Air gunner course notes
Title
Air gunner course notes
Description
Covers air gunners course including sighting, gun ranges, characteristics of machine guns, bullet patterns, harmonisation, firing techniques, use of tracer rounds and gun turret hydraulics. Front Cover captioned '1880966, AQC Allen, Class No 0, Hut 15, Pembrey, Course 94'.
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10 page notebook with front and rear cover
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This content is available under a CC BY-NC 4.0 International license (Creative Commons Attribution-NonCommercial 4.0). It has been published ‘as is’ and may contain inaccuracies or culturally inappropriate references that do not necessarily reflect the official policy or position of the University of Lincoln or the International Bomber Command Centre. For more information, visit https://creativecommons.org/licenses/by-nc/4.0/ and https://ibccdigitalarchive.lincoln.ac.uk/omeka/legal.
Identifier
MAllenDJ1880966-150702-04
Transcription
[underlined] 1880966. A.C. ALLEN.
CLASS. No 9. HUT 15
PEMBREY. COURSE 94 [/underlined]
[page break]
SIGHTING.
THE REFLECTOR SIGHT.
It is an illuminated ring and bead sight.
(a) The bead shows you where your bullets are going
(b) The ring is a scale to measure allowances (RADS) and is the only way of estimating range of target
Changeing [sic] bulb. (After 30hrs use or blackening).
(a) by day. polarity marks coincide.
(b) by night. by trial and error. If incorrect dim light by "day", no light by "night".
Keep all glass surfaces (5) clean and free from smears, "chamois leather".
ADJUSTMENTS.
1. To move sight laterally, loosen split collar.
2. To move sight for elevation or depression, loosen nut opposite end to split collar. ie. by the cam.
If sight refuses to function check master switch, fuze [sic] and accumulator leads
RANGE ESTIMATION.
[graph for range estimation]
[page break]
KEY RANGES.
600yds Limiting Range
400yds Effective Range.
150yds Point blank.
[underlined]CHARACTERISTICS OF M/G FIRE. [/underlined]
1.Cone of fire.
The space which contains the trajectories of all the bullets fired
2. Bullet Group. - cross section of cone of fire 15' diameter at 400yds
3. Bullet pattern - two or more bullet groups caused by vibration of mountings and whip of the barrel
[underlined] GRAVITY DROP. [/underlined]
The distance the bullet falls below the axis of the barrel due to the pull of the earth.
[ Diagram showing gravity drop effects]
It is allowed for by
[underlined] HARMONISATION. [/underlined]
It is the aligning of the guns with the sight to allow for gravity drop.
[page break]
[underlined] BULLET PATTERN FOR 4 GUNS [/underlined] [underlined] 15' DIA @ 400yds [/underlined]
[ two diagrams showing this]
[underlined] PROCEDURE FOR HARMONISATION. [/underlined]
1. Lock turret in fore and aft positions.
2. Remove Breech block and back plate etc.
3. Place harmonisation board correct distance in front of guns so that master gun (BOTTOM LEFT) is aligned on its appropiate [sic] gun spot.
4. Align remaining guns on their appropiate [sic] spots one at a time checking with the master gun after each operation.
5. Align sight on sight spot.
6. Unlock turret operate in all directions, relock and recheck.
[underlined]NOTE. [/underlined] Mid upper turrets are harmonised on the port beam
To ensure greater accuracy in aligning the guns it is advisable to strip a
[page break]
breech block, replace it in gun and sight through firing pin hole.
[underlined] BULLET TRAIL [/underlined]
Is the lagging behind of a bullet along its path due to air resistance. It is influenced by height, range, speed of own a/c, and angle of fire. (allowance is maximum on the beam decreasing to nil ahead or astern). It is allowed for by moving your guns towards the nose of your own a/c.
[diagram to illustrate]
[ Bullet trail table]
[underlined] PARRALELL[sic] COURSE SHOOTING. [/underlined]
1. [underlined] SAME SPEED.[/underlined]
Allow for bullet trail only.
2. E/A FASTER
Aim two Rads in front.
3. E/A SLOWER.
Aim point blank.
[page break]
[underlined] CORRECTING ON TRACER. FIGHTERS ATTACK. [/underlined]
Estimates your speed to find his allowance
1. parallel course 1200yds/800yds (to get your speed)
2. Banks "cockpit towards ) sighting
3. Banks opposite way "GUNS ON"
During "double bank" Pt Blank Shot, fire long burst.
[ diagram curve of pursuit]
[ diagram the zone method]
Aiming point being between the target and your own tail.
[page break]
[underlined] Correcting on Tracer. [/underlined]
TRACER.
It is an illuminated bullet. - 2 kinds
G IV - day tracer - burns brightly from -0yds - 600yds.
G V - night tracer - burns dull from -0yds - 200yds brightens 200yds - 600yds.
It is a secondary aid to sighting. It shows you correct "Line" and correct allowance.
