NIKE-47 Missile
Because the NIKE-47 was designed to serve generally the same functions in tests of launching and unmaneuvering vertical flight as the NIKE-46, the basic configuration of the 1946 missile was retained. However, in light of the previous year's test results, several modifications were made
to incorporate newly-designed equipment.
The missile boat-tail section was redesigned and strengthened, with corresponding booster structural changes, for improved application of boost thrust and smoother separation or the booster from the missile. Improved rigidity of the booster assembly was effected by an overall strengthening of components, together with structural additions to give improved guidance of booster along launcher rails, to place the boost thrust against the missile base, and to prevent side movement of the booster relative to the missile during separation. Pointed caps which had previously served to streamline the booster motors and apply the thrust to the trailing edge of the missile rear fins, were deleted. The after-body of the NIKE-47 was designed to rest snugly in a cylindrical sleeve mounted within the booster structure. This arrangement afforded positive contact between the booster and missile during separation, thus preventing the booster from developing an angle of attack or sideward velocity before the beet-tail was sufficiently clear of the booster structure, as had been experienced in some of the 1946 tests.
A number of changes were also made in the internal design and performance characteristics of the multiple rocket booster to correct the separation problems arising from uneven or unequal thrust forces during the boost phase. The single Aeroplex K-6 propellant grain used in the NIKE-46 booster was replaced with two grains of Aeroplex K-14, which burns at a slower rate and with consequent lower chamber pressures. The thrust was reduced from a nominal 22,000 pounds to 18,000 pounds per motor, but the duration of burning was extended from about 2 to 2.5 seconds. Changes were made to give more positive support to the propellant grain, and measures were taken in the field to keep the propellant grains at fairly even temperatures during a conditioning period prior to the firing. A new igniter was also developed.
The power plant system for the NIKE-47 was rebuilt around an improved design of the Aerojet Model 2l-AL-2600 acid-aniline motor. This motor was ten pounds lighter than that of the NIKE-46, but it possessed essentially the same capabilities, delivering 2600 pounds (sea level) thrust for about 21 seconds. In the new power plant system, a single- unit inertia-actuated starter valve-propellants feed regulator replaced the two previous separate components. Burst diaphragms in the propellant tank air inlet lines not only prevented premature mixing of the fuel and oxidizer, but also the premature entry of propellants into the motor.22
NIKE-47 Test Program
Five dummies (without motors) and four powered missiles were fired in the NIKE-47 series. These tests were conducted as a continuation of the tests begun in 1946 to study launching techniques, and to obtain additional aerodynamic and performance data an the missile in free flight.
The NIKE-47 firings were conducted in the following order:
Date | Round No. | Missile No. 9-22-47 | D | 47-E | 9-26-47 | E | 47-F | 10- 7-47 | F | 47-G | 10-16-47 | G | 47-H | 10-23-47 | H | 47-1 | 10-28-47 | 10 | 47-12 | l0-30-47 | 11 | 47-13 | 12- 9-47 | 12 | 47-15 | 12- 9-47 | 13 | 47-16 | |
The five dummy missiles (Rounds D through H) were made of hollow steel bodies with standard missile aft sections and fixed fins. Satisfactory flights were obtained in all dummy rounds, their peak altitudes ranging from 29,300 to 34,000 feet. The boosters for these rounds were equipped with nozzles outwardly canted (four at 15o and one at 17.5o) to minimize any turning moment about the center of gravity due to uneven thrust cessation among the four independently burning rockets. Clean separation was indeed achieved. Telemetering transmitters carried on the boosters gave good, informative records of booster burning pressures. With the various improvements in powder gain support and in nozzle manufacturing, it seemed that the quadruple boasters now gave an acceptable performance and separation. however, the deviation from the predicted climb path was excessive. Precise inspection and measurements of the canted nozzles disclosed dimensional variations which gave rise to unpredictable burning behavior and fusion, and hence thrust eccentricities, the elimination of which would have required the development of new manufacturing processes. To obviate this difficulty, it was decided to return to straight nozzles for the four powered missile launchings.
