In February 1980, General Dynamics proposed use version Fighting Falcon with the structurally modified form of the wing, initially proposed for use on the Concorde supersonic aircraft type. The project has received the title of SCAMP (Supersonic Cruise and Maneuvering Program), and then was renamed F-16XL. Deltoid delta wing with double swept across the front edge possessed a total area of 58.8 square meters (more than twice the area of standard-wing F-16).
Research objectives were innovative forms and the curvature of the wing profile to provide efficient supersonic cruise speed, while maintaining the flexibility to all this sound fighter. The design was to provide a low resistance at high subsonic or supersonic speeds without harm maneuverability at low speeds.
The program initially was funded by the manufacturer, and it was involved two experienced F-16A. In the late 1980s the U.S. Air Force and General Dynamics have agreed on a joint test program there, and the Air Force provided the third and fifth experienced F-16 (tail number A-3, serial number 75-0747 and A-5, serial number 75 -0749) to be converted into layouts F-16XL.
The fuselage was lengthened by 142 cm to 16.5 meters means 2-new insertions on the connections between the 3 main nodes of the fuselage, one 66-centimeter and the insert was located at the rear of the wing coupling (rear split point), and 76-cm long and in front. But back 66-centimeter and insert does not represent a continuous section from the bottom to the top. Below the wing, a 26 inch segment was inserted just aft of the main landing gear, above the wing the segment was still 26 inches long, but inserted 26 inches farther aft than the segment below the wing. Under the wing of this insert, 26-inch sector introduced specifically aft of the main chassis, above the wing sector as before 26 inches long, 26 inches but inserted further aft than the sector under the wing. As a result, this insertion was similar to the reverse «Z». Lengthening the fuselage tail section have allowed to make a beveled 3 degrees, the right to prevent the motor nozzle touch the runway during takeoff and landing.
For the same reason XL has no ventral fins, but it it not necessary because in general the properties XL stability was higher than the F-16.
Sixty-six centimeter inset influenced intake motor own lower part, so as the front fuselage insert was used only for the upper part of the fuselage. As a result, engine air intake F-16XL was at 66 cm longer than the standard F-16A.
Wing shape in the plan was changed to the swept wing with a break on the front edge of the area by 120% more than the original wing of the F-16. In order to maintain the weight of the new wing in his upper and lower layers of the skin are widely used carbon composites. So Makar, weight savings in the wings was only 272 pounds. Design wing spar has a sweep angle of 50? up to 70? and began at 1179 kilograms heavier than the ordinary. Increase the internal volume as by lengthening the fuselage and wing extensions increment of 82% internal fuel tanks, and the increased wing area has allowed to increment the number of suspension points to 27 and increasing with all this combat load by almost 2 times. Despite the resulting lengthening of the fuselage, the new XL designation denotes not «Extra Large» (Very large).
Means of improving and optimizing the shape of the wing profile curvature, the final configuration of the aircraft provided 25% improvement in maximum lift relative to the F-16 at supersonic speeds and 11% improvement at subsonic. Maneuverability F-16XL quite different from the standard F-16, providing a more stable (smooth) flying at high speeds and low altitudes. Eventually came very ably fighter?? With a huge wing ensuring integration of a huge number of weapons on the outside hangers.
1st of 2-F-16XL (serial number 75-0749) underwent a change was a single turbojet engine and equipped with F100-PW-200. The first time he picked up in the sky on July 3, 1982, James McKinney (James McKinney). Second F-16XL (serial number 75-0747) originally equipped with a turbojet engine General Electric F110-GE-100 with a thrust of 13 tons. It was modified from the third prototype aircraft (tail number A-3), which was severely damaged in tragedy when landing during a day or open doors in August 1980. During takeoff the aircraft nose landing gear tire burst. The decision was made to sit down without letting the chassis. As a result, the plane is damaged. When the glider arrived in Fort Worth for use in the program XL lacked a whole front part of the aircraft. During repairs, it has been converted to a double. As aircraft XL it was first flown on October 29th, 1982, piloted by Alex Wolff (Alex Wolf) and Jim McKinney (Jim McKinney).
In March 1981, the U.S. Air Force announced the development of new and improved tactical fighter. General Dynamics offered for competition fighter F-16XL, and the company McDonnell Douglas Double F-15B Eagle. With increased fuel capacity and payload F-16XL could carry twice as many weapons than the F-16 and had a 40% increase in flight range. Increased combat load can be located on the 27th and followed hardpoints located as follows:
16 under the wings to 340 kg every
4 suspension missiles AMRAAM AIM-120, partly sheltered in the wing root
2 on the wingtips
1 ventral central pylon
2 under the wings for «languid» ammunition
2 in the lower front part of the fuselage for low-altitude navigation systems LANTIRN infrared sighting
Yet, «languid» suspension was placed on each wing at the same distance from the center of the fuselage, and that two ordinary suspension. This means that you can use or a «languid» or two ordinary suspension, but not both at once.
In addition, when «heaviest» suspension was placed additional fuel tank, on a physical level it closed another point suspension under the wing. Because with external fuel tanks, the largest number of points for the suspension arms on the wings was reduced to 10. On the other hand, the attachment device 2-bombs could also be located under the fuselage. Without the use of additional fuel tanks greatest number of rounds of ammunition 227 kg was increased to 16. XL also could carry under the fuselage, resettable 1100 liter fuel tank.
