Introduction: Aerobatic R/C Airplane
I wanted to scratch build a smaller R/C plane that could fit in my car completely assembled. I decided to make the wingspan 36 inches since this is the standard size of balsa materials. When I get to the flying site, I just plug in my battery pack and fly. I designed the plane to be super lightweight yet able to withstand the violent stress of aggressive 3D flight maneuvers. The plane is all one piece and there is no need to bolt on the wing every time I want to fly it. Because of the faceted shape of the canopy and flight surfaces I named the model "The Angler 3D"
The air frame is made of the following:
2 sheets 1/16 inch balsa
1 sheet 1/8 inch balsa
6 pieces of 1/4 inch x 1/4 inch x 36 inch long balsa sticks
6 pieces of 1/2 inch wide x 1/8 inch thick x 36 inch long balsa sticks
1 piece 1/8 inch x 1/8 inch basswood (12 inches long)
1 piece 2 inch x 2 inch plywood (1/8 inch thick - 5 ply)
Step 1: Layout of the Airfoil Shape for the Main Wing
I used a thick symmetrical airfoil for several reasons.
1. Allow for sustained inverted flight.
2. Keep the speed down in a dive, the thick airfoil adds a lot of drag.
3. Gives the wing more strength in wild/tumbling flight maneuvers
I traced the airfoil onto a stack of 1/16 inch balsa rectangles and cut all the ribs at once with a scroll saw.
Each rib is notched to receive the 1/4 inch balsa sticks that serve as the leading edge/spars.
The trailing edge is a 1/8 inch thick x 1/2 inch wide balsa stick (36 inches wide, the width of the wing)
The 2 flat extensions at the bottom of the airfoil are used as alignment jigs for building the wing on a flat table
(the tabs are cut off after the wing is glued up and removed from your building board)
Step 2: One Complete Wing Panel
The ribs are glued to the spar, this is repeated for the left wing panel.
I use a wood glue instead of CA because I tend to be messy when I use super glue type adhesives.
Notice the placement of the 1/4 inch main spars and 1/8 inch thick x 1/2 wide lower spar.
I used 1/16 inch balsa (with vertical grain) to add shear webs between the spars for strength.
These shear webs are a very important aspect of the wing structure and should not be omitted!
Step 3: Begin Building Fuselage Around the Wing Structure.
Step 4: The Build in Progress, What a Mess!!!!
Step 5: Adding Ailerons to the Wing.
I decided to go with built up ailerons to keep them light. You will need to build two that are identical.
I build one aileron, then lay wax paper over it and build the second one directly over the first one.
The ailerons are made out of 1/8 inch thick x 1/2 inch wide balsa sticks.
The ailerons are very flimsy but become very rigid after they are covered with the covering film.
The ailerons are extra wide to provide a very fast roll rate.
I hinged them with the matching color of covering film material.
Step 6: Layout the Tail (rudder and Elevator)
The tail is glued up flat on the building table.
I built the structure directly over my drawing (drawing was covered with wax paper first)
The tail structure is all 1/8 inch sheet balsa stock.
There is a 1/8 inch square basswood stick that is used to connect the individual elevator panels as one unit
Step 7: Added the Tail Assembly to the Fuselage Structure.
The tail surfaces are covered and glued to the rear of the fuselage structure.
They too are hinged with covering material for hinges.
It was easier to cover them before gluing the parts to the fuselage.
Step 8: Building the Front of the Fuselage.
This area was reinforced with 1/8 inch plywood.
The 370 size brushless motor fits neatly into this area.
I made sure and allowed for airflow to help cool the motor controller circuit board.
Step 9: The Covering Is Finished.
The wing was covered first, then the fuselage was covered.
The covering material is heat shrunk over the air frame and provides a drum tight finish.
It took one roll of covering to complete the model.
It takes a lot of patience to get this process right without any wrinkles or tears.
Step 10: Electronics - Servos - Motor
Step 11: The Electronics Are Installed in the Nose.
Step 12: The Servos Are Installed for the Control Surfaces.
This is the aileron servo with a carbon fiber pushrod.
There is one servo on each side of the wing.
The servos are underneath the wing panel.
Step 13: Added Black Trim to the Canopy.
The black film at the top of the model helps me to see the orientation of the model in flight.
Step 14: Top View
The fuselage is very skinny.
I designed it so that it had very little drag when doing some of the tighter maneuvers.
The model is now ready for flight.
It was balanced at the center of the wing spar and the center of gravity was perfect.
The plane flew great on its maiden flight and required only a small amount of up elevator trim to get it to fly level and hands off.
I am still learning how to fly it to its limit but am happy with the overall performance of my unique design.
This was a fun project and I really learned a lot.
Its hard to build a lightweight model, but the payoff is a model that flies better and climbs faster.
In my opinion, the best way to learn how to build a plane from scratch is to buy a name brand balsa kit, and build it following the manufactures plans/directions as directed.
This will prepare you to create you own design that will be unique to you. Good luck on your build.
Participated in the
Make It Fly Challenge