The unmanned aircraft system (UAS) Part one: Not a drone

-August 26, 2013

I recently had a discussion with Alfredo Ramirez, director and chief architect of High Altitude Long Endurance (HALE) Systems Integrated Product Team (IPT), for Northrop Grumman Aerospace Systems. My initial idea was to discuss “drones” with him, when I found out that although “drones” is a popular term used for unmanned aircraft, Ramirez’ team prefers to refer to them as unmanned aircraft systems. I found out the difference between the two and learned a great deal of respect for this type of aircraft design family known as the UAS, especially in the electronics aspects of the design. You will see that the modern UAS is far from a “dumb” drone remotely piloted with a joystick.

Part one of this multi-part article will introduce the near-autonomous UAS. Part two will continue with great details of the on-board electronics, guidance and communications systems. Our third part will feature a commercial “drone” teardown.


Ramirez, with more than 25 years of aerospace engineering in the UAS area, gave me a little background to put his present “masterpiece”, the “Global Hawk”, in perspective.

A low continuous humming sound, that’s the definition of the word “drone”. That might have been the case 20 years ago, but today’s modern military drones can run pretty silent; commercial drones may still meet the humming sound definition.

In 1916, Professor Archibald Low designed a WWI “drone”, but it was unsuccessful and the British Army cancelled the project. He was also developing radio-control for his designs.

An early “drone” designed by Professor Low was a monoplane made of wood and tin (Image courtesy of Michael Drape)

Remotely Piloted Vehicles (RPVs) got their start in WWII performing information gathering with a film camera

The mid-70s tested many types of systems but electronics was not really there yet. More progress in the 80s as electronics began to mature with semiconductors.

The UAS enters the scene

The early 90s saw the beginning of the first Gulf War and in 1994 Ramirez formed part of the team that started the conceptual system design for DARPA’s Tier 2 Plus HALE UAS program. The successful program capture led to the development of the RQ-4 system. Ramirez’ first Global Hawk design drawing can be seen in Figure 1.


Figure 1: The first Global Hawk design done by Ramirez shows the glider-like extended wings and large jet engine/power plant (Image courtesy of Northrup Grumman)

Next: Global Hawk

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