DAVID GREENE, HOST:

Now if you own an electric car, like say the Nissan Leaf, and you use an electric vehicle charger, well, here's something you might not know. That charger may have been made by the same company that makes drones - the unmanned aircraft used by our military. The company is called AeroVironment. It's based outside Los Angeles.

It is a firm with a strange combination of specialties. And NPR's Amy Walters says that has a lot to do with its creator.

AMY WALTERS, BYLINE: Paul MacCready loved things that fly.

PAUL MACCREADY: As a youngster, I was very interested in model airplanes, ornithopters, autogyros, helicopters, gliders, power planes...

WALTERS: MacCready passed away in 2007. That was from a speech he made at a TED conference in 2003. But as obsessed as he was with flying things, MacCready never wanted to break the sound barrier like Chuck Yaeger or buzz the control tower like Maverick in "Top Gun".

He loved nature, and MacCready's dream was to create - birds - or recreate them. He founded AeroVironment in 1971. His designs were very light and flew incredibly slow with just enough power to stay aloft. But passion and interest don't always make money. And MacCready found himself in debt, to the tune of $100,000.

MACCREADY: And I noticed that the Kremer prize for human-powered flight was 50,000 pounds, which at the exchange rate was just about $100,000, so suddenly I was interested in human-powered flight.

WALTERS: The result was the Gossamer Condor.

(SOUNDBITE OF CROWD CHATTER)

UNIDENTIFIED MAN #1: The only obstacle left is the 10-foot finish poll.

(SOUNDBITE OF CHEERS)

WALTERS: A pilot peddled MacCready's ultra light plane - through the air.

(SOUNDBITE OF CROWD CHATTER AND CHEERS)

WALTERS: Paul MacCready won the prize. That first human-powered plane led to solar-powered planes; the planes led to cars. But, the evolution was far from linear.

UNIDENTIFIED MAN #2: Ready.

UNIDENTIFIED MAN #3: Launching.

WALTERS: Enter the Raven, an AeroVironment drone.

(SOUNDBITE OF MOTOR REVVING)

WALTERS: That's what you're hearing right now. You'll notice the company's fondness for ornithological nomenclature. Sergeant Michael Sustad trained on the Raven in Afghanistan. It's so small you can launch it with your bare hand.

SERGEANT MICHAEL SUSTAD: It has cameras, GPS, so that when it comes back, we can brief our commanders what's going on at that location.

ROGER KHOUREY: You might want to stand back because I'm about to plug the charge cable in.

WALTERS: Rodger Khourey is a senior electronics engineer with AeroVironment in California.

KHOUREY: the sound it will make will be a high pitch, whining - it sound like somebody's whistling to a dog.

WALTERS: Khourey is testing AeroVironment's other specialty - electric vehicle charging stations made to line U.S. highways. The difference between his company's products doesn't escape him.

KHOUREY: One flies the other doesn't.

WALTERS: The core technologies are the same though, and that means engineering staff can move from one side of the company to the other. And Department of Defense contracts pick of the tab for all kinds of new research and development, including the Switchblade, the first hand held drone that spies, and shoots.

When production began, Tim Conver, the company's current president - says he had to sit the staff down for a little talk.

TIM CONVER: And I think a lot of individuals that initially taken aback - what are we doing making weapons systems? - either got comfortable with it or, in some cases said, you know, I'm not really, I don't want to work on that program. I'm fine with us doing it, but I don't want to work on it myself. No problem.

WALTERS: When I asked Conver if the company had drifted from its beginnings, he said no.

CONVER: I understand that it's conventional wisdom that you have defense and you've got environment here, but as you can see, I don't see any inherent conflict.

WALTERS: Drones make up over three quarters of AeroVironment's revenue and the industry is moving at a quick pace with over four percent growth projected over the next 10 years.

The future of AeroVironment's Electrical vehicle charger business is less predictable. That will depend on U.S. demand for electric cars.

Amy Walters, NPR News. Transcript provided by NPR, Copyright NPR.