A Hampstead actor’s daring attempt to set a new altitude world record has got off the ground despite a major set-back – he is too heavy to fly the aircraft.

Ham & High: Rob Rackstraw with the Ikarus microlightRob Rackstraw with the Ikarus microlight (Image: Archant)

Amateur pilot Rob Rackstraw, the voice of countless cartoon characters in hit children’s TV shows such as Bob the Builder and Octonauts, was leading an amibitious plan to soar to 25,000ft in a mini plane known as a microlight.

The lightweight two-seater aircrafts are usually flown at under 5,000ft – and it is illegal to take them above 10,000ft in the UK.

But Mr Rackstraw’s hopes of smashing the previous record of flying at 24,000ft were dashed when he realised the microlight plane would never get that high with him on board.

The 47-year-old, of Holly Bush Vale, who weighs just under 13st, said: “It was a bit galling to realise that I was going to be too heavy.

“I’m skinny as a rake, but I’m still going to be too heavy to do it.

“I’m gutted, but I would much rather someone else got in the plane and we broke the record.”

He will now support two lighter pilots who are making the attempt – in a plane named the Ikarus C42.In honour of the mythical Icarus, the four-man team will fly two microlights to the Greek island of Crete – which Icarus was attempting to escape when he flew too close to the sun.

“You could not think of a more unlikely name for an aeroplane, but the German makers of the Ikarus decided this would be a good idea,” said Mr Rackstraw.

The team set off on the 2,500 mile trip yesterday and will take four or five days to reach Crete. The record attempt is due to take place next Wednesday.

“The highest I have flown is 5,000ft and the furthest I have gone is Reading and back,” said Mr Rackstraw. “It’s a bit of a step up.

“It’s not something you do lightly. Nobody has flown this aeroplane anything like that high.”

The group is promoting awareness of the charity Aerobility, which offers disabled people the chance to fly planes.

However, they are unlikely to raise any money for the cause.

“The truth is, we’re not going to break even,” he said.

“It’s just a mad plan in the great tradition of British people doing daft things.”