Background: On August 13, 2001, the solar-powered Helios Prototype flying wing set a new world record altitude of 96,500 feet over the Pacific Ocean, fulfilling the expectations of engineers working at the NASA Dryden Flight Research Center. The remotely-piloted wing took off from the U.S. Navy's Pacific Missile Range Facility on the Hawaiian island of Kauai at 8:48 a.m. Hawaii Standard Time (HST). Flying at about 25 miles an hour, the mission lasted nearly 17 hours, landing at 1:43 a.m. August 14, 2001.

This is the first time a non-rocket powered aircraft has maintained flight this far above the earth. Sustained operations at that altitude promise to enable capabilities ranging from environmental monitoring to radically improved communications on earth to simulating flight in the atmosphere of Mars, since the atmosphere at that height above earth replicates the atmosphere near the Martian surface.

The Helios Prototype is a remotely piloted flying wing aircraft that is part of NASA's Environmental Research Aircraft and Sensor Technology (ERAST) project. Developed by AeroVironment, Inc., of Monrovia, CA, the Helios Prototype is a lightweight all-wing aircraft with a 247 foot wingspan. The Helios Prototype was developed from the Centurion aircraft by adding 41 feet to the wing span, an additional landing gear and systems support pod, and other technical upgrades. Remarkably, its wing span is longer than the wingspans of the Air Force C-5 military transport (222 ft) or the Boeing 747 commercial jetliner (195 ft), the two largest operational aircraft in the United States.

Click here for a photo of Helios' wingspan relative to that of the Centurion and other predecessor aircraft.

The all-wing aircraft is assembled in 6 sections, each 41 feet long. An underwing pod is attached at each panel joint to carry the landing gear, the battery power system, flight control computers, and data instrumentation. The Helios Prototype shares the same eight-foot wing chord (distance from leading to trailing edge) as its Pathfinder and Centurion predecessors. Thus, the 247-ft wingspan gives the Helios Prototype an aspect ratio of almost 31 to 1.

What is the "aspect ratio"? Simply put, the aspect ratio is the relation between an object's length and height. In the case of the Helios Prototype, the length of its wingspan is 247 feet. Its height, or what the Dryden scientists refer to as "wing chord" (which is the distance from leading to trailing edge) is eight feet. Thus, the wingspan (length) is approximately 31 times longer than the wing chord (height). Here is a real-life application of ratio!!

One can also talk about aspect ratio in computer graphics. Given a graphic on the Internet, if the relative horizontal and vertical sizes. For example, if a graphic has an aspect ratio of 2:1, it means that the width is twice as large as the height. When resizing graphics, it is important to maintain the aspect ratio to avoid stretching the graphic out of proportion.

Learn some facts about the Helios Prototype.
View photos of the Helios Prototype.
View movie clips of the Helios Prototype.

The Activity:

Even more challenging might be to have students to find an object that is 31 times shorter than they are. Thus, if a student measures 4 feet tall (or 48 inches) they need to find an object that measures ~1.56 inches tall!!! This could be a challenge for students and might produce some creative examples! For example, a student who measures 48 inches is ~31 times taller than a nine-volt battery or ~31 times taller than a package of tic-tac breath mints! This means that a student would have to stack 31 nine-volt batteries (or tic-tacs) , one on top of the other, to match their height!

It is hoped that by having students compare their height with an object that is 31 times their height (or, 31 times shorter), they will come to a better understanding of how long the wingspan of the Helios Prototype actually is (relative to its height) while learning about ratios at the same time.

Enrichment Activities: