As dawn breaks I’m careening down a desert runway in southern New Mexico. I’m in a “kite wing”; little more than a souped-up trike, it’s a three-wheeled go-kart with wings, two seats and no enclosed cockpit.

As we quickly pick up speed, John McAfee, the pilot, who’s sitting inches ahead of me, pushes forward on the struts attached to the wings and suddenly we’re soaring hundreds of feet a minute up into the still starry skies, the cold morning air whipping against our faces as the vastness of the New Mexico desert drops away.

All that’s keeping me from falling two or three thousand feet, my shattered bones to be picked over by coyotes, rattlesnakes and scorpions, is the small seat underneath me and the belt strapping me to it. Otherwise I am open to the elements as we glide and bank and then drop at speeds approaching 100mph.

Welcome to the world of the Sky Gypsies, members of a club dedicated to the new sport of aerotrekking. To join, you need two things: nerves of steel and a head for heights. This is one of the most exciting adventure pursuits around, and the premise is simple. Groups of pilots, sometimes as many as 40, take to the sky in these lightweight craft and head across the vastness of the deserts and mountain ranges of New Mexico and Arizona, skimming at times only a few feet above the ground.

Like a crazy band of airborne bikers, they’ll journey together for days at a time, stopping off overnight at small airports and runways. The landing strips form a 900-mile circuit specially devised and mapped. It’s a bit like ski pistes that allow skiers to explore a vast terrain safe in the knowledge that they can stop to relax and refuel at mountain restaurants.

Since 2005, McAfee, who founded the McAfee antivirus software company in the late 1980s, has spent some $14m (£6.8m) on this project. You probably have software made by the company protecting your computer from digital attack. However, McAfee sold his shares in the business in 1994 for a cool $100m – which has given him ample capital and plenty of free time to indulge his passion.

I’m here for three days but this is how he and his Sky Gypsies spend much of their lives: getting up before dawn, pulling on their flight suits as Jimi Hendrix pumps through the hangars, checking the winds and heading out for a new adventure.

Now 62, he looks like a pirate Richard Branson, tanned, with hooped gold earrings, a goatee, brown hair with frosted blond highlights, tattoos down his arms, the antithesis of the American businessman he once was.

McAfee, who was born in Gloucestershire but moved to the US when he was two, got the idea for aerotrekking in 2002 when he was flying to Nepal with Jennifer Irwin, his girlfriend. They read an article in the in-flight magazine about “trikes” – light, single-engine planes with flexible wings like hang-gliders (microlights, by contrast, have fixed wings) – and both were transfixed.

When they got back to the US they started taking lessons but McAfee soon felt these craft should be doing far more than circling round small airports for a couple of hours. Over the next year he and Irwin drove around the American southwest looking for somewhere they could use as a main base.

They eventually found what has become their operational centre, in the sleepy little desert town of Rodeo, New Mexico, population about 200, a few miles east of the border with Arizona and about 90 miles north of the Mexican border. There was an airstrip and McAfee bought up an 80-acre parcel of land immediately around the strip as well as some other plots nearby.

Since then, he has built four large hangars for the craft and has added a large internet cafe with a 35-seat movie theatre, around which are dotted old, revamped Airstream trailers in which Sky Gypsies or visitors can spend the night for $45 (£22). McAfee and Irwin live in a villa on the compound, which has a constant stream of Sky Gypsies dropping by for coffee, snacks and “hangar stories” about their daily flying exploits.

Each of the six other stations McAfee has set up across the aerotrekking circuit also have airfields, hangars and access to fuel and food, with rudimentary but comfortable accommodation nearby. The lightweight machines with their open cockpits mean you get the sensation of flying like a bird. At the same time, the opportunity to fly along a predefined route means you won’t encounter sudden unexpected changes of terrain or obstacles.

The craft McAfee and his Sky Gypsies fly, usually Tanarg iXess machines, can cost anywhere from £41,000 to £97,000. They have 1200cc four-stroke Rotax engines behind the back seat powering the prop at the rear, off-road tyres and suspension for rough landings, dual controls and GPS navigational and communication equipment.

Most also have a parachute. Because they don’t have fixed wings, they are extremely manoeuvrable and because they are so light they have a range of some 300 miles, which can mean as long as four hours in the air.

While they can reach speeds close to 100mph, they can also skim along just above the ground at little more than 25mph. Some Sky Gypsies like to take them up to about 14,000ft and switch off the engines, staying aloft as long as they can. Some have even taken them across the Mexican border, flying too low to be picked up by the border radar.

McAfee likes to touch his wheels on both sides of the interstate freeway, between traffic. That kind of mad adventurism is what appeals to McAfee about his band of Sky Gypsies.

“I wanted the reverse of my early life in the business world,” he says, “where everybody dressed alike, adhered to the business culture and attitudes, lived in identical houses, and had identical cars.

“I wanted people who could bring true individuality from a life lived in as much freedom as possible.”

This all may sound a little dangerous, but McAfee insists the craft are reliable, and are statistically far safer than driving a car. However, there has been one serious accident. While flying between a mountain range in November 2006, McAfee’s nephew and a passenger crashed their plane and were killed.

Despite this, McAfee remains a dedicated flyer and his club is growing rapidly. There are about 400 Sky Gypsies, of all ages and from all backgrounds including retired F-16 pilots, old hang-glider enthusiasts who will do anything to get into the air, mothers, career refugees like McAfee, thrill seekers, stunt pilots and weekend Top Guns.

Membership costs anywhere from $1,000 (£486), which gives access to the facilities at Rodeo for a week, to some $270,000 (£131,000) a year, for which you can use all the Sky Gypsy airfields, accommodation and cars.

About 25 hardcore members spend up to six months a year on the sport, while a smaller group – including McAfee, Irwin and some hardcore instructors – are in Rodeo about 90% of the time. But McAfee is keen that anyone interested in trying out the sport should be able to afford it.

In order to fly solo, you’ll need to have a light-sport aircraft licence. Passing the test can be achieved with as little as 15 hours of airtime, and flight instruction costs between about £73 and £97 an hour.

“We welcome anyone who wants to come and visit,” he says. “We’ll put you up, we’ll find someone to take you flying; you can hang with us.

“We don’t invite everybody to become a Sky Gypsy, but we certainly invite everybody who has an interest to come and check us out.”

On the afternoon I leave Rodeo, McAfee is checking to see whether he’ll be able to fly again that evening when the winds usually die down.

“I like to head out across the desert and after we pass all the mesquite and we’re left with nothing but the brush, I like to let my feet dangle and feel the brush scrape the bottom of my shoes,” he says.

“You see the perfection of nature but you also feel your own insignificance because you’re travelling through this immensity which even in the desert is full of life and activity and drama, this incredible dance of existence.”

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