RTX Corporation
Founders
Laurence Marshall, Vannevar Bush, Charles G. Smith, Frederick Rentschler · Founded 2020 · HQ today: Arlington, Virginia
RTX was founded by Laurence Marshall, Vannevar Bush, Charles G. Smith, Frederick Rentschler in 2020. It is now led by Christopher T. Calio.
RTX traces two separate lineages. Raytheon began in 1922 in Cambridge, Massachusetts as the American Appliance Company, founded by Laurence Marshall, Vannevar Bush and Charles G. Smith, and later became a major radar maker in World War II; a Raytheon engineer, Percy Spencer, developed the microwave oven in 1945. Pratt & Whitney Aircraft was founded by Frederick Rentschler in 1925 and became the core of United Aircraft, later United Technologies. The two lines combined in April 2020.
American physicist and entrepreneur.
Laurence Marshall co-founded the American Appliance Company in 1922, which was eventually renamed Raytheon. He spearheaded the company's early massive success in producing highly reliable vacuum tubes for the booming radio market. (Exact birth year remains publicly undisclosed).
Legendary American engineer and science administrator.
Vannevar Bush co-founded Raytheon. As an absolutely legendary engineer and dean at MIT (and later the head of the US Office of Scientific Research and Development during WWII), he provided the absolutely critical scientific credibility and deep government connections required to secure massive defense contracts. Vannevar Bush was born in 1890.
American scientist and inventor.
Charles G. Smith co-founded Raytheon. He invented the 'S tube,' an absolutely revolutionary gas-filled rectifier that completely eliminated the need for highly expensive, short-lived batteries in early radio sets, launching the company into massive profitability. (Exact birth year remains publicly undisclosed).
American aviation pioneer.
Frederick Rentschler founded Pratt & Whitney Aircraft in 1925 (which later merged to form United Technologies, now part of RTX). He was an absolutely visionary engineer who designed the legendary 'Wasp' radial engine, a remarkably reliable air-cooled engine that completely revolutionized commercial and military aviation. (Exact birth year remains publicly undisclosed).
Christopher T. Calio
Chairman and Chief Executive Officer
Under Calio, sales grew to $88.6 billion in 2025 and backlog reached a record $289 billion by mid-2026. He previously served as RTX president and COO and as president of Pratt & Whitney.
Frederick Rentschler
Pratt & Whitney founder
As the founder of Pratt & Whitney, he built the absolute core aerospace foundation of the massive conglomerate that would eventually become RTX.
RTX was created by the merger of two historic enterprises: United Technologies (founded as United Aircraft in 1929 by Frederick Rentschler) and Raytheon Company (founded in 1922 by Laurence Marshall, Vannevar Bush, and Charles G. Smith).
Frederick Brant Rentschler was an American aviation pioneer who founded the Pratt & Whitney Aircraft Company in 1925 in Hartford, Connecticut. He designed the revolutionary 425-horsepower air-cooled "Wasp" radial engine that transformed naval and commercial aviation.
In 1929, Frederick Rentschler teamed up with William Boeing to form United Aircraft and Transport Corporation, combining Pratt & Whitney, Boeing Aircraft, Chance Vought, Hamilton Standard, and United Airlines into the world's first integrated aviation trust.
Following the Air Mail scandal of 1934, the US Air Mail Act barred airframe manufacturers from owning airmail airlines. United Aircraft and Transport Corporation was forcibly broken into three independent companies: Boeing (manufacturing in Seattle), United Airlines (transport), and United Aircraft (East Coast engines and propellers, later UTC).
Dr. Vannevar Bush was a legendary MIT electrical engineer, inventor of the differential analyzer (early analog computer), and science advisor to President Franklin D. Roosevelt who coordinated the Manhattan Project. In 1922, he co-founded the American Appliance Company (Raytheon).
Laurence K. Marshall was a civil engineer and venture visionary who partnered with Bush and Charles G. Smith to commercialize Smith's helium rectifier tube (the "Raytheon tube" or S-tube), which allowed home radios to run on household AC electricity without expensive batteries.
In 1925, the American Appliance Company changed its name to Raytheon Manufacturing Company. "Raytheon" is derived from Greek words: "ray" (light or beam) and "theon" (of the gods), translating to "light of the gods."
In 1945, Raytheon radar engineer Percy Spencer was testing an active magnetron tube when he noticed a candy bar in his pocket had melted. He experimented with popcorn kernels and an egg, patenting microwave cooking and launching Raytheon's "Radarange" in 1947.
During World War II, Raytheon mass-produced over 80% of all cavity magnetrons used in British and American microwave radar systems, giving Allied ships and night fighters decisive tactical advantages over German U-boats and aircraft.
Charles Grover Smith was a brilliant physicist who studied gas-discharge physics and invented the cold-cathode rectifier tube that eliminated the need for batteries in early consumer electronics, establishing the commercial viability of Raytheon.
Frederick Rentschler is enshrined in the National Aviation Hall of Fame; Vannevar Bush has MIT buildings and the prestigious National Science Foundation Vannevar Bush Award named in his honor; Percy Spencer is inducted into the National Inventors Hall of Fame.
The founders established twin technological pillars that define modern RTX: Frederick Rentschler's uncompromising standard of propulsion mechanical reliability, and Vannevar Bush's ethos of state-of-the-art electromagnetic and radar innovation.
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