Cutaway model of a 7,3 cm RSprgr (Rocket High explosive shell) for the Föhn rocket launcher. In 1943 Germany started development of flak rockets beside the existing flak guns. The advantages were; low cost for building launchers and ammunition, the disadvantages: less range (or in this case ceiling) and less accuracy. The first to appear was the Föhn gerät, a 35 frame launcher with fast elevating and transverse gears. All 35 rockets could be fired simultaniously. The rocket was meant for barage fire against low flying aircraft.
The rocket is made of two parts, a rocket motor and a warhead. The rocket motor consists of a pipe with a ring flange on the top side . This ring shaped flange receives a flange that forms a plug in top of the motor, holding the self destruct device. The pipe is externally threaded for an inch on the outside on both top and bottom. The top thread receives the cast iron warhead, the lower thread recives the bottom plug, which holds the central firing cap as well as two rows of seven ventiri. The outer row is angled to cause the projectile to spin, the inner row are straight venturi.The propellant exists of a 450 grams Dyglykol stick with a central perforation and eight outer perforations. Ribs on the outside of the stick enable the flame of the igniter charge to fully surround the stick. On top of this stick is a sheet metal spacer , holding the igniter charge. The igniter charge and the firing cap are connected by a quickmatch. Below the propellant stick is a 3mm thick pressed black powder ring that prevents the venturi holes from being blocked. The warhead consists of an ogive shaped cast iron body, threaded internaly in the nose to receive the RAZ51 (RaketenAnschlagZünder, Direct action rocket fuze)and threaded internaly in the bottom to receive the motor. The RAZ 51 is an aluminium fuze where two centrifugal segments are thrown outward , thereby releasing the firing pin . At launch, a steel ring is forced into a groove in top of these two segments by the acceleration , thereby preventing the segments to move outward until the acceleration has decreased , so the rocket is armed on a safe distance from the launcher. At impact , the firing pin is driven into a duplex detonator , exploding the warhead. If no target is hit , the self destruct element that has been ignited by the igniter charge of the motor, will burn up and send a flame into the duplex detonator on top of the delay element, thus exploding the shell. It is not known if an earoplane was ever actually shot down with a Föhn gerat, but it was extensively used in fixed positions and mounted on verhicles, both in the role of light artillery.
Weight: 2,74 Kg.
Length: 282 mm.
Diameter: 73mm.
Three type of explosive charge were used; Fp02 (cast TNT), Fp60/40 (60% TNT & 40% ammoniumnitrate) or H5 ( Hexogen with 5% wax). The weight of all of these charges was 280 grams.
The Self destruct device and both detonators are replica's.
If you put your printer settings the right way, you can make a 1:1 scale print on a A4 paper,
The rocket is made of two parts, a rocket motor and a warhead. The rocket motor consists of a pipe with a ring flange on the top side . This ring shaped flange receives a flange that forms a plug in top of the motor, holding the self destruct device. The pipe is externally threaded for an inch on the outside on both top and bottom. The top thread receives the cast iron warhead, the lower thread recives the bottom plug, which holds the central firing cap as well as two rows of seven ventiri. The outer row is angled to cause the projectile to spin, the inner row are straight venturi.The propellant exists of a 450 grams Dyglykol stick with a central perforation and eight outer perforations. Ribs on the outside of the stick enable the flame of the igniter charge to fully surround the stick. On top of this stick is a sheet metal spacer , holding the igniter charge. The igniter charge and the firing cap are connected by a quickmatch. Below the propellant stick is a 3mm thick pressed black powder ring that prevents the venturi holes from being blocked. The warhead consists of an ogive shaped cast iron body, threaded internaly in the nose to receive the RAZ51 (RaketenAnschlagZünder, Direct action rocket fuze)and threaded internaly in the bottom to receive the motor. The RAZ 51 is an aluminium fuze where two centrifugal segments are thrown outward , thereby releasing the firing pin . At launch, a steel ring is forced into a groove in top of these two segments by the acceleration , thereby preventing the segments to move outward until the acceleration has decreased , so the rocket is armed on a safe distance from the launcher. At impact , the firing pin is driven into a duplex detonator , exploding the warhead. If no target is hit , the self destruct element that has been ignited by the igniter charge of the motor, will burn up and send a flame into the duplex detonator on top of the delay element, thus exploding the shell. It is not known if an earoplane was ever actually shot down with a Föhn gerat, but it was extensively used in fixed positions and mounted on verhicles, both in the role of light artillery.
Weight: 2,74 Kg.
Length: 282 mm.
Diameter: 73mm.
Three type of explosive charge were used; Fp02 (cast TNT), Fp60/40 (60% TNT & 40% ammoniumnitrate) or H5 ( Hexogen with 5% wax). The weight of all of these charges was 280 grams.
The Self destruct device and both detonators are replica's.
If you put your printer settings the right way, you can make a 1:1 scale print on a A4 paper,
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