4 ms·

Max output of a motor is constrained by weight, or more specifically, its ability to dissipate heat. Racing quads generally use 30-40 gram motors. The top rac

Max output of a motor is constrained by weight, or more specifically, its ability to dissipate heat. Racing quads generally use 30-40 gram motors. The top racing motors these days produce 1.6kg of thrust at max output and consume 40 amps of power in the process. It's not difficult to produce a quad under 500 grams. 4 motors would produce 6.4kg of total thrust for a 500 gram quad for a nearly 12.8:1 thrust/weight ratio at a 160 amp current draw. A few years ago a 4:1 thrust/weight ratio was considered pretty good. 160 amps might be a stretch, but it's not uncommon to get >100A out of a 1300mah battery. All that is pretty crazy, but I think the more interesting bits are in the open source efforts around flight controllers and speed controllers.

bradfa 9y ago
With those kinds of currents, it'll be interesting to see if point of load DC-DC converters become integrated into the motors themselves so as to reduce the wiring requirements for distributing the power to the motors. The batteries will need to stack more cells in series to support this but I wonder at what currents the wire gauge, and hence weight of the wires, become a big concern. Maybe modern quads already do this?
- halbritt 9y ago
  Wire runs are so short and peak current is so brief that it effectively doesn't matter. Most folks run 14AWG between the battery and the power distribution board. PDBs are generally made with 2oz copper and wide traces to accommodate the current, from there, the total current load is divided by 4, assuming that's how many motors or running.
  - jsjohnst 9y ago
    > Wire runs are so short This! The length of wire makes a huge difference in rated capacity.
eltoozero 9y ago
All of the flight controller development I see is just circuit optimization for LC filters (cleaner video), integrated OSD, smaller 20mmx20mm footprint for micro-builds, hardware-wise anyway. There is a good amount of competition in the cleanflight/betaflight/raceflight firmware arena and there is outstanding hardware support for an amazing number of FC boards. Speed controllers are playing songs now, months after my bro did some ESC assembly hacking to get his playing the first few bars of the doom theme, it’s just a feature now. Frankly I think the powerful open-source FrSky gear, the taranis TX and the OpenTX movement has made the biggest impact on the RC scene overall raising the feature bar and lowering the price point significantly over spektrum and futaba gear.[0] [0]: https://www.frsky-rc.com/product/taranis-x9d-plus-2/ https://www.frsky-rc.com/product/taranis-x9d-plus-2/
jsjohnst 9y ago
160amps would be a real stretch for the weight requirements. I’ve pulled 400amps consistently before off a 6C battery under 4lbs, but getting nearly half that in under 1/4 of the weight seems a bit out of reach for existing tech unless you don’t care about exploding batteries.
- halbritt 9y ago
  Late reply, I know. The folks pulling down 160 amps are racing and don't care about exploding batteries. In fact, they expect to.

bradfa 9y ago

With those kinds of currents, it'll be interesting to see if point of load DC-DC converters become integrated into the motors themselves so as to reduce the wiring requirements for distributing the power to the motors. The batteries will need to stack more cells in series to support this but I wonder at what currents the wire gauge, and hence weight of the wires, become a big concern. Maybe modern quads already do this?

halbritt 9y ago
Wire runs are so short and peak current is so brief that it effectively doesn't matter. Most folks run 14AWG between the battery and the power distribution board. PDBs are generally made with 2oz copper and wide traces to accommodate the current, from there, the total current load is divided by 4, assuming that's how many motors or running.
- jsjohnst 9y ago
  > Wire runs are so short This! The length of wire makes a huge difference in rated capacity.

eltoozero 9y ago

All of the flight controller development I see is just circuit optimization for LC filters (cleaner video), integrated OSD, smaller 20mmx20mm footprint for micro-builds, hardware-wise anyway. There is a good amount of competition in the cleanflight/betaflight/raceflight firmware arena and there is outstanding hardware support for an amazing number of FC boards. Speed controllers are playing songs now, months after my bro did some ESC assembly hacking to get his playing the first few bars of the doom theme, it’s just a feature now. Frankly I think the powerful open-source FrSky gear, the taranis TX and the OpenTX movement has made the biggest impact on the RC scene overall raising the feature bar and lowering the price point significantly over spektrum and futaba gear.[0] [0]: https://www.frsky-rc.com/product/taranis-x9d-plus-2/ https://www.frsky-rc.com/product/taranis-x9d-plus-2/

jsjohnst 9y ago

160amps would be a real stretch for the weight requirements. I’ve pulled 400amps consistently before off a 6C battery under 4lbs, but getting nearly half that in under 1/4 of the weight seems a bit out of reach for existing tech unless you don’t care about exploding batteries.

halbritt 9y ago
Late reply, I know. The folks pulling down 160 amps are racing and don't care about exploding batteries. In fact, they expect to.