Following an announcement recently of the War Department there began the first flying tests at Wright Field, of a new departure in a specially-designed Beechcraft photographic plane. This is the first such plane which will carry the tandem camera installation of two T-3A cameras taking a tandem mounting. The first of two fleets of Model 18S twin-engine Beechcrafts designated by the Army Air Corps as Type F-2, in their conversion for photography purposes has been delivered. These planes are produced by the Beechcraft Aircraft Corporation, Wichita, KS, to which a contract totaling $528,749.00 had been awarded.
Powered by two Pratt & Whitney 9-cylinder radial engines, rated at 350 hp, using a two-bladed propeller of a little more than 8' in diameter, this all-metal, low-wing monoplane has a wing span of 47½' and carries no armament. Its gross weight is approximately 7000 pounds and holds a crew of pilot, navigator and photographer. Its ceiling may be placed at above 25,000 feet.
Equipped to carry cameras for photographing and mapping missions it carries, tor tactical mapping, the Fairchild T-3A tandem camera and probably the Fairchild K3B for oblique shots from the sides of the fuselage or pictures taken through the roof. For certain reconnaissance missions these may be replaced by the 24" focal length K7C for the tandem installation. Thus, whether it be for rapid reconnaissance mapping, tactical mapping or for high altitude mosaic and spotting purposes the F-2 plane is adapted to the employment of any indicated type of camera.
In its original try-out at Beech Field the Beechcraft, after thorough tests in all characteristics of structure and performance, was accepted by Air corps representatives and piloted from there to Wright Field, some 735 miles, by Capt Russell Kiellor in 3 hours and 38 minutes despite crosswinds of 40-70 mph velocity.
The design of the F-2 is such that maximum visibility is assured to both pilot and photographer and an advantage is secured in the facility with which takeoff and landing can be accomplished on the relatively small airports frequently used in the mapping of mountainous areas of the United States. Incidentally, a strap attached right and left of the "darkroom" door enables the photographer to secure himself in takeoffs and landings.
The immense employment of aviation in the current war in Europe conclusively proves the imperative need of accurate understanding of the enemy's terrain and the disposition of man-made works and troop or artillery dispositions, and the success of the bombing mission is in direct proportion to the excellence of the preliminary photographic mission. With the F-2 the United States Army is provided with a rapid, easily-maneuvered, well-equipped means of observation. Radio equipment including a commercial set completes the necessarily important liaison between ground and plane. An interphone system utilizing the throat microphone principle, is installed. In the drawing the photographer is shown with his left hand grasping the device holding the microphone button which is held down in the act of talking. A bracket on the wall to the man's right holds this instrument when not in use. To the navigator's right is a hand-controlled transmitter. Ordinarily talking between photographer and navigator occurs only between the taking of the pictures.
Between the photographer's knees is his view finder, rotatable in azimuth, which, with its ample-sized field, grid and bubble, enable him to maintain a constant check on "crab" and overlap. From the box on which he sits the source of the "electrical surge" comes the power which actuates the ten magnets which trip the shutters of the ten individual cameras.
Outstanding, in equipment, is the navigator's gyro-stabilized drift meter, substantially mounted and easily adjusted by a cylindrical bar to the operator's right. Immediately behind, on the floor, is a six-inch aperiodic compass.
To the right and left of the photographer and above in the roof are detachable sections into which a species of rubber-covered yoke can be affixed. Against this the single-lens camera may be thrust and firmly held while oblique pictures are taken. The roof opening permits the photography of subjects such as flight formations, overhead, where a clear vista is demanded. In the "darkroom" this single-lens camera may conveniently be stored or films changed.
High altitude flying is promoted with oxygen drums, two to a man, and the discomfort from cold reduced by heat intakes from the motor exhausts in the right and left walls and ceiling of the fuselage. Chest parachutes for each man are in convenient brackets.
Chief attention is directed to the tandem T3-A camera installation in the floor of the cabin and for which the door, with its movable, X-form arm guards is shown in the sketch . Operating at an altitude of 20,000 feet these double 5-lens combinations one component of which is turned at an angle of 45-° to the other are able to photograph an area of approximately 24,600 square miles with a 60% overlap in the direction of flight and about 30% side lap between adjacent strips. Sketches to the upper left of the drawing convey the theory of the employment of the two units as expressed with contact prints of the simultaneous exposures. However, in actual practice a secondary process is introduced. With reference to the plane of the ground only the central lenses of both units are parallel, the wing lenses being oblique. The final print, therefore, consists of a contact print from one of the central cameras and the wing prints are obtained by "transformer" which projects the images of the wing cameras in such manner that the correct perspective of the ground, with relation to that of the center camera, is achieved and in the ensuing combination of prints a true octagon is obtained without objectionable distortion of any of its parts. Differences in parallax at high altitudes are negligible.
The weight of the T3-A assembly with a full loading of film and camera accessories is about 360 pounds. Screws right and left of the cameras permit fore-and-aft leveling and the plane, itself, controls the lateral tilt. Vacuum is used to maintain flatness in the films and these are wound by the manually-operated handles seen projecting from the top sides of the central units.
This article was originally published in the August, 1940, issue of Aviation magazine, vol 39, no 8 pp 64-65, 146.
The original article has 1 photo and two drawings.
Photo is not credited.
[ F-2 on hardstand, seen from 11 0'clock] [ photo ]
Taking picture with single-lens camera through roof aperture [ drawing ]
[cutaway of F-2, seen from 11 o'clock high] [ drawing ]