YOU CANNOT ESTIMATE RANGE WITH TRACER.
RULES OF AIMING AGAINST CURVE OF PURSUIT.
USING TRACER.
1. Recognise the a/c.
2. Estimate Range.
3. Make the necessary zone[?] allowance towards own tail.
4. At 600yds fire a burst and note end of trace (It is essential that you maintain the target in the same position in your sight whilst firing).
5. Keep firing with the target at the end of the trace.
6. At 400yds position target half way along the existing trace.
7. Keep firing with target half way along the trace until 150yds. Then fire point blank until the break away.
[page break]
8. On break away build up deflection of 1 Rad in the direction of the breakaway firing cont.
FRONT GUNNER.
1. Head On - P.t. Blank - 1200yds
2. Head On "Up" - Shallow Dive - 1200yds - 1 Rad above and increase.
3. Head On "Down" Shallow climb - 1200yds - 1 Rad below.
[diagram to illustrate]
[underlined] GROUND STRAFFING.[sic] [/underlined] under 2000'
[underlined] FRONT GUNNER [/underlined] - 1000yds - fires 2 Rads short of target increasing to 3.
[underlined] REAR GUNNER [/underlined] 3 RADS and decreases
[underlined] TRACER. - should enter the target.
[underlined] PRE [/underlined] FLIGHT INSPECTION.
1. Switch on master switch.
2. Check sight (switch) in all positions
3. If sight does not light (a) change bulb (b) Check fuze[sic] (c) check leads
4. Check spare bulbs and fuzes. [sic]
5. Check sight mounting for security.
6. Wipe all glass surfaces.
[page break]
CORRECT RULE FOR USING TRACER.
Keep the sight moving with the target before firing, during firing, and as long after firing as trace is visible. Watch the end point, [underlined] if [/underlined] this is done the trace ( from sight centre to end of trace) gives the correct deflection including bullet trail for 600 yds.
BREAKAWAY'S. [sic]
Breakaway [underlined] down [/underlined], (rear and mid upper).
Aim 1 Rad along line of breakaway, firing continuosly [sic] until fighter has passed through sight. [underlined] Front gunner [/underlined]
Aim 2 Rads over the outside shoulder of target
[underlined] Break away up, [/underlined] rear gunner, as for break away down.
Mid Upper and Front gunner, aim point blank.
[page break]
Bristol turret 60o either side
Elevation 60o
Depression 32o
Independant [sic] gun rotation 40o either side of any mid position. Working pressure of turret 600lbs per squ inch.
REARMING.
Double link in tank,[?] single link to right hand gun.
Single link in Left hand tail.[?] double link to left hand gun.
The hydraulic lock is to prevent gun sinkage.
[diagram (upside down)]
[page break]
[diagram of Bristol a/c hydraulic and turret layout.]
CLASS. No 9. HUT 15
PEMBREY. COURSE 94 [/underlined]
[page break]
SIGHTING.
THE REFLECTOR SIGHT.
It is an illuminated ring and bead sight.
(a) The bead shows you where your bullets are going
(b) The ring is a scale to measure allowances (RADS) and is the only way of estimating range of target
Changeing [sic] bulb. (After 30hrs use or blackening).
(a) by day. polarity marks coincide.
(b) by night. by trial and error. If incorrect dim light by "day", no light by "night".
Keep all glass surfaces (5) clean and free from smears, "chamois leather".
ADJUSTMENTS.
1. To move sight laterally, loosen split collar.
2. To move sight for elevation or depression, loosen nut opposite end to split collar. ie. by the cam.
If sight refuses to function check master switch, fuze [sic] and accumulator leads
RANGE ESTIMATION.
[graph for range estimation]
[page break]
KEY RANGES.
600yds Limiting Range
400yds Effective Range.
150yds Point blank.
[underlined]CHARACTERISTICS OF M/G FIRE. [/underlined]
1.Cone of fire.
The space which contains the trajectories of all the bullets fired
2. Bullet Group. - cross section of cone of fire 15' diameter at 400yds
3. Bullet pattern - two or more bullet groups caused by vibration of mountings and whip of the barrel
[underlined] GRAVITY DROP. [/underlined]
The distance the bullet falls below the axis of the barrel due to the pull of the earth.
[ Diagram showing gravity drop effects]
It is allowed for by
[underlined] HARMONISATION. [/underlined]
It is the aligning of the guns with the sight to allow for gravity drop.
[page break]
[underlined] BULLET PATTERN FOR 4 GUNS [/underlined] [underlined] 15' DIA @ 400yds [/underlined]
[ two diagrams showing this]
[underlined] PROCEDURE FOR HARMONISATION. [/underlined]
1. Lock turret in fore and aft positions.
2. Remove Breech block and back plate etc.
3. Place harmonisation board correct distance in front of guns so that master gun (BOTTOM LEFT) is aligned on its appropiate [sic] gun spot.
