Flying Electric in the US
By Bill Lofton, EAA 0332319, [email protected]
Courtesy of EV Hangar
We’ve been treated to news releases about electric aircraft for years, yet headlines are still
focused on record-setting flights or latest developments of a prototype or proof-of-concept
aircraft, rather than news we can use to build and fly electric.
The following is my take on the status of electric aviation in the US in July 2013, including who
can fly electric, what aircraft are currently flying, and how to get your own. I’ve also included
information on developments toward electric LSAs and the issue of Part 103 and batteries.
Who Can Fly Electric in the US
The FAA has basically three US pilot categories:
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Private Pilot
Sport Pilot
Single Occupant
Yes, there are also commercial pilot and airline transport pilot certificates, but for recreational
pilots, a private pilot certificate is the most you need. As you might have guessed, Single
Occupant is the easiest pilot rating to achieve.
The FAA’s 14 CFR Part 103, which prescribes rules for “ultralight vehicles,” includes
requirements for the ultralight’s pilot.
Quoting the Part 103 source:
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103.1 Applicability.
This part prescribes rules governing the operation of ultralight vehicles in the United
States. For the purposes of this part, an ultralight vehicle is a vehicle that:
o (a) Is used or intended to be used for manned operation in the air by a single
occupant;
103.7 Certification and registration.
o (b) Notwithstanding any other section pertaining to airman certification, operators
of ultralight vehicles are not required to meet any aeronautical knowledge, age, or
experience requirements to operate those vehicles or to have airman or medical
certificates.
I said “Single Occupant,” right? Of course, “FAA requires” and “common sense dictates” are
two different things and I would be remiss if I didn’t point out the obvious, that no one should
ever takeoff in an ultralight aircraft before receiving proper training. No one.
Because battery technology, while greatly advanced in the last decade, is still low in energy
density relative to gasoline, early adopters of electric aviation are finding that most of the
currently available electric aircraft are ultralight aircraft. So a Single Occupant will do very well
indeed.
A Sport Pilot certificate, good for piloting Light Sport Aircraft, won’t get you up in an electric
aircraft because there aren’t any electric Light Sport Aircraft yet.
That leaves type certificated and experimental aircraft, and a private pilot certificate is required
for both. Only a couple of the currently available electric aircraft are type certificated, so a
private pilot certificate doesn’t gain you many choices there. But the experimental aircraft
category is an electric aviation treasure trove and because of that, private pilots will enjoy many
choices over Single Occupants for a long time to come.
The point is… anyone can fly electric in the US!
US-Legal Electric Aircraft
In the US, all aircraft flown legally must satisfy FAA
requirements for one of the following aircraft categories:
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Type Certificated
Experimental
Light Sport
Ultralight
Because the FAA’s Light Sport Aircraft definition requires
“a single, reciprocating engine,” no electric aircraft have been
designated Light Sport Aircraft. So electric aircraft that can fly
legally in the US can be grouped as:
Courtesy of ElectraFlyer.com
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Electric-powered type certificated
Electric-powered experimental
Electric-powered ultralight
The category of a given electric aircraft matters because it determines, among other things,
whether or not you need a pilot’s license and medical certificate to legally fly it in the US
Ultralights can be flown legally without pilot’s license or medical certificate. The other two
categories–type certificated and experimental–require both pilot’s license and medical certificate.
