DarkAero, Inc

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. Read more in our October update here: https://lnkd.in/gDpWvWNt

Each phase of drop testing the DarkAero 1 prototype has been designed to simulate different landing conditions. The first two phases both focused on level landing scenarios: in phase one, all three landing gear touched down simultaneously, while in phase two, 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. Read more in our October update here: https://lnkd.in/gDpWvWNt

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. 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. Read more in our October update here: https://lnkd.in/gDpWvWNt

Outside of our YouTube channel and social media pages, we consistently publish a monthly newsletter on work at DarkAero! Our website was recently updated to better chronicle these articles. Check it out here: https://lnkd.in/gnk8gF9X

Drop testing the main landing gear for the DarkAero 1 continued in September, with the second test configuration reaching completion! Full post below.

There have been a number of major projects moving in parallel at DarkAero that we haven't discussed publicly much, so we want to share more about our progress in three key areas: ground testing the DarkAero 1 prototype, expanding our manufacturing capabilities, and growing our team. Full post below.

Hello everyone! We will be at EAA AirVenture this week all day Wednesday, July 24 at the UL Power booth 633 in the Homebuilt Aircraft Display section. Come swing by and talk airplanes with us!

Over the past month, landing gear drop tests progressed through increasing drop heights at the full target weight. The aircraft was dropped in a nose down attitude to simulate a level landing with inclined reaction loads. Inclined reaction loads are the sum of vertical ground impact forces and horizontal drag forces from spinning up the wheels during landing. Horizontal forces had previously been generated during nose gear drop tests by spinning the wheel assembly, but this method was not used for the full airframe drop test due to the complexity that would have been introduced in trying to spin all three wheels simultaneously. Pitching the nose down during drop testing achieves a result similar to spinning the wheels by generating loads that contain both horizontal and vertical component forces relative to the airframe. Platforms were built under the main wheels so that all three landing gear would impact simultaneously in the nose down drop attitude. Additional test points are planned to simulate nose high attitudes with the main gear contacting before the nose gear, with the most extreme pitch attitude representing stalling the airplane onto the runway. The higher drop heights provided more insight into the shock travel and rebound damping. Initial test results were shared with our shock manufacturer to better inform the baseline shock pressure and damping parameters. Another lesson learned through drop testing was that the tires initially selected for the main gear were excessive in their load capability, and the tire pressure was run unnecessarily high. The main gear tires were swapped out to a model better matched to the airframe weight and better optimized to operate at lower pressures. Lower tire pressures will enable better impact energy absorption for typical weights the DarkAero 1 will operate at. Data obtained from accelerometers attached to the airframe showed the loads experienced by the airframe during drop testing were higher than initially predicted. Prior to advancing to the next round of drop tests, the team has elected to install additional reinforcement plies in the highest stress areas where the landing gear interface with the airframe. These modifications will help increase the structural safety margins and better transfer loads from the landing gear to the rest of the airframe.

DarkAero is hiring! Check out DarkAero.com/careers for more info.

Our post last week about the DarkAero 1 main landing gear suspension seemed to spark a lot of curiosity, so we wanted to share more about the design. Aircraft landing gear suspension must be designed to handle the reaction forces generated during worst case landings and absorb and dissipate the impact energy of the aircraft as it touches down. The DarkAero 1 achieves this design goal through the use of a trailing arm suspension in combination with an oil damped air shock. The main wheels are mounted on an arm that trails behind a pivot point allowing the wheels to swing both up and aft in response to impact forces from the ground and drag forces generated from spinning up the tires. This minimizes the loads transmitted to the rest of the airframe, and the oil damped air shock helps minimize any rebound to reduce the likelihood of the aircraft bouncing back into the air after touchdown. This combination of geometry and response inherently helps achieve smooth landings even in less-than-ideal landing conditions The trailing arm configuration has proven successful and is widely used on countless aircraft. One of the most notable examples of a trailing arm suspension can be found on the F-18, which is designed to land on the decks of aircraft carriers. While the DarkAero 1 isn’t designed for carrier deck landings, the trailing arm architecture is utilized because it provides a compact arrangement for absorbing and dissipating landing impact energy. Comment below if you can name any other aircraft with trailing arm suspension!