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It’s fair to say that most if not all folks interested in sport flying (that’s you and me) are interested in what’s happening as far as electric propulsion for aeroplanes is concerned.  However, the truth is “not enough”.  Sure, there are a number of light airplanes flying all-electric, but you’d have to sell your house in order to afford them.  Slightly more promising is the option to replace your trusty gas engine with an electric powerplant – and a few of these are becoming available as turn-key installations.

For example, in conversation with Chip at Aeromarine, he tells me that he will have a plug-and-play electric alternative by the end of the year.  30Kw, 18kg, but no price.  Endurance?  No info either.  Or maybe he was just too busy filling orders to have the time to reply more comprehensively to my questions.

Meanwhile, across at Skyleader (based in the Czech Republic): they offer the following info:

Q: How long is the flight time on one charge?
A: Flight times average 1½ hours per charge at a constant cruising speed.

Q: What type of motor is used in the ElectraFlyer?
A: The motor is a custom built DC 18hp (13.5kw) permanent magnet motor.

Q: What type of batteries are used in the ElectraFlyer?
A: Each battery pack is made up of Lithium-Polymer (LiPo) cells which provide the greatest specific energy density of any battery type. The battery packs come in 3 sizes, from 2.6kwh to 5.6kwh capacities depending on the flying style you may choose.

Q: How much do the batteries weigh?
A: The largest battery pack (5.6kwh) weighs 78 lbs (35.5 kg) including all packaging and wiring.

Mmmm… the equivalent of 18hp at 35.5kg?  90 min on a clean airframe at constant speed?  That probably translates to 45 min on “ordinary” planes under “normal” flying conditions.  I’m not WILD about the numbers.  But they do provide pricing:

BATTERY PACKAGES: select one
  1. Small lithium-polymer pack 2.75kwh $ 4,400.00
  2. Medium lithium-polymer pack 3.3kwh $ 5,200.00
  3. Large lithium-polymer pack  5.6kwh $ 8,500.00
BATTERY CHARGER:
custom high power with lithium ion charge curve-auto shutoff		 $ 895.00
ELECTRAFLYER PROPULSION KIT:
(to build your own trike or add to your ultralight)
Includes: motor, electronic controller, power dial and switch, fuse, connectors, ammeter and shunt, voltmeter, custom machined propeller hub, and digital motor temperature display with probe.		 $ 4,600.00

It looks like for the biggest battery pack, it is going to cost $13,995 USD.  When compared to either the Aeromanine or Hummel v-twin engines ($7,500) producing double the power – I think I’ll pass for now.

According to Denis Carly at Aerolite:
“The complete electric propulsion system, which includes the motor, motor mount, 2 batteries, 2 battery chargers, controller, throttle, cables, etc (everything you need to install and run the system) is $9,750. The complete system with 4 batteries and 4 chargers is $13,950.”

The motor runs off one to four lithium-ion battery packs, each weighing about 35 pounds.  So four batteries will weigh 140lbs (63kg),  Dennis states that “a typical ultralight flight profile, with a full power take off, a reasonable climb and a 40-45 mph cruise will result in about an hour of flight time”.  However, that’s in Part 103 aircraft.  Expect far less in your typical home-built creation.

So where does this leave us?  On the one hand, there is some movement on the R&D side of things, and the first of the plug-and-play electric powerplants are starting to emerge.  The downsides are: at least double the cost, and half the power.

Oh well, it’s fun to dream.