Electric aircraft flying in the US:
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Electric-powered Type Certificated
o Antares 20E (Lange Aviation)
production aircraft, US type certificate
o Arcus E (Schempp-Hirth)
production aircraft, US type certificate
o Taurus Electro G2 (Pipistrel)
production aircraft, US type certificate
Electric-powered Experimental
o ElectraFlyer-C (Electric Aircraft Corporation)
proof-of-concept aircraft, experimental
o ElectraFlyer-X (Electric Aircraft Corporation)
prototype aircraft, experimental but intended to become LSA
o Electric Waiex (Sonex Aircraft)
proof-of-concept aircraft, experimental
o ESpyder (GreenWing International)
prototype aircraft, experimental but intended to become LSA
o Silent 2 Electro (AliSport)
production aircraft, no planned US type certificate, but does have a kit for US
experimental designation
Electric-powered Ultralight
o eGull 2000 (Earthstar)
prototype aircraft, Part 103-compliant ultralight
o eLazair
prototype aircraft, Part 103-compliant ultralight with a battery allowance
o ElectraFlyer Trike (Electric Aircraft Corporation)
production aircraft, Part 103-compliant ultralight
o ElectraFlyer-ULS (Electric Aircraft Corporation)
production aircraft, Part 103-compliant ultralight with a battery allowance
o Electric Pit-Trike (Icaro 2000)
production aircraft, Part 103-compliant ultralight
o ElectroTrike (Electravia)
production aircraft, Part 103-compliant ultralight
o ES Trike (Electric Sports)
production aircraft, Part 103-compliant ultralight
o
o
Silent Glider (Silent Family)
production aircraft, Part 103-compliant ultralight
Voyager ElectraChute (PowraChute Corporation)
proof-of-concept aircraft, Part 103-compliant ultralight
Electric aircraft flying outside the US:
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Not yet legal to fly in the US
o Alatus ME (Aerola)
production aircraft, no known US type certificate or kit for experimental
designation, could be LSA, could be ultralight with a battery allowance
o Electric PhoEnix (Phoenix Air)
proof-of-concept aircraft, no US type certificate or kit for US experimental
designation, could ba an LSA (The Phoenix Air is S-LSA approved)
o Elektra One (PC-Aero)
prototype aircraft, no US type certificate or kit for US experimental designation,
too fast for ultralight, could be LSA
o E-Star 2 (Diamond Aircraft)
proof-of-concept aircraft, no US type certificate or kit for US experimental
designation
o E-Viva (Yuneec International)
prototype aircraft, no US type certificate or kit for US experimental designation,
could be an LSA
o e430 (GreenWing International)
prototype aircraft, no US type certificate or kit for US experimental designation,
could be LSA
o e1000 (Yuneec International)
prototype aircraft, no US type certificate or kit for US experimental designation,
beyond LSA and ultralight, would need type certificate or kit for Experimental
Amateur-Built
o FlyNano (Fly Nano Oy)
prototype aircraft, no US type certificate or kit for US experimental designation,
too fast for ultralight, could be LSA
o SportStar EPOS (Evektor Aerotechnik)
prototype aircraft, no US type certificate or kit for US experimental designation,
could be LSA (the SportStar Max is S-LSA approved)
How Can I Get an Electric Aircraft?
Courtesy of Zenith Aircraft and Sonex Aircraft
As with gas powered aircraft, the possibilities for obtaining an electric aircraft include:
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Buy ready-to-fly (new or used)
Build
For electric aircraft, as with EV automobiles, another possible route is:
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Convert from gas powered
The aircraft models we can buy new include type certificated and ultralight aircraft. The aircraft
models we can buy used include type certificated, experimental, and ultralight aircraft.
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Buy ready-to-fly new:
o Type Certificated
o Ultralight
Buy ready-to-fly used:
o Type Certificated
o Experimental
o Ultralight
Because currently flying electric aircraft are relatively new and in demand, the used electric
aircraft market is obviously limited. (By the way, Randall Fishman’s ElectraFlyer-C proof-ofconcept airplane N123EL is for sale.)
The Barnstormers online aircraft marketplace recently added an Electric Aircraft main category
and Electric Aircraft subcategories under their Experimental and Ultralight main categories in
their classified ads, but it’s early yet. Don’t expect to quickly find a used electric aircraft.
Unless you’re an aircraft manufacturer, you won’t be able to build a type-certificated electric
aircraft. That leaves experimental and ultralight aircraft as candidate electric aircraft for the
home builder. To date, no kits are available for experimental amateur-built (E-AB) or ultralight
electric airplanes. However, kit manufacturers usually price the powerplant separately, so adding
electric propulsion to an existing kit is a reasonable path to electric flying.
The current options for a home builder of an electric aircraft are:
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build from a kit (or plans) for an experimental or ultralight aircraft intended to use gas
propulsion and adapt the kit (or plans) to electric propulsion
convert an existing “donor” experimental or ultralight aircraft to electric propulsion
Building from plans is not for the weak of heart. And with all of the great kits available today,
there’s no reason not to take advantage of the work their manufacturers have done.