Following the dummy tests, four powered but uncontrolled missiles were fired, all of them with the new Aerojet power plant already described. With one exception, they gave evidence of satisfactory boost and separation. In one round the separation method performed admirably under extremely adverse conditions. Two of the four rounds attained peak altitudes of about 120,000 and 115,000 feet in smooth trajectories; the other two rounds were frustrated by premature detonation. Analysis of the aerodynamic data obtained in the tests showed that the drag was very Close to the originally estimated values or much higher than the 1946 values. This effect was to be further investigated in the 1948 flights.23
Launcher and Accessory Devices
Several improvements were made on the launcher. Its four 20-foot rectangular cantilever rails were replaced by heavy walled steel tubing which was easier to repair or replace in case of accidental damage. Guiding action during launch was now applied entirely to the booster structure rather than partly to the missile body. A second launcher was built portable so that it could be disassembled for transportation and set up on any flat surface in the field for firing. Erection was accomplished by means of a hydraulic strut instead of the electric winch of the earlier models. Eventually the launcher rails were shortened by three feet so that the effective guide length was reduced from fifteen and one-half feet to twelve and one-half feet, which was considered to be the best compromise between guidance and accessibility.
A number of accessory devices were developed which greatly facilitated the assembly, checkout, and handling and servicing of the missiles at the Proving Ground and enabled the crews to carry on a continuous work schedule.24
The general component function program of the four phases (vis.,
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, vas worked out in much greater detail during the
---- start page 49 -5
---- very poor image - very fat booster
Photo from http://www.wsmr.army.mil/paopage/Pages/NikeAj.htm
---- "Page 50 consisted of a graphic that ceased to be legible."
as per Claus Martel MARTEL-CR@ccsmtp.redstone.army.mil
----- start page 51 -6
next planning conference held in October 1947 Even though some problems
of boost dispersion and power plant operation bad 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 WSPD 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 allowable tolerance
requirements. (This radar vas 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.25
Computer Development
The actual construction of many of the commuter 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 paint
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-r0clret booster which bad been perfected by the
Allegany Ballistics laboratory. This booster was designed for the
JPL-JHU26 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 rocket
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.27
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,
leaning ample vent area for the motor flame. A conical steel cap with a
---- start page 54 -9
graphite tip was attached over the booster chamber end to protect it
from the beat and erosion of the looter 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.28
During field feats 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 2.6DS-51,000 solid propellant
rocket29
and the other of four AeroJet JATO 2.5KS-18,000C-2
rockets.30
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 adapted for future
NIKE field tests. No further development of Aerojet cluster boosters
was scheduled, but they continued to be fired until the stock was
depleted.31
Launcher Development
To 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, designated as No. 3, is shown in figure 7. 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.
Figure 7. Launcher No. 3-- Single-Rail (WWPG Photo)
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 40 mm 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.32
1948 Field Test Program
During the summer and fall of 1948, 26 full-scale NIKE firings
were conducted at WSPG. These were divided into three test series--48-0,
48-1, and 48-2--each based on a separate design of the NIKE for the phase
development plan of the project. From these designs emerged NIKE Models
484 and 490, which were to constitute the final missile configuration.
Three NIKE missiles (Rounds 31, 32, and 33) not expended in the 1948
program were returned to DAC for modification of the ram pressure system
and control system. These were reserved for use in the first part of
the 1949 field tests.
NIKE 48-0 Test Series
In a group designated as the NIKE 48-0 series, four Model NIKE-47 live
(powered) missiles and one dummy, which had not been expended the
previous year, were modified and fired in free-flight tests with the new
Allegany single thrust-rocket booster. The primary objectives were to
test the new launcher and booster, to obtain aerodynamic data on the
booster-missile, and to continue to free-flight performance study. (See
Table No. 2 of Appendix 5.)
The single booster, equipped with four suitably large trapezoidal
fins, was first tested on dummy Round J, 17 June 1948. Although launching
and early boost was satisfactory, this first flight was terminated by booster
fin failure prior to separation.
After modifications had been made to strengthen the booster fins,
three powered missiles (Rounds 14, 15, and 16) were fired in vertical
flight tests, and a fourth (Round 17) at a slant elevation of 40o
north from vertical. In three of these rounds the motor burning time was
shorter than expected. In the first test, a reduction in burning time
of 2 or 3 seconds was apparently caused by incomplete filling of the
acid tank, but high lateral accelerations could have uncovered the fuel
tank outlet. In the third powered round, burnout occurred 5.5 seconds
early. Uncovering of the tank outlets appeared to be the only possible
explanation in this case. Burning time was two seconds short in the
slant elevation firing, but due to the nature of the trajectory it was
expected that some propellant would be trapped in the tombs as the openings
became exposed. The firing at slant elevation presented no serious problems
of launching, boosting, or missile performance.
