Sunraycer—The GM Solar-Powered Car

Solar Challenge race tests new technology–Carol Hazard

Hughes News Special Edition for Australia, September 1987

Transcribed by Faith MacPherson

 

A Hughes team is developing the power system for a solar-powered car that General Motors has entered in the 1987 Solar Challenge race in Australia.

The race, which is scheduled to being Nov. 1, will cover 1950 miles in the outback from Darwin to Adelaide.

GM’s entry is one of 25 vehicles representing nine countries that have been entered. Howard Wilson, Hughes vice president in charge of GM projects, is overall project manager for the company’s participation.

According to Ervin Adler, project manager for Space and Communications Group’s work on the car, the end result may spawn a new age of electric-powered commuter vehicles and demonstrate innovative approaches for using solar power on Earth.

The Group team assigned to the out-of-the-ordinary project is modifying technology that it has used for decades to power spacecraft. It will apply its expertise in solar cells, solar panels, and batteries to build an efficient power source for the vehicle.

Based on a mandated daily schedule from 8 a.m. to 5 p.m. and depending upon weather conditions, the race is expected to last no longer than seven days. Any vehicle lagging behind the lead by two full day will be disqualified.

Without disclosing details, Mr. Adler said that GM’s entry is “larger than a compact car, ultra-lightweight, and highly streamlined.”

According to the rules, the vehicle cannot be taller or wider than 6 ½ feet and no longer than 19 ½ feet.

“Anything goes, as long as it complies with the rules,” said Mr. Adler.

The project must be completed by October to allow for transportation to Australia.

“With so little time left, we’ll have to push to get it done,” said Mr. Adler. “It’s a challenge, but it’s also fun.”

GM is providing electric drive and suspension systems, aerodynamic testing, and design consultation for the vehicle through several organizations.

Other team members, Group Lotus PLC of London and Holden’s Motor Company of Australia, both GM international subsidiaries, are developing race strategy and logistics support.

AeroVironment, Inc., of Monrovia, Calif., has been retained by GM to contribute its expertise in lightweight structures and materials, low-speed aerodynamics, and low-powered aircraft.

AeroVironment designed and built the Gossamer Condor, the first maneuverable human-powered aircraft, and the Solar Challenger, a solar powered aircraft that set records in its crossing of the English Channel.

Hughes News Quarterly International July-September, 1987

Sunraycer Description and Race Results—Jack Fisher

The Challenge

Early in 1987 GM’s Australian Division contacted GM headquarters in Detroit to inquire about the corporation’s interest in participating in the Pentax World Solar Challenge to be held in Australia later that year. Roger Smith, GM CEO at the that time, was interested and a team was formed, consisting of GM, Hughes Aircraft, and AeroVironment, to design a solar-powered car that came to be called the Sunraycer. Time was of the essence as only about 10 months remained to design, build and test the car.

The race was to begin on November 1 and was to cover a distance of about 1900 miles on the Stuart Highway between Darwin in Australia’s Northern Territory and Adelaide in South Australia. This two-lane highway is only partially paved. The cars are to be solar powered with the solar panel area limited to 8 m ²(projected area). Any size battery can be used but must be charged only by the solar panel. Racing will take place daily between 8 am and 5 pm with maintenance and battery charging allowed from 6am to 8 am and 5 pm to 7 pm. Six drivers plus an unlimited support team are allowed for each car with the drivers ballasted to 85 kg. A major concern on the Stuart Highway was the presence of large tractor-trailers, known locally as road trains. Each participating car had to undergo a stability test passing a tractor-trailer driving in the opposite direction at 100 km/hr.

Car Design

The design approach adopted was to minimize weight, aerodynamic drag and rolling friction. This necessitated a solar panel that was contoured to the shape of the car rather than a flat panel that could be raised to face the sun while racing. The contoured panel, however would be raised to face the sun during the two daily battery charging opportunities. The car body, only 3.3 feet in height, was a lightweight honeycomb composite over an aluminum tube frame that in wind tunnel tests had a drag coefficient of only 0.125 based on the frontal area.

Two cars were built—a development model with silicon solar cells that provided an output of 1000 watts and the racing model with a combination of silicon (20%) and gallium-arsenide (80%) cells that provided 1400 watts. The silver zinc battery had a capacity of 3-kilowatt hours. The solar panels and battery were both designed and built by Hughes SCG.

