How many ways can you make a hovercraft? Particularly one that runs on batteries! Recently I had the good fortune of helping at a science completion for students, and the ideas and cleverness from the young contestants was far more diverse than anyone could have predicted. The Tech Challenge, held at The Tech Museum of Innovation in San Jose, California, was very well run and had support from several corporate sponsors. The overall presentation of the event was also major league, but what impressed me the most was that, even though it might seem that there would be only so many ways to make a home built hovercraft for the competition, the grade school through high school student teams had endless variations on their designs.
Most were simple low cost solutions that the students came up with themselves. As a judge, we looked closely while interviewing the students about their design, to confirm if they did the work themselves, and using a kit was a negative in judging. And although the competition had a recommend project approach outlined for each student team, which they were to follow and report on in their design journals, the outline was basically recommendations on good design processes, ideation, discussing ideas and testing them. This allowed the young competitors to develop their concepts more efficiently, and learn, not just how to problem solve, but to work together.
And the results of the students’ efforts were very diverse creations. Sometimes a concept didn’t work, sometimes a late change in the design just before the competition was a setback, but many times the cleaver use of simple materials and open young minds had great results. Even the setbacks offered learning opportunities, and these things were discussed. There were unintended consequences, like having two electric motors rotating in the same direction, causing a light weight hovercraft to always drift to one side of the test track, and even if the benefit of making one motor rotate the other direction was not understood, I saw one very successful team of girls who had added light weight out rigger spars to help direct their tiny vessel along the track’s curb to make it to the finish line. The innovation and adaption was successful, and, let’s keep in mind, they were middle school students, and most likely had not yet been exposed to the gyroscopic concept of procession.
The competition was successful in getting students to test out different concepts before the event. Although it was anticipated that most designs would have at least a lift motor with a propeller, and a separate propulsion motor and propeller set up, one group of young contestants figured out they could save weight and still move forward by just having two lift inducing propellers mounted at 15 degrees (angled back) as this moved the craft forward enough on the test track to completed the course in time. With their lower overall weight and extra under craft airflow they could successfully cross the dread last leg of the course over a series of holes in the track surface. This was a very serious challenge for some. No manual forward propulsion or benefit of gravity (tilted track) was permitted at this stage of the competition. Other teams approached this with designs that tried to moving forward very quickly to shoot over this region in the track, but losing all that lift on the perforated track could cause too much drag, and get a hovercraft stuck. Some teams tried to extend their hovercraft’s foot print enough to keep some of the lifting air skirt always outside the hole pattern, with varied results.
The power input was limited, and even if not fully analyzed and engineered by the teams, the trade offs of motor size for lift, and motor and battery weight were understood well by the competitors, with most trying to be as light weight as possible. As I understand it, until the appearance of jet aircraft in the ‘40’s, this same challenge, power density of the engine, or horsepower per pound, and fuel weight, drove high performance aircraft designs for the first decades of flight, so it is an age old challenge. Teams showed up with Styrofoam plates for their main structures and take out lids. All excellent and clever choices as these have already been optimized for light weight and structure, although the food industry is shooting for low cost and some structure, and low cost was not lost on the student teams either.
Oddly, I had thought I might see some carbon fiber pieces or 3D printed structures for the hovercrafts, but refreshingly these really were not present. I say refreshingly, since I work in product design these materials and process are often talked about or utilized, and seen as a silver bullet for solving many issues, but the student team’s were resourceful, using what was available to them, working on their own, with materials that met the need for structure and low weight without having to re-invent their own structures from more costly materials. Few students have a 3D printer at their disposal, at least before high school, even in Silicon Valley, and taking parts from store bought kits was really not in the spirit of the competitions. So it was refreshing to see what the students drew on to build their crafts and meet the challenge without just cuing up 3D prints, optimized computational fluids analysis designs.
The challenge of building an inexpensive, light weight, fairly robust hover craft is actually complex, and for the time available the students were better served to build with simple, quick materials so that they could experiment with their prototypes right away, and vary their designs versus trying to optimize virtual designs or digital twins, delaying their fielding testing and slowing their flexibility to try something else. The rapid build and test approach allowed for the teams to learn more, quickly, and makes for a good reminder for us that innovative design, and design success, doesn’t require long, expensive development cycles, but maybe benefits more from initial free thinking, cooperation and lots of hands on testing of ideas.
Many of these students will go on to a formal education and may design things that change our lives. They will go through a more formal process in these future designs, leveraging of a deeper understanding of the physics behind the development, but their creativeness, curiosity and maybe new found experiences of meeting a design challenge will serve them well as they innovate the world in new directions.