At $4 million a pop, the MQ-1 Predator unmanned aircraft might seem like a prime target for cost savings as President Obama's scalpel-yielding team try to prune federal spending.

But despite the space-age technologies—and sky-high price tags—pilotless vehicles often are more economical than their manned counterparts over time, manufacturers said, securing their place in the aerospace industry even as other high-cost projects are dropping like flies.

The Predator, a small-scale reconnaissance drone with weapon capabilities, was the brainchild of San Diego, Calif.-based General Atomics Aeronautical Systems Inc. And while it was not the first pilotless plane to leave the runway, it is perhaps the best-known unmanned aircraft patrolling the skies today, with 34 of them airborne every second of every day worldwide.

Chris Ames, director of business development at General Atomics, said...