Progress on the DarkAero 1 prototype continued in April with significant effort dedicated to the nose landing gear and instrument panel. We also brought a new intern onto the team and made a quick visit to Sun ‘n Fun.

Nose Gear Update
We continued our work on the nose landing gear update by manufacturing components for the design we began developing in March. The new design utilizes a gear drive mechanism rather than a linear actuator to retract the gear leg. This change was made to resolve the issues we uncovered using our simple gear retract test stand. We were able to finalize the new design and begin manufacturing it.

The first parts we made were the lower drag links. The lower drag links work together with the upper drag link to constrain the nose gear in the down locked position by preventing the strut from pivoting about its retraction axis. These simple, two operation parts were machined from 7075-T6 aluminum. 

The nose gear is connected to the airframe partially through the engine mount. The design update resulted in some changes that affected the engine mount so we continued our manufacturing work by machining new engine mount components. The backbone of the engine mount is formed by two rectangular extruded aluminum tubes. The UL Power engine and the nose gear both attach to these tubes. The first parts for the new engine mount were CNC machined to final geometry on our mill, but in production we are planning to have these parts laser cut on a CNC tube cutter. CNC laser tube cutting is an extremely fast and efficient manufacturing process so we are excited that we have a design that can take advantage of this process. 

By the end of the month we progressed to machining the new nose gear trunnion halves. The design of these parts was modified to incorporate an interface to attach a gear segment that will drive the strut up and down. The gear segment was machined from a full round gear blank. Machining of the new trunnion halves is progressing smoothly and will be complete in early May. 

We outsourced several of the components required for the nose gear update. Normally we machine almost all of our metal parts in-house, but in the interest of accelerating the project, we decided to outsource half of the new parts. This allowed these parts to progress in parallel to the parts we are already making with our tools. 

Between the parts we are manufacturing in-house and the parts we have outsourced, we anticipate being ready to assemble and test the new design in mid May. Even though we have called this project a “refresh” to the nose gear, the scope of work was not trivial, given the number of parts that were impacted. We are excited about the new design and proud of how quickly we were able to develop a new solution based on lessons learned through physical testing.

In addition to manufacturing the new design, we also used the test stand to verify our CAD and finalize the nose gear door open and close mechanisms. Small brackets were bonded to each door along with Click Bond fasteners. The forward door hinges with the strut and moves with it as it opens and closes. The aft two doors open and close through a spring mechanism that catches the strut leg on the way up. It springs open as the strut leg comes down.

Sun n' Fun
The annual Sun ‘n Fun Aerospace Expo was held this past month in Lakeland, FL. Ryley made a quick visit to the airshow to meet face to face with a few of our suppliers. He also took the opportunity to meet up with our Florida-based remote intern, Michael Wirsing, who has been putting significant effort into our build instructions and supplying us with 3D printed parts.

Center Tunnel Box Work
The center tunnel box is nearly complete with the recent installation of the remaining connectors that will tie it into the wiring in the rest of the airplane. We used mil-spec circular connectors for each of the plugs and finished them off with shrink sleeving for better protection of the wiring. The last task to complete the box will be installing the firewall plug wiring for our two ECUs and the hardware needed to secure the box inside the airplane.

Instrument Panel Progress
We made several modifications to the instrument panel layout to align it with our initial VFR configuration. These modifications included adding cutouts and installing the startup switches, landing gear position indication lights, and the Airmaster propeller controller. These changes bring the panel closer to the renders we have shared in previous updates minus the addition of a second Garmin G3X display, GTN 650 NAV/COM/GPS, and GMC 307 autopilot controller. These modules will be added once we have progressed past flight testing and begin setup of the IFR configuration for the aircraft. In addition to the panel modifications, we installed the bulk of the wiring for this new layout and added mounts to secure the wiring. Next month we will be finishing the wiring for the newly upgraded 61 pin connector that ties the panel to the rest of the airplane along with the remaining components to finish off all of the wiring for the panel. 

New Intern: Sean Collins
In April, we brought a new intern onto the DarkAero team, Sean Collins. Sean recently received his Aerospace Engineering degree from Iowa State University and brings with him hands-on skills he developed through building competition solar cars and engineering composite wind turbine blades. Sean has jumped right into the fire with the rest of the team and started work on getting the nose gear drop test rig ready for tests.

YouTube
We released two new videos that showed some of our recent design and manufacturing challenges as well as day-to-day life in the shop. Links to these can be found below:

Beyond the Prototype - Design for Manufacturability | DarkAero 1 Nose Gear

Engineering and Manufacturing | DarkAero Shop Vlog | April 22, 2021

Oshkosh Plans
We have had a number of inquiries about our plans for AirVenture this summer. Our focus has been on completing the prototype and getting the aircraft into the air this year. Given where progress will be in July, we would have to disassemble and reassemble the aircraft to trailer it to the airshow. We see this as a significant distraction from our objectives so unfortunately we will not be bringing the prototype DarkAero 1 to AirVenture this summer. However, we will be at AirVenture in some capacity as a team, and we are planning some sort of social meet-up event where we can connect in person with anyone who is interested in our project. We will have more details to share closer to the event. 

Looking Ahead
Heading into May, we are pushing to finish up the nose gear refresh and complete the nose gear drop test. Work on the wiring will continue, with many of the major milestones for the harness reaching completion. The main gear has been on pause so we will be picking that back up as well.