In February 1984, the U.S. Air Force announced preference fighter known as McDonnell Douglas F-15E Strike Eagle. If F-16XL won a contest that could be produced aircraft F-16E as a single and F-16F as doubles. Lead Project Engineer XL John G. Williams (John G. Williams) said: «XL raschudesny plane, but he was a victim of the U.S. Air Force wanting to continue building F-15, which is completely understandable. From time to time you win these political games from time to time not. By most superior characteristics XL F-15 as an assault aircraft, and the F-15 is pretty good. «
After losing in the Ministry of Defence in the summer of 1985 returned both General Dynamics F-16XL in Fort Worth, where he placed them in storage. These aircraft made 437 sorties and 361, respectively, and although supersonic cruising speed without afterburner was the initial goal of applets F-16XL, plane never managed to fulfill it completely.
At the end of 1988, both experienced reference have been removed from storage transferred NASA, where they were assigned hull numbers 849 (A-5, # 75-0749) and 848 (A-3, # 75-0747). At NASA, they were used to study the concept of aerodynamics of the wing to improve airflow at supersonic flight.
First F-16XL again took to the air on March 9, 1989 and the year flew in Flight Research Center Ames-Dryden at Edwards AFB. This aircraft has been modified to study the impact of the motion of vortex flows along the wing. For this purpose, the experimental part of the left wing of titanium (referred to as gloves) were done by laser millions of tiny holes (about 2500 holes per square inch, half square meter of total holes).
The purpose of this device is designed and built by Rockwell International’s North American Aircraft Division was to delay (by active suction) boundary layer of air, ensuring its laminar flow. This turbulent air layer formed on the surface of the wing typically adversely affect the flying characteristics, causing excessive drag and fuel consumption. Removing the turbulent layer of air laminar flow wing touches the surface creating all this even less resistance. NASA research to improve laminar flow began in 1926, the year when the predecessor organization of NASA, National Advisory Committee for Aeronautics (NACA) photographed airflow turbulence in the wind tunnel to own the Langley Research Center in Hampton, Virginia. In the air flow was introduced smoke and photographed showing visual signs of turbulence on the upper surface of the wing.
Of early studies led to the advice about how to resolve the sources of turbulence and eliminate the appearance of protruding rivet heads and other features contributing to the emergence of turbulence at high flight speeds.
First flight with a new wing was held on May 3rd, 1990, the aircraft ran pilot Steve Ishmael (Steve Ishmael). In January 1995, he held a series of high-speed tests with the aircraft NASA SR-71. Aircraft were used to investigate the characteristics of the sonic boom under applets creation supersonic passenger aircraft. Speed during these test flights ranged from 1.25 to Mach 1.8 Mach. During flight engineers as recorded on sonic booms affect atmospheric conditions.
Later, Air Force One was transferred to NASA Langley, Virginia, where he entered the program from flight tests in order to improve flight characteristics during takeoff and reduce motor noise. It was painted in a dark color with yellow stripes and snow-white front part of the fuselage. Room 849 aircraft returned to Edwards Air Force Base in 1995, the year where he took part in the study of sonic booms along with SR-71A.
Second F-16XL (two-seater) was delivered to NASA’s experimental engine, which had to change before the start of flight testing. NASA received engine General Electric F110-129 ensured surprisingly excellent properties. Supersonic cruising speed of Mach 1.1 in the case was already achieved first applets at an altitude of 6000 meters. Passive «gloves» (Fairing foam and fiberglass) were installed on the right wing in order to study aerodynamic characteristics along the front edge at supersonic speed, noise and pressure. On the left wing was set a new active fairing?? (Twice the size installed on the last plane) made of plastic foam and fiberglass fairing around the test section of sverhtehnologichny composite porous shell of titanium. Despite the disproportionate wings plane okazlsya easy to operate.
The fairing has a highest thickness of 63 mm, and covers 75% of the surface of the wing and 60% of its front edge. S-shaped contour of the wing was extended on the left side is straight forward to more closely match the proposed form svrhzvukovogo wing passenger aircraft. Active site (average 66% of the fairing) has at least 2,500 the done last laser holes and covers at least the last area of 0.9 square meters. The openings 20 lead into the cavity beneath the surface of the wing to control suction applied at the surface of the wing. Fairing is glued to the casing itself by means of epoxy resins. Once the plane was removed paint on composite cladding were applied couple layers of fiberglass, acting as skin protection when removing the fairing. Currently, the aircraft is used as a test panel in a research project of supersonic laminar flow.
Aircraft performance properties:
Crew: one (two in the second XL)
Length of the aircraft with a barbell LDPE: 16.51 m
Wingspan: 10.44 m
Height: 5.36 m
Wing Area: 61.59 m?
Empty weight: 9980 kg
The biggest take-off weight: 21,800 kg
Engine type: turbofan Pratt & Whitney F100-PW-200, General Electric F110-GE-129 (the second plane)
Thrust: 54.5 kN 76.3 kN (second plane)
Most thrust: 106.0 kN, 128.9 kN (second plane)
The highest speed at altitude 12000m: Maha/2027 1.8 km / h, 2.05 Maha/2253 km / h (second plane)
Cruising speed: 965 km / h
Practical range: 4590 km
Service ceiling: 15,240 m
Rate of climb: 315 m / s
Most operating load: 9
Armament: shestistvolnaya20 mm cannon General Electric M61A1 Vulcan (6000 rounds per minute, 511 rounds)
Combat load: — 6800 kg-17 hardpoints
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