What goes up does not necessarily come down...

Steve Bennett, an amateur rocket builder, was yesterday searching for his latest missile after it roared into the clouds and vanished.

A signal from the 10-foot Lexx rocket abruptly stopped and there was no sign of it floating back to earth on its built-in parachute over the Cheviot Hills in Northumberland. On top of that, Mr Bennett's hope of breaking the sound barrier appeared to have been dashed as he listened in vain for a tell-tale sonic boom.

But Mr Bennett, 33, was not disappointed. "I am remaining optimistic," he said as he stood in rain driven by a fierce wind over 1,000 feet up on the Otterburn Army Ranges.

"The conditions were really poor with all this rain and wind and there was a point when I was afraid it might not leave the ground today, so it was a big relief when it did go.

"As far as I am concerned it has at least been a 50 per cent successful exercise.

"If we get the rest of the rocket back it will have been 100 per cent successful. As for whether we reached the height and speed hoped for, we won't know until we get the vehicle back and analyse the data from it."

Problems including short circuits meant the countdown was repeated five times before the rocket hurtled into the cloud base and out of sight.

Until Mr Bennett and his six-year-old son Max can find it and check the data from its instruments its performance will remain a mystery.

He was not too surprised that observers had not seen the rocket parachuting back down to the ground, "as in this wind it would have drifted, so it could be coming down four miles to the north-west".

The flight was a test of the top stage of a planned 22-foot rocket - his biggest yet - which he hopes to launch in about six weeks. "It will be full steam ahead with the three-stage vehicle, which we are going to send up three miles, hopefully before the end of March."

Mr Bennett expects it eventually to reach altitudes of 15 miles. The world record for an amateur launch is 10 miles. "We're still on target for April; there was nothing wrong with the motor. This is the run-up to our getting a satellite into space by the new millennium."

Mr Bennett is sponsored by Lexx, a science-fiction television series due for release this year.

He is also working with the University of Salford, testing engine power, computer software and parachute mechanisms. He has spent 20 years building some of the world's largest amateur rockets.