• Bell Tests Electric Tailrotors

    From Larry Dighera@21:1/5 to All on Mon Feb 24 04:56:52 2020
    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.

    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

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