13 Wind Machines From 1978
by Sabri Sansoy
As i was cleaning out my garage I found an old issue of Popular Science dated September 1978. The cover story was entitled “Winners or losers? Energy Experts evaluate 13 wind machines” and depicted a concept that looked like a flattened airplane wing with a giant tail, flanked by two propellors.
The article was written by Victor Chase and illustrated by Ray Pioch and covered 13 wind research projects sponsored by the advanced wind-concepts program at the Department of Energy (DOE). (Permission to use the illustrations is still pending from the editor)
I had just started my own clean energy company and was curious about what happened to these projects after 30 years! I tried contacting the author and the individual project managers listed in the article, and got a hold of 3 people: Dr. Peter Moretti, DOE project manager that oversaw these 13 projects, Dale Whitford of the Maderas Project, and Dr. Pasquale Sforza who engineered the vortex augmenter depicted on the cover.
Dr. Peter Moretti stated that all the projects generally failed not because they couldn’t generate power but because the weren’t cost effective. The bigger the size the bigger gravity became a problem. The vortex augmenter had to be an enormous size to generate decent power, the weight/cost of the structure defeated the benefit of any wind energy extraction.
People ignored mechanical issues like vibrations which would cause nuts and bolts to shear off. One project used a belt driven system that used flat belts in a grooved channel. He stated the flat belt was always climbing out of the groove, causing alot of problems. At the time everybody was looking at constant velocity rotors with variable winds. He stated what needed to be done was to use inverters coupled with variable speed devices. He also saw flapping devices and large mechanisms that used sails that would get torn apart in big winds. Rotary motion tends to beat linear motion.
Load duration curves only allows for wind to be 15% of the grid so to make these systems cost effective he stated they needed to be offgrid. Cost of blade manufacturing also needed to come down to be competitive.
Dr. Moretti also talked briefly about the testing side of wind turbines. RockyFlats was looking for a new use so they built a wind turbine testing facility. Unfortunately, Rockyflats has long periods of no wind and short periods of destructive winds that would tear apart the wind prototypes.
So that was my conversation with the original DOE program manager, and here are the 13 designs, which fall into one of the following four categories: vertical axis, augmenter, low cost, and “far-out”.
VERTICAL AXIS WINDMILLS
DARRIEUS – Sandia National Laboratory
Egg beater design invented by G.J.M. Darreus and patented in 1931.
Pros
would spin no matter what the direction the wind came from aerodynamic blades will stall in high winds saving the machine delivers mechanical power to base of shaft, allowing heavy equipment to sit on ground.
Cons
Not self starting.
runs at lower rpm, requiring more costly transmissions.
lower aerodynamic efficiency compared to others.
CYCLOGYRO – Pinson Energy Corp & Aerospace Systems, Inc. Straight, variable-pitch blades designed by Herman Drees, president of Pinson.
Three 8 foot blades at 12 feet diameter produced 2Kw / 24mph & 4Kw / 30mph winds
Awarded $365,000 to develop a one-kilowatt version.
McDonnell Douglas had been developing something similar called the Gyromill
Pros
Self Starting
Control of pitch permits extraction of greater amount of power.
Blades cheaper to manufacture
Cons
no mention in article.
CIRCULATION CONTROLLED – West Virginia University’s Department of Aerospace Engineering
Developed by Dr. Richard Walters
same basic configuration as Cyclogyro but blades use a Short Takeoff & Landing (STOL) circulation controlled wing design.
Using a compressor, high pressure air is blown around the rounded trailing edge, essentially simulating a virtual wing flap.
This causes more lift, hence power at lower optimal speeds.
Pros
Lower centrifugal forces results in lower structural loads.
40-60% efficiency at half the operating speed of a conventional vertical axis machine. Darrieus gets 20-40%, standard horizontals get 40-45%.
Cons
Some power is required to run the compressor, which pressurizes the hollow shaft. The compressed air then would be run thru the struts, thru the blades and out the trailing edges.
note: Dr. Walters feels tradeoff will be worthwhile.
AUGMENTERS
DIFFUSER AUGMENTER – Richard Ohman of Grumman Aerospace Corp. Bethpage, N.Y.
