2022 Mejzlik Annual Update
It's been a while since our last quarterly report was published. Since we have been busy in the meantime, a lot has happened that we'd like to share with you. The most important message is that our main mission remains the same and step by step we are getting closer to our goal of becoming the number one propeller manufacturer.
New simulation software (PyProp)
Detailed simulation is an essential part of the design of a new propeller. For that reason, we purchased new software that expands the capabilities of our existing simulations. We can now optimize the noise and performance of an single or coaxial propeller. At the same time, we established a close partnership with an Israeli company engaged in research and development in this area.
The software allows us to address the following use cases:
- Acoustic and performance simulation for 3D models
- Subsequent optimization in terms of performance, acoustics or both for a specific engine/motor
- Simulation of both multi-copter and fixed-wing propellers
- During the optimization phase hundreds of designs are calculated and these can be compared with the final one
Structural Analysis and NDI
Until now, we have processed FEM analyses externally in cooperation with partner companies. We are now actively working on being able to process FEM analyses in-house. This will speed up the whole process. The procedure is such that, in the first step, an FEA model of the propeller is created, and then the proposed propeller structure is entered into the analytical Software. We typically use Fusion 360 simulation for isotropic materials and Nastran for composite analysis. The analysis consists of a stress part, deformation and natural frequency analysis.
Once the prototype is built, we use a combination of destructive and non-destructive testing methods to verify the consistency of the design. For NDI, we use a newly purchased ultrasound tester. At the same time, 3D scanning is performed to verify the OML tooling and the first manufactured pieces.
Professional Propulsion Systems (PPS)
As part of the PPS project, we cooperate with several manufacturers of high-end engines and ESC (electronic speed control). We then test their equipment with our OST multi-copter propellers. The entire drive unit is tested in Mejzlik laboratories using calibrated test equipment and transparent methods. The resulting data is published on our website. If the customer chooses a suitable unit, he can use the measured values in different combinations of engine and propeller. This data can be used for the initial optimisation of the propulsion unit or when designing a new platform. The customer can also compare the parameters of their current solution and possibly quickly replace the currently used unit.
Current partners who cooperate with us within PPS are Maxon, Scorpion, Plettenberg, Sobek, and Alva. More will be added gradually.
Folding propeller from Mejzlik Propellers
Based on several factors, we decided to develop our own folding propeller. The main emphasis during development was placed on safety and reliability. Our solution is based on the analysis and testing of other competing propellers. The main advantage of the Mejzlik propeller is the exceptional safety of the hub, which is connected to the engine on both sides and is therefore better secured in the event of a problem. Propeller blade supports are more robust and thus more resistant to falling off. Nevertheless, the minimum weight of the entire propeller was maintained. The screws used have a high safety factor.
Propellers are delivered assembled and balanced for vibration-free operation.
At Mejzlík Propellers, we are constantly redesigning the manufacturing process to achieve certification requirements. Close cooperation with external advisors from the FAA and EASA also helps us to achieve this goal. One of the innovations is a bar code that identifies each propeller during the production process. Thanks to this, we can trace it during the individual steps of production and carry out continuous quality control. Other innovations are the improvement of storage management or the optimization of the consumption of cut material through automatic precise cutting.
New production line
One of the biggest innovations at Mejzlik Propellers is without a doubt the new production line based on Pre-Preg materials and hot-press. The main advantage of this solution is the repeatability of production and a shorter curing time due to high temperatures for curing. By shortening this cycle, we can scale production better compared to standard wet production.
The resulting carbon made from prepreg ensures much more efficient use of epoxy and is characterized by its lower weight with the same structural performance. A whole new floor will be built for prepreg production during the first half of 2023. The total area of this part of the production will be 1000m3 and will meet the requirements and standards of the FAA and EASA for aviation composite production.
The new test facility includes a 110-kilowatt overspin test facility with a reduction gear. This makes it possible to test propellers up to 2.8 m in length at a maximum speed of 9500. Other possibilities of use are for static performance tests of the drive in combination with loads from 500g to 300kg and the drive of a 30 kW AC/DC power supply. A semi-anechoic chamber was constructed for basic acoustic measurements.
We are able to test the entire drive from our customers. We compare the measured results with the values measured for our stock propellers within PPS. All results are available in the overall final report. Utilizing in-house testing capabilities helps to keep more of the development processes under one roof. Subsequently, we can supply documents for certification such as durability tests, tip deflection tests, overspin and over-torque or centrifugal load testing.
Production of UAM propellers
This year we managed to get several orders for the production of 2-3m propeller prototypes. We have added 60, 70 and 80-inch propellers to our OTS propeller portfolio. A curing oven built for propellers up to 3 meters can cure using automatic curing cycles up to 180 degrees. The methods used include CF infusion tooling using a high precision CNC master tool model, prepreg propeller materials.
The construction of an internal testing laboratory for overspin, endurance, structures, noise and material fatigue in accordance with EASA/FAA is currently in process.
In cooperation with various manufacturers of UAM platforms, we are working to better understand the future requirements that will be necessary for certification.
We are working on a propeller anti-icing solution together with UBIQ Aerospace.
Working on implementation of metal Leading Edge Protection to multicopter and fixed-wing UAVs, first solution implemented in 2022.
Increasing the repeatability of our production – CNCing of foam cores, prepreg materials, new non-destructive testing methods.