Russian design from the 1930’s
Guillemots and gannets do it. Cormorants and kingfishers do it. Even the tiny insect-eating dipper does it. And if a plan by the Pentagon’s Defense Advanced Research Projects Agency (DARPA) succeeds, a remarkable airplane may one day do it too: plunge beneath the waves to stalk its prey, before re-emerging to fly home.
The DARPA plan…calls for a stealthy aircraft that can fly low over the sea until it nears its target, which could be an enemy ship, or a coastal site such as a port. It will then alight on the water and transform itself into a submarine that will cruise under water to within striking distance, all without alerting defences…
The challenges are huge, not least because planes and submarines are normally poles apart. Aircraft must be as light as possible to minimise the engine power they need to get airborne. Submarines are heavyweights with massive hulls strong enough to resist crushing forces from the surrounding water. Aircraft use lift from their wings to stay aloft, while submarines operate like underwater balloons, adjusting their buoyancy to sink or rise. So how can engineers balance the conflicting demands? Could a craft be designed to dive into the sea like a gannet? And how will it be propelled – is a jet engine the best solution, both above and below the waves?
According to Norman Polmar, former adviser on naval strategy and technology to the US government, the starting point must be to find a way to make an aircraft that can sink in water. “Submarines cannot fly,” he says, “but seaplanes can submerge…”
“What the Americans want sounds incredibly ambitious,” says UK Royal Navy commander Jonty Powis, head of NATO’s submarine rescue service. “If they achieve half of what they want from this machine they will be doing well.” Others are more optimistic, especially in the light of advances in engineering and materials science since the last attempt – notably in lightweight carbon fibre composites and energy-dense batteries.
RTFA. Learn how much time, effort and money can be spent on designing something useful in 1945 – at the latest.
Tough enough trying to move bodies like the Pentagon to modern Fourth Generation warfare. Giving them sandbox time to play with more archaic concepts only encouraging looking backwards at useless tactics.