Technicalities: Making Aviation Sustainable

Electric airplanes, like the eVTOL Cora, can use renewable energy.
Electric airplanes, like the eVTOL Cora, can use renewable energy. (Courtesy Wisk/)

JetBlue announced in January that it intended to become a carbon-neutral airline. To reduce its net carbon footprint, it would begin purchasing carbon offsets—credits generated by sponsoring activities and investments designed to reduce carbon-dioxide emissions. Its flights originating in San Francisco would use a low-emissions substitute for jet-A refined from a mess of pottage that includes used cooking oil, animal and fish fat, tall-oil pitch (a byproduct of pulping wood), and—get ready—“spent bleaching earth oil.”

The announcement was not shocking. Other airlines, and the US Air Force, are already using several million gallons of biomass fuel a year on an experimental basis, and way back in 2008, Virgin Atlantic staged a publicity event in which one of its Boeing 747s flew on such a brew, blended—as experimental fuels usually are—with a good deal of the real thing.

So, you might have expected little hostile reaction to the new policy, which the airline promised would have no effect on safety or ticket prices and was probably just intended to enhance its cred with environmentally concerned customers. Nevertheless, it ignited the highly combustible fury of commenters on a Fox News site. Sustainability in aviation, it seems, is more of a political matter than a technological one. Sustainability is connected with resource depletion and climate change, and for many people and corporations, both are hoaxes inimical to commerce and profits.

While we argue, however, energy pours down from the sun. Finding ways to capture it and convert it to usable forms is what sustainability means, and I don’t see why this should be controversial.

Two-thirds of US oil consumption takes place in pursuit of transportation. Jet fuel represents about a tenth of that; aviation turbines consumed about 100 billion gallons of fuel in 2018. Less than two percent of aviation fuel consists of the boutique cocktail known as avgas, and so practically all discussion of sustainable fuels for aviation focuses on renewable replacements for jet fuel.

Fortunately, turbine engines are not so finicky as recips, and the magic of industrial chemistry can turn all sorts of energy-containing stuff into liquids of tolerably digestible viscosity and volatility. There are collateral issues, however—land and water use, environmental impacts, cost, and (in the case of corn) diversion of a needed foodstuff from human and animal consumers—so the best avenue to a sustainable fuel remains uncertain.

Plants convert sunlight into organic-chemical structures that can in turn be transformed into so-called biomass liquid fuels. The process is inefficient and requires large amounts of arable land. Current feedstocks such as corn, sugar cane and switch grass yield only 400 to 1,100 gallons of fuel per acre and consume vast amounts of water; at one point, corn grown for ethanol in Nebraska was slurping up 780 gallons of water per gallon of fuel produced. Ethanol, currently the most commonly used biofuel, is already blended into most road-vehicle gas sold in the US. Ethanol can also be blended with jet fuel, but it has only two-thirds the energy content of petroleum-derived fuels, so you have to carry more of it for a given trip.

Bacteria, in the form of algae, yield five times more energy per acre than plants, and even higher yields are theoretically possible. Unlike plant feedstocks, they produce fuels similar in energy density to petroleum. They are also easy targets for genetic manipulation; maybe some 17-year-old with a Crispr genome-editing kit will figure out how to make them ooze flight-ready jet-A. But bacteria are fussier about their living conditions than switchgrass, and their exploitation on an industrial scale is distant.

The piston-engine situation is less hopeful. Even the relatively modest project of developing a lead-free 100LL replacement has stumbled. High-octane gasoline works in medium-performance engines, but it is not a renewable fuel; and a leadless 100-octane fuel for high-compression or turbocharged engines, fungible with avgas, has proved elusive.

This is where electricity comes in, with a brave flourish of trumpets.

Set electric airliners aside. Even if battery energy density doubled or quadrupled, it would still fall far short of that of the liquid fuels on which the entire structure of long-range air transportation is based. The most likely route to sustainability and emissions reduction for medium- and long-range jet airplanes is a new fuel, not the creation of a completely new flight technology.

Read More from Peter Garrison: Technicalities

Nevertheless, hundreds of startups are feverishly pursuing electric propulsion. Most will fail for the usual reasons: lack of financing or lack of talent—or both. Some airplanes suitable for carrying small loads on short routes will be created; speed, which is a great devourer of energy, is less important on short routes.