4. Align remaining guns on their appropiate [sic] spots one at a time checking with the master gun after each operation.
5. Align sight on sight spot.
6. Unlock turret operate in all directions, relock and recheck.
[underlined]NOTE. [/underlined] Mid upper turrets are harmonised on the port beam
To ensure greater accuracy in aligning the guns it is advisable to strip a
[page break]
breech block, replace it in gun and sight through firing pin hole.
[underlined] BULLET TRAIL [/underlined]
Is the lagging behind of a bullet along its path due to air resistance. It is influenced by height, range, speed of own a/c, and angle of fire. (allowance is maximum on the beam decreasing to nil ahead or astern). It is allowed for by moving your guns towards the nose of your own a/c.
[diagram to illustrate]
[ Bullet trail table]
[underlined] PARRALELL[sic] COURSE SHOOTING. [/underlined]
1. [underlined] SAME SPEED.[/underlined]
Allow for bullet trail only.
2. E/A FASTER
Aim two Rads in front.
3. E/A SLOWER.
Aim point blank.
[page break]
[underlined] CORRECTING ON TRACER. FIGHTERS ATTACK. [/underlined]
Estimates your speed to find his allowance
1. parallel course 1200yds/800yds (to get your speed)
2. Banks "cockpit towards ) sighting
3. Banks opposite way "GUNS ON"
During "double bank" Pt Blank Shot, fire long burst.
[ diagram curve of pursuit]
[ diagram the zone method]
Aiming point being between the target and your own tail.
[page break]
[underlined] Correcting on Tracer. [/underlined]
TRACER.
It is an illuminated bullet. - 2 kinds
G IV - day tracer - burns brightly from -0yds - 600yds.
G V - night tracer - burns dull from -0yds - 200yds brightens 200yds - 600yds.
It is a secondary aid to sighting. It shows you correct "Line" and correct allowance.
YOU CANNOT ESTIMATE RANGE WITH TRACER.
RULES OF AIMING AGAINST CURVE OF PURSUIT.
USING TRACER.
1. Recognise the a/c.
2. Estimate Range.
3. Make the necessary zone[?] allowance towards own tail.
4. At 600yds fire a burst and note end of trace (It is essential that you maintain the target in the same position in your sight whilst firing).
5. Keep firing with the target at the end of the trace.
6. At 400yds position target half way along the existing trace.
7. Keep firing with target half way along the trace until 150yds. Then fire point blank until the break away.
[page break]
8. On break away build up deflection of 1 Rad in the direction of the breakaway firing cont.
FRONT GUNNER.
1. Head On - P.t. Blank - 1200yds
2. Head On "Up" - Shallow Dive - 1200yds - 1 Rad above and increase.
3. Head On "Down" Shallow climb - 1200yds - 1 Rad below.
[diagram to illustrate]
[underlined] GROUND STRAFFING.[sic] [/underlined] under 2000'
[underlined] FRONT GUNNER [/underlined] - 1000yds - fires 2 Rads short of target increasing to 3.
[underlined] REAR GUNNER [/underlined] 3 RADS and decreases
[underlined] TRACER. - should enter the target.
[underlined] PRE [/underlined] FLIGHT INSPECTION.
1. Switch on master switch.
2. Check sight (switch) in all positions
3. If sight does not light (a) change bulb (b) Check fuze[sic] (c) check leads
4. Check spare bulbs and fuzes. [sic]
5. Check sight mounting for security.
6. Wipe all glass surfaces.
[page break]
CORRECT RULE FOR USING TRACER.
Keep the sight moving with the target before firing, during firing, and as long after firing as trace is visible. Watch the end point, [underlined] if [/underlined] this is done the trace ( from sight centre to end of trace) gives the correct deflection including bullet trail for 600 yds.
BREAKAWAY'S. [sic]
Breakaway [underlined] down [/underlined], (rear and mid upper).
Aim 1 Rad along line of breakaway, firing continuosly [sic] until fighter has passed through sight. [underlined] Front gunner [/underlined]
Aim 2 Rads over the outside shoulder of target
[underlined] Break away up, [/underlined] rear gunner, as for break away down.
Mid Upper and Front gunner, aim point blank.
[page break]
Bristol turret 60o either side
Elevation 60o
Depression 32o
Independant [sic] gun rotation 40o either side of any mid position. Working pressure of turret 600lbs per squ inch.
REARMING.
Double link in tank,[?] single link to right hand gun.
Single link in Left hand tail.[?] double link to left hand gun.
The hydraulic lock is to prevent gun sinkage.
[diagram (upside down)]
[page break]
[diagram of Bristol a/c hydraulic and turret layout.]
Collection
Citation
D J Allen, “Air gunner course notes,” IBCC Digital Archive, accessed April 19, 2024, https://ibccdigitalarchive.lincoln.ac.uk/omeka/collections/document/2215.
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