LONDON-The dust sheets have finally been thrown off the world’s longest aircraft in the UK’s largest hanger.

The monster vehicle- part plane, part airship and part helicopter - was today unveiled in all its 300ft (91m) long glory.

That makes it almost as long as Big Ben is high, and 60ft (18m) longer than the biggest airliners, the Airbus A380 and Boeing 747-8. It is also almost 30ft (8m) longer than the airlift cargo aircraft Antonov An-225, which was until now the longest aircraft ever built. Known as the HAV304, the giant aircraft is being displayed at Cardington in Bedfordshire in the only hangar big enough to accommodate the 113ft (34m) wide and 85ft (26m) high beast. Bruce Dickinson, lead singer of Iron Maiden and a high-profile investor in the aircraft, compared the ship to Thunderbird 2 and described it as a ‘game changer.’ ‘It will be able to cross the Atlantic and launch things right where they need to be,’ he told Radio 4’s Today programme. ‘It can reach about 100mph and stay airborne for about three-and-a-half weeks.’ The low carbon ship, known as the HAV304, doesn’t require a runway to take off.

 and is thought to be about 70 per cent more environmentally friendly than a cargo plane. It is due to fly in the UK later this year and is designed to stay airborne for up to three weeks to help with activities such as surveillance, communications and delivering aid. Created by Hybrid Air Vehicles and first flown in the U.S, the ultra-green HAV304 project has just received a £2.5 million grant from the UK government.

It looks like giant airship but it has a unique aerodynamic shape that means it can also create lift just like an aeroplane wing. The cambered shape provides up to 40 per cent of the vehicle’s lift.

This allowed engineers make the machine heavier than air, removing the need for crew to hang onto ropes to hold it down.  A number of ballonets fore and aft in each of the hulls provide pressure control. The aircraft is powered by four 350 hp, four litre V8 direct injection, turbocharged diesel engines. Two engines mounted forward on the hull and two on the stern of the hull for cruise operation. The plan is that the HAV304 will eventually lead to the development of the Airlander 50, which would be able to transport 50 tonnes of freight.