Electric power is particularly appropriate for the new paradigm represented by the autonomous VTOL multicopter, whose fixed-pitch (therefore, simple and cheap) fans respond rapidly to changes in power and make self-stabilization possible. A much-simpler and more-modest

application is already here: the small electric trainer or sport aircraft rechargeable from an electric outlet or, in a slightly more utopian vision, by a patch of solar cells on the airport.

Hybrid-electric power systems are getting a lot of study, even by the likes of Boeing and Airbus. They consist of one or more electric motors driving propellers or fans, a sustainer engine, and a battery whose size, and share of the work, is optional. The sustainer engine—diesel, turbine, turbo-compound rotary or whatever else you may have handy—is sized for cruise and optimized for economical operation in a narrow band. It runs on a sustainable fuel. It drives a generator to produce voltage, which in turn drives the electric motor. For takeoff and climb, and possibly for short cruise segments, the battery contributes extra power.

Hybrid systems are compromises. There are significant inefficiencies between their stages. The supreme mechanical simplicity of the battery- driven electric motor is sacrificed. Whether the versatility and small size of electric motors lead to compensating aerodynamic advantages, for instance from distributed or vectored thrust, is now being studied.

For small, medium-range airplanes, a possible alternative to the complexity of a hybrid powertrain is the fuel cell, which is a kind of battery that is continuously recharged by a chemical fuel. The fuel of choice is hydrogen. Hydrogen is three times as potent, per pound, as gasoline, and it’s clean; the main exhaust product of a hydrogen fuel cell is water. So far, so good. But unfortunately, hydrogen is a very light gas. Even compressed to 10,000 psi, it is less compact, as an energy reservoir, than gasoline. This is not an insuperable problem for road vehicles—several models of hydrogen-fuel-cell cars and buses are on the market—but it’s inconvenient for airplanes. Still, cylindrical high-pressure tanks could be integrated into airframes, some perhaps doubling as spars, and certain nanomaterials may be found to soak up and hold hydrogen like sponges.

Aviation technology has remained essentially static—or, at best, very slow-moving—since the jet engine came into use in middle of the past century. Fresh attention to new fuels, including electricity, and new configurations for using them, opens the door to interesting and exciting innovations. They will be decades in development, but we ought to welcome them, regardless of our politics.


This story appeared in the April 2020 issue of Flying Magazine

Cessna SkyCourier Successfully Completes First Flight

The SkyCourier can be ordered as a freight or passenger aircraft or a combination of both.
The SkyCourier can be ordered as a freight or passenger aircraft or a combination of both. (Textron Aviation/)

Cessna Aircraft’s SkyCourier, the company’s first new twin turboprop aircraft in a generation, took to the skies over Wichita, Kansas, on Sunday, May 17, for its first flight—a significant step toward entry into service for the clean-sheet aircraft.

The SkyCourier departed the company’s Beech Field Airport (KBEC) east campus, with Corey Eckhart, senior test pilot at the controls assisted by Aaron Tobias, Cessna’s chief test pilot. During the 2-hour and 15-minute flight, the team tested the aircraft’s performance, stability and control and its propulsion, environmental, flight controls and avionics systems. This first flight kicks off the important flight test program that validates the SkyCourier’s performance. The prototype aircraft, along with five additional flight and ground test articles, will continue to expand on performance goals, focusing on testing flight controls and aerodynamics.

The Cessna 408 SkyCourier will be offered in various configurations including a 6,000-pound payload capable freighter, a 19-seat passenger version or a mixed passenger/freight combination, all based on the common platform. The new high-utilization turboprop is powered by a pair of Pratt & Whitney Canada PT6A-65SC engines. The cockpit includes a Garmin G1000 NXi avionics suite. The SkyCourier promises a maximum cruise speed of up to 200 ktas and a maximum range of 900 nm. Both freighter and passenger variants of the airplane will include single-point pressure refueling as standard.

US Air Force Orders New F-15EXs

The F-15EX is a much-updated version of the original airplane that first flew in 1972.
The F-15EX is a much-updated version of the original airplane that first flew in 1972. (Boeing/)

The first McDonnell F-15 fighter jet flew back in July 1972, and yet Boeing reported last week that the US Air Force just ordered eight of the airplanes valued at just over $1.1 billion. The reasoning behind why the Air Force would buy a 50-year-old airplane made more sense once Boeing announced the airplanes were actually the newest version of the company’s fourth-generation plus F-15EX fighters. The Chicago-based aircraft builder said the Air Force plans to purchase as many as 144 of the F-15EX airplanes in the future.

