To quote from 'Field rocket equipment of the German army 1939-1945 T.J. Gandar':
The 8 cm Rocket
The sharp division of status and establishment between the regular Wehrmacht and units of the Waffern SS even went down to equipment and weapon level. Thus it is not surprising to discover that although the SS units also used the standard field rocket equipments, they developed and used a different type of rocket for issue to their formations alone. This rocket was the 8 cm Raketensprenggranate, developed from a projectile originally intended for aircraft use, and which differed from most of the larger field rockets in being fin stabilised instead of spin-stabilised. it has been suggested that this form of rocket was adopted after experience under bombardment from Russian 'Katyusha' projectors and the resemblance between the 8 cm rocket and its Russian Counterparts was close.
Actually, the diameter of the rocket was 78 mm, and the overall length was 27.7 inches (703 mm). Weight was 15 lb 3 oz. At the rear, four fins raised the diameter to 7.875 inches (200 mm). The propellant used was six cordite sticks which were electrically primed and ignited by two gunpowder discs. Exhaust gases vented through a single 20 mm base venturi. Motor weight was 10 lb (4.54 kg).
The warhead was formed of three perforated pellets of pressed flake TNT weighing 1 lb 51/2 oz (610 gms). Arming of the warhead was effected partially by the burning propellant which melted a soft metal disc and allowed the detonator to approch a centrifugally-released stricker, ready for the nose impact fuse to set off the warhead. Maximum range of the 8 cm rocket was 5796 yards (5300 m) with a velocity of 950 f/sec. A smoke carrying version was also used.
The main launchers for this rocket were the multiple projector known as the 8 cm R-Veilfachwerfer which could fire up to 45 rockets in one salvo, and the single Mantlerohr. Both launchers were of the rail variety and resembled current Russian equipment. In both types the rocket lay on rails supported by four metal studs, two on each side of the rocket body.
Quatermass