The remaining ground tests on the DarkAero 1 prototype continued in April, with the team focused on the main landing gear drop tests. Additionally, the recent acquisition of a new CNC mill increased machining capability for current contract manufacturing projects and upcoming kit production.
The lifting fixture for main gear drop testing was developed in April.
Landing Gear Drop Tests
A remaining validation task before moving into flight testing is the main landing gear drop test, which is performed to prove the landing gear can withstand a range of severe landing load conditions without damage. There are different ways this test can be conducted, but the method that will be used for the DarkAero 1 prototype will involve lifting the fuselage and landing gear assembly and dropping it in a controlled manner from a target height.
The nose landing gear was drop tested using a fixture independent from the airframe, but the main landing gear will be tested in connection with the airframe since this larger assembly is partially integrated into the airframe structure. Similar to how the nose gear drop testing was conducted, the main gear tests will progressively increase in drop height as confidence is gained in the test setup. The final target drop height will match worst case level landing loads specified under FAR Part 23 for certified aircraft.
Lifting the aircraft will involve the use of an aluminum frame that connects to the engine mount and main landing gear mount points. The frame prevents point loading of the composite airframe structures and serves as a secure lift interface that is more repeatable than using lifting straps around the fuselage. Since the prototype airframe will be used as the test article, the test cases will be scoped to ensure that the fuselage remains airworthy after the test is complete. The engine and propeller will be replaced by a mass simulator during the drop test, and the wing will be replaced by a stub wing that will only span the width of the cabin and close out the bottom skin of the fuselage.
Other design aspects that will be explored through the drop testing campaign will include the energy absorption and rebound damping performance of the gas springs and proof loading of the forward bulkheads that support the nose landing gear.
Significant progress was made in April on developing the test setup and pulling together the test hardware. The team is eager to work through the range of test cases in May. Completion of the main landing gear drop tests will mark a major milestone on the road to flight testing.
Control System Refinement
Tests continued on the DarkAero 1 prototype control system. Previously, testing was limited to only loading one side of the flight controls up to the control stick, but for the final phase of testing, the combined load of left and right control surfaces was applied to simulate complete aerodynamic loading conditions. For the ailerons, the full load revealed that changes to the torque tubes would be required prior to moving into flight testing. After exploring several options including reworking the carbon fiber aileron torque tubes, the quickest path agreed upon was to redesign and manufacture the aileron torque tubes from stainless steel. Work on these components has already commenced, and the new parts will be tested in May.
Load was also applied to both flap control surfaces to assess full aerodynamic forces. These tests have been promising so far, but they revealed that additional reinforcement would be needed in the areas that support the flap control linkages.
Increased Machining Capability
For the past couple months, the team has been testing and evaluating the new Tormach 1500MX CNC Mill. This is the latest offering from Tormach, and it was only recently unveiled to the public in April. Adding this machine to the arsenal of tools at DarkAero has provided a measurable increase in machining capability, and it has already been put to work manufacturing parts for the DarkAero 1 prototype, as well as a number of molds for contract manufacturing projects.
Updated stainless steel parts for the main landing gear through different stages of machining on the 1500MX.
The majority of the machined metal parts on the DarkAero 1 prototype were made using the Tormach PCNC 1100. Although this machine was capable of making parts for the prototype aircraft, it was best suited for a prototyping environment where longer cycle times would not cause a bottleneck in operations. As the project transitions from prototype development to kit production, machining many parts for customer kits demands a more capable CNC machine.
The 1500MX provides increased machining volume and more power for rapid cycle times, as well as a number of features for increased automation in a production environment. More details on the new machine were discussed in the latest video on the DarkAero YouTube channel, which can be viewed at the link below:
Courses
Through the courses at DarkAero, hundreds of students from beginners to professionals have accelerated their progress building experimental aircraft, eVTOLs, drones, UAVs, boats, racecars, electric vehicles, motorcycles, bicycles, and military hardware. The next session of the DarkAero Aerospace Composites Course will be held on May 16-17. The course is for anyone who wants to understand how to create composite components and develop the hands-on skills to build them.
Sign up for the May session of the Aerospace Composites Course using the link below:
The next session of the DarkAero Aerospace Mold Making Course will be held on June 13-14. This course covers an often overlooked aspect of building high-quality composite parts, which is how to make high quality molds. This course complements the Aerospace Composites Course, but each can be taken independently. Sign up for the next session of the Aerospace Mold Making Course using the link below:
DarkAero Growth
DarkAero has been growing to accelerate flight testing of the DarkAero 1 prototype, transition to DarkAero 1 kit production, and expand engineering and manufacturing services. The capability of the team at DarkAero has been increasing as new engineers and technicians join in on the DarkAero 1 and other aircraft DarkAero is involved in developing. Additional capacity will be added to the engineering team in May, and interviews will take place to identify more engineers and technicians that are a good fit for the team. If you’d like to join DarkAero, check out the DarkAero Careers page and apply today! Interested candidates can inquire at careers@darkaero.com.
Looking Ahead
In May, progress will continue on the main landing gear drop tests and control system tests. Expanding the team and getting new team members up to speed will also remain a primary focus.
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