The missile launches The following story are from thuleforum.
This is the best and only story I have found about the missile launches in Thule

NIKE MISSILE SITES, AT THULE AB, GREENLAND

NIKE MISSILE SITES THE UNOFFICIAL HISTORY OF A, B, C, AND D LAUNCH AT THULE AB, GREENLAND



THULE AB, GREENLAND 1959-1965
By MSgt Edward L. Hilton 12 SWS/MAO 1999-2000



INTRODUCTION

The advent of the world''s first land-based antiaircraft guided missile system, coupled with the growing threat of atomic attack by manned enemy bombers, brought significant changes in both the continental air defense structure and the Army''s antiair missions and organization.
The first came on 1 September 1954, when the Army Antiaircraft Command and its sister elements in the Air Force and Navy were combined into a single organization, the Continental Air Defense Command (CONAD), directed by the Joint Chiefs of Staff and located at Colorado Springs, Colorado.
This was followed, in 1957, by a realignment of the roles and missions of the three CONAD components.

The Army''s air defense role was expanded by the assignment of longer ranges and broader coverage for its antiair missiles.
Under CONAD, the Army was charged with point air defense by missiles fired from the ground at aerial targets not more than 100 miles away.
The Air Force was responsible for manned interceptors, area defense, and missile ranges over 100 miles, and the Navy for sea approaches.
Point defense included those geographical areas, cities, and vital installations that could be defended by missile units, which received their guidance information from radar located near the launching site.
It also included the responsibility of a ground commander for the air protection of his forces.

On 21 March 1957, the Army Antiaircraft Command was renamed the U. S. Army Air Defense Command (ARADCOM), a designation that more clearly defined the "all missile" role of the command. In September 1957, the North American Air Defense Command (NORAD) was formed to combine the air defense capabilities of Canada and the United States under one commander-in-chief, who also headed CONAD. The missile units of ARADCOM and its sister services were placed under NORAD''s operational control. In the United States, NORAD reported to the Joint Chiefs of Staff; in Canada, to the Chief of Staff Committee. The unified structure of NORAD gave the continental air defense system true "defense in depth." This strategy combined the dimension of distance with a variety of modern weapons, ready to meet and engage the enemy along the full range of his attack. While the ability to deliver a retaliatory blow remained the principal deterrent against atomic attack, improved air defenses heightened the value of the deterrent and promised to exact a high cost in any attack by manned enemy bombers.

The NIKE AJAX fulfilled the mission for which it was designed and for several years served as the free world''s primary air defense. However, even before deployment of the AJAX, if was realized that the weapon system possessed certain performance limitations that would prevent it from engaging formations of the faster, higher-flying jet aircraft. Though superior to conventional antiaircraft artillery against single targets at supersonic speeds and high altitudes, the AJAX target tracking radar was limited in the resolution of aircraft in formation and therefore ineffective against mass air attack. This radar had a tendency to wander from plane to plane in the attacking formation, with the result that the missile would pass between two targets and burst where no damage would be done. In view of the performance limitations inherent in the NIKE AJAX guided missile system and the rapid advancements in aircraft altitudes, speeds, and nuclear payload capabilities, the Ordnance Corps, in 1952, had begun feasibility studies of an improved air defense system that would be capable of countering the new aerial threat. These studies culminated in the second-generation Basic NIKE HERCULES system, which began replacing the NIKE AJAX in 1958; the Improved HERCULES system, which became operational in 1961; and the HERCULES Antitactical Ballistic Missile system, which became available in 1963.

WHY NIKE?

During the years immediately following the Korean War, the "ack-ack" of conventional antiaircraft artillery guns gradually gave way to the "ack-track-smack" of the NIKE AJAX, the first land based air defense guided missile system to be tactically deployed in the United States and allied countries. The conversion from guns to guided missile artillery began on 20 March 1954, when the first combat-ready NIKE AJAX battalion was tactically deployed at Fort Meade, Maryland, in the Washington-Baltimore Defense Area. Although conventional antiaircraft gun units continued to play important roles in augmenting the protection provided by NIKE AJAX battalions, the NIKE had already outnumbered them as early as December 1956.

NIKE AJAX batteries were installed around strategic sites in the Continental United Stares (CONUS) and overseas. Each battery was an integrated air defense guided missile unit that, with its command guidance system, could engage one aircraft at a time while maintaining continuous surveillance of all targets within the effective range of the system. Its primary mission was the destruction of long-range bombers having speeds of up to 1,100 mph. The maximum practicable range was 45,700 meters against aircraft at altitudes of up to 60,000 feet, but targets could be identified as far away as 128,000 meters, and a missile could be launched when its target was 75,000 meters from the battery.

The NIKE AJAX had a command-type guidance system with acquisition radar on the ground that detected targets and furnished initial data on their positions to a target tracking radar, also on the ground. The latter radar obtained accurate information on the path of the target and transmitted it to the control computer, while at the same time a ground-based missile tracking radar furnished the computer with data on the position of the missile. The computer generated guidance-command signals, which were transmitted to the missile-borne guidance and control system by way of the transmitter of the missile tracking radar. The AJAX missile was first propelled by a booster motor that burned a cast, doublebase solid propellant. The booster was jettisoned after burnout, and flight was sustained by a liquid propellant motor with jet engine fuel and red-fuming nitric acid for the oxidizer. The missile carried a conventional high-explosive Warhead.

The NIKE AJAX fulfilled the mission for which it was designed and for several years served as the free world''s primary air defense. However, even before deployment of the AJAX, it was realized that the weapon system possessed certain performance limitations that would prevent it from engaging formations of the faster, higher-flying jet aircraft. Though superior to conventional antiaircraft artillery against single targets at supersonic speeds and high altitudes, the AJAX target tracking radar was limited in the resolution of aircraft in formation and therefore ineffective against mass air attack. This radar had a tendency to wander from plane to plane in the attacking formation, with the result that the missile would pass between two targets and burst where no damage would be done. In view of the performance limitations inherent in the NIKE AJAX guid ed missile system and the rapid advancements in aircraft altitudes, speeds, and nuclear payload capabilities, the Ordnance Corps, in 1952, had begun feasibility studies of an improved air defense system that would be capable of countering the new aerial threat. These studies culminated in the second-generation Basic NIKE HERCULES system, which began replacing the NIKE AJAX in 1958; the Improved HERCULES system, which became operational in 1961; and the HERCULES Antitactical Ballistic Missile system, which became available in 1963.

World War II generated a tremendous leap in military technology, especially in strategic bombers, air-breathing missiles like the German V-I, ballistic missiles like the German V-2, jet-powered airplanes and atomic bombs. These advances in technology, combined with the Soviet Union''s threat of world domination in the post-war years, caused the United States to take action to prevent yet another war this century. And if deterrence failed, the objective was to limit the damage to its citizenry and war-making capability.

During the final months of World War II, several major defense contractors studied the likelihood that evolving technologies could produce guided missiles to intercept bombers and surface-to-surface missiles. One of these projects, called NIKE after the Greek goddess of victory, would grow to a full deployment of more than 240 missile sites in the United States. Operating these sites were nearly 45,000 active duty and National Guard soldiers. ARADCOM controlled these missiles and antiaircraft guns and a vast network of command centers to communicate with them.

Threat-wise, the Soviet Union dominated the scene; its bombers and ballistic missiles held center stage in decisions made to deploy defensive systems. Nationally, the focus will be on key decisions made in Washington. Administrations from Truman through Ford made tough calls in allocating resources within the nation and the military. Budgets, taxes and competing domestic needs caused decisions on deploying systems to be politically challenging, to say the least.

Within the military, the services interacted to accomplish the air defense mission. Actions by the Department of Defense (DOD), the North American Air Defense Command (NORAD), and the other services, especially the Air Force, included a competition for resources that developed into inter-service rivalry. Yet the rivals cooperated in many ventures to ensure national defense. The Air Force was responsible for "Area Defense", and the Army (ARADCOM) was responsible for "Point Defense".

ARADCOM, whose motto was "Vigilant and Invincible", was the last line of defense against attacking enemy aircraft. When deterrence became a part of the United States'' national strategy, ARADCOM was key and essential to that effort. From the first deployment of World War II-vintage antiaircraft guns in 1950 to the inactivation of the last NIKE HERCULES missile system in 1974, ARADCOM provided a deterrent to the Soviet strategic bomber threat for the U.S. homeland. During this period, the Army built, operated, improved and then dismantled a vast network of defenses. These defenses protected the nation''s capital, key industrial areas, ports, atomic weapon production facilities and Strategic Air Command (SAC) bases from air attack. One of which were the NIKE Hercules sites located at Thule Air Base, Greenland.

LAUNCH CONTROL SITES

A "typical" Nike missile site consisted of three parts: an integrated fire control (IFC) area; a launching area and an administrative area. In many of the sites, the administrative area was co-located with either the IFC or the launching area. This would affect the overall acreage of the "Nike site". The size (acreage) of the launching area was also affected by the number of underground magazines and the physical arrangement of the launcher sections. The size of the different IFCs was also affected by the type and number of radar on the site.

