Spirit of Innovation

Spirit of Innovation is an Electroflight designed propulsion system that they engineered and built into an airframe to set air speed records. Badged as the Rolls-Royce Spirit of Innovation.

  • 345 mph – 3 kilometres
  • 331 mph – 15 kilometres
  • 202 seconds – 3000 metre climb

Rolls-Royce ‘spirit of innovation’ is officially the world’s fastest all-electric aircraft.

The configuration of three motors powered by three battery packs was selected so that the aircraft can still fly safely if there is a problem with a motor. Another reason was that a single engine was not available for the power required. [1] The YASA motors can deliver a peak power of 250kW each.

The propulsion system weighs 700kg and the airframe weighs 300kg.

The battery pack was designed by Electro Flight.

Specifications:

  • total energy = 3 x 24.3kWh => 72.9kWh
    • made up of 3 battery packs for redundancy
  • module = 4.04kWh
  • usable energy = kWh
    • Usable SoC = %
  • peak discharge power = 400kW
  • nominal voltage = 648V
  • capacity = 3 x 37.44Ah => 112.32Ah
  • voltage range = 450V to 756V
  • weight [kg] = 475kg
    • module = 360kg
    • cells = 303kg
  • volume pack = 594 litres
  • pack dimensions = 1800 x 815 x 405mm (is this correct?)

Peak and continuous power: the cell used in this pack has a continuous discharge current capability of 30A, a C-rate of 10C. The battery pack has 72.9kWh total energy and at 400kW this would allow a runtime of approximately 10 minutes.

Based on a few cell parameters and the pack configuration we can calculate the voltage and current at the pack terminals:

  • cell resistance = 15mΩ [2]
  • at 100% SoC a power demand of 400kW
    • pack current = 562A
    • pack voltage = 714V
    • cell current ~15A
    • cell temperature increases ~10°C every 2 minutes
  • at 50% SoC a power demand of 400kW
    • pack current = 669A
    • pack voltage = 598V
    • cell current ~19A
    • cell temperature increases ~10°C every 90 seconds

These simple calculations show that this pack is easily capable of delivering 400kW. The cell resistance will actually decrease with increasing temperature, thus making voltage drops lower and hence lower current and heating.

  • number of cells = 6480
    • 180s
    • 3 x 12p (pack is designed as 3 sub-packs of 180s12p)

this page has been produced with the sponsorship and support of h.e.l group and TAE Power Solutions

  • charge time =
  • cells:
    • Format = 18650 cylindrical
    • Make and Model: Murata VTC6 (was Sony US18650 VTC6)

Multiple wire bonds: redundancy/current carrying?

Single sided busbars: negative connection is made on the top rolled over edge of the cell, positive connection made to the centre top cap.

  • modules:
    • total number of modules = 18 (6 in each pack)
    • nominal voltage = 108V
    • number of cells = 360
      • s = 30
      • p = 12
    • cell mass in module = 16.848kg
    • module mass = 20kg
  • cooling system = liquid cooled
    • centralised 3.9mm thick liquid cooling plate that is also a structural member all cells within the module were structurally bonded and thermally adhered to whilst remaining electrically isolated, this resulted in an impressively low distance between the cell and coolant of <1.5mm.
  • pack cost =

Key Pack Metrics:

  • Gravimetric energy density, pack = 155 Wh/kg
    • Cell = 240 Wh/kg
  • Volumetric energy density, pack = 125 Wh/litre
  • Gravimetric power density, pack = 842Wcont/kg
  • Volumetric power density, pack = 673Wcont/litre
  • Estimated cost = $/kWh
  • Cell to Pack mass ratio = 63.8%
    • module to pack mass ratio = 75.8%

Cell to Pack volume ratio = 18% This appears to be very wrong, I think the dimensions given for the pack are incorrect at 1800 x 815 x 405mm, but there is only one very poor quality image with this data.

Other key features:

  • Safety
    • 3 packs powering 3 motors to give redundancy
  • BMS
    • hardware = McLaren Applied Technologies [4]
  • HV Distribution
  • HV and LV Connections
  • Case material
  • Sealing strategy
  • Venting strategy
  • Durability
    • Aerospace DO-160G shock and vibration [4]
  • Availability
  • Recycling
  • Shipping

References

  1. Race for Power, Royal Aeronautical Society
  2. Sony VTC6 – a 3000mAh/30A monster in 18650 size, ThunderHeart Reviews
  3. Breaking Records with Rolls-Royce, DesignBoom
  4. How Rolls-Royce’s Spirit of Innovation broke the electric speed record, Aerospace Testing International
  5. Timothy Bingham, Mathew Moore, Taylor De Caux, Marco Pacino, Design, build, test and flight of the world’s fastest electric aircraft, IET Electrical Systems in Transportation, 2022

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