Donald Paul Riccardi is a mechanical engineer who worked at Pratt & Whitney Aircraft for 40 years, from 1956-1996.  He was instrumental in introducing single crystal cast turbine blades into the J-58 jet engine (patented by Frank Verschnider at the United Aircraft Research Laboratory in East Hartford Connecticut) Don also worked on turbine disks, made from compacted powder, developed by Roy Athey from the Materials Laboratory in Florida.

Don’s first engine project was the JT-4, the military labeled it J-75. It powered several jet fighters and in a non afterburner mode the commercial airliner called the DC-8. It also powered the high flying U-2, using a modified fuel system. Don tested this engine at very high altitudes in a simulated altitude facility .

In 1958, Pratt & Whitney opened a development center in South Florida.  The remote location allowed privacy for testing and development of a liquid Hydrogen and liquid Oxygen rocket engine. The area selected was situated just out of the range of Russian bombers from over the north pole, at that time. 
The RL-10 liquid hydrogen/ liquid oxygen rocket engine program brought Don to Florida. “We built rocket components, tested them individually, assembled engines and tested the entire system. Over 400 RL-10 engines have been successfully powered objects into the upper atmosphere,” and still in use on the upper stage of ATLAS V. 
Also in Florida, Don worked on turbine material development that ended up improving the durability and operating life of the J-58, and F-100, both still flying. The F-100, with upgrades, powers the F-15 and F-16.  Don worked on the Airborne Lasar Program, which was designed to vaporize enemy threats. “We built components and tested the full up system by burning holes in steel plates.”
Don ran a standard jet engine, modified to run on liquid hydrogen, named the “Suntan” program under Dick Mulready,
In Don’s words, “I was just a go-to turbine engineer that got the job done, and had fun doing it.”

“This is a mock-up, not real parts, of the RL-10 I worked on starting in 1958. I am pointing to the LOX pump that I ran on a test rig, and my improvements were incorporated into the production model, still flying.”