Unlike some modern missile systems, Nike was guided entirely from the ground, from firing to warhead detonation. The electronic "eyes" (radar) and "brain" (computer) of the Nike system were located on the ground, within the Integrated Fire Control Area.

At the IFC area, hostile aircraft were first identified by means of an acquisition radar (AR). This radar was manned 24 hours per day, scanning the skies for indications of any hostile aircraft. "Friendly" aircraft were automatically identified by means of electronic signals generated by IFF ("Identification Friend or Foe") or SIF ("Selective Identification Feature") equipment. In practice, this target information would normally have been received from Air Force long range radar sites, by means of the Air Force''s SAGE (Semi Automatic Ground Environment) system and other sources including Army "Missile Master" and related facilities, in order to provide an advanced warning for the missile batteries.

Having acquired and positively identified a hostile aircraft, a second radar, the Target Tracking Radar (TTR) would be aimed at and electronically "locked onto" it. This radar would then follow the selected aircraft''s every move in spite of any evasive action taken by its pilot. A third radar, the Missile Tracking Radar (MTR) was then aimed at and electronically locked onto an individual Nike missile located at the nearby Launcher Area.

Both the TTR and MTR were linked to an "intercept computer" located at the IFC Area. This analog computer continuously compared the relative positions of both the targeted aircraft and the missile during its flight and determined the course the missile would have to fly in order to reach its target. Steering commands were computed and sent from the ground to the missile during its flight, via the Missile Tracking Radar (MTR). At the "moment of closest approach" the missile''s warhead would be detonated by a computer generated "burst command" sent from the ground via the MTR.

For surface-to-surface shots, the coordinates of the target were dialed into the computer and the height of burst was set. At the precise moment calculated by the computer, the warhead would be command detonated via a signal sent via the MTR. Alternately (and, presumably as a back-up system) the warhead could be exploded via "contact fusing" when striking the selected target or target area.

The mission of the Integrated Fire Control (IFC) Area was:

  • Identifying and selecting targets
  • Requesting the launch of a missile
  • Guiding that missile to within kill distance of the target
  • Sending the detonate (explode) command to that missile.

At Thule AB the Integrated Fire Control Areas were known as A, B, C, and D Control. A Control was located at Dundas Village, B Control at North Mountain, C Control and D Control on South Mountain. Of the four control sites, only C Control still stands, visible off the road on South Mountain.



Bldg # Purpose Year Demolished
01600 Unknown Unknown
01601 Dining Hall Airmen 1985
01602 Dormitory Airmen 1985
01603 Administration Office 1985
01604 Electric Power Station Building 1973
01605 Guided Missile Autonavigator Facility 1973
01607 Guided Missile Autonavigator Facility 1973
01608 Guided Missile Autonavigator Facility 1973
Vault 7 Unknown Unknown



The Integrated Fire Control (IFC) area was located on a hill or high place for best practical radar views of targets. At Thule, they were located on North and South Mountains. Because the earth is quite spherical ("round"), the higher you are above the surface of the sphere, the more surface and air above that surface you can see. The radar waves used by the Nike system travel in quite straight lines, like light. (Some other lower frequency radar waves have somewhat more complex possibilities.)

The Integrated Fire Control (IFC) area was surrounded by a stout fence, and guarded by armed troops. In general there was one gate (for the access road) through the fence, past the guardhouse. This was manned by an armed guard anytime the gate was open. Life, the international situation, and the troops were quite serious.



Bldg # Purpose Year Demolished
01609 Dining Hall, Airmen 1973
01610 Guided Missile Autonavigator Facility 1973
01612 Guided Missile Autonavigator Facility 1973
01613 Dormitory, Airmen 1973
01614 Guided Missile Autonavigator Facility 1973
01616 Guided Missile Autonavigator Facility 1978
01617 Supply Issue Shop 1973
01618 Electric Power Station Building 1973
01619 Dormitory, Airmen 1973
01621 Electrical Power, Station Building 1974
01623 Storage check out and assembly 1973
01629 Storage check out and assembly 1973



Bldg # Purpose Year Demolished
01911 Supply Issue Shop 1974
01913 Dining Hall, Airmen 1974
01915 Dormitory, Airmen 1974
01916 Guided Missile Autonavigator Facility 1973
01917 Dormitory, Airmen 1974
01920 Guided Missile Autonavigator Facility 1978
01922 Guided Missile Autonavigator Facility 1973
01923 Electric Power Station Building 1973
01925 Guided Missile Autonavigator Facility 1973
01929 Storage, Rocket Check Out/Assembly 1973
01938 Storage, Rocket Check Out/Assembly 1973



The Integrated Fire Control (IFC) area was connected to commercial power whenever practical, with converters to 400 hertz (cycles per second). This saved fuel, wear and tear and maintenance on generators and personnel. Most commercial power is 60 hertz (U.S.A) or 50 hertz (Europe). Special equipment is required to do this conversion - usually a 60 (or 50) hertz motor direct coupled to a 400 hertz generator. The Nike system was made as light as practical for easier transportability. Motors and transformers using 400 hertz (cycles per second) electricity are considerably lighter (need less iron) than similarly rated motors and transformers for 60 hertz. Also, 400 hertz is frequently used by the Army and Airforce in aircraft situations.

Bldg # Purpose Year Demolished
01950 Airport Surveillance Radar AN/GPN-20 Active, not part of D-Control  
01982 Electric Power Station Building 1973
01986 Concrete pad for Equipment Demolished, not part of D-Control  
01988 Storage, Rocket Check Out/Assembly 1972
01991 LMR Transceiver Site Active, not part of D-Control  
02601 Guided Missile Autonavigator Facility 1973
02604 Guided Missile Autonavigator Facility 1973
02607 Guided Missile Autonavigator Facility 1973
02611 Electric Power Station Building 1973
02613 Dining Hall, Airmen 1978
02614 Dormitory, Airmen 1978
02617 Dormitory Airmen 1978
02619 Unknown Unknown



The Integrated Fire Control (IFC) area had electrical generating equipment and fuel, in case of alert or local power failure. In the case of an alert, both the launcher area and IFC area started their generator, and switched over to this power. The commercial power was subject to a number of possible situations such as normal outages, attack damage, or intentional disruption.

With the Nike Ajax, there were had two gasoline engine driven 40 kW generators, and an operator to watch them. A 40 KW generator fits well into a two wheel trailer, and is a little larger than the usual search light generator you see at store openings. An engine working at 40 horse power easily runs a generator running at 40 KW, even allowing for the usual generation losses. The Nike Hercules HIPAR radar and associated equipment increased the power requirement and those sites had larger generators enclosed in buildings.

The Integrated Fire Control (IFC) area had telephones and radios for communication with other site areas. There was a necessary link with the launcher area that provided the following necessary information:

  • Alert status to launcher area
  • Which Missile selected, from launcher area to missile tracking radar for automatic slew to next missile
  • Azimuth Angle of predicted intercept point from computer to missile gyro

Launch (FIRE) command from FIRE switch, various safety interlocks, computer generated 2 second delay (for gyro settle) to launcher area.

These signals were normally transmitted automatically through the signal cable to the launcher area. In case of a cable fault, the signals could also be transmitted by voice radio and manually entered in at the launcher area. The missile selected could also be voice transmitted from launcher area to the IFC area and the missile tracking operator. Phone links to the administration area were useful for arranging transportation of relief crews and other day to day requirements.

The Integrated Fire Control (IFC) area had communication equipment for communication with tactical headquarters. Later there was sophisticated and effective control using: Missile Master, then BIRDIE and Missile Monitor by Tactical Headquarters.

The Army ADA batteries were always under the command and control of the Air Force by several means. Then came the Army command and control from the Army Air Defense Command Post (AADCP) at the battalion level. Communications may be lost with the Air Force but the battalion still had control of the site.

During the time of an air battle, a pilot could loose or forget to activate his IFF equipment. If so, there was only one safe way to return to any air base in any area. That was through the SAC-EWO safe corridors. The Strategic Air Command had predefined safe corridors back to any Air Base if the aircraft was having IFF or other problems. These corridors were zigzag lines (not straight lines) that the pilot had to follow and he had to be at certain altitudes at any given range to the air base. These safe corridors were marked on the PPI scopes in the fire control vans of HAWK and NIKE batteries. As long as an aircraft was in the corridor and heading in or out and at the proper altitude for the range he was at, he was safe without squawking the proper IFF code or no code at all. If there was an air battle going on at the time, most stray aircraft coming into range of a HAWK or NIKE battery would have been taken out, just because.

In Alaska the Air Force interceptors would have engaged any low flying aircraft. High flying bomber formations were at the pleasure of the NIKE batteries. The unofficial motto of ADA was to "shoot them all down and sort them out on the ground" and then send out letters of apologies.

