THIS IS THE FLYING FORTRESS, B-17F:
A 4-ENGINE, MID-WING MONOPLANE OF ALL-METAL, ALUMINUM ALLOY, STRESSED-SKIN CONSTRUCTION.
The fuselage is a series of aluminum alloy rings (circumferential stiffeners) fastened together by aluminum strips (longitudinal stiffeners), covered by an aluminum skin. The fuselage is constructed in four sections: (1) the plexiglas nose; (2) the forward section; (3) the rear section; and (4) the "stinger" tail section.
Tail surfaces, both vertical and horizontal, are similar in structure to the wings, except that sheet stiffeners, instead of corrugated sheet, are used to support the skin. The loads on these surfaces are lighter, hence the structure is made comparatively lighter.
Each wing consists of (1) an inboard panel; (2) an outboard panel; (3) a wing tip; (4) a flap; and (5) an aileron. A trim tab is provided in the left aileron only.
The engine nacelles, of semi-monocoque design, are installed in each inboard wing panel.
The wing construction: spars and highly stressed ribs of the truss type. Corrugated dural sheet, attached to the rib cords, reinforces the skin to withstand compression loads.
The B-17F has four 1200 Hp Wright Cyclone Model R-1820-97 engines of the 9-cylinder, radial, air-cooled type with a 16-to-9 gear ratio.
Each engine has a turbo-supercharger to boost manifold pressure for takeoff and maintain sea-level pressure at high altitude.
The Hamilton Standard 3-bladed propellers are hydromatically controlled with constant-speed and full feathering provisions. Adjustment of the propeller governors is accomplished individually by cable controls from the cockpit. Feathering and unfeathering is accomplished hydraulically by an electric motor-driven pump mounted on the forward side of the firewall in each engine nacelle.
MAIN LANDING GEAR
The B-17F landing gear is of the conventional type: left hand and right hand main gear and a tail gear.
The main gear retracts into the nacelles behind the inboard engines. Electrically operated retraction units, with auxiliary manual systems, are used for raising and lowering the main wheels. The emergency hand crank connections for operating the main landing gear are at the forward end of the bomb bay on each side of the doorway leading to the cockpit.
The tail gear consists of a wheel assembly, knuckle, treadle, oleo, retraction unit, anti-shimmy brake and wheel lock. Provisions are made for 360° rotation of the wheel, and for locking the wheel in a straight fore-and-aft position during takeoff. The tailwheel gear may be retracted either electrically or manually. Electrical retraction is controlled in the cockpit with the same toggle switch that controls the main landing gear retraction motor. For manual retraction, a hand crank is operated through the motor slip clutch.
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