John Taplin's Air Cadet Notes
Title
John Taplin's Air Cadet Notes
Description
John's notes recorded when he was an air cadet. It includes the Browning Gun, Sighting, the VGO Gun, the Reflector Sight, the Frazer Nash Turret and Boulton Paul turret.
Creator
Coverage
Language
Format
21 page booklet of handwritten notes
Publisher
Rights
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
MTaplinJA1268696-161130-01
Transcription
[notebook front outer cover – blank page]
[page break]
J A. TAPLIN LAC. 1268696
AIR CADET OF PENRHOS No 9 A.O.S.
JOHN A TAPLIN
33 GREYDELLS RD
STEVENAGE
HERTS
SG1 3NJ
[page break]
[underlined] The Browning Gun. [/underlined]
[underlined] General Description [/underlined]
Weight with loading mechanism and special Trigger motor (14 ozes) [sic] is 22 lbs 12 ozes. [sic]
Overall Length with flash eliminator 3' – 8 1/2"
Length of barrell [sic] 24 inches
5 grooves left hand twist turn 1 in 10.
Rate of fire 1150 RPM.
[underlined] Recoil Action [/underlined]
Unlocking of Breech
Action of acceleration
Backward movement of Breech Block during which the following takes place.,
First action of feed
Compression of Return Spring
Action of Locking Lever
Extraction & Ejection
Engagement of rear sear.
[page break]
[underlined] The Recoil action in detail [/underlined]
At the moment of the explosion the barrel & the barrel extension and breech block, recoil as a single unit for about 5/16th an inch this ensures that the bullet has left the barrel before the BB is unlocked from the barrel extension. The locking piece now rides down its cam, positive action being assured through the engagement of the prongs of the frame with the locking piece pin. The BB is freed from the barrel extension and is enabled to continue its recoil movement independly [sic]. The recoil of the barrel causes the ‘T’ shaped projection on the barrel extension to engage the plunger and compress the barrel return spring at the same time the barrel extension pushes the accelerator, upwards backwards and over centre, until its two ramps are interlocked with the front face of the ‘T’ shaped projection, this locks the barrel extension to the locking frame against the pressure of the
[page break]
barrel return spring, as the accelerator rotates its horns strike against the rear sear bent on the breech block. This accellerating [sic] it sharply to the rear. The BB is moving to the rear compresses the return spring and causes the cocking lever through its engagement with the bracket of the top plate to swing forward and withdraw the firing pin. The sear ends the action of its spring rides over the bent of the firing pin, ready for engagement as soon as the breech block starts to ride forward. At the same time a live round which is gripped, the claw of the transporter and is supported by the ejector is withdrawn from the belt and carried by the transporter to the rear also the BB. As it moves away from the barrel extracts the empty cartridge case from the chamber. The empty case may fall from the BB, but if it is not, it will be ejected at a later stage on reaching the end of the rear cam of the side plate the transporter is forced down by the ramp on the Breech cover this action brings the live round
[page break]
of the feed pawl with the round. Double feed is prevented by the feed pawl leg and the round is brought into position against the bullet and cartridge stops ready to be gripped by the transporter at the same time a fresh round [deleted] a [/deleted] is brought over and engaged by the retaining pawl under the action of its spring as each round is withdrawn by the transporter, the clip falls and ejected the opposite side to the feed entrance.
[underlined] The Rear Sear Mechanism [/underlined]
When the firing control is opperated [sic] the plunger of the rear sear release which engages the rear sear lever causing it to rotate and depress the rear sear until the bent is below the lock frame plates this allowing the breech block to go freely forward. When the firing control plunger is released the plunger of the rear sear release unit is withdrawn and a compressed rear sear spring raises the rear sear as the BB recoils it rearwards depression and overrides the rear sear. Which again rises and engages the bent of the BB
[page break]
as it rebounds off the buffer of the back plate. The engagement of the two bents carries the rear sear forward which causes the rear sear cradle to rotate and compressess [sic] the sear buffer spring so absorbing the blow.
