Lighter than air
Dorrington’s airship is basically an oversized helium balloon, carrying researchers suspended below it in a gondola as they skim over the treetops, propelled by electric motors.
Helium is the second lightest gas after hydrogen (a no-no for modern airships because of its high flammability). By displacing the much denser air around it, the helium-filled envelope makes the airship buoyant. Every kilo of load the ship needs to carry requires a cubic metre of helium to keep it up in the air.
‘It’s a constant battle against weight. Making very small airships is very difficult: you put something on board to make the airship better, but that makes it heavier,’ explains Dorrington, ‘you have to question every gram.’
Dorrington’s latest airship was held aloft by a sizeable 500 cubic metres of helium, making it somewhat awkward to manoeuvre. ‘When flying a rainforest airship, the key thing is not flying quickly, but flying with control so you can take samples,’ he says. The aerodynamics of the ship therefore need to be closely scrutinised.
Dendronautics - A bird's eye view of rainforests http://www.dendronautics.com
for more on Helium...
Nottingham University's indepth look at He http://www.periodicvideos.com/videos/002.htm