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-   -   Electric tail rotor; an alternative? (https://www.pprune.org/rotorheads/615965-electric-tail-rotor-alternative.html)

dClbydalpha 7th Dec 2018 12:29


Originally Posted by [email protected] (Post 10329971)
DcL - I'll take your word for the advancement of the technology - I'm just a guy who flys helicopters for a living not a boffin. but given these constraints how close are we really to seeing ETR in production?

Caveat that this is my personal WAG. If there is a will, I reckon 18 months to free flight. Realistically 3 years to an available production item. 5 years to realise the advantages?
The thing I see is that technology is advancing so fast that the move to hybrid and all electric may mean it's not worth the short term investments for just an ETR. Hence my comments about the next 10 years.

As I say, my opinion only .

SASless 8th Dec 2018 17:58

I have been reliably informed the UH-60 Blackhawk Tail Rotor can demand as much as 800 Horsepower.

How much would a 24VDC Electric Motor weigh in order to provide that much output?

What kind of gearing/gearbox/shafting would it require?

What Electric Load would it have to have feeding it....and what would the Generator/Alternator weigh for that?

Where would you place the Electric Motor along the Tail Boom not to have a CG Issue?


Let's carry this a bit further......what size motor would be required to power the CH-47F's Aft Rotor considering it already has two 4700 shp Engines driving the rotor system now.

IFMU 9th Dec 2018 03:39


How much would a 24VDC Electric Motor weigh in order to provide that much output?
What kind of gearing/gearbox/shafting would it require?
What Electric Load would it have to have feeding it....and what would the Generator/Alternator weigh for that?
it would not be 24VDC. More likely higher voltage AC.
800 HP is close to 600 kVA. A 250kVA B787 generator weighs a bit less than 300 lbs IIRC. Motors and generators are similar machines, so figure something like 600 lbs, unless somebody comes up with better technology. You should not need a gearbox for the UH60 tail rotor speed range with an electric motor.
you would need a big honking generator to run that 800 HP motor.

JohnDixson 9th Dec 2018 11:15

I think SAS wrote “ as much as.....” so that 800 number would be treated as a peak value, not steady state.

SASless 9th Dec 2018 11:24

Brother Dixson is correct that the demand would vary with the amount of Tail Rotor Thrust being applied or in the Chinook example what the Aft Rotor Head demand range could be from setting stationary on the Ground to lifting at Max Allowable Gross Weight.

If you think you need a big generator for the Hawk Tail Rotor....the Chinook application would be really huge!

gevans35 9th Dec 2018 11:38

Chinook is a different ball game, as is V22, although large hybrid VTOL multi motor tilt wing transport aircraft are suggested in various NASA articles.

Davey Emcee 10th Dec 2018 09:49

I expect James Dyson could find a solution.:)

Ascend Charlie 10th Dec 2018 17:40

...Dyson sucks...

ShyTorque 10th Dec 2018 23:09

But nothing sucks like an Electrolux.

mickjoebill 11th Dec 2018 03:09

If someone did come up with a bolt on spin recovery system (not a parachute!) for existing helicopters, would the industry adopt it?

Here is one hypothetical scenario:
Bolt on apparatus with no or min adaptions required to the air frame. Derigable.
Operates independently
Weight 30 kg (moving CoG rear of mast.)
Engauges automatically
Low maintenance
No other use but for countering the high speed yaw on light and medium helicopters.

At what price would such a safety device be considered too expensive?

For reference, we saw that despite the obvious benifits of crash resistant fuel cells for the r44, they were not widely retrofitted as a matter of free choice, due to cost.


mjb

Ascend Charlie 11th Dec 2018 05:04

30 kg on the tail would be a sizeable CG change - we used to put 10kg there to counter a massive camera on the nose. Without a camera, and 30 kg on the tail - fuggeddabardit!

Automatic engagement just invites undemanded deployment - that would be exciting.

No use for it, other than the 1:1million chance of a tail fail - no thank you, rather have 30kg more payload and a workable CG for the 999,999 other flights.


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