ELECTRO FLIGHT WORLD'S FASTEST ELECTRIC PLANE EXCLUSIVETHE STORY OF A VERY BRITISH PROJECT
Electroflight is an ambitious British project to create an electric aeroplane capable of 300 mph. #Drive-My
takes an in-depth look at the project and what it might mean for electric aviation. #Electroflight-Plane
Electric cars may soon become common place on our roads, but what about electric powered aircraft? Very much in its infancy, we take a look at a pioneering British electric plane project, that could herald potentially huge ramifications.
MAIN The Electroflight plane features a twin-prop design, with each being powered by separate motors.
Ever since the Wright brothers first took to the air, we humans have been obsessed with flight. Despite numerous efforts of varying madcap designs, the Wright brothers managed to successfully navigate a figure of eight course in the air ahead of anyone else in the world. Other attempt did actually result in flight, technically, but their efforts usually ended a bumpy landing and bruised pride, and those were the lucky ones.
Back then, nothing flew apart from paper aeroplanes that somehow managed to predate man’s first flight by many years. Despite these early difficulties, today anything designed seems to manage to fly. Take a look at the latest AirBus and it is a small wonder that such a giant, weighing hundreds of tonnes is able to take off at all - let alone that it has just two engines to propel it skyward.
From radial piston engines the age of jet planes just 40 years later, aircraft technology has advanced at a staggering rate. The first flight in 1903 was little faster than walking pace but by the late 1950’s planes were already capable of more than 3,000 mph. With all this very evident speed of progress, it is no wonder electric propulsion has never really had an opportunity to make a case for itself. But what could electric power bring to the world of aircraft?
An electric powered airplane has only just managed to cross the English Channel, while the Solar Impulse 2 is half way around its world tour in its bid to become the first electric powered aircraft to travel around the world. Both of these achievements were completed a hundred years ago in the history of flight, so what is the relevance today?
A small unit at an airfield in Gloucestershire might not be the headquarters of a huge multi-national conglomerate that you may have expected to front research into new and pioneering flight technology but it is the home to Targett Aviation, run by Roger Targett. Targett’s background is predominantly centred around making Red Bull air racer’s faster and sure enough, hidden beneath a dust cover is a current 200 bhp aerobatic display plane.
It’s a good starting point as Roger explains, “That plane there has the same power as the electric plane.” It’s a bold statement considering the size difference between the Red Bull air racer and the electric plane that sits nearby. “It’s quite disruptive technology as from a military point of view it has huge potential,” Roger continues as he delves further into the workshop lined with various different aircraft and gliders. There has been interest from various different fields and one perhaps less obvious than most is the military interest. Roger continues, “If you put me on the end of a runway with my electric aeroplane and I’m next to a frontline jet fighter like a Typhoon and we both hit the start button at the same time, I’ll be at 20,000 ft and climbing before they’ve even left the runway. They’ll soon catch up, but electric power is just so instant. A jet fighter takes about two minutes to spool up whereas electric is instant.”
It’s an interesting new perspective given to a benefit electric power might be able to provide over our pre conception that jet fighters are the quickest things in the sky. That they may well be, but it will take them a while to achieve that speed. Roger goes on to show us some electric concepts he created in response to a DARPA call for new drone designs. They’re a fascinating bunch of ideas but one thing is clear; with each speed and instantaneous response are the key advantages over a nav-gas powered alternative. Many of the solutions he presents exhibit some of the typical electric benefits we’re more used to on the ground but for very different applications. For example, zero emissions means an electric drone can be used inside a building or other mother-ship where they could be flown from. The lack of any liquid fuel means less risk of fire or explosion too. Naturally, there are drawbacks just as there are with most electric cars, namely batteries are heavy and therefore flying time is spoken of in minutes rather than hours. The solution, however, is simply to have more than one and charge those not being flown while the others are in flight.
Roger brings out another example. “In Afghanistan, they have to guard and maintain a two and a half mile long runway for drones and the like to operate from. An alternative is to have a ‘tail sitter’ electric powered drone that can launch vertically from a military base. It travels 300 mph and because it’s electric it has a tiny heat signature too and is relatively easy to hide from ground-to-air missiles. It takes about an hour to launch a Predator drone whereas electric doesn’t need any preparation time and is just instant,” says Roger. It’s a fascinating display of out-the- box thinking and a clever indication that electric propulsion could have actually found its niche, albeit in an unobvious solution.
Electric propulsion also has other possibilities with regards to other projects already in existence. The hybrid air-ship project currently being undertaken in Bedfordshire, for example, will initially be powered by diesel engines. However, air ships have a problem in that as fuel is burnt, the weight of the vehicle is reduced. As such, it is necessary to apply more energy when reducing altitude. Electric power would negate this factor as the weight of the batteries would not change.
Another factor where electric planes benefit over fuel power is cost. Roger explains, “The Rotax 912 is currently the most popular engine for sport and home built aircraft. To operate one of those for 2,000 hours, which is roughly the life of that engine before it needs a major overhaul, costs £96,000 in fuel, oil and other expenses. Equivalent power from an electric motor would cost as little as £12,000 to charge it and get a similar 2,000 hours use from it.”
However, as fantastic an idea as electric planes might be when up in the air, keeping them there could prove to be a problem not due to batteries or reliability but instead legislation. Roger adds, “With this project we would be writing the books for legislation and certification as it simply hasn’t been done yet.”
