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From: "Bob (not my real pseudonym)" <invalid@invalid.invalid>
Newsgroups: alt.binaries.pictures.aviation
Subject: Re: Northrop X-4 Bantam
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I read about this newfangled invention called a "thermos"...
On 23 Oct 2018 07:10:25 -0700, Miloch <Miloch_member@newsguy.com>
wrote:
>https://en.wikipedia.org/wiki/Northrop_X-4_Bantam
>
>The Northrop X-4 Bantam was a prototype small twinjet aircraft manufactured by
>Northrop Corporation in 1948. It had no horizontal tail surfaces, depending
>instead on combined elevator and aileron control surfaces (called elevons) for
>control in pitch and roll attitudes, almost exactly in the manner of the
>similar-format, rocket-powered Messerschmitt Me 163 of Nazi Germany's Luftwaffe.
>Some aerodynamicists had proposed that eliminating the horizontal tail would
>also do away with stability problems at fast speeds (called shock stall)
>resulting from the interaction of supersonic shock waves from the wings and the
>horizontal stabilizers. The idea had merit, but the flight control systems of
>that time prevented the X-4 from any success.
>
>Two X-4s were built by the Northrop Corporation, but the first was found to be
>mechanically unsound and after ten flights it was grounded and used to provide
>parts for the second. While being tested from 1950 to 1953 at the NACA
>High-Speed Flight Research Station (now Edwards Air Force Base), the X-4's
>semi-tailless configuration exhibited inherent longitudinal stability problems
>(porpoising) as it approached the speed of sound. It was concluded that (with
>the control technology available at the time) tailless craft were not suited for
>transonic flight.
>
>It was believed in the 1940s that a design without horizontal stabilizers would
>avoid the interaction of shock waves between the wing and stabilizers. These
>were believed to be the source of the stability problems at transonic speeds up
>to Mach 0.9. Two aircraft had already been built using a semi-tailless
>British de Havilland DH.108 Swallow built after the war. The United States Army
>Air Forces signed a contract with the Northrop Aircraft Company on 11 June 1946,
>to build two X-4s. Northrop was selected because of its experience with flying
>wing designs, such as the N-9M, XB-35 and YB-49 aircraft.
>
>The resulting aircraft was very compact, only large enough to hold two
>Westinghouse J30 jet engines, a pilot, instrumentation, and a 45-minute fuel
>supply. Nearly all maintenance work on the aircraft could be done without using
>a ladder or footstool. A person standing on the ground could easily look into
>the cockpit. The aircraft also had split flaps, which doubled as speed brakes.
>
>
>Role
>Tailless aircraft prototype
>
>Manufacturer
>Northrop
>
>First flight
>15 December 1948
>
>Status
>Preserved
>
>Number built
>Two
>
>The first X-4 (serial number 46-676) was delivered to Muroc Air Force Base,
>California, in November 1948. It underwent taxi tests and made its first flight
>on December 15, 1948, with Northrop test pilot Charles Tucker at the controls.
>Winter rains flooded Rogers Dry Lake soon after, preventing additional X-4
>flights until April 1949. The first X-4 proved mechanically unreliable, and made
>only ten flights. Walt Williams, the head of the NACA Muroc Flight Test Unit
>(now Dryden Flight Research Center) called the aircraft a "lemon". The second
>X-4 (serial number 46-677) was delivered during the halt of flights, and soon
>proved far more reliable. It made a total of 20 contractor flights. Despite
>this, the contractor flight program dragged on until February 1950, before both
>aircraft were turned over to the Air Force and the NACA. The first X-4 never
>flew again, used as spare parts for the second aircraft.
>
>The NACA instrumented the second X-4 to conduct a short series of flights with
>Air Force pilots. These included Chuck Yeager, Frank Kendall Everest, Jr., Al
>Boyd, Richard Johnson, Fred Ascani, Arthur Murray and Jack Ridley. The flights
>were made in August and September 1950. The first flight by an NACA pilot was
>made by John H. Griffith on September 28, 1950.
>
>The initial NACA X-4 flights, which continued from late 1950 through May of
>1951, focused on the aircraft's sensitivity to pitch. NACA pilots Griffith and
>Scott Crossfield noted that as the X-4's speed approached Mach 0.88, it began a
>pitch oscillation of increasing severity, which was likened to driving on a
>washboard road. Increasing speeds also caused a tucking phenomenon, in which the
>nose pitched down, a phenomenon also experienced by the Me 163A Anton prototypes
>in 1941. More seriously, the aircraft also showed a tendency to "hunt" about all
>three axes. This combined yaw, pitch and roll, which grew more severe as the
>speed increased, was a precursor to the inertial coupling which would become a
>major challenge in the years to come.
>
>The X-4's primary importance involved proving a negative, in that a swept-wing
>semi-tailless design was not suitable for speeds near Mach 1, although the F7U
>first aircraft to demonstrate stores separation above Mach 1. Aircraft designers
>were thus able to avoid this dead end. It was not until the development of
>computer fly-by-wire systems that such designs could be practical. Semi-tailless
>designs appeared on the X-36, Have Blue, F-117, and Bird of Prey, although these
>aircraft all differed significantly in shape from the X-4. The trend during its
>test program was already towards delta and modified delta aircraft such as the
>Douglas F4D, the Convair F-102A derived from the XF-92A, and the Avro Vulcan.
>
>Specifications (X-4)
>
>General characteristics
>Crew: one
>Length: 22 ft 3 in (7.09 m)
>Wingspan: 26 ft 10 in (8.18 m)
>Height: 14 ft 10 in (4.52 m)
>Wing area: 200 sq ft (18.6 m2)
>Aspect ratio: 3.6:1
>Empty weight: 5,507 lb (2,500 kg)
>Max. takeoff weight: 7,820 lb (3,550 kg)
>
>Performance
>Maximum speed: 625 mph (543 knots, 1,006 km/h)
>Range: 420 mi (365 nmi, 676 km)
>Service ceiling: 42,300 ft (12,900 m)
>Rate of climb: 7,700 ft/min (39.1 m/s)
>
>
>
>
>*
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