After going through a dozen wood props (they seem to splinter the minute you stare too hard at them), I decided to try out some carbon props. With the idea of reducing the RPM (and noise) of each prop, I ordered some 22x12 from Iris Engel.
After receiving the props, I went ahead and CNC machined the inverse shape of the prop shaft, 6 mm deep, so that I would not get issues with props slipping (see: Carbon Fiber Prop Bulk Order)
Doing some burst thrust tests against a wall, I got about 330A of current at max. throttle. The noise is generally lower pitch than wood props.
I went ahead and did a couple of flights. Everything ran smoothly until… about 10 mins in (and with 100-150 A of continuous current usage, which is pretty low) the motors all stopped rotating. In both cases, I had to perform un-powered landings.
To explain clearly: the motors just stop and go into the “beep-beep” mode. The throttle still shows “armed”. Doing a “disarm”/“arm” cycle has not effect. The only way to re-arm the system is to turn the big red knob on the side of the PPG (which can’t be done whilst flying).
To make sure nothing was damaged, I reverted to wood props, and sure enough a couple of flights went smoothly, without power cut-off.
I am guessing that the HUB or ESC do not like the 22x12 props, but I wonder why they shutdown when the current draw is only 100~150A (this is pretty much the same current I normally draw with the wooden props). Is there some setting in the HUB that can be changed to allow me flying with these (pretty sweet and expensive) carbon props???