NASA wind turbines
In 1975 NASA designed and built its first prototype wind turbine, the 100 kW Mod-0 in Sandusky Ohio, with funding from the National Science Foundation and ERDA.
This 1957 unit designed by Johannes Juul generated 200 kW for 11 years, and used a three-bladed upwind rotor with a lattice tower and blades supported partly by internal guy wires.
NASA research and prototypes demonstrated that there were considerable scaling challenges in structural strength, fatigue, speed control, and aerodynamics.
Studies carried out by NASA's contractors suggested that much larger units would be required, on the order of 1 MW or more, for economic production of electricity by utilities.
This design had a 38-metre diameter downwind two-bladed rotor, coupled to a synchronous generator, with a power rating of 100 kW at 8 m/s wind speed.
An investigation revealed that unexpectedly high cyclic loads were the result of a significant blockage of the wind by the complex truss tower structure.
The Danish da:Vindkraftværket Tvindkraft with a hub height of 46 meters above the ground, a larger rotor and a rating at a higher wind speed, had a capacity of 2000 kW but never achieved 2 MW power output of the Mod-1.
The Mod-1's design weight prevented it from becoming a competitive commercial product, but a prototype was installed and run at Howard's Knob near Boone, North Carolina.
Low-frequency noise from the heavy truss tower blocking the wind to the downwind rotor caused problems to residences located close by.
In 1977 Boeing won the NASA and US-DOE contract for the design, fabrication, construction, installation and testing of several 2.5-megawatt wind turbine models in the United States.
The Goodnoe Hills site was primarily a research project for Boeing, Bonneville Power Administration, NASA and the Battelle Memorial Institute.
It featured a "soft" steel tube tower, fiberglass blades, torsional springs and dashpots in the drivetrain, and a flexible teetered hub.
Early in 1988, operation of the turbine was transferred to Hawaiian Electric Industries, then to the Makani Uwila Power Corporations (MUPC), and kept in service intermittently until late in 1996.
Because of financial difficulties, the wind turbine was shut down, along with the rest of MUPC, and passed to the property owner, Campbell Estates.
[13] None of the NASA prototypes became commonly produced as commercial generators because the purpose of the program was to develop the technology and support the emerging industry.
Many of the technologies such as doubly fed variable speed generators, light weight tubular towers, and the engineering design tools used in the wind industry today were developed and pioneered by the NASA program.
[16] General Electric, Boeing Engineering and Construction, Westinghouse and United Technologies were the commercial partners on the program, some of whom are involved in the wind industry today.
The commercial sales of the NASA/Boeing Mod-5B, for example, came to an end in 1987 when Boeing Engineering and Construction announced they were "planning to leave the market because low oil prices are keeping windmills for electricity generation uneconomical.
