The Anonymous Widower

Opinion: Why Aviation Needs to Go Green, and How

The title of this post is the same as that of this article on Aeronautics Online.

Read the article and especially what it says about the Wright Electric Jet.

This is a paragraph from Wikipedia, talking about co-operation between Wright Electric and easyJet.

In September 2017, UK budget carrier EasyJet announced it was developing an electric 180-seater for 2027 with Wright Electric. Wright Electric built a two-seat proof-of-concept with 272kg (600lb) of batteries, and believes that batteries can be scaled up with substantially lighter new battery chemistries: a 291 nautical mile (540km) range would suffice for 20% of Easyjet passengers. Wright Electric plans to develop a 10-seater and eventually an at least 120 passengers single-aisle, short-haul airliner and targets 50% lower noise and 10% lower costs.

I would assume, that the plane also emits a lot less CO2 and other pollutants.

I would assume that the plane will be built by using the best of these technologies.

  • Aerodynamics
  • Lightweight structures
  • Electric Motors
  • Batteries
  • Electronics and avionics.

But I also believe that designing an electric aircraft could be a very different process to a conventional one.

There Is No Fuel

Consider.

  • Fuel is a high proportion of the weight of an airliner on take-off.
  • There are a lot of complicated systems to pump fuel to the engines and also from tank to tank to trim or balance the aircraft
  • When a conventional airliner takes off, it is much heavier than when it lands, as fuel has been burned.
  • Fuel is dangerous in a heavy landing or crash.

On the other hand, I’m fairly certain, that empty batteries and full ones weigh the same.

This would mean, that the plane aerodynamics and structure,  would be designed to be optimal in the various phases of flight.

  • Taxiing out to the runway.
  • Taking off.
  • The climb to the cruising altitude.
  • The cruise
  • The descent to the destination airport.
  • The landing
  • Taxiing in to the terminal or stand.

In the climb, cruise and descent  phases power would be set and the trim adjusted, by the autopilot to attain the right speed and rate of climb or descent.

Aerodynamics

As the weight of the aircraft would be the same in all three phases and would need more or less the same lift, with clever aerodynamics, I think we will see a very simple wing. In fact, probably more like that of a sailplane than an airliner.

Wikipedia says this about the design.

The aircraft is to run on batteries and handle flights of under 300 miles. It will feature high aspect-ratio wings for energy efficient flight, distributed electric propulsion and swappable battery packs with advanced cell chemistry.

Note that sailplanes have high aspect ratio wings.

Compared to say a small jet airliner like an Airbus A318, I suspect that the wings will be longer, but possibly simpler.

The Wright Electric Jet will probably have various aerodynamic aids, like flaps and winglets. In fact the picture on Wikipedia shows the latter, which reduce drag.

A Simple Flight Profile

The fastest way to fly between A and B is probably to take off and climb as fast as possible to the optimum cruising altitude, where an optimum cruise is maintained, until the time comes to descend into the destination airport. Much of the descent would be straight in to the runway.

I have flown in an easyJet Airbus 320 from Schipol to Southend in much this manner and the plane arrived ahead of schedule.

I suspect that easyJet like to fly like this, as it saves fuel, but Air Traffic Control probably doesn’t allow it that often.

But simple efficient profiles like this would be ideal for electric aircraft.

If as I suspect their aerodynamics would allow a better glide ratio than a jet powered airliner. So to get a longer range, an electric aircraft might do a long approach.

A Low Noise Aircraft

As I said earlier, Wright are talking about fifty percent less noise.

This could be a game-changer for a smaller airport like Luton or Southend, where the approach can be over residential areas.

Especially for Southend, where planes from the East could do a long descent over the sea and come straight in on Runway 23.

Could Southend become London’s short-haul airport for electric aircraft?

  • easyJet and Ryanair are already there.
  • There’s plenty of wind power in the area
  • It has a good rail connection to London and could be served by Crossrail.

Essex is a county that likes to be different.

Airbus

The original article also mentions Airbus.

Airbus has the skills to design the required light and strong airframe, the aerodynamic knowledge.and a large support network.

They also have a lot to lose, if someone else takes away, the smaller part of their masrket.

Ignore Airbus at your peril.

Conclusion

The more I think about it, the more that I think a 120 passenger electric airliner with a range of 540 km, could be a very handy plane.

 

 

December 10, 2019 - Posted by | Transport/Travel | , , , , ,

3 Comments »

  1. I think a totally fuel-free aircraft operating at the higher altitudes necessary for range, smooth flight, and safety may not be feasible. While we can eliminate fuel from propulsion, the interior of the aircraft (and some of the flying surfaces) need to be heated to safe and comfortable temperatures–it’s very cold at altitude.

    Today, this heating is largely done as a byproduct of fuel based engines (radiators, turbine bleed air); this heating would be a large continuous draw on the batteries, so may need to still carry and burn a small amount of fuel just for heating.

    This is a problem at ground level also, with current generation of battery buses usind diesel for winter heating to save battery for operating range (in London at least–the battery BYD/Dennis Enviro200EV single deck buses now rolled out to route 46 have diesel based heating for winter). In hot countries there would need to be some sort of cooling, maybe forced air with water evaporation instead of closed circuit compressors with gas refrigerant (cooling is a power a power draw, water is a weight).

    There is also an additional weight saving in an all electric plan–can also eliminate the fuel powered auxiliary power unit that is in the tail of most large commercial airplanes; replace with a electric hookup for ground use.

    Comment by MilesT | December 11, 2019 | Reply

    • I understand the points you are making, as I”ve flown a Cessna 340 at over 24,000 feet. I also have logged around a thousand hours on the type.

      I suspect that designing the aircraft as a whole with good insulation and efficient air con will solve the cabin problems. Winding-up may be more tricky and it could be innovative.

      Comment by AnonW | December 11, 2019 | Reply

  2. I’ve not heard much about Wright/easyJet recently, but Wright have just released a white paper discussing options for energy storage. https://www.weflywright.com/ shows their current plan is to adapt BAe 146s (remember them?) for 1-hr electric flights, converting engines one at a time 2023-6. Their map shows some of the flights this could handle, which should fit in with easyJet’s shorter schedules quite well. More on Wright’s progress on easyJet’s site https://mediacentre.easyjet.com/story/15210/easyjet-partner-wright-electric-successfully-tests-powerful-new-motor-and-announces-plans-for-dedicated-wright-lab-and-test-site-for-a-zero-emission-aircraft

    Meanwhile, easyJet reports https://mediacentre.easyjet.com/story/15265/ultra-low-emission-aircraft-turn-initiative-reduces-co2-emissions-by-97 that they’ve been trialling electric ground equipment at Bristol airport. The sooner this or something like it can be rolled out at all airports, the better.

    Comment by Peter Robins | November 4, 2021 | Reply


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