You shouldn’t be on your own if you choose a currently available kit intended to use gas
propulsion and make necessary modifications for electric propulsion. The kit’s manufacturer
should be supportive of your modifications by crediting you for unneeded kit components and
helping you with design (and maybe development) of newly needed kit components. After all,
they want your business and they should be very interested in adding electric propulsion to their
future offerings. Likewise, converting a used kit-based aircraft should gain similar support from
the kit’s manufacturer. Of course, it would be nice to find that out before you commit to the
project.
Before buying a kit intended to use gas propulsion or a used kit-based aircraft for conversion,
talk with the kit’s manufacturer about electric conversion to determine if they would be
supportive of your modifications. You can still accomplish the build or conversion without help
from the kit’s manufacturer, but knowing if you can expect their support should help with your
decision to start the project.
In summary, your current options for getting your own electric aircraft are:
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type-certificated electric aircraft:
o buy ready-to-fly new or (good luck) used
experimental aircraft:
o buy ready-to-fly (good luck) used
o buy new kit and build/adapt
o convert used “donor” airplane
ultralight aircraft:
o buy ready-to-fly new or (good luck) used
o buy new kit and build/adapt
o convert used “donor” airplane
Electric LSA Status
Effective on September 1, 2004, an update to the FAA’s Title 14, section 1.1 of the Code of
Federal Regulations (14 CFR 1.1), includes the following:
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Light-sport aircraft means an aircraft, other than a helicopter or powered-lift that, since
its original certification, has continued to meet the following:
o
(6) A single, reciprocating engine, if powered.
Notwithstanding the requirement for powered LSA to have a single reciprocating engine, interest
in early efforts to convert recreational aircraft to electric propulsion led the ASTM to direct their
Committee F37 on Light Sport Aircraft to prepare a standard for electric propulsion of LSAs. In
March 2011, Committee F37 issued the ASTM F2840-11 Standard Practice for Design and
Manufacture of Electric Propulsion Units for Light Sport Aircraft.
The FAA subsequently reviewed ASTM F2840-11 and on April 23, 2012, announced FAA
acceptance of ASTM F2840-11, effective immediately.
However, acceptance of ASTM F2840-11 Standard Practice for Design and Manufacture of
Electric Propulsion Units for Light Sport Aircraft does not mean immediate removal of the 14
CFR 1.1 requirement for “a single, reciprocating engine, if powered.”
According to an April 27, 2012 engadget report, at the 2012 CAFE Electric Aircraft Symposium,
the FAA’s Tom Gunnarson said the FAA will begin making rules for electric light sport aircraft
soon, but he also said it will take five to 10 years to update the regulations.
In the meantime, electric flying is available in type certificated, experimental amateur-built (EAB), and ultralight aircraft. However, batteries aren’t addressed in the FAA’s weight limit for
ultralight aircraft. But that’s another story.
Reporting points:
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9/1/04: An update to the FAA’s 14 CFR 1.1 to define light sport aircraft becomes
effective.
4/28/08: Aero News Network reports that Craig Willan, EAA lifetime member, said the
EAA asked the FAA to authorize electric propulsion for ultralight vehicles and light sport
aircraft.
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12/18/09: Popular Mechanics reports that the FAA’s Steve Flanagan, co-author of the
LSA Rule, said he wants more flight experience with electric motors before revising the
LSA rules.
March 2011: ASTM publishes ASTM F2840-11 Standard Practice for Design and
Manufacture of Electric Propulsion Units for Light Sport Aircraft
7/27/11: AV web reports that the ASTM’s Adam Morrison, vice chairman of ASTM
committee F37 (for LSAs), says that beyond ASTM F2840-11, the committee intends to
provide detailed guidance for installing electric propulsion units in light sport aircraft.
4/23/12: The FAA accepts ASTM F2840-11
4/27/12: Engadget reports that the FAA’s Tom Gunnerson says the FAA will begin
making rules for electric light sport aircraft soon, but that it will take five to 10 years to
update the regulations.
Part 103 and Batteries
For a given amount of stored energy payload or “fuel on-board,”
gasoline is still far cheaper that batteries in both weight and dollars.
