Service notebook of Harold Gordon Cornell - 1917 - Part 16

Rigging - Theory of Flight

Drift of 3 types.

(1) Active Drift. (produced by lifting surfaces)

(2) Passive Drift (produced by all non lifting pistons)

(3) Skin Friction (due to bad taping, flabby fabric)

Lift / Drift Ratio expresses the efficiency of a machine.

(Effected by six strings.

(1) Velocity. (stream lining to get over part of passive drift)

(2) Incidence (∠ between  chord  & direction of an attack)

angle varies with wt to be carried, climbing velocity

ratio, thrust.

(3) Camber (to reduce drift on under side enables air to glide

off plane, top camber helps to stream line

the drift area at rear of plane.)

(4) Aspect Ratio: Proportion of span to chord

Diagram - see original document 

Higher ration gives better lift, because

more air is met.

(5) Stagger. Advantage Reduces interference

Interference takes place unless gap is

1 ½ times the chord.

Interference eliminated with Stagger = ⅓ gap.

 

Rigging - Theory of Flight

(6) Horizontal Equivalent

H.E. when machine is flying  
H.E. diagram - see original

level is not equal to length of plane, when

machine banks slightly, H.E. of one plane

increases & other decreases. & so tends to

right machine. Hence dihedral decreases efficiency

but increases stability.

Margin of Power Power of available over that necessary

to maintain horizontal flight

Margin of Lift Height a plane can attain in given time from

a given altitude (Decreases as machine reaches

higher altitudes)

Minimum Angle of Incidence Lowest angle at

which flight can be maintained.

Maximum Angle of Incidence Greater ∠ at which etc.

Optimum Angle of Incidence. Angle at which

Lift Drift ratio is highest

Best Climbing Angle approximately ½ way between

maximum & optimum.

 

- Theory of Flight -

Stability of 3 types Stable, unstable, neutral.

A body is stable when it tends to return to its

original position after being acted on by an outside

force; unstable when it tends to move further

& further from its original position; neutral stability

when it xx remains in any position in which it

is put.

On a flat surface centre of pressure moves

forward as incidence increases, in cambered surface

backward.

Landing by Night

Diagram - see original document

Flares as shown

also red lights

at extreme limits

of aerodrome 

Flares are buckets of

petrol and waste

 

 

- Theory of Flight -

Longditudinal dihedral is angle between tail

plane & main planes thus

Diagram - see original document

 

1.

Vickers Light Automatic Machine Gun

General Description

Calibre .303; recoil operated & water cooled.

Worked by two forces (1) force of explosion

                                    (2) action of fusee spring

Average rate of fire - 500 rounds per minute

Weight of gun 28½ lbs, and 32½ lbs. Weight increased

by 10 lbs when barrel casing, which holds 7½ pints water is filled.

Length of barrel 28 metres; Turn of rifting - left.

Number of turns in length of rifting - three

&   "       "   bands - five

Chamber pressure 19 tons per |_|     {applies with

Muzzle velocity, 2460 ft per sec.        { Mark VII

Rise of trajectory. 18" in 400 yds        { ammunition only

The gun is divided into two portions, non-recoiling

and recoiling:

Non Recoiling Portions consist of.

(1) Barrel casing

(2) Breach casing comprising left and right outside

plates, bottom plate, front and rear cover, & rear

cross pieces.

 

2.

Vickers Light Automatic Machine Gun

Recoiling Portions consist of:

Barrel inside plates, crank & lock: With these

may also be included - feed block. fusee spring & muzzle cup.

Mechanism.

The mechanism is divided into 16 different sequences.

(1) Action of recoil

(2) First action of feed block

(3)     "       rotation of crank

(4) Second  "    "    "

(5)    "    action of feed block

(6) Outside  "    "  lock

(7) Cocking of the  "

(8) Forward rotation of crank

(9)     "   movement of lock

(10) Closing of the breech

(11) Depression of rear

(12) Firing of the first shot.

(13) Continuous fire

(14) Cease fire

(15) Unload    (16) Clear gun.

 

 

3.

Vickers Light Automatic Machine Gun

1. Action of Recoil. When the cartridge in the chamber is

primed, the force of the explosion drives the recoiling

portions p back a distance of about one inch

giving the fusee spring its first extension. The

recoil is assisted by the gases striking the muzzle

cone & rebounding on to the muzzle cup.

2. First Action of the Feed Block As the recoiling portions move 

backward, the skid on the lower lever of the feed

block, which is engaged in the recess of the prolongation

of the left inside plate, draws the lower lever of feed

block from front to rear. The upper lever which

is attached to the lower lever & set at right angles

to it, moves from left to right, taking with it the slide

to which it is attached by a stud. The upper pawls

which are fixed to the slide move to the right &

engage behind the first cartridge in the belt, already

gripped by the bottom pawls.

First Rotation of Crank The recoil causes the tail

of the crank handle to roll on the roller thereby

rotating the crank, drawing back the lock & causing

4.

Vickers Light Automatic Machine Gun

the fusee chain shaft to wind itself round the fusee

thus further extending the fusee spring.

4. Second Rotation of Crank The continued rolling of

the crank handle against the roller, assisted ^by the

fusee spring, forces recoiling portions forward again

with the exception of the lock, which continues its

backward movement for a short distance before

joining in the forward movement.

5. Second Action of Feed Block The skid on the lower

lever being engaged in the recess of the prolongation

of the left inside plate, and the lower lever being set

at right angles to the top lever, moves the slide

and top pawls from right to left. The top pawls

carry with them a live (cartridge round) in the belt,

placing it in position against the cartridge & bullet

stops, ready to be gripped by the extractor when it

rises, at the same time the lower pawls are depressed

and rise behind the next cartridge in the belt, so

preventing the bolt from slipping back when the cartridge

is withdrawn from the feed block.

 

5.

Vickers Light Automatic Machine Gun

6. Outside Action of Lock When the lock comes back

a live round is taken from the feed block, the

cartridge being gripped between the upper & lower

projections of the gib, and an empty case from

the chamber. The horns of the extractor ride along

the skid cams until they are forced down by the

ramps on the underside of the rear-cover. The

live round which has been taken from the feed

block, is then opposite the chamber, and the empty

case from the chamber drops off or is ready to be ejected.

7. Cocking the Lock. The rotation of the crank

gives the side lever head & connecting rod a backward

and upward movement. The side lever head, engaging

bearing on the tail of the tumbler rotates it on its

axis and the head of the tumbler, being engaged in

the recess in the firing pin draws the firing pin to

the rear. The long arm of the lock-spring, which is

engaged behind the projection on the firing pin, is

compressed towards the short arm. The short arm

bearing in the nose of the trigger forces it over the bent

 

 

6.

Vickers Light Automatic Machine Gun

of the tumbler. The side lever head bearing still

further on the firing pin tail of the tumbler further

rotates it on its axis drawing the firing pin still

more to the rear, & further compresses the lock-spring

until the bend in the firing pin becomes engaged

with the bent on the rear, activated by the rear spring

The lock is now fully cocked.

8. Forward Rotation of Crank

When the force of the explosion is expended the action

of the fusee spring comes into play, unwinding the

fusee chain from the fusee, so rotating the crank

and causing the lock to go forward again.

9 Forward movement of lock.

When the lock goes forward, the flanges ride

along the lock guides and a live round from the

feed block is placed in the chamber. The side

levers bearing bearing on the extractor levers, cause

the extractor to rise. When the extractor rises,

the upper projector on the gib rides over the base

of the cartridge in the chamber feed-block, the