AI--Aircraft Interception Sets


SCR-540 Long Wave AI Set

SCR-540 in P-70
SCR-540 in P-70

The SCR-540 is a long wave AI equipment designed from the British AI Mark IV. Two "A" type indicators are used, one for azimuth and one for elevation. External antennas provide azimuth and elevation sensing. IFF signals displayed directly on the scope. SCR-540 operates with the SCR-640 racon. Test set IE-30 is required for maintenance.
PERFORMANCE Maximum beacon range: 100 miles. Maximum search range, 17,000 to 20,000 ft. Minimum range, 300 to 500 ft. Range accuracy, ± 10%. Azimuth limits, 70° forward on either side of line of flight. (No targets detected at ranges greater than plane's altitude.) Azimuth accuracy: right or left indication only when target is more than 5° from line of flight. Within 5° of line of flight, target will show as straight ahead. Elevation limits (at 20,000' altitude), ± 20° from forward line of flight. Elevation accuracy, same as azimuth accuracy.
TRANSPORTABILITY: Set is packaged in 7 units weighing about 225 lbs. Largest package measures 13" x 6" x 26" and weighs 32 lbs. Set is air transportable in any cargo plane.
INSTALLATION: Set is installed in P-70, Beaufighters, and A-20's. Installed weight is about 210 lbs.
PERSONNEL: One radar operator and one maintenance man are minimum requirement.
POWER: Primary power required: 40 amperes at 27.5 volts from plane's DC supply.


SCR-520-B and SCR-720-A Microwave AI Sets

SCR-520-B in P-70
SCR-520-B in P-70

The SCR-520-B is a microwave AI equipment scanning the forward 180°. B and C indication is provided for the operator; C indication only for the pilot. In addition, the pilot has a range indicator varied by the operator. Maximum ranges are 3, 10, and 100 statue miles. The SCR-720-A is a small package version of the SCR-520-B. Sets have provisions for IFF identification connections. Both sets work with SCR-620 racon. Test sets IE-30, IE-57, or LZ and PE-143 power equipment are required for maintenance.
PERFORMANCE: Maximum range on racon, 100 miles. Maximum range on P-38, 4 miles; on P-70, 5 miles; on PBY, 7 miles. Minimum range, 250 ft. Azimuth limits, 180° forward. Azimuth accuracy ± 3°. Elevation limits, -10° to +65°. Elevation accuracy, ± 2°.
TRANSPORTABILITY: SCR-520-B is packed in 6 units, the largest of which weighs 180 lbs. and measures 28" x 29" x 40". Total weight: 850 lbs.
INSTALLATION: The SCR-520-B is installed in P-70's. Total installed weight is approximately 600 lbs. The spinner, transmitter and modulator are mounted in the nose. The SCR-720-A will be installed in P-61 airplanes. Installed weight is about 412 lbs.
PERSONNEL: One radar operator and one maintenance man per set are minimum requirement.
POWER: Primary power required: 125 amperes at 27.5 volts from plane's DC supply.


AIA Microwave Set for Single-Seated Fighters

AIA in F4U
AIA in F4U

DESCRIPTION: Airborne interception set for single-seated nightfighters.
USES: Used to detect and intercept enemy aircraft in fleet operations and in attacks against fixed bases. Designed to work in connection with SM or any GCI set, and has provisions for operating with AN/CPN-6 racon, and for IFF identification connections. Provides range, bearing and relative elevation data, and b, modified H or G indications, all appearing on a single scope.
PERFORMANCE: Detects plane at maximum reliable range of 3 miles and tracks target to 360 ft. Range accuracy is ± 10% on racon, ± 5% in tracking, and ± 25 yds. in gun-laying. Covers ± 60° forward in bearing and elevation. Bearing accuracy is ± 3° on racon, ± 1/2° in gun-laying. Elevation accuracy is ± 3°.
TRANSPORTABILITY: Packaging for shipment is not yet standardized, but total package weight should not exceed 350 lbs.
INSTALLATION: Installed in F4U-2 and F6F-3. In F4U-2, installation weighs 310 lbs., requires removal of two machine guns, and reduces plane's top speed by 2 mph. Installation has no effect on armament or speed of F6F-3.
PERSONNEL: Set is operated by pilot. One maintenance man per set is required.
POWER: Total primary power required: (a) form combination AC-DC primary generator (NEA-3 or NEA-5) -- 30 amps., 27.5 V, DC and 1050 watts, 115 V, 400-2400 cycles AC; or (b) from primary DC generator, requiring use of motor-alternator (800-1-B) -- 91 amps., 27.5 V DC.


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