Above: Producing 41.5 kg of trust, with 7.6 kW. First results are in line with expectations/simulations. Prop 48/12, special design.

Thanks to all contributions
As a team we receive also highly valuable input of many people, who are experts in fields that we also need. For example from Reidar, Antony, Job, Alex, Kelly, Forrest and many others. We highly appreciate your contributions!

Configurations testing
This week we did try some more tests and improved on the measuring equipment. However the 15 S batteries only arrived on Thursday and we had to change connectors. All minor stuff but time consuming as these gold plated connectors of such size are not found commonly.

Today we tested the system with the 15 S batteries starting voltage was 62.5 V and at full power (140 Amp) it reduced to 54.7 V. At that power it delivers 41.5 kg of trust, which is a first indication. As compared to the calculations simulation software it is in line with the more optimist output. But if we see that this is the max trust we should have 7 motors to lift the 300 kg. Or accept little less total trust of  250 kg. It feels better to stay on the safe side, so 8 could work. We hope to come with coaxial prop results next week.

2

Batteries making about 16% of total battery volume. we use 8 Amph 5 S nano Hobby King.

Shape of craft
This week we had visits to company in Karlsruhe, Germany and in Duiven, the Netherlands on the shaping of the craft. We will soon have an offer for the canopy!

Development of Airbag parachute
With Reidar we talked about the airbag parachute idea.  He send us a text that we want to share: When flying hanggliders we often get into bumps and variations that takes the variometer beyond 2 m/s vertical speed for short moments. If the measurement is based on barometric pressure like our variometers (we use the modern Naviter Oudie 3) then there must be some filtering of fast air pressure change from disturbance. Alternatively the measurement can be based on a laser or radar based sensor that measures distance to ground. Also add the manual deployment. During test flights a remote standing “safety person” that can deploy the chute via RC. Often the pilot is very busy trying to control the swirling airplane. Some accident scenarios hovering machines can spin around a bit before falling down. Like if one of the props quits there will be some unbalanced swirling before tipping over and falling. Pilot and safety person will in those cases be faster than any automatic deployment.

Baby steps: testing the craft
Also we discussed the idea of testing: this is Reidar’s valuable contribution:
A lot of the early test flights will be very low altitude and safety system will be teethering in various forms. Just tie the thing down into either lines or rails to test the various functions one by one. Like when testing motors and propulsion systems then just let the drone be movable up and down on rails so not have to think of stability. Then add various functions in baby steps towards all functions at work at same time. Baby steps and a planned progressed program is the thing. Isolate every function and verify before combining functions. Early days test-flight crashes were typically that several things were not good at same time and in combination it made the thing hopeless to fly for a real takeoff attempt.