system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: what are the benefits of a normal helicopter design vs a quadcopter we see on drones?
gpt
Simplicity, making a normal helicopter a quad copter would be really really really hard and complex.

That’s because helicopters use combustions engines running on aviation fuel, while quadcopter a uses electric motors.

so for a quad computer, the only moving parts are the spinning motor out on each corner. All that runs back to the center is wires, no moving parts.

A helicopter has a spinning shaft attached to the engine like how a car does. So if you wanted to doing 4 sets of blades with 1 engine, you’d need to figure out how to run spinning shafts through all for corners of the helicopter. 
 
Or you’d had to have 4 different engines, one for each set of blades, and figure out how to easily control the thrust each individual engine is producing.

Is that possible? Yea I’m sure a good engineering team with enough money could figure it out.

But when a helicopter with 1 set of blades works just fine 99% of the time, why make one that would be much more expensive to make and require a lot of maintenance to keep running?