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Thread: DCS Spitfire Economical Flying

  1. #1

    Default DCS Spitfire Economical Flying

    In the text below I have transcribed the notes from Jarrod Cotter's book "Flying the Icon : Spitfire" regarding economical flying for the Spitfire LF MkIX with the Merlin 66 (the Spitfire modeled in DCS). Before getting to the economical flying section, it is interesting to have the maximum performance figures.

    QUOTE
    Maximum performance Spitfire MkIX Merlin 66
    (i) Climbing
    The speeds (mph IAS) for maximum rate of climb are:
    Sea level - 26,000 ft 160
    26,000 - 30,000 ft 150
    30,000 - 33,000 ft 140
    33,000 - 37,000 ft 130
    37,000 - 40,000 ft 120
    Above 40,000 ft 100

    With the supercharger switch at AUTO, high gear is engaged automatically when the aircraft reaches a predetermined height. This is the optimum height for the gear change if full combat power is being used, but if normal climbing power (2,850 rpm +12 lb/in2 boost) is being used the maximum rate of climb is obtained by delaying the gear change until the boost in low gear has fallen to 8 lb/in2. This is achieved by leaving the supercharger switch at MS until the boost has fallen to this figure.

    (ii) Combat
    Set the supercharger switch to AUTO and open the throttle fully.
    NOTE: On those aircraft which do not have interconnected throttle and propeller controls (DCS LF MkIX Spitfire) the propeller speed control lever must be advanced to the maximum rpm position before the throttle is opened fully

    Economical flying
    Climbing
    On aircraft not fitted with interconnected throttle and propeller controls (DCS LFMkIX Spitfire).
    Set the supercharger switch to MS, the propeller speed control lever to give 2,650 rpm and climb at the speeds given above, opening the throttle progressively to maintain a boost pressure of +7 lb/in2.
    Set the supercharger switch to AUTO when the maximum obtainable boost in low gear is +3 lb/in2, throttling back to prevent overboosting as the change to high gear is made.
    NOTE: Climbing at the speeds given above will ensure greatest range, but for ease of control (especially at heavy loads) a climbing speed of 180 mph IAS from sea level to operating height is recommended. The loss of range will be only slight.

    (ii) Cruising
    The recommended speed for maximum range is 170 mph (155 kts) IAS if the aircraft is lightly loaded. At heavy loads, this speed can be increased to 200 mph (172 kts) IAS without incurring a serious loss of range.
    On aircraft not fitted with interconnected throttle and propeller controls:
    With the supercharger switch at MS fly at the maximum obtainable boost (not exceeding 7 lb/in2) and obtain the recommended speed by reducing rpm as required.
    NOTE: (i) Rpm should not be reduced below a minimum of 1,800. At low altitudes, therefore, it may be necessary to reduce boost or the recommended speed will be exceeded.
    (ii) As the boost falls at high altitudes it will not be possible to maintain the recommended speed in low gear, even at maximum continuous rpm and full throttle. It will then be necessary to set the supercharger switch to AUTO. Boost will thus be restored and it will be possible to reduce rpm again (as outlined in (a) above)
    UNQUOTE

    I now need to check if these figures are accurately modeled in the DCS Spitfire flight model.
    Note that with low rpm there is a danger of the engine getting too cold.
    "Sit and spin the fire". Extract from Topsy Turvey Land, a poem by William Brighty Rands.
    "In the bar everyone knows what they should have done - the problem is in applying it in the heat of the action". F Barthe RIP

  2. #2
    W/C of 51° Stormo, T/O Jimmi EAF51's Avatar
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    Default Re: DCS Spitfire Economical Flying

    Nice reading Topsy!

    start checking here!
    http://www.stormofwar.org/phpBB3/vie...umption#p53181



    VEF - Bellum- Seow Marianes - Seow Crete - Seow Stalingrad -Seow Med MultiSector NE Africa/Nw Malta - SOW I II III & IV
    155º Gruppo 51º Stormo
    We will intercept them, shoot them down and drink some grappa afterwards! Woah!

  3. #3

    Default Re: DCS Spitfire Economical Flying

    My first reaction is that D Fenir's economy reference speeds @ 1800 rpm are all higher than the recommended 170 mph IAS in clean configuration. His range from 190-220. When I get time I will check endurance at the recommended setting and see what it gives in DCS.
    "Sit and spin the fire". Extract from Topsy Turvey Land, a poem by William Brighty Rands.
    "In the bar everyone knows what they should have done - the problem is in applying it in the heat of the action". F Barthe RIP

  4. #4
    W/C of 51° Stormo, T/O Jimmi EAF51's Avatar
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    2004-11-19
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    Default Re: DCS Spitfire Economical Flying

    Quote Originally Posted by EAF79_Topsy View Post
    My first reaction is that D Fenir's economy reference speeds @ 1800 rpm are all higher than the recommended 170 mph IAS in clean configuration. His range from 190-220. When I get time I will check endurance at the recommended setting and see what it gives in DCS.
    yeah consider you are using real data while he's testing DCS data! Some difference is to be expected!


    VEF - Bellum- Seow Marianes - Seow Crete - Seow Stalingrad -Seow Med MultiSector NE Africa/Nw Malta - SOW I II III & IV
    155º Gruppo 51º Stormo
    We will intercept them, shoot them down and drink some grappa afterwards! Woah!

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