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FireFLY6: A Different Kind of RC Multi-Rotor

By Terry Dunn

With the exploding popularity of multi-rotor RC aircraft, the market is becoming flooded with models in all sizes and rotor counts. An upstart company in New Hampshire has created a hybrid multi-rotor design that separates itself from the herd.

With the exploding popularity of multi-rotor RC aircraft, the market is becoming flooded with models in all sizes and rotor counts. While there are definite variations in quality and performance, nearly all of these models are constrained by the limitations of a pure multi-rotor platform. An upstart company in New Hampshire has created a hybrid multi-rotor design that separates itself from the herd. Its creators believe that this machine retains all of the things that we love about multi-rotors, while adding some useful new capabilities.

The aircraft of note is the FireFLY6 from BirdsEyeView Aerobotics. It is a Y-configuration tri-rotor that has some very unique attributes. The machine’s most obvious feature is its wing--a moot appendage on standard multi-rotors. On the FireFLY6, however, the forward two rotors can tilt 90-degrees to transition the ship from a hovering tri-rotor to a forward flying airplane (where the wing proves quite useful). To equate this capability in full-scale aircraft terms, think Harrier Jump Jet or V-22 Osprey.

What's the Benefit?

Despite their beloved camera-toting abilities, most multi-rotors are only capable of rather pedestrian forward speeds. Flyers that want to cover a lot of ground with each flight are typically forced to abandon the rotors and adopt conventional fixed-wing models. By doing so, they forfeit the ability to hover and operate from confined spaces. These are the same constraints that spurred development of the Harrier and Osprey: the need to take off and land with little (or no) runway and then get where you’re going in a hurry.

BirdsEyeView’s founder Adam Sloan notes that “I’ve long believed that the ultimate flying robot is one that can take off and land vertically, but also transition to efficient forward flight.” As off-the-shelf multi-rotor electronics matured to the point that hands-off hovering was feasible, Sloan began piecing together the elements of his dream machine. By February of 2012 his prototype aircraft was able to execute in-flight transitions from hovering to forward flight.

The FireFLY6 is a morph of a tri-rotor and a flying wing. The idea is to be able to take off and land without a runway and still be able to fly somewhere quickly.

As you might expect, it is the transition phase that has given Sloan’s team the most grief. He explains, “We had to learn the best techniques for piloting into and out of hover situations through trial and error. Learning how to do so reliably (both in terms of materials used and method of piloting), and getting that dialed-in to the point where it is now, was probably the biggest development hurdle.”

Aside from the potential performance benefits of an airplane/multi-rotor hybrid, Sloan points out that there are longevity perks as well. He notes, “I think those who are familiar with foamies (model aircraft constructed of foam) will find themselves doing a lot less repair work. Vertical takeoff and landing is a much less violent process than your average foamie skid landing (sliding on the ground without landing gear).”

But as with any “Jack of all trades” endeavor, you have to have to make some sacrifices.

In the case of the FireFLY6, it seems that the majority of those sacrifices are related to mass. When in tri-rotor mode, you are stuck schlepping around airplane-specific parts rather than useful payload (or less payload). The opposite is true when in forward flight. The question to be answered is whether this design manages to keep the best of both worlds while forfeiting things that we can live without. Some morphs are able to transcend the “master of none” outcome and actually become more useful than the sum of their parts. The camera phone is a shining success story. We can debate the spork another time.

The fact that similar flying machine hybrids have already been vetted in the full-scale world bodes well for the FireFLY6. If nothing else, the Harrier and Osprey (and to some degree the F-35B) prove that hovering fast-movers can be practical and useful. I suppose it’s all in the execution, which took quite some time for the V-22. If this stuff was easy, we’d all be driving flying cars by now.

Who is the FireFLY6 For?

Sloan cut his teeth in the miniature aircraft world while designing fixed-wing Unmanned Aerial Systems (UAS) for the US military. He left the UAS industry for a bit, but returned after the FAA Modernization and Reform Act of 2012 was passed by Congress. A key part of this legislation is a requirement for the FAA to recognize and manage UAS as legitimate users of our airspace. This was the catalyst that Sloan needed to create BirdsEyeView Aerobotics. Of particular interest to him and other UAS entrepreneurs was the emphasis placed on defining the rules for small, commercial UAS early in the process. This would clear the way for introducing the FireFLY6 into a market eager to explore the non-military potential of UAS platforms.

