Quadcopter Reviews

What is a quadcopter?

While drones can also be planes or helicopters, the most popular personal drone right now is the quadcopter.  Quadcopters are popular due to their small size, precision control, agility, power and stability.  Quadcopter design has become to standard for personal and commercial drones, while the military still seems to favor more traditional plane like designs.

What is a quadcopter?   Let’s take a look.

What is a quadcopter?

Quadcopters are also called multirotors, due to them having 4 or more small rotors instead of one like the traditional helicopter.  Some models have more than 4 rotors and are called multirotors.   As a general rule, the more rotors a drone has, the stronger and more stable it becomes.  This why the more high end professional photography drones have 6 to 8 rotors, but these units are currently thousands of dollars.

Quadcopter History

The quadcopter and multirotor designs have been around for a very long time, but the design is inherently unstable.  With 4 rotors spinning, keep them moving at the right speed to keep the quadcopter level and stable is difficult.

Quadcopter history

Helicopter #2 designed and built by Etienne Oemichen – 1922

In 1922, Etienne Oemichen developed the first quadcopter that was considered a success.  In November of 1922, Etienne first flew Oehmichen #2 (pictured above).  #2 was an improved helicopter featuring vertically mounted rotors which rotated in the opposite direction from the large top rotors.  Most experts agree that Oemichen created the very first reliable helicopter capable of carrying a person.

Oemichen’s quadcopter design had influence into a significant design break through in make quadcopters a viable flight machine.  The design had two propellers spin in one direction and two spin in the opposite direction.  This increased stability and enabled the quadcopter to fly successfully.   Quadcopters today still use this same basic design.

Even with opposite rotating rotors, quadcopters without today’s technology were still unstable compared to alternatives and required very skilled pilots to successfully fly them.

Modern day quadcopters

The quadcopter design never really caught on in mainstream aircraft design due to the stability issues; however, quadcopters have recently become very popular with radio controlled (RC) aircraft, and in particular drones.

Recent advances in technology have addressed issues that plagued early quadcopter design, including poor stability, limited control and complexity.  Modern quadcopters are very stable, easy to control and easy to fly.  This includes both large models and many small models.  As an example, the under $50 Hubsan X4 or the Syma X1 are incredibly easy to fly and very stable.   Both are frankly pretty amazing and great examples of how far the technology has come.

Quadcopter Technology

Quadcopters are stabilized with a number of technologies, but the primary one is the gyroscope.  There are currently two types of gyroscopes:

  • 3 Axis
  • 6 Axis

3 axis gyroscopes auto-balance the pitch  (forward and aft tilt) and the roll (right and left tilt).  A quadcopter that is set-up correctly, will hover without moving in mid-air when the transmitter control sticks are centered.  While hovering, the quadcopter should remain in place, and not “drift” in one direction or the other.  This drifting is technically called “attitude displacement”, and also occurs when the pilot moves the stick.  Correction of attitude displacement, using the 3 Axis design, causes the unit to return to a hiving position when the pilot returns the controls to the “center” position.

Quadcopter pitch roll yaw

6 axis gyroscope stabilization adds 3 accelerometers which sense acceleration in 3 directions.   The combination of the 3 axis gyroscope and accelerometers provides much quicker response to attitude displacement.    The big advantage to 6 axis stabilization is that the quadcopter can automatically adjust to wind gusts and even stabilize itself after bumping up against something.

The really great thing?  6-axis stabilization is so inexpensive due to recent technology and manufacturing advances, that it’s found in many commercially available quadcopters, even the inexpensive Hubsan X4.

The video below shows you just how stable and agile modern day quadcopters are.  The video was shot with a DJI Phantom 2 – just amazing.  You can read more about aerial photography here.

Interested in purchasing a quadcopter? make sure you review our article on best quadcopters so you can find the right one for your needs and within your budget.  You can also see a full list of current commercial drone models for sale.

Photo by: Kevin Baird

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