The F-15 has always been a spectacular performer, according to Boeing. According to a story published by Air Force magazine, the new EX will include a “substantially more powerful mission computer, new cockpit displays, a digital backbone, and the Eagle Passive Active Warning Survivability System (EPAWSS)—an electronic warfare and threat identification system.”

In addition to the F-15s well-known and impressive flying characteristics, the F-15EX is capable of carrying an external payload of up to 22 AIM-9X Sidewinder and AMRAAM medium range air-to-air missiles. Though the most modern US fighter—the F-35—was developed as a stealth aircraft, it is only capable of carrying four AMRAAMs within its weapons bay in order to maintain its stealth capability.

Highlighting the spectacular performance of even the original F-15, Boeing said in a company history, “In early 1975, flying out of Grand Forks Air Force Base in North Dakota, an F-15A known as Streak Eagle set many time-to-climb world records. Between January 16 and February 1, 1975, the Streak Eagle broke eight time-to-climb world records. It reached an altitude of 98,425 feet just 3 minutes, 27.8 seconds from brake release at takeoff and coasted to nearly 103,000 feet before descending.”

Bearhawk Aircraft Details a Pair of Company Firsts

This Bearhawk won the STOL contest in New Zealand in February.
This Bearhawk won the STOL contest in New Zealand in February. (Bearhawk Aircraft/)

Austin, Texas-based Bearhawk Aircraft, a company known for creating STOL kit airplanes, earlier this week announced two company milestones. In one, a Bearhawk Patrol became the first of the company’s airplanes completed in Brazil to take flight, launching from Lontras, Santa Catarina, Brazil. In another, a New Zealand man for the second time took top honors in an annual STOL contest flying a Bearhawk.

In a news release, Bearhawk said the first Brazilian airplane was a “quick-build kit purchased during EAA AirVenture 2014 by Fernando Frahm who, along with his son Andre and co-owner/builder Roberto Lindner, completed the airplane in January 2020. Roberto said the ‘Patrol exhibited takeoff and climb performance he’d never before experienced in any aircraft of its class.’”

As a rancher in southern Brazil, Fernando said he knew immediately following a demo flight at AirVenture that the Bearhawk was the aircraft for him. In addition to the airplane’s STOL capabilities, Fernando said the Patrol delivered greater travel flexibility at better cruise speeds than similar STOL/utility aircraft he had been considering. The basic Bearhawk Patrol configuration includes a Superior IO-360 180-horsepower engine with a Dual Plasma II Ignition system from Light Speed and a constant speed propeller from MT-Propeller of Germany. A company produced video captured some of the Patrol’s performance capabilities.

At Omaka Airfield, Blenheim, New Zealand, Jonathan Battson took top honors in his Bearhawk for the second year in a row winning the Healthy Bastards Bush Pilot Championships held on February 1, 2020. Battson won with a total combined takeoff and landing distance of 233 feet compared to 354 feet and 430 feet for second and third place. Battson said a number of people who normally attend the famous Valdez STOL contest came to New Zealand and found “the flying was as good [at Omaka] as they see in Valdez… except here the action is faster and the crowd is much closer to the action.”

The Next Gulfstream G700s Enter Flight Test

The next flight-test aircraft have joined the G700 program fleet.
The next flight-test aircraft have joined the G700 program fleet. ( Gulfstream Aerospace/)

One encouraging sign during the collective slowdown of the aviation industry in the second quarter of 2020: OEMs continue aircraft development programs—and that includes Gulfstream’s pursuit of the G700 certification. The company announced in early May that the second and third aircraft within the G700 program are now undergoing flight test. The second test platform flew on March 20, and the third took its first flight from Savannah, Georgia, on May 8.

The second test aircraft, on the March 20 flight, departed Savannah/Hilton Head International Airport and spent 2 hours and 58 minutes airborne, reaching an altitude of 45,000 ft msl and a speed of Mach 0.85. On May 8, the third test aircraft left KSAV and flew for 3 hours, 2 minutes, achieving the same altitude and speed marks as its sister ship.

