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Electric tail rotor; an alternative?

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Electric tail rotor; an alternative?

Old 1st Dec 2018, 23:37
  #41 (permalink)  
 
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Some interesting reading.

Overview of NASA Electrified Aircraft Propulsion Research for Large Subsonic Transports.
https://ntrs.nasa.gov/archive/nasa/c...0180000361.pdf

GRC3: Integration of Innovative Electrical Systems for Rotorcraft (pages 12 & 13)
http://cleansky.eu/sites/default/fil...eport_2015.pdf

But are helicopters the future?
http://evtol.news

Upcoming lecture by Nick Lappos.
https://vtol.org/news/lappos-selecte...olsky-lecturer
.

Last edited by gevans35; 2nd Dec 2018 at 07:45.
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Old 1st Dec 2018, 23:37
  #42 (permalink)  
 
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Sadly TC, as so often is the case, this forum has been invaded by many armchair flyers who have no idea about actual operational Air operations . Best leave to their playtime air ops games!

TF
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Old 2nd Dec 2018, 00:02
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Originally Posted by tigerfish View Post
Sadly TC, as so often is the case, this forum has been invaded by many armchair flyers who have no idea about actual operational Air operations . Best leave to their playtime air ops games!

TF
Or those who have no idea how these magnificent flying machines are designed or certified.
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Old 2nd Dec 2018, 00:22
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Just to make it clear, my comment about autorotation was with the assumption that the generator would then be dead, and putting enough heavy and possibly explosive batteries in a helicopter to have that as a backup doesn't seem remotely realistic to me. I didn't think of that the gearbox could drive the generator, which I realize now would be the only sensible thing to do.

The autorotation comment was just meant as an example of new problems that would arise with such a "hybrid" system. I still think the main points are that I can't imagine that such a system as a total would be as reliable as a driveshaft and a gearbox, and that it would be much less efficient. I could be wrong, but I still have a hard time seriously thinking of electrifying the TR to reduce the risk of failure.
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Old 2nd Dec 2018, 00:43
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You do know you can autorotate with or without a working tail rotor right?
Very true except the levels of controllability will be different - there is a certain amount of drag within the drivetrain and auxiliary systems (HYD pumps, cooling fans, sometimes generators or alternators etc ) that are driven that will induce the cab to catch up with the main rotor. Also noticeable when you flare to prior to touchdown. Without a TR it will be a bit messy.
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Old 2nd Dec 2018, 02:56
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Old 2nd Dec 2018, 04:13
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Suppose you have to hover next to a cliff or hangar with some serious crosswind. Consider the following:
Is a fixed pitch variable speed electric motor dynamic enough to hold the tail steady? What about tail rotor rpm wind down when the gusts abate, do you need tail rotor brakes?
Perhaps variable pitch constant speed is the better electric option of the two. Now how do you manage power available on two different systems. Will the electric motor run out of puff while the coal burners are just warming up? Are bigger electric motors needed along with all the penalties that introduces?

Some of us like to roll the helicopter in tiny amounts just using the pedals, will the electric fan at the back take this away from us?

Now if you are gunna stick an electric fan at the back at least allow it to pivot around 90 degrees to provide forward thrust.
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Old 2nd Dec 2018, 08:34
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Originally Posted by dClbydalpha View Post
How much did you pay for it? What kind of certification did you get with it?

I overpayed obviously. I thought Walmart had the best price, but then I found it at Best Buy for less. #rippedoff
there was a sticker inside the airframe. Mostly in Chinese that had Insp.45 on it. I assume this was the manufacturer QA inspector. I bet he knows his stuff.
the things I learned on this thing would shame Chuck Aaron and his 105. He's got nothing on me.
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Old 2nd Dec 2018, 08:41
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First they ignore you, then they laugh at you, then they fight you, then you win.

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Old 2nd Dec 2018, 08:53
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I like this idea, main problem I can see is the tail rotor will have to keep spinning in flight otherwise there could be damage to the tail rotor blades or mechanism during start up and slow down.
Perhaps a ducted one would be superior????
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Old 2nd Dec 2018, 12:02
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Originally Posted by timprice View Post
I like this idea, main problem I can see is the tail rotor will have to keep spinning in flight otherwise there could be damage to the tail rotor blades or mechanism during start up and slow down.
Perhaps a ducted one would be superior????
Could be designed to windmill as a generator perhaps?

