## Wright Electric to develop electric 100-passenger aircraft for one-hour regional flights

##### 05 November 2021

Wright Electric, Inc. (earlier post) is adding a new member to its planned family of zero-emissions aircraft for the commercial market—the Wright Spirit will incorporate Wright’s megawatt-class electric propulsion system and serve the 100-passenger market for one-hour flights.

The Wright Spirit aircraft design builds on the BAe 146 platform—a 100 passenger, 4-engine aircraft known for its operation out of noise-sensitive airports. The existing BAe 146 hydrocarbon-based propulsion system will be replaced with Wright’s all-electric, emissions-free propulsion system.

The path was set in early 2020 with Wright’s announcement and development of a megawatt propulsion system for an all-electric commercial aircraft. Throughout the last two years, the company has been proving key components of the system including a high-efficiency, high-power density inverter and a 2 MW (2,700 HP) motor.

By focusing on one-hour flights, the Wright Spirit addresses the world’s busiest city pairs, such as Seoul-Jeju (world’s busiest route, 14 million passengers annually), London-Paris, Rio de Janeiro-São Paulo, and San Francisco-Los Angeles.

To develop the integrated propulsion system, Wright has assembled a team of companies with expertise in generation, energy storage and propulsion design. The program now proceeds with on-going ground testing and final selection of the propulsion system. In 2023, the aircraft will begin flight testing with one all-electric propulsor. The development program will then accelerate towards flight testing with two all-electric propulsors by 2024 leading to the full-electric aircraft by 2026.

I have been floating an idea on this recently. Can they make a hybrid electric/hydrogen turbine for the engines? Burn hydrogen in the turbine portion in addition to electric motor for take off. Once at cruise shut down the fuel burning turbine and let the electric motor spin the turbofan by itself.

Anyone know the comparison between energy density of battery vs H2 storage on a kg basis? BTUs or Joules per kg?

Any word on the battery size and composition? Commuter planes are expected to get back in the air as quickly as possible.

@Jason Burr

They did not explicitly say where the electric power was coming from but as it is for short flights lasting about 1 hour, I assume that it battery electric. The main reasons for using battery electric are the high energy efficiency and the low cost of operation. They are going to modify an existing aircraft but eventually you would want to build a more efficient airframe. Also, another problem with battery electric is that the landing weight is the same as the takeoff weight while, with long distance aircraft, considerable weight of fuel is burned off during the flight.

Anyway, if I did the math correctly, there is about 141 MegaJoules/kg or about 39 kWhr/kg of energy available with hydrogen (started with 286 kJ/mole of the oxidation of H2). (I really wish we would use Joules instead of kWhr). Currently, lithium-ion batteries have about 250 Whr/kg or about 900 kJ/kg but this will probably be up to 400 Whr/kg or 1.44 mJ/kg by the time they are flying and maybe up to 600 Whr/kg or 2.16 mJ/kg or more if we have working lithium sulfur batteries. So, you could argue that hydrogen has about 100 times the energy density but it is not that easy as you need to add in efficiency of the engines or fuel cells and the weight of the tanks or pressure vessels. Realistically is probably closer to 25 or 30 to 1. But, again, while the batteries are considerably heavier, the real advantage of battery electric is the low cost of operation.

JB good idea LH2 would do it

Here is the site:

https://www.weflywright.com/

And in the WP they say that the two energy systems they are considering are hydrogen and aluminum fuel cells.

Batteries can't do anything remotely like even an hour for this size of plane.

And 1 hour is really 2 hours. Scheduled airlines fly under IFR rules, which amount (in most places) to having another hour's reserve endurance.

Davemart

Are they aluminum fuel cells or aluminum air batteries? Wikipedia has them as primary (non-rechargeable) batteries and Wright's energy storage paper has a note that they can also be considered as batteries. The problem is that the aluminum anodes are used up and need to be replaced and the electrolyte needs to be recycled to recover the aluminum. I do not think that this is going to happen but this is my opinion based on economics.

