The goal of this project is to design and build a working, 3D printed ornithopter. To highlight the advantages of 3D printing, our team is trying to reduce the number of individual parts in the final assembly by combining complex geometry into a single part that is only possible with additive manufacturinig.
The initial design was taken from Thingiverse (http://www.thingiverse.com/thing:239789). The design, which is displayed in Figure 1, is evaluated in accordance to the Material Extrusion design guidelines.
Figure 1: STL file from Thingiverse
The part in the upper left corner is the backbone, and the other two parts are the wings. With the original design, the wings are printed separately, which requires one wing to be glued to the backbone during assembly, which is unnecessary. Additionally, the original backbone has many cutout sections, which would require a large amount of support structure during the print.
By redesigning, the complexity of the attachment mechanism was reduced. The design of the wing was not altered significantly, as can be seen in Figure 2. However the angle of the slot had to be changed so that the drive mechanism would be able to successfully flap the wing – this was done by mating parts in an assembly with a drive arm to check that it could rotate freely while flapping the wing.
Figure 2: Wing
The wing and the backbone parts were combined, as seen in Figure 3. The adaptations we implemented allow for better printability and reduced the number of assembly steps.
Figure 3: Combined wing and backbone
These designs detail the first stage of parts that will be printed and tested. Based off of these preliminary designs there will be modifications to improve flight performance and enhance the design aesthetics. The group’s goal is to take the basic ornithopter design and modify it so that it resembles a bat. Figures 4 and 5 show some design concepts that we are considering for new wing shapes. The cut-out design allows for a lighter device, which will be necessary for successful flight. In this design, the cut-out area would be covered with a light and flexible material. This design will go through a number of iterations to improve its functionality and printability.
Figure 4: Full wing
Figure 5: Combined full wing and backbone
Initial tests of the first design are promising, though it needs to be strengthened to allow it to support the rubber band without breaking: