The dawn of practical electric airplanes is already a glow on the horizon, illuminated by prescient entrepreneurs like Roei Ganzarski.
Roei brought examples of his electric aircraft motors to the Paris Air Show in June. He and his MagniX company discussed three electric aircraft programs promising to fly starting this year.
An all-electric deHavilland Beaver floatplane is expected to make its first flight in Vancouver, B.C., by November. In the works is an electric Cessna Caravan. And a fascinating clean-sheet design, the French nine-passenger pressurized aircraft called Alice, has chosen to use three of MagniX’s electric powerplants.
Three such disparate aircraft share a common trait — they are used commercially for short commuter and freight hops. The Beaver and Caravan conversions have their usefulness as electric aircraft based on 100-mile legs, while the swift Alice is premised on 500-mile journeys, Roei explains.
MagniX computations indicate the battery recharging time will approximate the flight time of the previous leg. Aircraft like the Beaver will use $8 to $12 in electrical costs for a 100-mile flight, he figures.
Roei is optimistic about the future of MagniX in the aviation marketplace.
“There are 30,000 middle-mile aircraft in the world today,” he says, referring to aircraft that typically fly legs of 50 to 1,000 miles.
Just as internal-combustion-engine automobiles needed a fueling infrastructure before they could be practical, electric vehicles need properly spaced charging stations. Roei is mindful of efforts by electric car maker Tesla to install high-speed charging stations along major freeways to make their vehicles practical for cross-country travel. He figures his task will be easier. His target airplanes and the companies that use them have a few specific destinations rather than the boundless open highway network, and some airports already have automobile charging stations that can also serve aircraft.
Roei touts several benefits of his custom-built electric motors for aircraft.
The flagship Magni500 weighs in at less than 300 pounds and promises 750 horsepower at 1,900 rpm. This will power the upcoming conversions of Beaver and Caravan aircraft. The lightweight and small size of this motor (about 29″ from spindle to motor mount and less than 26″ top-to-bottom or side-to-side) make it easy to install and to streamline within the confines of existing airframes. The MagniX electric airplane motors are not altitude-limited by oxygen, as are internal-combustion engines.
Weighing less than half of a Beaver’s R-985 radial engine, the Magni500 can be mounted farther forward to aid in preserving the aircraft’s center of gravity, which is further balanced by placing some of the electric Beaver’s lithium-ion batteries in the engine compartment. The rest of the Beaver’s batteries reside in the fuselage space formerly used for gasoline.
The Magni500 has four three-phase windings, some of which can still operate even if one or more fail. Roei calls this “graceful degradation,” which allows the electric aircraft to keep flying to a safe landing spot in the event of motor problems.
This, in effect, gives a single-engine electric aircraft using a MagniX motor the redundant capability usually associated with a traditional twin-engine airplane, he says. The Magni500 provides direct drive to the propeller, removing the need for the expense and machinery of a gearbox.
One quirk attends the use of an all-electric airplane. A piston-powered Beaver loses weight for every gallon of gas burned, and this property can be a factor in load and distance planning. The battery Beaver retains its full gross takeoff weight throughout the flight. If that has the potential to put the electric aircraft too heavy for landing in some conditions, the available answers include different load planning, and an STC that can increase the plane’s gross landing weight, according to Roei.
The launch of a MagniX electric airplane is being undertaken by Harbour Air Seaplanes of Vancouver, B.C. Operating a fleet of Beaver and Otter floatplanes on relatively short hops, Harbour Air looks like the ideal candidate for an electric Beaver, which is on track to become the world’s first commercial electric aircraft. MagniX is headquartered in Redmond, Washington, not too distant from Harbour Air’s operation.
The other excitement at MagniX comes from the Eviation Alice commuter aircraft, a streamlined composite machine that makes good use of the small cross section of electric motors to put one Magni250 in the aft fuselage as a pusher and two Magni250s in the wingtips as tractors, delivering total power in excess of 1,000 horsepower. Alice is forecast to fly up to 650 miles at a cruise speed of 240 knots while carrying nine passengers in pressurized comfort.
If you’ve seen vehicles like Chevrolet’s recently touted electric Camaro dragster, you already know how heady the torque can be with electric power — no golf cart here. Roei says his aircraft installations will use a torque limiter to keep the acceleration within controllable bounds, though it should still be very quick.
Roei notes batteries are improving in capabilities by about 5% each year. That trend argues for ever-increasing range and performance for electric airplanes. Additionally, when aircraft using batteries recharge the batteries before depletion, they extend the useful life and capacity of the batteries, he says.
