With the increased demand for electrical generating sources due to such items as Mode C transponders in ARSAs and TCA "veils", there is renewed interest in the wind driven generator. At this time, there only appears to be one firm that is producing a wind driven generator for aircraft use. The contact is Ron Cox, President, Basic Aircraft Products, Inc., 6700 NW 22nd St., Margate, FL 33063. Ron's story of development of the air driven alternator is typical of the air craftsman who is also an experimenter. Ron is working on a Supplemental Type Certificate for the Aeronca aircraft and plans to pursue STC's for Taylorcraft and other classic aircraft in the future. This item is an air driven alternator which is planned to be a primary electrical source. There is another version designed as a backup version in case of failure of the primary electrical source. The usual question when this type of electrical source is discussed is, "how much drag does it cause and what affect does it have on aircraft performance?" Comparative performance for the Aeronca model is shown in Tables 1 and 2. You will recognize that a regulator is required to regulate the DC voltage output from an alternator and in the case of this wind driven generator, the regulator regulates slightlv below 14 volt DC output. The current or amperage available varies with the airspeed on this particular unit as shown in Table 3. As expected with increasing airspeed, the current output of the alternator goes up, while the regulator regulates the voltage output to the required volts. The flight tests that Ron
Cox has accomplished are necessary for an experimental amateur built aircraft but could be done to determine current output at various rpm in a homebuilt installation. Classic aircraft would require the alternator to have a supplemental type certificate before installation. The Aeronca's 7 and 11 aircraft model is depicted in the photo shown. The model 1008 is 6" in diameter, 10" high with mount, 8" long and weighs about 5 Ibs. It is designed for a maximum airspeed of 120 mph and maximum altitude of 10,000 ft. The diagram shows the usual wiring from the alternator through the main bus. Some of the interesting details of the alternator are that you can preflight it by simply checking the rotation which should spin freely. Normal operation of the alternator includes moderate starting torque and magnetic cogging. The alternator should begin rotation at approximately 1600 rpm engine speed. It is necessary to maintain a minimal electrical load on taxi out and run up. A normal load can be carried in takeoff and cruise. In normal use this wind driven generator should require no maintenance. RELAY
AIRCRAFT COMPARATIVE CRUISE PERFORMANCE
Aircraft cruise performance without and with the alternator installed Altitude
Airspeed
Average Engine RPM
2000 Ft. 2000 Ft. 2000 Ft.
70 mph 80 mph 90 mph
W/O Alt 2000 rpm 2085 rpm
With Alt 1970 rpm 2110 rpm
2240 rpm
2230 rpm
ALTERNATOR DIAGRAM
Table 1 FLIGHT PERFORMANCE CHARACTERISTICS
AIRCRAFT COMPARATIVE STALL PERFORMANCE
Aircraft stall performance without and with the alternator installed