Telemetered data obtained from missile-borne Bendix equipment, added
for the 1948 tests, indicated lateral accelerations up to 4.5 to 6g during
motor burning, apparently as the result of asymmetric thrust. The flight
in which the motor had reached full burning time was detonated 1.9 seconds
after burnout because the horizontal velocity was in excess of range safely
limits. Because of the reduced thrust, the peak altitudes and times of
flight were lower than predicted, but analysis of data further confirmed
that the aerodynamic performance of the missile was satisfactory and the
estimates of most aerodynamic characteristics were fairly accurate.
An improved explosive charge--17 ounces of cast TNT and 3 ounces of
cast Tetryl-had been installed in the NIKE-47 powered missiles. As before,
the charge could be detonated by beacon command or by a fail-safe system
in the missile. In the four rounds fired, command detonation was accomplished
when called for and the missile detonation was
effective.33
NIKE 48-1 Test Series
Most of the 1948 field program was devoted to tests of the NIKE 48-1
---- start page 60 -15
series, consisting of four Model NIKE-47 dummies and 13 NIKE-48 live rounds
of the cluster booster-missile configuration (See Table 3 of Appendix 5.)
Three of the dummies were fired in launching and free-flight tests; one was
allocated for a functional check of the detonator system operation. The
live missiles, of the same aerodynamic design as the NIKE-47, were equipped
with roll stabilization and steering controls, operated in response to orders
from a missile borne programmer. The programmed control tests of these
missiles were divided into two phases: Phase I calling only for repeated
roll stabilization from induced spins, and phase II for pitch maneuvers
in yaw and roll stabilized flights. Accordingly, the missiles were built
to fulfill these test functions. For Phase I, the forward control fin
mechanisms were locked. The power plant and general structural design
of the NIKE-48 was very similar to the NIKE-47.
Of the 48-1 powered missile series, all but the first, which was destroyed
by a booster explosion,34 were successful
as far as launch, boost,
and separation were concerned. In most of the 48-1 rounds, the motor operation
was also successful; however, there was continued evidence of lateral
accelerations produced during the burning phase, apparently as a result
of eccentric motor thrust. In one firing (Round 27), the motor produced
thrust only for about 7 to 8 seconds. Test records indicated that the
fuel system burst diaphragm only partially ruptured, causing an abnormally
lean mixture and reduced cooling flow; the motor chamber wall was burned
through near the nozzle entrance.
Other than this instance, there were no significant occasions of premature burnout.
The roll stabilization, however, gave considerable trouble. Its nature was
tedious to explore and could not have been readily understood had it not
been for a detailed and extensive analysis of the 28 channel
records of the telemetry. As noted above, the first NIKE 48-1 test
(Round 18) yielded no information because of a booster explosion. The next
three phase I tests (Round. 19 through 21) showed that the aerodynamic roll
damping was smaller than had been predicted and that the addition of artificial
damping was required. This was accomplished by the installation of a roll-rate
gyro by means of which a damping signal was fed into the aileron control circuit,
beginning with Round 22. At high angular rates its signal is sufficiently large
to dominate the situation and cause the ailerons to deflect in the direction to
stop the missile independent of the momentary roll position. When the roll rate
is reduced to a low value, the roll position gyro regains control and brings the
missile to the desired orientation.
The fifth missile roll stabilized when commanded, so the sixth was
fired as a phase 2 steering control round. This missile (Round 23)
shared a violent steering instability with resulting oscillations. The
absence of any high frequencies formed a basis upon which to change the
circuits for another steering control round. However, before the next
steering round was fired, it was discovered that the only explanation for
several discrepancies in data from Round 22 was that the roll gyro brush had
been grounded. The stabilizations of Round 22 could be explained as entirely
fortuitous, as all of them had occurred under conditions where
some of the previous missiles had roll stabilized.
Therefore, another Phase 1 (Round 24) vas fired to gain further
information on the performance of the roll control system with the rate-
gym installed. The gym operated satisfactorily in this test, but the
need for more roll damping was indicated. This vas obtained by doubling
the rate-gyro voltage in Round 25, which was also a phase 1 missile.
