Monday 19 December 2016

British Explosive Ordnance - Semi-Armor Piercing, Armor Piercing, and Deep Penetration Bombs








British Explosive Ordnance





 Semi-Armor Piercing and Armor Piercing Bombs Introduction



There are two British SAP bombs in present service use.  They are designed for penetration of resistant targets, such as reinforced concrete or medium armored targets, where penetration is required before the bomb detonates.

Only one AP bomb, the 2000lb, is used by the British.  It is used for attacks against heavily armored targets, such as capital ships, and is so constructed and fuzed that the bomb does not break up on impact.  Detonation does not occur until after the target is penetrated.  A 450lb AP bomb was used early in the war, constructed along the same lines as the 2000lb, but it is now obsolete.

Both the AP and SAP bombs are fuzed in the tail only.  Earlier marks were designed to receive a tail fuze, but later marks are fitted for pistol/detonator combination.  In later marks, the pistol used for fuzing is supplied in position in the bomb, without detonators, where it acts as a tail transit plug.

SAP bombs are dark green overall, with a white band on the nose just before a red band.  The actual construction is similar to the GP bombs, but the case is thicker, and they are even more streamlined.  They are normally filled with TNT, and have a loading factor of about 20 percent.  Mks I, II, III, and IV have tails secured by a fuze locking ring which is threaded left-handed, while the Mk V has a clip-on tail.

AP bombs are dark green in color.  The nose is painted light green to the point of widest diameter.  Two white bands, separated by a red band, are painted around the nose.  The bombs are of one-piece construction, and are filled with shellite, which consists mainly of picric acid and is very insensitive.  The loading factor is about 10 percent.





SAP 250lb Mks II and III (Obsolete), and Mks IIC, IIIC, and V (Service)


Overall length: 49 inches
Body length: 31.5 inches
Body diameter: 9.2 inches
Wall thickness: 0.91 to 0.99 inches at maximum  diameter and 0.61 to 0.69 inches at minimum thickness beginning 16.8 inches abaft nose.

Tail length: No.10 Mk I and No.5 Mk I - 18 inches
Tail width: 9.2 inches
Total weight: 245 pounds
Charge/Weight ratio: 17%

Fuzing:
-Mks II-IV: Tail Fuze No.30
-Mk V: Tail Pistols No.28 or No.30

Tail No:
-Mks II and III: No.1 Mk I
-Mk V: No.10 Mk I

Color and markings:  Dark green overall
1/2 inch white band 3 inches from nose,
1/2 inch red band 3 and 1/2 inches from nose,
1 inch light green band 6.5 inches from nose.

  
Body Construction: The Mk V body is forged steel with a pointed nose and an open base threaded internally to receive the exploder container, which is cemented in position.  The base of the body is threaded externally to receive a tail adapter, which is in the form of a coned ring with four equi-spaced slots to receive the spring clips of the tail.  Earlier marks were similar to the Mk V, with slight variations in the tail adapter.


Tail Construction: The Tail No.10 Mk I has a tail cone with a cylindrical strut attached by four fins.  It is attached to the bomb body by four spring clips.  The arming spindle engages the fork in the tail pistol.  The Tail No.1 Mk I, used on Bombs Mk II and III has no spring clips, while the Tail No.3 Mk I used on Bombs Mk IIC, Mk IIIC, does have spring clips.


Suspension: A single suspension lug is secured to the body by four screws.
  

Explosive Components:
Exploders: CE pellets in Mks II-IV, and HE in the Mk V.

Filling:
-Mk V: 40.5 pounds TNT/Beeswax
-Mks II-IV: 41.5 pounds TNT


Remarks: The Tail Fuze No.30 has left-hand threads on the securing ring.  Use of the Tail Pistol No.37 is unlikely. 

Tail fins are usually painted red when the Time Pistol No.37 is used.

Any mark may be found fitted with a copper driving band for proof firing from the BL 9.2 inch Howitzer.









