Riverwood Robots: ROBOTS: A "Hex-a-What”?! Hexacopters! When 4 Rotor Blades Just Aren’t Enough!

21 August 2014

Quadrotor

I was amused when quadrotors (or quadcopters) made a comeback a few years ago. Suddenly, the media seemed to be filled with images of these rather strange looking mini-UAV’s (unmanned aerial vehicles) with four “helicopter-type” blades instead of one.

I said, “made a comeback,” because quadrotors have been around for a long, long time. The reason why they never made it to the “first string” in aircraft design wasn’t their mechanical complexity. Instead, it was the difficulty of piloting these vehicles. Older designs required a pilot to manipulate the blades, either angle or speed, individually. This translated into a lot of distractions which, for the pilot, were a nightmare.

But with the introduction of complex guidance mechanisms and, then, computers to coordinate the rotor angles and speed, the piloting issues vanished. And the quadrotor was back! But why would anyone want four rotors anyway. The simple helicopter only had one, and it does ok. Doesn’t it?

Actually, the familiar helicopter has always had a lot of problems. The “one” bladed helicopter was a derivative developed from early quadrotor designs. And, the helicopter has more than one rotor – there’s that little one on its tail. Small as it is, that little rotor is extremely important because it allows the helicopter to maneuver horizontally. The problem is that, with the reduced number of blades, helicopters are difficult to maneuver and tend to drift too easily.

So, what’s so great about a quadrotor? Two things: (1) stability in the air, and (2) maneuverability – you can safely operate a mini quadrotor indoors! So, with the addition of computers to coordinate the pitch and/or speed of the rotors, you have an ideal UAV.

Still, foolishly, I thought four blades would be enough. But when computers started coordinating the four rotors, someone realized that computers could coordinate almost any number of rotors. So, why not add a few more rotors? After all, too much is never enough.

Hexacopter

And the hexacopters are here!

Hexacopter: Reconnaissance, Surveillance or . . . Amateur Photography?

Concerns have been raised about the use of UAV’s, particularly mini UAV’s, for certain purposes. To use a mini-UAV for reconnaissance in a combat situation is one thing, but use by law enforcement or even private security firms for surveillance purposes could, in some contexts, be a real danger to individual privacy rights.

But as the debates rage, many other uses for mini-UAV’s seem to popping up. Among others, photographers were delighted with the possibilities offered by the quadrotors. The applications are almost limitless. Consider nature photography, as one example. With a relatively silent approach from above, you may observe and photograph wildlife at distances that would never be possible on foot. And, from the air, you can capture angles that also would be impossible -- without an aerial vehicle. Photography of many difficult to access locations with picturesque geographical features have become, not only possible to photograph, but easy with a quadrotor.

Of course, if you’re familiar with photography, you know that stability is extremely important to good photos. In other words, the camera has to stay still when snapping the picture. Some of the steady camera issues can be compensated for with high shutter speeds that catch images so quickly that the camera has less time to move.

But is a quadrotor stable enough to allow clear photography? Well, sometimes, yes, and, sometimes, no. No aerial vehicle can be perfectly stable under all conditions, but the quadrotor does an amazing job. Again, a mini-UAV version of a quadrotor can be so precisely controlled that it can be flown in-doors without breaking anything.

Stability and precision are the quadrotor’s strengths. So, when the quadrotor is used, it yields good photographic results more often than not. But what if it could be made even better?

Yes, better. A more stable vehicle, in the air, would yield an even greater percentage of good photographs. But what could make a mini-UAV more stable?

More rotors.

Enter the hexacopter. More stable in the air than its ancestor the quadrotor, the hexacopter can produce more high quality photos.

Hexacopter for Professional Aerial Filming

And even greater stability is a real boost for another new group of mini-UAV users – filmmakers. Mini-UAV’s offer an inexpensive and, even, easy way for filmmakers to get aerial camera angles without building expensive scaffolding or loading cameramen and equipment onto even more expensive cranes to be lifted into elevated positions to capture aerial angle shots.

When you need to capture motion, stability becomes even more important and, again, the hexacopter becomes not just a welcome, but valued, addition to the family of mini-UAV’s.

Hexacopter: A Political Leveler?

But there is still a lot of controversy and debate about the possible misuse of mini-UAV’s in government and industry with resulting violations of individual privacy rights. But, at least, one seller sees the hexacopter mini-UAV as a great “leveler.” In other words, besieged with potential privacy violations by government and commercial enterprises, now, a private person can afford their own small fleet of mini-UAV’s. With these, the citizen may be able to better “watch the watchers” -- so to speak.

The Hexacopter and Flower Power

But I know every reader is asking a key question: Sure, you can use a hexacopter for reconnaissance and surveillance . . . and . . . for photography . . . and . . . in the dramatic arts like film production, but . . . where’s the romance?

At least one manufacturer, India’s OM UAV Systems, markets their “Pushpak hexacopter” for more than aerial photography. Their list of “Civilian applications” include “Flower dropping.” What is “flower dropping?”

OM Pushpak Hexacopter

A group of remote controlled hexcopters carrying a payload of flower petals are carefully maneuvered into position at the special event of your choice. At a selected moment, the hexacopters release flower petals onto the area below. The release is a gradual one with petals falling like snowflakes and continuing over a short but substantial period of time.

The Hexacopter: Absolutely the Last Word in Mult-Rotor UAV’s

And so, six engines have solved all the possible issues that could ever come up with this type of mini UAV. Now, we can rest assured that there would be no reason to add any more rotors to our mini-UAV’s.

But wait. There’s the octocopter. Yes, you guessed it -- eight rotors.