The three flight-test aircraft have flown more than 100 hours since the program’s first flight on February 14. Overall, the G700 has reached a maximum altitude of 54,000 ft and a maximum speed of Mach 0.94. The current flight-test fleet is used for envelope expansion, flutter testing, flying qualities and flight control, as well as mechanical systems, flights into known icing and environmental control systems.

Gulfstream also announced it had received EASA type certification on the G600 on May 11, enabling deliveries to begin for its European customers.

Daher Updates on HomeSafe Autoland for the TBM 940

Most all of the elements required for the activation of HomeSafe are already found on 2019 and 2020 TBM 940 models.
Most all of the elements required for the activation of HomeSafe are already found on 2019 and 2020 TBM 940 models. (Daher/Airborne Films/)

Daher gave an update on the HomeSafe autoland capability for the TBM 940 in a media briefing on Wednesday, May 6. Senior vice president of Daher’s Aircraft Division, Nicolas Chabbert, announced that Garmin’s emergency Autoland capability—standard on all 2020 940 models—would be available once final certification testing was complete. Phil Straub, executive vice president for Garmin Aviation, gave specifics on the challenges faced in making the final yards to the finish line—particularly the detailed coordination with air traffic control and its representative constituents within the federal government. Still, Straub expressed confidence that the final certification would be complete this summer.

HomeSafe can be retrofit to all 2019 and 2020 TBM 940 models already delivered once the software completes final EASA certification, which for the TBM 940 is expected at the end of June or early July this summer. Chabbert said that FAA certification would follow thereafter. There are two separate retrofit pathways for the 2019 versus the 2020 models, as more would need to be completed on the 2019 aircraft to activate the HomeSafe functionality. The retrofit pricing for 2019 940 models—once the final approval is made—was given as $85,000, while the retrofit on 2020 was included in the purchase price.

Key for Daher was the development of the passenger-centric HomeSafe’s user interface—to keep the underlying complexity as simple as possible. This way, use of the system doesn’t require passenger training—just passenger briefing, Chabbert stressed. The activation button itself is purposefully placed outside of the instrument panel’s main topography for this reason—because “that’s the pilot’s area,” he said. This way, the passenger can press the button without any “fear” that they are crossing into that territory.

From a company-wide standpoint, Daher and Kodiak have followed a progressive update program to modify production to meet the new standards made necessary by the novel coronavirus outbreak. The first of the TBM 940 aircraft produced under the new “COVID-19” manufacturing protocols, serial number 1321, had made it way to the US and was crossing the Midwest at the time of the press briefing. According to Chabbert, the company expects to deliver “9 or 10 aircraft” before the end of the second quarter.

Overall, both Chabbert and David Schuck, director of Kodiak Care for the company, expressed optimism in the amount of activity registered both by the TBM fleet and the service centers in spite of the global downturn. Chabbert noted that the TBM fleet registered about a 50-percent decrease in activity in April 2020 as compared to the year prior—but that owners were still clearly using their aircraft as an alternative to the airlines. He foresees this will continue. “Aviation is going to be different,” he said. “And HomeSafe is a part of this.”

Schuck indicated that the service side of the business has seen an uptick since the stay-at-home orders began in the US. Customers are taking the downtime to complete deferred maintenance and retrofits. He also expects to see greater utilization of general aviation in the months and years to come. “I believe our customers and owners will prefer to use their aircraft rather than the airlines,” he said, because doing so gives them control over whom they fly with, and when the aircraft gets cleaned and serviced.

The combined fleet has stayed active in the efforts to confront the outbreak, with a couple of key missions outlining the utility of the aircraft. The Kodiak was used to deliver a total of 240 ventilators from a manufacturer—conveniently located in Sandpoint, Idaho, near the Kodiak facility—to medical teams in Sacramento, California, where they were needed. Similar relief flights, transporting medical personnel, have used TBMs to bring folks from southern parts of France to the Paris area to support efforts there.

The TBM 940 has a maximum range of 1,730 nm and a top cruise speed of 330 knots. Maximum payload is 1,400 pounds, and minimum field length for takeoff is 2,380 feet. The 940 joins two other airplanes awaiting Autoland certification: the Piper M600 Halo, and the Cirrus Vision Jet with SafeReturn.

