If you are searching for a solution do you ask the experts or the crowd? Challenge prizes take innovation outside the research establishment - and they are getting more popular.
On 12 June 1979, a scraggly Californian fitness buff, Bryan Allen, found himself hovering a foot or so above the English Channel in a box wrapped in polyester film, pedalling frantically.
He was competing to become the first person to fly under his own power across the world's busiest shipping lane.
