The third phase of landing gear drop testing on the DarkAero 1 prototype commenced in October. Additionally, contract projects fulfilled through DarkAero Services advanced significantly with customer aircraft being completed and test flown.

Landing Gear Drop Testing
Validating the DarkAero 1 landing gear structures has involved drop testing the airframe across a range of pitch attitudes and drop heights in three main test phases. Each phase was designed to simulate different landing conditions. The first two phases both focused on level landing scenarios: in the first, all three landing gear touched down simultaneously, while in the second, only the main gear made contact with the ground. 

The third and final phase of drop testing began in October, with the airframe dropping in a nose-high attitude and only the main landing gear contacting the ground. This condition simulates flaring the airplane too high and stalling onto the runway at a high vertical descent rate. The test setup was guided by FAR 23.481. 

The test rig was reconfigured to position the airframe assembly in a nose-high attitude, and sand bags strapped inside the fuselage for mass simulation were adjusted to give the desired center of gravity position for the test. Testing proceeded in the same manner as earlier phases, starting with low initial drop heights and moving incrementally to higher heights. Video and accelerometer data were collected during each drop to reveal any trends and project what loads the airframe would experience at higher drop heights. 

The nose-high drop test is different from previous test cases in that the ground reaction load is purely vertical and does not include a drag component due to wheel spin up. This condition can occur when stalling the airplane onto the runway during a second impact after a bounced landing that already spun up the wheels. Even though it is an edge case, this scenario represents a challenging condition for the DarkAero 1 landing gear that must be explored.

The DarkAero 1 utilizes a trailing link suspension, and the behavior of this articulating landing gear arrangement varies depending on the aircraft pitch angle upon landing impact. The energy absorption in the landing gear comes from both the tire and the shock working together. The relative angles between the shock, trailing link, and ground heavily dictate how the shock and tire behave dynamically as a system. The geometry of the trailing link and shocks on the DarkAero 1 is designed to provide the best performance during hard landings with a drag load from wheel spin-up on initial impact. It was predicted that the absence of a drag load would alter the performance of the suspension, but it was left up to testing to verify the true numbers. 

Initial testing showed that the landing gear geometry would not provide sufficient energy absorption at a nose-high attitude with higher drop heights. To address this, a bolt-on bracket was quickly designed and temporarily installed on the gear strut to test the effectiveness of changes in shock angle. Subsequent tests with the new shock mount geometry confirmed that even small changes in geometry could significantly improve the landing gear behavior in nose-high impact conditions.

Enough nose-high drop attitude data was collected to guide the design of a more permanent geometry modification to the shock, trailing link, and strut. The modification includes a combination of changes to the trailing link angle and shock mount angle. These updates are currently being implemented and are expected to provide the desired level of performance across the full range of landing pitch attitudes.

To date, over one hundred airframe drops have been completed. While this is a large number, each drop serves a specific test objective. The landing gear behaves as a dynamic system, with tires, shocks, and airframe interacting in ways that are difficult to accurately predict in the absence of physical testing. The high volume of drops reflects both the complexity of the system and the validation required to achieve reliable performance across varied landing conditions with a new design. The drop testing campaign has led to over a dozen design improvements and refinements that were implemented in the prototype and will ultimately be carried forward into the production design. 

DarkAero Services and Team Growth
In parallel to DarkAero 1 development, contract engineering and manufacturing projects have continued to be fulfilled. While the specific details of these development programs are not public information, DarkAero’s involvement has ranged from design for manufacturing, CAD modeling, and trade studies all the way up to manufacturing multiple airframes and performing structural validation testing. Multiple aircraft development programs are underway, with both a new airframe completed and a separate aircraft program achieving first flight in October. 

The engineering and manufacturing capacity of DarkAero has been expanding as new engineers and technicians have been brought onboard and trained. The team continues to grow, and open positions are available for talented engineers and technicians. If you’re passionate about aerospace and want to design and build new aircraft, check out the DarkAero Careers page and apply today! Interested candidates can also inquire at careers@darkaero.com.

Looking Ahead
Nose-high attitude drop testing will continue in November with the objective of validating the landing gear geometry changes that were established last month.