12 noon, June 2nd - Hornchurch Airfield. Six members of H.A.R.T. gathered to fly various rockets.

But the one to go up first was Laurie’s special Merlin 4.

This rocket is a strengthened Zinger powered by a Aerotech E25 engine.

A special experiment. The computer simulation had registered a top speed of Mach 1.4 and so we all waited for the launch with excitement and trepidation

The countdown began and finished then the launch button was pressed and.... nothing! A big fat nothing!

The Merlin 4 was checked and nothing was wrong so the ignition system was checked and we found out that the batteries had fallen loose in the battery bay.

H.A.R.T. members rallied round and supplied Laurie with another 12 Volt ignition system.

The system was tested with a igniter on it’s own and it fired. This time it was going to go.....

5...4...3...2...1...Lift Off... virtually straight away we all became victims of the sonic boom as the rocket smashed it’s way through the sound barrier just split seconds from lift off.

This was the rockets goal and it had achieved it. The video shows just one frame of blur and the computer simulation estimated a acceleration of 88G!! I don’t doubt it. My ears were ringing from the sound of the gunshot noise and Laurie had a smile from ear to ear.

As I looked up it was apparent the rocket was in trouble as it only achieved half of it’s expected height. Still 1500 feet is quite reasonable for a rocket with half it’s wings ripped off.

The tremendous G-force had buckled part of the upper body tube and the balsa wings had just ripped away from the body tube.

At least the engine mount and wing roots had been reinforced and so it had stubby wings left on it.

The streamer was last seen heading into the woods.

Laurie ran over and picked up the pieces. Even the transfers had been pulled off. As the rest of the members came over smiling and patting Laurie’s back - he was still trying to stop shaking with the excitement of breaking the Sound Barrier.

The Merlin 4’s primary objective was achieved and the H.A.R.T. Group had become one of the few model rocket clubs to break the sound barrier.

There are not many things made at home that travel under it’s own power at over 1000 M.P.H. - it’s the thing which makes rocketry great !!!