[Milsurplus] 14 volt C 47s? 14 volt RCAF fighters?

[Boeing377]

When converting an ARN 7 Radio Compass back in the 1960s to run on 12 VDC noticed that the TO showed a military 14 VDC setup using a PE 109 rotary inverter. Back then I couldn't find a reasonably priced PE 109, they were all being bought up by commercial fishermen to run APN 9 Loran A sets on 12 volt boats. I built my own solid state 12 VDC to 115 VAC @ 400 cps single phase inverter that was good for about 450 watts. I could run both an ARN 7 and APN 9. The main drawback of my inverter was that the square waves made the selsyn indicator (I 82) literally screech, but the ARN 7 ADF worked really well 

I was told that the 14 volt setup shown in the TO was for RCAF C 47s that had 14 VDC electrical systems. Why did the make these non standard C 47s? I would think it would add weight in larger conductors needed due to lower voltage. 

I skydive and have been a jumper since 1968. In 1968 mil surplus gun cameras from fighters were used to do air to air skydive filming. The US ones had 28 VDC motor drives. The RCAF versions used 14 volt motor drives, indicating that the RCAF had 14 volt fighters too. The RCAF cameras were highly prized by skydivers as they could run with smaller battery packs. \

What was the reasoning for making 14 volt transports and fighters in WW 2 when the rest of the allies had 28 volt DC systems?

73
Mark
AF6IM
www.parachutemobile.org