Aside from writing the rule book and possible military applications for electric aircraft propulsion, the plane you see on these pages has been built for aerobatic displays and outright speed. Capable of around 300 mph, the plane is powered by two YASA 400 electric motors, each providing about XX bhp. One motor sits behind the other and passes through the middle. The reason for this is that a twin contra-rotating propeller setup can be used, which gives additional benefits to manoeuvrability. Typically, when a single propeller is used, the plane can turn exceptionally well in one direction and less so in the other thanks to the gyroscopic effect created by the spinning propeller. The contra-rotating propeller overcomes this issue and also introduces new aerobatic possibilities not possible with a conventional aerobatic plane. For example, prop hanging is a common practice whereby the plane is controlled a bit like a helicopter with the whole thing hanging in the air on the power of the engine and the propeller. The effect to the audience is the plane is static in the air. Some pilots then like to show off a little and allow the torque of the engine to spin the plane around the propeller, known as ‘torque roll’. However, with a single prop this can only be done in one direction whereas with contra-rotating propellers, the same stunt can be done but in both directions. Thanks to the instantaneous torque potential from the electric motors, the climb rate can also be more dramatic and less progressive, with the possibility of evermore death-defying stunts being performed. The fuselage is built from a Nomex honeycomb sandwich covered in carbon-fibre and shares many similarities to other conventional aerobatic display plane designs. However, there are several key differences. Firstly, where fuel is usually stored in the wings, the batteries will be housed in the main fuselage. Secondly and most apparent is the nose cone. Because the electric motors are so tiny, it allows for the nose design to be as small as possible, rather than having a large frontal area. The result should mean improved aerodynamic performance and speed.
Unfortunately, as the plane you see here is only a demonstration model and not a flying example, it is difficult to say exactly how long flight time will be. Roger says, “I have a given volume of space for the batteries and when I first designed the plane that would have allowed for five minutes of flying, which is enough to do the speed record or a display at an air show. However, in the last five years since it was first designed battery energy density has improved to the extent that flight time could easily be doubled.”
The project differs from most other electric plane ventures because it is trying to achieve outright speed and performance to test the ability of electric power, rather than others who have tended to aim for endurance. Small electric motors with big batteries and huge wingspans seem to have been the preferred option over powerful electric motors with small batteries and high manoeuvrability. One of the possible uses, aside from aiming to break the electric air speed record at some 300 mph, is to have a fleet of these aircraft that could perform never before seen stunts and aerobatics in almost near silence too. There would, of course, be wind and aerodynamically induced noise but the motors themselves would be very quiet, especially when compared to noisy fuel powered aircraft at least. Roger adds, “The projected take-off weight is 420 kilos, including a 75 kilo pilot. 120 kilos of that is the batteries. The calculated thrust is about 500 kilos, so there’ll be 80 kilos of thrust in hand. Effectively, it will be able to go vertical. The Red Bull air racers can almost prop-hang, but not quite and it will roast their engine in the process. Whereas in the electric plane, it will be indifferent to this manoeuvre as, for a start, there won’t be much heat build-up. With the power to weight ratio in this, there’ll be nothing out there like it in its class.”
But, what sort of funding is needed to get a project like this off the ground? “Three million pounds,” Roger calmly exclaims. “We might be able to get matched funding through the various grant systems available, if we only achieve half of that but that’s to do it properly. It’s a big project to undertake because whereas others build only an air frame and buy an engine off the shelf from someone like Rolls Royce, we’re doing the air frame and propulsion system from scratch.” It’s a large amount of money, but in the grand scale of things if Electroflight are able to capitalise on their desire to be a world leader in electric aircraft propulsion it is a small price to pay when usually billions are spent developing a new car, for example. The money would go towards building three air frames initially, with the first being a test air frame to satisfy the authorities. This would be used for stress testing purposes, which would see it tested to destruction. The other two would be flying air frames with one built slightly more advanced than the other so that any necessary modifications can be incorporated into the other as they are built. Roger adds, “It would be great to also be able to build a few demonstrators and get them into air shows around the world to demonstrate their capabilities.” Ultimately, electric plane propulsion has more merits than may at first appear. It is now usual to hear about how an electric powered car outperforms a conventionally powered vehicle and the Tesla Model S is a good example of this. Electric aviation is in its infancy with only a few flying examples in existence around the world and while they may in their own right be pioneering projects, they have hardly attempted to push the envelope of possibilities. Electroflight is different in that their approach is more akin to that taken by Richard Noble who began the Thrust land speed record attempts. We all know that happy ending that rightly earned its place in history with worldwide acclaim. That project led to the current Bloodhound 1,000 mph land speed project, which is being used to invigorate an appetite in engineering for school children. It’s a worthy cause and a history that Electroflight could follow if they are able to obtain funding.
Being at the forefront of a new technology is not an easy place to be in as it requires a belief in something new and unproven. However, electric power is gaining acceptance in the car world and there is no reason why the same couldn’t happen for aircraft too. Whether Electroflight ever gets off the ground is likely a question of funding, but it certainly deserves to as it would put the UK at the forefront of an emerging technology that is bound to take off.
ABOVE A Tesla Model S gives the tiny electric plane some perspective. Cockpit is cramped but free from clutter. Same power, massive size difference. Advanced safety; Electroflight features a parachute for the plane, not pilot. / #Tesla-Model-S
Thrust 500 kgs
Max Speed 250 knots
Stall Speed 60 knots
Climb Rate 9.000 ft/min
Ceiling Height 25.000 ft
Batteries 120 kg Li-ion
Airframe (piloted) +/-10G
Weight (exc. pilot) 345 kgs
MAIN The Electroflight plane features a twin-prop design, with each being powered by separate motors.
AERODYNAMIC New and never before seen aerobatics will be possible from the near instant electric torque.
The plane in the background is a current Red Bull air racer with similar power, but the electric plane’s frontal area is significantly reduced allowing for better aerodynamics.
READY FOR RECORDS
The ambition by creator #Roger-Targett
(pictured) is to break electric records with this plane.