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News Release from: Saft Industrial Batteries | Subject: VL 41 M cells
Edited by the Engineeringtalk Editorial
Team on 06 November 2002
Lithium-ion cells boost aircraft
endurance
A switch to Saft high-energy rechargeable lithium-ion batteries will enable a revolutionary self-launching sailplane to reach an altitude of 3000m in powered flight.
A switch to Saft high-energy rechargeable lithium-ion batteries will enable Antares, the revolutionary self-launching sailplane with a retractable electric motor and propeller, to reach an altitude of 3000m in powered flight This is an improvement of around 1100m over the maximum height achievable by the prototype, powered by nickel metal hydride (Ni-MH) batteries
This article was originally published on Engineeringtalk on 21 Feb 2000 at 8.00am (UK)
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The Antares concept has been developed in Germany by Lange Flugzeugbau as the 'motorglider of the future' with a high performance, almost silent, and environmentally friendly propulsion system.
This consists of a brushless 42kW (56hp) electric motor with external rotor, power electronics, rechargeable batteries and a slowly revolving pusher propeller with a diameter of 2m.
For take-off and powered flight the motor and propeller unit is extended above the wing.
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For soaring the pilot simply pulls a lever and the complete propulsion unit retracts into the fuselage to improve the sailplane's aerodynamic efficiency.
The Antares prototype was designed around an Ni-MH battery system, which enabled it to climb under power to a height of around 1890m.
However, in the quest for even greater performance the design team decided to switch to Saft's VL lithium-ion cells, which were originally developed for hybrid and electric vehicle applications to pack as much power as possible into a lightweight and space efficient package.
These cells have a nominal capacity of 39Ah and a nominal voltage of 3.6V, enabling a significant increase in power for Antares from a battery that is 30% lighter.
The Antares battery system comprises 72 VL 41 M cells in series, providing a nominal voltage of 260V.
The total weight of the battery is around 76kg, which represents some 13% of Antares' maximum all-up weight (including pilot, parachute and water ballast) of 600kg.
Production versions of Antares will be limited to a maximum take-off power setting of 42kW.
This will provide an average climb-rate of 4.3m/s, enabling the motorglider to reach 1000m (twice the height achieved by a good winch launch) in under 4min.
The battery system can provide around 13min of duration at maximum power, which will take Antares to over 3000m.
Even in no lift conditions, from this height the motorglider will take an 100min to glide back to earth.
The Saft lithium-ion battery system is fitted with an electronic control management system for the monitoring of charge and discharge voltages, as well as temperature, and takes eight hours to charge at 220V.
A charger is fitted onboard the Antares to allow for cross-country travel.
The VL cells are capable of up to 1500 charge/discharge cycles, and in this application are expected to have a service life of around 11 years. Request a free brochure from Saft Industrial Batteries ...
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