The Integrated Fire Control (IFC) area had one or more surveillance radars for target identification. These are also called "acquisition" radars. In the original Nike Ajax sites, there was what is now called the LOPAR (for LOw Power Acquisition Radar) acquisition radar with a maximum display range of 100,000 yards or 56.8 miles. This was a "normal" magnetron pulse radar with a switchable moving target indicator (MTI) option.

Hercules sites (with the much longer missile range) needed a much longer-range surveillance radar. Two general types of longer-range surveillance radars were supplied:

1. the very large HIPAR radar that had a large control building. There was very sophisticated pulse generation, and multi-channel receivers with unique moving target indicators (MTI) and great deal of anti-jamming capability.

2. or a less sophisticated "Alternate Battery Acquisition Radar" (ABAR) radar usually either AN/FPS-69,-71 or -75.

The Integrated Fire Control (IFC) area had radar(s) for target tracking (one target at a time). The BC van and RC van were inside the admin building and all the antennas were inside air inflated radomes with individual blowers.

The Nike Hercules used two Target Tracking Radars. One radar tracked the target in azimuth and elevation, in "X" (3 cm) band. The other radar (Target Ranging Radar) tracked the target in range, in several radar bands. Range jamming is easier than angle jamming, so great attention was paid to counter-acting the range jamming including band switching, very agile frequency changing, pulse blanking, and pulse repetition rate changing.

(D Control Radar Tower on South Mountain)



If present, the non-mobile HIPAR Surveillance radar always was on a tower, it was apparently part of the equipment. If the tower is a bare concrete pylon surrounded by an outer steel skeleton (square in plan view if you were looking straight down on the tower), then it''s an early tracking radar tower.

The Integrated Fire Control (IFC) area had a computer to aid target selection, aid launch timing, send missile commands. This computer received tracking inputs from the target and missile radars and provided the following:

  • During pre-launch, while tracking the target, a Predicted Intercept Point and a Predicted Time of Flight was presented on plotting boards to the Battery Commander. This was based upon an assumed straight line flight. It was up to the Battery Commander to try to evaluate what the target would really do, and decide when and if to FIRE (launch a missile).
  • After launch, all of the above were continuously updated for the Battery Commander, and the computer also sent guidance commands to the missile via the Missile Tracking Radar.
  • The missile burst command, also via the Missile Tracking Radar.


The computer technology was "analog" instead of the digital technology, which was quite primitive and unreliable at that time.

The battery commander sat in the Battery Control van with:

  • the acquisition operator(s)
  • the computer and plotting boards, surveillance radar displays including the Identification Friend or Foe (IFF)

And was in direct communications contact with:

  • the target tracking operator(s)
  • the missile tracking operator
  • the Launch Control Officer(s) in the launcher section(s)
  • Tactical Headquarters

and operated the "FIRE" switch to control if and when to launch a missile

The missile tracking radar physically and electrically resembled the target tracking radar except for the dual transmit pulse capability. The missile tracking radar also transmitted the missile commands.

The Nike Hercules systems had two Target Tracking Radars that were externally similar. Internal differences included using different frequency bands. The two radars were used instead of the usual one radar to help fight enemy jamming. A variety of strategies made the life of enemy jammers extremely difficult. (The Nike Ajax systems had one target tracking radar).

One of the many keys to precision tracking between the target and missile tracking radars is the fact that (small) identical errors of tracking by both the target and missile tracking radars "cancel out". Example, if both the target and missile tracking radars say that their respective tracks are both 100 yards higher than absolute height, the actual miss distance (if every thing else was perfect) would be 0 yards.

This way, errors due to radar wave (like light wave) refraction in the atmosphere cancel out if both radars are tracking the same point in space (in this discussion we ignore the slightly different paths due to the slightly different physical location of the two radar.

Since the Nike Hercules had an "effective" range more than 3 times the Ajax, and a real range more than 4 times the Ajax, errors due to wind buffeting and similar errors could be 3 or 4 times larger, and possibly render Hercules ineffective (too inaccurate) at longer ranges.

To counter the wind buffeting, the tracking radars were enclosed in an air inflated fabric "bubble". This greatly reduced the wind forces on the tracking antennas. Even if the wind gust shifted the bubble a few inches, the air forces on the antennas would be greatly reduced during the shift of the "bubble". The "bubble" also protected the antenna from much of the differential heating due to the sun heating (expanding) one side of the mount and antenna relative to the other side (shady side) of the mount and antenna. Although both tracking antennas would likely be illuminated by the sun the same way, vertical alignment was usually made by one person at slightly different times (an error source) and one was never confident that everything was identical anyway.

The Integrated Fire Control (IFC) area had a radar alignment system for "bore sighting" the tracking radars. This was located about 200 yards away from the tracking antennas. The system included, a cable for remote control and power, a tall mast with supporting lines, a control box (1''x1.5''x1.5'') mounted on the mast, a waveguide up the mast, a little horn antenna and cross arm optical targets on the top of the mast. This was used primarily for boresighting the tracking radars. There was also provision for testing the radar receiving sensitivity.

The IFC Battery Control is where the Battery Commander and the Acquisition Operator sat. This was the central command place of the battery. Summations of the status of other places of the battery arrived here, and commands to battery components went out from here.

Expanded view of Battery Control Trailer





This is a diagram of the work place. The battery switchboard is just to the right, and the computer cabinets are to the right rear.

1. Plotting board, thin paper & ink, largest ring is 200,000 yds (over 110 miles)
2. T1 quick disconnect (T1 was a van that generated simulated aircraft echos and ECM interference for training purposes)
3. IFF (Identification Friend or Foe) control panel (the latest version with the Siemens IFF/SIF)
4. ACQ control panels - control the LOPAR radar
5. HIPAR control panel - control the HIPAR radar
6. Precision Indicator (PI) - (expanded view of the PPI -about 22 degrees wide 10,000 long)
7. Target Designator Panel - paints a ring and azimuth line to indicate designated target to Target Tracking operators - they see the same PPI picture)
8. Plan Position Indicator (PPI) ("radar scope") - also sent by the Target Tracking operators in the Radar Control van
9. Tactical control indicator
10. BCC indicator panel
11. Vertical plotting board 200 kyds / 100 kft
12. Status indicator lights, (White, Yellow, Red, Blue)
13. Target detected speaker (to help arouse sleepy operator)

The Integrated Fire Control (IFC) area had a computer to aid target selection, aid launch timing, send missile commands. This computer received tracking inputs from the target and missile radars and provided the following:

  • During pre-launch, while tracking the target, a Predicted Intercept Point and a Predicted Time of Flight was presented on plotting boards to the Battery Commander. This was based upon an assumed straight line flight. It was up to the Battery Commander to try to evaluate what the target would really do, and decide when and if to FIRE (launch a missile).
  • After launch, all of the above were continuously updated for the Battery Commander, and the computer also sent guidance commands to the missile via the Missile Tracking Radar.
  • The missile burst command, also via the Missile Tracking Radar.

The computer technology was "analog" instead of the digital technology, which was quite primitive and unreliable at that time. In the 1950''s, digital computers had tens of thousands of vacuum tubes, and because the vacuum tubes had a mean time to failure of only a few thousand hours, the computers had a mean time to failure of only a few hours. 90 percent "up" time was considered outstanding, and required a round the clock staff of real experts. Digital input and output devices were similarly failure prone. (In the 1970s, when reliable transistors and integrated circuits, and cheaper high speed memory became available, some Nike analog computers were replaced by digital computers.)

The only alternative that was reliable enough and accurate enough was the electronic analog computer, which could be implemented for the Nike with fewer than 500 vacuum tubes. There were failures, but the technology was maturing, the tubes were run in a different (not ON/OFF) manner, and the uptime exceeded 99% at most sites. (One failure a month was considered really poor.)



  • Left rack has the power supplies - outputs about 7 different voltages. Top panel is switches, meters, voltage warning lights. (Note: in the van installation, this rack is on the right side of the computer.)
  • Middle two racks - operational amplifies, brown square boxes are zero set units, back part of both racks have many relays
  • Right rack has the servo-driven potentiometers. Top panel has tracking radar offsets, test switches (sets test inputs, verify outputs)

The Nike Computer had 4 main missions:

  • Provide Predicted Intercept Point and Predicted Flight Time to Plotting Board - for human viewing
  • Provide Predicted Intercept azimuth angle to missile during pre-launch
  • Provide Missile Steering commands after launch
  • Provide Missile Burst command at correct time after launch

And of course be highly reliable, accurate, testable and maintainable.

The Predicted Intercept Point is the point where the missile would intercept the aircraft if:

  • the aircraft continued in a straight path and at the same speed
  • the missile was fired right now
  • and the Predicted Flight Time is the time from now for that meeting.

Before launch, this information is useful for the human decision making about when to fire a missile. After launch, this information is continuously updated based upon actual aircraft flight and missile position and flight characteristics.