Many RC flyers will be attracted to the FireFLY6 purely for its ability to hover and transition to forward flight.

The FAA act is now more than two years old and we still don’t have direction regarding commercial UAS activities. The delay, however, does not affect BirdsEyeView’s business plan. All along, their intent has been to start out by providing their product to hobbyists. They see the genesis of the technology unfolding much like PCs and cell phones, in that private users will lay the groundwork and develop the “killer-apps” that are eventually adopted by businesses.

(You may have noticed that I haven’t called the FireFLY6 a drone, which is out of respect for BirdsEyeView’s aversion to the word. They feel that “drone” suggests a machine with more militant and perhaps nefarious ambitions. The team would rather you call the FireFLY6 an aerobot – a self-coined term defined as “a flying robot for everyday people.”)

Many RC flyers will be attracted to the FireFLY6 purely for its ability to hover and transition to forward flight. That capability is very unique and would certainly impress your buddies at the flying field. Another group that will likely take a shine to the FireFLY6 is aerial photographers, to include most multi-rotor flyers. Within the aerial photography realm is a subset of modelers who do First Person View (FPV) flying. These are the guys who fly while wearing goggles that display what the onboard camera sees. With places to mount 2 cameras, it is easy to understand why photographers and FPV flyers would take notice of this ship.

In addition to a belly camera mount, an interchangeable nose section can fit a second GoPro for a clear forward view.

The airframe has a built-in GoPro mount in the belly. The mount is angled to face forward and downward, providing landscape views while in flight. There is also an additional mount to place a second GoPro in the nose. This location gives an unobstructed forward view. The design does not currently incorporate a gimbal on either mount. Sloan mentioned that his team is presently experimenting with a small gimbal system. He adds that that the foam airframe permits easy modifications for anyone who wants to try their own gimbal hack.

How Does it Work?

Although the FireFLY6 is technically a tri-rotor, it has six motors arranged in three coaxial pairs. The motors in each pair spin in opposite directions to neutralize torque effects. As mentioned previously, the forward two rotors are mounted on a common beam than can be rotated to alter the direction of thrust from the four motors. The beefy-looking rotation mechanism appears as if it was borrowed from a BMX bicycle…stout stuff.

Three pairs of brushless motors power the FireFLY6. Notice that the propellers turn in opposite directions to negate torque effects. The components zip-tied to the beam are electronic speed controls.

The control requirements for a multi-rotor differ significantly from those for an airplane. Multi-rotors utilize a control board that manages the speed of every motor to accomplish all aspects of flight. With an airplane, the motors only provide forward thrust while aerodynamic control surfaces handle directional control. To integrate these two systems, BirdsEyeView created a device called the Bridge. The Bridge also allows the use of a separate stabilization system for forward flight. A unique aspect of the Bridge is that it was designed to allow the user to implement any brand of multi-rotor control board and forward flight stabilizer that they choose.

To merge the electronic components required for multi-rotor or aircraft operations, the BirdsEyeView Aerobotics team designed the Bridge. It interfaces with both sets of components and allows mode changes during flight.
On a typical flight, the user will take off vertically in tri-rotor mode and retract the wheeled landing gear. They can then convert to airplane mode and fly at much higher forward speed.

On a typical flight, the user will take off vertically in tri-rotor mode and retract the wheeled landing gear. They can then convert to airplane mode and see the sights (or check the crops, or inspect the pipeline, etc.) at a much higher forward speed. If anything piqued their interest during the flight, they could flip back to tri-rotor mode and take a closer, hovering look. When it’s time to land, they will come in vertically as a tri-rotor. Airplane-style takeoffs and landings are possible as well. But, I suspect you only do those when there no one around to impress with your gnarly transition skills!

The FireFLY6 is not for beginning modelers. It is intended for pilots who are already comfortable with both multi-rotors and conventional airplanes. They must be ready to make the mental leap of piloting one type of aircraft to the other on-the-fly…so to speak. While the FireFly6 does not really require any construction, owners will need to do a little bit of soldering as well as setup of the radio system and control board.

When Can I Get One?

For those of you chomping at the bit to try this thing out, BirdsEyeView expects to begin shipping FireFLY6 production units in mid-July of this year. They are currently accepting pre-orders on their website. With an ever-growing array of cookie cutter multi-rotors filling store shelves, it will be exciting to see this new concept hit the stage and observe how it might reshape our expectations of RC flight.

All photos courtesy of BirdsEyeView Aerobotics