Configurations and motor testing
With Kees we started Friday morning in setting up the tests. It went smoothly. We added some more precaution measures (rope limiting movement, and side positions) and a reinforcement bar. After testing the system with 14 V all was setup correctly.
Next, as we aimed to work with a slightly higher voltage than prescribed by the ESC we started a test with that: It was quite bad luck: a alarming sound of the ESC seemed to indicate it did not accept; also with the servo tester movements it did not, so that forced us to take out one pack of Lipo batteries with a reduction of 13.8 V. With 12 S the system started up nicely.
We tested the first direct drive Rotomax. That yielded good results 26 kg trust, prop 32x12. Noise is a real issue ( > 100 DB at 1 m). Although the motor and prop did neatly (no vibrations) we had the sensation of a hurricane moving through the lab. (for sure, all dust was removed!).
Then with lower voltage we had to test the belt drive. This one did also as expected. Noise was much lower and we had no vibrations. However as voltage was too low to get it in full performance we can say it will do as anticipated.
The first analysis is that the systems performed according to the simulation program used. Battery performance still needs to be analyzed. We stopped as battery voltage was too low to do meaning full co-axial rotor tests. Will do that coming week. In conclusion, may be prelim, we think that lower RPM’s are better and this means more no of motors, or the belt drive.
Testing carbon fibre tubes
Marko analysed the carbon fiber tubes, and they confirm close relation with the simulation program. Error margen is less than 5 to 10 %. So with this we feel safe.
Shape and canopy
The craft sketched is beautiful. After the tests on the configuration we will reveal the final shape.
Legal issues and safety
Planned is to discuss a number of pending issues with NRL. We hope to have a conversation with them soon!