Turbo-compound: when it was 1st used

[tomo pauk]

Would like to know more about 1st planes/prototypes that used turbo-compound

 

[FLYBOYJ]

I believe the first Turbo Compounds were used in the DC-7 and later model Lockheed Constellations. The turbo compound was supposed to deliver better fuel efficiency but initally shortened engine life.

 

[WJPearce]

For testing, I believe the first R-3350 Turbo Compound was flown in 1949 in the nose of a B-17. I can not think of any prototypes right now, unless you count the R-3350 TC powered Yak 11 Air Racer.

Here is an article that might answer some of your questions:
Turbo Compounds

B-17 from http://www.aerofiles.com/boe-b17turbo.jpg:

Yak 11 from http://aafo.com/racing/images/rheat_01.jpg (note the angle of attack, Skip Holm was the pilot for this picture I believe):

Edit:

I found a prototype, the Stroukoff YC-134. Basically an "improved" C-123:
http://en.wikipedia.org/wiki/Stroukoff_YC-134

Also there was a Martin M-270 which was the XP5M-1 Marlin flying boat prototype that had been reconfigured as a hull design test aircraft.

WJP