[underlined] The Firing Mechanism [/underlined]
At the end of the forward of the recoiling portions the the [sic] sear meets the projecting plunger of the fire & safe unit or trigger motor which ever is fitted and forced out of engagement with the bent on the firing pin. The firing pin spring is then released, asserts itself and forces the firing pin forward to strike the cap of the cartridge in the chamber & fire the round.
[underlined] Safety Units [/underlined]
[circled 1] [underlined] The locking of the Breech [/underlined]
The locking piece lever is 5/16” before the BB is fully forward.
[circled 2] [underlined] The Rear Sear. [/underlined]
Prevents the poss of a cooked round
[page break]
[underlined] The locking lever [/underlined]
Releases the firing pin gentley [sic], gentley [sic] enough & prevent round from being fired if the sear is broken.
[underlined] Fire & Safe Unit [/underlined]
So positioned on the side of the gun that the BB must be fully forward and in the locked position before the gun can be fired.
[underlined] General Notes [/underlined]
Position of eye can give an error of 4 to 6 feet.
Parralax [sic] error 13' – 15' ft
Accomadation [sic] of the eye.
[drawing]
[page break]
[blank page]
[page break]
[underlined] Sighting [/underlined]
Muzzle velocity 2440 ft per sec.
Average velocity 2200 ft per sect [sic].
[underlined] Method of Construction of 50 MPH. Relative Speed ring. [underlined]
[diagram] [calculations]
[page break]
If [symbol] the relative speed of a/c is 50 MPH its velocity in seconds is 73 feet per second the sight base being 20° the average velocity being 2200 feet per second the radius of the sight ring can be found thus.
[calculations]
[underlined] Range Estimation [/underlined]
Range of an a/c can be judged with the aid of the ring sight [missing word] the wing span of a/c is known. If the a/c fills the ringsight [sic] and the wing span of a/c is said to be 30 ft add a 0 and ÷ by 2 = 150 yds.
[underlined] Approx wing span of a/c of various types [/underlined]
Single Seat fighter 30 ft.
Light Bomber 50 ft. Heavy Transport 90 ft to 100 ft
Heavy Bomber 70 – 80 ft
[page break]
[underlined] Sighting Contd. [/underlined]
When a/c is flying through sight, place a/c on edge reciplical [sic] of the direction of flight.
[diagram]
Always place a/c so that it is flying towards the centre of sight ring.
[page break]
[underlined] Breeching Up [/underlined]
The reason for breeching up is to give the cartridge head space.
Under breeching gives you a seperated [sic] case because there is insufficient support to the case.
Considerably over breeching, the gun does [inserted] NOT [/inserted] fire, because the breech block does not go far enough forward as the sear is not released by the fire-safe unit.
Slightly over breeched, causes friction between Locking piece [symbol] locking recess.
When changing feed, see that all parts are adjusted to one feed.
[page break]
[notes/abbreviations]
[page break]
[blank page]
[page break]
[underlined] The VGO Gun [/underlined]
[underlined] General Description [/underlined]
Length of gun 40"
Barrel 20"
Weight 20 lbs
Rifling left twist 1-10
5 grooves
Feed; Magazine, 60 and 100 rounds.
Speed 950 RPM
[underlined] To load gun [/underlined]
Switch to S (Safe) pull back cocking lever and return to its original position. Switch to Fire position (circled i) . Place Mag on rear catch, first, position body, press down to engage on front catch, and give upward pull to ensure security.
[circled i] When Mag is in place and properly secured.