Also, your comment on the size of plane vs range is backwards. It is easier to get longer range with a larger aircraft but it is, of course, much more expensive to build larger prototype aircraft.

In the Argonne Lab paper, Assessment of R&D Needs for Electric Aviation_FINAL.pdf , they conclude that you need about 500 Whr/kg for a regional jet type aircraft and at least 800 Whr/kg for a 737 class aircraft.
See https://anl.app.box.com/s/xr1wk53shzhvu4w3l57j90t1mhkq01b5

We will have to wait and see how successful Lyten and maybe Monash or others are with Lithium Sulfur. Anyway, I would bet on Lithium Sulfur before Aluminum Air. Lyten is projecting 900 Whr/kg with production in 2025/2026 but it is not lost on me that Oxis was also making great projections before they went bankrupt.

@sd:

When I saw that they were talking about aluminum air batteries I stopped reading, as they are AFAIK nowhere near production ready.
I did skim down to where they indicated that they are pushing the envelope for conventional hydrogen fuel cells though, which does not in my view greatly enhance their cred.

I have no idea why you take objection to my comment about range, as range and payload are the two factors which determine the need for storage and what will work and what won't, with actual practical battery electric aircraft, which I fully support, of course more limited in both than fuel cells.

Perhaps you could read the WP which I have linked and then comment instead of criticizing my take, which is at least based on information which I took the trouble to dig out, which took all of ten minutes.

Instead of doing so yourself you went off on wildly speculative stuff about batteries doing the job.

Batteries are great, providing their limitations are respected and they are not treated as a panacea.

S/be 'aluminum fuel cells' not batteries.

Davemart

I read about the first 1 1/2 pages of the WP last night as I could not get it to completely load. This morning, I found I could reload every page or so and read all of it. Anyway, Wright is designing and building high power electric drives for aircraft propulsion. I think that Wright is relatively agnostic as to how the electric power is stored or generated. One problem with aluminum air (fuel cells or batteries, I do not care) that I had not considered is that the aluminum is going to aluminum oxide which is stored in the electrolyte so the weight is going up as you fly. Anyway, they also acknowledged that you would need to build a different design aircraft to make efficient use of the electric drives but they are trying to use an existing airframe to test their motors and inverters.

Wright also noted that you needed at least 750 Whr/kg for their aircraft which is about the same as the 800 Whr/kg as I had from the Argonne paper. They seem to favor aluminum air as they seem to think that it would less expensive compared to hydrogen but, again, they are not in the energy storage business. They did note that lithium ion would not work but did mention that lithium sulfur on page 12 as a possibility. "Note that both hydrogen and aluminum fuel cells easily exceed the 750 whr/kg barrier and Li-S is the only traditional battery chemistry with the possibility of doing so."

As to my comment on range vs size, it is easier to build a larger airplane with greater range than a smaller airplane with greater range using the same technology and that is true whether you using jet fuel, hydrogen, batteries, rubber bands or whatever.

Again, the reason why I think that lithium sulfur will eventually win for short range or regional aircraft is economics. Bye Aerospace is projecting that their battery electric 8 seat commuter aircraft will cost about 1/4 that of a conventional turbo-prop on a seat mile basis. It is simply cheaper and more energy efficient to recharge batteries. I currently drive a Chevy Bolt and with 44,000 miles of driving have averaged 4.3 miles/kWhr and pay $0.11 per kWhr so the cost per mile is about$0.025 or 2.5 cents. There is no way that I can run a gasoline, diesel, or even a fuel cell vehicle for that cost.

