The Atlantic Missile Range begins at Cape Canaveral and extends 9,000 miles into the Indian Ocean. The mission of AMR is to provide exact data on all phases of a missile's performance, from launch through termination of flight. To accomplish this task, island tracking stations have been established. These stations are located at Grand Bahama Island, Eleuthera Island, San Salvador Island, Grand Turk Island, East Island-Puerto Rico, Antigua Island, Trinidad, Ascension Island and Pretoria-Republic of South Africa (not an island station). These range stations provide nearly all the data required. However, additional data on nose cone terminal and re-entry phenomena is also required.
The Air Force Missile Test Center recognized this need, and in 1960, the Air Force asked industry to submit proposals on a floating island station. This new program was called ARIS-Advanced Range Instrumentation Ships. In March 1961, 12 companies submitted Proposals and in May, Sperry Gyroscope Co., a division of Sperry Rand, was selected as the system manager. The letter of contract was let in June 1961. The Air Force then selected two ships out of the "moth ball" fleet. These ships Were the General Callan and the General Taylor. Both ships were built by the Henry J. Kaiser shipyards in 1944. They are of the 14,300 ton C4-S-A1* troop type and were chosen for the ARIS.
*In this Maritime Administration designation, C stands for cargo and 4 indicates the size of the vessel; S means steam propulsion and A1 shows a modification of the original design.system because of their size, range and economy of operation.
The ships' specifications are: Length, 520 feet; Beam, 72 feet; Depth, 44 feet; Draft, 25 feet; Normal Shaft HP, 9,000; Full Load, 14,300 tons; Sustained Speed, 17.3 knots; Fuel Oil Capacity, 2,687 tons; and Cruise Range, 6,000 nautical reties. Like the rest of the AMR stations, the Air Force has overall responsibility, with operation by Pan Am and instrumentation servicing by RCA technicians. There are 100 in the ship's crew and 100 instrumentation personnel aboard.
Modification of the ships for tracking purposes took place at the Bethlehem Steel Ship Yards in Brooklyn. This consisted of removing much of the superstructure to allow room for the antenna supports. Extensive room modifications were also necessary for equipment installation. In addition, ship machinery, including boilers, turbo generators, emergency diesels, etc. had to be repaired.
ARIS instrumentation can be classified into eight subsystems: Operations Control Center, Integrated Instrumentation Radar, Stabilization and Navigation, Communications, Data Handling, Telemetry, Meteorological and Timing.
Operations Control Center (OCC): This is the command post of the station during tracking missions and systems tests. This centralized control facility provides for smooth internal operation and assures proper integration of the ARIS station into the AMR operations. OCC personnel must perform the following activities during missions:
Coordinate with other AMR stations, aircraft and ships.
Review system and subsystem status.
- Assures correctness of ship's position, speed and heading.
- Monitor and countermand subordinate decisions.
- Select the source of sensor designate information.
- Synchronize the countdown clock at liftoff.
Integrated Instrumentation Radar (IIR): This consists of three integrated radars operating at C-band, L-band and UHF-band frequencies. The primary tracking device is the C-band radar utilizing a parabolic reflecting antenna thirty feet in diameter. Precision has been stressed in the construction of this antenna. This radar provides complete tracking data on re-entry bodies, from the acquisition of the missile to its impact. Similar to C-band radar is the L/UHF band radar. This utilizes a dual frequency antenna forty feet in diameter. The center 18 feet is used for UHF-band radar and the remaining portion for the L-band radar. These radars also provide data on rs-entry.
Stabilization and Navigation: The exact location of the ship must be known if the tracking data is to be of any value. A complex navigation system continuously supplies this information on the ship's position, heading, velocity and vertical reference. This system consists of SINS (Ships Inertial Navigation System), a navigation control console, a water speed-measuring system (E-M log), a star tracker, a teletypewriter, a Mk-19 gyro-compass and Sonar Bench Mark equipment. The heart of the system is SINS. It contains three gyros and two accelerometers. Because of gyro drift, this inertial system develops errors that increase with time. This draft or precision error is determined by a star fix. A star tracker measures the star altitude by locking on the star's position. A computer solves the celestial problem and a navigation fix is made. Sonar bench marks are also used as a navigational aid for updating SINS accuracy. The bench mark is dropped over the side in a known position. It has an acoustic transponder mounted on a buoyant tank which is anchored by a battery container. When the sonar set is triggered, a reply is received from the transponder. The elapsed time, as a function of range, is measured to each beacon thus locating the ship with respect to the bench marks.