[page break]
[underlined] Cocking By Hand [/underlined]
On Cocking handle being pulled backwards, the CH catch is disengaged from the recess in body of the gun, and allows CH too [sic] be drawn to rear. CH. engages against rear of of [sic] the slot on left hand side of piston rod. The piston rod is thus drawn to rear carrying with it the Breech Block, till bent on piston rod is engaged by sear. During this movement of the piston rod, the rear sear [indecipherable word] the cocking handle must now be returned to Fire position, the gun is then ready to fire
[underlined] Forward Action [/underlined]
(a) When trigger is pressed the short arm forces trigger forward and compresses trigger spring. The forked for [sic] end of trigger rod being engaged against lower arms of sear rotates out its own axis pin compressing sear spring & withdrawing nose of sear bent on the underside of Piston Rod. Meanwhile as [missing words] move forward, sear
[page break]
is rotated under the action of its spring, the arms engage over step of sear. When nose of sear is disengaged from the bent of Piston Rod, Piston Rod is forced forward by compressed return springs carrying with it the BB.
(B) Feeding of Round in Magazine to chamber
As BB moves forward the Firing Pin engages against base of cartridge; under the influence of the bullet guide (which) guides bullet into chamber, then deflects base of cartridge down to face of BB where it is engaged by extracter [sic]. The final forward movement of BB forces cartridge fully home into chamber
[underlined] Action of Magazine [/underlined]
Insured [sic] each cartridge is clear of lips of mag remainder of cartridges in mag rear move round bodily by action of main spring acting on top plate until next round is positioned in mag lips ready for next feed movement. Piston Rod bears against
[page break]
[blank page]
[page break]
[drawing]
[page break]
[blank page]
[page break]
[blank page]
[page break]
[drawing] [calculations]
[page break]
[underlined] The Reflector Sight [/underlined]
The advantages of the reflector sight
A. Position of eye is not critical
B. No lining up of sight, in ring & head.
C. Both eyes should be kept open
D. Can be used against sun
E. Can be used at night
[underlined] Disadvantages [/underlined]
A. Electrical
B. fragile
C. Expensive
D. Hood partially obscures vision
E. Condensation of reflector glass.
[diagram and key]
[page break]
[underlined] Gravity Drop. [/underlined]
Gravity drop is the force of gravity acting on the bullet.
Bullet drop is always greatest at the horizontal round the aircraft
[diagram and calculations]
[page break]
[underlined] Tracer Sighting contd [/underlined]
1 Recognise & identify a/c
2 – Estimate range RS.
3 – When a/c is approx. 400 yds, position a/c in centre of sight and fire a short burst (sighter burst). Still keeping a/c in RS. note end of tracer in relation to RS.
4 – Allowances depend on type of tracer used.
[underlined] Using G1 [/underlined]
Position a/c on end point of trace & maintain this aim until a/c closes to range approx. 150 yds then fire point blank.
[underlined] Using G2 [/underlined]
This tracer extinguishes 1200 yds. End point unreliable. (If the end point of tracer is inside) ring fire point to blank at all ranges. If end point is outside ring sight position a/c 1/2 - 2/3 of radius of ring along the tracer. Maintain and same as G1.
[page break]
[underlined] Using G4 [/underlined]
This extinguishes at 600 yds, position a/c 1/2 along trace & finish as before.
[underlined] Advantages of Tracer Sighting [/underlined]
[circled 1] Sighting reduced to (wide) rule of thumb method.
[circled 2] No allowance has to be made for gravity drop, because sights are harmonized with gun. You see where bullets are going also proving the point.
[circled 3] Trace tells of deflection or if deflection shot is required, and indicates what allowance should be made. G1 & G4 give indication of amount of deflection required.
[circled 4] Attacker can see bullets and is disconcerted [inserted] perhaps?!!!! [/inserted]
[page break]
[underlined] Disadvantages of Tracer Sighting [/underlined]
Trace gives immpression [sic] target is being hit whether the amount of deflection is a little, correct, or too great.
There is a tendency to use trace by hose piping method.
At night it may dazzle gunner so target is obscured.
Owing to rapid reduction in the brilliance of the light source bullets appear to go more quickly & appear to be further away at any instant than they are, infact [sic].
The advantage of surprise is eliminated when 1st burst is fired.
[page break]
[blank page]
[page break]
[blank page]
[page break]
if below, pump [indecipherable word] to 4" extension.
