@superhappyfun you ever get a mini sea duck in the air? Curious how it went...
Yes! I did eventually get around to making this. It took a while though. I downloaded the PDF plans and using Adobe Acrobat Reader cropped each section of the plane I wanted to build and shrunk the plans down to 72% and cut the foam using a box cutter, which resulted in a 1054mm wingspan. I'm not very good at scratch building so my cuts were kind of jagged in some cases and I had to cut the hole in the fuselage that the main wing passes through a little wider because scaling the plans down did produce some "fitting issues". I think this was because I used 5mm foam from the Dollar Store, which is a bit thick in my opinion and when you scale down plans but keep the foam the same thickness it can cause these issues. I also reinforced the wings with a balsa wood rod and filled in some of the gaps with Great Stuff expanding foam to keep water from getting in. I reinforced the bottom of the plane with some 1/64 mm plywood I picked up at an arts and craft store and I sealed the seams of the plane with coffee filters and glue (kinda like using paper mache). For electronics I used Emax 4.3 gram servos (ES9051), two EMAX 1806 2280kv motors on 6030 props powered by two Arris Blheli 20amp ESCs. With these props on max throttle I pulled about 12amps per ESC, or 24 amps total. I powered this using a Lumenier 1300 mAh 3S battery, which gave me about 5 minutes of flight time. I used a lemonrx receiver and set my controls up to use flaperons. There is no particular reason why I chose this electronic setup though, I just happened to have these parts lying around, that's all.
For me it flies well, but my opinion on what a good flier is might be different from everyone else. I didn't want this to be a pylon racer or a 3D plane and it's not. The purpose was to recreate a smaller version that I could land on the pond in my neighborhood with docile flight characteristics. My worries were that this wouldn't fly at all because I did a lot of glueing and reinforcing, AND I used thicker foam. In the end, this bird was heavy, the full build weight with all electronics and no battery is 560 grams, which is probably 100 grams over where it should be, but in spite of that the power setup got it into the air just fine. It was a bit of "clumsy flier" though, but this setup gives it plenty of power and a straight up vertical was achievable because at max throttle each engine puts out about 450-480 grams of thrust or 900-960 grams total.
The remaining tasks are to paint it. I'll probably coat with some water based polyurethane on the main fuselage and a final coat of paint using the classic Sea Duck paint scheme. I might skip the motor cowls too, but I'm really not sure. If I get a chance I'll try to post a flight video, but I don't have a great camera setup for this so I don't count on that happening anytime soon, maybe I can coax my wife into coming out to the flying field and getting some footage using a phone camera.
If I had to do it again I would have tried to find thinner foam, probably 3mm would have been better and I might have been more conservative with the glue and not used the coffee filter approach, not that the coffee filters added that much weight, but I think it was a waste of time for something that could have been achieved more easily simply by using hot glue.
Attached are some pics from various parts of the build process. Hope this helps!
