Wind Generators

June 2007
Updated March 2018

[This is kind of a two-part posting.  The first is one of Harry Fenton's responses to a question about wind-powered generators for aircraft power. The second half is my own smart-xxx response. :-) ]

Note:  About ten years after this posting, Ian Cameron came up with a reasonable solution.  See "How to Electrify a Fly Baby."

From the Harry Fenton on Small Continental Engines Page:

I came up with an idea - I'm sure not original - about using a motorcycle alternator strung under the fuselage. There are some expensive "aircraft" systems, but I bet I can make something with the motorcycle alt and a small quality prop attached.  I saw today that they make 30-40 amp motorcycle alternators and full kits with regulators, etc.,. I know a guy who put one in a HAPI VW case and it powers everything he needs (COM, mode-c) with only 10amps.

Ever see anyone do this? I figure I could test it driving in the car with a volt/amp meter and light. After attaching, I could create a nice fiberglass cover to dress it up and channel the air.


You mean something like this?

Yeah, another idea that has been done through the years.  A couple of basic problems with wind driven alternators- drag and consistent voltage output through the airframe speed range.

Typically, the alternator is tuned for max output when in cruise.  However, when the airplane is at pattern speed, the alternator has no output as it is turning too slowly.

Drag is an issue, too.  The alternator has to be a pretty good size and the prop can provide a lot of drag.  I had a torpedo shaped wind driven alternator on my old Stinson 105 and it cut the airspeed by 5mph and made a pretty loud whirring noise when it ran.

If you start searching on the internet, you will find that there have been quite a number of home brewed wind driven alternators.  I figure that they are a less than complete solution because I don't see all that many installed on planes at airshows like Sun n Fun and Oshkosh.  There is a certain validation of ideas via numbers..

My solution to electrics has been a battery and a trickle charger.  A motorcycle sized battery will run most electrics for a days worth of flying and then can be charged overnight via a charge.  Just run a quick disconnect umbilical cord between the battery and the charger.


Ron's Follow-up

With the radio, transponder, strobe, and lights on my Fly Baby, I've finally found a wind-driven generator that'll produce enough power:

This generator is from 1918, it was used in WWI aircraft to provide power for the primitive radios used for artillery spotting.  Looks like if I hooked the 'ol gel cell to it, I could probably eke out another mile or so to an engine-out glide.  The generator is on display at the American Radio Museum in Bellingham, Washington.

My favorite old-radio flying story from this period happened not too long after the Great War.  Omar Locklear, soon to become Hollywood's most famous wing-walker, was the radio operator on a DH-4 on a training mission.  The radios used long trailing aerials with weights at the end.

When Locklear threw out his aerial, the weight flew back and snagged in the rigging for the tail surfaces.  While the pilot kept the plane steady, Locklear crawled out of the cockpit, slid back on the turtledeck, unwrapped the aerial from the tail, flung it free, then climbed back forward and back into his station.  He pulled on his headphones and copied a morse-code message from his squadron commander:


Ron Wanttaja

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