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보/고/서

ATIS INTERROGATION REPORT NO. 3539　23 February 1951

FIELD REPORT (ADVATIS 026)　12 February 1951

Cooperative, memory good. Occasional contradictory statements. Reliability - Poor to Fair.

Legend to sketch

Point 1a, 1b, 1c, 1d. 4 X 37mm AA guns.

2a, 2b. Base range finders.

3. Steel RR brigade 100 m long with girders 5 m high. Seven concrete piles in river at 20 m intervals.

4. Ferry boat length 5 m. Used since bridge (point 5) was broken.

5. Concrete vehicle bridge; partially destroyed with seven piers at 20 m intervals. Distance from RR bridge to broken bridge 500 m.

6. YANGSU-RI (兩水里) village; 40 km northeast of SEOUL. RR bridge 500 m away.

7. One lane dirt road leading to SEOUL.

8. Farm houses 300 m away from guns.

Railroad is single track line.

2,000 m to bend in HAN River from gun position and base of 600 m mountain 4 km to northwest of guns.

Right gun 300 m from RR bridge.

(2a) is 10 m from (1a) and (1b).

(2b) is 25 m from (1c) and (1d).

Entire area is farm land.

b. No information available on computer. “CHIKIGU” (指器具) is possible nomenclature for either computer or director. PW heard that CHIKIGU (指器具) was produced in USSR.

(1) 37mm AA Gun M1939, is used in PW battery.

(2) PW heard that gun is produced in USSR.

(3) Tank HE ammo is used in 37mm gun.

(4) Ammo was marked with paint on head of round. White head used as FLAK and black head as Anti-Tank. Shells were semi-fixed type and two clips of five rounds each were inserted from top.

(5) Velocity of ammo: 880 m/sec.

(6) 4 X 37mm AA guns per Battery

(7) Gun crew, 8 men including gun crew chief.

(8) Gun crew’s duties as follows:

(a) Crew Chief - Gives verbal commands and determines speed of aircraft by binoculars (methods unknown); and relays distance to aircraft from spotter who is centrally located in Battery. Spotter’s method of computing distance to aircraft unknown.

(b) Horizontal sighter - Sights by cross-hairs.

(c) Vertical sighter - Sights by cross-hairs.

(d) Distance and velocity operator - Operates two dials (see sketch below).

Distance dial - Calibrated from zero to 4,000 m at 200 m intervals in meter system.

Velocity dial - Calibrated from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10 to 50 at 5 intervals, at 10 intervals from 50 to 100, and at 20 intervals from 100 to 140. Dial is meter/sec scale basis.

DISTANCE DIAL　Diameter: 3 3/4”.

Scale evenly spread, scale lines are curved. Dial turns by a crank. Stationary indicator upper left quad.

VELOCITY DIAL　Diameter: 4”

Stationary indicator upper left quad. Logarithmic scale decreasing as number increases. Dial turns by a crank.

(e) Direction and elevation operator - Operates a complex dial (see sketch below).

Direction dial - A double disc instrument both calibrated from 1 to 59. These discs counter-rotate.

Elevation dials - Two located on direction dial knob. Dial graduated from plus 70° to zero degree to minus 70° at 10° intervals.

1. Knob

2. Inner scale

3. Outer scale

4a. Needle for inner scale.

4b. Needle for outer scale.

5. Aft section of knob. Knob of direction dial is aligned with the flight of aircraft. (Pt #5 aft section) corresponds to tail assembly of a/c.)

6. Elevation dial crank. Diameter: 5”

7. Elevation dial.

Numbers evenly spaced on both dials from zero to 59.

1. Crank to turn needle of elevation dial.

2. Elevation dial - 2 dia, 70° to 0° to -70° at 10° intervals.

3a, 3b. Needles for outer, inner scale of direction dial. (Elevation dial on both sides of direction dial knob)

(f) Ammo-loader. Inserts a clip of 5 rounds from the top of the gun.

(g) Ammo carrier.

(h) Ammo carrier.

Gun fires when (2) and (3) sight target and press individual foot pedals. Both pedals must be pressed before gun fires.

(9) 37mm AA guns are drawn by vehicles.

(10) 30 sec required to go into action from stationary position. PW thinks that it requires 2 or 3 minutes to go into action when traveling.

(11) Fire rats of 37mm AA gun: 160 - 180 rounds/minute.

(12) Type fuse used on 37mm unknown. Round fired by firing pin. PW saw red streaks (tracers) to half the height of shell’s ascent.

(13) Maximum range of 37mm AA gun is 6,700 m.

(14) 37mm AA gun can be used for ground targets.

(15) “FLAK” bursts were all around aircraft, but PW never observed aircraft downed by AA gunnery.

Organizational breakdown:

For the Commanding Officer: