This equipment, known as the “Bumble Bee,” is composed of the 15 cm heavy field howitzer mounted on a modified Pz. Kw. IV tank chassis. It should not be confused with the 10.5 cm l.F.H. 18/2 (“Wasp”), which is the 10.5 cm light field howitzer mounted on the chassis of a Pz. Kw. II tank. The road performance of the “Bee” will approximate that of the Pz. Kw. IV tank.
In the construction of this vehicle the following modifications were made to the hull of the Pz. Kw. IV tank. The turret top plate mounting the turret traversing ring, the front vertical plate, and the rear partition separating the engine from the fighting compartment have been removed. The engine, cooling-fan assembly and exhaust pipes have been moved forward up to the gear box. A partition has been built across the width of the hull dividing the driver and assistant driver from the fighting compartment. A steel plate separates the engine from the fighting compartment. In place of the driver’s entrance hatches a cover similar to a cupola, with lid and shutter type vision, is provided.
The superstructure is in the form of a sloping four-sided shield 10 mm (.39 inch) thick. The front of the shield provides a bulging slot for the traverse and elevation of the gun while the rear plate is fitted with a hinged door.
The gun is mounted well back on the top of the engine cover plate by means of angle iron and steel brackets so that its muzzle projects almost flush with the nose of the hull. It retains its original buffer, recuperator and compensator, and elevating and traversing gears. Its overall length including muzzle brake, with which it must be fitted when firing charge 8, is 17 feet, 4 1/4 inches. The muzzle velocities of this piece are: Charge 6, 1,020 f.s.; Charge 7, 1,375 f.s.; Charge 8, 1,965 f.s. The maximum ranges are: Charge 6, 10,550 yards; Charge 7, 12,140 yards; Charge 8, 14,380 yards. Its elevation is 0°-39°; traverse each side 16°.
SPECIFICATIONS
| Weight | 28 tons | |
| Length | 20 ft., 4 1/2 ins. | |
| Width | 9 ft., 4 1/2 ins. | |
| Height | 9 ft., 4 ins. | |
| Ground clearance | 15 ins. | |
| Tread centers | 7 ft., 11 ins. | |
| Ground contact | 11 ft., 6 ins. | |
| Width of track | 15 ins. | |
| Pitch of track | 4 3/4 ins. | |
| Track links | 98 | |
| Fording depth | 3 ft. | |
| Theoretical radius of action: | ||
| Roads | 96 miles | |
| Cross-country | 62 miles | |
| Speed: | ||
| Road | 25 m.p.h. | |
| Cross-country | 12 m.p.h. | |
| Armor: | ||
| Front plate | 50 mm | |
| Sides | 30 mm | |
| Shield | 10 mm | |
| Armament | 15 cm s.F.H. 18/1 | |
| Ammunition | ||
| Engine | Maybach HL 120 TRKM, 320 hp. | |
| Transmission | Synchromesh—6 speeds forward, 1 reverse | |
| Steering | Epicyclic, clutch brake | |
| Crew | 5 |
German: p. 35