2017 Science fair project. Scratch building out of foam a scale 747 with electric ducted fan engines
What do you do when your 14 year old son comes out of a store with 32 sheets of foam board and wants to build a remote control 747? Interesting question! You go with it!
We had been into model aircraft for a while, but had never built a plane from scratch. I thought that he wanted to build a plane similar to the flight test foam planes that he had previously built. That was way off from want he wanted to build! As we started to layout the plane on the ping pong table, I soon realized what he wanted to build was much bigger and a giant scale plane. He said he wanted to build a scale 747 that was 9-10 foot long with 4 electric ducted fans. I knew it would be a huge project that was probably beyond our skill level, but I went with his idea.
At the same time we began the building process, my son needed an idea for an 8th grade science fair project. We mentioned his model plane project to his teacher and showed him a few early pictures. The teacher recommended that he should use it as his science fair engineering project. Great, we killed two birds with one stone! We had three months until it was due.
Knowing that time would be an issue, we got busy building and trouble shooting the many problems we encountered. The goal for the science fair was to mainly use foam board and hot glue to build a plane that could taxi, takeoff, controllably fly for at least 15 seconds, and land without a structural failure.
Once we had the rolling, partially covered fuselage and the wings in place, we noticed that we had significant wing droop and flex in the fuselage. We needed more strength so we doubled the foam ribs, added foam stringers, added balsa supports, and a few carbon fiber rods in each wing.
At this point, we began to wonder where we could flight test the plane. A nearby hobby shop referred us to a local RC flying club, RRCC (Richardson Radio Control Club) who had their own paved airpark. I contacted the president and was invited out to a fun fly event. This was the lifeline we needed to finish the project!
The wealth of knowledge that we had tapped into was invaluable. We met a RRCC member, Brad. He offered to advise us on the project and help test the engines. As it turned out, he helped us to finish the build. I am pretty sure we wouldn’t have finished the project on time without his expertise! I will just say the last three weeks before the project was due included many late nights and full build days.
In the end, the airplane weighed 41 pounds with approximately 45 pounds of thrust. We installed four 90mm EFD and ran 2 - 4s batteries in series (8s) and 22,000 mah. To ensure we had the best possibility for a successful flight, we asked Brad, with his years of experience, to fly the first flight.
We finished the airplane late on the Saturday night before the project was due, which left us one day for the test flight. The weather that day was perfect for RC flying. The airplane taxied and lifted off in 136 feet. The climb performance and handling was great and Brad said it flew really nice. Midway through the flight we lost power on all the engines. This was due to a de-soldering of a Battery series connector that we had purchased. Luckily, Brad was able to turn toward the runway and glide it down for safe landing. We were using a separate receiver battery pack for the flight controls!!
Building this airplane was a huge learning process for me and my son. It included many hours of father son time with a common goal-priceless! For the weeks following, my son and I would say to each other “IT FLEW!” As for the science fair grade and competition, he is still waiting to hear back.
Vice PresidentLawrence Harville