February 2020
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.
1 reply
February 2020
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.
February 2020
▶ system
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.
February 2020
Presumably, the battery is tasked with providing enough backup power for an autorotation landing. I’m not all that rotorwing savvy, but I would think the final flare would require virtually 100% anti-torque for at least a few seconds.
1 reply
February 2020
▶ system
John, as I understand autorotation, that happens when the engine is producing no power to the rotor, thus no torque to correct for. But I’m not all that rotorwing savvy either. Either way, there should still be plenty of battery power available in event of an engine failure.
February 2020
Mac H. - True about torque during auto. (Auto rotation is usually the Emergency Procedure for loss of Tail Rotor thrust). But the Tail Rotor IS the main yaw control and would assist in choosing where to best land in a power off auto rotation. I hope by now, aviation has learned that LiFe batteries are safe enough (and lightweight) to be used as alternate electric power in the case of engine failure or alternator/generator failure.
Just observing the meteorological conditions, I’m wondering about Bell’s considerations for Tail Rotor icing. I DO like the thought of the requirement for only 3 of 4 rotors needed for full functionality.
1 reply
February 2020
▶ Matt_Bentson
Mac & Matt: Thanks for the correction. I was following the energy and took a wrong turn. Good example of coming up with a conclusion without thinking it through correctly 