The controls consisted of a throttle, brakes and a two-mode cruise control operating at a fixed speed or fixed battery current. An option for regenerative braking returning energy to the battery was also provided. A lightweight dc brushless 2 horsepower electric motor operating at 92% efficiency provided torque to a chain drive on the left rear wheel. The car weight (without driver) was only 385 pounds. GM did not disclose the cost for the Sunraycer development, but it is estimated to be in the order of $2 million.

Software

Software was developed at SCG to simulate racing conditions and predict vehicle performance. This software, developed on a Macintosh personal computer, by Joe Gurley and Mike Cassidy was also used during the race for tactical support. An SCG systems engineer, probably Mike Cassidy, traveled with the support team in Australia to provide tactical support for race operations using this software.

The software provided an electrical system simulation that took into account ambient conditions including rolling friction, aerodynamic drag, sun angle, wind, and grade to provide an optimal speed control law. This allowed the determination taking into account the diurnal variation of the solar aspect angle a minimum and maximum operating speed. In the early morning and late afternoon the minimum speed could be maintained using the battery while during midday holding the speed to the maximum allowed battery charging.

Testing

A ¼-scale model was tested in Caltech’s GALCIT wind tunnel and the full-scale development model was tested in a GM wind tunnel. The development model was operated for 3000 miles at GM’s Mesa Proving Ground in Arizona. As a result of this testing the suspension system was redesigned. The race vehicle was completed only a few days before shipment to Australia and underwent only limited testing.

Race Results

The Sunraycer won the pole position for the start of the race with a speed of 33 mph and completed the race in 44 hr 54 min at an average speed of 42.8 mph almost 24 hr ahead of second place car. The only problems encountered during the race were three flat tires. In June 1988 at the GM proving ground in Arizona the Sunraycer set a new world speed record of 48.7 mph for a solar powered land vehicle. GM donated the car to the Smithsonian where it is on permanent display at the Museum of American History.

 

 

New nickel-hydrogen battery to give spacecraft longer life Hughes News Quarterly International January-March 1986 Transcribed by Faith MacPherson

More than a decade of research and development in a battery that is expected to add years of life to spacecraft is ready for harvest.

New lines of Space and Communications Group satellites will be powered by nickel hydrogen (Ni-H₂) batteries, a hybrid that may outlive and outperform its predecessors.

By combining the nickel electrode from the commonly used nickel-cadmium batteries (Ni-Cd) with the hydrogen electrode from hydrogen-oxygen fuel cells, Hughes scientists have developed a battery that in its eighth year of real-time testing, has shown no signs of significant degradation.

“Compared with the 10-year life span of nickel cadmiums, we expect to get 15, possibly 20 years or more out of nickel hydrogens,” said senior scientist Howard Rogers of Space and Communications Group’s Power Sources department.

Dr. Rogers was hired by Hughes in 1973 to work on the development of Ni-H₂ batteries, an electrochemical system that was first suggested in 1961 by Frank Ludwig, who is now a senior scientist at Electro-Optical and Data Systems Group. Much of the development work has been sponsored by the Air Force.

The ongoing effort has produced a battery that will serve the high-power needs of the large, new spacecraft generation, such as the Intelsat VI series and the HS 393 family.

Batteries breathe life into satellites, storing energy that is collected in spacecraft solar cell arrays and providing full power during eclipses of the sun when solar-generated electricity is temporarily unavailable.

Although both Ni-H₂ and Ni-Cd batteries can power a spacecraft, the Ni-H₂ unit weighs less, a critical factor in determining space-bound payloads.

The beauty of the Ni-H₂ battery, said Dr. Rogers, is that it has the rechargeable quality of Ni-Cd batteries, but few of its disadvantages, such as high susceptibility to damage from electrical and thermal environments.

“Nickel-hydrogen batteries require less care and feeding than nickel cadmium, and are less likely to be damaged by unintentional abuse,” said Dr. Rogers.

Contained in pressurized containers, Ni- H₂ batteries do not bulge from pressure that builds up if one of the cells is completely discharged, a possible occurrence in Ni-Cd batteries. They also do not run the risk of severe damage from over-charging.

Another advantage is that, unlike Ni-Cd batteries, the amount of electricity stored in Ni-H₂ batteries can be monitored. “With a nickel cadmium, you can estimate the state of charge if you know how much electricity the battery should hold and its rate of discharge. But there’s no way to know for sure,” said Dr. Rogers.