SAP 500lb Mks II-III (Obsolete), and Mks IIC, IIIC, and V (Service)
   

Overall length: 62 inches
Body length: 41.8 inches
Body diameter: 11.5 inches
Wall thickness: 1.22 to 1.32 inches at maximum  diameter and 0.82 to 0.92 inches at minimum thickness beginning 23 inches abaft nose.

Tail length:
-No.6 Mks I: 21 inches
-No.11 Mk I: 20.4 inches
-No.27 Mk I and II: 9.24 inches

Tail width: 11.5 inches
Total weight: 490 pounds
Charge/Weight ratio: 18%

Fuzing:
-Mks II-IV: Tail Fuze No.30
-Mk V: Tail Pistols No.28 or No.30

Tail No:
-Mks II and III: No.1 Mk I
-Mks IIC and IIIC: No.4 Mk I
-Mk V: No.11 Mk I, or No.27 Mk I

Color and markings:  Dark green overall
1/2 inch white band 3 inches from nose,
1/2 inch red band 8 and 1/2 inches from nose,
1 inch light green band 8 inches from nose.

  
Body Construction: The Mk V body is forged steel with a pointed nose and an open base, threaded internally to receive the exploder container, which is cemented in position.  The base of the body is threaded externally to receive the tail adapter, which is in the form of a coned ring with four equi-spaced slots to receive the spring clips of the tail.  Earlier marks were similar to the Mk V, with slight variations in the tail adapter.


Tail Construction: The Tails No.27 Mks I and II are the short-type tail unit with arming vanes protruding beyond the strut and fins.  The Tail Assembly No.11 Mk I consists of a tail cone with a cylindrical strut attached by means of four fins.  It is attached to the bomb body by four spring clips.  The arming spindle engages the fork in the tail pistol.  The Tail No.1 Mk I used on Bombs Mk II and Mk III has no spring clips, while the No.4 Mk I tail used on Bombs Mk IIC and Mk IIIC does have spring clips.


Suspension: A single suspension lug is secured to the body by four screws.
  

Explosive Components:
Exploders: CE and TNT in Mks II-IV; CE only in Mk V.  There is no separate layer of TNT around the exploder as in the 250lb SAP Mk V.

Filling:
-Mks II-IV: 90 pounds TNT
-Mk V: 89 pounds TNT


Remarks: The Tail Fuze No.30 has left-hand threads on the securing ring.

Use of the Tail Pistol No.37 is unlikely, but if used, tail fins are usually painted red.

The Bomb Mk I is very old and will not be found.  The Mk IV bomb was manufactured, but never filled.







AP 2000lb Mks I, II, III, and IV (Service)
   

Overall length: 113 inches
Body length: 80 inches
Body diameter: 13.5 inches
 Wall thickness: 2.4 inches (approx.)
 Tail length: 35.5 inches
 Tail width: 13.5 inches
Total weight: 1934 pounds
Charge/Weight ratio: 9%

Fuzing:
-Mks I, II, and III: Tail Fuze No.37
-Mk IV: Tail Pistol No.30

Tail No:
-Mk I: No.1 Mk I
-Mks II and III: No.10 Mk I
-Mk IV: No.47 Mk I

Color and markings:  Dark green overall, with light green nose
Three 1/2 inch bands, white, red, and white respectively, painted 4 inches to 5 and 1/2 inches from tip of nose.

  
Body Construction: The Bomb Mk I has a forged steel body with a solid nose approximately 1.9 feet long and a slight taper from the maximum diameter to the tail.  The base is threaded externally to take a tail adapter, and internally to take a base adapter, which receives the exploder container.  The fuze is locked in position by a fuze securing ring.  The Mks II and III are similar to the Mk I, except for the tail adapter, which has four equi-spaced holes threaded for attachment of the tail.  The Mk IV is modified to take a Tail Pistol No.30.


Tail Construction: The Tail No. 1 Mk I is of aluminum alloy, consisting of a cylindrical strut attached to the tail cone by four vanes.  It fits over the tail adapter and is secured by six screws.  The Tail No.15 Mk I is similar to the No.1 Mk I, but is made of steel.  It has a strengthening ring two inches from the base, and is secured to the tail adapter by four wing bolts.  The Tail No.47 Mk I consist of a cylindrical strut secured to the tail cone by four fins which are riveted on.  A reach rod extends through the tail cone, and is supported by a spider.


