Raron is a small Alpine village in Switzerland. It is the place where celebrated poet Rainer Maria Rilke finally rested.
Just a few nautical miles away from this mythical place is the Swiss ex-Air Force base at Raron. The runway here is still being used by civil aircraft. The place is surrounded by steep mountains from north and south.
This place is also the birth place and home of an aerobatics aircraft, which is almost as silent as a whisper. This electric powered aircraft is a significant milestone in the Golden Age of quiet-aircraft development.
The aEro was launched at the Canton of Valais. Hamilton SEO Sylvain Dolla unveiled the concept on which Hamilton aEro is being built. This electric-powered aerobatic aircraft can carry single-seat and is fitted with a motor from Siemens.
This event is one of its kind. The financial support has been provided by the watchmaker and helped in realizing this novel project.
The credit for engineering this concept goes to Air Zermatt helicopter pilot Thomas Pfammatter, who has more than 10,000 hours of flying experience as a mountain rescue helicopter pilot and Dominique Steffen, who is a civil engineer and champion aerobatic para-glider pilot.
In short span of just eighteen months, the Hangar 55 company has been successful in developing and flying this wonderful, single-seat, electric-powered aircraft. The wings of this aircraft makes one remember the Super marine Spitfire.
Sebastien Demont, who was the chief of electrical systems on Bertrand Piccard’s Solar Impulse, provided with his electrical engineering expertise for the electrical interface and integration in the Hamilton Project.
The kit of the aircraft is designed and manufactured by brothers Thomas and Matthias Strieker (silence-aircraft.de). The aEro can be transported easily as it can be assembled and disassembled in just a few minutes.
The electric-powered aerobatic aEro opens up a completely new field of activity for aviators. Pilots can perform more rolls without losing any height and undertake less physical aerobatic style. The propellers run between 1,000 to 3,000 rpm by the electric motor.
The Technical Challenges
The roots of aviation are being rediscovered again with this electric-powered aircraft. This battery powered aircraft can only fly for a short duration, but engineers are working to improve the technology. The future holds out many promises.
The original name of this electric-powered aircraft was the Silence Twister and the silent flight it takes, it is named just right.
Before a take-off there is no need for noisy power checks, no magneto, and no need for engine warm-up time.
The batteries in the wing gets charged in 5 minutes and the ones behind the motor takes 20 minutes to charge. Work is being done to come out with a solution for plug-and-play.
This Swiss aircraft does not produce an ounce of CO2 and there is no whiff of avgas. Noise that reaches the ground observers is almost insignificant and muffled.
The MTOW of the aircraft is 925 pounds and the empty weight with batteries is 703 pounds. The three-blade, ground-adjustable, carbon and wood prop are made by Woodcomp. The weight of all the batteries is 352 pound and they are located behind the motor and in the wings.
The weight of the control unit and the motor is 29 pounds. The maximum endurance of the aircraft in around one hour at 92 knots, at present. In order to fly, the aircraft requires around 30 kW of energy. It can do aerobatics for around 20 minutes, along with two 10 minutes trip.
The aEro can roll at the rate of 270 degree per second, but the company is working to design a new type of wings that can give a roll rate of 400 degrees per second. Other developments that are being made include a sub-fuselage hidden pod for a thermally boosted battery charger for positioning lights.
The eAro use lithium batteries and demands for a complex electronic control system. Solar Impulse used only a small amount of current, but it run for many hours. Things are quite different in aerobatics, where lot of energy is required in a flick.
When a large current is needed, there is requirement to build a different type of electronics and communication using 108 battery cells. The batteries need to be managed in real time to fulfill lots of instant energy demand.
The big technical challenge ahead of engineers here is to deliver current at the rate of 200 amp / hr at 450 volts. The controls need to be programmed to respond less than a millisecond.
The electrical information has been translated in a form which a pilot can understand. Fuel level now become the energy remaining in current, volts, and inlet manifold pressure.
Another big technical problem was aligning the center of gravity as the electric motor is much lighter as compared to piston engine. Placing of batteries is important to provide good handling characteristics.
Batteries are placed in the wings as it produces less effect when compared to when they are placed somewhere else. No technical electrical problem has been found during inverted flight. However, the water-cooling system has some limitations.
The electric motor shaft from Siemens rotates at 11,000 rpm which turns the prop at around 2,900 rpm through a reduction gear. In aerobatic flight substantial lateral forces act on the prop. The reduction gear and the shaft ball bearing assembly have been designed and built specifically for this purpose.
The Future of Electric-powered Aircraft
Future pilots can enjoy flying and aerobatics at much lower cost with this technology and this aircraft. It will still take some years before a reliable technology can be accessed. Makers of eAro are confident that change will happen in less than five years.
When it happens electric-powered aircraft will overtake piston engine powered aircraft in aerobatics. Progress is being made at a great speed. Gas-powered engines will be replaced by electric motors, as they are not only very light and equally powerful.
Piston engine provide 35% energy efficiency, whereas electric-powered motors provide nearly 90% energy efficiency. The only factor that limits progress is battery technology.
At present, there are a number of limitations with electric-powered aerobatic aircraft. However, there are a number of advantages as well including noise reduction, reduced maintenance, low operating cost and energy efficiency.
Article and photo source: Plane&Pilot