The concept of shrouding a horizontal axis wind turbine is over a 100 years old. The design creates a pressure drop behind the rotor blades, causing increased flow through the propellor. The problem is that the airstream tends to break up as it passes thru the diffuser(shroud), reducing efficiency. At the time, Grumman were trying to optimize the design using modern fluid-dynamic techniques. Their design included slots in the diffuser to introduce external air into the internal wall of the diffuser, reducing the ability to stall. Their wind tunnel tests showed they can squeeze about 3 1/2 times the power from a conventional sized wind turbine. Manufacturing costs seemed to be the bigger issue at the time.
DYNAMIC INDUCER – Dr. Peter B.S. Lissaman, Aeroenvironment, Inc. Pasadena CA.
T-shaped devices are appended to each rotor blade of a conventional horizontal axis machine. These devices pushes air away from the propellor, causing more air to be sucked in thus increasing efficiency. According to Lissaman, if one were to “take the duct and join the propellor to it, then cut slices out of the duct and throw away the pieces not attached to the propellor, he would have these little tip vanes on the propellor.”
His argument is that you only need 1/100th of the “dynamic” duct to do the same amount of work as a static full duct. He draws the analogy between a small airplane wing and a helicopter rotor which is 1/100th the size of the airplane wing to do the same lift.
The problem is that the tip inducers increase drag so the challenge is to minimize this drag. This was first conceived by Professor Theodore Van Holten at the Delft Instituteof Technonology in Holland. At the time a kit was available by Kedco Wind machines. The Kedco is a 3 bladed 12′ diameter system and was rated for 1200watts in a 21mph wind. In his testing Dr. Lissaman wasn’t able to prove the Kedco as practical, yet remained hopeful.
VORTEX AUGMENTER – Dr. Pasquale Sforza, Professor of Aerospace Engineering at Polytechnic Institute of NY.
A researcher on aircraft wakes, Dr. Sforza idea was to capture the kinetic energy flying off the wing tips as wingtip vortices. His concept was to mount two rotors on a delta wing. As the air passes over the wing, vortices are formed thus concentrating the wind energy before it reaches the rotor. According to Dr. Sforza, you can almost double the wind velocity.
He constructed a prototype having a delta wing 18′ in length and 10′ long, a vertical tail for yaw, and two 3ft diameter rotors. he stated he was very pleased with the results. You can derive more energy from smaller rotors. The wind speed to the rotors can be varied by altering angle of attack of wing or by controlling a small flap on the back wing surface. The need for variable pitch motor is eliminated (cost reduction). yaw control is achieved with the vertical tail.
I reached out to Dr. Sforza and here’s the email he sent me about the project:
“Thanks for your interest in an old story. Yes, we moved the device into the
field test stage in the late 1970s but the changing support picture for
energy research in 1980 put an end to further studies. The device is
effective, but there is the tradeoff of a large active surface (the rotor
blades) for a large passive surface (the delta wing) and the economic
advantage is not always clear. However, I had worked with architects where
incorporating the vortex augmenter into the building structure as a (fixed)
roof results in striking buildings and good performance if there is a
prevailing wind direction, as in the case of island applications, especially
since fuel tends to be even more expensive in those locations.”
With best wishes,
Dr. Pasquale M. Sforza
Professor of Mechanical and Aerospace Engineering
University of Florida
TORNADO WIND TURBINE – Dr. James Yen, Grumman Aerospace Bethpage, NY.
His concept consists of a tower with operable vertical vents. The vents on the side toward the wind would open while those opposite would close. As the wind blows into the tower it would spiral toward the top, creating a miniature tornado or vortex. In the center of the vortex is a low pressure area, which would cause outside air to be sucked in through openings around the base of the tower. As this air is sucked in to fill the low pressure void it would drive rotor blades located at the bottom of the tower. His claim is that he augment the power of the wind by a factor of 1000. The concept evidently work with the major issues being cost and efficiency.
LOW COST WINDMILLS
BEARINGLESS ROTOR – Dr. Pam Spierings of United Technologies Research Center, East Hartford Connecticut
Attached to a horizontal axis turbine is a flexible rotor with a pendulum attached to help it bend to the desirable pitch. The section between the hub and the base attachment of the rotor is made of a highly flexible composite. The concept was evidently tested on two helicopter rotor systems. The geometry was key to creating perfect pitch. At the time of this article they had recieved a grant to build an 8Kw bearingless rotor, eliminating the need for pitch control (reducing cost).
