Designed for large-scale subcontracting and extensive use of wood and steel, the Armstrong Whitworth Albemarle twin-engine mid-wing reconnaissance-bomber is, after many production schedule delays, being delivered to the RAF.
While originally designed in 1939 as a medium bomber, the hold-up in production, coupled with tactical changes, have changed this model's status so that the Series II craft now being delivered are generally used for observation, glider tow, or transport duties.
Fuselage is designed for construction in three parts (front, center, and aft) the first two being attached, respectively, to front and rear wing spars. Framework of the front section is of stainless steel, with the other two utilizing high tensile steel. Covering, of unstressed plywood, attaches to spruce formers.
Armor plating is set ahead of the front spar as a folding door between the front and center fuselage sections. Flooring over the bomb bay located under the spars and extending fore and aft is of sheet alloy for additional armor.
In profile, the bombardier's compartment bears considerable resemblance to that of the American-built North American B-25 Mitchell. Normally, the Albemarle crew includes but one pilot (seated on the left side of the cabin above and behind the bombardier), but an extra control column is carried for use by a co-pilot, who would use a folding seat mounted in the right side of the cabin. Radio operator-navigator's compartment is immediately aft of the pilot's seat. A four-gun Boulton Paul power turret with a 360° arc is set atop the fuselage somewhat like the mounting in the Bristol Beaufort just aft of the wing trailing edge. The extreme aft end of the fuselage under the stabilizer and elevators is glassed in for observation work, with the glider tow attachment (when installed) set just below the transparent portion.
The wing is built in three main portions: Center section, extending through the fuselage to the engine mounts, and two outer panels. Center section main spar is built up of four square-section steel booms and attachment to the fuselage is through eight pins, four on each of the fore and aft faces, to the front and center fuselage sections. Aft of the rear spar are detachable sections built up of spruce and plywood ribs for most of the length and, to carry flap hinge loads, steel tube ribs. Hydraulically operated three-position flaps are built up of tubular steel spars, spruce and plywood ribs, and plywood covering.
Outer wing panels have two spars, built up of spruce booms reinforced by light alloy inserts and plywood webs. Plan bracing comes from steel tubes attached to the spars through steel channel gussets. Normal ribs are of conventional construction spruce booms and plywood webs. Ribs which carry aileron hinges are spruce and plywood, reinforced by steel channels between-spars, and square steel tubing with gusseted joints aft of the rear spar. Ailerons are of construction similar to that used for the flaps.
Stabilizer is of all wood construction, the two spars consisting of spruce booms and plywood web. It is attached to the fuselage by two bolts on the front spar and two adjustable links on the rear spar. Elevators are plywood covered, with the trim tab set in the port side and the balance tab on the starboard.
Twin fins and rudders are rounded off, somewhat like those of the Lockheed Hudson and Ventura, and like those on these planes, they are set-in approximately 18" from the tips. Both are similar in construction to the stabilizer, except that the rudders employ single tubular steel spars.
Power plant consists of two 1,560-hp Bristol Hercules XI two-row 14-cyl air-cooled radials, spinning three-bladed full-feathering de Havilland propellers of 14' 6" dia. Delivered as "power eggs," the engines are bolted to the wing at four points, the load being distributed through two tubular steel ribs at the outboard end of the wing center section.
Hydraulically operated landing gear is tricycle type, Lockheed-built. with both nose and main wheels retracting back the nose wheel up into the fuselage beneath the bombardier's compartment and the main wheels into the engine nacelles, where they are partially enclosed by light alloy metal fairing. Accompanying box tabulates data on craft.
|Specifications & Performance Data|
|Wing area||803.5 sq ft|
|Gross wt||22,600 lb|
|High speed||250 mph|
|Power||two 1,560-hp Bristol Hercules XI|
This article was originally printed in the April, 1944, issue of Aviation magazine, vol 43, no 4, pp 180-181.
The original article is illustrated with 3 photos and a 3-view silhouette.
One photo credited to British Combine; other photos and silhouettes not credited.