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A Kiwi inventor believes his real-life jetpack will repay a near $1 million investment by taxpayers "twenty-fold" as he lines up customers around the world.

Glenn Martin, of Christchurch, created an international sensation when he exhibited his Martin Jetpack at America's biggest consumer airshow, EAA Airventure in Oshkosh, Wisconsin, in July.

The demonstration was less than spectacular and created plenty of scepticism, but it also gained huge worldwide media attention and Mr Martin says he is negotiating with 53 "official" customers.

Now his company's work is to receive a $968,430 boost from the government's Foundation for Research, Science and Technology.

"I believe the New Zealand taxpayers are going to get that money back twenty-fold, and then some over the next few years," Mr Martin told the Herald.

He claims his jetpack, developed over 27 years, will be world-changing technology.

The foundation said its money would enable Mr Martin to improve the performance and safety of the jetpack.

The investment was the second in the project, following $500,000 in February last year for earlier research and development.

The foundation's business investment director, Eileen Basher, said the investment was being made because of the invention's international potential.

"This is a challenging project, but Glenn Martin has a track record of improving each prototype and has experienced people around him to build the company," she said.

"Its success would reinforce New Zealand's reputation as a high-tech country."

The foundation said several firm orders had been received for the jetpack, and expressions of interest had come from many other potential buyers.

Mr Martin said the US airshow debut was a "public relations coup".

He had expected his jetpack customers to be mostly people seeking "rich boys' toys".

"But I was also surprised at the number of commercial approaches I have had from a wide range of organisations around the world, from search and rescue, police, and all sorts of promotional companies.

And we also got quite a lot of scrutiny from military organisations.

"We have had some customers talking to us about buying 25 units, and other customers talking about buying 100 units."

The first jetpacks were to be delivered to customers late next year.