It is an unlikely scene. On a wet and windy day in Largs, huddled together in a converted stable block, a band of dedicated rocket enthusiasts are debating the merits of water-jet propulsion.

Every now and then the rain lets up. Immediately this strange group quit their conversations, and dash out into the wide open space of Kelburn country park to fire their rockets into the cloudy sky. Then, driven by whatever strange spirit possesses them, they begin monitoring speed, distance and trajectory, scratching their findings into notebooks.

Such are the goings-on at the command centre of International Rocket Week (IRW), the highlight of the rocketeers’ calendar, where men, and the occasional woman, meet to discuss their hobby and check out the latest developments in amateur space-vehicle design.

The event is organised by John Bonsor, the rocket fiend and founder member of the United Kingdom Rocket Association. Bonsor, who lives in Ayrshire, has been building rockets since he was five years old. He can’t remember exactly what inspired him — “I think it was partly to do with a television programme I saw where a monkey was accidentally launched into space, but I can’t be sure” — but it fired a passion that has lasted a lifetime.

Now a full-time rocketeer, Bonsor, 51, travels the country offering workshops about his craft and sharing his encyclopedic — if somewhat arcane — knowledge. For this year’s IRW he has developed an exhibition devoted to the history of rocketry in Scotland, and in particular the achievements of John D Stewart, the founder of the Paisley Rocketeers’ Society, the oldest rocketry group in the world, who died in March.

Among the exhibits are prototype rockets invented by Stewart to assist in mail delivery and aerial photography. “Stewart was a pioneer and his work was a significant design breakthrough in the history of space flight,” says Bonsor. “Rocketry as a hobby is great fun, but amateur rocketeers still contribute a significant amount to scientific advancement in the area.”

But setting aside the worthy benefits of scientific advancement, many rocketeers regard IRW as a social event, a chance to catch up with fellow enthusiasts from countries including Austria, France, Germany and Holland. This year, several families have made the trip, undeterred by the weather or the sodden campsite where they are staying. Such is the power of bonding among the rocketry community.

“Some people might be under the impression that rocketry is a very lonely hobby,” says Bonsor. “But I have met a great many friends through events such as these. They are not just boys’ toys either: when I do my school workshops it’s often the young girls who show the most interest in the subject.”

Adrian Hurt, a technician at Heriot-Watt University, takes a week off every August to travel to IRW to display his impressive collection of scale models of famous space and rocket craft, past and present. His pride and joy are a scale model of the Thunderbird, a British Army surface-to-air missile, and a newly completed model of SpaceShipOne, which made the first privately funded human space flight in 2004.

Rocketry has developed a highly specialised language of its own. Aficionados talk of shred and chuff, Cato (catastrophically aborted take-off) and hybrid motors. There are even schisms within the group, mostly between the hardcore fuel propellant rocketeers and the water-jet proponents, whose rockets appear to have been fashioned from washing-up liquid bottles.

One of the final events of IRW sees rocket clubs from across Britain compete for the coveted Schwiglhofer trophy in the aquajet team distance event. Until recently the Paisley Rocketeers dominated the event, but last year the Sheffield Rocketry Association wrested it from their grasp. Bonsor is hoping a Scottish team can reclaim the crown. “There would be a few celebrations if that was to happen, we might even crack open a few bottles,” he laughs.

Apparently this is what they refer to as rocket roll.

International Rocket Week is on until tomorrow, Aug 29, at Kelburn castle and country park near Largs

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