The Predicted Intercept Azimuth is the direction from the launcher to the current Predicted Intercept Point. This direction (azimuth) was sent to the gyro in the selected missile before launch, and was used to provide the missile a sense of "down". This missile gyro and the missile control system kept the belly of the missile "down" and provided the computer and missile a common sense of "down" and left/right.

During missile flight, the computer sends Steering Commands to the missile (via the missile tracking radar) to guide the missile to the continuously updated Predicted Intercept Point.

The Missile Burst Command is generated by the computer since:

  • A human is much to slow and variable to send the command. Since the missile is traveling at about 3000 feet per second, a 0.1 second mistake means a missile explosion 300 feet from the intended location (a clear miss).
  • Nike missiles did not "see" the intended target, and could not generate their own burst command. (Although they would automatically burst if they did not receive steering commands for 2 seconds.)

The Missile Burst Command is sent via the missile tracking radar.

The missile is launched (essentially) straight up, boosted to about mach 1.7 in 3.4 seconds. It then turns its belly toward the calculated Predicted Intercept (allow 1 second). A sustainer rocket starts to increase the speed to mach 3.5. A full dive command (7 g''s) is sent to the missile to dive it from vertical toward horizontal to intercept the flight path of the target. When the missile has reached a vertical angle that will be a good flight path to the intercept point, the full dive command is removed and normal steering begins.

The predicted intercept point is constantly being updated by the computer from data from the target tracking radar and the missile tracking radar. Using the missile position from the Missile Tracking Radar, missile velocity and attitude generated in the computer, and the Predicted Intercept Point, the computer generates analog steering commands in gravity units (g''s) for the missile. These commands are sent to the Missile Tracking Radar, where the analog commands are converted into radar pulse sequences indicating the command to the missile.

About 0.1 seconds before the missile will be closest to the target, a missile burst command is send by a coded pulse sequence to the missile by the missile tra cking radar. This burst command is decoded and the missile warhead exploded. The goal is to explode the missile just before (10 meters) the missile would impact (or be at the closest point with) the aircraft. This way, the expanding blast of fragments goes through the space where the target aircraft would be - giving maximum damage even if a near miss.

LAUNCH SITE

At Thule the launch areas designated as A, B, C, and D launch were located at Dundas, North and South mountains. The mission of the Launcher area was:

  • Preparing and maintaining the missiles for flight
  • Elevating missiles to surface for launch
  • Selecting which launcher and missile for next launch
  • Erecting and Launching missiles
  • Keeping the missile launching equipment filled with ready missiles during alerts.

Usually located 1000 to 6000 yards from the IFC (radar area) the Launcher Area must have line of sight to the IFC Missile Tracking Radar. The Launcher Area had to be far enough away from the Missile Tracking Radar so that the rapid ascent of the missile (25 g''s) did not exceed the slew rate and acceleration rate of the MTR. One to three miles was the usual separation distance. The standard length of IFC to Launcher area cable provided was 6,000 yards.

The Missile Tracking Radar (MTR) also had to have line of sight with (see) the erect missiles and the Launcher Area test mast. There was a mast about 15 feet high in the launcher area, usually attached to the Launch Control Trailer. This had a missile transponder (just like on the missile) so that the Missile Tracking Radar (MTR) could track this for test purposes, instead of requiring an erect missile. Various test instruments were used to verify that the MTR was in fact sending the specified signals such as correct pulse pair separation, test conditions "yaw" and "pitch" g''s and burst command. This allowed more precise checking, and of course reduced wear and tear on missiles during the frequent non-alert tests.

Nike radar waves travel basically straight lines. The MTR had to be locked-on (track) the missile before launch. Another limit that was rarely a bother was that the tracking radars could only depress (point below the horizon) about 10 degrees. The launcher area could not appear below that angle or special changes had to be made.

There was a big advantage of having the Launcher Area near to or adjacent to the Missile Assembly area. The continual transportation of missiles (especially Ajax missiles with their very reactive liquid fuels) between the assembly and launcher areas mandated their being as close as practical. This was usually no problem. And the Administrative Area was usually within easy walking distance. This eliminated transportation problem of the larger launcher/assembly crews to and from the mess hall and barracks.



TH-01

Bldg # Purpose Year Demolished
1500 Security Guard Tower 1997
1501 Dormitory, Airmen 1974
1503 Recreational, multipurpose 1974
1504 Dining Hall, Airmen 1974
1509 Officer Quarters 1974
1512 Vehicle Ops. Parking Shed 1982
1514 No record  
1520 Storage check out and assembly 1973
1525 Storage check out and assembly 1973
1540 Storage check out and assembly 1973
1560 Guided Missile Erector Enclosure 1997
1561 Guided Missile Erector Enclosure 1997
1562 Guided Missile Erector Enclosure 1997
1564 Hazardous Storage, Base 1973
1565 Shop Missile Assembly Sold to Greenland Home Rule 1977
1569 Shop Missile Assembly Sold to Greenland Home Rule 1977



As with the IFC, the Launcher Area was connected (when possible) with local commercial power - to save fuel and wear and tear of the generators and people. There was one converter for each group of 4 launchers.

The Launcher Area generators were quite large 60 hertz units to handle the underground hydraulic elevator(s). The launchers used 400 hertz power for the hydraulic pumps to raise the missiles to an erect (vertical) position.



TH-13

Bldg # Purpose Year Demolished
3100 Security Guard Tower 1986
3105 No Record  
3107 No Record  
3111 Dining Hall, Airmen 1983
3112 Administration Office 1986
3114 Dormitory, Airmen 1978
3115 Dormitory, Airmen 1986
3121 No record 1986
3125 Guided Missile Erector Enclosure 1986
3126 Guided Missile Erector Enclosure 1986
3128 Guided Missile Erector Enclosure 1986



The "magazine room" was square, 60 feet by 60 feet and was 10 feet high to the bottom of the beams that supported the ceiling. There were no supporting columns in that area. There was a 57 foot long missile elevator in the center of the room to permit missiles to be moved between the this under ground storage area and the launchers above ground. The elevator "pit" was 6.5 feet below the floor of this room. The little room marked "personnel room" was 6 feet by 10 feet and contained the Launching Section Control Cabinet.

A drawing of the underground facilities (showing Nike Ajax missiles).



A View From The Watch Tower





Each Launcher Section in a permanent site had an underground storage area, with access through

  • The missile elevator
  • A stairway with a blast resistant door on the top and bottom
  • Crew escape hatch, a squarish, concrete surface structure with a single horizontal counterweighted steel door

Ventilation Shaft in Foreground, Access Hatch is to the Left





TH-40

Bldg # Purpose Year Demolished
2800 Security Guard Tower 1997
2801 Hazardous Storage, Base 1973
2815 Dormitory, Airmen 1978
2816 Administration Office 1983
2817 Dining Hall, Airmen 1997
2818 Dormitory Airman Permanent Party 1997
2831 No record  
2834 No record  
2836 No record 1997
2837 Guided Missile Erector Enclosure 1997
2838 Guided Missile Erector Enclosure 1997
2839 Guided Missile Erector Enclosure 1997



The small protected room at the lower center of the drawing contained all of the controls for

  • Raising and lowering elevator
  • Selecting the missile to be launched
  • Raising and lowering the individual launchers manually
  • Firing a missile if the signal cable from the IFC failed (using inputs from voice radio)



The missile magazines had two elevators per magazine, which was almost certainly a response to the harsh climate, which would have precluded the use of satellite launchers on the surface. The magazines at Thule were unique. Type B Rising Star pits were employed only at Thule AFB in Greenland. They were 49 feet in length and 123 feet wide and held ten missiles.

NOTE
Type B Modified were Ajax pits converted to handle the Nike Hercules M-36 launcher. Rising Star pits were employed only at Thule AFB in Greenland. The magazines are about 30 feet below the ground. There is a pit below the floor of the magazine about 10 feet below the floor where the sump pump, air and cable conduits and elevator shaft and equipment are located.




This elevator connected the above ground launchers with the below ground magazine (place to store ammunition). It was about 45 feet long and 8 feet wide (the booster fins were at an angle like an ''X'' so did not require full span width.) The elevator was raised hydraulically (hydraulic fluid - like your car brakes) and took about 20 seconds in either direction. On raising, the elevator would over shoot about 2 inches to allow 4 iron bars to slide into holes in the elevator door, then the elevator would gently settle down into a locked position. There were 2 long elevator doors that were normally closed when the elevator was down. The locking bars support the elevator for firing. Without the elevator being on locking bars, upon firing the downward thrust of the rocket cluster would drive the elevator and missile downward overcoming the hydraulic pressure that raised it initially."

Some people think the launcher on the elevator, upon firing, places the magazine in some sort of jeopardy from fire and burning debris. There is always that possibility, but the risk is pretty minimal for the following reasons: When launcher #1 is raised to its near vertical firing position, the nozzle ends of the rocket motor cluster are not positioned directly above the elevator but are actually positioned above the blast deflector behind and off the elevator. With the extremely large thrust generated at the moment of firing, the missile, and its trail of flame, is not near the elevator for more than a split second. Remember, this missile goes off like a bottle rocket, not like the space shots we see on TV where the rocket seems to burn on the launcher for a long time before it begins to rise slowly off the pad."

