Jet design has foreign companies fired up

By MICHAEL FOREMAN

A New Zealand inventor has caught the eye of the aeronautical community with the X-Jet, a jet engine that dispenses with costly turbine blades.

The engine's developer, Bruce Simpson, said the X-Jet was derived from the pulse jet engines that powered the V1 flying bombs, used by Germany in the Second World War.

"Development of pulse jets stopped at the end of the war," said Mr Simpson. "What I've done is to take up a 1950s state of development with 21st century materials and techniques."

Mr Simpson said his design had overcome many of the limitations of the traditional pulse jets, including high fuel consumption and a short life.

"A pulse jet lasted typically for about 20 minutes. That was fine for a V1 as they only needed to fly for that long, but it's obviously no good for anything else."

Mr Simpson said his prototype X-Jet had already been test run for 30 hours without suffering any damage. The X-Jet consumes fuel at half the rate of a traditional pulse jet while doubling the thrust.

"These engines run on anything that burns. I've been using liquid petroleum gas (LPG) because it's convenient, but you could just as easily use diesel, kerosene or you could run it on hydrogen if you wanted to."

The prototype X-Jet weighs about 2kg and gives 27kg of thrust, but Mr Simpson said the design could easily be scaled up for a variety of applications.

The smallest jet turbines cost around $US30,000 ($71,700), but a production version of the X-Jet, capable of propelling a light aircraft at 200 km/h, would sell for $US1500.

"It's not what you would use in a 747, but it's ideal for applications where you need a good power-to-weight ratio such as microlight aircraft, aerial target drones, remotely piloted reconnaissance vehicles, or even boats and cars."

Mr Simpson was able to pursue his interest after he sold his shareholding in the news website 7am.com.

"For years I'd wanted to have a workshop and all the proper tools to do this, but I'd always been too busy and never had enough money."

Mr Simpson has spent about $10,000 kitting out his workshop in the garage of his South Kaipara home, but he has budgeted $100,000 for further development of the X-Jet.

"I've had to make everything myself, as there aren't any stores where you can buy bits for pulse jets."

Mr Simpson has been awarded a $30000 grant from Technology New Zealand.

As soon as he has secured patents, he plans to sign contracts with overseas manufacturers.

Since he posted details of the X-Jet on his website last month, he has received 15 sales inquiries, including five companies in the United States.

From the website records, he is aware of about 300 individuals who are keeping a close eye on the engine's development. "I can tell from the logs this includes people from the [engine manufacturer] General Electric, Nasa and various other parties."

Mr Simpson thinks it is quite likely that his version of the pulse jet will be used for its original purpose - to power small cruise missiles.

Aardvark