German Explosives
Great Enzian
Description
The Enzian was conceived as a ground to air flak weapon. Its secondary purpose was that of an air-to-air weapon. Models E-1, E-2, and E-3 were the test and experimental articles. All flight tests were carried out with the E-1. The E-4 was the production design using an improved rocket motor, designed by Dr. Conrad instead of the Walter biliquid used int he earlier designs. As the foregoing is the only major difference in the four models, they will be discussed as one: however, there exists another type, E-5, which being a basically different type will be covered in a separate report to avoid confusion.
The E-4 is a flying wing design of striking similarity to the Me-163. Its total weight is 1,800 kg which includes the weight, 320 kg of the four assisted take-off units. The warhead's weight is 500 kg. The airplane is constructed of wood, having an overall length and span of four meters. It attained its velocity of 300 m/sec with a main thrust unit delivering 2,000 kilograms initially decreasing to 1,000 kilograms during the flight. Duration of power was 72 seconds, resulting in a vertical range of 16,000 meters and a horizontal range of 25,000 meters.
The four assisted take-off units deliver a combined thrust of 6,000 kilograms for 4 seconds, giving the missile which attains an end speed of 24 m/sec and an acceleration of 3.6 g from a launching ramp 6.8 meters in length. The assisted take-off units are jettisoned after 5 seconds.
Although it was anticipated that E-4 would be used as an air-to-air weapon with slight modification, principally reduced fuel load, all experimental flight testing had been done from ground to air. A standard 88 mm gun carriage was adapted for use as a launching platform by the simple addition of two iron rails 6.8 meters long. A traverse of 360 degrees and a vertical firing arc from 0 to 85 degrees were obtained. Air launching of the device was routine; i.e., dropping free from underneath the parent aircraft flying in the direction of the target.
The speed on leaving the launching rails is 24 m/sec; to avoid the possibility of stall no control is applied until the flying speed has reached approximately 55 m/sec. For practical purposes an elapsed time of 5 seconds is allowed between the triggering of the launching mechanism and the first control signal. The Enzian, as were practically all German guided missiles, was directed to the target vicinity by radio control. When the target approach was within the range of the homing device, the latter took charge of the missile's final run in. Coincidence or line of sight navigation was used under favorable conditions; however, several methods were accepted for night or reduced visibility use.
Airframe
The Enzian E-4 airfram was a flying wing type having no horizontal stabilizer and a fixed vertical fin. Control was effected through trailing edge flaps which act together as elevators and differentially as ailerons. The basic dimensions are as follows:
Length: 4 meters
Span: 4 meters
Maximum Diameter (Fuselage): 0.88 meters (Circular cross section)
Root Thickness: 20% root chord
Tip Thickness: 10% root chord
Wing Area: 5 square meters
Airfoil: NACA symmetrical; no twist.
Dihedral: Zero
Chord Root: 1.25 meters
Chord Tip: 0.98 meters
Sweepback: 30 degrees
Weight (E-4 Complete): 1,800 kilograms
Empty (including Warhead): 833 kilograms
Warhead: 500 kilograms
Motor: 97 kilograms
Fuel: 550 kilograms
Assisted Take-off Units: 320 kilograms
Airframe (including Control Gear): 333 kilograms
For the purposes of an air-to-air missile, the fuel weight was reduced to 150 kilograms and the assisted take-off units discarded.
The airframe was designed to be built of wood because of current metal shortage, but provisions were made for conversion to metal stampings. The production process was to use hot plate gluing methods for fabricating a pressed or plywood material.
Aerodynamic Peculiarities and Characteristics
Aerodynamically, the E-4 appears normal. Its stability in flight tests was accepted as good. The E-4's design performance follows:
Maximum Velocity (Design): 300 m/sec
(Measured Walther Motor): 240 m/sec
End Speed Launching: 24 m/sec
Minimum Speed for Safe control: 55 m/sec
Vertical Range: 16,000 meters
(Measured Walther Motor): 7,000 meters
Horizontal Range: 25,000 meters
Turning Radius: 500 meters
Propulsion Unit
Although the Walther power plant was originally intended fo rthe Enzian and was used in the test flights, it was entirely unsatisfactory and replaced by the Conrad motor.
The bifuel liquid rocket motor uses Salbei (92% HNO3 + 8% H2SO4) and Visol, the ratio of weights being 1.4 to 1. The total quantity of fuel, 550 kg, is exhausted in 72 seconds during which time the thrust is reduced from its initial 2,000 to 1,000 kg at the end of burning. As pressure reduction between the air bottle and liquid tanks is through a simple orifice plate, the progressive reduction in the combustion chamber operating pressure is the direct result of the air bottle's gradual exhaustion. Equal pressure is applied to both liquids and metering is effected by the resistance of the connecting pipes and not that of the nozzles. The total impulse (108,000 - 110,000 kg sec) corresponds to a mean S.I. of 199; however, Wurster states that the mean propellant consumption 5.5 gm/kg sec rises to 5.6 at start and end of burning operation and that the S.I. is of consequence approximately 182.