There was a launcher on the elevator, and missiles could be launched from it. Missiles were normally raised and lowered in a horizontal position. During alerts, after launcher 1 (on the elevator) was fired, the section leader and crewman 3 and 4 would come out into the magazine and:

1. Turn on the blowers
2. Set the elevator in console position
3. Tell the fire panel operator to lower launcher 1 and the launcher would start to lower and the elevator would come down at the same time
4. when the elevator got down, the doors would close
5. you would load another missile onto the launcher by rolling the empty launching rail to one side and rolling a loaded launching rail onto the launcher
6. hook it up
7. tell the fire panel operator to raise launcher 1 and the doors would open and the elevator and launcher would start up and the launcher would raise at the same time

The Fire Panel was in two pieces, the top was called the SCI (Section Control Indicator) and the bottom SSG (Section Simulator Group). On the SCI left side is where the 4 keys to complete the firing circuit were inserted.

The sites with underground magazines did have earthen berms surrounding their fueling areas. This was where the early Nike Ajax missiles were fueled, a potentially hazardous operation. Later, with Nike Hercules, a warheading building was installed within this area and the warheads were removed from their "cans" and attached to the missiles inside of this structure.

Security Outpost



The Nike Hercules missile launcher was called the M-36E1 monorail launcher. It often had rack sections attached to it also. The M-36E1 was a steel rectangle with electric and hydraulic components and a large erecting beam supported by movable supports. It was quite a bit bigger than the Nike Ajax launcher and weighed about 7 tons. "

Some Nike units were never employed in fixed or semi-fixed positions, and were used exclusively in their mobile role. So, how did this affect the launcher? All launchers had the capability of being moved and then set up to fire at another place. To do this, the 7-ton launcher would be fitted out with an axle, driving lights, brakes, towing pintle, outriggers and a portable blast deflector, and it would be towed behind a 5-ton truck as a "trailer" and driven to its field firing position. It would be placed on the ground, outriggers extended, storage and handling rails attached, and the ready missile transporter would off-load a missile onto it. From there on, the firing procedures would be about the same as the semi-fixed position''s procedures. The TO&E (Table of organization and equipment) called for all Nike firing batteries to have the trucks, axles and other equipment to make the launcher "portable"; however, most units in the semi-fixed positions around the defense areas operated on a MTO&E (modified table of organization and equipment) that excluded the axles, etc., ... "

Rate of fire

One method was to bring the first missile up on the elevator launcher (launcher #1) and fire it from the launcher #1. Then lower the elevator to the magazine, get the second missile, take it up and fire it from the launcher #1. You could repeat this process six times until all missiles in the magazine were fired. Your rate of fire is limited in this process by the speed by which you could move the missile (below ground) onto the elevator, raise the elevator (34 seconds) and fire. " Regardless of the method used, keep in mind several facts. The actual firing generated considerable noise and flame, but the effects of firing last but a split second. Some minor damage to the launcher may occur (paint burned or a cable singed) but usually you can fire again about as fast as you can reload the launcher and have the missile tracking radar return to lock onto the second missile. Also remember that the other section or sections have their missiles ready to fire, so you can skip from section to section within the battery thereby giving any section a few more minutes to prepare the launcher to fire again.



THO-60

Bldg # Purpose Year Demolished
2000 Security Guard Tower Inactive /Not demolished
2002 Dining Hall, Airmen 1974
2004 Dormitory, Airmen 1974
2007 Vehicle Ops parking Shed 1974
2009 Electric Power Station Building 1974
2011 Storage Ammunition 1969
2023 Dormitory, Airmen 1973
2041 Electric Power Station Building 1974
2044 Guided Missile Erector Enclosure Inactive /Not demolished
2045 Guided Missile Erector Enclosure Inactive /Not demolished
2046 Guided Missile Erector Enclosure Inactive /Not demolished
2051 Hazardous Storage, Base 1973
2054 Hazardous Storage, Base No Record



HERCULES, THE MISSILE

The first successful test firing of a Nike missile occurred during 1951. This first Nike missile was later given the name Nike "Ajax". Nike Ajax was a slender, two-stage guided missile powered by a liquid-fueled motor utilizing a combination of inhibited red fuming nitric acid (IRFNA), unsymmetrical dimethyl hydrazine (UDMH) and JP-4 jet petroleum. The Ajax was blasted off of its launcher by means of a jettisonable solid fuel rocket booster, which fired for about 3 seconds, accelerating the missile with a power of 25 times the force of gravity.

The Ajax missile was capable of maximum speeds of over 1,600-mph and could reach targets at altitudes of up to 70,000 feet. Its range was only about 25 miles, which was too short to make it a truly effective air defense weapon in the eyes of its many detractors. Its supporters countered that the new missile was markedly superior to conventional antiaircraft artillery, and that it was, significantly, the only air defense missile actually deployed and operational at that time.

Work on a successor to the first Nike missile, the Nike "Ajax", was initiated well before the first Ajax missiles were deployed at sites across the nation. Two primary considerations drove the development of this second-generation Nike missile. The first involved the need to field a missile with improved capabilities to defend against a new generation of faster and smaller targets, including supersonic aircraft and tactical ballistic missiles. The second was the desire to arm this new missile with a powerful atomic warhead.

Originally designated as "Nike B", the Nike "Hercules" -- as this missile was later known - was a far more capable missile than its predecessor (the Nike Ajax) in nearly every way. With a maximum range of about 90 miles, maximum speeds of over 3,200 mph, and the ability to reach targets at altitudes in excess of 100,000 feet, the Nike Hercules was a very potent air defense weapon. The Hercules missile lacked most of the complex, miniaturized vacuum tubes utilized by the Ajax, and employed solid rocket fuel in its "sustainer" motor which made it easier and safer to manage than the Ajax which employed highly caustic liquid fuel components.

Unlike the Ajax, the Hercules was designed from the outset to carry a nuclear warhead. Designated "W-31" the Hercules nuclear warhead was available in three different yields: low (2-Kilotons); medium (20-Kt.) and high (30-Kt.). For purposes of comparison, the atomic bomb dropped on Hiroshima, Japan, near the end of the Second World War had a yield of approximately 12 Kilotons.

Armed with its nuclear warhead a single Nike Hercules missile was capable of destroying a closely spaced formation of several attacking aircraft. This warhead enabled the Hercules to destroy not only the aircraft, but also any nuclear weapons they carried, preventing them from being detonated. Some of the first Hercules missiles deployed in the United States were initially equipped with the "W-7" nuclear warhead.

The Hercules could also be equipped with a powerful, high-explosive, fragmentation-type warhead designated "T-45". The warhead provided a useful alternative to the W-31 (particularly for use against a single aircraft and for low altitude use in proximity to populated areas) and was deployed at many overseas sites. Additional warhead designs, including "cluster" type warheads containing numerous submunitions, were developed although not deployed operationally on the Nike Hercules missile.

More sophisticated radar and guidance systems were also part of the Hercules "package". These made the Hercules system more accurate and effective at longer ranges. During the early sixties, an "improved" version of the Hercules system, utilizing ABAR (Alternate Battery Acquisition Radar) or HIPAR (High Power Acquisition Radar) was deployed. The improved radar capabilities and other advanced electronic features of the Improved Hercules system made it more effective against small supersonic targets including aircraft, aircraft launched "stand-off" missiles, and tactical ballistic missiles.

An relatively unknown fact is that the Hercules missile could also be used in a surface-to-surface mode. In this role, Hercules would have been used to deliver "tactical" nuclear warheads to destroy concentrations of enemy troops and armored vehicles, or bridges, dams and other significant targets from bases and field deployments located primarily within Western Europe. This surface capability might also have proven useful in other areas where the Hercules missile was deployed including South Korea, Taiwan, and Turkey. Maximum range of the Hercules missile in the surface-to-surface mode was slightly over 110 miles, and was limited by the effective transmission range of the Missile Tracking Radar (MTR).

The Department of Defense formally identifies the Nike missiles as:

Nike Ajax (with a range of about 25 miles) as MIM-3A Nike Hercules (with a range of over 75 miles) as MIM-14A and MIM-14B The NIKE missile sites at Thule AB utilized the NIKE Hercules.

A photo of a Nike Hercules on partially raised launcher

Key to numbers:

1. Radar windows (4 of them), received from and transmitted to the Missile Tracking Radar (MTR)
2. Missile wings (4 of them)
3. Steering fins (4 of them)
4. Coupling between booster and missile
5. Booster fins (4 of them)
6. Launching rail, has wheels for moving missile on rails
7. Erecting rail,
8. Erecting levers, driven by hydraulic cylinders

Please Note: the missile is resting on the launching rail with its fins (or wings) on either side of the launching rail. The side of the missile resting on the launching rail is called the &quo t;belly" or bottom of the missile. This part or the missile is "down" (toward the center of the earth) when the missile is flying toward the target.