Greatly improved roll stabilization resulted, so the second phase 2
missile was fired as Round 26.
Although considerably improved over the first phase 2 missile, instability
was still present and an intensive investigation of the steering
circuitry vas undertaken. To verify the aerodynamic and missile dynamic
data to be applied in this study, Round 27 was fired with a missile wired
for step fin-position commands, in contrast to standard step accelerations,
and the resulting transients were to give the necessary information.
Round 27 was not adequate for this purpose, however, because of
motor and timer malfunctions. Round 28 was then successfully fired for
the same objectives.
On the basis of these data and other information obtained in the
study, the steering circuits sere redesigned and Rounds 29 and 30 were
fired after the changes. These rounds confirmed the general analysis and
final remedy was tested in Rounds 31, 31, and 33 during May 1949 (see
Table 4 of Appendix 5). The remedy consisted of a refinement of the ram
pressure responsive attenuator in the servo circuit, not only in the roll
control system but henceforth also in the suitably changed shaping
network of the steering order
circuit.35
NIKE 48-2 Test Series
Another part of the 1948 NIKE missile program comprised the development and
test of the NIKE 48-2 missile, a revised aerodynamic design. During the NIKE
design studies early in 1948, trajectory computations indicated that, to obtain
optimum range, the effective main fin area of
the missile should be reduced by one-third. This conclusion was applied in the
new fin design for the NIKE 48-2, and in addition, the fin thickness
was reduced from 6% to 2.5% to decrease wave drag. Revisions to provide space
for larger warheads were also made in the fuselage design, including an increase
in length from 235 to 255 inches, changing the
shape of the after-body from a boat-tail to a cylindrical shape, and
attachment of an external tunnel fairing along the body to house
electrical wiring and plumbing
lines.36
Four dummy missiles of this
configuration were fired in August and September 1948 (see Table 5,
Appendix 5).
During June and July, however, tests of a 7.5% scale model in the APG
supersonic wind tunnel indicated that the NIKE 48-2 possessed
unsatisfactory stability and roll characteristics. These tests resulted in
several major configuration changes, such as returning to the original
fin area, decreasing the distance between the control fins and main fins,
and installing four small tunnels instead of the single large tunnel.
This modified version, now known as the NIKE 484, vas assigned for
steering and roll tests to be conducted in 1949.37
Ancillary Activities
Planning Conferences. The sixth planning conference was held at
WSFG, in September l948 during the Phase l and 2 overlap. The seventh
conference followed in March 1949 at Santa Monica during the recess in
the firing program while changes were made in the missile which led to
the successful conclusion of Phase 2 in May 1949. In these conferences
the status of progress was reviewed and plans were mapped out for the
field program of Phases 3 and 4 scheduled for the winter of 1949-50, and
for a comprehensive 490 series of firings to be scheduled for the second
half of 1950, realizing that various improvements developed in the meantime
would require proof testing. This would move the complete NIKE
System Trials into 1951, which fumed out to be the earliest year in which
radar, computer, targets, and accessories could be ready for
them.38
During the latter half of 1949, progress continued on all aspects of
the project despite an austerity program which had been imposed on it.
No more missiles after the three in May could be flown in 1949, but sixteen
missiles of the 484 type were prepared for field firings which
actually took place between January and April 1950. They covered the complex
steering tests originally planned as Phase 4, with such variations
as were dictated by a host of cross-coupling troubles which
cropped up. These problems were overcome by systematically tracking down their
origin from the elaborate telemetry records. It was during these test firings
that predetermined pitch and yaw acceleration orders
were transmitted to the missile from the ground via radar-to-missile
communication circuit for the first time. The magnitude and timing of
these commands were set up prior to the flight on a versatile time-clock
programmer in the radar.
Radar
The missile tracking portion of the NIKE Ground Radar System, having
been completed and thoroughly tested at Whippany, was transported by air
and truck to WSPG in November 1949 The complete radar system consisted
of an Antenna Trailer, a Radar Control Van, a modified M2 Optical Tracker,
and a 400-cycle Engine Generator. It was set up at radar station site C
and connected to an existing Western Electric T14E1 plotting board. Check tests
were begun in December 1949, tracking a specially assigned B-26
target airplane which was equipped with a beacon and a receiver. Simulated guidance
commands were successfully transmitted over the radar-to-beacon channel and
recorded aboard. For comparison, the same airplane was
also tracked by the two high-accuracy Eastman theodolites permanently
installed at Dona Ana Camp and under the cognizance of the Army Field
Forces Board No. 4. Reflection tracking runs of the B-26 plane were also
made to determine its performance as a radar target.