Suspension: The bomb is suspended from the plane by two suspension bands.
  

Explosive Components:
Exploders: CE issued in position in exploder container.
Filling: 166 Shellite, with a composition pad in the forward end of the cavity, sealed aft with washers and cement.  Shellite is a very insensitive explosive consisting of 70% picric acid and 30% dinitrophenol.




Deep Penetration Bombs Introduction

These bombs were designed for special operational uses to give deep penetration of the earth and to produce heavy shock waves as a result of the explosion of their main charge.  They have a charge/weight ratio of about 45%, and are not intended for use as armor- or concrete-piercing bombs.

The two sizes of bombs are identical in all respects, the 22000 pound DP being merely an enlarged version of the 12000 pound DP.  A rather unusual feature of these bombs is the use of a cowl between the bomb body and the tail assembly to enhance their streamlining.  Both DP bombs are tail fuzed only, each bomb using three Tail Pistols No.58 located 120 degrees apart in the base plate.

These bombs have been adapted by the US for service use after slight modifications in the method of construction.


DP 12,000lb Mk I "Tallboy" (Service)

Overall length: 21 feet
Body length: 10 feet, 4 inches
Body diameter: 3 feet, 2 inches
Wall thickness:
-Near tail: 1.25 inches
-Near nose: 4.1 inches

Tail length: 10 feet, 8 inches

Tail width: 3 feet, 6 inches (across fins)
Total weight: 11,885 pounds
Charge/Weight ratio: 45% (approx.)

Fuzing: Mk III - Three Tail Pistols No.58 Mk I

Tail No: No.78 Mk I
  

Color and markings: Green overall, Red band near nose


Body Construction: The bomb body is manufactured of cast steel, with a solid nose plug, and with three exploders fitted 120 degrees apart in the base plate.  The bombs are issued with exploders inserted, and the exploder tubes are sealed with shipping plugs.

The tail is attached to the after end of the bomb body by 12 studs.  A cylindrical metal cowling, placed between the bomb body and the tail cone, enhances the streamlining of the bomb.

The bomb body contains an explosive filling of Torpex with a one-inch layer of TNT topping added to the after end.  Four inches of wood-meal/wax composition is then added, and the filling sealed with a 1/2 inch plyboard washer.  The three exploders pass through holes in this washer and are held in place by a heavy base plate, which is secured by bolts to the bomb body.


Tail Construction: The special tail unit, No.78 Mk I, is constructed of light alloy and consists of a cone to which are attached four fins of streamlined cross-section.  The fins are set at an angle of 5 degrees to the axis of the tail cone, giving a slight right-hand spin to the bomb as it falls.  The tail fits over twelve 7/16 inch studs fitted into the bomb body, and is securely fastened to the studs by Simmonds nuts.  Three hand-holes in the tail cone give ready access to the three tail pistols.
 
Suspension: The bomb is suspended in the plane by twin suspension links.  Each link is coupled beneath the bomb by a special Vickers release clip, capable of either electrical or manual operation.

In addition to the suspension links, the bomb is positioned in the plane by a standard crutching system.
  

Explosive Components:
Exploders:
-Primary: 2 ring and 2 solid CE pellets; 4 solid RDX/Beeswax pellets
-Secondary: 2 ring and 2 solid large RDX/Beeswax pellets (placed in a special exploder tube into which the standard exploder container fits)


Main Filling: Approximately 5,200 pounds Torpex surmounted by a 1-inch topping of TNT.


Remarks: This bomb is designed for special operation uses, and its employment will be restricted to certain specified bomb commands.  The initials "DP" signify its deep penetration characteristics, although the bomb is not designed for armor or concrete piercing.  Rather, it is intended to produce heavy shock waves as a result of the explosion of its heavy main charge deep within the earth.

The bomb is carried on specially adapted Lancaster aircraft.  The striking velocity of the bomb, when released at an altitude of 18000 feet, and an air speed of 200 mph, is stated at 1,097 ft/sec at which speed it has developed a rotational velocity of 300 rpm.

The filling and exploder system of this bomb is identical to that of the 22000 pound DP Bomb, "Grand Slam".  The two bombs are identical in all respects, the 22000 pound DP being merely an enlarged version of the 12000 pound DP Bomb.










DP 22,000lb Mk I, "Grand Slam" (Service)

Overall length: 25 feet, 6 inches
Body length: 12 feet, 6 inches
Body diameter: 3 feet, 10 inches
Wall thickness:
-Near tail: 1.75 inches
-Near nose: 7.75 inches

Tail length: 13 feet, 4 inches

Tail width: 4 feet, 4 inches (across fins)
Total weight: 22,400 pounds
Charge/Weight ratio: 42% (approx.)

Fuzing: Mk III - Three Tail Pistols No.58 Mk I

Tail No: No.82 Mk I
  

Color and markings: Green overall, Red band near nose


Body Construction: The bomb body is manufactured of cast steel, with a solid nose plug and with three exploders fitted 120 degrees apart in the base plate.  The bomb bodies are issued with exploders inserted, and the exploder tubes are sealed with shipping plugs.

The tail is attached to the after end of the bomb body by 12 studs.  A cylindrical metal cowling, placed between the bomb body and the tail cone, enhances the streamlining of the bomb.

The bomb contains an explosive filling of Torpex, with a one-inch layer of TNT topping added to the after end.  Four inches of woodmeal/wax composition is then added, and the filling sealed with a 1/2 inch plyboard washer.  The three exploders pass through holes in this washer and are held in place by a heavy base plate, which is secured by bolts to the bomb body.


Tail Construction: The special tail unit, No.82 Mk I, is constructed of light alloy and consists of a cone to which are attached four fins of streamlined cross-section.  The fins are set at an angle of 5 degrees to the axis of the tail cone, giving a right-hand spin to the bomb as it falls.  The tail fits over twelve 7/16 inch studs fitted into the bomb body, and is securely fastened to the studs by Simmonds nuts.  Three hand-holes in the tail cone give ready access to the three tail pistols.
 
Suspension: The bomb is suspended in the plane by twin suspension links.  Each link is coupled beneath the bomb by a special Vickers release clip, capable of either electrical or manual operation.

In addition to the suspension links, the bomb is positioned in the plane by a standard crutching system.
  

Explosive Components:
Exploders:
-Primary: 2 ring and 2 solid CE pellets; 4 solid RDX/Beeswax pellets
-Secondary: 2 ring and 2 solid large RDX/Beeswax pellets (placed in a special exploder tube into which the standard exploder container fits)

Main Filling: Approximately 9,200 pounds Torpex surmounted by a 1-inch topping of TNT.


Remarks: This bomb is designed for special operation uses, and its employment will be restricted to certain specified bomb commands.  The initials "DP" signify its deep penetration characteristics, although the bomb is not designed for armor or concrete piercing.  Rather, it is intended to produce heavy shock waves as a result of the explosion of its heavy main charge deep within the earth.

The bomb is carried on specially adapted Lancaster aircraft.  The striking velocity of the bomb, when released at an altitude of 16000 feet, and an air speed of 200 mph, is stated at 1,097 ft/sec at which speed it has developed a rotational velocity of 60 rpm.

The general arrangement of this bomb is identical to that of the 12000 pound DP Bomb "Tallboy".  The two bombs are identical in all respects, the 22000 DP being merely an enlarged version of the 12000 DP Bomb.

Grand Slam bombs made in the US differ somewhat in body construction from those made in Britain.  The body is built up of five sections welded together.  The solid nose and the base sections are made of forged steel, while the three center sections are made of rolled plate, longitudinally welded, taper-bored internally, and then set in a die to form the external contours.





Next Time:  Anti-Submarine and Buoyancy Bombs, and Aircraft Depth Charges

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