Michael Neufeld - The Rocket and the Reich

The one clear trouble spot was personnel. At the end of 1942 the air force had formed a special unit, the Flak Experimental Center Peenemünde (later Karlshagen), to staff the Wasserfall project and the new test stands being built for it. The center paralleled the Army’s Northern Experimental Command in that it could pull Luftwaffe personnel from other units and assign them to Peenemünde-East. This unit, which was not formally connected to the air force’s own base at Peenemünde-West, had another dimension as well: Its headquarters staff served as a sort of supervisory office for Wasserfall. The growth of the Flak Experimental Center was slow, however, because other Luftwaffe units obstructed transfers. Moreover, in the summer of 1943 Milch became furious when he found that Luftwaffe personnel assigned to the Army had been pulled into A-4 work. Because of the extreme pressure to produce results, Peenemünde had clearly exploited the interservice project to prop up the ballistic missile program. 78

Those troubles aside, however, Wasserfall appeared to be proceeding satisfactorily until January 1944, when the missile’s optimistic schedule collapsed. At the end of that month Ludwig Roth wrote a memorandum to his boss, design bureau chief Walther Riedel, indicating how unrealistic was the Air Ministry’s requirement for the delivery of a complete set of Wasserfall production drawings by April 15. That deadline had been advanced a month on Milch’s promise that more draftsmen and designers would be detailed to Roth’s office; some indeed were. But even May 15 was Utopian. Roth outlined a number of serious development problems, such as difficulties welding the interface between the wings and the tank structure, but the most fundamental were the choice of a fuel and the guidance system’s lack of definition. 79

The propellant problem arose from a lack of capacity in the chemical industry, caused, in all probability, by Allied air raids and the Armaments Ministry’s lukewarm support for the anti-aircraft missile program. As a result, there was no adequate supply of Visol for the deployment of hundreds of Wasserfalls and other defensive missiles by late 1944, the expected date. The Visol would have to be mixed with other chemicals, but that implied the expenditure of further research time to find a combination with the same performance. A new fuel combination would also change the density of the propellant and would therefore alter the mixture ratio between it and the nitric acid oxidizer, which itself had been cut with sulfuric acid to lower combustion chamber temperature and prevent engine burnthroughs. An uncertain mixture ratio threw into doubt the relative size of Wasserfall’s two main tanks, which necessarily brought into question the entire structural design of the missile. Only in the summer of 1944 was Peenemünde able to settle on a fuel combination that performed well and had the same density as pure Visol, thereby salvaging the existing tank design. 80

The difficulties with guidance and control were even more fundamental. As Roth noted, even such a basic problem as the creation of a sufficiently powerful control system was unsolved. The need for the missile to maneuver imposed much more demanding requirements on the vane servomotors, which had to exert and resist greater aerodynamic forces than the same systems on the A-4. The program’s attempt merely to modify the existing Luftwaffe mass-produced hydraulic servomotors proved to be a failure, and substitute electrical servos were slow in coming. Further development would be required for both types, with the result that it was impossible to say in early 1944 what the final design of the Wasserfall control system would look like, or even which principle the servomotors would use. A final layout of the missile’s tail section was therefore impossible. 81

The situation in guidance toward the target was even worse. From the outset, it was assumed that the final Wasserfall guidance system would be based upon a modification of one of the existing “Giant” radars into a guide beam that would slowly turn the vertically launched missile in the direction of the enemy aircraft and bring it into the target’s vicinity. In the autumn of 1942 von Braun still believed, on the basis of information from Luftwaffe and industry experts, that the accuracy and discrimination of those radars would allow the guide beam to direct the missile to the target, whereupon a signal could be sent to trigger the warhead at its nearest approach. He and his informants significantly overestimated the capability of the radars, however, particularly in the case of a bomber stream, where they were unable to distinguish individual aircraft. Von Braun was nevertheless aware that a homing device in the missile would be desirable; by 1943 it became increasingly apparent that it would be a necessity if the missile was ever to come sufficiently close. Yet even the physical principle of a workable homing device was debatable in 1943–44, although infrared (heat-seeking) systems seemed the most promising. 82

In addition, the insufficient discriminatory capability of radar meant that Wasserfall needed a proximity fuse to trigger the warhead in the likely event of a near miss. Yet no such fuse was available. The United States was able to deploy a such a fuse on anti-aircraft shells in 1944, but only after a massive program to develop a miniature radar set that could withstand the shock of being fired out of an artillery piece. German resources were spread too thin to permit a similar success. Proximity fuse projects, like those to build homing devices, were started too late and were allowed to proliferate without adequate control from the Air Ministry, with the result that none produced a workable device during the war. Even with better management, however, it is unlikely that the Germans could ever have deployed enough proximity fuses or homing devices to affect the military situation even marginally, given their inferiority to the Allies in research and development resources and electronic technology. 83

Ironically, when Roth gave his pessimistic assessment of the state of guidance development in early 1944, he did not even assume that the preliminary version of Wasserfall would have a homing device, proximity fuse, or automatic guide beam, although all of those features would be needed if the missile was to be truly effective. At that time Roth did not even have sufficient information to lay out the interim guidance system, which was based on a joy-stick operated by a controller on the ground. This system was a modification of the transmitter and receiver developed to direct the Henschel Hs 293 glide bomb against ship targets. The bombardier maneuvered the projectile using a joy-stick in the attacking aircraft. The procedure had scored some significant successes against Allied shipping in the Mediterranean, but directing a supersonic missile against an airplane at distances scarcely visible to the naked eye was a somewhat more difficult problem. Various schemes were outlined in 1943–44, using a telescope or telescopes that would be radar-directed to follow the missile as it ascended and approached the target. The controller could maneuver the missile in his cross hairs, although obviously not at night or on a cloudy day. Some proposed variants also had a radar screen displaying the missile’s position vis-à-vis the aircraft, but that scheme was subject to all the limitations of 1940s radar technology. In any case, the joy-stick system was in such an underdeveloped state that in January 1944 Roth did not even have the layout of the missile’s various antennae. 84

Wasserfall’s problems did not end there. Earlier in January Milch had once again become infuriated that Luftwaffe personnel in Peenemünde-East were being employed on A-4 work. He demanded that they be returned full-time to Wasserfall within three months. Tension erupted as well over the arrangements for the mass production of the missile. Much to the disappointment of Roth and others at Peenemünde, Henschel always refused to accept the production contract because of its own burdens. The idea of using the Mittelwerk had also been considered, and the A-4 Special Committee had promised in May 1943 to organize the manufacturing process. But Degenkolb did not pay much attention to the project, which is not surprising in view of the A-4’s problems. In the spring of 1944 Peenemünde and the Luftwaffe did succeed in interesting Linke-Hoffmann in the prime contract, but they received little help from the Armaments Ministry. Speer and Saur found no reason to support the production of a missile that was so far from deployment, and they soon had the formal power to obstruct such a decision. In June, on Hitler’s order, Göring gave control of aircraft manufacturing to the Armaments Ministry. Milch found himself circumvented and resigned as a result. 85