After World War II, the United States undertook a secret operation known as Project Paperclip, the aim of which was to exploit German scientists and engineers for American research, and to deny the technical expertise of these individuals to the Soviet Union. More than 1,600 scientists and their dependents were recruited and brought to the United States by Paperclip and its successor projects from the late 1940s through the early 1970s. Among these technical personnel were Drs. Wolfgang Noeggerath, Rudolf Edse and Gerhard Braun, who were employed in the Foreign Exploitation Section of the Air Documents Division, Intelligence, T-2, Wright Field beginning in 1945.
Dr. Braun was assigned to the Aircraft Laboratory, while Drs. Edse and Noeggerath were employed in the Rocket Laboratory. The author has uncovered little else about these engineers beyond their activities in Germany. Dr. Braun worked for the German Luftwaffe and was largely responsible for the creation of the “Hecht” and “Feuerlilie” anti-aircraft rocket projects at LFA Braunschweig. There, he directed activities concerning high-speed missiles with Drs. Edse and Noeggerath, who were responsible for propulsive details in addition to their other projects.
On October 15, 1945, the Army Air Force requested a design for an anti-aircraft rocket from Drs. Braun, Edse, and Noeggerath. Dr. Braun was primarily responsible for the organization and principle details of the project. The Army requested that the anti-aircraft missile incorporate the following performance characteristics:
|Velocity at 60,000 ft||Mach 2|
|Payload||100 – 200 lbs|
In response, the engineers issued their proposal report on December 27, 1945. The missile study, humorously labeled the CH-64 “Chow Hund” (Hund of course being the German word for “hound”), was quite advanced for its day and incorporated what had been learned in previous experiments with the Hecht, Feuerlilie and other German anti-aircraft missiles during World War II. The following is a summary of this rather technical but interesting report.
Dr. Edse prepared the analysis and comments concerning the booster rockets.
His personal experience and general theoretical investigations had shown that boosters were employed to advantage in anti-aircraft rockets. This was due to the fact that the missile received the kinetic energy of the boosters more or less without penalty, since the mass of the boosters did not require further lifting or accelerating after they were exhausted.
Inasmuch as the rocket was to fly at supersonic speeds, it appeared practical to install boosters sufficiently powerful that sonic speed was attained by the time the boosters dropped. In this manner, the difficulties of achieving an aerodynamic form suitable for both supersonic and subsonic speeds were avoided; other known solutions of this problem involved a compromise of supersonic aerodynamic characteristics. It was therefore possible to choose dimensions especially for the supersonic speed range since negligible stability difficulties were encountered at subsonic speeds due to the high accelerations during takeoff.
A high initial acceleration shortened the time between takeoff and the strike at the target, providing a tactical advantage. Acceleration was not of such magnitude, however, that the stress limitations of the power plant and steering apparatus was exceeded, or that a weight penalty was introduced by very high combustion pressures in the boosters, which would have necessitated greater wall strength.
For these reasons, four powder boosters with identical combustion chambers developing a total thrust of 48,000 kg (105,600 lbs) for a combustion period of three seconds were decided upon. Thus, the total impulse of the booster rockets was equal to 3 x 4 x 12,000 = 144,000 kg/sec (317,000 lb/sec). The booster rockets would have burned 720 kg (1,587 lbs) of powder. The burning time of the boosters were not of long duration, since steering was practically impossible until the boosters were jettisoned and since the boosters were to have been dropped from as low an altitude as possible. The altitude chosen for the booster release was approximately 500 m (1,640 ft). The boosters were attached to the rocket fuselage in a similar arrangement to the ones used on the Feuerlilie and “Enzian” rocket projects in Germany. If attached behind the rocket, the boosters almost certainly wouldn’t have damaged the main rocket when released, but tandem mounting had the great disadvantage that the center of gravity was shifted towards the rear, necessitating exceptionally large control surfaces.
In order to achieve light weight, the walls of the combustion chamber had to be relatively thin, and combustion had to take place at low pressure. The full benefits from this weight saving could not be completely realized, however, since the thrust necessarily decreased with a reduction in the rate of expansion.
Experiments were to have determined the type of powder used. Double Base Powder (Nitroglycerine – Nitrocellulose), Di-nitro Di-glycol Powder, and Penta-Erithrite-Tetra-Nitrate were to have all been investigated; such powders were considered of great importance for the future development of rockets. It was also intended to further develop powders that possessed extremely high combustion velocities in a low pressure range, which would permit the use of plastic materials for the construction of rocket combustion chambers, eliminating the need for a nozzle.