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After the Phantom Eye landed, it was slightly damaged when the landing gear hit the lakebed and broke

Boeing sent its Phantom Eye unmanned airborne system (UAS) on its first autonomous flight last week.

Boeing's Phantom Eye is a hydrogen-powered unmanned aerial vehicle (UAV) that is propeller-driven. The aircraft uses two 2.3 liter, four-cylinder engines capable of pushing 300 horsepower total and can loiter above a target for up to 10 days. Its main purpose is to gather information or conduct attack missions.

The Phantom Eye took off at 6:22 a.m. PST for a 28-minute flight. It reached an altitude of 4,080 feet and a speed of 62 knots. The flight took place June 1 at NASA's Dryden Flight Research Center at Edwards Air Force Base in California.

"This day ushers in a new era of persistent Intelligence, Surveillance and Reconnaisance (ISR) where an unmanned aircraft will remain on station for days at a time providing critical information and services," said Darryl Davis, president of Boeing Phantom Works. "This flight puts Boeing on a path to accomplish another aerospace first -- the capability of four days of unrefueled, autonomous flight."

After the Phantom Eye landed, it was slightly damaged when the landing gear hit the lakebed and broke. But overall, the flight was a success.

Previous to the June 1 flight, the Phantom Eye took part in a series of tests throughout April, such as navigation and control, pilot interface, and mission planning.

The Phantom Eye used for demonstration purposes has a 150-foot wingspan and can carry a 450-pound payload. It can fly up to 96 hours without needing to land, but Boeing is looking to make a new model in 2014 that can fly up to 240 hours without landing.




Source: Boeing



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RE: Hydrogen?
By Samus on 6/6/2012 1:47:09 AM , Rating: 3
I find the choice of engine configuration more unusual than the choice of fuel. A prop configuration demands high RPM, not torque, which is why inline and V-configuration engines were terrible in world war-era planes. Since we looked to the auto industry at the time it was what we had to fight with, but was no competition for the Japanese which could fly nearly twice as far on the same amount of fuel.

Radial and rotary engines are probably better suited for this application as they produce a higher RPM in less displacement at the expense of torque, likely increasing fuel efficiency. But I'm not an engineer at Boeing, and I'm sure they know what they're doing...I just find it interesting why they're doing it this way.


RE: Hydrogen?
By AssBall on 6/6/2012 6:44:54 AM , Rating: 2
I was thinking radial too, but then again they can get 20k RPM out of a Honda motorcycle, so i don't know either.


RE: Hydrogen?
By 91TTZ on 6/8/2012 10:27:36 AM , Rating: 2
You're thinking about this backwards. Airplane engines favor low-rpm operation, not high RPM operation.


RE: Hydrogen?
By Amiga500 on 6/6/2012 8:06:50 AM , Rating: 2
The need for rpm depends on your propeller pitch (and span).

Ideally (from an aerodynamic point of view), you'll turn a larger blade slower.


RE: Hydrogen?
By 91TTZ on 6/8/2012 10:26:41 AM , Rating: 2
quote:
I find the choice of engine configuration more unusual than the choice of fuel. A prop configuration demands high RPM, not torque, which is why inline and V-configuration engines were terrible in world war-era planes.


I think you have that backwards. Prop aircraft don't require high RPM. Piston aviation engines usually turn at a much lower RPM than automotive engines. People that use automotive engine conversions on their homebuilt aircraft often have to use a speed-reducing gearbox so the prop doesn't turn at full crankshaft speed. This increases the weight of the aircraft.

A popular 4 cylinder aircraft engine like the O-320 produces 160 HP at 2700 RPM.

And rotary engines like the Wankel are very inefficient, so fuel efficiency would be horrible. For instance, a Mazda RX-8 gets slightly worse highway fuel economy than a larger, heavier Corvette Z06 with the 7 liter V8.


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