BUCHAREST, Romania -- A Romanian inventor who claimed he beat the Americans to make the world's first jetpack and went on to design and build dozens of vehicles, calling the modern-day car "a disgrace," has died aged 81.

The hospital in the southern city of Ploiesti said Justin Capra died Monday evening. The cause of death was not given but Capra had diabetes.

Propelled by poverty and curiosity, Capra began inventing gadgets in childhood, and graduated as an engineer. He crafted unconventional flying machines and dozens of prototypes of fuel-efficient vehicles in his lifetime, including in 2011 a single-seater car that did about 200 kilometres to the litre, running on a mixture of gasoline and water. He blamed "social, political, and economic reasons" for his belief that it would never be built on a mass scale.

Romanian Prime Minister Victor Ponta called him "a great Romanian and inventor known throughout the world for his inventions."

In 1956, under communism, Capra invented the "flying rucksack," a personal flying machine. In 1962, one was produced in the U.S. by Bell Aircraft Corp. "All that was different was the colour," Capra insisted in an interview.

There were reports that Capra created the jetpack to escape communist Romania, but he said he had a less ambitious aim, in his time as a conscript in the Romanian army. "I wanted to run away from barracks without the colonel seeing me."

A parachutist tried his invention but crashed. Capra was advised by aviation pioneer Henri Coanda to change the fuel, which he did and came up with an improved version. The same parachutist tried this in 1958 and this time it worked better.

However, under communism, citizens were not allowed to own a flying machine and Capra was unable to patent his invention.

Of automobiles, he said: "They are a disgrace. They weigh 1,000 kilograms (half a ton) and carry people who weigh 60 kilograms.... Of 1 litre of fuel, 980 millilitres shifts the car and 20 millilitres is for us."

He warned with apparent foresight: "Instead of becoming a means of transporting people, (cars) will become a reason for blocking the traffic," because the number of cars exceeds roads being built.

There was no immediate word about funeral plans or survivors.