The monopulse radar successfully tracked all missiles from the launcher,
through boost and separation, and in many cases to impact. Missiles fired into
clouds or at night were tracked without difficulty,
demonstrating the all weather reliability of the guidance system. Several
missiles were controlled manually toward a ground target location and the
communication system functioned satisfactorily down to very small angles of
elevation.39
Computer
Having reached the stage of a frozen circuit design, the detail design
of the NIKE Computer and the construction of its components progressed
rapidly. A considerable amount of equipment had already been completed and
was in the process of being tested as individual components. work was
concentrated on the construction of modulator amplifiers,
demodulators, switching amplifiers, and on the testing and improvement of
components. Manufacture of the data receiver and the synchro-data-transmission
units, with their precision potentiometers and extensive gearing, entered the
final stage with every indication of meeting the
stringent accuracy requirements.
Effort was also directed toward the electrical design of associated
test equipment. Of primary concern here was the so-called "test bay"
containing sufficient facilities to check overall computer operation on
a test problem basis in the field. Additional portable equipment was
to be designed for general maintenance of the computer.40
Missile
An analysis of available flight test data indicated that steering response
and roll behavior should be adequate under all significant conditions with the
recently revised control circuits providing ample
damping. New IBM Fourier techniques were developed to compute the transient
behavior of the missile in acceleration controlled test flights. These
calculations and the flight test success to date created sufficient confidence
for the planned Phase 3 series of tests to be skipped and the limited number
of test missiles better exploited. Good agreement of
flight test stability measurements with wind-tunnel observations was secured.
Despite the stability-maneuverability dilemma brought on by the non-linear moment
characteristic in the transition from small to large angle of attack, an
acceptable compromise was sought and eventually found by shifting the center
of gravity farther aft in the missile.
Several changes were made in the missile. The interior equipment was
repackaged for better accessibility and space utilization; the three
oil accumulators were manifolded to insure that all control components
would remain operative together; and some changes were made in the telemetry
system to adopt more shockproof and more linear transducers, improved
sampling commutators, and finer ram pressure gauges. The ram pressure
probe was embodied in a new nose spike-type telemetry antenna. Wind tunnel
tests trying out ailerons with various types or aerodynamic balance features
designed to reduce the hinge moments and thus to conserve oil,
led to a compromise solution for the simple trailing edge aileron
configuration. To provide some of the ballast needed on non-warhead
missiles, the main fins were machined from solid aluminum alloy.
In an effort to avoid premature motor stalling when transverse or
negative accelerations cause propellant liquid to surge or slash and
uncover the tank outlets, several designs of conical internal hoppers
and flexible bladders, which would keep the outlets covered until all
fuel was exhausted, were developed and tried under laboratory and test
stand conditions. The answer to the minimization of eccentric thrust
was eventually found in rigorous control of nozzle manufacture and alignment.
The only other change introduced in the power plant structure was in the
tank configuration. The propellant and air tanks were made into an
integral unit.
Launcher
Many improvements and additions were made to the launching equipment,
including an experimental, extremely light, portable monorail launcher.
Although the original monorail launcher weighed only 5,000 pounds, an
effort was made to develop one that would be extremely light so that it
could be readily transported by air and assembled by manpower alone. Such
a launcher was actually built. By virtue of efficient design and extensive
use of aluminum alloy, the overall wight, excluding ballast boxes,
was reduced to 2,050 pounds. A demonstration proved that the components
could be satisfactorily handled by an eight-man crew, requiring less than
ten minutes to unload and assemble the launcher. however, the lightweight
model was considerably more expensive than the standard model; it was
stored after having been used for only a few test
firings.41
NIKE 484 Test program
Although the NIKE 484 field tests were primarily intended to demonstrate
missile behavior under severe and complex pitch and yaw command
conditions, they served a number of secondary purposes dictated partly by
necessity, partly by opportunity. They did indeed demonstrate NIKE to be a
true guided missile, remotely controllable from the ground, thus proving
the command guidance link of the missile-tracking radar with the
beacon and order transmission links over the monopulse radar beam. The
sixteen missiles gave further proof of the suitability of the present
configuration, components, structure, and methods of construction. Several
variations were introduced which indicated the feasibility and desirability
of moving the center of gravity closer to the center of pressure, and of
starting the sustaining motor after booster
separation.42 A
detailed outline of test results is given in Table 6 of Appendix 5.
