This airframe was designed to meet the ten below criteria with the final goal of carrying an aerial mapping payload.
Before designing the Black Eagle I sat down and drew up a list of design aspects that I would like to include in the plane:
The plane must be energy efficient and have the ability to operate for long durration photography missions
The plane must be easy to build using well know construction methods
The plane must be easy to repair and modify
The plane must be easy to balance (easy to find good CG)
The plane must be cheap yet sturdy
The plane must be ready to accept FPV and APM systems
The plane must be able to carry a high-definition camera
The plane must be easy to fly and fly well in "iffy" conditions
The plane must have the ability to operate in suburban environments
For testing I used a 2200Kv motor with a 6x4 and some small servos. The ESC was a Hobby King 40A. The final version will most likely have a 1100Kv and a much larger prop.
I used cheap packing tape and red and white Elmer's foam board.
This is an unproven design and this Instructable is just a general explanation of the build process. Please adapt this design to meet your mission. If you do, I would appreciate if you left some pictures in the comments.
A little note on the name: The name Eagle was chosen because this is an aerial mapping UAV and some eagles can spot prey when they are 4500 feet away. I thought that it was appropriate for two birds with good eyesight to share a name. It is the Black Eagle because I plan to build a carbon fiber version.
Step 1: Design
The first step I took in desgning the B.E. was making a CAD model. I then tweaked the model based on some physics calculations, the main one being cg. The airframe is desgined to, at its maxiumum carrying capacity, hold FPV and HD video gear all the way in the nose and the autopilot, mapping camera and battery right under the wing. It surprised me that even with this setup the plane was a bit tail heavy, an issue easily resolved by moving the FPV battery and tx a couple inches towards the nose.
A couple notes on my design choices:
The main reason I choose the twin boom fuselage style was because it minimizes unnecessary fuselage tubing. In this I mean that there is no drag inducing large tube between the tail and wing. This not only makes the plane eaiser to build and repair but also allows for a reduced side surface area which should increase preformance during high wind missions.
In the CAD model the plane has a V tail. My prototype with not have this type of tail but it is an option for future versions. My first version of the B.E. won't even have a rudder, just an elevator.
The model has a 5 inch chord and 1 inch control surfaces. I will be first testing this model with a 5 inch cord wing from another project of mine. To ensure that the drone can fly with a high level of stability while at a low power setting, my payload carrying version will have a 6 or even a 7 inch cord wing.
Please take a minute to look through this step's pictures, the annotations explain each design aspect and its utility.
The C.A.D. model is attached.