German Explosives
SBe Concrete Bomb (50kg AI, AII, C, CII, D, E)
AI
Overall length: 42.5 inchesBody Length: 35.6 inches
Body Diameter: 7.9 inches
Wall thickness: 0.9 inches
Tail Length: 16 inches
Tail Width: 11 inches
AII
Overall length: 42.9 inchesBody Diameter: 7.9 inches
C
Overall length: 43.1 inchesBody Length: 28 inches
Body Diameter: 7.9 inches
Wall thickness: 1.6 inches
Tail Length: 16.1 inches
Tail Width: 11 inches
CII
Overall length: 42.7 inchesBody Length: 28.6 inches
Body Diameter: 7.9 inches
Wall thickness: 1.5 inches
Tail Length: 16.1 inches
Tail Width: 11 inches
D
Overall length: 43.1 inchesBody Length: 28.7 inches
Body Diameter: 7.9 inches
Wall thickness: 2 inches
Tail Length: 16.1 inches
Tail Width: 11 inches
E
Overall length: 43.1 inchesBody Length: 28.7 inches
Body Diameter: 7.9 inches
Wall thickness: 1.5 inches
Tail Length: 16.1 inches
Tail Width: 11 inches
Filling: In earliest specimens, TNT. In all later specimens a naphthalene explosive mixture. This latter is a lower performance explosive, used perhaps for better fragmentation.
Total Weight: 49 to 52 kilograms
Color: Bright green overall
Construction: The concrete walls in all these models are loaded with small fragments of scrap metal. The explosive filling of the model A1 is surrounded by a thin sheet metal container which acts as a former for the concrete. The fragmentation effect of this bomb was apparently unsatisfactory, owing to excessive weight of explosive causing pulverization of the concrete. An attempt was made to improve it in Model C by reducing the weight of the explosive and increasing the thickness of concrete while still retaining the metal explosive container. A further modification along these lines was made in Model D, but it seems that the quantity of explosive had been reduced to too low a limit, and in Model E the weight of is increased in amount to be the same as Model C. The metal explosive container, however, has been dispensed with, and the concrete has been precast on a gridded steel rod framework. The steel framework is welded to a cast steel plug at the nose and a cast steel ring at the tail. The tails are of sheet steel. Early models had the tail set in concrete. Later models have a detachable tail.
Suspension: Vertical or horizontal suspension is used.
SBe 250kg Concrete Bomb
Body Diameter: 14 and 5/8 inches
Wall Thickness: 2 and 1/8 inches
Tail Length: 24 and 13/16 inches
Tail Width: 20 inches
Filling: Ammonium Nitrate with a small percentage of wood meal and aluminum. There is also a column of TNT pellets.
Weight of filling: 46 kilograms
Total weight: 250 kilograms
Charge/Weight ratio: 18%
Color: Blue green overall. Stenciled in black between trunnion band and fuze pocket.
Construction: The bomb body consists of a 1/8 inch metal explosive container. Surrounding the container is a 2-inch concrete apron with scrap steel imbedded throughout. A single transverse fuze pocket is used. A metal piece 3/16-inch thick of saucer shape, is the nose piece for the bomb.
The tail is sheet steel with four single braces.
Suspension: Horizontal. The lug is attached to the trunnion band which is removable.
SA 4,000kg
Body Length: 138 and 1/2 inches
Body Diameter: 37 and 1/2 inches
Wall Thickness: 1/8 inches
Filling: Matrix 50/50 amatol biscuits; aluminum/wax/RDX
Total Weight: 9,000 pounds (approx.)
Color: Fawn colored overall, sections are marked I, II, III, IV, and V. SA 4000 is painted in large black letters on the body. The letter V plus serial number of bomb is also present. The three specimens examined were 2, 3, and 7.
Construction: The bomb is made in five sections. The central section is 2 feet 4 and 3/4 inches long and remaining sections are 1 foot 10 and 1/4 inches long. Sections are cylindrical in shape and of sheet steel construction.
Each section has ends closed by a circular steel plate in which six holes are drilled and six steel tubes welded into position. When the five sections are assembled, six tie rods are passed through the steel tubes and secured at the extreme ends of the bomb by a washer and two nuts.
A central exploder tube is formed in each section in the same manner as the connecting tubes. Twenty-four picric acid pellets are stowed in the exploder tube of the central section and 18 pellets in each of the other exploder tubes. Exploder tubes are closed at each end by a cardboard disc held in position by a threaded washer.
