Assembly and installation of the main landing gear in the DarkAero 1 prototype was a primary goal in October. The remaining machined and molded components of the main landing gear structures were completed, and the first session of the DarkAero Aerospace Composites Course was conducted this past month.

Main Gear Trunnion Frame Assembly
The main landing gear of the DarkAero 1 is tied to the airframe through a carbon fiber structure called the trunnion frame assembly. The inner trunnion frame is made up of two halves, left and right, which are formed on a mold through vacuum infusion. The design of these parts may change based on testing, so we chose not to commit them to a production mold just yet. Instead, we built a prototype mold from MDF to proceed quickly with a cost-effective, readily available material. We designed a mold that would allow us to create both of the inner trunnion frame halves in a single infusion. It had very different geometry compared to other molds we have constructed in the past, so it was a good project to broaden the range of mold designs we have tackled. Ultimately, the prototype mold worked as planned, and we were able to achieve a successful infusion of the inner trunnion frame halves. 

Once the left and right inner trunnion frames were infused, we were able to demold, trim, and test fit them into the full trunnion frame assembly. The full structure not only provides an interface for the main gear to attach to the fuselage, but also forms the walls of the recesses that each main gear strut retracts into.

When we initially CNC cut the fuselage bulkheads, we left the bulkheads around the main gear area solid, with no cutouts for the gear struts or other hardware. At that time, we knew we would be iterating on the gear design for a bit longer, so we decided we would just create the cutouts by hand later when the main gear revisions were complete. The cutout sizes and positions have since been established, and we proceeded into updating the bulkheads with the necessary cutouts to receive the trunnion frame and main gear struts.

Main Landing Gear Trunnions
In the September update, we discussed the challenges we faced while manufacturing the composite trunnions located on top of each main gear strut. We worked around these challenges by moving to a different version of the trunnion design that is CNC machined from a billet of aluminum.

The aluminum version is still somewhat challenging to make on our Tormach 3-axis mill due to the geometry and size of the part. ​​The main difficulty centered around creating the bore in the trunnion that serves as the pivot point for the gear strut. The bore is long relative to the size of our standard cutting tools, so we purchased some special tooling to create this feature, and ran a series of tests to dial in the correct machining feeds and speeds that would yield accurate dimensions and a smooth surface finish. After working through the test cuts, we were able to move into the final machining operations to complete the trunnions. These components would be more straightforward to create on a larger CNC machine, but all of the challenges gave us a clearer picture of what machines we will need to effectively produce these parts in production.

The completed trunnions were trial assembled to the composite gear struts to confirm their fit-up and validate our planned assembly procedure. It was pleasing to physically see and hold the full gear strut assembly with the trailing link, wheel, and shock after looking at the design in the virtual 3D CAD environment for so long.

DarkAero Aerospace Composites Course
The first session of the DarkAero Aerospace Composites Course was held this past month, and it was a success! Those who attended went through two days of instruction ranging from technical theory to hands-on demonstrations centered on building a small wing section. The material covered in the course shares aspects with the training and instruction we must develop to train a skilled workforce to build DarkAero 1 kits when we enter production. We are already booked up for our second session on November 5-6 and are planning on holding more sessions this spring. If you are interested in joining a spring session, contact us at info@darkaero.com to register.

YouTube
We released a new YouTube video documenting the creation of one of the structural components in the landing gear assembly, the trunnion frame. That video can be viewed here: 

Most Complicated Carbon Fiber Part in the DarkAero 1!

In addition to the public video we released on the trunnion frame, we published a video to our YouTube Mach 2 Community Members that captured a discussion of the main gear trunnion design evolution and an overview of the inner trunnion frame manufacturing:

Manufacturing the Inner Trunnion Frames

Looking Ahead
In November we will continue integrating the trunnion frame into the fuselage and complete the assembly of each main gear strut. Manufacturing and assembly of the hardware in the main gear retract mechanism will be a new area of focus and we will be conducting the second session of the DarkAero Aerospace Composites Course.