Davemart

Maybe I can better explain some of the scaling that affects the range and size of an aircraft. It mostly has to do with power laws. If you take a small airplane and make it larger, the volume would be cubed while the frontal area and the total skin area would be squared. Some of the drag comes from the frontal area and the total skin area. Some of the drag is induced drag that comes from developing lift to overcome the weight. If you kept every thing the same while scaling up the plane, the weight would also be cubed. However, if you model the structure as a tube which it more or less is and the wings can be though of as a airfoil shaped tube, the stiffness of the structure goes as the fourth power of the scaling so you can also cut down on the structural weight. Cutting down on the weight cuts down on the induced drag. Anyway, you should be able to see where this is going. The drag does not go up as much as the size so it is easier to build a larger plane with greater range.

The Wright Spirit aircraft design Is a total waste. It cannot compete with the best 100 seat aircraft today, the Airbus A220-300 (formerly Bombardier CS300) which uses geared turbofan engines. When these aircraft convert to Sustainable Aviation Fuel (SAF) by 2030 who needs batteries or H2 (check out Engineer-Poet’s suggestion in “Man Gas Engines enable hydrogen use . . “, on how to make a lot of SAF. https://www.greencarcongress.com/2021/11/20211105-man.html
Batteries and/or H2 would be OK for eVTOL though (particularly the “quiet” Joby maybe with 2 fewer rotors).

SD
Good explanation

@sd

I'm pretty much up to speed with who is trying what for what range and payload in aircraft thanks.

And much more importantly so are the various manufacturers, who AFAIK are united in not considering batteries for anything remotely approaching that size, range and payload.

When we have some magic chemistry no doubt that may change.

How on earth you could imagine that they would be considering batteries as the main storage source for this application baffles me, and perhaps since your notion is utterly mistaken you might look into your assumptions a little more thoroughly instead of outlining the assumptions which presumably have so misled you.

In any case these guys are clearly way out in left field with their notions of aluminum fuel cells, which are nowhere near commercial production.

Perhaps they should just stick to magic batteries.

Davemart,

Every year for the past 13 years except for 2020, I have attended the EAA (Experimental Aircraft Association) Airshow in Oshkosh, Wisconsin. Having an interest in technology in general and electric power, I have talked to many of the major players in the field including Pipistrel, Bye Aerospace, and Airbus. Pipistrel has a 2-seat battery electric trainer that is European certified. I think that their specs are a bit marginal with a 1 hour plus 30 minute VFR reserve range but they are up and flying. Bye has a 2-seat trainer prototype that is flying and is working on certification. They are claiming a 220 Nautical Mile Range with 260 kWhr/kg lithium ion batteries with a more reasonable payload. They are also building a 4 seat prototype with a 260 nm range at max payload. They claim over 700 deposits for the 2 and 4 place planes. Bye is also working on an 8 seat plane but maybe that is waiting for what you call magic chemistry batteries. Airbus had a non-working 4? place prototype 2 years ago and pictures of larger regional aircraft.

This is going to happen simply because of the economics. Pipistrel claims a 1 Euro cost of power for a 1 hour flight plus no oil changes and very minimal maintenance.
It is just plain economics. It will take a few years for larger regional aircraft but the economics are just too great to ignore.

The prospects of a new 100 seat aircraft before 2035 is close to zero.
That said we can/should look at efficient electric transport for short distance flights below 500 km, e.g. New York to Wash DC or London to Paris., this is a significant percentage of all air travel.
A 2 hour range is all that is required. (1.5 hours flight time plus VFR reserve) and eVTOL will provide door to door travel. My new favorite eVTOL is the Overair (formerly Karem) Butterly (check: https://overair.com/product/). As I stated earlier 4 rotors is all that is needed. The Bell Nexus is another example. Five to Six passengers is the best size also.
The Overair Butterly will be battery only, however, you could go with H2 Fuel Cells if you take the best example - the Hyundai Vision FK, 2 670 hp, 200 kW FC, and large battery built by Rimac (https://www.motortrend.com/news/hyundai-vision-fk-concept-first-look-review/). Overair already has a Korean partner Hanwha Systems so maybe another may help.

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