3 – Start up EDP and run at max revs allowed. Operate turret slowly & seperately [sic] in all directions This will displace air from the system, valve box & VOM. This air will lodge itself under the spring loaded plunger of the recuperator. STOP ENGINE.
4 – Pump up recup [sic] to its fullest extent & continue pumping until the air has been displaced through the weep holes in the recup. Then completely fil [sic] reservoir.
5 – With rams fully contracted bleed system at rear sear release pipe lines until recuperator spindle extends 4". (Should rams be left fully extended recup spindle should extend 3" only). Do not add any more oil to reservoir as the required oil/air space is now completely adjusted.
6 – Replace & tighten filler cap.
[page break]
4 – When clean oil appears at inlet side of pump tighten union, continue pumping till clean oil appears at pressure union. Tighten union.
5 – Pump up recup. until spring loaded plunger is fully extended. Continue pumping to displace air trapped under plunger.
6 – With master valve depressed, work control valves so as to fill up unit and pipes
[underlined] Bleeding [/underlined]
1st Slacken off bleeder screws at top of rams bodies, with master valve depressed operate elevation valve for ram extension. Tighten bleed screws when clean appears
1 – Slacken off bleed screws at end of ram piston-rods with master valve depressed operate EV as for ram contraction, Tighten bleed screws when clean oil appears.
2 – Check recuperator spindle height and
[page break]
[diagram]
[underlined] Bleeding & Filling [/underlined]
[underlined] Filling [/underlined]
Obtain correct oil correctly filtered.
1 – [indecipherable word] that gun rams are fully closed.
2 – Slacken of [sic] union nuts of EDP.
3 – Remove Filter cap using gauze lined funnel fil [sic] recup reservoir, at the same time working the hand pump steadily.
[page break]
[underlined] The Frazer Nash Turret. [/underlined]
[underlined] The recuperator & its duty or rather duties [/underlined]
1 – To act as a chamber of every, varying capacities or volume.
2 – Maintain at all times at low pressure of 16-20 lbs on the inlet side of the pump when the engine is running, throughout the whole system, when the engine is not running.
3 – To provide a reserve supply of oil to make good slight actual loss.
4 – To provide a means of filling and topping up the closed circuit.
[diagram]
[page break]
[blank page]
[page break]
[underlined] The Hydrolic [sic] System, Circuit [/underlined]
[diagram]
[underlined] The electrical Circuit [/underlined]
[diagram]
[page break]
the top chamber through the open bleeder valve.
(8) At the end of stroke, top up sump.
(9) leave bleeder valve open, and pump for depression.
(10) Watch for ejected oil at bleeder valve when it appears tighten valve.
(11) Elevate and depress a few times.
(12) Top up sump.
(13) Elevate guns approx. 40°
(14) Slacken off connection of Hyd [sic] Motor
(15) Operate turret for rotation
(16) Watch for ejected oil.
(17) When oil is ejected reverse rotation. Again watch for oil. Tighten union
(18) [symbol] Operate Turret in all directions
(19) Top up sump and fill up filler cap.
It is important that the force or free & engage lever is kept engaged & the pump should never be used at more than 1/2 stroke.
[page break]
[underlined] The Boulton & Paul Turret [/underlined]
[underlined] Bleeding & Filling [/underlined]
Remember [inserted] that [/inserted] at commence operations pipe lines will be filled with air, every effort must be made to force the air out as oil is pumping or rather pumped, and so prevent the possibility of air cushions – Stop turret and put guns horizontal and proceed as follows
[circled 1] Fill up sump with clean oil
[circled 2] Slacken off connection at lower end of Hyd Pump or Ram.
[circled 3] Start turret and work for elevation, oil will be pumped toward lower end of ram forcing air before it to escape at the loosed connections
[circled 4] Watch for ejected oil when it appears tighten connections
[circled 5] Top up sump.
[circled 6] Open fully, the Bleeder valve.
