Gloster Gladiator/ Bristol Mercury Engine

Discussion in 'The War In The Air' started by Adam Cotton, Sep 13, 2018.

  1. Adam Cotton

    Adam Cotton Member

    Hi all,

    I'm in search of information on the boost settings used on the Gloster Gladiator MKs 1 & 2, and associated RPMs. Does anyone know the maximum boost a Mercury VIII or IX engine could be operated at? And typical boost figures for cruising flight, and so on. Does anyone have access to pilot's notes or other official documentation?

    Any and all information gratefully received!

    Many thanks

  2. CL1

    CL1 116th LAA and 92nd (Loyals) LAA,Royal Artillery Patron

    hello Adam from profile publications
    for your interest


    • Power output:
      • 840 hp (625 kW) at 2,750 rpm at 14,000 ft (4,270 m) maximum power with 87-octane fuel
      • 995 hp (740 kW) at 2,750 rpm at 9,250 ft (2,820 m) maximum power with 100-octane fuel
    • Specific power: 0.65 hp/in³ (29.7 kW/L) with 100-octane fuel
    • Compression ratio: 7:1
    • Specific fuel consumption: 1.0 lb/(hp·h) (0.61 kg/(kW·h))
    • Power-to-weight ratio: 0.93 hp/lb (1.53 kW/kg)

    Bristol Engine Co: Mercury

    There are four engines in the Mercury series - the Mercury VIII and IX, and the Mercury XI and XII. All four have the same cubic capacity (24·8 litres) and the same cylinder diameter (51½ in). The Mercury VIII and IX are fully supercharged engines with an international rated power of 795-825 bhp at 13,000 feet, a take-off power of 730 bhp and a maximum power of 840 bhp for an all-out level flight of five minutes at 14,000 feet. The Mercury VIII has an airscrew reduction-drive ratio of 1 to 0·572 and weighs 995 lb; on the Mercury IX the gear ratio is 1 to 0·5 and this engine weighs 990 lb.

    The Mercury XI and XII engines, which in 1937 superseded the former Mercury engine, are moderately supercharged, having an international rated power of 790-820 bhp at 3,500 feet and a take-off power of 830 bhp. Their maximum power for all-out level flight (five minutes) is 890 bhp at 6,000 feet. In other ways the Mercury IX resembles the Mercury VIII, and the Mercury XII the Mercury XI.
    Bristol Pegasus and Mercury
    Last edited: Sep 13, 2018
    Chris C, Dave55 and Tricky Dicky like this.
  3. Adam Cotton

    Adam Cotton Member

    Many thanks! Much appreciated!

Share This Page