FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1951
1951 - 0339.PDF
215 FLIGHT 23 February 1951 Features of the Scorpion apparent here are the slim fuselage, thin, low- aspect-ratio wings and large tip- tanks. The second prototype is shown. ALL-WEATHER FIGHTER / Features of the Northrop F-89A Scorpion, Designed for ~lt^~M rht and Bad-Weather Interception: Production for U.S.A.F.Mght RADAR aids have enabled the bomber of to-day toseek out and destroy its target in darkness or throughcloud. The defending fighter likewise uses radar to find its quarry under similar conditions. Such an intercepter, with its crew of pilot and radar observer, its airborne- interception equipment, and aids to navigation and landing, is of necessity a relatively large and complex aircraft. A typical example is the Northrop F-89A Scorpion, which has an all-up weight greater than that of a bombed-up Wellington. The Scorpion, which was one of the first jet-powered all-weather fighters built in America, is a descendant of the Northrop F-61 Black Widow, itself the only American night fighter designed as such during the last war. When the prototype Scorpion made its first flight on August 16th, 1948, the U.S.A.F. had already ordered in quantity its Curriss counterpart, the Blackhawk. Within two months, however, the Curtiss contract was cancelled, and Northrop's received an order for 48 Scorpions, later increased to 112. This total was further increased after the beginning of the Korean crisis, and F-89 production has since been speeded up. As an interim measure, the U.S.A.F. ordered a substantial number of Lockheed F-94 single-jet all-weather fighters; this design, being based on the T-33 two-seat Shooting Star, was amenable to quick production. The all-weather fighter is still a comparatively rare species; the Avro Canada CF-100 (which probably has a higher performance than the Scorpion) is the only aircraft of this type being produced within the British Common- wealth. This brief survey of the American aircraft, though limited by security restrictions, is therefore of particular interest on this side of the Atlantic. The Scorpion fuselage has a particularly high fineness- ratio. Its nose is occupied by the radar scanner, behind which are mounted the six 20-mm guns and their ammuni- tion. Pilot and observer sit in tandem ejector seats inside the pressurized cockpit, covered by a one-piece canopy. The rear fuselage sweeps up to hold the single fin and high-mounted tailplane clear of exhaust gases and wing- wake. In overall layout, the Scorpion is reminiscent of the Bell XP-59, America's first jet aircraft; the resemblance stems largely from the installation of the two power-units, which are slung beneath the mid-wing on either side of the fuselage. The turbojets are Allison J-35-A-21S, axial-flow units rated at 4,900 lb each (6,800 lb with afterburning). Internal fuel tanks are situated in the fuselage—imme- diately aft of the cockpit—and wings. Large tip-tanks are also provided and are, apparently, integral structures. The straight wings are reported by one American source to give "the same drag-alleviation or increase in critical Mach number as would a wing sweep of 35 deg." This low drag-coefficient at high speeds is said to be a function of low thickness-ratio (only 8J per cent at the root, 7J per cent at the tip) and low aspect-ratio. The deep root-chord of 15ft was, in any case, necessary to maintain the wing thinness while accommodating a structurally sufficient main spar. Full hydraulic power is provided for all the controls, which themselves form one of the most interesting design- features of the Scorpion. The Black Widow employed "retractable" spoiler-type ailerons and its jet successor is equally unorthodox in using split ailerons or "decelerons." In normal flight the upper and lower sections of the aileron are joined and function in the normal way; for use as dive brakes they part, and present equal areas above and below the wing. On the landing approach, the lower segments move downwards in conjunction with the double-slotted flaps, providing, in effect, a full-span flap. The undercarriage is of the nosewheel type, with main units retracting inwards into the wings. Narrow-section tyres, of nearly 200 lb pressure, are employed. The twin- wheel nose unit, placed behind the guns, retracts rearwards. For electrical services, a 120-volt system is provided and, The assembly line for Scorpions in Northrop's factory at Hawthorne, California. Before the outbreak of the Korean war, 112 Scorpions were on order for the U.S.A.F.; the contract has since been increased.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