[circled 7] Continue to pump for elevation the piston will move upwards forcing the air from
[page break]
[notebook back inner cover – partly wrapped]
[page break]
[notebook back outer cover – wrapped]
[page break]
J A. TAPLIN LAC. 1268696
AIR CADET OF PENRHOS No 9 A.O.S.
JOHN A TAPLIN
33 GREYDELLS RD
STEVENAGE
HERTS
SG1 3NJ
[page break]
[underlined] The Browning Gun. [/underlined]
[underlined] General Description [/underlined]
Weight with loading mechanism and special Trigger motor (14 ozes) [sic] is 22 lbs 12 ozes. [sic]
Overall Length with flash eliminator 3' – 8 1/2"
Length of barrell [sic] 24 inches
5 grooves left hand twist turn 1 in 10.
Rate of fire 1150 RPM.
[underlined] Recoil Action [/underlined]
Unlocking of Breech
Action of acceleration
Backward movement of Breech Block during which the following takes place.,
First action of feed
Compression of Return Spring
Action of Locking Lever
Extraction & Ejection
Engagement of rear sear.
[page break]
[underlined] The Recoil action in detail [/underlined]
At the moment of the explosion the barrel & the barrel extension and breech block, recoil as a single unit for about 5/16th an inch this ensures that the bullet has left the barrel before the BB is unlocked from the barrel extension. The locking piece now rides down its cam, positive action being assured through the engagement of the prongs of the frame with the locking piece pin. The BB is freed from the barrel extension and is enabled to continue its recoil movement independly [sic]. The recoil of the barrel causes the ‘T’ shaped projection on the barrel extension to engage the plunger and compress the barrel return spring at the same time the barrel extension pushes the accelerator, upwards backwards and over centre, until its two ramps are interlocked with the front face of the ‘T’ shaped projection, this locks the barrel extension to the locking frame against the pressure of the
[page break]
barrel return spring, as the accelerator rotates its horns strike against the rear sear bent on the breech block. This accellerating [sic] it sharply to the rear. The BB is moving to the rear compresses the return spring and causes the cocking lever through its engagement with the bracket of the top plate to swing forward and withdraw the firing pin. The sear ends the action of its spring rides over the bent of the firing pin, ready for engagement as soon as the breech block starts to ride forward. At the same time a live round which is gripped, the claw of the transporter and is supported by the ejector is withdrawn from the belt and carried by the transporter to the rear also the BB. As it moves away from the barrel extracts the empty cartridge case from the chamber. The empty case may fall from the BB, but if it is not, it will be ejected at a later stage on reaching the end of the rear cam of the side plate the transporter is forced down by the ramp on the Breech cover this action brings the live round
[page break]
of the feed pawl with the round. Double feed is prevented by the feed pawl leg and the round is brought into position against the bullet and cartridge stops ready to be gripped by the transporter at the same time a fresh round [deleted] a [/deleted] is brought over and engaged by the retaining pawl under the action of its spring as each round is withdrawn by the transporter, the clip falls and ejected the opposite side to the feed entrance.
[underlined] The Rear Sear Mechanism [/underlined]
When the firing control is opperated [sic] the plunger of the rear sear release which engages the rear sear lever causing it to rotate and depress the rear sear until the bent is below the lock frame plates this allowing the breech block to go freely forward. When the firing control plunger is released the plunger of the rear sear release unit is withdrawn and a compressed rear sear spring raises the rear sear as the BB recoils it rearwards depression and overrides the rear sear. Which again rises and engages the bent of the BB
[page break]
as it rebounds off the buffer of the back plate. The engagement of the two bents carries the rear sear forward which causes the rear sear cradle to rotate and compressess [sic] the sear buffer spring so absorbing the blow.
[underlined] The Firing Mechanism [/underlined]
At the end of the forward of the recoiling portions the the [sic] sear meets the projecting plunger of the fire & safe unit or trigger motor which ever is fitted and forced out of engagement with the bent on the firing pin. The firing pin spring is then released, asserts itself and forces the firing pin forward to strike the cap of the cartridge in the chamber & fire the round.