Nike Hercules Missile Data

Designation MIM-14
Length (incl. booster) 41-feet 6-inches
Length (w/o booster) 7 feet 0-inches
Wingspan 6-feet 2-inches
Diameter of Body 2-feet 6-inches
Firing Weight 10,560-pounds
Weight w/o booster 5,250-pounds
Max. Speed at Burnout Mach 3.5 (2,597-mph)
Maximum Slant Range 75-90 miles (air defense) 110+ miles (surface mode)
Operational Ceiling 100,000-feet (later, 150,000-feet)
Booster Cluster of 4 Ajax-type solid propellant boosters
Sustainer Solid-propellant rocket motor
Warheads Nuclear warhead type "W31"

  • 2 Kilotons (low yield)
  • 20 Kt. (medium yield)
  • 30-40 Kt. (high yield)

conventional, high explosive, fragmentation type "T-45" warhead Guidance Command guidance system; missile guided by ground-based radar & computer system

The Nike Hercules had a variety of warheads both nuclear and conventional explosives. The T-45 conventional high explosive warhead weighed 1106 pounds and contained 600 pounds of HBX-6 military explosive. The Nike missile warhead section (M-22, M-23 or M-97) was an integral part of the Nike missile. Nike Hercules used the W-31 warhead weighing 1123 lb. Yield was switchable between 2 or 40 kiloton. They were after detonated after launch by either:

Burst command from Battery Commander
Burst command from computer 2 seconds after loss of Missile Tracking Radar tracking signal
To keep the warhead from exploding near the ground, and causing high levels of ground radioactivity, a "Barometric Probe" was used. The probe is a part of the warhead system and was used to sense the barometric pressure (as opposed to dynamic pressure) at altitude.

This pressure sensing was then sent to the barometric switches (baro switches) in the warhead where they served to "advise" the warhead circuitry of the missile altitude. This information was used by the warhead to complete warhead arming sequences and to provide altitude warning in the fail-safe system to provide a "one point" or HE detonation as required by a missile returning to low altitude with no direct fail-safe signal received from the MTR. The baro switches were set at the time of mating the warhead to the missile (this was done by use of the T 4014 Test Set in the Warhead Building) and could also be set at the launch area after mating.

There were two altitude settings - high and low - arming sequence and fail-safe sequence settings. The baro probe was a delicate mechanism and was always part of the Technical Proficiency Inspection as relates to the unpacking (they came in steel containers), cleaning, and mounting. It was carefully inspected for freedom of movement and cleanliness.

Nike missiles need electric power to operate the radio (Transponder) and decoder electronics. The power requirements were slightly higher because the transistor was not yet a rugged reliable device and tubes were used for all electronic amplification. It also had to power the hydraulic servo valves and the detonation of the explosive bombs. (The steering fin movements were powered by the hydraulic accumulator.) The Nike Ajax used a 28 volt silver-cadmium battery with potassium hydroxide as the electrolyte. This is a close relative of Edison''s nickel-cadmium battery used in the Nike Hercules but with a little higher energy per weight. The battery was not charged during flight, it just supplied power. The physical size of the Ajax battery was similar to a motorcycle battery - about 6 inches by 4 inches by 4 inches. The Hercules battery was considerably larger due to higher power consumption and longer flight time.

The Missile Tracking Radar sent pairs of radar pulses separated by say 2.3 microseconds to the missile. This helped the missile distinguish pulses from the MTR (Missile Tracking Radar). Also each site in an area used a different pulse separation so the missile will listen to only its own MTR.

The Nike missile had 4 microwave windows or antennas facing backward and a little to the side. Each antenna was 1 inch diameter and was able to pass 3 cm wavelength microwaves into and out of the missile. Antennas 2 and 4 were connected to the missile receivers. Antennas 1 and 3 were connected to the missile magnetron, which was fired when the missile receiver received a correct pulse pair from the MTR. The missile''s magnetron generated a peak power of 320 watts from the feedhorns.

When the missile receiver detected a pulse separated from the preceding pulse by the correct time interval (an example could be 2.3 microseconds) the missile receiver signaled the missile transmitter to send a pulse back to the MTR. The MTR actually tracked the missile transmitted pulse, not the (much weaker) MTR pulses reflected back from the skin of the missile. The combination of receiver and transmitter operated in this fashion is called a Transponder.

The computer sent steering commands to MTR, which converted the commands to tones. The voltage from the tones controlled the rate that the pulse pairs are transmitted. A higher voltage gave a higher rate of pulse pairs transmitted. The missile ''listened'' for the rate of the pulse pairs, and detected the tones, which controlled the MTR. These tones contained the steering and burst commands. These tones were then or decoded and sent to the steering and warhead sections.

The Steering (or "Guidance") section was responsible for accepting the steering commands, and causing the missile fins to move in a way to follow the steering commands. It also caused the missile to roll to keep its ''belly'' downward as indicated by the onboard gyroscope. The steering commands were sent from the computer via the MTR as ''g''s. 1 ''g'' is the ''force of gravity'' at the earth''s surface.

There is more to steering than meets the eye. Remember when you started to drive a car - you had no idea

1) what direction the wheels were pointed when you started
2) how much to turn the wheel to cause the car to go quickly (but not too quickly), and with out overshoot into the desired direction. For a while you either understeered (did not move the wheel enough) or oversteered (moved the wheel too much). In servo terms, you soon learned how much to turn the wheel for a given desired correction (gain adjustment).
3) how to keep the car from swerving back and forth about the desired direction until you learned to steer less hard as the car approached the desired direction (damping adjustment).
4) you had to turn the wheel less at higher speeds or you skidded or threatened to roll the car.
The car did not behave well, your friends got a chance to laugh - until they also had trouble. But you quickly learned to steer reasonably well.

Similar type of steering control problems exist with most steering problems (boats, torpedoes, missiles, etc.) and must be corrected. The command decoder in the missile gives the g''s requested by the computer. To provide good steering without "hunting" back and forth, other conditions are sensed:

accelerometers tells the guidance system what ''g''s the missile is doing right now. potentiometers indicates the current direction of the fins rate gyros indicate rate of change in missile attitude static pressure and ram air pressure tell how high and fast the missile is flying. This changes the servo gain to provide good control at different altitudes and speeds These sensed conditions help provide smooth steering.

The steering fins were at 45 degrees from "down" and the steering commands were similarly not up/down but up_left/down_right. This unexpected flying attitude permitted all of the wings to help the missi le dive strongly (decreasing the ''dead zone'') with out stressing the wings too much. There were two sets of steering controls, one for up_left and one for up_right. This included two accelerometers (oriented the 45 degrees from "down"). The accelerometers were little black boxes about 2x2x3 inches. They were suprisingly heavy, due to the large magnets inside to provide magnetic damping.

Another function of the steering (guidance) was to roll keep the belly down so that the radars, computer, and missile had a common frame of reference. An on-board gyroscope provided the reference for the missile. The down direction was the same for radars, computer, and the missile.

The missile belly was kept in a plane that included:

the missile itself
the center of the earth (really down)
To help keep the gyro from approaching the "gimbal limits" and "tumbling" the angle of the predicted point of intercept was sent to the gyro just before launch. The "spin axis" of the gyro was set perpendicular to this predicted point of intercept direction. The Nike can go about plus/minus 70 degrees azimuth from the predicted intercept point at launch time before its gyro loses its sense of direction.

During the boost phase, the steering or guidance section keeps the missile going in a straight line and not rolling. The missile starts to roll to put its belly toward the predicted intercept point and down at booster separation.

The Nike steering fin movements were powered by an ''hydraulic accumulator''. This ''accumulator'' stored several quarts of hydraulic fluid at a pressure of about 2000 pounds per square inch. The hydraulic fluid was controlled by small slide valves that did not take much energy. The hydraulic fluid pushed pistons, which controlled the steering fin angles. A great deal of force was necessary to move the fins of the missile flying at supersonic speeds. The slide valves acted as power amplifiers.

FIRE IN THE HOLE!
ALERT - "BLAZING SKIES "
ALERT - "Blazing Skies " This is not a drill!

