Aircraft Computers

1. Computer CK 37

At the end of 1950s it was decided by the Swedish Air Forces to equip the new multipurpose attack/fighter Saab37 Viggen with a computer. It was the central computing and integrating unit for all electronic equipment to support the pilot with necessary information. The computer, CK37, was the first airborne computer in the world to use integrated circuits (with the first generation IC´s). 15 computer prototypes were used 1963 to 1968 in ground and flight tests.

Almost 200 computers were delivered 1970-1978 from Datasaab Production Unit for the aircraft Saab AJ37. The function was reliable and the computers were still in operation, with upgrades, at the early beginning of the 2000´s.

Some data
Instruction speed: 200.000 instructions per sec.
Memory: 25 kbyte, a ferrite core memory.
Communication: 64 analogue in/out signals. 450 bits of binary in/out signals.
Size: 4 units, each between 11 and 16 kg. Power 600 watts.
Reliability: MTBF min. 200 hours during flight operation.

Click to enlarge pictures!

CK37 and interacting electronic equipment to support the pilot.

Circuit unit with an aluminium beam for support of components. Several units are mounted in a frame with interwiring. One computer unit for the aircraft consists of several frames, some of them fitted with connectors to the aircraft.

The aircraft rack with the four CK37 computer units.

The interior of one of the first integrated circuits, which reached Saab in 1961, enclosed in a TO5 capsule with 7 connections. The chip is 2x2 millimetres. Fairchild, USA, was the supplier.

The IC symbols (on a sticker) are placed on a drawing and manually interconnected to a computer block, showing both logic and electric function.

2. 10 years later: Computer CD107

A CK37 frame is compared with a circuit card from the computer CD107. This computer for the aircraft Saab JA37 is a design, about 10 years later. The computer was built on a license from Singer-Kearfott. Almost 100 computers were delivery from Saab Production Unit during 1979-1985.

Read more about the aircraft computers from Datasaab in the book TEMA FLYG, 1995.