Syncronising/syncrophasing
The Aeroproducts 3 blade prop (15 feet diameter) on the C130A could be operated in basic hydraulic governing as an individual unit, it could be electronically governed as an individual unit or it could be syncronised with other props. No 1 or No 2 could be selected as the master prop and the others slaved to it. There was no syncro-phasing provision. Later C130's with the 4 blade HS prop (13 feet 6 inch diameter) had syncro-phasing which did help lower the noise level and lower vibration levels. Of course the distance between passing blade tips was greater with the HS and also the tip speed was lower due to the smaller diameter. Although the Aeroproducts prop was a bit noisier, it was a simple prop and could be changed much quicker than the HS. The sound of an A model was distinctly different to later HS equipped aircraft, all of which used the Allison T56 powerplant. As for reliability, in my RAAF days the catch-cry was "A's are for GO - E's are for Show" when we operated these two models in different squadrons. With only 12 of each in each squadron it was the A model that got the whole twelve in a formation fly-past, something the E model didn't ever achieve to my knowledge. A few celebratory ales went down at "Ma's" pub that day.