Although author Rick Michelana likes the looks of a giant-scale biplane, he didn’t want to have to spend almost
an hour setting it up at the field. His sport biplane is built-up with foam wings and covered in fiberglass, and
it uses landing gear, wheel pants, and a cowl from an ARF model. See how Rick’s giant-scale sport bipe came to life in this online how-to:
One weekend, I watched two modelers assembling their giant scale ARF biplanes at our flying field. While the look of a biplane is great, I was not impressed by the fact that it took these men almost 45 minutes to assemble their models for flight. I thought that I might like a sport biplane without all the assembly time. Therefore, I planned to scratch build one around the following parameters:
* It had to assemble very quickly; therefore, I would not use cabanes or N-struts.
* It would be built with balsa, plywood, and foam wings.
* I would design the fuselage around a pre-existing ARF cowl.
* I would use available ARF landing gear and wheel pants.
* It would be covered in fiberglass cloth and auto paint.
The following photos will document how this giant scale sport biplane came into being. All captions are below the pictures:
A friend and I cut four sets of foam wing cores. I cut “washout” into these fully symmetrical foam cores. These will later be sheeted with 3/32″ balsa skins that I will make.
Once the wing skins have been glued on, I will attach balsa leading and trailing edges cut from balsa sheets.
I used 1/4″ balsa in the rear and 3/8″ balsa in the front. I glued these on with Elmer’s carpenter glue and taped them in place until it dried.
I will use a razor plane and a sanding block to create the leading edge profile.
Excuse the fuzzy picture, but you can still see the finished shape verses what I began with.
I laid out the sides of the fuselage using 1/8″ balsa. I reinforced the firewall area, tank compartment, and wing attachment points with 1/8″ Mahogany door skins purchased at a local building supply. I made two identical pieces and used a hole saw to lighten them up.
Both sides were glued with carpenters glue and weighted until the glue dried.
I made a front and rear bulkhead from 1/8″ door skins. I will use the blue line on my table to ensure a straight fuselage.
I cut 1/8″ balsa strips and glued them with CA to the inside of the rear fuselage for added strength.
I added balsa gussets and sticks to complete the rear of the fuselage.
Before adding the firewall and sheeting the top of the fuselage, I drilled the wing dowel holes for both the top and bottom wings. I will employ two 1/4″ X 20 steel bolts to attach the wings to the fuselage. This technique allows this model to assemble in under five minutes. This was my first design parameter.
With the wings attached, I sheeted the top of the fuselage and made a fire wall that would fit a Great Planes Cap 232 cowling. My second and third goals are now established.
I’m using a US 41 that was lying around the shop. Since I will employ a 4″ spinner, I am making a new front ring from plywood, balsa, and some filler.
The engine is bolted on. As you can see, everything fits well.
I decided to cut some 1/4″ thick foam sheets. I will clue 1/16″balsa sheet to both sides. This will create flight surfaces that are 3/8″ thick and much lighter than 3/8″ solid balsa. It is best to always build light.
The model is now framed up. As you can see, I used two bolts per wing and no cabanes or “N” struts. This model goes together quickly at the field.
This giant scale airframe now weighs 7.5 lbs. The final weigh will consist of landing gear, wheel pants, fiberglass finish, engine with a smoke system, and radio equipment.
I painted the model white with orange and black trim. I went to my good friend at Sal’s Vinyl Graffix, and he made matching lettering.
I sanded the original paint off the Great Planes fiberglass Cap 232 cowling and painted it to match the airplane.
This is the finished product.
I used landing gear and wheel pants from Great Planes.
Another photo before heading out to the field.
We had a cloudy day. However, the smoke system is still visible. She flies as if it were a pattern ship, and knife edge flight is great in both directions. It is not difficult to scratch build. The results are a model that no one else has.