Trippin' on Helios

by: Ruth Ross

How would you like to soar 100,000 feet above the earth, with wind rushing through your hair, on your own wings? You have all the energy of a solar system and all you have to do is enjoy the sun beating on your back. This dream has become a reality with a new generation of airplane. Helios is the name of the most amazing solar powered aircraft ever constructed by man.

The wing plane is a remote-controlled craft. Currently it has a wingspan of 247 feet, a length of 12 feet, and a wing thickness of less than a foot. Structurally, it can carry its empty weight of 1,322 pounds and a payload of up to 726 pounds. The wing plane is designed to reach altitudes around 100,000 feet, and stay in the air for months at a time. This light weight wonder is composed of carbon fiber, graphite epoxy, Kevlar, Styrofoam, and a transparent plastic film wing covering. The transparent plastic, allows the Helios to absorb solar energy not only from the sun, but also that which is reflected off the clouds below. The plane uses only 10 of the 36 watts produced by the solar cells. It was designed to reach a cruising speed of 19-25 miles per hour. It has 14 electric motors running on direct current, each putting out 1.5 kw, enough to run a common hair-dryer. Each motor runs a two-propeller system. Each propeller is about the length from the tip of your fingers to the shoulder opposite them. The craft can run as long as there is sunlight, and up to five hours on its storage batteries. Who could have come up with such a weird design and expected it to work?

Helios was imagined in the early 1970's by the United States Defense Agency. In the early 1980's this group designed and built an early prototype. The agency decided that the technology had not yet been developed that could make their dreams possible. In 1993, the Ballistic Missile Defense Organization began some testing, to determine its capabilities. Disappointed with what they found, the early prototype was turned over to NASA and its Environmental Research Aircraft and Sensor Technology (ERAST) in 1994. The ERAST team has been working on improving it in many ways. In October of 1994 there was a devastating hanger incident, which set the team back for almost a year and a half. Then, late in 1998 the prototype was modified to a longer winged craft. Since then, it has had various upgrades in electronics, energy storage, and energy collection. Helios is the only thing that travels in an atmospheric level of 19 miles above sea level. Radio waves spread out the longer they travel, so using the lower Helios instead of satellites, would require much less energy. The total cost of the plane is 15 million dollars, 10 million of which was spent on the solar panels.

NASA raves about the cost effectiveness of the Helios project. It costs only 5,000 dollars for every hour of flight, compared to 10,000 for every pound of equipment put into space. The Helios will be used for collecting atmospheric samples and surveillance. Scientists will use it to study growth patterns, migration patterns, to monitor storms and their development, and many other things.

The ERAST team has set two goals for the Helios: to fly on solar power up to 100,000 feet and; to fly for 96 hours in continuous flight. As of today, the plane has risen past an altitude of 96,000 feet. Its longest trip so far has been 14 hours of continuous flight. By 2003, the ERAST team will have produced and installed a new energy system which will allow it to remain in the air for nine months at a time. This energy storage system collects hydrogen and oxygen from the atmosphere, and stores them in separate tanks. When the sun is blocked by either clouds or the horizon, the battery will form water with the stored hydrogen and oxygen gas. The energy produced will be used to power the wing plane until it can depend on solar energy again.

On the plane during its flights are the Digital Array Scanned Interferometer (DASI) and the Airborne Real-Time Imaging System (ARTIS). The DASI uses less than 100 watts of power and weighs less than 18 pounds. The DASI and the ARTIS take different types of pictures. The DASI is limited by its size and its distance above ground. It is not mobile and therefore can only take pictures of areas directly below the body of the plane. The ARTIS is a connection of cameras that can be positioned anywhere on the plane. These cameras as well as other aircraft flying next to the Helios have recorded the plane in flight, during takeoffs and landings. During all flights previous to the last one in July of this year, there has been a helicopter traveling with it, as required by the FAA. The aircraft has been tested on a Hawaiian island because there is less air traffic, more open radio waves, and more direct sunlight than another available facility.

The ERAST team relies on a stationary control station in California, and another mobile van control center. The mobile control allows it to travel the world, which will be helpful during long flights where the plane will need to follow available sunlight. Because there is too little air above 75,000 feet, the crew must be especially careful not to let the parts overheat.

In flights, the payload is equally distributed over the body of the plane no matter where the bulk is placed. This is possible because the plane itself is flexible because of its compository makeup. There are six sections and five joint columns. At each of the five joints, there is about seven feet of power source equipment and landing gear. The landing gear consists of two relatively small wheels. The front wheel is the size of a scooter wheel, and the back is the size of a small mountain bike wheel. The aircraft has made a successful landing in water.

This light weight, sturdy plane capable of flights above 100,000 feet for over nine months, with a renewable energy source, seems to be capable of everything. Helios has been dubbed the Eternal Airplane. Whatever happens in the future, this is one NASA project you should be sure to watch.