The Messerschmitt 'Enzian' (initially the Flak Rakete 1) was a German experimental guided Surface to Air Missile of World War II built by Messerschmitt AG.[1]

Description

The Enzian was designed as a response to the masses of American and British Heavy Bombers, such as the Avro Lancaster and B-17, that were plaguing the German war industry.

Unlike other contemporary German missiles like the Rheinmetall-Borsig Rheintochter or Henschel Hs 117 Schmetterling which were precision weapons designed to effectively destroy one aircraft at a time, the Enzian was fitted with a massive 500kg (1100lb) high explosive warhead designed to create a explosion and shockwave large enough to knock down several bombers at once.

In total, it is estimated that up to 60 of the missiles were built, and that 38 were tested, beginning in April 1944. Due to the deteriorating manufacturing ability of the Third Reich and concern for the continuation of production of the Me 262 and Me 163 projects, the development of the Enzian was cancelled.

Guidance

The Enzian was launched from a long rail built on top of a modified 10.5cm Flak 39 or 8.8cm Flak 18 pedestal, and was controlled by an operator on the ground via radio in a manner similar to that of the Hs 117 Schmetterling. Once launched, a flare lit in the tail of the missile, which was observed by a controller on the ground. The controller would fed corrections to the operator, who would make the corrections using the Kehl/Strassburg System codenamed 'Parsival' (FuG203/230). 'Parsival', a common form of radio control in the Luftwaffe, used four separate radio frequencies, with each one used for a separate movement; up, down, left ,right, and a fifth for detonating the warhead. This was designed to prevent the entire rocket becoming uncontrollable in the case of a faulty transmitter/receiver. It was hoped, much like with the Hs 117 Schmetterling, that in blind conditions it would be able to use the Mannheim-Riese radar system, codenamed 'Rheingold', which worked similarly to the Würzburg fighter control system. It involved two sets of radar transmitters, one tracking the missile and one tracking the target, which fed a Cathode Ray tube. The operator would use the same joysticks he used to control the missile visually, but now he would be watching the two dots being projected on the CRT and attempting to overlap them. It was hoped that eventually this process could be automated.

Design

The Enzian sitting on the launch apparatus.

The Enzian shared a very similar design to the Messerschmitt 163 rocket fighter designed by Alexander Lippisch, with a small rounded fuselage, short swept-back wings, and only vertical stabilizers; no elevators. Pitch control, much as with the Me 163, was achieved with the 'elevons' (a combination of elevators and ailerons). The two large vertical stabilizers were non-moving, only control of roll and pitch were afforded. It had a diameter of 0.88 meters (2 feet, 10.8 inches). The Design made specific use of very inexpensive materials, due to the shortages Germany was experiencing due to the war. Almost the entire structure was built out of moulded plywood, and the aluminium skin was very thin and low-quality. The device also made specific use of technology that was very well understood at the time. This was almost enough to score the approval of Luftwaffe officials to put it into full production. The design ran into problems with its balance in the the testing, as the designers had not fully grasped the importance of aligning the missiles axial center of gravity and thrust lines, resulting in off center thrust and loss of control. This was later fixed and the missile performed as expected in tests.

Propulsion

The Messerschmitt Enzian was propelled in testing by a combination of four Schmidding 109-533 diglycol-fuelled rockets, the same as employed by the Hs 117 Schmetterling, and a Walter R1-210B sustainer engine. The Four Schimdding rockets were lit at launch to lift the heavy liquid fuelled Walter Sustainer rocket off the launch rail. The four launch rockets gave a combined thrust of 7000 kg (15,400 lb). The Walter Engine was fuelled by a combination of SV-Stoff and Br-Stoff (Red Fuming Nitric Acid with Dinitrogen Tetroxide and Petrol)[2] and gave about 2250 kg (4960 lb) of thrust. The set of two fuel turbopumps were powered by steam from a small amount of Hydrogen Peroxide, just as with the Aggregat-4 (V2 missile). It is believed that about 15 of the motors were built, all used in the testing of the Enzian. Another, simpler engine was designed by Drs Konrad and Beck of the Deutsche Versuchsanstalt für Kraftfahrzeug und FahrzeugMotoren (DVK, the German Aviation Propulsion Experimental Establishment) to replace it in the production version. The new motor used S-stoff (Red Fuming Nitric Acid, Sulfuric Acid, Nitric Acid, Ferric Cholride) and Visol (Vinylisobutyl ether, Aniline) delivered by compressed air rather than the steam turbopumps. The simpler production engine gave better thrust figures of 2500 kg (5510 lb) of thrust falling to 1500 kg (3300 lb) by the end of its 56-second burn time, which was more favorable, as it prevented the rocket going above its maximum Mach number and becoming unstable.

Operation

Operation was slightly more difficult than other German missiles where due to the speed of rocket the operator could simply point his guidance system at a target to score a hit. The Enzian required the operator to lead his targets due to its much slower speed. Furthermore, the planned radar proximity or time delay fuzes being developed were not fully functional or available at all, so the operator had to rely on his controller's estimates of the targets for the detonation altitude.

References

  1. Ford, Roger. Germany's Secret Weapons of World War II. Chartwell Books, Inc. 2013. Pages 137-139.
  2. Sutton, George P. History of Liquid Propellant Rocket Engines. American Institute of Aeronautics and Astronautics, Inc. 2006. Pages 764-773.
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