In general, roll stabilization of the missiles was very good and at
times excellent. Telemetering records and radar tracking indicated that
the missile received and accurately executed all commands. But these
results were not accomplished without incidents and problems. For
instance, it was found that first order dynamic structural bending
vibrations of the missile body at about 20 cycles per second (cps) were
being sensed by the control accelerometers and rate gyros, thus
catastrophically upsetting the response of the missile to control orders.
This trouble was finally eliminated by relocating the accelerometers
closer to a node and inserting attenuation at 20 cps in the rate gyro
circuit. Another unforeseen problem was encountered with some of the
control valves, which functioned erratically and caused some intermittent
control discontinuities. Several circuit changes and the establishment
of proper oil cleanliness procedures were necessary to eliminate this
difficulty.
Figure 11. NIKE Missile 484-50 in Launcher (WSPG, 20 Apr 50)
In four of the last five rounds, the low-power klystron beacon was
replaced by a new, more powerful magnetron beacon with gratifying results.
Round 43 was deliberately guided through the transonic phase and for a
considerable time in the subsonic regime with satisfactory response in
pitch and yaw.
Several rounds were launched from the new portable lightweight monorail
launcher which gave excellent service. launch, boost, and separation
from the single booster were successful in all cases. One round carried
a new angle of attach meter which provided aerodynamic stability data
confirming wind-tunnel measurements. Designed to give an accurate measurement
in subsonic, as well as supersonic flight, the new instrument was
developed by DAC, in conjunction with G. M. Giannini & Company. It
telemeters the angles of pitch and yaw.
The 484 field tests proved that the prototype design was satisfactory
and that it could be scaled down by a third without impairing its accuracy.
This change favorably increased the frequency response and was therefore
incorporated in a subsequent model which was carried by many of the NIKE 490
series missiles.43
Planning Conference
The eighth planning conference, held at WSPG late in March 1950,
concerned itself, first, with a digest of flight test results as far as
they had accrued; and second, it considered conclusions and recommendations
for the next phase of the test program. The then remaining six
484 missiles were to bracket all parameter ranges and insure proof of
proper roll and steering control at high altitudes and low dynamic
pressures or wherever else it may be critical. Of the next series of missiles
to be produced-and designated as Model 490--another batch of at
least sixteen was to be assigned to a precise performance test program in
1950 before embarking upon the official NIKE system trials in 1951. All
of these tests had to be scheduled and interspersed with the activities
required on behalf of the development of the tactical version
NIKE I.44
This stage of the NIKE development program was divided into two major
periods-one devoted to construction and preparation, followed by the
first part Of planned performance tests in the last three months of 1950.
Ten of the assigned sixteen missiles had been expended when performance
tests were interrupted by unexpected troubles. Following the elimination of
trouble sources, the test activities were resumed, with the next six rounds
being fired between April and July 1951.
Radar
Early in 1951, the radar, which had given generally satisfactory
service as a missile tracking and steering order transmitter since its
installation, was subjected to several improvements and refinements preparatory
to the system tests. The single motor drive far elevation of
the antenna mount, which was found to be marginal, was replaced by a dual
motor drive. Extensive laboratory and environmental tests had been conducted at
Whippany to improve the electrical boresight stability of the angle error
detectors and the adjustment stability of the automatic gain control circuits.
As a result of these tests, better circuits and
components were developed and installed in the radar at WSPG. Another innovation
was a monitoring and test unit, which made it possible for an operator to check,
in less than a minute, all the adjustments of the order communication circuits
on a built-in oscilloscope. All of these changes
improved radar performance. The coded pulse system, which was introduced to
eliminate radar-missile command interference, functioned perfectly.
