Ask, and ye shall receive:

When the use of planetary propeller reduction gears became more widespread in the early 1930s, it did not take long for someone to realize that with all those equal and opposite reactions going on inside the nose case, some might lend
themselves to measuring torque. With this knowledge and a little math a pilot could tell exactly how much power was being delivered to the propeller in real time:

If the turbo compound engine were to be invented today, those engineers would be considered geniuses. It still blows my mind that the correct metallurgy was available to develop these engines.

Great stuff and great topic!

A turbo compound engine is just a turboprop with pistons in the way.

God I love this site..........sometimes.

Thanks for that one Tony!

The Convair 440 I flew (twin P&W R2800s) had RPM, MP (66" on takeoff!) and BMEP gauges. Lots of moving parts on that bird, always exciting!

The not much more modern Fokker F-27 (twin RR Darts) had RPM, EGT and prop dome oil pressure. One confirmed the oil pressure reading with an engine specific reference number to determine if takeoff power was achieved.

The Airbus A320 I now fly is just point and click, click (and sometimes a third click for TOGA). Much more go force but somehow less exciting.

I was a member of the Commemorative Air Force, and took the ground school (and flew) the C-46. I think it had the 2000hp Pratt & Whitney R2800 Double Wasps.

The CW-46 had an early model R28 but I'm not sure what Fred was doing. The CB17 only went to 62 inches wet with brown gas and it was the ne plus ultra of R2800s.

We were in a location that had unlimited access to the purple stuff (115/145). I hear it was backed off quite a bit with the 100/130. I mostly flew the DC-3, 1830-94s with 48 inches on purple juice, I think it was 42 inches on 100/130. That was a long time ago!