Communications: This is a highly sophisticated communications system designed to meet all external and internal needs. This includes one of the most powerful radio communications systems ever installed on board a ship. One lO,O00 watt and two 2,500 watt high frequency transmitters provide complete long range voice, teleprinter, and high speed data communications up to lO,O00 nautical miles from Cape 0anaveralo An interior communication network has been developed for the use of the instrumentation personnel. This network consists of three types of intercom stations, each varying in channel capacity, which link key shipboard instrumentation personnel.
Data Handling: The data handling system consists of the central data conversion and control equipment and a Univac 1206 stored program digital computer. The conversion equipment has two main purposes: to serve as an interface between the major systems (SINS, C-band radar, L/UHF-band radars, telemetry) and the Univac 1206 computer, and to store all trajectory and non-trajectory data collected during a mission. The overall accuracy of the data conversion equipment is 0.4 percent. All stored information is in digital form, having been transformed by the conversion equipment. The data processing needs are met by the Univac 1206 digital computer. This is a general-purpose machine of small size and high resistance to shock, vibration and unusual climatic conditions. This computer performs such functions as system checkout, target acquisition, target tracking, data format, data transmission, navigational fixing and updating.
Telemetry: The telemetry system is used for acquiring, tracking, receiving and predetection recording of telemetry data from the re-entry vehicle. The system is capable of either independent or integrated operation with other sensors. It can be used to aim other tracking sensors to a proper angle cf acquisition and it can be slaved to the C-band radar or computer for position information° A 30-foot parabolic antenna is used for telemetry reception.
Meteorological: To aid AFMTC in the analysis of missile performance and the scheduling of tests the ships provide data on atmospheric pressures, density, wind direction and speed of sound. This is accomplished through surface weather equipment, weather balloons and high altitude ARCAS rockets.
Timing: The timing system provides real-time codes and indexes for time correlation of pertinent data. These codes are distributed in various digital serial formats throughout all the systems for accurate time correlation of all recorded data. The time code and indexes will maintain time correlation, relative to Cape Canaveral timing, within l0 micro-seconds at distances up to 10,O00 miles. Two radio systems provide this synchronisation.
The general operational procedure of the ARIS ships will be as follows:
- The ships will sail prescribed courses in the vicinity of the expected impact points, measuring position accurately with reference to surveyed sonar beacons.
- The communications system will receive post-burnout signals from Cape Canaveral.
- The computer will integrate the equations of motion of the missile faster than real time to determine an acquisition point prior to the missile's arrival Using measured values of latitude and longitude from SINS, a continually corrected stable acquisition point, relative to the ship, is acquired.
- SINS will supply heading, pitch and roll through the (CDCE) central data conversion and control equipment to the computer, which combines these with the acquisition point. The result is digital acquisition orders.
- CDCE converts these orders to synchre voltages for drawing the antennas, to the proper position.
- The tracker which first acquires the missile is designated the master.
- The other antennas are slaved through CDCE with corrections for ship's flexure
- When the C-band radar acquires the missile, CDCE converts trajectory
and signal strength to digital form and records on magnetic tape.
- The missile path is plotted from the acquisition point to impact.
- After impact, recorded data is transmitted to waiting aircraft via telemetry and balloon snatch.
The development of the ARIS vessels was a challenge to the Air Force and industry in the field of digital handling. It was a problem of providing coordination and real-time control of very accurate interacting instrumentation equipment aboard a moving ship. Through Air Force management and industrial ingenuity, this integration was made possible.
The Advanced Range Instrumentation Ships (ARIS) will extend the Atlantic missile range into the South Atlantic and the Indian Ocean. ARIS will allow the AMR to be more flexible in launching direction and range of impact.
The prime mission of ARIS is accurate tracking and data gathering of re-entry vehicles. However, these ships will also participate in future projects like Dyna-Soar, Gemini and Apollo.