During the first tests at WSPG, a very accurate method for bore
sighting the radars was developed. (This method was carried through to
the tactical NIKE I System.) A small waveguide born was mounted on top
of a 60-root pole located about 600 feet from the radar antenna. A small X-band
rapid-fading (RF) test source, under remote central of the radar, provided RF
power to this horn by means of a waveguide running up the
pole. Small optical targets were also located on top of the mast on each side
of the RF horn by the same parallax distance as the optical telescope
on the radar was located from the electrical center of the antenna. With
this equipment and a special technique of "dumping" the antenna to
eliminate the effect of any ground reflections, it became possible to
boresight the radar electrical axis to the optical telescope to an accuracy of
about 0.05 mil. From this point on, the optical telescope was
used as the reference in the system tests when both missile and target
radars had to be boresighted with respect to each other.
----- start page 74 -29
To show the accuracy of reflection tracking, a number of boresight
and instrument films were taken with an improvised installation of synchronized
cameras to record data from the radar and the computer. The
effort was frustrated by various malfunctions, so a new and more
elaborate camera, system had to be developed for the system tests.
A second radar, for target tracking, was under construction at
Whippany. In general, this radar was similar to the missile radar, except for
the omission of missile steering order equipment and certain
mechanical and electrical improvements. All the improvements and refinements
the missile radar were built into the target radar.
Computer
Meanwhile, the construction and testing of the NIKE computer
components had been completed, along with the assembly and wiring of the
entire computer. Preparatory to shipment to White Sands for use in 1951
system tests, the computer was put through the preliminary stages of
qualitative tests on the system tester.
A second computer, to be retained for use in the laboratory system
tester, was in the final wiring and preliminary testing stage. The test
bays, to be associated with both computers for checking purposes, were in
process of construction.45
Missile
Based on observations made during the previous (484) test series, a
number of changes were introduced in the missile structure, which became
identified as the 490 family. Some of the innovations were prompted by the desire
to improve performance and facilitate production, while others
were intended to eliminate difficulties previously experienced. The most important
of these changes are briefly described below.
In general, the changes noted in items 1 through 4, above, gave very
satisfactory results. The other changes, however, resulted in difficulties.
While the delayed starting of the sustainer motor (item 1) was satisfactory
for all intents and purposes of the test, it added the
complication of short motor burning time. This early burnout--noted in
all but one of the first ten firings-was attributed to the bursting of
propellant (acid line) diaphragms during boost acceleration and the consequent
loss of oxidizer (acid) prior to motor ignition. The two flight tests conducted
with the bladder-type propellant tanks (item 7) were unsuccessful because of
sealing difficulties (oxidizer bladder unable to withstand negative accelerations
at the end of boost). This approach was abandoned in favor of a fixed hopper-type
tank structure which worked
satisfactorily in later firings. Early in the program, it became apparent that
the other two changes introduced in the 494 missile were
causing a recurrence of certain roll and steering oscillations which had been
eliminated during the 484 test series. Specifically, the change in the hydraulic
control valves (item 5) gave a persistent 2-cps oscillation in the steering
circuits; and the decreased moment of inertia (item 6)
resulted in loose roll control which network changes failed to eliminate
completely. While these oscillations did not significantly impair the missile
control, they seemed to be wasteful of hydraulic oil and they
prevented the gathering of clear-cut aerodynamic performance data.
Even though the objectives of the 1950 firing program had not been
fully achieved, the program was discontinued with the firing of the tenth
missile (Round 59) in December 1950, so that the information already
available could be studied in more detail and necessary modifications
accomplished. The ten missiles fired in the fall program exhibited satisfactory
launch, boost, separation, and motor ignition. With a few minor exceptions,
the radar tracking and command link performed in a very
satisfactory manner. Detailed results of these ten firings are given in
Table 7 of Appendix 5.46
The first three months of 1951 were devoted to the elimination of
trouble sources and modification of the remaining six 490A missiles,
which were to be launched as a part of the Spring Supplementary Firing
Program. The hydraulic valves were thoroughly tested and then redesigned,
reducing the valve plunger port overlap ratio as much as possible and
thus reducing the non-linearity of valve characteristics. Changes were
also made in the electrical network to increase the gain margin at large
phase angles. Hydraulic fin locks for the launching period aid not perform
any more positively than zero g steering orders and were therefore
discarded after the fall tests in favor of the latter method. The roll
control circuitry was changed to make the servo gain a function of
dynamic pressure and thus tighten up the control to overcome troubles
attributed to the small roll moment of inertia. To prevent loss of
oxidizer during boost and thus insure normal motor burning time, a new
propellant control valve, with inter-linked burst diaphragms, was developed
for the acid-aniline motors. Be an alternative, three of the six
NIKE 490A missiles were equipped with experimental acid-gasoline power
plants.47
Some of the supplementary test rounds were also equipped with
arming devices and fuzes, the proper function of which was demonstrated
by telemetry and by detonation of an explosive spotting charge. These
arming devices, designated as Type T93, had been developed by Frankford
Arsenal and tested in the laboratory. The spotting charge was designed
to supply a burst indication for those system test missiles which were
not to carry live warheads. It consisted essentially of a smoke-producing
explosive contained in a tube which extended across the center warhead
compartment. Both ends of the charge were ignited simultaneously to give
a visible smoke puff and thus simulate a warhead burst.48
The NIKE 490A Supplementary Firing Program (Rounds 60 through 65)
began an 12 April 1951 and continued intermittently through 14 July 1951.