Approachable Aircraft: The Cessna 120/140

The 120 and 140 were some of the most successful ­postwar light aircraft in the US.
The 120 and 140 were some of the most successful ­postwar light aircraft in the US. (Jason McDowell/)

It is often said that a first-time airplane buyer should buy his or her last airplane first. The reasoning is, it makes little sense to invest in an airplane the pilot will outgrow or become bored with. A more expensive option may, in fact, prove to be a better long-term value by serving as a more permanent solution to the pilot’s needs.

Still, a budget is a budget, and while mission requirements vary considerably from one pilot to another, one common goal is to find an airplane that remains interesting and fun while minimizing the cost of ownership. In this respect, the Cessna 120 and 140 offer an intriguing blend of qualities for the new pilot and/or first-time buyer.

Model History

The 120 and 140 were some of the most successful postwar light aircraft in the US. Nearly 8,000 were built between 1946 and 1951, and more than 2,500 remain on the FAA register today.

The 120 was developed as a budget version of the 140, initially lacking flaps, rear side windows and electrical systems. Over the past 70-plus years, however, most of the 120 fleet has been modified with electrical systems and other upgrades.

Today, the presence of flaps is the primary difference between the two models, and with many 140 owners reporting little difference in performance with flaps down, the 120’s lack of flaps should not be considered a significant disadvantage.

The most desirable variant of the family is the 140A. Introduced in 1949, it offered a metal wing with more effective flaps and a redesigned instrument panel. The 140A was also available as the Patroller model, which included Plexiglas doors, a message chute, and a whopping 42-gallon fuel capacity that provided an endurance of around seven hours.

Park a 140 on a ramp, And you’ll soon be making new friends as they meander over to swap stories.
Park a 140 on a ramp, And you’ll soon be making new friends as they meander over to swap stories. ( Dustin Mosher/)

Current Market

As of early 2020, there were 14 140s and two 120s listed for sale in various places, with a median price of $25,000. The most and least expensive examples were significant outliers at $40,000 and $16,000, respectively.

While all the typical factors such as airframe time, engine time since major overhaul and general condition affect these prices, two particular items affect the 120 and 140 more than many other aircraft types—fabric condition and engine type.

Excluding the aforementioned 140A with its standard metal wing—and other 120s and 140s that have had their fabric wings converted to metal at some point in their lives—most 120s and 140s are equipped with fabric wings. While good, modern fabric can last for several decades when properly cared for, it’s wise to determine the age and condition of the fabric as part of a pre-purchase inspection.

With owners reporting $8,000 to $10,000 costs to replace the fabric and address minor internal repairs that are commonly found during the process, fabric replacement can approach half the total value of many airplanes on the market. Accordingly, purchasing an airplane with old, deteriorating fabric is not unlike purchasing an airplane with an engine in need of overhaul, and the selling price should be adjusted appropriately.

Jeff Tourt’s Cessna 140 panel basks in the sun.
Jeff Tourt’s Cessna 140 panel basks in the sun. (Courtesy Jeff Tourt/)

There are multiple engine types found in the Cessna 120/140 fleets. The most common—and, typically, the least expensive—is the 85 hp Continental C85 that came equipped in most examples. The noticeably more powerful C90 is less common but very well-liked for its blend of low weight and higher power.

A popular upgrade is the ubiquitous 100 hp Continental O-200, but because the rated horsepower is only attainable at higher rpm, many owners prefer instead to upgrade their C85s with an O-200 crankshaft as an STC. This provides additional power at a lower, more usable rpm range than the O-200.

Finally, some examples are fitted with the more powerful 108 hp Lycoming O-235 and 125 to 135 hp O-290. While the additional power makes a 120 or 140 perform notably better on climbout, these engines are also heavier, and payload can suffer. Additionally, because the O-290 is no longer produced or supported, parts have become both difficult to find and significantly more expensive than the alternatives.

Current FAA records indicate 674 120s, 1,653 140s and 235 140As are on the registry. The relative rarity of the 140A combined with its more sought-after features commands a premium over the others, with prices that are commonly 20 to 30 percent higher than the rest.

Ultimately, the most desirable examples have a recently overhauled engine, newer wing fabric, a well-kept interior and a reasonably up-to-date, ADS-B-compliant panel.

Randy Thompson’s ­royal blue 140 panel.
Randy Thompson’s ­royal blue 140 panel. (Courtesy Randy Thompson/)

Flying Characteristics

Because the 120 and 140 are essentially tailwheel predecessors of the first 150s, the flight qualities are very similar. Unfortunately, so is the limited useful load. The maximum gross weight for the 120 and 140 is 1,450 pounds, and 1,500 pounds for the 140A. All have a standard fuel capacity of 25 gallons and empty weights that range from 800 to 1,050 pounds, resulting in a rather-limited payload.

With a heavier O-290 bringing his airplane’s empty weight up to 1,050 pounds, one owner reports having only 250 pounds left over for people and bags, underscoring the concern about the heavier, more powerful engine options. Similarly, most pilots prefer the fabric wing because it tends to weigh 30 to 50 pounds less than those that have been metalized.

The tailwheel configuration is, of course, what makes the 120 and 140 so vastly different from the 150. And the relatively benign handling and ground manners make it a great introduction to tailwheel flying. Visibility over the nose is fantastic, and the effective rudder makes takeoffs straightforward.

Once in the air, the 120 and 140 do indeed feel akin to the 150, providing a typical cruise speed of 100 to 110 mph with similar cabin comfort, space and handling qualities. Fuel burn varies by engine choice, but 4.5 to 5 gallons per hour is common. The fabric wing provides nice flying characteristics, with a light, crisp roll and an exceptionally docile and predictable stall.

Full-stall, three-point landings are almost a nonevent in the 120 and 140. By the time you milk every last bit of lift out of the wing and settle onto the runway, the remaining speed and energy is so low, very little effort is required to manage the otherwise typical tailwheel characteristics as you roll to a stop.

Wheel landings require more attention, particularly on lumpy grass strips. While most bounces on landing tend to be the result of a misjudged flare or an effort to force the airplane onto the runway, the Cessna’s undamped spring-steel landing gear is quick to convert an errant runway lump into an unplanned trip back into the air.

Ray Huckleberry’s 140 before restoration.
Ray Huckleberry’s 140 before restoration. (Courtesy Ray Huckleberry/)

Early on, the 120 and 140 earned a reputation of being prone to nosing over while braking. Though many blame this on the positioning of the landing gear, the belief was more likely a result of brakes that were unusually powerful for the time period.

In that era, other light-tailwheel-aircraft types typically came equipped with relatively weak, cable-actuated brakes activated by tiny heel pedals. The 120 and 140, on the other hand, came with much more effective hydraulic toe brakes. This resulting combination of leverage and power ended in nose-over accidents when unsuspecting pilots jammed on the brakes.

To address this, many 120s and 140s have been modified with gear extenders, which aim to prevent these incidents by placing the wheels slightly ahead of the gear legs. While these do help to reduce the nose-over tendency, some owners and maintainers complain that they also introduce torsional flex to the gear, which can weaken and fatigue the attachment points to the fuselage. It’s wise to inspect this area closely during a pre-purchase inspection.

Later 140s and all 140As addressed the concern with redesigned gear legs that were themselves slightly swept forward to help counteract any nose-over tendencies. The gear attachment points on these models were strengthened accordingly to handle the torsional loads from the forward-swept gear.

Ultimately, the 120 and 140 provide a great introduction to tailwheel flying. With predictable handling, a very effective rudder and sturdy landing gear, they are forgiving to newcomers while still providing the endless satisfaction that comes from mastering a tailwheel aircraft.

Ray Huckleberry’s 140 after restoration.
Ray Huckleberry’s 140 after restoration. (Courtesy Ray Huckleberry/)

Ownership

Plenty of aircraft types provide a low operating cost on par with the 120 and 140, but few also offer the retro, 1940s-era character and tailwheel flair. Together, these characteristics combine to make every flight that much more interesting, rewarding and memorable than those in more common entry-level types such as the Cessna 150 and Piper Cherokee. Park one of the former on a ramp, and they’ll often go unnoticed; park a 140 on a ramp, and you’ll soon be making new friends as they meander over to swap stories and memories.