[underlined] Safety Units [/underlined]
[circled 1] [underlined] The locking of the Breech [/underlined]
The locking piece lever is 5/16” before the BB is fully forward.
[circled 2] [underlined] The Rear Sear. [/underlined]
Prevents the poss of a cooked round
[page break]
[underlined] The locking lever [/underlined]
Releases the firing pin gentley [sic], gentley [sic] enough & prevent round from being fired if the sear is broken.
[underlined] Fire & Safe Unit [/underlined]
So positioned on the side of the gun that the BB must be fully forward and in the locked position before the gun can be fired.
[underlined] General Notes [/underlined]
Position of eye can give an error of 4 to 6 feet.
Parralax [sic] error 13' – 15' ft
Accomadation [sic] of the eye.
[drawing]
[page break]
[blank page]
[page break]
[underlined] Sighting [/underlined]
Muzzle velocity 2440 ft per sec.
Average velocity 2200 ft per sect [sic].
[underlined] Method of Construction of 50 MPH. Relative Speed ring. [underlined]
[diagram] [calculations]
[page break]
If [symbol] the relative speed of a/c is 50 MPH its velocity in seconds is 73 feet per second the sight base being 20° the average velocity being 2200 feet per second the radius of the sight ring can be found thus.
[calculations]
[underlined] Range Estimation [/underlined]
Range of an a/c can be judged with the aid of the ring sight [missing word] the wing span of a/c is known. If the a/c fills the ringsight [sic] and the wing span of a/c is said to be 30 ft add a 0 and ÷ by 2 = 150 yds.
[underlined] Approx wing span of a/c of various types [/underlined]
Single Seat fighter 30 ft.
Light Bomber 50 ft. Heavy Transport 90 ft to 100 ft
Heavy Bomber 70 – 80 ft
[page break]
[underlined] Sighting Contd. [/underlined]
When a/c is flying through sight, place a/c on edge reciplical [sic] of the direction of flight.
[diagram]
Always place a/c so that it is flying towards the centre of sight ring.
[page break]
[underlined] Breeching Up [/underlined]
The reason for breeching up is to give the cartridge head space.
Under breeching gives you a seperated [sic] case because there is insufficient support to the case.
Considerably over breeching, the gun does [inserted] NOT [/inserted] fire, because the breech block does not go far enough forward as the sear is not released by the fire-safe unit.
Slightly over breeched, causes friction between Locking piece [symbol] locking recess.
When changing feed, see that all parts are adjusted to one feed.
[page break]
[notes/abbreviations]
[page break]
[blank page]
[page break]
[underlined] The VGO Gun [/underlined]
[underlined] General Description [/underlined]
Length of gun 40"
Barrel 20"
Weight 20 lbs
Rifling left twist 1-10
5 grooves
Feed; Magazine, 60 and 100 rounds.
Speed 950 RPM
[underlined] To load gun [/underlined]
Switch to S (Safe) pull back cocking lever and return to its original position. Switch to Fire position (circled i) . Place Mag on rear catch, first, position body, press down to engage on front catch, and give upward pull to ensure security.
[circled i] When Mag is in place and properly secured.
[page break]
[underlined] Cocking By Hand [/underlined]
On Cocking handle being pulled backwards, the CH catch is disengaged from the recess in body of the gun, and allows CH too [sic] be drawn to rear. CH. engages against rear of of [sic] the slot on left hand side of piston rod. The piston rod is thus drawn to rear carrying with it the Breech Block, till bent on piston rod is engaged by sear. During this movement of the piston rod, the rear sear [indecipherable word] the cocking handle must now be returned to Fire position, the gun is then ready to fire
[underlined] Forward Action [/underlined]
(a) When trigger is pressed the short arm forces trigger forward and compresses trigger spring. The forked for [sic] end of trigger rod being engaged against lower arms of sear rotates out its own axis pin compressing sear spring & withdrawing nose of sear bent on the underside of Piston Rod. Meanwhile as [missing words] move forward, sear
[page break]
is rotated under the action of its spring, the arms engage over step of sear. When nose of sear is disengaged from the bent of Piston Rod, Piston Rod is forced forward by compressed return springs carrying with it the BB.