The change in a Ni- H₂ battery can be assessed precisely by using a gauge that measures hydrogen pressure levels.

“Although a nickel-hydrogen cell can be discharged to 100 per cent of its capacity without adverse effects, the discharge limit has been set at 80 per cent to achieve at least a 10-year life,” said Dr. Rogers.

“The nickel-hydrogen battery, in its life test at the 80 per cent level,” he continued, “has been ‘cycled’ again and again, drained of its energy and recharged repeatedly many thousands of times without any significant decrease in performance.”

 

The Magellan Mission–Hughes News Quarterly International April-June, 1989

Magellan up; on 15-month trip to Venus—Keith Bass

The Space Shuttle Atlantis roared away from its launch pad and into space Thursday, May 4. Its near-perfect launch, after an aborted launch attempt six days earlier, marked a rebirth of interplanetary exploration for the United States.

This flight of the shuttle had one main purpose: to send off Magellan, a spacecraft carrying a Hughes-built radar that is now on a mission to map the Earth’s sister planet, Venus.

Magellan is the first U. S. interplanetary probe in 11 years and the first to be launched by the shuttle. Its successful launch fulfilled NASA’s hopes for a return of stability to interplanetary projects since the Challenger disaster of 1986.

Soon after launch, space agency officials reported that Magellan’s course is to accurate that only a few normal correction maneuvers will be required during the craft’s 15-month trip to Venus.

Magellan is now cruising at about 6000 mph and will travel 795 million miles to reach Venus in August of 1990.

Once there, Magellan will use its Hughes-built radar during 1852 orbits to send back the most detailed images to date of the Venusian surface—a desolate, alien landscape that is perpetually shrouded by layers of dense, poisonous clouds.

Magellan also will relay to Earth information on the chemical composition of Venus, and observation of the craft from Earth will be used to help elicit information about the planet’s gravity.

After giving Magellan a successful send-off, and before their safe return to Earth, the Atlantis crew conducted a few experiments to determine if large, perfect crystals of certain semiconductors could be grown is space. The crew also photographed lightning in support of a project that could lead to better weather prediction, and the shuttles’s thrusters were fired over Hawaii to help the Air Force test an optical tracking system for rockets.

Scientists believe that observations of Venus—and of other planets—enable them to make better conclusions about the origins of Earth and firmer predictions about where planet Earth is headed.

Radar technique key to mission—Bill Andrews

Mapping a planet millions of miles away is no easy task.

It’s hard enough designing and building a complex spacecraft such as Magellan that can leave the Earth, survive a trip across the solar system, and find its way to another celestial rock. In this case, the craft must then settle into a proper orbit and operate automatically by commands from Earth.

Getting to the planet and acquiring orbit are actually well within the technical abilities of NASA, the Jet Propulsion Laboratory, and Hughes Space and Communications Group.

Sometimes the subtle challenges are the toughest to meet. Take radar mapping for example. In order to map the whole planet, the radar signals sent to and received from the planet’s surface by the orbiting spacecraft must be finely tailored.

Radar Systems Group’s Howard Nussbaum, chief scientist in Advance Programs Division and senior member of the RSG team that assisted on the Magellan program, explained the problem of controlling the Synthetic Aperture Radar (SAR) in such a dynamic environment.

“Depending upon the angle of the orbit, which is highly elliptical, the power of the returning signal can vary. When the spacecraft is close to the planet, the radar reception is clearer, so to speak.”

“But if the spacecraft is some distance from Venus, the returning signal is not as strong,” Dr. Nussbaum said. “Therefore, the ‘look’ angle must be adjusted to compensate for the weaker return.”

These altitude variations present a situation somewhat analogous to attempting to take a series of photographs of an object while the camera shifts between close-up and long-distance positions, requiring continuous refocusing.

To compensate for this phenomenon, RSG wrote radar mapping sequence software for the SAR.

The software modifies the mapping sequence instructions that control the signal transmitted by the radar and reception process. The instructions vary according to the predicted orbit of the spacecraft and are used for a three-day period. This ensures a radar return signal that will provide a quality image.

After each three-hour mapping orbit, radar data is transmitted to Earth through the Deep Space Network with stations at Goldstone, Calif., Madrid, Spain, and Canberra, Australia. Upon receipt at JPL, the data is processed to form images. Quality images verify that the mapping sequences devised many days earlier have provided proper planet coverage.

