[ARC5] GF-11 in airplanes

[Mike Hanz]

Jack Antonio wrote:

>But a couple of questions pop up:
>
>The GF-11 was a 12V set.  When did the services convert from 12 to 24V electrical 
>systems?  As far as I know, all the SCR-274N, ATA/ARA sets were 24V, and were in
>production well before our entry in WWII, but this GF-11 coil set has tags dated
>October 1943.
>
Grant and Peters defined the tradeoffs in battery voltage vs system 
weight for a variety of aircraft in a paper dated October 1939, which 
post dated the classic Eddy and Morgan aircraft radio texts of that year 
that describe only 12v supplies.  It showed that for lighter aircraft 
the system weight difference was small, but the larger the aircraft, the 
more overall weight was saved.  So, I suspect that 1939 is roughly the 
point at which new aircraft designs started using 24v, especially in 
larger patrol and bomber type airframes.  Existing designs continued to 
use 12v for many years, however - the effort necessary to convert unless 
it was a completely new series just didn't argue for replacement.  I'm 
sure you could find exceptions to the rule, though.

73,
Mike