Alternative Energies

Following this year’s Electric Aircraft Symposium in Santa Rosa, California, I tagged along with the founder of Mountain High Oxygen, Patrick McLaughlin, as he drove to the Santa Cruz Mountains above Half Moon Bay-company headquarters for Joby Aviation. McLaughlin wanted to compare notes with Joby’s JoeBen Bevirt on the extremely capable motor controllers he had described at the event. He had tried one of Bevirt’s motors with one of his controllers and found it to be a great combination.

The Joby emblem on the design center window reflects a bucolic setting.

Bevirt’s enterprise is set on rolling hills surrounded by lush meadows and thriving vineyards. His dwelling is a beautiful rambler nestled among sequoias, a design center, electric and machine shops, and vegetable gardens. A simple but stylish cabin served as our guest house.

An Inside Look

The next day, Bevirt entered his barn-like design center wearing a salmon-colored T-shirt that read: “If you’re not living on the edge, you’re taking up too much room.” It’s an apt description of his approach to life: to design and do amazing things.

His knobby-jointed camera tripods (a line of infinitely adjustable camera stands called Gorillapods) and light stands dot the area, and sales of those help fund his forays into futuristic thinking that would make a Franklin or Edison proud. Workbenches are covered with experimental models of energy-gathering kites, model airplane electric motors and controllers, and other radio-control gear.

In Bevirt’s vision of addressing our future energy needs, self-launching wind turbines would twirl about at the end of long tethers and send megawatts of power to substations on the ground. To this end, a collection of broken attempts hangs from the open-beam ceiling, some stretching for yards above the heads of designers and engineers clicking away at computer keyboards. Bevirt explained that the most successful kite, so far, has been a high-aspect-ratio monoplane, pulled into the air by model airplane motors and radio-controlled from the ground. On one section of the ceiling, what look like ball and stick models indicate different design paths on which the group has embarked.

Planned unmanned kite-like vehicles, hundreds of feet across, will take some alternate form of control to keep them in their designated spaces. Not to worry: Joby makes autopilots, micro-miniature units setting parameters in three axes and costing (at this time) no more than $550. Bevirt’s electrical shop is set up with stereo microscopes to help his skilled technicians assemble these mini marvels.

JoeBen Bevirt (left), Patrick McLaughlin and engineer Henry Hallam discuss motor development for wind turbines and for the Monarch.

Motor Power

The kites will mount motor/generators to lift them into the sky and act as generators when they reach stiff and constant winds at altitude. No problem. Joby is working on a series of such motors, which are small at this point, but capable of growth. Recently introduced models will be of interest to homebuilders who want to create their own designs. The smallest, the JM1S, is a little more than 6 inches in diameter and a bit more than 2 inches thick. The 1.8 kilogram (3.96 pound), 12.6 peak, 8.2 continuous kilowatt (16.9/11 horsepower) anodized disk is available now, and others with up to 20.9 kW (28 hp) are under development.

Bevirt discusses ideas with Richard Glassock and another developer.

The JM1S sells for $899 and is recommended for model use, though ultralight pilots could be tempted to try a pair on a vintage Lazair or Hummingbird, or something flashy such as a Cri-Cri. This smallest Joby runs at 6000 rpm constant speed, with 9000 rpm a possible peak, probably requiring a propeller reduction drive for most applications.

The JM2 series of motors will be 200 millimeters (7.87 inches) in diameter, heavier and more powerful, but will provide power at 2500 rpm, allowing direct drive. The JM2S will produce 10.5 constant kW and 15.7 peak, weigh 3.35 kilograms (7.37 pounds) and cost $1099. The JM2 will weigh 4 kilograms (8.8 pounds), put out 14 kW constant and 20.9 kW peak, and cost $1299.

Joby’s lead for motor development, Diederik Marius, has created a series of readily identifiable power units, and the company web site expands on future plans. “The design team is currently building 5 kW motors for small airborne wind system prototypes while simultaneously building 20 to 30 kW motors for future vehicles. These motors will be used to pilot and test 30 and 100 kW systems in the short term. Larger motors are planned for multi-MW commercial systems.”

Putting Those Motors to Work

With the current set of smooth, highly flexible motors available, Bevirt could not avoid creating something for which they would be ideal: a vertical takeoff and landing machine that could whisk its lucky owner from one small patch to another, all autonomously. His Monarch is based on a Windward Performance Sparrowhawk ultralight sailplane, Greg Cole’s 36-foot span marvel that often competes with larger glass soaring machines. The Monarch is being built in the Windward shop in Bend, Oregon, under Cole’s watchful eye. Spread eight Joby motors on neat little pods across the top and bottom of the wings, add a pivot mechanism to allow the wings and propellers to point forward or skyward, and the Joby Monarch begins to take shape.

Imagine striding out to your helipad, signaling for the canopy to rise, stepping over the low cockpit frame, and settling into the remarkably comfortable and roomy seat. Punch in the coordinates for your destination, push a start button, and watch as the canopy seals you into a quiet chamber and the propellers begin spinning in unison. Rising to a selected cruising altitude, the small craft begins to move forward as the wing and motors tilt more and more horizontal. In just seconds, the airplane accelerates to cruising speed, and you can sit back and enjoy the view, possibly while monitoring traffic in your area or listening to MP3 tunes or an audiobook.

