Military department of the United States associated with this plane enormous expectations — study had very assist in increasing the power of defense. Because all project information in its time was one hundred per cent classified.

Experimental aircraft «Douglas X-3 Stiletto»

Agreement on the establishment of experimental aircraft was concluded with «Douglas» in 1947. Design, development and establishment of an aircraft lasted about 5 years. For now designers have studied more than 60 different variants of assembly and aerodynamic configurations using available at the time propulsion. Ultimately, experts at the company on the development of the aircraft braked by traditional way. As the power plant using the latest two turbojet engine J46 (up to 37.8 kN thrust) from «Westinghouse».

Experimental aircraft «Douglas X-3 Stiletto»

But the development of experimental aircraft proved that the real thrust engines «J46» was much less than the stated features. Had to increase the diameter of installed engines, resulting in the inability to use «J46», also be used with the least traction engines, which could hardly disperse Douglas X-3 «Stiletto» up to speed 1st Mach. At such speeds could only examine the wing airframe vibration. Building a prototype airplane finished by November 1951. But work on changing the design and modification of engines delayed the first flight of Douglas X-3 «Stiletto» almost a year. According to the contract, was ordered two copies of experimental aircraft, but due to problems with financing and propulsion was absolutely assembled one instance of «X-3 Stiletto», the second instance, and not completed, allowed for spare parts for the first reference . First plane fly into the sky made October 20, 1952, and the first supersonic flight took place in June 1953. Research and flights lasted until 1956, the highest speed reached by plane 1120 km / h Studies have shown that low-thrust, high specific load on the wing and high speed take-off and landing aircraft make very dangerous to use, especially when making take-off and landing.

Arrangement and design
Experimental «Douglas X-3″ — is a mid-built according to the traditional scheme with trapezoidal straight wing. The wings are made with the introduction of the profile of the diamond type relative width of up to 3 per cent and has a nasal flaps, ailerons and flaps with slotted outer hinge nodes, which are located in the elongated fairing. Because of the huge load on the wing (up to 1000 kg / m), it is made of titanium with a solid cross-section. Fuselage «X-3 Stiletto» got a huge extension (fuselage length exceeds the length of the wing is almost three times) that ends a sharp nose and smoothly goes into the low-profile tapered lantern. To ensure the greatest aerodynamic parameters of the fuselage, cockpit performed with the least comfort — test pilot had to sit in the cockpit with a small slope. Due to the shape of the fuselage, having a front-stretched island part company tail end, experimental aircraft called unofficially — flying pen. Pilot cockpit is inserted into the middle part of the fuselage, without breaking sheathe body geometry, and equipped with a windproof design has a triangular cross section. The design consists of 2 sheets of Plexiglas. Chair test pilot shifted to the left-back relative to the axis of symmetry. At ejection seat is shot down, has two automatic stabilizer and that automatic pilot separates from the ejection seat when it reaches the height of 3.4 thousand meters. If a bailout occurs below a given height, automatic pilot separates after 3 seconds after separating from the aircraft seat.

The plane made for research wing features at tremendous speeds, more than 3 Mach because cockpit equipped with air-conditioner evaporator water type and artificial cooling of the forward fuselage, what used forced circulation of aviation fuel under the body.
Empennage done in the usual way symmetric type rudder and stabilizer manageable. Manage tail occurs by irreversible hydraulic drive. Chassis — three legs ending with one wheel, completely retractable into the fuselage «Douglas X-3« Stiletto ».

In this plane — pilot flying laboratory, installed various equipment and apparatus, weighing 550 pounds. Properties pressure readings were made with 850-minute points on the entire surface of the aircraft, the properties were removed from the stress of 185 points, and the temperature data at 150 points. Installed low-power engines «J34-WE-17″ with 15.3 kN thrust up, filled afterburners, placed in the central part of the fuselage. Between them installed fuel tank. Vozduhopoglotiteli with flat oval section unregulated type, located on the edges of the fuselage, in its upper part, immediately behind the cockpit. Their slots are serving outlet boundary layer of the shell plating. Adjustable nozzle engines are made at the end of the central part of the fuselage under the clip feathers.

In 1956 he was one hundred percent finished tests «Douglas X-3 Stiletto». With him take off all hardware and equipment and give Dayton United States Air Force Museum in Ohio. Although unable to carry out all scheduled study of more meaningful contributions «Douglas X-3 Stiletto», in the development of aviation, aircraft landing gear suddenly becomes, specifically material tire wheel. After the aircraft had to sit down and soar at speeds of over 250 km / h «Douglas X-3 Stiletto» became one of the most complex construction of the X-Series aircraft, but visually came the prettiest of all experimental aircraft built in the United States.

Experimental aircraft «Douglas X-3 Stiletto»

The main properties:
— Length — 20.3 meters;
— wing — 6.9 meters;
— height — 3.8 m;
— Weight empty / takeoff — 6.5/10.1 tons;
— fuel — 3.7 thousand liters.;
— Joint rules / Furious — 15/22 kN;
— rise to 96.5 m / s;
— longest duration flight — 60 minutes;
— length takeoff / landing — 2/4 mile;
— altitude ceiling — 11.5 km;
— coefficient of thrust-weight ratio — 0.44;
— design speed — 2200 km / h;
— real speed — 1120 km / h;
— low speed (stall) — 324 km / h;
— crew — 1 test pilot.
— Merit: speed — at a height of 0.98M 6.1 kilometer, achieving 10.6 km altitude for 303 seconds.

Created by Roman Dzhereleyko

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