Last edited by chopjock; 2nd Dec 2018 at 12:13.
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Old 2nd Dec 2018, 12:24
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if these things that might appear ludicrous aren't looked at then nothing goes forward. I remember my basic rotary wing instructor at Wallop told me ( he started as a Sycamore pilot ) that they thought it was impossible to put a gas turbine in a helicopter when he started in the 1950's. That idea was obviously a non starter as well
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Old 2nd Dec 2018, 12:30
  #53 (permalink)  
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The assumption that a motor would be as heavy as a TGB, IGB, MGB tail pickoff and driveshaft is not one that I would make.
I'd like to see the weights. I'm imagining a pretty heavy motor, compared to the present drivetrain, plus the need for either a heavy generator, or batteries, and some heavy wire. By placing the heavy motor at the end of the tailboom, the tailboom will have to be made much more strong, thus heavy itself, and that will create an undesirable mass distribution for the whole fuselage. The available torque of a motor to drive an effective tail rotor would have to be immense to accelerate the tail rotor RPM commensurate with the pilot's possible sudden application of lots of pedal. For aircraft which carry batteries as a power source to replace fuel, a disadvantage is that when the batteries become discharged, they don't weigh any less. The component and control for electric motors would have to satisfy a evaluation of reliability to the standards of 27/29.1301 and 1309, which is daunting.

I am a helicopter pilot, and have undertaken design studies for an electric powered Cessna 172 STC (program may continue) and an electric powered R22 (program will not continue). Electric power in aviation has a bright future, in a rather narrow band of application, which I opine does not include helicopters in the foreseeable future.
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Old 2nd Dec 2018, 12:34
  #54 (permalink)  
 
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Let's not get too ambitious. Simply replacing the mechanical drive gives enough options for now.

If we're blue sky thinking I'd look at a ducted fan that could rotate to become a pusher.
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Old 2nd Dec 2018, 12:47
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Originally Posted by Pilot DAR View Post
Electric power in aviation has a bright future, in a rather narrow band of application, which I opine does not include helicopters in the foreseeable future.
I would agree with you if it's pure electric power, but a hybrid VTOL aircraft powered by electric motors, with a battery or capacitors, replenished by a gas turbine or diesel generator, may be viable in the not to distant future?

Edit: Here's an example...
https://newatlas.com/rolls-royce-evtol-air-taxi/55466/
.

Last edited by gevans35; 2nd Dec 2018 at 13:40.
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Old 2nd Dec 2018, 12:49
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Originally Posted by Pilot DAR View Post
... which I opine does not include helicopters in the foreseeable future.
That depends on the advantages gained, I personally think that an ETR brings a lot to the table in terms of efficiency and noise.

Motors, generators and actuators are already used, so we know how to design for certification, nothing daunting there.

As has been pointed out previously the technology is already here. It's simply about the investment.
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Old 2nd Dec 2018, 13:16
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  • I'm sure there's a lot of computer control in most modern helicopters already, but this would have to be entirely computer controlled to be at all flyable. That would open up a new can of worms when it comes to safety. I know that "fly-by-wire" is popular these days, but personally I only consider it "safe" as long as everybody is equipped with ejection seats.
I don’t accept your first premise - an electrically driven tail rotor, (whether feasible or not), could still be manually controlled.

As to fly-by-wire; so I take it that you don’t fly on any Airbus and only on some Boeings and turbo-props?

Airbus 320 family and 330 each have 5 FBW computers, and can remain flying aloft without any of them.

PS: can helicopters have ejection seats ??
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Old 2nd Dec 2018, 13:19
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PIlot DAR,

I am curious to know the weight and horsepower of an electric motor suited to a Cessna 172 retrofit.

CAn you give us a ballpark range?
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Old 2nd Dec 2018, 17:21
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I vote for ion propulsion. It's way cooler.
imagine the 505 as the launch model? Damn conflicted feelings there. Butt ugly but cool.
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Old 2nd Dec 2018, 17:24
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Originally Posted by Washeduprotorgypsy View Post
PIlot DAR,

I am curious to know the weight and horsepower of an electric motor suited to a Cessna 172 retrofit.

CAn you give us a ballpark range?
google helped me find this:
https://www.flyingmag.com/news/two-place-electric-cessna-172-skyhawk
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