The Anonymous Widower

Airbus On Electric Flight

This page on the Airbus web site is all about electric flight.

This paragraph greets you.

Today, zero-emission flight is closer to reality than ever. Electric and hybrid-electric propulsion is rapidly revolutionising mobility technologies across industries, from automotive to marine. And the aviation industry is no exception. Airbus is committed to developing, building and testing electric and hybrid-electric future technology that will enable the aviation industry to significantly reduce the CO2 emissions of commercial aircraft.

A read of the whole section is recommended.

A lot of technology will need to be improved even to get say a 60-seat airliner, with a 500 mile range.

  • Design-changing efficient aerodynamics.
  • Lightweight, strong structures.
  • Efficient zero-carbon propulsion systems.
  • Batteries with a much higher energy capacity per kilogram of battery weight.

It’s a tough ask, but I believe it is possible!

We might even see some very unusual ideas. And some proven ones.

Catapults

Naval fighters are usually literally thrown into the air from aircraft carriers using aircraft catapults, which traditionally were steam-powered. Gliders are often towed into the air using a rope.

So could something similar be used to accelerate the aircraft to flying speed?

Taxiing And Take-Off Using A Tug

All taxiing would use a battery-electric or hybrid-hydrogen-electric tug to minimise use of energy from the plane’s batteries.

Could the tug be combined with charging and a vehicle to handle the catapult launch?

  • A fully-charged tug would meet incoming aircraft and tow them to the terminal.
  • The aircraft would use the tug for power, if it was low.
  • At the terminal, the tug and aircraft would be charged, during passenger unloading and loading.
  • On the taxi to the runway, all power would be provided by the tug.
  • The catapult system, would attach to the tug on take-off.
  • Once take-off speed was achieved, the aircraft would disconnect and climb away under its own power.

All the power for acceleration to take-off speed would be provided on the ground and the aircraft wouldn’t have to carry it.

Energy Calculations For An Airbus 220-100

The smallest Airbus aircraft is the A220-100, which has the following specification.

  • Passengers – 135
  • Maximum Take-Off Weight – 63.1 tonnes
  • Cruise speed – 871 kph
  • Take-off speed – 220 kph (estimated)
  • Ceiling – 41,000 ft.

Note that the design cruise speed of the nine-seat electric Eviation Alice is 482 kph at 10,000 ft.

Using Omni’s Kinetic Energy Calculator, the following values are obtained.

  • 220 kph – 32.7 kWh
  • 482 kph – 157 kWh
  • 981 kph – 513 kWh

As the kinetic energy is proportional to the square of the speed, I would expect that a small electric airliner would have a cruise speed slower than current airliners.

I would expect that Alice’s cruise at 482 kph and 10,000 ft., could have been chosen to get a decent range for the maximum size of battery.

The aircraft will also have to be given potential energy in the climb.

Using Omni’s Potential Energy Calculator, the following values are obtained.

  • 5,000 ft. – 262 kWh
  • 10,000 ft. – 524 kWh
  • 41,000 ft. – 2148 kWh

I would expect a small electric airliner  would fly a lot lower.

A 135-seat electric airliner, which is the same weight as an Airbus 220-100 and cruising at 482 kph and 10,000 feet would need the following energy to establish itself in the cruise.

  • Kinetic energy – 157 kWh
  • Potential energy – 524 kWh
  • Take-off energy at 220 kph – 32.7 kWh

Which gives a total of 681 kWh.

It should be noted that both the kinetic and potential energies are proportional to the maximum take-off weight. Assuming that take-off weight would be proportional to the number of passengers, rough estimates for the battery size needed.

  • 25 – 126 kWh
  • 50 – 252 kWh
  • 75 – 378 kWh

As Wikipedia says the smaller nine-seater Eviation Alice has a 900 kWh battery, I feel that at least a fifty passenger electric airliner is possible.

Very Efficient Aerodynamics

One of the biggest losses of energy will be due to less-than-perfect aerodynamics, with vortices, eddies and skin friction wasting precious energy.

Look at the pictures on the Internet of the Eviation Alice and you’ll see a strange aircraft.

  • A very pointed nose.
  • Two propellers at the wing-tips.
  • A third propeller at the tail.
  • I suspect, all the propellers are placed to get the most out of the power.

When Alice is cruising, her energy consumption will be minimal, so that the maximum range for a given battery size can be obtained.

Any electric airliner will draw on all the aerodynamic tricks in the book.

Efficient Flight Profiles

The longest flight, that I ever did in my Cessna 340A was from Southend to Naples.

  • Before take-off at Southend, the fuel bowser followed me to the end of the runway to give me a last-second top-up.
  • I travelled across France on a beautifully-clear day and the accommodating Lyon ATC allowed me to fly at 19,500 feet all the way to French Coast at Nice.
  • The French then decided that, as I was happy at that height, they would hand me over to the Italians without a change of level.
  • So I flew down the Italian coast past Genoa and Rome at 180 knots, with spectacular views all the way.
  • The Italians, then used radar to vector me on to final approach at Naples.

I reckon, I had flown nearly a thousand miles in if I remember correctly about six hours.

But it was a very efficient flight profile to get the range.

  • I took the maximum about of fuel, I could carry.
  • I climbed as fast as possible to an efficient cruising level.
  • I cruised at an efficient speed.
  • I used very little fuel on the descent and landing into Naples.

I certainly was pleased, that I had about another hour’s fuel left, when I arrived in Naples.

Electric aircraft will probably always fly efficient profiles, to get the maximum range. But they will all be calculated by the plane’s computer system.

Most Aircraft Are Heaviest At Take-Off

This is because they burn fuel in the engines, as they fly along.

But a full battery weighs the same as an empty one, so the electric aircraft will have the same flying characteristics in all stages of the flight.

This could have design and operational advantages.

Hybrid Propulsion

Some electric aircraft designs are hybrid, with both battery and turboprop power.

It still cuts carbon emissions and may give better performance.

Fuel created from biomass can also be used.

Conclusion

I expect to fly in an Aubus battery-electric short-haul plane between London and Geneva by 2030.

But I’m certain, I’ll fly before that in an electric aircraft.

 

 

 

 

 

May 20, 2020 - Posted by | Transport | , , , ,

4 Comments »

  1. Virgin Atlantic tried tug taxi on their bigger planes some years ago but discontinued I believe because the extra stress on the landing gear was creating extra maintenance costs that were not offset by fuel savings

    Comment by MilesT | May 21, 2020 | Reply

  2. Thanks. But we’re talking much smaller aircraft here!

    Comment by AnonW | May 21, 2020 | Reply

  3. an Airbus vp has been speaking at the (online) Farnborough airshow and says “we have the ambition to bring a zero-emission commercial airliner to market in the early 2030s” [up to 200 passengers, powered by hydrogen]. https://www.rechargenews.com/transition/airliner-fuelled-by-hydrogen-from-wind-and-solar-by-early-2030s-airbus/2-1-847144 https://www.thenational.ae/business/aviation/hydrogen-could-help-power-new-zero-emission-airbus-jet-1.1052622 He also said that Airbus need to partner with companies outside the air industry – which raises the thought of them and Alstom getting together.

    Comment by Peter Robins | July 23, 2020 | Reply

  4. Airbus have just released details of ZEROe, their latest concepts for zero-emission aircraft, powered by liquid hydrogen https://www.airbus.com/innovation/zero-emission/hydrogen/zeroe.html

    Comment by Peter Robins | September 21, 2020 | Reply


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