In my collection of 100+ vintage kits sits a Sorrell HiperBipe from Master Kits by Frank Massa. Without disturbing the original kit, I carefully copied the plans and traced every part. I worked out the weight and ordered an AXI power system to give the airframe plenty of power. Framing the fuse went quick but that’s as far as I got, it has been sitting in my hanger for 5 years.
My love for the HiperBipe goes back to about 1978 when my dad purchased a Master Kit. He colleted photos and articles but never got around to building it. I just purchased a CNC router and was looking for a project. After designing some of the small 3D plate foamies, I wanted to try a larger hi-bread using Depron and wood. A full fuselage was a must and an airfoil style wing would be really nice. AXI just came out with the 2826-10, using this and 3-4S li-poly batteries makes a great low KV motor with a lot of torque and can swing a large 13” prop. The target weight will be between 3 and 3.5 lbs, with 450 watts the HiperBipe should hover!
Using my old copy of the HiperBipe plans (the original design had a 42” wingspan) and a 3-view that my father had in his collection, a 48” monster emerged. Using CorelDraw to produce the drawings and plotting them full scale. The final CAD files were imported into CNC software to produce the G-code. The router ran for 3 days sometimes cutting parts 2 or 3 times to get things to fit, remember this was my first project with the router and also my first hybrid foamie. Once the lite-ply and foam fuselage parts were cut, construction went quick; I had a lot of fun assembling and watching this huge bi-plane come together.
After producing a couple test samples, the wing design came together. The final design was a 12mm thick Depron composite using 3 layers and a carbon spar was embedded in the middle core. The 12mm tapered core gave me room for servos and ending up with 6mm at the trailing edge. There is four wing panels that are made to be removable for transportation. The flying wires need to be removable also, this ended up being a major design task. I have also made the wing joiners adjustable; the decalage on a reverse stagger can be a challenge. I started with zero degrees on everything and never did any further adjustments.
Next, was to carve a wood plug for the cowl and windshield made from layers of MDF particle board, the wheel pants were carved from balsa. My vacuum former is large enough to pull all of the styrene parts in one pull and used clear Lexan for the windshield. This plane has a huge cowl and windshield; these were a major part of the airframe, now the plane was taking some shape. The only thing left was to design and cut the vinyl numbers and markings; I decided to go with the original Sorrell design keeping the airframe clean and simple using the white Depron with teal trim. I went back to the CorelDraw CAD files to layout the trim and numbers. I cut the vinyl on my 24” cutter and had the trim finished in a couple hours.
These are the specifications for this build.
HiperBipe 1/5 Scale –
- 48” wingspan, 768sq. in., 9.5 oz/ft loading
- AUW 48 oz’s
- AXI 2826/10
- APC 14x7E
- 3S2P 3140 mah Li-Poly