With a whoosh of colour and a chorus of `ahhhs’ Johnny Jetpack, a 7ft 6in dummy attached to a giant water rocket backpack, flies 90ft into the air before plummeting to the ground in dramatic fashion. However, `fly’ is not the adjective his creator uses. The Johnny Jetpack Propulsion Laboratory prefers to describe what he does as `attempting to pass on to the heavens and dance upside down in the sky’ – much more appropriate for the kind of events Johnny appears at (recently taking to the skies at a memorial concert for Grateful Dead guitarist Jerry Garcia).
The jetpack, made from two 17l soda bottles, wooden dowels, fibre tape and surgical tubing, is powered by compressed CO2 from 80psi to 120psi.
Although Johnny’s ground staff sometimes tell curious onlookers that the propellant is a mixture of `Anhydrous Hydrazine and fuel oil’, it is in fact nothing more noxious than coloured water.
The jetpack accelerates from 0 to 50mph in about one second, using three gallons of propellant in 0.75s.