In June we were able to fully build up the nose gear, attach it to the fuselage, and test more of its functionality as a system. We also worked through interfacing the electrical system wiring harness with the firewall connectors.

Nose Landing Gear
Work continued on the nose gear this past month with much of our focus put into assembling and testing the functionality of the whole system. We outsourced the manufacturing of the mount arms that support the nose gear strut, and these parts were received in June. The mount arms are made up of four pieces that, once fully assembled, act as both a gearbox for the retract mechanism and structure to support the gear landing loads. We were pleased with how these parts turned out from the supplier and also pleased with how they fit together with the parts we manufactured as we moved into the assembly tasks.

One of the assembly steps included riveting the mount arms to the engine mount uprights. There were a few dozen rivet holes that needed to line up between these components, so when everything fit together correctly during our test fit up, it gave us the confirmation we needed to proceed into permanently riveting the arms to the uprights. 

With all the necessary nose gear parts assembled, we were able to install the nose gear in the fuselage. Part of this process involved installing hard points in the nose gear wheel well to receive the fasteners for the drag link mount and the threaded ends of the emergency gas springs. The hardpoints were made from phenolic disks covered with additional reinforcing plies of carbon fiber. The phenolic disks replaced the honeycomb core in the wheel well bulkheads to prevent bolt clamp loads from crushing the panel and to handle bolt shear loads. The reinforcing plies of carbon fiber transfer the loads from the phenolic disks into the panel skins. Once the hardpoints were installed, we were able to drill holes in them and bolt the nose gear in place.

We ran our first set of retract tests by cycling the nose gear up and down by hand. These were performed with and without the emergency gas springs installed. We were also able to verify functionality of the mechanism we designed to disengage the drive motor from the strut during an emergency extend event. We had several remaining questions from when the design was completed in CAD. These mostly revolved around how the system would function and how the system would “feel”. The “feel” questions were hard to answer in the CAD world but with everything fully assembled together, it was easy to see that it behaved as expected and the whole system felt solid. When we were finished with our preliminary tests, we moved on to driving the gear strut up and down under electrical power. We are excited to report the drive motor and gearbox have plenty of torque, despite the compact size of the system.

One area of the nose gear design we had yet to resolve was the limit switches that stop the gear drive motor when the strut reaches its ends of travel and also provide data for the gear position indicator lights on the instrument panel. There are four limit switches in the system that indicate whether the strut is up or down and whether the gear lock is latched or unlatched. We were able to arrive at a mounting solution for the four switches by attaching them all to the drag link mount plate. This allows the mount plate and switches to be assembled on the workbench as a module and then installed into the nose gear wheel well rather than installing individual switches in the wheel well. The last piece of the nose gear installation will be integrating the drive motor and limit switches with the rest of the aircraft electrical system. This will continue after we perform the drop test on the nose gear. 

Electrical System
In June we worked through the challenges of passing the electrical wiring harness through the firewall. Each wire bundle that runs through the firewall uses a MIL-SPEC circular plug connector mounted on an interface plate. There were a number of potential interferences that we needed to avoid to safely route the wiring through the firewall to the engine and prevent wire abrasion. To resolve these interferences, we widened the existing firewall hole for these connectors and iterated on the connection layout using a series of mockup interface plates. After settling on a layout for the plate that eliminated interferences, we were able to determine the wiring lengths for the remaining ECU connectors that run out of the center tunnel avionics box and into the firewall. With these connector positions finalized, it allowed us to proceed to finalizing the wire routing and connector wiring on the firewall side in order to ultimately power the airplane and run the engine.

YouTube
This month we put together two videos featuring some behind the scenes airplane progress, which were released to our Mach 2 YouTube community members. YouTube community memberships offer a way to support the DarkAero project and see more frequent updates and insight on our build progress between public updates. If you’d like to join this community and get access to bonus video content, click the join button after visiting the video links below: 

Last Parts to Assemble the Nose Gear | DarkAero Shop Vlog | June 11, 2021

Wrapping Up Nose Gear Details | DarkAero Shop Vlog | June 25, 2021

As we have worked through building up and testing the nose gear, we have collected a lot of video footage. We have a few new public YouTube videos we are working on that showcase different aspects of the nose gear progress and functionality. Stay tuned as these will be released publicly over the next few weeks!

In the News
Kitplanes Magazine released part one of a two-part article about DarkAero. Thank you to Eric Stewart and Kitplanes Magazine for the excellent write up! We feel both honored and excited to be featured in Kitplanes! The article can be viewed here: 

DarkAero Keeps It Light

Looking Ahead
In July we will be shifting focus to the main gear. Our next big push is to get the hardpoints for the main gear installed, assemble the main gear, and get the airplane resting on all three wheels! This will likely consume a similar amount of time as our recent nose gear efforts, so we expect to be working on the main gear through July and August.