RAF engineers are used to working with fast-moving objects.

But a group of friends from RAF Brize Norton are hoping to use their expertise in a slightly different way – by racing their own soapbox.

Peter McCarthy, Andy Jackson, Jon Newman and Matt Nicholas will be taking part in the Red Bull Soapbox Race at London’s Alexandra Gardens on Sunday.

The friends, who are all members of 99 Squadron, entered the race four months ago after spotting an advert online. After getting clearance from their commander to enter the race, they decided to model their soapbox design on the C-17 Globemaster, which the squadron uses.

The military aircraft is used primarily to transport troops and cargo around the world and can carry 13 Land Rovers, a Chinook helicopter or three Apache-sized helicopters. The soapbox has not quite got the same capacity, but the engineers are hoping what it lacks in size it will make up for with speed.

Having had their design chosen by Red Bull as one of the 70 to take part in the race, the group got to work on building their soapbox at RAF Fairford.

Mr McCarthy, 41, of Shilton Park in Carterton, said: “We’ve had great support from everyone in the service.

“The Ministry of Defence has agreed to pay for the vehicle and Boeing are providing transport to London.

“We’ve heard rumours that a Navy team will be entering as well so that should be an interesting battle between us.”

The group is raising money for the Royal Air Forces Association, which supports the families of service personnel.

The foursome have raised £500 so far and have set a target of £1,000 for the charity.

The Red Bull race invites amateur drivers to build and race soapbox vehicles that do not use fuel.

Competitors drive their contraptions down a 430-metre long course featuring ramps and bends, with the winner completing the course in the fastest time.

Previous designs have included a piano, a rodeo clown and a giant corn-on-the-cob. Mr McCarthy, who has been in the RAF for 15 years, said: “It’s been like a rollercoaster ride so far and none of us want to get off.

“But as long as we beat the Navy team we’ll be happy.”

* Visit justgiving.com/99Sqn-RedBull-Team