A Romanian inventor who claimed he beat the Americans to make the world's first jetpack, and who built dozens of other vehicles, has died aged 81.

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

He crafted unconventional flying machines and dozens of prototypes of fuel-efficient vehicles, including a small car in 2011 that did 470 miles to the gallon (about 200 kilometers to the liter), running on a mixture of gasoline and water.

In 1956 he invented the "flying rucksack," a personal flying machine, in then-communist Romania. In 1962, one was produced in the U.S. by Bell Aircraft Corp. "All that was different was the color," he insisted in an interview.