1) A VHF radio message arrives raising the alert status with the words "Blazing Skies" "this is not a drill"! ("Blazing Skies" is the code for "aggressor engagement")
- - Various sirens and horns are activated.
2) The troops hurry to assigned stations, and start the equipment (it may have been "OFF").
3) The backup generators are started, and Launcher and Radar areas are transferred to these.
4) There is time to re-check the daily checks and alignments. All looks good
5) The acquisition radar(s) energized. The Plan Position Indicator (PPI) radar sweep goes round and round
Battery Ready!
6) The battery commander requests status of all sections, reports "READY" to Area Control.-- The Captain inserts the FIRE key into the safety lock, permitting a missile launch command
- - The Captain sets the site status to "RED" alert
7) There are reports of fighter plane actions out of range of the radars.
8) The acquisition radar operators see planes with "friendly" IFF (Identification Friend or Foe) flying toward battle
9) Area Control starts warning of approaching enemy aircraft. Two aircraft with out "friendly" IFF are seen at the most distant range of site acquisition radars
- - These are assigned names "Track #2" and "Track #3" by Area Control.
10) Area Control assigns "Track #2" to this battery. ("Track #3 is assigned to another battery)
11) The Launch Control Officer selects a missile for launching, the Missile Tracking Radar locks onto it. (Usually the Launch Control Officer selects the missile on the elevator if it is ready. When fired, this launcher can be quickly reloaded by lowering, re-loading, and raising the elevator. This permits a high rate of fire for all of the missiles.)
12) Suddenly the PPI radar scope bursts with bright streaks, the "Track #2" is hidden in one of them
13) A hurried toggling of anti-jamming switches shows hints of the "Track #2" in the now dimmer streaks.
14) The battery commander assigns "Track #2" to the target tracking radar.
Tracking assigned target!
16) The Target Tracking Radar is LOCKED on to "Track #2", the proper light lights.
17) TTR operators report using AIDED MANUAL because of some jamming in their radar scopes.
18) The computer operator reports computer settled, and the plotting boards and meters show:
- - Target position, altitude and ground speed.
- - Where the missile would intercept the target if launched now, and the target continues this speed and direction
- - The time necessary for the missile to fly to this Predicted Point of Intercept.
19) (At present, the Predicted Point of Intercept is just out of effective missile range)
- - As the target is going fast (mach 1.7) the predicted intercept point is far ahead of the target
20) The Battery Commander waits until Predicted Point of Intercept is within range,
- - feels sure that the lack of IFF means the plane is really the enemy, not a friendly with an equipment fault
- - verifies that the target is not in any Strategic Air Command SAC-EWO safe corridor and not at the safe altitude
- - and feels reasonable confident the plane will not turn around, wasting a Nike shot.
Launch missile!
16) FIRE - the Captain has lifted the RED switch cover and operated the FIRE switch!
- - the missile is launched, no extra sound heard in the Battery Control van.
- - the missile will be "boosted" straight up for 3.4 seconds, gaining speed rapidly.
- - the target is currently 61 miles away & 6.2 miles high, the Predicted Point of Intercept is 41 miles away
- - the predicted Time to Intercept is 65 seconds
22) The plotting pen that had been tracking the Predicted Point of Intercept now tracks the flying missile.
23) 5 seconds
- - the missile is 2 miles high, going about strait up, flying at Mach 2.6 (2,000 miles per hour)
- - the booster has dropped off, (the sustainer rocket motor will start in a few seconds
- - and has turned its bottom toward the Predicted Intercept Point
- - the computer commands the missile to started diving toward the Predicted Point of Intercept
- - (In the launcher area, the missile elevator is being lowered for reloading.)
24) As the target gets closer, we see it better as our radars "burn through" the jamming
25) 10 seconds
- - the missile is 4.4 miles high, 1.3 miles down range, flying at Mach 2.5 (1,875 miles per hour)
- - the computer (using missile tracking information) sends steering commands to missile
- - the sustainer rocket motor starts up, will burn for about 30 seconds
26) 20 seconds
- - the missile is flying at Mach 3.5 (2,625 miles per hour), toward Predicted Point of Intercept
- - about 7.3 miles high and 6.3 miles down range from the launcher
27) 30 seconds
- - the missile is flying at Mach 3.75 (2,815 miles per hour), toward Predicted Point of Intercept
- - about 8.5 miles high and 12 miles down range from the launcher
- - missile sustainer rocket motor has run out of fuel, missile coasting
28) 40 seconds
- - the missile is flying at Mach 3.5 (2,625 miles per hour), toward Predicted Point of Intercept
- - about 8.5 miles high and 20.2 miles down range from the launcher, missile coasting
- - "Track #5" (without IFF)) appears on the radar, and is assigned to this battery as next target
29) 50 seconds
- - the missile is flying at Mach 3.25 (2,435 miles per hour), toward Predicted Point of Intercept
- - about 7.75 miles high and 28.5 miles from the launcher, about 16 miles from "Track #2"
- - the target and missile are approaching head on, missile coasting
30) 60 seconds
- - the missile is flying at Mach 3.25 (2,435 miles per hour), toward Predicted Point of Intercept
- - about 6.7 miles high and 36.6 miles from the launcher, about 4.9 miles from "Track #2"
- - the target and missile are approaching head on, missile coasting
31) 64.6 seconds
- - the missile and target are both 40.15 miles from the launcher, 6.2 miles high
- - the missile explodes slightly above and 30 feet in front of target
- - explosion and metal fragments turn "Track #2" into unflyable wreck, a wing comes off.
32) 70 seconds
- - Missile tracking radar locked on next missile
- - The ground speed of "Track #2" drops to almost zero
- - Battery commander assigns "Track #5" to Target Tracking Radar
Another target and launch
33) 75 seconds
- - Missile tracking radar is still locked on next missile
- - Target tracking radar locking on new target "Track #5"
34) 80 seconds
- - Computer has settled with new target tracking information
- - Predicted Intercepted Point for "Track #5" is with in range
- - second missile launched, heading to "Track #5"
35) 120 seconds
-- Missile Elevator has been reloaded, raised, erected, and is ready for firing.

FLIGHT
Nike Pre-Launch Sequence

This sequence assumes that all of the daily, weekly, etc. checks have been performed. This information is grouped into the following sections:

  • Preparation Phase (under-ground)
    - Missile armed to operate at booster separation
    - Flag and plug removed from missile air speed (pitot) hole
    - Missile lifted by elevator to surface
  • Preparation Phase (above ground)
    - (optional) Missile moved to adjacent launcher
    - - Missile connected to gyro preset and booster igniter circuits
    - - Missile raised to vertical position (actually about 87 degrees)
    - - Missile Officer selects missile - may be one of many
    - - Missile Officer assures that missile launch key is inserted into Launch Control Console
  • Missile is ready to launch (fire)
    - (At IFC area)
    - - Missile Tracking Radar locks onto (tracks) missile
    - - Target is tracked
    - - Computer is "settled" - there is a predicted intercept point
    - - Azimuth angle of predicted intercept point is sent to missile gyro by computer. Note: missile gyro is used to tell missile guidance the direction of "down"
    - - Battery Control officer lifts protective cover from Launch Switch
    - - Battery Control officer operates Launch Switch
    - - Computer delays "Launch" order for 2 seconds to assure missile gyro has settled to angle of Predicted Intercept Point
    - - Electrical launch signal goes to launcher area. Electric signal goes through Launch Control Console (key enabled) to missile boosters
    - - Electric signal ignites missile boosters

Time 0 sec, Electric Signal Ignites Booster
The booster igniters (one for each of the four booster tubes) almost explode into large flames, which ignites the main "cruciform" shaped solid propellant (potassium perchlorate and a rubber compound?). In just a tenth of a second, full thrust is attained and the missile starts to move upward at an acceleration of 25 times the acceleration of gravity. (The acceleration of gravity is about 32 feet per second per second)

The missile guidance is active, keeping the missile vertical (0 g''s turning) and the bottom of the missile pointing in the same direction as at launch (no roll).

Time 3.4 sec, End of Booster, Start Roll then 7 g Dive



After 3.4 seconds, the missile is going straight up at 2000 miles per hour and is almost 1 mile high. The booster cluster has burned all its fuel (0 thrust). The booster cluster has more aerodynamic drag than the missile, and uncouples (the missile slides out of the cone shaped holder). The lanyard (a short cord connecting the missile from the booster) is pulled, pulling a pin from the missile. This pin operation closes an electric circuit informing the missile circuitry of booster separation. The following happens:

A roll maneuver is executed to bring the bottom the missile into the rotational plane of the gyro. This synchronizes "up/down" with the ground radar and the computer.

Either the sustainer motor is ignited, or an 8 second delay is started so that the upcoming 7 g dive will be performed and a lower speed and be smaller radius (decreasing the "dead zone" where the missile can''t reach)

The roll maneuver is allowed one second to complete then the computer and missile radar command the missile to "dive" at 7 g''s. This dive starts the missile toward the Predicted Intercept Point, since "down" for the vertical missile is in that direction.

The computer will continue sending this 7 g command until missile tracking shows that the missile is on a 0.5 g flight path to the Predicted Intercept Point. This path means that the missile will "fall" at an acceleration if 0.5 g s, and be supported by its fins by 0.5 g s (1/2 of the weight of the missile will be supported by the fins). This low weight on the fins decreases the missile drag, and the thin air of this high flight path will also decrease missile drag (keeping the speed high while decreasing the need for a larger sustainer motor).