(B) Feeding of Round in Magazine to chamber
As BB moves forward the Firing Pin engages against base of cartridge; under the influence of the bullet guide (which) guides bullet into chamber, then deflects base of cartridge down to face of BB where it is engaged by extracter [sic]. The final forward movement of BB forces cartridge fully home into chamber
[underlined] Action of Magazine [/underlined]
Insured [sic] each cartridge is clear of lips of mag remainder of cartridges in mag rear move round bodily by action of main spring acting on top plate until next round is positioned in mag lips ready for next feed movement. Piston Rod bears against
[page break]
[blank page]
[page break]
[drawing]
[page break]
[blank page]
[page break]
[blank page]
[page break]
[drawing] [calculations]
[page break]
[underlined] The Reflector Sight [/underlined]
The advantages of the reflector sight
A. Position of eye is not critical
B. No lining up of sight, in ring & head.
C. Both eyes should be kept open
D. Can be used against sun
E. Can be used at night
[underlined] Disadvantages [/underlined]
A. Electrical
B. fragile
C. Expensive
D. Hood partially obscures vision
E. Condensation of reflector glass.
[diagram and key]
[page break]
[underlined] Gravity Drop. [/underlined]
Gravity drop is the force of gravity acting on the bullet.
Bullet drop is always greatest at the horizontal round the aircraft
[diagram and calculations]
[page break]
[underlined] Tracer Sighting contd [/underlined]
1 Recognise & identify a/c
2 – Estimate range RS.
3 – When a/c is approx. 400 yds, position a/c in centre of sight and fire a short burst (sighter burst). Still keeping a/c in RS. note end of tracer in relation to RS.
4 – Allowances depend on type of tracer used.
[underlined] Using G1 [/underlined]
Position a/c on end point of trace & maintain this aim until a/c closes to range approx. 150 yds then fire point blank.
[underlined] Using G2 [/underlined]
This tracer extinguishes 1200 yds. End point unreliable. (If the end point of tracer is inside) ring fire point to blank at all ranges. If end point is outside ring sight position a/c 1/2 - 2/3 of radius of ring along the tracer. Maintain and same as G1.
[page break]
[underlined] Using G4 [/underlined]
This extinguishes at 600 yds, position a/c 1/2 along trace & finish as before.
[underlined] Advantages of Tracer Sighting [/underlined]
[circled 1] Sighting reduced to (wide) rule of thumb method.
[circled 2] No allowance has to be made for gravity drop, because sights are harmonized with gun. You see where bullets are going also proving the point.
[circled 3] Trace tells of deflection or if deflection shot is required, and indicates what allowance should be made. G1 & G4 give indication of amount of deflection required.
[circled 4] Attacker can see bullets and is disconcerted [inserted] perhaps?!!!! [/inserted]
[page break]
[underlined] Disadvantages of Tracer Sighting [/underlined]
Trace gives immpression [sic] target is being hit whether the amount of deflection is a little, correct, or too great.
There is a tendency to use trace by hose piping method.
At night it may dazzle gunner so target is obscured.
Owing to rapid reduction in the brilliance of the light source bullets appear to go more quickly & appear to be further away at any instant than they are, infact [sic].
The advantage of surprise is eliminated when 1st burst is fired.
[page break]
[blank page]
[page break]
[blank page]
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if below, pump [indecipherable word] to 4" extension.
3 – Start up EDP and run at max revs allowed. Operate turret slowly & seperately [sic] in all directions This will displace air from the system, valve box & VOM. This air will lodge itself under the spring loaded plunger of the recuperator. STOP ENGINE.
