FIXED GUN AIR FIRING - PARTS 1 2 AND 3 [Main Title]

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  • Title: FIXED GUN AIR FIRING - PARTS 1 2 AND 3 [Main Title]
  • Film Number: AMY 138
  • Other titles:
  • Summary: A training film for pilots focusing on how to use the gun-sight in battle conditions. The technical aspects of the actual mechanism is left to the armourers, whose job is the maintenance and supply of ammunition, and is not dealt with here. Very effective use made of animated technical diagrams, incorporating much numerical data for assimilation by the pilot if they are to score hits on an enemy aircraft.
  • Description: Reel one: “The reflector gun-sight mark 2”: Film opens to a photograph of the gunsight, with close up views of the controls. An illuminated sighting ring of fixed size is projected onto a sloping glass screen placed in the pilot’s forward line of vision. “The optical system”: Explanation of system. Sheet of glass in pilot’s vision, a feature of all reflector sights. The effect of gravity; bullets fall down as they progress towards the target. “The curve of pursuit”: For a crossing target the pilot must curve towards the target, in the direction of the target’s flight path. This is curve of pursuit, introducing the problem of deflection. Diagrams. “Deflection”: The pilot aims ahead of the target by the deflection angle, which he has calculated and adjusted the gun-sight controls to suit. “Angle off”: Is the angle between the pilot’s line of sight and the target’s line of flight. Pilot can fly straight ahead whilst maintaining a steady aim. “Beam view”: Between the Maximum deflection (beam view) and no deflection (stern view) are an infinite variety of intermediate stages. The use of publication 2343, a collection of charts for all types of enemy aircraft showing the form of the aircraft in different attitudes and the corresponding amount of angle off required for interception by the pilot’s bullets. Charts for Ju88, Me109F, Fw190 seen. “Target speed”: An angle of deflection requires an allowance for the target speed, and is determined by sighting through the range ring. “Standard rules”: Are given for the average attack. Explanation of the rules. “Estimation of range without the use of range bars”: Alternative when target is well off centre of the range ring; the diameter of the ring is 35 feet. when the range is 100 yards. for the average fighter aircraft. Thus calibrated, the pilot can make a judgement within the fixed ring. Explained with diagrams. Reel two: The narrative so far has ignored the effects of gravity and air resistance. The assumption, incorrectly, has been made that the bullet travels in a straight line with the velocity it was fired. “Gravity drop”: Account must be made for gravity because the bullet drops below the axis of the gun barrel. Table of distance versus bullet drop is consulted by the pilot. Diagrams. “Air resistance”: The air resistance causes a progressive slowing of the bullet due to air pressure at the nose of the bullet, and a partial vacuum created at the base, the effect is to increase the time taken to reach the given range. Known as time lag. Explained. The effect decreases with height due to the varying air density encountered. Tables and numerical examples given. “Air resistance and gravity drop”: Explained. Ground level versus height. Animated diagrams. “The line of sight”: As the pilot’s eye follows the bullet’s trajectory, a new line of sight is required for every change of range. “The cone of fire”: A single bullet exiting the barrel will not cause the gun to vibrate. Continuous firing as one bullet travels down the barrel before it’s predecessor has left the muzzle causes the gun to vibrate, and the emerging bullets to have slightly different paths. This divergence is known as the cone of fire, and can be useful for the wider coverage for the line of firing. Diagram. “Harmonisation”: When the gunsight ,the line of fire and the cine gun cameras, are aligned to meet at a certain range, they are said to be harmonised at that range. Demonstration of aircraft on the ground firing into a butt. The four gun barrels are aligned so that the four mini-cones are merged into one larger cone at the harmonisation range chosen. “The bullet group”: A cross section of the area of fire taken at any range is known as the total bullet group. 75% of bullets fired are placed into a circle half the diameter of the bullet group. This inner area is known as the 75 group, with fairly even distribution and is commonly referred to as the bullet group. Outside this area bullets are more widely spaced and are not considered in the sighting problem. “The bullet pattern”: Multi-gun aircraft are so harmonised the individual bullet groups form a predetermined bullet pattern. Explanation with multiple diagrams of different bullet pattern, dependant upon the size of enemy aircraft. Command HQ specifies firing at close range to maximise bullet density. Reel 3: “Air firing by fixed gun fighters. Sighting exercises”: “Introduction”: This part of the film is based upon the gunnery for instructor’s course at the Central Gunnery School. The exercises employed are for sighting practice only, and the methods shown should not be seen as having any tactical value. The attacks are made on drones, so only the cine-camera guns are fired in an attack. Cut to film being loaded into camera-gun. After the exercise the exposed film is removed, viewed and credited by the gunnery instructor. Process explained in detail. Animated diagrams/close up photography used extensively for the seven exercises that follow. “Exercise 1. Range estimations”: Use of range bars. Repeated without range bars to enable pilot to assess by eye. The importance of range in combat is emphasised. The majority of successful combats are within a 250 yd. Range. “Exercise 2. Range and line of sight”: In combat the pilot should position his aircraft so that the target is moving towards the spot in his reflector sight, maintaining the target within the reflector sight as it closes to the pilot. Filmed examples of instructors approaching from different angles whilst maintaining target within the sight. “Exercise 3. Steady deflection, target turning”: Filmed examples, flown by the instructors. “Exercise 4. Quarter attacks”: The quarter attack is the basis for all deflective shooting, and assumes the enemy is flying straight and level. "Approach from opposite course. Approach from parallel course”: Both approaches require the pilot to position himself such that the target ultimately fills his circular sight, thus enabling a kill. Reel four: “Approach from overhead. Exercise 5. Approach from below. Exercise 6. An advanced exercise in steadiness and range estimation) Astern overtaking attacks. Exercise 7. Jumping and evading. All the exercises are demonstrated by the flying instructors. Throughout the series of exercises, the actions of the instructors are interspersed with the actual view as would be seen by the pilot through the gun-sight. An effective combination, with a precise narrative. Film closes with actual battle shots, aircraft on fire, exploding, moving rapidly around, and crashing, with the commentary concluding: to be a good gunner requires good aircraft control, rapid reactions and familiarity with the various types of attack formation.
  • Alternative Title:
  • Colour: B&W
  • Digitised:
  • Object_Number: AMY 138
  • Sound: Sound
  • Access Conditions:
  • Featured Period: 1939-1945
  • Production Date: 1944
  • Production Country: GB
  • Production Details: ROYAL AIR FORCE (Production sponsor) Science Films (Production company)
  • Personalities, Units and Organisations:
  • Keywords:
  • Physical Characteristics: Colour format: B&W Sound format: Sound
  • Technical Details: Format: 35mm Number of items/reels/tapes: 4 Length: 3333ft
  • HD Media:
  • Link to IWM Collections page:

    AMY 138

  • Related IWM Collections Objects:

    AMY 204 (TRACER METHOD OF AIR SIGHTING [Main Title])
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