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Flight Night in Portola Valley

 

Click on pictures to enlarge and see captions.

The first Flight Night Electric Airshow at the Portola Valley Town Center showcased high-tech radio-controlled model planes and helicopters.

A crowd of at least 100 stood on the sidelines of the soccer field on Thursday evening, May 19, as plane owners took turns launching and flying their crafts.

The take-offs and landings tended to be uneventful, unlike the actual flying.

Many craft hovered in front of the crowd, maneuvering in directions impossible for full sized aircraft.

One airplane, for example, hung three feet above the grass with its nose pointed directly down, its propeller rotating in the ordinary way. This plane and the others with wings could also fly upside down with ease and seemingly continuously.

Even the helicopters could fly upside down. There was also at least one helicopter-like flying machine that, with its four rotating propellers and no cockpit, has no counterpart in the full-sized world.

One explanation for the agility (given to a reporter but not in detail) is that air behaves differently in supporting planes of this size. Evidence of this difference is easy to spot in that many of the planes had completely flat wings.

A normal aircraft has wings that are curved on the upper side. This curvature requires the air passing over the top of the wing to travel a longer distance to rejoin the air beneath the wing. The air pressure is thus lower over the wing. The normal air pressure under the wing raises the plane, a phenomenon known as lift.

Model planes apparently don't need a curved wing to create lift.

Comments

Like this comment
Posted by Chris
a resident of another community
on Jun 2, 2011 at 8:14 pm

Actually, a curved wing is not required to create lift.

Try this: while driving your car down the highway, stick your hand out the window, and hold it flat. Rotate it to different angles. At some angles, the wind will want to blow your hand up, at other angles it will blow it down, and at other angles it will blow it backwards. When your hand is being pushed up, you are pushing the wind down.

The wing of a plane is like your hand -- it is moving through the air, pushing some of the air down. The air, in turn, pushes the plane up.

Curved wings happen to be more efficient, just like a curved Prius is more efficient than a pick-up truck. But model planes have very powerful motors, and the fuel (battery power) is cheap -- so we often build inefficient but easy-to-build flat wings than hard-to-build but more efficient curved ones.

If you want to learn more, some references:

An article on lift: Web Link)

An article from NASA explaining why the "curved wing" theory is incorrect: Web Link

A funny comic on the subject: Web Link


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