Wednesday, August 6, 1986

C17 Globemaster HUD

Much of my time at GEC Marconi Avionics was spent on the C17 Globemaster project.  GEC were putting together an avionics package including the Head Up Display (HUD).  HUD systems back then were usually comprised of two parts; the optics assembly, mounted in the pilot's field of view, and the computer system that drives the optics.

C17 Globemaster

I don't know what HUD technology looks like now but back then, HUDs were based on CRTs with vector scanning. This required analog connections to CRT/Optical module, usually X, Y & Z where X and Y are the left/Right and up/down signal controls and Z is on/off.  

My role in this project was to take the digital data from the frame buffers, and turn them into analog signals. The challenge here was this had to be 14 bit accurate over the MIL-STD temperate range of -55C to +125C.  That is a tremendous amount of thermal problems.

Everyone gets a HUD
Back in those days, surface mount technology was just beginning to be a main stream thing, and the issue when dealing with extended temperature ranges was the surface mount components popping off the boards when subject to temperature extremes.

The temperature and accuracy challenges were eventually overcome and as we can see, the Globemaster is  extensively used, 25 years after I worked on it.