For over a decade, American defense contractors have dominated the business of building unmanned aerial vehicles -- "drones" in the popular parlance -- for the military. And not just our military. When France wanted to beef up its robotic air force last year, for example, it called General Atomics and ordered a fleet of Reaper drones with a price tag of $1.5 billion.

Australia plans to spend hundreds of millions of its own dollars to acquire MQ-4C Triton drones from Northrop Grumman. Why, even the United Kingdom relies on U.S. drones for air cover in Afghanistan.

However, the U.K. is taking steps to "declare its independence" from America today by building a drone of its own.

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BAE's Taranis. Source: BAE Systems.

Introducing the BAE Taranis
Earlier this year, major U.K. defense contractor BAE Systems (NASDAQOTH:BAESY) let slip a few details about its new combat drone, giving analysts a glimpse at the plane's size and shape, and predicting that when complete, it will be "the most advanced air system [that the U.K. has] ever conceived."

That was about all the British Defense Ministry had to say on the matter, but it was enough to pique the interest of Popular Science, which this month published a report comparing Britain's Taranis to a secret stealth drone being developed by Northrop Grumman -- the RQ-180 (not to be confused with Russia's RD-180).

So what did PopSci learn?

Dueling drones
Working from the few parameters known about these two top top-secret aircraft, PopSci put virtual models of the planes through their paces with help from an aeronautical engineer and specialized flight simulation software. Here's what they came up with:

Metric 

BAE Taranis

Northrop RQ-180

Wingspan

33 feet

130 feet

Length

41 feet

50 feet

Flight time

<6 hours

>7 hours

Top speed

700+ mph

600+ mph

Stealth (on a scale of 1-5)

4

5

Maneuverability
(on a scale of 1-5)

4

3

Both drones are designed as "flying wings," and significantly more "stealthy" than the current generation of military unmanned aerial vehicles. One key difference: PopSci concluded that BAE's Taranis is designed for combat, while the RQ-180 is not.

In theory, Taranis will be faster and more maneuverable than the RQ-180, but also very hard to control. The RQ-180, in contrast, will be a high-flying spy plane, "graceful and easy to fly," according to aeronautical engineer Austin Meyer in PopSci, and able to fly longer than Taranis -- essentially, an invisible (to radar) version of Northrop's Global Hawk.

This all jibes with analyst speculation that the military will use the RQ-180 to perform intelligence, surveillance, and reconnaissance over countries with advanced air defense systems. In a December 2013 article, however, Aviation Week pointed out that the RD-180 grew out of U.S. Air Force efforts to develop a combat drone capable of attacking targets in such environments. This suggests the RQ-180 could be a first step toward Northrop Grumman's bid to win the contract for the Air Force's $55 billion stealthy Long Range Strike Bomber, or LRS-B.

Here's the top secret PopSci didn't tell you
When you get right down to it, how the RQ-180 compares to the Taranis might not be the point at all. This drone's real rivals might be Boeing and Lockheed Martin -- and its real target: beating them both to win LRS-B for Northrop Grumman.

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Shh! Don't tell anyone! This is what the Air Force's new Long Range Strike Bomber might look like. Source: Boeing.

Rich Smith has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.