And while the 120 and 140 lack the necessary qualities for true STOL operations, many owners find it to be a rugged, reliable machine for accessing poorly maintained grass and dirt strips, particularly when larger tires are fitted. Indeed, without a relatively fragile nosewheel attached to the firewall, the simple and beefy main gear is poised to take significantly more abuse than tricycle gear counterparts. Additionally, pilots in colder climates can install skis to open up entirely different flying experiences and adventures.

It’s this blend of character and qualities that make the 120 and 140 stand out. Though easily surpassed in one measure or another on a spreadsheet, they demonstrate how an aircraft can fall short in many commonly held metrics while offering a wonderful blend of less tangible strengths. Provided an owner can live with a limited payload and leisurely performance, these are airplanes that keep their owners interested and enthusiastic for a long time. Indeed, many owners we know vow they’ll never sell theirs, and it’s not uncommon to hear those who have express regret that they did.


This story appeared in the March 2020 issue of Flying Magazine

Technicalities: I Sing the Airplane Electric

Gabriel DeVault with the electric Thunder Gull.
Gabriel DeVault with the electric Thunder Gull. (Courtesy Peter Garrison/)

As I taxi out, a crisp shadow follows on the taxiway beside me. I give a little burst of power, then pull the throttle lever back to idle. Out of the corner of my eye, I see the shadow of the prop stop. “Uh-oh,” I think. “The engine quit.”

But no.

The airplane is a pod-and-boom single-seat ultralight converted by Mark Beierle and Gabriel DeVault to electric power using components from a Zero electric motorcycle. This is the first electric airplane I’ve been in, and I’m learning its peculiarities. One of them is, on the ground, if you pull the throttle—well, power lever—all the way back, the prop stops. You have to be careful of people standing around because when the master switch (or “kill switch”) is on, the motor is on as well, even when the propeller is not moving. It can silently spring to life at an inadvertent bump of the throttle.

The flight instruments are the minimum required and conventional; the powerplant instruments, on the other hand, consist of digital displays showing how much power you have left, how fast you’re using it, and how hot various parts of the system are. Having arrived at the runway, I am briefly frustrated by the lack of anything to do before takeoff. There’s no run-up and nothing to check. Not only that—the airplane, being an ultralight and beneath the notice of the FAA, has no N number. “Ultralight taking Runway 20 for takeoff, straight-out departure,” I report, with a persistent feeling that something is missing.

DeVault has told me that the full-power climb is unexpectedly steep, and the airplane is somewhat nose-heavy, and so, when landing, I should fly it on rather than attempt to stall it on. I retain the first of these warnings and forget the second. He’s right; the angle of climb is impressive, as is the deck angle, and I’m not even using full power. I climb straight out to 1,000 feet and turn northward along the coastline of Monterey Bay in California. It’s a beautiful day, the scenery is lovely, Santa Cruz serenely puffs cannabis in the middle distance. There is no vibration, but the airplane is noisier than I expected. You imagine an electric motor will be practically silent, and maybe it is, but the propeller, chopping its way through the disturbed wake of the pod and wing, isn’t. (DeVault has posted a bunch of in-flight videos that give a good idea of it. Search for “Gabriel DeVault electric airplane” on YouTube.)

Electric cars added the phrase “range anxiety” to our vocabulary. Flying an electric airplane is like flying a conventional airplane when you’re down to the last hour’s fuel. But at least in the electric airplane you know precisely, to two decimal places, where you stand; there’s none of that “Does the width of the needle count?” feeling. DeVault told me to come back when I’m around 30 percent of charge. After 40 minutes in the air, I am there and do. My landing is atrocious. Forgetting I’m not supposed to stall it on, I let the plane develop too much of a sink rate and then find I don’t have the elevator authority to arrest it. After I collide with the runway, an inept dance on the heel brakes ensues. Luckily, the landing gear is pretty stout—DeVault says that Beierle, the airplane’s designer, demonstrates it by veering around on rough ground like an SUV in a TV ad.

Well, I thought, that was fun—except for the end.

The fuel of electric airplanes is kilowatts. The watt is a unit in the metric system—our light bulbs have been metricated all along—and is the power of one volt at a current of one ampere. A kilowatt is 1,000 watts and equals 1 1/3 horsepower. Eventually, you stop having to make conversions, but as a novice, I still multiply kilowatts by 4/3 to get back to familiar territory. (For instance: The 100-watt bulb in my reading lamp draws about 1/7 horsepower.) DeVault’s motor has a peak output of 45 kW (60 hp) but, at that level, will soon overheat; it can run continuously at around half that power, but only 10 kW is required to maintain a stately cruising speed of 55 knots.