BICYCLE WHEEL – Tom Chalk, American Wind Turbine Company, Nebraska
Dr. Dennis McLaughlin of Oklahoma State University bought a 15′ diameter American Wind Turbine and modified it to work to a 30′ design, using 96 stainless steel wire spokes which support 48 airfoils that were 10ft long. Their test results concluded in the design not being viable.
FAR OUT WINDMILLS
ELECTROFLUID DYNAMIC (EFD) – ALVIN MARKS, President of Marks Polarized Corp, Whitestone NY
Using no moving parts, an EFD basically creates energy from wind using a technology similar to lightning in a thunderstorm. “The charged raindrops accumulate in a cloud and form an electric field. When it becomes strong enough you get lightning. What i did was bottle this whole phenomenon”. In wind tunnel tests he produced 1/10th of a watt and believes he can get 450watts in a 22mph wind for each square meter of the device.
Basically, wind is used to help water droplets overcome the static repulsion of moving between two vertically charged grids.
Mark explains “What we do is inject charged droplets into the windstream. The charge is eventually carried away by the wind the the electrical ground, but it has to climb a potentialhill to get to the ground. The load is placed between the collector grid and the ground.” Mark was planning on creating the water droplets by using small water jets which would be shot thru an electric field.
Dr. John Minardi of the University of Dayton, OH is also working on a similar prototype for DOE. He was looking at using liquid hydrogen for cooling moist air to produce small liquid droplets that can be passed through a corona discharge.
HUMID AIR – Dr. Thomas Oliver, South Dakota School of Mines & Technology, Rapid City
1/3 of of solar energy reaching earth goes into evaporating moisture. To tap into this energy his first concept was to construct a natural draft tower “in which humid air would be brought in from the bottom. The wet air, being lighter than dry air, would rise and would expand, causing its temperature to drop. The cooler air would give off water and the latent heat in the humid air would be given off to the now drier air. The warmer air would have increased bouyancy and would continue to rise up the tower, passing a wind turbine on its way out. The real problem was that he would need to construct a 10000 foot tower.
His second concept reduced the height of the tower by mechanizing the expansion-compression cycle. However, this used too much energy.
As of this article he was working on a 3rd concept which was a vortex flow device, in which “one machine would accomplish both expansion and compression of the air. The humid air would enter on the upper end of the expansion chamber, spiraling down to a low pressure area where it would be cooled by a water spray, then go on to a compression chamber. A rotor would be placed in the flow to extract the energy.
MADERAS MOTOR – Julius Maderas, inventor & Dale Whitford of the University of Dayton
Described as a train to nowhere, the idea, invented in 1920, consisted of a circular train track with a train of flat cars, each with one revolving vertical cylinder. Each cylinder was revolved with their own electric motor. The train moves forward because of the coriolis force created between the interaction of the wind and revolving cylinders. Generators are located at the wheels of each flat car to generate power, which is taken off a third rail, similar to a conventional electric train but in reverse”. A prototype was built in 1933 but the project was ended due to cheap fuel. Dale Whitford had resurrected the project for DOE at this writing.
I called Dale Whitford and he was kind enough to talk with me about this project. He stated that the final report entitled “An Analysis of the Madaras Power Project” was filed with the DOE in June 1978 and was probably available in their archives. Dr. Whitford stated that the project was one nondiscriminate method of extracting energy from large amounts of wind. Through wind tunnel testing and structural design analyses they optimized size, weight & costs models and showed a lot of promise.
Since the cylinders were mounted on a circular track they would have to stop twice and rotate in the other direction as they moved along the track. Winged systems were studied but required high wind speeds. Rotating cylinders ,using Magnus Effect, can operate at much lower speeds and producer about 13-14 times more load than a conventional wing.
He stated the ideal location for a fullscale Madaras Project would be in the southeast corner of Wyoming.
Dr. Whitford also stated his father built a proof of concept that was 90′ high and 22ft wide.
LIFT TRANSLATOR – Dr. Daniel Schneider
The concept consists of a series of airfoils attached to a vertically mounted conveyor belt. The airfoils on one side would be pushed up by the wind while the airfoils on the other side are pushed down. The system didn’t need yaw control because it worked with wind coming from a variety of directions. A 45 foot version was built at the University of Texas in Dallas, which ran for 9 months and generated up to 15 Kilowatts of power.