[BITList] Interesting!

[John Feltham]

A Silent Electric Plane

An electric plane that cruises silently at 70 mph and costs just 70  
cents to charge
By Amanda Schupak
Posted 12.04.2008 at 12:54 pm
12 Comments



Happy Landings: The builder says his goal was a noiseless plane
that would fly as smoothly as a magic carpet.  John B. Carnett

In August, at the Experimental Aircraft Association (EAA) AirVenture  
show in Oshkosh, Wisconsin, Randall Fishman's ElectraFlyer-C made a  
virtually silent pass over the audience at a mere 200 feet. What they  
were seeing (but not hearing) might be the world's first fully  
electric-powered airplane—representing, said one EAA official, "a  
groundbreaking technology that would be aviation's first true  
alternative to a fossil-fuel engine. Fishman, a retired jeweler from  
New Jersey, has been flying planes and gliders for 30 years. In the  
mid-1990s, he put together a motorized glider kit, but it was noisy  
and undependable. It sat in storage until two years ago, when he  
replaced its gas engine with an 18-horsepower electric motor he and a  
colleague designed to minimize noise and vibration. He then raised the  
plane body eight inches off the ground to accommodate a 45-inch  
propeller, increasing the prop's thrust by more than half. He also  
designed battery packs to hold two 75-volt lithium-ion-polymer  
batteries, which can juice up in midair and propel the plane at 70  
miles an hour for 90 minutes on a single charge.Now Fishman is taking  
his creation to the public. He sells kits on his Web site  
(electraflyer.com) that include the batteries and electrical  
propulsion components. By mid-2010, he plans to offer ready-to-fly  
electric two-seat planes.

How the ElectraFlyer-C Works

The pilot's view of the cockpit controls.:  John B. Carnett

Motor Controller Located behind the propeller (along with the motor  
and one of the battery packs), the computerized controller loses only  
2 percent of the energy that passes through it from the batteries to  
the motor, contributing to an overall efficiency of 88 percent (a  
comparable two-stroke gas engine operates with about 15 percent  
efficiency).

Regenerative Motor Flipping a switch in the cockpit turns the  
propeller into a wind-powered generator, converting its motion into  
electricity. While cruising, the propeller spins up to 2,400 rpm,  
charging the lithium-ion-polymer batteries mid-flight.

Digital Gauges The voltmeter tracks how much juice is left. (Fishman  
suggests landing if you get down to 60 volts.) Underneath that, the  
ammeter shows how fast the battery is being sapped. In regenerative  
mode, a minus sign indicates that the propeller is pumping energy back  
in.


Propeller motion charges the batteries:  John B. Carnett

Propeller Fishman's original propeller revved between 5,000 and 6,000  
rpm, making a terrible racket. The larger (45-inch) direct-drive prop  
spins at 3,100 rpm at full power and goes easy on the ears.

Battery Packs For safety, the batteries are surrounded by fireproof  
ceramic and a thin layer of stainless steel. It takes six hours to  
charge the pack and costs Fishman just 70 cents on his electric bill.


Runway Project: The ElectraFlyer-C won Randall Fishman the
EAA's coveted August Raspet award for design.





ooroo

If you don't hear the knock of opportunity - build a door.

Anon.



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