Learn about Jonny's jet engines.

Secretly Jonny wants to be a jet fighter pilot one day so he's made his own jet engines to save some time. Jonny can't afford a whole aeroplane so he's had to make do with something smaller.

He started with a jet skateboard (but decided that was too dangerous even for him) and stepped up to a jet scooter.

A cunnning sketch and a few hours in the workshop and Jonny stretched his faithful boyhood toy into a 1 metre long kick scooter with a 3ft jet on it!!!

The jet is a 3ft long pulsejet like the one that was used on a V1 flying bomb from world war 2. It runs on propane. It glows red from end to end when it's running.

Jonny's neighbours get worried when he starts it in the garden, understandably because it's very loud.

Jonny also holds the record for Brunel University's most dangerous project - ever. He is very proud of this title and will defend it until his dying day.

See it run here (5Mb avi file)

Jonny rode the scooter one day and found out how foolish it was to put no brakes on it.

How to build a rocket hovercraft "As seen on TV"

Some of you wanted to know how to make Jonny's rocket hovercraft. It’ll take about 2-3 hours to make. Here's how:

You will need one 8x4 sheet of MDF 3/4" thick, a petrol leaf blower, a sheet of thick polythene about 6ft square and a large CO2 fire extinguisher with a horn. You will also need plenty of mastic and wood screws.

1. Cut the MDF sheet in half so you have two squares. Now mark and cut them so you have two 4ft circles and take the sharp edges off the top and the bottom of each. This is the shape of the hovercraft and it's nearly flat. In exactly the same place on each sheet about 12" from the front cut a 4" hole to match the outlet of the leaf blower. Round the edge of one of the holes and this is going to be the bottom sheet on the hovercraft.

2. Lay the polythene sheet out on a flat surface and gently lower the bottom sheet of MDF onto it with the rounded edge of the hole facing the polythene. Cut the polythene around the edge of the MDF leaving 6-8" to fold over the top. Run a very thick bead of mastic around the top edge of the board.

3. Now carefully fold the polythene over the mastic bead and staple it down just to secure it. Don’t pull it too tight, it wants to be just a little loose. Take time and pleat it around the curved front and back.

4. When finished run another bead of mastic around the 4” hole, lay the other MDF board on top so the two 4” holes line up and screw it tightly down.

5. Flip it over so the polythene faces up. Make another circle about 8” diameter but out of ¼” MDF or ply. This mounts onto the polythene in the centre of the hovercraft. Screw it on securely using plenty of mastic to seal it. The polythene inflates around this board to make a kind of foot.

6. Draw a circle about 2” out from the disc in the centre and cut out 10 one-inch holes from the polythene. This is where the leaf-blower air is going to escape.

7. Carefully flip it back over and mount the leaf blower over the 4” hole so it’s air tight. It’s a good idea to stick a few runs of gaffer tape around the edge to protect the polythene.

8. Mount the CO2 fire extinguisher so the horn points backwards and this is your CO2 rocket. Slow but sure.

9. To start the hovercraft, lift the front up and start the leaf blower. Lower it back down and it should be hovering. Note: it will only work on a smooth surface.

10. Don’t forget you’ve got no brakes!