* In development for 30 years
* Shipping to start by end of year
* "Strap it on, rev the nuts out of it"
ROCKETEERS take note: the wait for your very own jet ski in the sky is nearly over, according to the New Zealand company behind an ambitious aeronautical project.
The Martin Jetpack, literally a strap-on personal flying machine, is now in the final stages of development, with the first machines to be dispatched for solo flights by the end of the year.
Military agencies, border control and rescue organisations in the US will be the first to use the pricey $NZ100,000 (about $75,000) aircraft.
Inventor Glenn Martin predicts it will be just 18 months before other wealthy enthusiasts get their delivery.
"We've had 2500 people sign up for one so far, and plenty of them from Australia," Mr Martin said.
Their plans for the expensive toy range from practical - "some just want to dodge the rush-hour traffic and do it in style" - to the purely frivolous.
"We know of someone that would love to do stunts flying across Sydney Harbour. How amazing would that be?" Mr Martin said.
The jetpack resembles two leaf blowers welded together but its capabilities are much more complex. The two-litre, jet-powered engine can soar across the skies at 100km/h at heights of up to 50m.
Carrying enough fuel to fly for 30 minutes, the contraption could be used in hard-to-access areas and war zones to patrol borders and, if unmanned, to make difficult deliveries by remote control.
"Some of that might sound boring but where there's huge cost savings and an increase in efficiencies for agencies it's actually hugely exciting," Mr Martin said.
Recreationally, it could be used to go fishing and, one day, get to work.
For now, however, it is categorised as a microlight so it cannot be taken into the city centre, however this may change under US law.
Martin's machine, lauded as Time magazine's most anticipated invention last year, has been more than three decades in the making.
The Christchurch man began tinkering with the concept in the 1970s, inspired by the limited success of the US Bell Rocket Belt, which stayed airborne for just 26 seconds before crashing.
A gas-guzzler in the extreme, the belt burned through $US2000 worth of fuel in 30 seconds.
Mr Martin's latest and most celebrated version, unveiled at an air show in 2008, is more fuel efficient, costing just 15 US cents for 20 seconds in the air.
It was designed to be the "simplest aircraft in the world," said Mr Martin, who has described how "you strap it on, rev the nuts out of it and it lifts you up off the ground".
"It's basic physics. As Newton said, for every action there is an equal and opposite reaction. So when you shoot lots of air down very fast you go up and you're flying."
He said the interest had been overwhelming, with inquiries coming from Middle Eastern royalty, US business tycoons and European daredevils.
The Australian Government hadn't officially registered its interest but, judging by website traffic, the Australian Defence Force was a fan.
"It's the fourth biggest visitor to our site after Boeing, NASA and the SAS, so something's going on there," he said with a laugh.
"Maybe they've just got an employee who thinks it's so cool they spend all day checking it out."