His wife Colleen Lapp told The Canadian Press that her husband died in hospital near Toronto on Wednesday after a long illness.
The aeronautical engineer's list of achievements included helping to build Canada's first satellite; working on the early NASA capsules; leading the mechanical-engineering division on the famed Avro Arrow project; co-founding SPAR Aerospace, which built the first Canadarm; and co-authoring major space policy.
But he didn't brag about it.
"We didn't blow that horn loudly," Lapp said in a 2011 interview with The Canadian Press, describing his contribution to the antennaes for NASA's Mercury, Gemini and Apollo space capsules.
"Probably we should have. But this is the Canadian way, you know. So we didn't make the exaggerated statements that you hear from other parts of the world."
Lapp was instrumental in the construction of Alouette — Canada's first satellite, which led the country to become the third nation in space after the United States and the Soviet Union.
He also helped establish the Canadian Astronautical Society, the predecessor to the Canadian Aeronautics and Space Institute.
His wife lauded his human side in an interview Thursday.
"He was just a really bright man," Colleen Lapp said.
"But he had a common touch... He got along with everyone."
He volunteered his time as a member of the board of the Canadian Air and Space museum in Toronto until he became ill.
Robert Godwin, who served as the museum's space curator, said Lapp leaves behind a huge legacy.
"His hand was in so many of these different things that we now attribute to our Canadian air and space program," Godwin said in an interview from Toronto.
He noted that Lapp was the head of mechanical engineering on the Avro Arrow (CF-105) — "a legendary piece of Canadian engineering."
The Avro Arrow was considered the most advanced military aircraft of its time but the project was cancelled by the Diefenbaker government in February 1959.
Volunteers at the Toronto museum built a full-scale metal replica of the aircraft.
Lapp got his start doing his thesis in the U.S. at MIT on long-range ballistic missiles in the 1950s. He designed the guidance system for one of the first rockets the Americans developed, under the classified Atlas program, and says he returned to Canada "with a lot of space stuff in my head."
Godwin also said Lapp co-authored the "Chapman report" which launched Canada's space policy in 1967 and which, he added, has influenced Canada's space program ever since.
But he said what really struck him was that, despite his list of accomplishments, Lapp was a quiet and humble man.
"He was so soft-spoken, did not blow his own horn, but when he spoke people tended to listen because usually what he said was worth hearing," Godwin said.
"It was always a quiet, calm, considered opinion and you can tell you were getting sage advice when Phil spoke."
In the 2011 Canadian Press interview, Lapp discussed the 50th anniversary of the historic first human space flight by Russian cosmonaut Yuri Gagarin.
He admitted that he admired the Russians back then even though he was frustrated because they had more success with their rockets than the Americans.
"When Gagarin was in orbit, it's probably fair enough to say that I was probably frustrated that we, the western world, were beaten by the Russians again with putting a man in space," Lapp said.
"That was quite an achievement. I had to mix my feelings with an admiration that the Russians were able to do it."
Lapp was working with a group of young engineers at the De Havilland aircraft company in the 1950s and early '60s at its Guided Missile Division, just outside Toronto.
Lapp, who was appointed an Officer of the Order of Canada in 1995, leaves behind a wife, stepdaughter, and two sons and a daughter from a previous marriage.