4 – Pump up recup [sic] to its fullest extent & continue pumping until the air has been displaced through the weep holes in the recup. Then completely fil [sic] reservoir.
5 – With rams fully contracted bleed system at rear sear release pipe lines until recuperator spindle extends 4". (Should rams be left fully extended recup spindle should extend 3" only). Do not add any more oil to reservoir as the required oil/air space is now completely adjusted.
6 – Replace & tighten filler cap.
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4 – When clean oil appears at inlet side of pump tighten union, continue pumping till clean oil appears at pressure union. Tighten union.
5 – Pump up recup. until spring loaded plunger is fully extended. Continue pumping to displace air trapped under plunger.
6 – With master valve depressed, work control valves so as to fill up unit and pipes
[underlined] Bleeding [/underlined]
1st Slacken off bleeder screws at top of rams bodies, with master valve depressed operate elevation valve for ram extension. Tighten bleed screws when clean appears
1 – Slacken off bleed screws at end of ram piston-rods with master valve depressed operate EV as for ram contraction, Tighten bleed screws when clean oil appears.
2 – Check recuperator spindle height and
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[diagram]
[underlined] Bleeding & Filling [/underlined]
[underlined] Filling [/underlined]
Obtain correct oil correctly filtered.
1 – [indecipherable word] that gun rams are fully closed.
2 – Slacken of [sic] union nuts of EDP.
3 – Remove Filter cap using gauze lined funnel fil [sic] recup reservoir, at the same time working the hand pump steadily.
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[underlined] The Frazer Nash Turret. [/underlined]
[underlined] The recuperator & its duty or rather duties [/underlined]
1 – To act as a chamber of every, varying capacities or volume.
2 – Maintain at all times at low pressure of 16-20 lbs on the inlet side of the pump when the engine is running, throughout the whole system, when the engine is not running.
3 – To provide a reserve supply of oil to make good slight actual loss.
4 – To provide a means of filling and topping up the closed circuit.
[diagram]
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[blank page]
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[underlined] The Hydrolic [sic] System, Circuit [/underlined]
[diagram]
[underlined] The electrical Circuit [/underlined]
[diagram]
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the top chamber through the open bleeder valve.
(8) At the end of stroke, top up sump.
(9) leave bleeder valve open, and pump for depression.
(10) Watch for ejected oil at bleeder valve when it appears tighten valve.
(11) Elevate and depress a few times.
(12) Top up sump.
(13) Elevate guns approx. 40°
(14) Slacken off connection of Hyd [sic] Motor
(15) Operate turret for rotation
(16) Watch for ejected oil.
(17) When oil is ejected reverse rotation. Again watch for oil. Tighten union
(18) [symbol] Operate Turret in all directions
(19) Top up sump and fill up filler cap.
It is important that the force or free & engage lever is kept engaged & the pump should never be used at more than 1/2 stroke.
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[underlined] The Boulton & Paul Turret [/underlined]
[underlined] Bleeding & Filling [/underlined]
Remember [inserted] that [/inserted] at commence operations pipe lines will be filled with air, every effort must be made to force the air out as oil is pumping or rather pumped, and so prevent the possibility of air cushions – Stop turret and put guns horizontal and proceed as follows
[circled 1] Fill up sump with clean oil
[circled 2] Slacken off connection at lower end of Hyd Pump or Ram.
[circled 3] Start turret and work for elevation, oil will be pumped toward lower end of ram forcing air before it to escape at the loosed connections
[circled 4] Watch for ejected oil when it appears tighten connections
[circled 5] Top up sump.
[circled 6] Open fully, the Bleeder valve.
[circled 7] Continue to pump for elevation the piston will move upwards forcing the air from
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[notebook back inner cover – partly wrapped]
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[notebook back outer cover – wrapped]
Collection
Citation
Taplin, JA, “John Taplin's Air Cadet Notes,” IBCC Digital Archive, accessed May 21, 2026, https://ibccdigitalarchive.lincoln.ac.uk/collections/document/44366.