Human sling flings BBC reporter Willie Johnston

The first slight pang of apprehension strikes as I pull into Laggan Outdoor's car park. I return owner Duncan McConchie's welcoming wave as cheerily as I can, but what I'd been totally blasé about until now is starting to feel a bit scary. The feeling is magnified on first sight of the catapult structure on a small rise behind the reception building, and intensified further when I get up close.

It is huge. Like a set of rugby goals but much, much bigger. There are two 20m poles on either side and thick elastic ropes - or bungees - strung between them. Soon, Duncan and his friend David Yates, who designed the slingshot, are pulling on these ropes as if their life depends on it. It dawns on me that mine does.

They attach a device like a giant set of scales you'd suspend your luggage on to weigh it. It tells them how much tension is in the bungee; how much weight it will cope with. I'm relieved to see a figure of around 118kg; fully clothed I'm barely 80kg. Duncan tells me this is a test which will be carried out every single day of the slingshot's use. He knows safety is paramount, that Laggan cannot afford a single accident.

Next, I'm asked to step into a safety harness. It's pulled up over the thighs and strapped tight around the groin. More straps go over the shoulder and they're similarly tensioned to the point of only just being able to breathe. "Tight is good", Duncan assures me.

At this point - and maybe a bit late - I wonder out loud what kind of forces my body is about to be subjected to. I'm told that the gravitational force will be anything between 3g and 6g, the acceleration unlike anything I have ever experienced. In a fraction of a second I could be flying at up to 70mph.

Professional pride and personal stubborn-ness prevent me from saying I have made a terrible mistake and can I please go home.

Next I'm given a helmet and a neck brace. My harness is clipped to the bungee rope and the clips screwed tightly shut. I am very firmly attached and that, says Duncan, is why they're calling it a slingshot and not a catapult. "A catapult lets go and this doesn't", he laughs. I hope he's right because now we are heading for the launch.

A Land Rover pulls me back until I'm lying more or less prone, but 6ft in the air. My arms are out front, each hand grasping the bungee. Behind me I have to cross my ankles with another rope in between. It is the one they'll grab to get me back down. I feel like a turkey trussed for the Christmas oven.

The adrenaline is coursing as the Land Rover pulls me back further to the launch point. This varies according to age, body weight and, for want of a better word, how "hard" you are. They're starting me at 20m to see how I cope.

I give a nod when asked if I'm ready and Duncan starts the countdown. Three......two.....one......then a click as the rope is released followed immediately by an involuntary expletive from me as I'm propelled forward at the most incredible velocity.

Duncan is right. I have never experienced such acceleration. It is an amazing experience. It takes only a second or two for the bungee to reach it's outermost extremity (above a field of wholly unconcerned sheep) and then it's wheechin' me back towards the Land Rover - and then out again - and then back - and then out....

Eventually the momentum slows and Duncan grabs the rope and pulls me back to earth. For filming purposes I repeat this process from the 20m three times and it gets more enjoyable each time, even though I now know what to expect.

Finally, it's suggested I go for the "big one". This time the Land Rover pulls me back 30m, which I'm told will pretty much double the g forces and acceleration.

It does, and any further words from me would hardly do it justice. It is quite simply exhilarating.