A few months ago I wrote about my experiences building two qaudplanes. There have been quite a few ups and downs since then, including a couple of ‘walk of shame’ incidents. I’m sure many of you can relate.
I was quite happy with the performance of the Skywalker X8 quadplane but one issue that bothered me was that it didn’t fit in the roof cargo box of my car without removing the props. So being the clever person that I am, I thought I’d just use folding props as I had on the Darkwing prototype quadplane. Well, that was the beginning of almost six months of grief.
On the first takeoff attempt one of the folding props snapped off and the quadplane flipped over. The motors were spinning in the dirt and I wasn’t able to disarm it. Unfortunately, I was using T-Motors rated for 4S on 6S batteries. So the white smoke escaped, but this at least allowed me to grab the plane and disconnect the power. So what now? Rather than buy expensive replacement T-Motor motors I thought this might be a good opportunity to try some cheaper HobbyKing SK3 motors and try running the plane as I’ve seen most other builders do with one 4S circuit. This turned out to be yet another bad decision for as I didn’t take in to account that my wiring was not heavy enough for the additional current caused by lowering the voltage.
On the next test the wires became so hot that the power module disconnected, the ESCs over heated and the motors were extremely hot. Off to the work bench I went to correct this situation. With proper wiring installed, I had another go at vertical take off which went well. However, the entire system was still quite hot and the current was well over 120amps during vertical lift. I’m really not sure how other builders are achieving vertical lift of up to 6Kg with 4S motors and batteries as I don’t know many multi rotors of that size using that configuration.
So back to the bench again and this time I went back to T-Motors. As much as I hated to cannibalise the Darkwing, I just couldn’t afford to buy another set of motors. So now the X8 has T-Motors rated for 6S and a seperate wiring circuit for the vertical lift. Current draw during vertical takeoff is around 80A now and it flies great as a multirotor with plenty of authority and a hover rate of around 60%.
All of these tests put quite a bit of stress on the airframe and the wing joiners started to seperate a bit. Combined with using the wrong size spar during a test flight, a wing spar actually broke while banking the plane causing yet another crash. So after another walk of shame it was back to the bench for a lesson well learned. As the intro video shows, it was well worth it as the beast is back in the air now and I’m having a great time flying it.
Before all of this happened I was happily doing mapping tests with a Sony A6000 and getting fantastic results. Since that time I have purchased a MicaSense Sequoia multispectral camera which I’ll also be adding in to my tests. The big improvement though has been the addition of a companion Raspberry Pi computer so that I can do some machine vision precision landing tests with the Canberra UAV team as we prepare for the next Outback Challenge. Fortunately for them, I only do their photography rather than the building. But I’m having a great time and that makes it all worth while.
Thanks again to everyone here, my friends and the Canberra UAV team for all the fantastic help!