Enzian E-4

Type: Surface To Air Missile (also could be used as Air-To-Air Missile)
Models: E-1 to E-3 prototypes, E-4 Production
Manufacturer: Holzbau Sonthofen
(designed by Oberbayerischen Forschungsanstalt Oberammergau)
First Launch: August, 1944
Number Produced: 60+

Length: 4 Meters
Span: 4 Meters
Maximum Diameter, fuselage: 0.88 meter
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

Complete: 1,800 kg.
Empty, including Warhead: 833 kg.
Warhead: 500 kg.
Motor: 97 kg.
Fuel: 550 kg.*
JATO Units: 320 kg.
Airframe (with Control Gear): 333 kg.
Aerodynamic Peculiarities And Characteristics:
Aerodynamically the E-4 appear normal. Its stability in flight was accepted as good.

Performance Specifications:
Maximum Velocity:
   Conrad Powerplant: 300 m/sec
   Walther Powerplant: 240 m/sec
End speed launching: 24 m/sec
Minimum speed for safe control: 55 m/sec
Vertical Range:
   Conrad Powerplant: 16,000 meters
   Walther Powerplant: 7,000 meters
Horizontal Range: 25,000 meters
Turning Radius: 500 meters

*Fuel weight reduced to 150 kg. and JATO packs removed when configured for the Air-To Air Role.


DESCRIPTION: The Enzian was conceived as a ground to air flak weapon. It's secondary purpose was that of an air-to-air weapon. Models E-1, E-2, and E-3 were the test and experimental airframes. 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 Walther biliquid used in the earlier designs. As the foregoing is the only major difference in the four models, they will be discussed as one.

   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 weight is 500 kg. The airframe is constructed of wood, having an over-all 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 kg. 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 kg for four seconds, giving the missile an end speed of 24 m/sec at 3.6g acceleration from a launch ramp 6.8 meters in length. The assisted take-off units are jettisoned after 5 seconds.

   Although it was anticipated that the E-4 would be used as an air-to-air weapon with slight modification, principally reduced fuel load, all experimental testing had been done from ground to air. A standard 88mm gun carraige 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 and elapsed time of 5 secondsis allowed bewtween 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 missiles 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 airframe 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 airframe was designed to be built of wood due to metal shortages, however, provisions were made for conversion to metal stampings. The production process was to use hot plate glueing methods for fabricating a pressed or plywood material.

PROPULSION UNIT: Although the Walther power plant was originally intended for the 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 ration 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 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 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 atmospheres.

   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 2mm thick and no corrosion treatment, enamel, or protective coating was employed as the only General Staff requirement was that the containers should withstand 6 months storage after being filled with salbei and fuel.

   The weights of component parts of the motor as follows:
Combustion Chamber: 24 kg.
Air Bottle: 19 kg.
Spherical Tank (Visol): 30 kg.
Spherical Tank (Salbei): 24 kg.; 97 kg.
Fuel Weight: 550 kg.

Effective S.I. Fuel and Motor=199x647=170

   Relative to use of the 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 it's 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 selfseeking 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 predetermined distance activates the warhead which was designed to ensure maximum coverage and effective damage of the target from 45 meters. (see section on warhead below.) 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 types of 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 seperate entities.

   Metamorphisis 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 in outlined above under experimental testing. Standard Siemens electric servos are used to actuate the control surfaces.

WARHEAD AND FUZING: Three types of warhead 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 1/2mm thick. The shell was lined with cylindrical pellets cast of mild steel 20 by 30mm containing an incendiary core! The explosive cast into the resulting cavity contained a booster charge and fuze in it's 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 have 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 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 of warhead was straight explosive dependant 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 principals; 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 jet assited take-off (JATO) units delivering a total of 6,000 kg. of thrust for 4 seconds are used to launch the Enzian. The JATO's produced by Rheinmetale-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.

Additional Images:

Enzian SAM mounted on a Flak 8.8cm gun chassis

Example at RAAF Museum at Point Cook, Victoria, Australia.

Example at RAAF Museum at Point Cook, Victoria, Australia.