There is no single large collective pitch rotor or tail rotor that we are all use to seeing on a conventional RC helicopter. These propellers are fixed pitch, two will spin clockwise and the other two will spin counter clockwise. By precisely and accurately spinning these four propellers at different speeds, all the common directional movements of a standard helicopter are attainable - Hover, forward/backward movement, left/right movement, and yaw (turn rate) movement.

There are certainly other incarnations of the quadrotor design using as little as 3 propellers arranged in a triangle configuration up to six arranged in a hexagonal configuration and even eight (Octocopters); but for ease of explanation, I will stick with the quad variety as it is the most common and if you do end up getting this type of RC helicopter, most likely what you will be starting out with.

How Do They Work?

The reason RC quadrocopters are fairly new on the scene is the complex and rather heavy computing/processing power required to accurately control these 4 propellers to not only move the heli about, but to keep it stable. Inherent stability as I mentioned is very good, but directional control stability was the single largest hurdle that had to be overcome and only because of today’s solid state gyro and accelerometer technology, efficient and fast responding brushless motors, coupled with small micro processors to deal with the hundreds of calculations and control commands every second, can these things fly at all.

RC quadrocopters are not that performance minded and certainly are not capable of any fancy aerobatics mostly due to the very taxing computing power to just keep them airborne and the fact they use fixed pitch propellers making sustained inverted flight impossible. Times are changing however as lighter and more efficient processing power and electronic sensors become available making some fairly aggressive 3D flight possible and accurate – have a look at this video and you’ll see what I mean.

This level of performance is still in the development stages, but it shows what a quadrocopter is capable of and what might be available in the near future. In fact Blade has just come out with a micro quad rotor (the mQX) that can do basic aerobatics for under $150.00. Here is my full review on it - an outstanding little quadrocopter.

As I have been saying, the level of electronic sophistication and programming algorithms required to keep these things airborne is remarkable and I often call them "aerial robots" since in actuality you are not flying or controlling them like a conventional RC helicopter. You are basically just telling them what to do and the electronics and programming are 100% responsible for the actual flying – they really are amazing little machines.

Does A Quadrocopter Make A Good First RC Heli?

Yes, these do make a wonderful first RC helicopter if you want the easiest flying experience available to start with and don’t really care about true single rotor RC helicopter flight, flight characteristics, or the feeling of being in true control.

Remember, most of these quad rotors are essentially flying robots and do all the hard work for you so all that is required on your part is to give directional commands and the quadrotor heli will obey. They won’t fly past their programming parameters so it is essentially impossible to get them in a situation where their flight attitude causes a crash. Quadrocopters for the most part appeal to a larger group of people who just want to fly something by radio control and don’t necessarily care for a "real" conventional aircraft feel or look or perhaps just want one of the coolest flying gadgets around.

The AR Drone was my first introduction to the quadrotor design and for the low cost – it really is an amazing little heli that even boasts real time first person video (FPV) and RF (WiFi) signal strength and battery condition telemetry. I have been having huge amounts of fun with the Parrot AR Drone - click here to see my full review on it.

Aerial Photo & Video?

Ah yes, the real driving force behind the quadrotor design and the perfect job for them. Since these things fly themselves, hover like they are glued in the air with their overall stability & electronics on the advanced ones keeping them absolutely stationary, efficient lift performance, and essentially take very little skill to pilot, they have become one of the most popular vertical lift and flying platforms for dozens of different photo and video applications. Many of these FPV quadrotor RC helis are also called UAV’s (Unmanned Aerial Vehicles).

One of the most common and recognizable high end radio controlled quadracopters is the Draganflyer X4 industrial vertical lift platform. These have been used in surveillance work, search & rescue operations, and law enforcement for example or in much higher demanding image quality aerial photography/video rolls such as professional photography, video brochures, and aerial real estate to name just a few of the applications. Take a look:

Different RC Quadracopters Currently On The Market

With more and more quadrotor RC helis hitting the marketplace, it is really hard to stay current, but here are a few links to companies that manufacture & carry radio controlled quadrotor helicopters from the hobby variety up to more industrial applications.