For now, MagniX is focused on fleet operators in the middle-mile market for electric conversions, as well as for the new-build Alice commuter. But he doesn’t rule out broader applications down the road.
“I think there will be a time in the future,” he says, for conversion kits for other general aviation aircraft on an individual basis.
With the acumen of a business professional, Roei Ganzarski is passionate about electric aircraft.
“This is so much more than ‘oh, it’s a cool electric plane,'” he says.
Thinking about it earlier this AM, another non-technical consideration but no less important problem with this idea of electric propulsion is that of fuel reserves.
Assuming the FAA eventually allows electric flight under FAR part 91, day VFR fuel reserves are 30 minutes and 45 minutes for night flight; rotorcraft require 20 minutes of reserve under 91.151. IFR fuel reserves are 45 minutes or 30 minutes for rotorcraft under 91.167.
So this means the Airbus Vahana is operating under reserves the second the blades start turning. The one-hour range Cessna Caravan would be under reserves either 15 or 30 minutes after the prop starts turning.
Now let’s turn to energy density one more time. George Bye is working with another Company to reach 0 .400KWh/kg and hoping for 0.500 Wh/kg energy density by weight. Let’s do the math to figure out what his magic 35KwH engine requires.. Using the higher (better) number, his 35KwH motor will require batteries weighing 70Kg or 154 lbs plus the weight of the control electronics and inverters. I don’t know what his electric motor weighs but it’s likely not as heavy as an internal combustion engine so there is a slight advantage there. If he were using gas to provide this energy, it’d be 18 pounds or 3 gals of gas (figuring a 33% energy loss with an internal combustion engine). 18 pounds vs 154 pounds. Say … an RV-12iS throttled back to 90mph would like be burning that exact amount of fuel … 3 gals/hr.
If there’s logic in here somewhere … I fail to see it. Say … I have shares I’d like to sell in a Bridge in NY … any electric airplane investors out there interested?
Here we go again … this guy is bound and determined to make me crazy!
One gal of gasoline is ~120,000 Btu of energy. One Kwh is ~ 3,412 Btu. So one gal of gas can produce about 35 Kwh of energy. One HP ~ 746 watts so 750 HP ~ 560 KW ~ 35 gals (210 lbs) of gasoline. Remember those numbers.
At Airventure 2019, the Airbus Vahana folks told me it uses eight 35Kwh electric motors so to make it run off of gasoline converted (I realize this assumes 100% efficiency), it’d take eight gals of gas which weigh 48 pounds and take up little space to allow it to fly for one hour. With today’s battery technology, Airbus says the Vahana can fly (autonomously) for 20 minutes with very heavy batteries aboard. What the heck are these people thinking (or smoking)? There’s no room for error or weather or other unexpected delays, either.
I attended George Bye’s presentation at the AOPA tent, as well. HE stated that he wanted people to remember that 35Kwh = 90mph for one hour flight in his two place trainer. Wonderful! I walked up and asked him the cost. Answer … too much for anyone but a flight school. OK … an airplane needing 35Kwh of energy to fly a training airplane for an hour … that’s doable at this time IF you can justify the cost of the machine.
Now extrapolate up to a 750hp electric motor. The numbers get SO big that my 4-function calculator can’t figure it out. They’re choosing a Caravan and a Beaver because the airplane will be filled with the weight AND volume of batteries. People are forgetting that energy density takes two forms … weight per unit energy and VOLUME per unit energy. I have a chart produced by the US Energy Administration which compares all sorts of forms of energy to gasoline which is assumed to be “1” both by unit volume and unit weight. Batteries are darn near zero on both counts that chart … translated for those from Rio Linda, CA … that means useless (at THIS time).
Just because you can build a usable electric motor to replace an internal combustion engine does not mean the airplane is useful without sufficient energy to run it. If I can find a link to that chart, I’ll put it here. And don’t forget that when you land, the weight of the power source is STILL the same; you’ve been lugging it around after the electrons are depleted.
At the Sabrewing forum at Airventure, the CEO showed a remotely flown hybrid airplane similar to the Vahana that would use a jet-A burning engine generating electrical power for four electric motors. Now THAT form of machine likely will succeed because they’re producing energy SO efficiently onboard and the motors use most of it to turn electrical energy into motive power. They’re not trying to carry batteries around to provide the energy (although I suspect there are some batteries just in case?).
