Stein said the plane will reach 13 mph when it soars along a zipline strung from a backyard tree to the contraption. The fact that the glider has truncated wings does not disturb him. There's no room in the driveway for a 32-foot wingspan, he said.
Large plastic barrels stop the aircraft. But nothing will stop Stein, 86, from manning the plane for a test flight along the zip line. First, though, he must perfect the shock absorbers and other modifications his daughter, Sandy, is requiring before he takes off, he said.
Stein, a retired Silicon Valley aeronautics engineer, has found a way to share his knowledge and enthusiasm for flight. Since January 2011, he has taught 15-week aeronautical engineering classes in his Duveneck/St. Francis neighborhood garage to middle- and high school-age students, whom he refers to as a "squadron." Each week the students apply math and physics to hands-on projects.
During the school year, Introduction to Aeronautical Engineering class members have made and tested small-scale aircraft and built their own wind tunnels.
Stein said the instruction isn't like that found through model-plane clubs.
"There have been a lot of classes where kids build model airplanes and fly them, but none on the engineering behind designing the aircraft," he said.
When the space shuttle made its farewell tour over the Bay Area, Stein and the students discussed its design and why it worked. They also looked at modifications to the 747 on which it piggybacked, which made it possible to transport a shuttle that weighed almost the same, he said. The students learned about aerodynamic drag.
"They had to add extra fins on the 747 to interact with the turbulence," he said of engineers.
In summer 2011, students built a primary glider and the Langley glider. They learned not only how and why something flies but, in the case of the Langley, why it failed.
"It has wings in the front and back but no control system. The pilot has to shift his weight to control it," Stein said.
Although work on the glider is not now part of the regular class, the plane is still being modified through Stein's 511th Aero Engineers Squadron Club. Students enrolled in classes automatically qualify to be members. The club meets outside of regular class and includes model building and flying, field trips and other activities.
Besides listening to lectures and performing calculations, students in all classes work on a three-dimensional project and learn how to create engineering drawings.
This fall they designed hand-built wind tunnels. A model plane was attached to a moveable platform and connected to digital load cells, which collect wind-tunnel data. The students use the data to solve equations, such as air velocity, height and drag, as a fan blows air across the plane and gently lifts the platform.
They'll have a competition to build their own airfoil shapes and tunnel-test them, he said.
"It will be competitive, and that really gets exciting," he said, smiling.
As a boy growing up in Los Angeles, Stein recalled that he was surrounded by influences of the pioneering days of flight. Charles Lindbergh became the hero of the trans-Atlantic flight one year after Stein was born in 1927, and barnstormers were touring all over the U.S. showing off the marvels of airplanes.
Stein worked for Ryan Aeronautical Company in San Diego, Lockheed Corporation (now Lockheed Martin) and McDonnell Douglas Corp., Bechtel Corporation and Hiller Helicopter.
A helicopter he helped design hangs in the Hiller Aviation Museum in San Carlos.
The students perform pretty much the same tests he performed, only scaled down, he said.
"It's very safe," he added.
Students are organized into research teams, and each has a turn to be director, platform manager, load-cell manager, data taker and quality program manager. They have squadron titles such as "lieutenant" and "captain."
Stein said so far one child out of about 14 was definite about a career in aeronautical engineering. But that's not his main goal. He hopes to awaken the potential in each child, he said.
"It really is something I think about when I see somebody 10 to 12 years old and they do something at the graduate school level," he said.
Stein has been surprised and delighted by the students' ingenuity, he said. One 9-year-old girl, Ana, a fourth-grader at Duveneck Elementary School, even invented a retractor that pivots the propeller so it doesn't block the driveway when the Langley isn't being tested.
Ana's accomplishments were transferred onto a model she built and flew. She and the other students held a flight contest at Rinconada Park with planes they built.
He recalled her reaction after the contest — a response that would warm any teacher's heart.
"We gave her an extra propeller blade as a recognition of her accomplishment. She held that thing like it was her favorite doll," he said.
Stein's winter classes in January 2013 will involve building a model airplane and designing a propeller.
Students can view a video of Stein and the building of the glider at www.aeroengineeringeducation.com. Stein's daughter, Sandy, has a master's degree in communications and is helping him develop a video version of the classes, which will soon be available.