Steam gages
 

Virtually all aircraft pre-glass-cockpit used instruments of a standard panel-hole dimension - either 3 1/8" or 2 1/4". There were exceptions - the old artificial horizon was larger.

But what is the origin of these dimension standards? Did Kollsman or one of the other companies establish the dimensions? Or was it a military specification? :confused:

Generally, on civil types, these standard deminsions were developed by Kollsman, Sperry, and Collins.
On the DC-6 for example, the panels were precut at the factory in Santa Monica, with a standard layout, then fitted with the avionics and instruments specified by the specific airline customer.
Radar was not generally used on civil types (again, DC-6 for example) and was added later...not a bright tube display either, it required a hood to read the display in the daylight.

Ah...the good 'ole days.:rolleyes:

Geez, I remember using that hood on the DC-3. We had an ex-executive machine, CF-ORD, that came to us from an auto manufacturer that shall remain nameless. It had the dash 94 engines, weather radar and the one-piece windshield. Thought we'd hit the big time. :O

The only Viscount I've got stick time on had the weather radar down by the left side of the Captain's seat. Was that an aberration, or was that the usual location?

Originally a military specification.

We old RAF instrument bashers were led to believe it was standardisation for wartime production. Wartime mass-production meant using as many common parts as possible and instruments were no exception. For example, instrument cases and their glass faces from the same manufacturer often shared the same part numbers across instrument ranges - altimeters, airspeed indicators, VSIs and even RPM indicators might all share the same face plate and glass.

Aircraft of all types had what was called a "standard blind flying panel' installed. It wasn't just a standard layout either - you could even draw a complete blind flying panel from stock and just hook up the hoses. Take note of the way the same standard panel is integrated into both a Lancaster pilot's panel and a Stirling. You might find exactly the same panel integrated into the pilot's panel in any other type of aircraft.

Ah yes, only the radar that the Captain can see.
Good show, on these types, as this keeps the co-pilot in the mushroom syndrome...:E

Just kidding....maybe.:E

Yes, but why 3.1/8th" and 2.1/4" Somewhat odd sizes to choose for no particular reason.

I think its something to do with basing instrument dimensions on the watchmakers' ligne as a calibre measure for watches.
So we can blame the Swiss... ;)