Nike - First Test Firings Jan 1946 - Jan 1947
For record purposes, the missiles were identified by a double set of labels; viz., a "Round Number" and a "Missile Number," The Round Number was a chronological firing test serial number, the dummies being identified by alphabetical letters beginning with Round A and powered flight launchings by numerals beginning with Round 1. The Missile Number, which served as a factory identification number, consisted of two symbols separated by a hyphen, the first part denoting the design year or model number and the second part (after the hyphen) denoting a chronological manufacturing serial number. Dummy missiles were serially designated by letters placed after the model number prefix-e.g., NIKE-46-A-while powered missiles were distinguished by numerals, beginning with Missile No. NIKE 46-1.First Experimental Firings
In the fall of 1946, test facilities at WSPG were readied for the first experimental series of NIKE firings. Fourteen missiles had been manufactured and delivered, four of which were inert (wooden) dummies and ten were powered but uncontrolled missiles, The dummy missiles were constructed by mounting production-type main and control fins to solid fuselages made of laminated mahogany. All test missiles were ballasted with lead to bring the gross weight to 1,000 pounds, as originally specified for the final weapon. The expendable portion of this weight amounted to 312 pounds-220 lbs. oxidizer, 80 lbs. fuel, and 12 lbs. air. The basic design characteristics of the NIKE-46 missile and its components have already been discussed.
Before conducting the first flight test, one missile (No. 46-1) was static-fired to prove power plant operation, to test the servicing and firing equipment, to determine the effect of motor operation on performance of the radar beacon and missile instrumentation equipment, and to familiarize the field personnel with the techniques involved. After the static test firing on 17 September 1946, Missile 46-1 was returned to the DAC Santa Monica Plant, where it was inspected and overhauled. It was then sent back to WSPG and flight fired as Round 4 of the test series.
Flight firings of the NIKE-46 missile began at WSPG on 24 September 1946 and continued through 28 January 1947. Of the fourteen missiles provided for the 1946 test program, three wooden dummies and eight powered but uncontrolled missiles were actually expended during this series of firings. A ninth round (Missile No. 46-4) was recovered intact, though damaged, after a booster misfire. (One dummy and one actual missile-46-D and 46-10-were not fired in this series but were reserved for Future test purposes.) A brief account of the first twelve flight firings is given here.
The first three unpowered (dummy) tests were entirely successful. The boosters detached themselves at altitudes of about 2,000 feet and the missiles coasted to altitudes of 30,600, 43,300, and 42,150 feet, respectively. These unpowered tests convincingly demonstrated the feasibility of vertical take-off under boost thrust, acceleration to a supersonic velocity of about 1,900 feet per second, and stable flight before and after booster separation.
The first unguided powered missile tests followed in rapid succession. They were spectacular and full of dramatic surprises. The very first one, fired on 8 October 1946, made a completely successful flight, reaching an estimated peak altitude of 140,000 feet. The second round traveled 17 miles and the eighth over 25 miles, demonstrating not only more than the predicted range capability, but also the need for safety destruction in case of a runaway. Both the second and eighth rounds reached a peak altitude of over 100,000 feet.
However, the other rows were unsuccessful because of poor booster separation and motor troubles. The third round, which reached a peak altitude of only 58,900 feet, exhibited intermittent motor operation and poor separation of the missile-booster combination. The separation problem repeated itself in the fourth and fifth rounds; the sixth and seventh rounds were wrecked by booster explosions during launch; and the ninth round was a booster misfire.
Failure of motor operation in Round 4 and complete loss of the motor after separation in Round 5, together with other evidence of structural damage, led to the conclusion that same violent lurch was caused and damage was inflicted by the booster upon the missile aft section during separation. This trouble was presumably due to some irregularity of thrust or premature burn-out of one or more of the four rocket boosters. To remedy this problem, guide rails were installed between the missile and the booster, and the booster nozzles were canted so that the line of thrust of each booster would pass through the center of gravity of the missile. Some thought was given to changing the entire booster concept; however, it was decided to continue with the four-booster units, at least for the time being, so that other parts of the program could advance on schedule.
Information obtained from missile tracking radars was very meager since the tracking beacon was silenced in every instance by violent events during or at the end of boost, frustrating the planned tracking tests. The troubles encountered in the first few rounds were diagnosed with reasonable certainty and corrected; however, in most of the latter rounds the beacon was damaged along with other items in the rear of the missile. The fact that the beacon failed during boost rather than at separation indicated the existence of more problems than those attributed to poor separation.
The discovery, analysis, and clarification of problems encountered during these experimental firings came as a result of elaborate instrumentation. Arrangements had been made with WSPG to obtain maximum coverage of the missile tradectory From the network of cinetheodolite stations then available, This was still in a somewhat rudimentary stage in 1946; time correlation of stations was precarious and indirect, frame sequence was four exposures per second at best, and evaluation was unmechanized and painfully slow. Thus, the accuracy of position data obtained was hardly sufficient to determine acceleration to a significant precision.
It was therefore fortunate that provision had been made to equip the missile with airborne instruments. In the early period, before the advent of reliable radio telemetry, this was done by means of a flight recorder which consisted of two missile-borne motion picture cameras photographing two sets of instruments in flight. These instruments were axial and transverse accelerometers, a fuel regulator pressure gauge, several aerodynamic pressure gauges, and a heliograph, The latter was a specially developed optical device which, with the aid of four extreme wide-angle lenses, produced a pictorial record of the relative position of the sun and the horizon, From these records, the history of the attitude and orientation of the missile in space could be reconstructed by a somewhat laborious evaluation technique. But first the impact of the missile on the ground had to be located by a search team and the armored film cases had to be recovered from the wreckage. It was often necessary to dig a considerable depth before retrieving the film records. To improve the chances of film records surviving the impact, film magazines were protected by means of armored cases and shock-absorbing packing, and the velocity of impact was reduced by blasting the main fins during descent.
The photographic records disclosed a number of significant episodes. One was the occurrence of a prolonged stable corkscrew motion of Round 2 on its spectacular 17-mile flight. A somewhat similar motion was observed on Round 3 which was also troubled by malfunction of the pressure regulator in the fuel feed system, and a chemical fuel fire started in flight which eventually set off the fin destructor, causing the missile to tumble during its subsequent descent. Improvised booster-borne cameras gave pictorial evidence of kinematic separation difficulties.