Single-Plane Steering Test Program
The general component function program of the four phases (viz., Phase 1, Roll Control; Phase 2, Steering Control; Phase 3, Step Control; and Phase 4, Complex Control), which had been outlined in a previous planning conference, was worked out in much greater detail during the next planning conference held in October 1947. Even though some problems of boost dispersion and power plant operation had not been fully solved, it was decided to begin these tests in the summer of 1948. Meanwhile, plans were made to devote additional specimens of the 1947 model to a determined attack on the unsolved problems and to conclude their tests and evaluation in time to catch up with the control function tests, even if they should overlap. Such an overlap did occur and ran into the months of July, August and September 1948.Radar Development
Apart from the missile performance test program, the design of the missile-tracking radar progressed and took definite shape in 1948. Principal effort was directed toward the design and construction of the monopulse angle tracking radar model for the missile tracking and ground steering phase scheduled to start at WSPG in mid-1949. For the NIKE systems field test phase, the duplex mount arrangement of the original plan-two antennas separated by 12 feet on a common rotating platform- was abandoned in favor of two identical radar mounts placed 50 to 100 feet apart. By December 1948, the components of this radar were well along in manufacture and the set was scheduled for systems test early in 1949.
Considerable effort was also devoted to the design of components for the radar, especially the rapid-fading plumbing and associated receiver circuitry. After extensive laboratory experimentation, a satisfactory automatic gain control circuit was developed. The various wave guide plumbing parts were made by an electroplating process that produced very smooth internal wave guide surfaces within the allatable tolerance requirements. (This radar was destined to transmit steering orders from a clock-governed programmer to the missiles during Phase 4 tests in 1950 and remain at WSPG well beyond the R&D System Tests in 1951 and 1952.)
In the meantime, the aircraft tracking data collected at Whippany during 1947 and 1948 on the modified SCR-545 monopulse system were being analyzed for the influence of range and glint on tracking smoothness and accuracy.Computer Development
The actual construction of many of the computer components was started in 1948 after accuracy studies had established the equipment requirements. It was determined that error sources would not lead to significant degradation of the NIKE system performance, that they were not serious, and were significant only in a few places In the computer.
The design of components and major assemblies had progressed to the point where the overall computer assembly arrangement was established and the design of computer housing started. A decision had been made to employ the synchro data transmission alternative between radars and computer, and design work on this equipment had reached a stage corresponding to other computer sections.
Another decision made at this time concerned the use of plotting boards rather than oscillographs to display the course of the engagement. Plotting boards present the picture at a considerably enlarged scale and give a permanent recording of the pre-launch predicted intercept point and the missile and target trajectories.Booster Development
Because of the uneven burning troubles experienced with the Aerojet cluster-type booster, a new and radical approach was tried in 1948; namely, that of a powerful single-rocket booster which had been perfected by the Allegany Ballistics Laboratory. This booster was designed for the JPL-JHU Bumblebee ram-jet to meet performance criteria similar to that established for the NIKE. Its double-base solid propellant of OV composition, prepared by the solvent method and cast with internal combustion surfaces, burned with nearly smokeless exhaust, while the Aerojet Paraplex rockets produced a dense smoke. The single-rocket motor alone was about 120 inches in overall length and 17 inches in diameter. Its average thrust over a burning time of 2.6 seconds was rated at 51,100 pounds, with a total impulse of 140,000 pound seconds. The propellant had a specific impulse of 187 pound seconds per pound.
In March 1948, designs were completed and fabrication was started to adapt the Allegany rocket as a single-unit booster for the NIKE. Naturally, the single booster had to be installed aft of, and in line with, the missile itself. This resulted in a rather long missile-booster combination, mainly because a space had to be provided between the booster and missile to avoid obstruction of the missile motor exhaust. The connecting structure was built in the form of a sleeve and ring attached to the front end of the booster can by means of struts or legs, leaving ample vent area for the motor flame. A conical steel cap with a graphite tip was attached over the booster chamber end to protect it from the heat and erosion of the motor flame. Because of differences in the center of gravity and the center of pressure in these missiles, a set of booster fins was designed to give positive subsonic and supersonic stability to the combination during launching. Each booster was to have four fins of modified diamond configuration mounted near the aft end of the chamber .
During field tests conducted later in the year, a comparative study was made of the two booster designs under consideration-one comprised of a single Allegany JATO T39 2.DB-51,000 solid propellant rocket and the other of four Aerojet JATO 2.5KB-18,000C-2 rockets. The performance characteristics of the two boosters were essentially the same; but from the standpoint of cost, assembly, and handling, as well as the possible tactical advantage of being smokeless, the single thrust-unit booster possessed definite advantages. Consequently, it was decided that the Allegany rocket would be adopted for future field tests. No further development of Aerojet cluster boosters was scheduled, but they continued to be fired until the stock was depleted.Launcher Development
Ta accommodate the long single booster, a new single-rail launcher was built. Its design was based on a refined pattern of the preceding Launcher No. 2 (portable, four-rail), in that an erectable rail assembly was supported on a flat tripodal base and the entire structure could be easily disassembled into manageable sections. This new monorail launcher was designated as No. 3. It weighed only about 5,000 pounds, in contrast to 12,000 pounds for the portable four-rail launcher. It had a loading height of 5 feet, an erected height of 18 feet, and an overall height of 35 feet when loaded with the missile and booster.
In the nine test rounds fired later in the year with the Allegany booster, the single-rail launcher was highly satisfactory, particularly in regard to the simple and rapid loading methods it afforded and accessibility for pre-firing servicing of the missile and booster. These factors had a significant bearing on the decision to change to the single booster for NIKE.
Based on the success of the new single-rail launcher, preliminary drawings were completed for a light-weight mobile launcher, incorporating the running gear of an M-2 40mm antiaircraft gun carriage. Possessing all major characteristics of Launcher No. 3, the new version was to be completely mobile and weigh about 3,000 pounds .