DeVault prepares to plug in the battery for a recharge following the author’s flight.
DeVault prepares to plug in the battery for a recharge following the author’s flight. (Courtesy Peter Garrison/)

The battery capacity is given in kilowatt-hours. It is as if we measured the capacity of fuel tanks in horsepower-hours rather than gallons. A 50-gallon fuel capacity is around 650 hp-hr and will keep you aloft for five hours at an output of 130 hp. The lithium-ion battery, with about one-fiftieth of the per-pound energy capacity of avgas, stores around 11 kWh. Charging time is a function of supply voltage; a 220-volt outlet will top a completely drained battery in an hour, provided a 50-amp circuit is available (because 50 multiplied by 220 equals 11,000). At typical electric rates, the cost of a full charge is $1.20. Alternatively, a 20-by-25-foot patch of solar cells—retail cost around $7,000—will do the same for nothing, assuming the sun is shining.

Read More from Peter Garrison: Technicalities

The motors of electric airplanes are much lighter and more compact than comparable internal combustion engines. Their power output is limited by, among other things, rpm—which, in aviation applications, can’t exceed around 3,000 because of propeller-tip speed—and importantly, by cooling. Being so compact, electric motors do not have a large surface area to dissipate waste heat; high-performance motors use liquid cooling and sacrifice some of the advantage of their small frontal area to the need for a radiator.

The electric motor’s throttle is its “controller,” which looks like an old-fashioned hi-fi amplifier with cooling fins. The controller works by interrupting the flow of electricity from the battery to the motor with fast solid-state switches. The more power you ask for, the more of the time the switches are “on.” The tempo of the switching is so rapid, the flow of power appears to be continuous.

As everyone knows by now, lithium-ion batteries have just enough energy per pound to permit flight, if at only low speeds and for short distances. Partisans of electric airplanes regularly predict imminent increases in battery capacity, but for the moment, what gets from a battery to the propeller is about one-fifteenth, per pound, of what we get from avgas. There are battery chemistries that are considerably more power-dense than lithium-ion but lack its virtues of rapid rechargeability and long useful life.

(The difference between the one-fiftieth I mentioned earlier and the one-fifteenth in the previous paragraph is the fact that electric motors are about three times more efficient than piston engines.)

I have it on good authority that no fewer than 230 companies, worldwide, are developing one kind or another of electric aircraft. Many of these are of the short-range, multirotor, VTOL, urban-taxi variety, for which electric propulsion is uniquely suitable. How suitable pure electric—as opposed to hybrid—systems prove to be for other kinds of aircraft will depend on still-unforeseeable developments in battery technology. Where there’s a will, there’s a way—but it might be a long way.


This story appeared in the March 2020 issue of Flying Magazine

Super Tucano Takes First Flight for Nigerian Air Force Program

The A-29 Super Tucano has been selected by 15 air forces globally.
The A-29 Super Tucano has been selected by 15 air forces globally. (Courtesy Embraer/)

The newest Super Tucano took its first flight for the Nigerian Air Force program, Embraer and Sierra Nevada Corporation announced on April 17. Embraer Defense & Security joined forces with SNC on the project, which is undergoing testing at the venture’s production facility in Jacksonville, Florida. The A-29 Super Tucano is the first of 12 aircraft in production for the program.

“This is an exciting milestone in the production of these A-29s for the Nigerian Air Force. The Jacksonville production line is active, and Embraer and SNC look forward to seeing these aircraft continue to roll off the line in the coming months,” says Jackson Schneider, president and CEO for the Embraer Defense & Security division.

“The aircraft met or exceeded all the requirements and we are very pleased with the successful flight,” stated Ed Topps, vice president of Tactical Aircraft Systems and programs for Sierra Nevada Corporation’s IAS business area. “SNC and our partner, Embraer, are certain the Nigerian Air Force will be pleased with these aircraft.”

The light attack aircraft has been designed to be a cost-effective and reliable mount for basic and advanced combat flight training, making it well-suited to the Nigerian Air Force mission for the aircraft. The contract for the 12 airplanes was awarded in December 2018.