title: Geiger HDP 10
text: # Geiger HDP 10
  
  The Geiger HDP 10 is a German electric motor for powering electric aircraft, designed and produced by Geiger Engineering of Seigendorf, Hirschaid, Oberfranken.
  
  ## Design and development
  
  The HDP 10 is a brushless 58 volt design producing 12.5 kW (17 hp) at 1950 rpm, with an outrunner coil. It has a 93% efficiency. The low working rpm of the engine means that it can turn a propeller at efficient speeds without the need for a reduction drive.
  
  ## Specifications (HDP 10)
  
  Data from Tacke
  
  ### General characteristics
  
  * Type: Brushless electric aircraft engine
  * Length: 171 mm (6.7 in)
  * Diameter: 215 mm (8.5 in)
  * Dry weight: 3.75 kg (8.3 lb)
  
  ### Components
  
  * Coil type: outrunner
  * Cooling system: air
  * Reduction gear: none
  
  ### Performance
  
  * Power output: 12.5 kW (17 hp) at 1950 rpm
  * Voltage: 58V nominal
  * Best efficiency: 93%
  * Power-to-weight ratio: 3.3 kW/kg
  