$40 Million Contract Won by S&CG for Trio of Maritime Satellites Hughes New June 8, 1973

Space and Communications Group will build three synchronous satellites for the Navy and maritime industry under a $40 million contract awarded by the Communications Satellite Corporation.

The contract calls for three multi-frequency spacecraft, each with a five-year lifetime design. One satellite will be placed over the Atlantic, one over the Pacific, and the third will be held in reserve.

The system, Comsat reported, is to begin service by the fall of 1974. Each of the satellites will be capable of providing a variety of communication services, including voice, teletype, facsimile, and high-speed data transmission.

Les Gustafson, a veteran member of the Hughes space team, has been named program manager. Dave Braverman is the manager of systems engineering.

The program has been assigned to the Commercial Satellite Systems Division under Manager Harold Rosen.

Surveyor, Not Yet Ready To Fly, Learning to Land Hughes News June 8, 1962 transcribed by Faith Macpherson

Takes Jolts in Stride

The Surveyor spacecraft, not yet ready to fly, already is learning to land – and under conditions equivalent to those expected to be found on the moon.

Since nobody has ever been on the moon’s surface, to man’s knowledge anyway, Surveyor is being given the worst of it in the tests designed to verify the design concept of the spacecraft’s landing gear. It is being dropped on to “moon rocks,” into “moon dust,” and slammed in to a simulated lunar surface on one, two and three legs with the impact down slope, up slope and on a side slope.

Significantly, Surveyor or rather a full-scale prototype space frame laden with dummy components, has passed a dozen tests to date with nothing more than aching “feet” for all its rough landings.

How do you create a lunar environment, particularly since no one has been there? It wasn’t easy, but available scientific knowledge and HAC’s engineering ingenuity were enough to provide a reasonable facsimile of what can be expected on the moon.

One of the greatest problems to overcome was that the moon’s gravitational pull is only one-sixth that on earth. To make the tests realistic, it was necessary to develop a device which would reduce the spacecraft’s weight by five-sixths, yet leave its total mass unchanged. That is, the device must be relatively massless, yet provide a lifting force which remains constant and vertical regardless of the vehicle’s horizontal or vertical motion.

In order to provide that part of the device which produces the constant lifting force independent of vertical motion, a technique used in aircraft drop testing to simulate wing lift was chosen. Two towering pneumatic cylinders provide just the right amount of weight reduction without changing the Surveyor’s mass. The device is then operated in conjunction with a special pulley system to simulate the moon’s gravity.

Irwin Baker, head of the Structures Section, Engineering Mechanics and Preliminary Design Department, Space Systems Division, designed the special pulley system which has a unique feature that maintains the constant vertical force even when the spacecraft is moved laterally.

Smooth or Rough

The simulated lunar surface can be made just as smooth or miserably rough as the need demands. For example, blocks of wood simulate “moon rocks.” The angle of the “lunar surface” can be varied to provide different angles for the spacecraft prototype to land on.

In addition, the horizontal and vertical velocity of impact can be controlled and varied so that almost every conceivable way of landing can be tested before Surveyor makes its actual landing on the real moon.

To obtain data on the rigid body behavior of the spacecraft and landing loads imposed on the spaceframe, the spacecraft is instrumented with a multitude of accelerometers and strain gauges. Oscillographs and tapes record the information from the instruments. Additional information is obtained from high-speed motion picture camera coverage.

Have the rugged tests proved anything? Most significantly they have proved that Ralph Dietrick, project engineer in charge of the landing gear design, was correct in his pre-test analysis.

Using a high-speed digital computer, Mr. Deitrick made an extensive study of the rigid body behavior of spacecraft under various lunar landing conditions. To date, the drop tests have shown good correlation with his original analysis.

Designed Test Site

Dick Harvuot, in charge of the High Temperature Structures Test Laboratory, at the Rodeo Rd. facility, where the Surveyor drop test facility also is located, designed and supervised construction of the entire test site.

It’s apparent he doesn’t think the moon’s surface is a bed of roses. But as is the case with most American space projects, realistic testing before launch has resulted in successful missions.

Regardless of what Surveyor finds on the moon, it’s unlikely that landing will be any more difficult that its prototype is now experiencing on Rodeo Rd.