Progress on the DarkAero 1 prototype continued in April. Nose gear drop testing was completed, additional main gear retract hardware was installed, and sump tank testing was conducted.

Nose Gear Drop Testing
The nose gear was drop tested in April and passed the requirements specified by FAA Part 23 standards for emergency landing conditions. Although the design went through a considerable amount of analysis, the landing gear performance still needed to be verified through physical testing. The goal of the testing was to simulate hard landings in a safe and controlled manner before proceeding into flight testing. 

The test results indicated that the shock was compressing and absorbing impact energy while minimizing the forces that would be experienced by the rest of the airframe and occupants. The testing also proved that the landing gear could sustain a high speed, gross weight emergency landing condition without experiencing any permanent deformation. Additionally, it was demonstrated that the design dissipates absorbed energy and dampens rebound. The FAA does not explicitly require that landing gear limit rebound, but it is important that landing gear are designed so they do not return the absorbed landing energy to the airframe like a compressed spring, causing the airplane to bounce on landing. Incorporating a damping mechanism to minimize bouncing was considered an essential safety requirement. 

Leading up to the final drop test, several tests with less weight and lower drop heights were conducted. These lower drop heights were more representative of normal landings and demonstrated the desired response of the landing gear. The shock compressed and kept the tire in contact with the ground, indicating that it is absorbing the landing energy and dissipating it, rather than springing back and bouncing.

This drop testing was a major milestone for the project and marks the completion of the bulk of engineering work for the nose landing gear. Work is wrapping up on the main gear retract mechanisms, which will allow main gear drop testing to be conducted next.

Installation of Landing Gear Electrical System
After the completion of bench testing for the landing gear electrical system in March, the three gear retract modules were fabricated, wired, and installed into the DarkAero 1 prototype. 

The design for the retract module frame was improved to make it more manufacturable and easier to install, and these changes were incorporated into all three modules since they are all identical. 

A few wiring tasks remain to fully connect the retract motors and install the gear lock release solenoids. Full retract testing with all three gear struts is rapidly approaching. 

Sump Tank Tilt Testing
Fuel systems and fuel tank designs can sometimes have unexpected behavior, so a plan was developed to prove out much of the fuel system architecture while safe on the ground. Sump tank testing began in April with the initial test indicating the bulkhead fittings, vent ports, and check valves function as expected. A small leak was detected in the sump drain port, but this will be corrected before further testing proceeds in May. The remaining sump tank tests will explore fuel flow during edge case conditions that can occur during uncoordinated turns and steep pitch attitudes. 

Courses
Session 17 of the Aerospace Composites Course and Session 4 of the Aerospace Mold Making course were held at the end of April. Students in these courses were seeking composites knowledge and skills to tackle projects ranging from new engine cowlings for Radial Rocket kitplanes to research programs for the Army Corps of Engineers.

The next session of the Aerospace Composites Course will be held May 19-20 and the next session of the Aerospace Mold Making Course will be held on June 1-2. Sign up for an upcoming session or learn more about the courses using the links below: 

Sign up for the DarkAero Aerospace Mold Making Course

Sign up for DarkAero Aerospace Composites Course

DarkAero Aerospace Composites Course Online + SAAA
In April, a partnership was announced between the Sport Aircraft Association of Australia (SAAA) and DarkAero to provide SAAA members a discount on the online version of the DarkAero Aerospace Composites Course. The course will help SAAA members achieve success in their composite kitplane projects by answering questions like: 

How do I pick the right fiber and fabric weave? 
How many layers of cloth does my composite part need?
How do I achieve a smooth surface finish on my composite parts?
How do I convert a metal design to composite? 

If you are also seeking answers to these types of composite questions, consider enrolling in the course. More information about the online version of the DarkAero Aerospace Composites Course can be found here:

DarkAero Aerospace Composites Course Online

Learn more about the SAAA and how to become a member here:

SAAA Website

DarkAero Aerospace Mold Making Course Online
With the success of the DarkAero Aerospace Composites Course Online, the Aerospace Mold Making Course will be brought to a broader audience through its own online version in May. The course consists of many lessons covering mold design and fabrication topics ranging from how to select the right material for your mold to multi-section mold pattern construction using a CNC. The lessons include real world examples from the DarkAero 1 showing how to design and construct production-grade molds for making high-quality composite parts.

Final review is currently being done on the course. To join the waitlist and be notified as soon as it's released, use the link below: 

Join the Waitlist for the DarkAero Aerospace Mold Making Course Online

YouTube
Two new videos were released on the DarkAero YouTube channel in April. These included a discussion on the feasibility of an electric version of the DarkAero 1 as well as deep dive into the work that has gone into the design and testing of the nose landing gear:

The Engineering Challenge of Electrifying Airplanes

Engineering Softer Landings (Drop Testing)

Looking Ahead
In May, the team will be focused on testing the retract system for the landing gear as well as drop testing the main landing gear. The sump tank testing will continue and a list of miscellaneous systems tasks are being worked through prior to first flight.