"There are those that see JSF as the last manned fighter. I'm one that's inclined to believe that."
-- Adm. Michael Mullen, chairman of the Joint Chiefs of Staff

"The solution to future threats is not something that has a pilot in it."
-- Defense Secretary Robert Gates

But what, a defense investor may ask, is the solution? The companies that have made the greatest inroads in development of unmanned aerial vehicles -- Northrop Grumman (NYSE: NOC), Boeing (NYSE: BA), and Textron (NYSE: TXT) -- will tell you that the future lies in remotely piloted flight. I agree. 

By and large, UAVs are:

And since a pilot flying a plane without actually being in the plane is considerably less likely to get shot down behind enemy lines, risking capture or death, or requiring search-and-rescue missions to avert same, UAVs trail a shorter logistical "tail" than their manned counterparts. Less fuel to haul. Fewer SAR teams to maintain. Generally -- a smaller footprint.

Such advantages are fueling a renaissance in the UAV field, as company after company reports better and better products to choose from. Here are just a few of the developments that have taken place in UAVS since last we checked in.

Military time
The Navy and Marines' joint effort to replace Boeing's venerable ScanEagle with a new product got a little closer to completion in May. More than a dozen firms are vying for $450 million to produce an initial run of UAVs for the STUAS/Tier II contract. Leading contenders remain Textron and its Aerosonde Mk, Boeing and the Integrator, Raytheon (NYSE: RTN) with the KillerBee-4, and the UAV Dynamics Storm, built jointly by General Dynamics (NYSE: GD) and Elbit Systems. The program's manager suggested the Navy is "very close" to awarding a contract -- but that was two months ago, and no word yet on how far out the goalposts may have moved.

Anchors away!
Not content with just one project on the back burner, though, the Navy is pushing ahead with at least two more. General Atomics is working to create a carrier-landing-capable UAV based on its jet-powered Predator C drone. The new UAV, dubbed the "Sea Avenger," will compete with Northrop's X-47B for the Navy's unmanned carrier-launched airborne surveillance and strike contract. Meanwhile, Northrop is upgrading its own capabilities in the field of helicopter-based UAVs by allying with Textron's Bell Helicopter to create the Fire-X -- an upgrade of its already popular Fire Scout offering.

Yet for all their popularity with the armed forces, there remains one thing that today's UAVs cannot do. They can't dogfight other UAVs or manned jets. They cannot win a nation true air superiority.

Yet.

Bogeys at 12 o'clock high
This could change. In recent weeks, we've seen multiple developments in pursuit of the holy grail of UAV-building -- a fully functional, full-size, dogfight-capable UAV. Over at Boeing, the company took a first, halting step in that direction in May, claiming a $70 million contract from the Air Force to begin work converting six Lockheed Martin (NYSE: LMT) built F-16 manned fighter jets into QF-16 unmanned drones.

Of course, as fighters go, the QF-16 will be more a punching bag than a puncher (USAF plans to use the things as flying, remote-controlled targets to shoot at). But Boeing is also working up something a bit more robust, in the form of its super-secret Phantom Ray. Little is known about the bird at this time, save that it's going to have about a 15-meter wingspan and may weigh a little under four tons, empty. As such, even the Phantom Ray is unlikely to replace the need for manned fighter jets patrolling American skies. What, an investor may wonder, will it take to finally make the leap in scale?

Size matters
To me, it's a question of size. Right now, even the biggest low-altitude UAVs in service, General Atomics' Predator and Warrior, aren't equipped to carry Sidewinder missiles. They can carry smaller Stingers, however, which are almost as fast as the Sidewinder, and fast enough to catch many of the Soviet-era jets at close quarters.

Meanwhile, the new Taranis UAV that BAE Systems is developing over in England (with help from Rolls-Royce, QinetiQ and General Electric (NYSE: GE)), may be big enough to carry heavier ordnance. Weighing in at a reported eight tons and standing more than 10 feet tall, the Taranis is roughly the size of a Harrier jump jet, and so can probably carry equivalent ordnance, such as AMRAAM medium air-to-air missiles and short-range Sidewinders -- making it the first truly capable robotic fighter jet.

3, 2, 1, contact!
If that's the way the U.K. is headed, don't think for a minute the U.S. won't follow suit. Already, we hear that DARPA is seeking to develop fully capable unmanned versions of the A-10, F-4 Phantom, and F-16 Falcon within two to three years.

It's a brave new world out there, Fools. Invest in it.

General Dynamics is a Motley Fool Inside Value selection, but Fool contributor Rich Smith does not own shares of any company named above. The Motley Fool has a disclosure policy.