(Although you don’t have to buy more batteries after each flight.) So
if battery-stored energy is crazy expensive, what do we do if we want
to fly electric now? We use as little energy as possible in our aircraft.
That means we need small or efficient aircraft. Or small and efficient
aircraft. Sport aircraft manufacturers are working on both fronts.
Today’s production and prototype electric aircraft are ultralights,
motorgliders, or both.
Courtesy of Icaro2000.com
Electric ultralights have a problem, though. Batteries aren’t mentioned in the FAA’s 14 CFR Part
103, which prescribes rules for “ultralight vehicles” that we can fly without a license. Part 103
does mention fuel, though. It says we can carry up to five gallons of fuel and it isn’t included in
the 254 pound empty weight limit.
Quoting the Part 103 source:

103.1 Applicability.
o (e) If powered:
 (1) Weighs less than 254 pounds empty weight, excluding floats and safety
devices which are intended for deployment in a potentially catastrophic situation;
 (2) Has a fuel capacity not exceeding 5 US gallons;
 (3) Is not capable of more than 55 knots calibrated airspeed at full power in level
flight; and
 (4) Has a power-off stall speed which does not exceed 24 knots calibrated
airspeed.
Hmm. Shouldn’t we get a battery weight allowance if we don’t carry our allowed five US
gallons of fuel? Seems reasonable enough. And many of us have expressed opinions on how to
interpret Part 103′s “Has a fuel capacity not exceeding 5 US gallons” clause.
Our various batteries vs. gasoline “equivalent fuel” interpretations of Part 103 fall into the
following categories:
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equivalent weight
equivalent volume
equivalent energy storage
equivalent range and endurance
Equivalent weight proponents point out 5 US gallons of gas weighs 30 lbs, so the fueled
ultralight at the 254 lbs empty weight limit weighs 284 lbs and that should be the allowed takeoff
weight of an electric ultralight with charged batteries. This allowance isn’t too wonderful for the
electric crowd though, because 30 lbs of batteries won’t keep you aloft more than maybe 30
minutes using currently available batteries.
Equivalent volume proponents assert that “gallon” is a volume unit (i.e. 1 US gallon = 0.1337
cubic feet), so electric ultralights should be allowed 5 x 0.1337 = 0.6685 ft3 of batteries that
aren’t included in the 254 lbs empty weight limit. This is more generous than the 30 lbs
equivalent weight allowance, since 0.6685 ft3 of lithium-ion batteries weighs about 65 lbs, but
that’s still less than the energy in 5 gallons of gas.
Equivalent propulsion energy storage and equivalent range and endurance each get at the heart of
the matter, which is to keep your electric ultralight aloft as long as the gas-powered ultralights.
But these metrics would require quite different means of verification for individual ultralight
vehicles than empty weight and battery volume. And of course as battery technology improves,
these values would change for visually similar battery packs.
In 2012, an appeal was made to the FAA in Washington to exempt battery weight from the 254
lbs empty weight limit for ultralight vehicles. The FAA responded with a letter stating that
batteries would not be excluded from an ultralight vehicle’s empty weight. (Brian and Carol
Carpenter posted the FAA assistant chief counsel’s response on their Rainbow Aviation Services
website.) For that FAA employee on that day, no “equivalent fuel” interpretations are valid.
Further, many have suggested that any reopening of Part 103 to explicitly address electric
propulsion of ultralights would result in FAA review of all of Part 103. And that could mean an
introduction of pilot training and medical requirements to Part 103.
For now, ultralight manufacturers are proceeding with development using their own Part 103
interpretations, ranging from no allowance for batteries to five US gallons volume allowance for
batteries. FAA ramp checks for fat ultralights could become very interesting as electric
ultralights become commonplace.
Bill Lofton is an engineer living in the Maryland suburbs of Washington, D.C. Bill found his
electric aircraft project planning hampered by a lack of organized information on electric
aircraft, systems, and components, so he researched and organized everything he could find.
Then he created http://www.evhangar.com/ “so early adopters of electric flying can share
information and experiences and learn what’s available and what’s coming.”
Bill drives a John Deere Gator TE electric utility vehicle.