Unmanned Future

How small drones can revolutionise warfare once battery life is improved. An extract

David Hamling

There is an old, pre-smartphone-era joke about a man who meets his inventor friend carrying two suitcases down the street. The inventor shows off the wristwatch he has built, which as well as indicating the time anywhere in the world, also shows the tides, phases of the moon, and position of the stars. His friend is duly impressed. The only problem, says the inventor picking up the suitcases, is the size of the batteries.

That about describes the present situation of small drones. What they do is great; the only problem is the batteries. Whatever small drones can do, they cannot do it for long because of their limited battery life. The smallest only fly for ten minutes or so. Quadrotors may manage half an hour, and the Raven, our gold standard for capability, keeps flying for about ninety minutes.

The situation is better the larger the drone. The RQ-20 Puma, the Raven’s big brother with twice the wingspan and three times the weight, has an endurance of three hours. Scaling means that, other things being equal, bigger drones carry proportionately more batteries or fuel.

Switching from battery power to liquid fuel extends the range of small drones dramatically. In 2003, a drone weighing eleven pounds with a wingspan of six feet flew across the Atlantic, from Cape Spear in Newfoundland to Mannin Beach in Ireland. The drone, known as TAM 5, took thirty-eight hours to make a crossing of almost two thousand miles, at a steady speed of around fifty miles an hour. Small drones can cross oceans and continents.

Unfortunately, the internal combustion engine has disadvantages. For one thing, it is very noisy; this was one of the flaws that sunk the RQ-16 T-Hawk. It cannot sneak up and take pictures without being spotted.

A drone with a combustion engine is more vulnerable to being shot at, and when it crashes, there is a safety hazard. Those falling apart landings, or running into a wall, become less hilarious. And the logistical issues—having to keep stores of drone fuel and drone oil, servicing and maintaining the engine—make it more complex and less attractive than the battery-powered alternative.

On the face of it, small drones are doomed to perpetual disadvantage compared to their larger cousins. The Raven cannot match a Predator’s ability to orbit over a target area for twenty four hours or more, and the Raven is confined to a small area. With current technology, a Raven could in theory fly out thirty miles, take a picture, and then return to