A circular felt pad is placed between each section when the bomb is assembled. Three filling holes are provided in each section.
The nose fairing consists of a truncated conical section to which is welded a convex section; an internally threaded collar is welded to the convex section. A steel tube 3 feet 1 and 1/4 inches long is screwed into this collar. Three similar collars at an angle of 120 degree to each other are positioned off center on the convex section. Three steel tubes 9 and 1/8 inches long are screwed into these collars. The truncated conical section of the nose fairing is recessed at eight points to accommodate bolts which secure fairing to the bomb.
The ends of the long and three small tubes are fitted with steel closing plugs. A transverse fuze pocket is located in the central section. Fuze pocket appears to terminate at the central exploder tube.
No fuze has been found with the bomb but the threaded holes in the steel closing plugs accept the nose switch of the (55) A fuze. Also, there are slots in the truncated conical section of the nose that may be for electric cable leads. Locating ring attached to each bomb is of normal type and not of slotted type used with (55) A fuze.
Eight bolts which screw into the external plate of the after section appear to be for attachment of a tail unit, but no tail unit was found.
Suspension: The central section is fitted with a suspension lug. Lug being capable of limited lateral rotation. Section is also recessed and threaded at sides for fitting of trunnions.
BT (Bomben Torpedo)
General: The aircraft torpedo is an expensive, complicated weapon. The proportion of explosive weigh is low. Mass production is lengthy and expensive. In addition, present day performance of torpedo engines limit the speed and range of the projectile. Both of these items are essentials for accuracy and safety from anti-aircraft fire.
A relatively simple weapon would result were the torpedo engine and the control gear omitted. If this simplified weapon were launched so that the greater portion of the distance to the target was covered through the air, as with an ordinary bomb, the initial speed of the launch would be retained over nearly all the range. The projectile would enter the water just short of the target and carry on in the direction of its flight in air by reason of its momentum in the same was as does a torpedo. To prevent it from going too deep before detonation, a relatively flat angle of entry into the water is necessary.
Such a weapon was developed in Germany during the closing months of the war, and it was called the Bomben Torpedo. It combines the characteristics of the bomb to travel a long distance in a short time interval with the characteristics of a torpedo in that underwater travel eliminates range errors.
Details: The BT was developed in four sizes: 200kg, 400kg, 700kg, and the 1400kg. They all incorporated the same general shape and construction, and were entirely of steel. They were constructed in three pieces; the warhead (two sections) and the tail section. The forward section of the warhead was in the shape of a truncated cone, and the after section of the warhead was cylindrical. The transverse fuze pocket was located in the cylindrical section just aft the point where the two sections were welded together. The suspension lug T-type, was secured to the warhead just forward of this weld at the center of gravity.
Tail Section: The tail section was also in the shape of a truncated cone. There were three very large fins placed 120 degree apart at the after end of the section. This type of tail provided excellent stability for the bomb while it was in the air. The tail section was secured to the after section of the warhead in such a manner that when the missile struck the water, it was jettisoned.
Early in the experiments, a BT 1000 was worked on and this missile had a rocket motor inside the tail section. This idea was soon dropped as it proved impractical for the missile.
Underwater Behavior: The bomb must in no event ricochet off the water, not even in flat angles of entry, but must continue without deviation of its path of entry.
It is known that with ogival noses, as seen in the illustration of the BT 1400, a bomb will ricochet off the water when it strikes at a flat angle. By using a flat nose, as seen in the illustration of the BT 700, or better yet by using a spoiler plate, this ricochet at flat angles is definitely avoided. The front surface of the spoiler plate is made in the form of a section of a sphere of radius, equivalent to the distance between the surface of the spoiler plate and the bomb's center of gravity. As the flow of force is practically perpendicular to the upper surface of the body when it is awash, the resulting flow of force must go through the center of gravity and thus it causes no turning moment.
A spoiler plate with the same diameter as the bomb, however, has a high water drag. The ideal situation is to have the size of the plate less than the greatest caliber of the bomb body and so shaped that only the spoiler plate and no other part strikes the surface of the water at flat angles of entry.
Next Time: Paravane Bomb, and Incendiary, Smoke, and Practice Bombs (Part 1)
Source: German Explosive Ordnance Vol. 1: Bombs, Rockets, Grenades, Mines, Fuzes & Igniters
