Description
Technical Manual (TM 9-1220-206-12) for M15 Gun Direction Computer February 1960
This Technical Manual TM 9-1220-206-12 covers the M15 Gun Direction Computer and is dated February 1960.
It provides operation and organizational maintenance guidance for an electromechanical analog computer used to calculate and transmit field-artillery firing data.
Historical Significance
The Army standardized the M15 in 1958 and began issuing it to field-artillery units in early 1960. It served as an interim step between manual firing charts and the transistorized M18 Field Artillery Digital Automatic Computer, better known as FADAC.
The M15 increased the speed and accuracy of technical fire direction by automating calculations previously performed with plotting boards, graphical firing tables, pencil, and paper. The M15 was configured for the 105 mm howitzer, while the related M15C was developed for the 155 mm howitzer.
The M15 and M35 Fire Control System
The M15 operated as part of the M35 Field Artillery Fire Control System. A typical system combined three M15 computers with an M1 Gunnery Officer's Console, power-conversion equipment, and a suitable generator so several computers could work independently or together under the gunnery officer's direction.
Using the coordinates of the target, weapon, and observer, the M15 calculated deflection, quadrant elevation, and fuze data. It then transmitted the resulting technical fire-direction data to the firing battery. The computer was designed for 105 mm howitzer firing problems within a range of approximately 16,000 yards.
What This Manual Covers
TM 9-1220-206-12 explains operation and organizational maintenance of the M15 Gun Direction Computer. It addresses the equipment as both a computing unit and a working part of the M35 fire-control system.
- M15 Gun Direction Computer description and identification
- Operating controls, indicators, and data-entry functions
- Calculation of field-artillery firing data
- Use within the M35 Field Artillery Fire Control System
- Power, console, and data-transmission connections
- Operator care and preventive maintenance
- Organizational inspection, servicing, and troubleshooting
Key Features
- Official publication number: TM 9-1220-206-12
- Publication date: February 1960
- Manual scope: operation and organizational maintenance
- Primary subject: M15 Gun Direction Computer
- Electromechanical analog field-artillery computer
- Part of the M35 Field Artillery Fire Control System
- Configured for 105 mm howitzer firing problems
- Calculated deflection, quadrant elevation, and fuze data
Why This Manual Matters
The M15 marked an important stage in the automation of U.S. Army field-artillery fire direction. Its gears, shafts, and electrical systems reduced calculation time and allowed firing data to move from the fire direction center to the battery more quickly than manual methods.
This manual is a useful reference for studying the M15, the M35 fire-control system, 105 mm howitzer operations, early analog computing, and the transition to digital artillery computers during the Cold War.
About This Manual
The publication offered is Technical Manual TM 9-1220-206-12, dated February 1960, for the M15 Gun Direction Computer.
No M15 computer, M1 console, power-conversion equipment, generator, cables, artillery equipment, tools, test equipment, or other manuals are included.
Ideal For
This manual is a strong fit for:
- U.S. Army technical-manual collectors
- M15 Gun Direction Computer owners and researchers
- M35 fire-control system reference collections
- 105 mm howitzer and field-artillery researchers
- Analog and early military-computer collections
- Cold War fire-direction displays
- Museums, archives, and military-history libraries
Approx length 8", Approx width 10", Approx height .25", Approx weight 1lbs.
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