The Anonymous Widower

Alice Promises Passengers A Pollution-Free Wonderland

The title of this post is the same as that of this article in The Times.

The Eviation Alice is a composite battery-electric aircraft, that has just been ordered by Cape-Air, who are based in Barnstaple, Massachusetts..

Currently, Cape-Air flies the following fleet of aircraft.

• Eighty-eight Cessna 402, which seat nine passengers.
• Four Britten-Norman Islanders, which seat nine passengers.

In addition, a hundred Tecnam P2012 Traveller are on order, which seat nine passengers.They will replace the Cessnas.

The specification of the Tecnam P2012 Traveller, was developed with input from Cape-Air,

• Two Avco Lycoming piston engines.
• 190 knot cruising speed.
• Range of 950 nautical miles
• Full certification.
• Large passenger door.
• Suitable for commuter, air taxi, medevac, troop transport and air cargo roles.
• iSingle-pilot operations, a modern cockpit, an unpressurised cabin and a metal air-frame.
• High -wing for visibility
• Fixed landing gear for operation from rough landing strips.

It appears the Italians have designed a modern Islander.

This leads me to the impression, that the commuter airline operator are experienced, conservative and know what they want.

On the other hand, Cape-Air have just ordered ten Eviation Alice aircraft for air-taxi operations.

• Nine passengers and two crew
• Three 260 kW electric motors
• 900 kWh Li-ion battery
• 260 knot cruising speed.
• Range of 565 nautical miles.
• 95% composite air-frame.
• Fly-by-wire control
• Unpressurised cabin.
• Retractable landing gear.
• Automatic landing.

It is not a conventional aircraft.

If you want to learn more, this article on Aviation International News, which is entitled Eviation’s Alice To Fly This Year, gives a lot more details.

These are a few points.

Aerodynamic Design

It is to be expected,  that the composite structure has created a very aserodynamic design.

Battery Weight

The battery comprises sixty per cent of the weight of the aircraft.

Battery Charging

The Aviation International News article says this about charging.

The battery system on the Alice will be fully rechargeable in one hour and 10 minutes, using a half-megawatt charger on a mobile “bowser” truck that itself is charged up by plugging into the local electrical grid. This avoids having to build charging stations at airports, he said. Not all routes will require a full charge—the basic ratio is a half hour of charging time per hour of flight.

Given the 1:2 ratio between charging time and flight time, I suspect that Eviation are using similar tricks to those used by Vivarail with battery trains, that I wrote about in Vivarail Unveils Fast Charging System For Class 230 Battery Trains.

Landing Gear

Once the passengers and their luggage are on board, the weight of an electric plane will not change until the passengers disembark.

I suspect this gives advantages in the design of the landing gear, as it probably cycles through a narrower range of stresses, than the gear on a conventionally-powered plane.

Engine Failure

Engine failure in a twin-engined aircraft is every pilot’s nightmare and speaking from experience, there is no better moment in a flight in a piston-engined twin, than when the gear is raised and the plane is safely in the climb.

The Aviation International News article says this about controlling engine failures.

If power is lost in one wingtip-motor, the opposite motor will reduce power to prevent asymmetric thrust from causing a loss of control, while the rear motor can provide enough power to keep the Alice flying. In fact, Alice can continue a takeoff with loss of both tip thrusters at V2, according to Bar-Yohay.

This is how computer control should be used.

Take-Off And Landing Distance

The specification foe the Eiviation Alice,  does not give the take-off and landing distances, but it does give the approach speed as 100 knots.

The Eiviation Alice is replacing Cessna 401 aircraft at Cape-Air, so it must have a better performance.

The figures for the Cessna are.

• Tajke-Off Distance – 520 metres
• Balanced Field Length – 700 metres
• Landing Distance – 250 metres

Until, I’m told otherwise, I suspect that the Eviation Alice could use most seven-hundred metre runways, with a good surface.

Take Off Accidents

A lot of air accidents happen on take-off, when the plane is fully loaded with passengers and fuel and the engines are giving out maximum power. If the plane should crash, there is usually a large fire.

There have been fires in lithium=ion batteries in the past, but you don’t hear of hundreds of electric cars going up in smoke.

I would certainly like to see what Eviation are saying about the performance of Alice aircraft in an abandoned take-off, or one where an aircraft hits something large, that shouldn’t be there,  on the runway,. Thankfully, the latter doesn’t happen often, but read about the Tenerife Airport Disaster in 1977.

Fly-By-Wire

Fly-by-wire would not normally be expected on an aircraft of this size. But the Aviation Internation News article says the following.

• The propellers can be managed using pitch and rpm to reduce noise.
• Turbulence can be smoothed out.
• Differential thrust can be applied to the two wing engines for crosswind landings.
• The battery system can be fully controlled in sixteen strands to bring a high level of redundancy.
• Autoland can be added.

This is a commuter aircraft with all the flight control features of a full size airliner, that has been designed to be flown by a dumb well-programmed computer.

Those that have designed advanced fighter aircraft would certainly approve.

Happy Landings

In the Wikpedia entry for the Eviation Alice, this is said.

It will be built with existing technology, including a composite airframe, distributed propulsion with Siemens electric engines and Honeywell flight control systems, including automatic landing.

The approach speed is also stated on the plane’s specification to be a very reasonable and pilot-friendly; 100 knots.

Once, I flew an approach in a Piper Arrow into Dublin Airport faster than 100 knots as Air Traffic Control, said there was a Jumbo on my tail and could I hurry up! They then asked if I could clear the runway fast, which I did, to be greeted by “We’ll give you ten out of ten for that!” The Irish are gloriously different!

Under Fly-By-Wire, I said this was possible.

Differential thrust can be applied to the two wing engines for crosswind landings.

This I like, as I was not good at crosswind landings.

Once, I landed my Cessna 340 in very heavy rain and strong crosswinds at Cardiff Airport. I landed safely, but it was lucky I was wearing appropriately-coloured underwear.

Cost Of Ownership And Operation

The Aviation International News article gives full details.

The Future

The one thing that can be said about the design of electric planes, is that the batteries will hold more power for a given weight in a few years.

In addition.

• Composite structures will get lighter and stronger.
• Aerodynamics of the air-frame and the propellers will get better and more efficient.
• Fly-by-wire will use better algorithms and add more features.

Range and/or payload will increase.

I also think that, if they can be almost silent, then they could fly very different routes and perhaps even use runways reserved for electric aircraft.

Conclusion

This project might appear to be a total fantasy, but having flown over a thousand hours in a small twin-engined aircraft, I can see where Eviation are coming from.

• They have also convinced Cape-Air, top class suppliers like BendixKing, Hartzell, Honeywell and Siemens to be part of the project.
• If nothing else, Eviation have proven, that they can design and build a nine-seat commuter aircraft.

I feel, I can look forward one day to flying in an electric aircraft. Even if it is not the Eviation Alice.

Aircraft like Alice will revolutionise aviation, for distances up to perhaps two thousand miles.

June 19, 2019 - Posted by AnonW | Energy Storage, Transport/Travel | Electric Aircraft, Eviation Alice, Flying