A rendering of the Monarch.

A Monarch under construction at Windward Performance’s Bend, Oregon, workshop. Note the fuselage nestingunder the wing.

The Monarch

Specifications for the Monarch indicate a 37-foot wingspan, 22-foot fuselage and 300-pound empty weight. Add a 200-pound pilot and a 220-pound, 17 kilowatt-hour battery pack, and the Monarch has a flying weight of 720 pounds. Using 72 kW to lift itself and 12 kW to propel itself at 100 mph, the Monarch has a 1-hour cruising range.

A pilot’s license may not even be possible for this design, because most of us don’t know anyone other than Howard Hughes or the last guy to fly a B-36 who’s been checked out in a design this complex. Molt Taylor, in an interview several years ago, explained that people have perennially wanted the elusive flying car they could fly away at will. But he cautioned that his AeroCar required a vehicle license, trailer license, driver’s license, pilot’s license, airworthiness certificate-a total of nine licenses or certificates to be legal, something the average citizen might not want to pursue.

Skipping the driving-around part of this dream, we have instead a vertical takeoff and landing (VTOL) machine that jumps into the sky from your back yard, say, and takes you to a spot in the parking lot next to your workplace, and back home again at night. You could forgo the pilot’s license, because the craft would be autonomous.

How will Bevirt’s VTOL be easily manageable for the average Prius prodder? Those inexpensive autopilots mentioned earlier will be a big part of this. Highly accurate motor control will be necessary to keep things on the straight and level, and yaw and pitch modulation will require equal precision. The pilot may make inputs, but these will be constantly evaluated by on-board systems that take the precautionary principle to their digital hearts, negating anything that might cause harm to the pilot or others.

The ceiling of the Joby design center is covered with past experiments.

It Takes a Village

Global Positioning Systems (GPS) and highly accurate mapping will enable the Monarch to avoid controlled or uncontrolled flight into terrain, but other aircraft create a more complex concern.

Part of that will be handled by on-board systems, but that automated acumen will require an equally adept air traffic control system. Everything will have to be brought up to date, meaning that our antiquated ATC protocols will require a thorough overhaul to be able to accommodate these free-flying commuters, who will not be using normal runways, climb or descent corridors, or other currently constrained elements of separation and sequencing. They will increasingly be mixing it up with unmanned aerial vehicles (UAVs) and other free-form fliers. As airlines increasingly turn to weather-based routing for maximum fuel economy, the Monarch and its ilk will be a small part of the overall flow.

Monarch propellers with specially designed airfoil shapes by Greg Cole.

Luckily, others are taking on that aspect of future flight. Richard Glassock of Queensland University of Technology in Australia has been exploring this function for the last several years as part of the Smart Skies program. He dropped in to Bevirt’s mountain hideaway to discuss the problem of keeping each diverse aerial vehicle in its own discrete and safe space. The combination of flight dynamics, automated ATC and navigational assurance will all have to be solved for the Monarch to be a plausible solution for future commuters.

Glassock’s efforts have led to the creation of UAVs and a Cessna 172 that use visual and other electronic clues to avoid collisions and maintain positive separation, even though each individual aircraft may be maneuvering with little or no regard to what else is happening in the surrounding air. As UAVs become a part of law-enforcement activities, expanded military applications, border patrol, and other surveillance and enforcement routines, this will be of growing interest and concern to pilots. His efforts fit neatly into a need that will only grow.

At What Price?

Is this much technology packed into a compact aircraft going to be even remotely affordable? At a presentation in 2009, Bevirt suggested a price of $30,000 or less, a surprising number to pilots who might spend that much for a glass cockpit. Consider, though, that mass production and the already low cost of components could well lead to that kind of number, with the only extra cost being the high price of batteries. Today, the battery packs alone, especially for 100-mile trips on eight small motors, exceed the projected cost of the aircraft. The heartburn this prompts might be alleviated when a user thinks of these energy storage devices as an expensive gas tank, but one for which fuel is remarkably cheap.

Bevirt notes that lithium battery packs “range from $0.30 to $0.60 watt-hour, so a 17kWh pack costs $5000 to $10,000.”

Compare the difference between paying $5 to $6 per gallon for aviation fuel, and the long-term cost of even a $10,000 battery pack for the Monarch. If the pack costs $1 per recharge for an hour’s flight, eventually that initial cost will be reimbursed.

Joby’s motors will be getting a thorough test because McLaughlin loaded four of Bevirt’s best in his station wagon for the trip to his home in Redmond, Oregon, where he will hook them up to his controllers. So far, he has been happily impressed with the operation and flexibility of the combination. At least part of the equation may be solved for Joby’s coming revolution in personal travel.

The infrastructure needed to support this dream may be another matter. As much as possible, initial craft in this line will be self-sufficient (with their own guidance and control systems), require a licensed pilot, and probably special certification and training for first-time buyers. Air traffic control (ATC) systems will need rapid updating, something not likely to be on any bureaucrat’s priority list during these difficult economic times.

The basic design is sound, though, and if batteries come down in price and go up in power-to-weight, a new age of personal aviation could look a lot like Bevirt’s ideas writ large.