I saw a clever design for a general aviation GPS the other day. Normally a GPS unit is a rectangular box, the same size and shape as other electronic gear, like nav/com radios, and transponders. Like a car CD player: a rectangular face on a long box that slides into the appropriate spot in the radio stack.
Not everyone has room in their avionics stack for another box, even when they want a GPS. But a lot of airplanes have spots for extra round gauges. The GPS display that I saw was designed to fit and bolt into a round dashboard hole that had previously accommodated an ADF. The ADF is a venerable navigation instrument, still very much in use, but not nearly as accurate, easy to use, or as sexy as a GPS. I'm sure they've been around for years, but it was the first I had seen and I applaud cleverness, even belately.
The first airplane I remember well had no avionics stack and no rectangular radios. The com and nav frequency selectors were on round instruments that looked a lot like the ADF and gyrocompass displays; the actual radios were brass-colored boxes mounted somewhere near the firewall. I thought rectangular boxes were a great step forward, and I remember wondering whether all instruments would be similarly regularized.
Though ultramodern glass cockpits have taken that idea to the next level, it seems that round holes will be around for a while.
GPSs built specifically for use in gliders (sailplanes) often use the round hole form factor. Often they're combined with the vario in which case they're typically 80 mm, some are GPS only in which case 57 mm is likely.
Post a Comment