It was primarily designed to prove the various remedies noted above, with
secondary objectives of testing alternatives and accessories, preparatory
to the first R&D system tests in October 1951 These field tests were
very disappointing, to say the least. Test objectives were successfully
achieved in only two of the rounds; the other four were marred by component failures,
chiefly in the control system. A brief account of these
field tests is given below. (For further details, see Table 8 of Appendix 5.)
The first two rounds (60 and 61) were fired primarily to test the
effectiveness of modifications made in the acid-aniline power plant system to
insure full duration of motor burning. Secondary objectives were
to test the Frankford arming device and spotting charge. Both rounds
made satisfactory flights. Burning times were normal and there was no
indication of propellant loss during boost. The Frankford arming devices and
spotting charges operated satisfactorily.49
Round 62 was flown with the control system fully operable to demonstrate
revisions made in the control network, and to test the acid-aniline
power plant system under maneuvering conditions. A high frequency
oscillation in the pitch and yaw steering channels caused the malfunction
of this round. Except for some sporadic burning just before burnout, the
missile motor continued to operate satisfactorily during the oscillations.
The primary objective of Round 63 was to test the new acid-gasoline
power plant system in flight. It was frustrated by an explosion during
the starting phase. No repetition of this experiment could be scheduled
during the R&D Program; however, the obvious advantages of a missile
motor burning a fuel that would be readily available almost anywhere
remained as an incentive.
Rounds 64 and 65 were flown to test further revisions in the central
network, as well as changes made in the acid-aniline power plant system
to correct hard start conditions noted in earlier rounds. In Round 64, a
malfunction occurred before separation (missile lost propellants and had
sporadic motor burning during boost), resulting in erroneous command
acceleration levels. In Round 65, the booster and power plant operation
was normal during launch phase: however, a malfunction occurred in the
missile at take-off, causing an unbalance of the control signal. Difficulties
experienced in both of these rounds were attributed to component
failures in the control system.50
The component development and proof test phase of the NIKE project
was scheduled to end with the last 490A missile firing (Round 65) in July
1951, and demonstration of the complete R&D System was to begin with the
firing of Round 66 (490B series) in October 1951. However, the latter
490A test results clearly showed that complete reliability of all control
system components still had not been achieved, and that further
modifications and supplementary field tests would be required in order
to preclude the recurrence of malfunctions during R&D System firings
against drone targets. The necessary control circuit modifications were
later completed and successfully tested in Round 66 on 16 October 1951.
The NIKE missile was now ready for the supreme test--firing against
drone aircraft.
{----- end of chapter 3}
January 1948 to May 1949
System Tester. At Whippany the design and construction of the
Analog System Tester had proceeded to the point where many of the computer
components had been thoroughly bench tested. The target simulator
part of the machine was essentially completed. When supplemented by
parts simulating missile aerodynamics, it was pressed into service as a
missile trajectory computer which took over in a more versatile and
rapid manner the sort of tasks which had bean preliminarily fulfilled by
the improvised trajectory plotter made in Santa Monica in 1947.
June 1949 to April 1950
(May 1950 to July 1951)
Sixten of these modified missiles, designated as the 490A series,
were scheduled to be launched during the fall of 1950. The purpose of
these firings was to test the efficacy of the above listed changes, and
to insure that the 490 missile could respond accurately to steering
orders in preparation for system tests at WSPG in the fall of 1951.