The Canadair CL-84 Dynavert was part helicopter, part airplane and a complete flop.
The aircraft, built and tested in the 1950s and 60s, had sloping wings, so it could hover and land like a helicopter but could fly forward like a plane. Canadair killed the CL-84 program when it could not find a buyer, and the aircraft was forgotten.
But now a Swiss aviation company has revived the design with a modern spin. Dufour Aerospace’s Aero 3 is based on the CL-84’s aerodynamic shape and concept, but burns fuel and electricity to power the eight-seat aircraft.
Dufour aims to bring a hybrid gas-electric version of the aircraft, a cheaper and more efficient alternative to air ambulance and rescue helicopters, to market by 2025.
The company has received letters of intent to buy the Aero 3 production for about three years. Dufour is eyeing a potential Canadian manufacturing facility in addition to a European base, Dufour’s chief executive Thomas PfMatter said from Zurich.
“The principle has become useful again,” said Erin Gregory, curator of the Canada Aviation and Space Museum in Ottawa, where one of the two remaining CL-84s sits on display.
“It stands out because it’s a weird looking airplane, for sure,” said Ms. Gregory.
The Aero 3 will cost between US$2.5 million and US$5.4 million, and will operate at a cost of approximately US$1,500 per hour. A typical helicopter can cost several million dollars, and costs US$20,000 per hour to operate. Every hour in the air requires four hours of maintenance on the ground.
In 2015 Dufour became one of the first to build an all-electric stunt aircraft, the Aero 1, and is building a pilotless version of the Aero 3.
To design the four-engined Aero 3, Dufour engineers studied flight data, NASA research papers and other publicly available information on the Canadair CL-84, which was launched in 1974 after the US military decided not to order it. died after.
“It’s a known aerodynamic concept that has been perfected by pilots, many dozens of them, who flew that plane in the sixties,” Mr Pfmatter said over the phone. “Aviation is so difficult and you have so many unknowns that you want to limit your risks. There is a lot of material on tilted aircraft data, how they fly and how they behave in what situations.”
The CL-84 was one of several tilting aircraft developed in the 1950s and 60s.
“There are some examples,” said Ms. Gregory, “some that never took off, some did some test flights but didn’t go very far, others that were like failures out of the gate.”
“The idea was to try to get something that had all the benefits of a helicopter without the limitations of a helicopter, and then all the benefits of a fixed-wing aircraft without the need for any airspace,” Ms. Gregory said.
The CL-84 failed, but not at first.
Canadair built four CL-84s and flight tested three of them. The design was favored by pilots and extensively tested by the US military, which was looking to use the CL-84 for military transports and gunships in the war in Vietnam.
Two accidents took place due to mechanical failure. And by the early 1970s, America had changed tactics in the war. Instead of intensifying ground combat by bringing troops on helicopters, he began dropping bombs from above.
The US moved away from the CL-84 in 1974. With no other potential buyers, the plane was sanitized.
Today, a CL-84 sits flightless in the Ottawa Aviation Museum, an aluminum embodiment of the dream of flying, the past and – possibly – the future.
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