Pure battery powered electric flight for a reasonable period of endurance is NOT POSSIBLE at this time … period. And when it is … the electric grid isn’t going to be able to handle the demands unless you build a nuclear reactor next to each recharging airport. Physics is physics and that’s that.
Someone should aptly point out that an internal combustion engine is only about 30% efficient at turning energy in ANY format into motive power. Fine. Multiply my numbers by three (to reach the efficiency of an electric motor) … that STILL means that gasoline is the finest way to carry vast amounts of energy in stored (by weight OR by volume) form that exists. That’s why only a hybrid designed to maximize efficiency will work at this time. IF it’s autonomous (or remotely controlled) the weight of the pilot and necessary accoutrements can be used for other purposes and advantages.
Now lets look at the Bye Aerospace eFlyer 2. Unit cost is ~$350K. I can buy a Van’s RV-12iS for 1/3 of that and fly for four hours sipping fuel at less than 4 gph with a modern day engine and for the difference of $230K, I can pay for a helluva lot of fuel, too. And — oh by the way — no charging time in between flights is necessary.
As I’ve said before … unless and until a battery that uses unobtanium or element 115 is designed which exceeds the volumetric or weight efficiencies of gasoline or diesel, pure battery powered electric flight is not going to be anything but a fantasy separating investors from their money.
Meanwhile, at my hangar I’m still waiting for Cessna and Bye Aerospace (then known as Beyond Aviation) to deliver my battery powered QEC for my C172 that they promised way back in 2010.
When Van’s comes up with an eRV-12, THEN I will believe all this wild blue yonder stuff.
Per the AMT Powerplant Handbook FAA-H-8083-32, “A pound of petroleum fuel, when burned with enough air to consume it completely, gives up about 20,000 BTU” “Of the total heat produced, 25 to 30 percent is utilized for power output, 15 to 20 percent is lost in cooling (heat radiated from cylinder head fins), 5 to 10 percent is lost in overcoming friction of moving parts; and 40 to 45 percent is lost through the exhaust.”
Assuming the higher efficiency of 30%, 120,000 BTU should give us roughly 10.55 Kwh of usable energy.
Obviously an electric motor will have losses as well. Tesla’s electric motors supposedly have an efficiency of ~ 93%. I would be surprised if these motors referenced are more efficient.
An electric airplane also has significantly less cooling drag which means less energy is required for flight than on an identical airplane with a reciprocating engine.
I agree that electric flight is not currently viable for a flight of a reasonable length, but it may be closer than we think.
That’s why I came back with my sub-comment, Wendell. We agree exactly that my “perfect world” 35KW/gal x 30% efficiency is 10.5KW/gal in ultimate useful work.
Most folks would have to agree that Tesla probably is as far ahead of anyone with electric cars. Using those numbers, a Tesla 85KwH battery pack would be the equivalent of about six gallons (36 pounds) of petroleum energy powering an internal combustion engine. Guess how much the 85KwH Tesla battery pack weighs … do ya’ll have your seatbelts on … 1,200 pounds ! In a car, it’s weight is less of an issue. In an airplane, weight IS the ultimate issue.
This guy has it exactly right:
science20.com/science_20/energy_density_why_gasoline_here_stay-91403
“That means a gallon of gas contains the energy density to power your television for 36 straight days – in a comparatively tiny package. How large a battery would you need to run a TV for 36 days? Gigantic.” (Either by weight OR by volume).
Nuff said.
“Roei notes batteries are improving in capabilities by about 5% each year.”
That means that electric airplanes should be practical within 50 to 100 years.
What is your calculation to support 50-100 year time frame?
(I’m not disagreeing I’m just curious to know where you got that wide range.)
It’s simply math. Say you want a 10x improvement, at 5% improvement per year. If the improvement is not compounding, it’s just 10/0.05 = 200 years.
If it is compounding, you use a different formula.
10 = 1.05 ^ X
If you take the natural log of each side you get:
ln(10) = ln(1.05^X)
The thing about exponents is you can move them out of the parenthesis and multiply the ln function it came out of to get:
ln(10) = X * ln(1.05)
Then divide both sides by ln(1.05) to get:
ln(10)/ln(1.05) = X
ln(10) = 2.3025851 (approx.)
ln(1.05) = 0.0487902 (approx.)
so X = 47.19363 (approx.) years to get a 10x improvement at 5% per year
and for 15x
we get 55 .5 years, approx.
20x gives 61 years.