Bell Tests Electric Tailrotors
Russ Niles February 22, 20203

Video: https://youtu.be/jJUgmeSYox4

Bell Helicopters unveiled a 429 modified with four electrically driven
tail rotors that it says has proven the concept over almost a year of
testing. The Electrically Distributed Anti-Torque (EDAT) system has
been flying since last May from the company’s Mirabel, Quebec,
facilities and it works just fine. “This is the first time anyone in
the world ever done this, so the first step was just to make sure that
it actually works—and yes it does work,” Eric Sinusas, Bell’s light
aircraft program director, told Vertical Magazine. Each rotor has its
own motor powered by a generator on the Pratt&Whitney PW207 engines
and their thrust is modulated depending on the demands created by the
torque created by the main rotor.

While it adds a new system to the helicopter, EDAT also eliminates the
maintenance-heavy shaft and gearbox assembly that drives the tail
rotor of regular helicopters, while adding redundancy. Three out of
four fans is enough to control the helicopter. The fans are controlled
by the fly-by-wire system and can spin in both directions, making the
precise application of anti-torque force possible. That, says Bell,
cuts noise and makes the aircraft more efficient.



3 COMMENTS
Larry S. February 23, 2020 at 4:17 am
I’d be interested in knowing if the NOTAR idea could be employed on
this machine and — if so — what the weight advantages or penalties
would be compared to this EDAT idea. What is the weight advantage of
EDAT over the mechanical system it would potentially replace. Finally,
have any reliability analyses been done to determine the relative
advantage of EDAT? If it simplifies the tail rotor function but isn’t
110% reliable, what’s the point?

Actually, this may well be the first application of an electrically
driven system that makes sense to me based upon the limited
description here.

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Tord E. February 24, 2020 at 5:05 am
That is true, as we know nothing about its failsafe mode, are they
driven by a totally different bus and generators, that produce power
as long as the rotor turns, which should be the safe way of doing
things, or is it just an add-on to the main bus, thus fails as soon as
the normal bus goes belly up?!

NOTAR is an interesting McDonnell-Douglas patent and I doubt very much
that they would let Bell use the system or vice versa.

Having worked around helicopters as a heliguard on platforms and rigs
I know very well that tail rotors are a deathtrap, that just too many
have walked into, or been hit by during crashes, not to mention the
driveshafts and gearboxes that at times sheer off, or overheat, and
prove an extra hazard during an emergency landing.

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YARS . February 23, 2020 at 6:13 am
Equivalent level of safety?
If the vehicle already is full-on fly-by-wire (no mechanicsl
connections), then ELS may be a given. If not, then the
failure-mode-analysis game is on: likelihood versus consequences; same
as it ever was. Interesting, for sure. And apropos in a world of
quadcopters.

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