Needless to say, it did not go well. His contraption didn’t fly and he was made to fix the fence.
“I was brought up in a way that I guess challenged me scientifically… I was always told that nothing’s impossible,” he says.
Perhaps he got a bit ahead of himself during his childhood in Sydney, but as an adult Mr Mayman, has built innovative machines that really do fly.
But, since 2018, he has been working on a different kind of project, one he thinks will have more commercial opportunities.
The second prototype the P1.5 being tested in California
That might seem like a step backwards in technology, but for the customers Mr Mayman has in mind, only liquid fuel will do.
For that, you need jet fuel, as it stores 20 times the energy of batteries for a given weight. Or in other words, to supply the power needed, batteries would be too heavy.
“If you want to carry a certain payload, and you want that aircraft to have a certain range and certain speed, the only way to do that with current technology is, with turbine engines.” Mr Mayman explains.
“As is so often the case in aviation, you start with one set of specifications, and fairly quickly, you end up with an entirely different set of specs,” he explains.
“They initially wanted something that would carry a payload of 210 pounds (95kg), not far into the project that morphed to nearly 300 pounds (135kg). And they wanted it to be possible to train somebody literally in 10 minutes,” Mr Mayman says.
To simplify things, while on the jetpack the direction of thrust is controlled mechanically by the pilot on the Speeder the angle of the four jet turbines is controlled by an electronic flight control system.
The key part of that system is bespoke software that understands the physics of the four very powerful jets. This means that when the pilot lifts-off or turns, the Speeder can angle its jets to make that happen.
“It’s effectively AI (artificial intelligence) – if you want to call it that – that understands what the vehicle is going to need… so it can start instructing the engines to be spooling up or spooling down,” says Mr Mayman.
Sajal Kissoon working on a gas turbine at Cranfield University
Mr Mayman is hopeful that the Speeder will eventually be used to transport cargo. Piloted by remote control, or autonomously he thinks there will be demand particularly from the armed forces or emergency services.
In cargo mode, where it is piloted remotely, it will be able to go even faster, perhaps at 500mph and carry 450kg.
Being compact and able to fly in all sorts of weather conditions, he thinks it has the potential to be more versatile than a helicopter.
Mr Mayman intends to be the first to fly the Speeder
But before you get too excited at the prospect of ditching the bus and hopping on a Speeder to work, Mr Mayman says it is unlikely to fly through cities.
“We make noise, we’re incredibly powerful, we’re incredibly small. I don’t think there’s necessarily a need within the urban air mobility space for an aircraft that can be the size of your kitchen table.”
Crucially, a lot more testing still needs to be done before the Speeder is delivered to any customer. A third full-size prototype (called the P2) is being prepared for flight at test range about two hours east of Los Angeles.
There will be enough space there for the Speeder to be put through its paces.
A key phase will also come late next year, when the company hopes to start the certification process. The company estimates that will take 12 months.
Unsurprisingly, all of his engineers want to be the first to fly the machine out in the desert, but Mr Mayman is saving that thrill for himself.
“It’s pretty much the main reason they work here. So, I have got a long queue of folks waiting to test fly this thing. But I’ll be pulling rank,” he says.
And hopefully for Mr Mayman, this time he will not have to fix any fences.