Although the mixture, Salbei and Visol, is spontaneously inflammable, the Enzian motor used an electrically ignited powder starter in the combustion chamber to effect ignition. This system had the advantages of smoother ignition and less risk of explosion than spontaneous combustion. A further precaution against explosion was taken by starting the Salbei feed first by shortening its supply pipes and setting its bursting disks at slightly lower pressure than those of the Visol system.
The propulsion unit's arrangement, dictated by C.G. considerations, as follows: (1) Air bottle; (2) Visol tank; (3) Salbei tank; (4) Combustion chamber. The air flask was originally inflated to a pressure of 200 atmos.
The liquids are retained in their tanks by means of bursting disks selected to rupture at 15 atmospheres at entry and 36 atmospheres at exit. All tanks are made of mil steel 2 mm thick and no corrosion treatment, enamel, or protective coating was employed as the only General Staff requirements was that the containers should withstand 6 months storage after being filled with Salbei and fuel.
The weights of component parts of the motor are as follows:
Combustion Chamber: 24 kilograms
Air Bottle: 19 kilograms
Spherical Tank: 30 kilograms
Spherical Tank: 24 kilograms; 97 kilograms
Fuel Weight: 550 kilograms
Effective S.I. Fuel and Motor = 199 x (550/647) = 170
Relative to use of an air pressure fuel feed system versus a turbine-pump system, Wurster states that according to German figures, the former is lighter up to impulses of 200,000 kg/secs and has the additional important advantage of requiring no time for running up to speed. He cited the Me-163 which requires 4-5 seconds to run the turbine up to its operational speed of 30,000 pointing out that such delay is prohibitive for a flak rocket.
Intelligence and Control Systems
Operationally it was expected to use the Enzian in the following manner: Launch it toward and direct it to the target vicinity under radio control using the new German equipment Kogge and either line of sight or radar navigation. When the missile's approach to the target came within the operating range of the particular self-seeking head employed, the latter would assume control and direct the Enzian to the target's proximity on a modified homing course. The proximity fuze at pre-determined distance activates the warhead which was designed to ensure maximum coverage and effective damage of the target from 45 meters.
It is considered pertinent to note here that the Germans were doing extensive research work on the theory of homing courses. Their principal investigations appeared to be based on compromises lying between a pure chaser or homing course and a straight interception route procured by interjecting self-navigation into the intelligence system
Initial planning provided for the Enzian's use of one of several typo homing devices and proximity fuzes currently being developed or combinations of the above. Tests had not progressed beyond operation with the standard German radio control, the 6-meter "Strassburg-Kehl", developed by Telefunken and Strassfurt Rundfunk. The "Kogge" designed by Telefunken to operate on a 24-cm wave length was destined for use in the production Enzians.
The I.R. device, "Madrid", developed by Kepka of Vienna, an acoustic device developed by Telefunken and Messerschmitt, or an electronic device were projected for use as homing heads. These articles had been laboratory tested by their manufacturers only as separate entities.
Metamorphosis of the internal control system from two axis stabilization involving the use of four gyros to acceptance of one axis stabilization using a Horn gyro having two gymbal rings is outlined above under experimental testing. Standard Siemens electric servos are used to actuate the control surfaces.
Warhead and Fuzing
Three types of wrhead of equal weight, 500 kilograms, were projected for the E-4. The type which seemed to have accrued the most favor among the Messerschmitt engineers and the local flak officers was built up of a metal shell or container 1.5 mm thick. The shell was lined with cylindrical pellets cast of mild steel 20 by 30 mm containing an incendiary core! The explosive cast into the resulting cavity contained a booster charge and fuze in its forward end on the longitudinal axis.
Tests of the above type warhead showed that it could be expected to put 1.5 pellets in an area of 1 square meter at a range of 65 meters.
The second type of warhead incorporated 550 small rockets driven by gunpowder which had been developed by one of the SS laboratories and were to be used as part of the armament of the Me-262. The rockets were mounted in the warhead to fire forward in a 30 degree cone from a maximum range of 300 meters; their effective range, however, was 550 meters and at that range each rocket was considered capable of destroying a bomber.
The third type warhead was straight explosive dependent only on concussion to destroy the target.
Both proximity and self-destruction fuzes were provided. The proximity fuzes were projected on the I.R., Electronic, and Acoustic principles; however, the latter had essentially been dropped by the designers as the maximum range at which the actuating impulse was of sufficient magnitude was too small to derive most effective results from the warhead.
Auxiliary Equipment
Four powder jets assisted take-off units delivering a total of 6,000 kilograms thrust for 4 seconds are used to launch the Enzian. The JATO's produced by Rheinmetall-Borsig weigh 80 pounds each. They are attached by explosive bolts which release the cases by firing at the end of burning. Small wings fitted to the JATO's assist in the jettisoning.
Next Time: Rockets (Part 12)
Source: German Explosive Ordnance Vol. 1: Bombs, Rockets, Grenades, Mines, Fuzes & Igniters
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