mysql
Registered
It's complicated. To make it simpler, lets assume for a moment the frame weighs the same for 4 motors and 8 motors. So the only difference is the additional motors and speed controller. Motor is ~72g each. ESC is ~40. So we're talking around 450 grams more for doubling the number of motors on the craft. That's twice the thrust, but also twice the battery drain. However, because they share weight in terms of basic framework, flight controller, etc, you end up with better power to weight ratio.
So... sure the frame will weight more, and sure the motors add weight. And you're going to need a larger battery to boot. But with better power to weight, your motors can run at lower rpm than they would if you tried the same cargo on 4 motors...
This is where it gets complicated. Your larger frame can have larger propellers. This means better lift. You can also run with motors that have lower rpm (better efficiency). It's not really a direct comparison.... my quad frames tend to do anywhere from 8 to 10" propellers. My new octo can do 12" (limited only due to the way I did my arms and their length).
It's kind of like smart phones. Each new generation has about the same battery size as the previous, but each gen has faster cpu and more ram. Yet batt life is the same or better. The reason is they can process more things faster, so they don't run hot as long.