The above paragraph means that 7 g dive is stopped a little early so the missile will make a shallow arc to the Predicted Intercept Point. If the Predicted Intercept Point is low and relatively near, the 7 g dive lasts longer. If the Predicted Intercept Point is high and relatively far, the 7 g dive lasts a shorted time.

The "Dead Zone" as a donut shaped area around the site that the missile is not capable of entering. This limit is because the missile is launched straight up, and has a maximum dive capability of 7 g''s due to fin strength limits. A method of decreasing the size of the dead zone is to cause the missile to go slower so that the turning radius is decreased. Delaying the start of the sustainer motor eliminates the normal missile speed increase during the 7 g (later 10 g) dive, decreasing the turning radius, and decreasing the size on the dead zone. This method is chosen when the predicted intercept point is close and low. The minimum dead zone using this method is about 21,000 ft high and about 4 miles in radius.

If the predicted intercept point is more than 10 miles away, or above 30,000 feet, the firing of the sustainer motor is not delayed and the missile starts gaining speed to mach 3.5 earlier in its flight. Nike sites were frequently patterned so that the dead zone of one site was in the firing or accessible zone of one or more other sites.

Determining when to end the 7 g dive



The above diagram shows three (of many) possible flight paths. The paths start from the missile''s 7 g dive and end at the Predicted Intercept Point.

The "0 g" flight path is not supported by any airlift on the wings of the missile. The missile basically acts like a bullet, falling freely due to the acceleration of gravity. A person riding on the missile would not feel any gravity, would feel "weightless".

The advantage of this flight path is minimum air friction (drag). The missile is at zero angle of attack (through the air) giving minimum friction. A side benefit is that the flight is high - through thinner air.

The disadvantages are:

1) Longer flight time
2) On high, distant targets, the missile could be above effective air so that it could not dive quickly if needed

The "1 g" flight path is fully supported by the missile wings. It is similar to driving an airplane straight from point a to point b. A person riding on the missile would feel normal gravity, would feel full weight. The advantage of this flight path is it is the straightest and may yield the shortest flight time. The disadvantage is that the missile flies through thick (dense) air yielding higher friction and shorter range

The "0.5 g" flight path is the flight path chosen for the Nike Ajax (and probably for the Nike Hercules). A person riding on the missile would feel 0.5 normal gravity, would feel one half weight. This path is a reasonable compromise between advantages and disadvantages of the options above.

The computer determines when to end the 7 g dive to enter the 0.5 g path, then steers the missile to follow this flight style.

Time (approx.) 12 sec, End 7 g dive, Start Cruise



At the end of the 7 g dive, normal steering commands are sent to the missile to send it to the constantly updated Predicted Intercept Point. The computer continues to accept tracking information from the Target Tracking Radar and the Missile Tracking Radar, uses a missile speed profile built into the computer, and updates the probable remaining flight time and Predicted Intercept Point.

Steering commands are as gentle as possible until the last 10 seconds to decrease steering caused drag, and thereby maintaining highest possible speed. The steering commands during the first part of the normal flight are decreased to allow for the following effects:

Normal target tracking of a weak signal (lots of electrical noise in relation to signal from the target) is by definition noisy, but not nearly as noisy as the following:

Tracking a jamming target can be quite noisy, operators changing tracking modes to fight jamming, the system occasionally locking onto chaff dropped by the target, etc.

The target aircraft itself may be wildly evading fighter planes, other missiles, trying to confuse tracking, struggling with air turbulence, etc.

The above conditions can cause large swings (as much as 15 degrees azimuth and 15 % range) in the Predicted Point of Impact, especially when there is a long time to Predicted Intercept.

Commanding the missile to steer hard for each wild change causes large g force commands, and the high "aerodynamic angle of attack" to produce the large g forces produce high drag. High drag reduces missile speed, causes longer flight time, and reduces range (all bad).

The reduced steering command scheme tends to average out the large swings, giving a faster flight. During the last 10 seconds of flight, full steering commands are sent.

Time (later), Burst Command



About 120 milliseconds before expected missile impact with (or closest approach to) the target at the Predicted Intercept Point, a "missile burst" command is issued by the computer through the Missile Tracking Radar. Some milliseconds are required for the missile to decode this command - then - oblivion - for the missile and hopefully the target.

Preparing for the Next launch

After the burst command is sent, the Missile Tracking Radar (MTR) automatically slews (moves rapidly) to the next designated missile in the launcher area. The MTR can "lock on" to this next missile with in 5 seconds. It probably takes the battery commander more than this 5 seconds to evaluate if the target has been disabled (see below). If the target has not been disabled, the next missile could be on its way to this target in another 2 seconds.

To help the battery commander to decide quickly if the target is disabled, there is a "Target Ground Speed" dial in front of him. If the target speed suddenly slows, and the target elevation suddenly drops, the battery commander may decide that the target has been disabled.

If the target appears disabled, a new target may be designated. This could be quite quick as there has been relative idle time during the missile flight for continued viewing and analysis of the defense area. Area control could well have designated the next target for this battery.

It will take the Target Tracking Radar maybe 10 seconds to slew to the next designated target, find the target in range and azimuth and elevation, and lock onto it. There is a PPI scope in the Radar control van showing the target-tracking operators the same picture that the battery commander sees. This shows both the target and the azimuth and range of the TTR. This aids target acquisition in azimuth and range. The elevation operator has fewer aids. He may have been given advisories from the acquisition radars or area control about the height of the target, such as "appears high", "on the deck", but the target search in elevation has no real mechanical aid. He searches up and down quickly trying to find a target at the correct range.

The computer will take probably another 5 seconds to "settle" and give predicted intercept point, and the battery commander needs time to analyze the situation with this next target before committing a missile to it.

CLOSURE
End Of The Nike Era


ARADCOM entered the 1970s with the same three-fold mission it had retained over the years. ARADCOM provided the Commander-in-Chief, North American Air Defense Command, with combat-ready air defense forces; support for Safeguard, with employment planning and advanced ballistic missile defense planning; and ADA units to the Commanding General, United States Continental Army Command, for employment in ground defense, civil disaster and other emergency missions. This action had been justified by the belief that these bases were more susceptible to attack by ICBM than to bombing attack. Subsequent cuts, however, had been undertaken almost purely as economical measures for which system analysts of the Office of the Secretary of Defense (OSD) had provided a rationale.

The major premises of that rationale were an assumption that the threat of Soviet bomber attack had decreased sharply, a conviction that the current air defense force was costly and ineffective, a belief that air defense of urban areas would be eliminated by initial ICBM attack, and faith in the concept of perimeter defense by USAF airborne warning and control systems (AWACS) and F-I 06 aircraft. To these there had been added in the FY70 Draft Presidential Memorandum the contention that any Nike Hercules units that might survive an ICBM attack would be ineffective in countering a follow-on, low-altitude bombing attack in which electronic countermeasures (ECM) were employed.

Although Nike was created in response to Russian efforts to design and deploy long-range bomber aircraft during the early years of the Cold War, Russian military strategy soon changed. Fearing that their manned aircraft would be too vulnerable to attack by supersonic American interceptor aircraft armed with rockets and missiles, the Russians decided to focus their attention on developing ICBMs -- Intercontinental Ballistic Missiles -- against which there existed no effective defense. As a result, the Russians never deployed a large and capable strategic bomber force comparable to the Strategic Air Command of the United States Air Force.

TThe shifting nature of the Soviet threat meant that the air defense role, for which Nike was originally intended, became relatively less critical as time passed. Defense dollars were needed for other projects (including the development of American ICBMs and potential missile defenses) and to fund the rapidly growing war in Vietnam.

ARADCOM held that most factual evidence supported contrary views. In spite of intelligence projections of declining Soviet bomber strength, the size of the threat had remained constant; ARADCOM forces, in fact, offered protection to a significant portion of the population and economic base at relatively small cost; destruction of a significant number of Nike Hercules units would be possible only if sufficient ICBMs were available to target each unit; a perimeter defense, technically premature at present (1973), would inevitably be porous and require to be backed by defense in depth; and test results showed that, far from being ineffective, Nike Hercules units provided a highly effective defense in the face of fairly heavy ECM and limited early warning. More-over, to eliminate the air defense of cities because of their vulnerability to missile attack would be to offer an attacker the option of employing bombers against little or no resistance.

Each year of the 1970s saw ARADCOM reduce the number of firing units and associated headquarters. Cuts that started in 1964 continued to the final ones in 1974. A first cut of 22 fire units, taken in 1964, had removed the Nike Hercules defenses of SAC bomber bases and Thule Air Base in Greenland. The 4th Battalion, 55th Artillery ceased operations during May 1965, ending the Nike missile defense of the Thule base. During 1974, all remaining sites within the nationwide Nike air defense system were inactivated. Army Air Defense Command (ARADCOM) which administered this system was closed down shortly thereafter. One of the nation''s most significant Cold War air defense programs had come to an end.

The story are from thuleforum.



Picture from thulebasen.dk