In October we continued working through builder assembly tasks on the wing and fuselage. The bulk of our wing assembly tasks were completed including the construction of the wing tips and full close-out and installation of the ailerons. On the fuselage, we completed installation of both the top and bottom cowlings and bonded in mount points for our engine mount. Outside of assembly work, we started on the construction of a copy for our canopy mold, had a wind tunnel model of the DarkAero 1 made, and spoke with the EAA chapter of Viroqua about our journey building the DarkAero 1. 

Tip Construction and Installation 
After exploring a new manufacturing process to create the horizontal stabilizer tips in September, we tested the same method on more parts in October. The new process is well suited for non-structural components and is faster than the infusion process we use for structural skins. We were pleased with how well the new process scaled to much larger parts like the wing tips, and we were ultimately able to successfully manufacture all the tip components. The tips for the ailerons, elevators, horizontal stabilizer, and vertical stabilizer are now fully bonded in, closing these parts out. We will complete final installation on the wing tips once we have our wing tip lights available.  

Forward Baggage Top
The forward top fuselage skin was bonded to the fuselage. This skin closes out the electrical components channel and the forward baggage compartments. In addition to the allowable storage behind the seats, we have also designed in two forward baggage compartments which we haven't talked about much. These forward baggage compartments provide greater flexibility for weight and balance options depending on the mission. The instrument panel is attached to the canopy and comes up as the canopy opens which provides access to these forward compartments. With the forward fuselage skin attached we were able to proceed with finalizing work on adding the fasteners for the upper cowling.

Firewall Forward Work
The top and bottom cowling halves are now both fully installed and mated to the fuselage. We used piano hinges as fasteners to join the cowling to the fuselage. We have had some questions about the ease of maintenance using these fasteners and at this point we can confirm that both installing and removing the cowling is a quick and easy task. Additionally, we installed structural hard points in the engine firewall. Our firewall is constructed out of a carbon fiber and aluminum honeycomb core sandwich panel. As a result, we needed to add carbon hard points to interface with the engine mount hardware.

Canopy Mold Copy
As discussed in previous updates, we are working towards rebuilding our canopy mold to help eliminate defects in our thermoforming process. The process involves first building a female copy, which we'll use to build our final male mold. This mold is particularly tricky because it has to be built in two halves in order to demold properly. Both halves are now built and will be demolded and prepped to construct the male mold in November.

Wind Tunnel Model
We worked with Midwest Prototyping to produce a 3D printed, 1/12 scale model of the DarkAero 1 for use in wind tunnel testing. A 3D Systems SLA ProJet 7000 printer was used to produce the model. This type of printer uses a laser image projected into a bath of photo reactive resin to print models in thin layers. The end result was a precision representation of the DarkAero 1. We also had parts printed to simulate different flap and rudder deflection configurations. To provide a stiff mounting point for this model, we machined a pylon out of solid carbon as well. The wind tunnel testing we intend to perform on the model will help us to further build upon the CFD or virtual wind tunnel testing we have already completed.

3D Printed Parts
We have been working with the University of Wisconsin-Madison's Polymer Engineering Center to experiment with 3D printed and carbon fiber laminated parts on the DarkAero 1. These parts are first printed using Digital Light Synthesis (DLS) on a printer made by Carbon, Inc. The material is a dual curing epoxy which is only partially cured during the printing process. After parts are printed, they are removed from the build plate, integrated with carbon fiber reinforcement plies, and then finished in a thermal curing process to co-cure to make a final part. This process is exciting because it eliminates having to waste material that would be removed through a subtractive process via machining a billet of solid carbon. We are currently experimenting, testing, and evaluating this as a potential manufacturing approach for full scale production. We have already tested out the process on several small components used for the control system. Further evaluation is required to determine if we will use this process rather than our standard billet machined carbon parts in production.

Control System Components
Initial construction has begun on the control system components for the DarkAero 1 prototype. The control system is made of standard aircraft hardware and is quite similar to what is found in many other homebuilt aircraft. So far we have fabricated the aileron torque tubes as well as the aft pushrods for elevator actuation.

Viroqua Talk
We were invited by the EAA Chapter 1439 of Viroqua, WI to speak about DarkAero and share our progress to date on the DarkAero 1. We had a lot of fun meeting fellow airplane enthusiasts and talking with them about the mission of our company and aircraft. We'd like to thank Marty for inviting us to speak, and we hope to come back to do another talk in the future. The full talk has been uploaded to YouTube and the link to this can be found below.

Looking Forward
Going into November we will be aiming to complete the control system for the aircraft. We will be constructing the male copy of our canopy mold, and if all goes well with testing we will be forming our production canopies shortly following this. We will also be machining our landing gear components as well as the engine mount.