Welcome to new student
We welcome Chaofang, student aeronautical engineering, to the Humming Man Project. He will do his internship on a number of aspects of this project,  but the aerodynamic structure will be the focus of his work.

Working out the details of the external structure
Since we now have all material properties of the carbon fiber tubes validated, and know the configuration that we will use (12 props wit 6 pods), we are  working out the details: connections of tubes, with the motors,  with the fuselage, etc.. All effort is to give the structure the required strength, while adding minimal weight. We look at strength and stiffness and avoid frequency/vibrations due to resonance.  Fortunately we can do some computer simulations today!

More analysis on configurations
With the results of the tests on different  prop/motor configurations we have concluded some more relevant and interesting facts. Eg  coaxial props versus double props next to each other:  with the ratio prop diameter and the distance between the 2 props, of 2.7 and within the power range of 25 to 50 kg we find losses of 9 to 7  % respectively as compared to two independent rotors. This result is less negative as we anticipated as trials by others have been suggesting losses of 15 to 25 %. A possible explanation on the difference could be the ratio prop/distance. In our tests this is relatively high as compared with typical coax configurations. If we had time we could further test such relations; nice to do job!

Electrical system elaboration
We have been working on a charging system for the batteries. It is different for the tests as for a production type. But now it is time to have a good charger for the prototype that allows to charge the 15 S system.  The electrical system is being elaborated, it is a combination of 6 battery packs spread over the fuselage, but packs are connected to make one system.  One of the issues is where the connectors and fuses will be placed.

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                                                                                           Battery pack of 65 V one unit is 925 grams.

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Coaxial props: less losses as we anticipated.

Requests for belt drive systems
As the belt drive system did perform very good, with low vibrations and highest efficiency we are now seeing the possibility to manufacture it as quite a number of people already approached us for the Belt drive system. We will improve a bit on the design to make it even more robust, simpler in the manufacturing, yet lighter! Next week we can make an offer for those interested…

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Professional interest in purchasing the belt drive: i=3.16 width now 60 mm; we can do with 40 mm.

 
Fuselage decisions next week!
We hoped to hear from the people involved in the fuselage building this coming week!

Website renewal
There is scope for improvement for our current Website. We are now working on a more professional version.