DB601A Cruising Fuel Consumption

Discussion in 'Engines' started by krieghund, Dec 31, 2010.

  1. krieghund

    krieghund Member

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    #1 krieghund, Dec 31, 2010
    Last edited: Dec 31, 2010
    Does anyone have DB601A Cruising Fuel Consumption figures starting at ata 1,0 and below to about ata 0,76/0,75?

    I'm trying to work up a fuel consumption table for the DB601A series.

    Thanks in advance
     
  2. wells

    wells Member

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    Failing any manufacturer's data, it can be calculated to a reasonable degree of accuracy.

    0.08 g / L at 1.0 atm at 288 deg K ( 15 C sea level )
    stoichiometric ratio of 15 for octane ( C8H18 ) = auto lean mixture

    Displacement 33.9 L
    Multiply by Displacement * RPM * 0.03 for kg per hr
    For L per hr, divide by density of = 0.717 kg / L ( 6 lbs / US Gal, 7.2 lbs / Imp Gal )

    So, 1 atm at 2000 RPM would give 166 kg / h or 221 L / h

    The calculations can be compared to known data given in pilot's notes for various engines, to give some idea of accuracy. Here's some examples,

    I have for the DB605 from a British test of a 109G-2 Trop
    54.25 Imp Gal / hr at 1.0 ata and 2100 RPM at 18700 ft
    This is equivalent to 246 L/hr. At sea level in standard atmosphere, we have to reduce this figure to 214 L / hr to account for the higher ambient temperature for a given pressure ( air density is lower, see ideal gas law PV = nRT )

    The above calculation for the DB605 in this case ( 35.7 L ) gives 180 kg / hr or 251 L / hr
    This was probably a bad example, since I assumed 1 atm = 1 ata

    Using the proper conversion factor should improve the accuracy, which is left as an exercise for the reader. hehehe
     
  3. davebender

    davebender Well-Known Member

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    A while back Kurfurst presented some historical DB605 fuel consumption data. I believe it was in the discussion on best aircraft engines.
     
  4. Shortround6

    Shortround6 Well-Known Member

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    I don't have that information but at low power outputs the fuel consumption care vary considerably.
    Most people found that using low RPM and high boost (for the rpm) gave them the best fuel consumption IF the engine/propeller controls would allow it.
    For instance (if you are not already aware of it) there is a chart for the Merlin 45/46 that shows speed at altitude for various rpm and boost settings.
    I would assume (I Know :) ) that if two different settings give the same speed at the same altitude the engine is making the same power to the propeller.
    At 2000 ft and 200 IAS at -2.5lb and 2650 rpm the engine would use 35 gallons an hour but at -.5lbs and 1800rpm the engine used 31 gallons an hour.
    At 2000 ft and 230 IAS at +.5lbs and 2650rpm the engine used 40 g/h but at +2.75lb and 1800rpm it used 35 g/h.
    I don't know if the German controls (throttle and propeller pitch) allowed for such settings.
     
  5. krieghund

    krieghund Member

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    This is what I have gather via the internet on other forums but I have no source documents from the OEM stating these figures;
     

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  6. wells

    wells Member

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    Ugh,

    that top chart is a disaster, especially the last row at 6000 m

    445 IAS is 610 TAS ( 330 knots )TAS, not 515 ( I highly doubt 67 km/h instrument error ). Even then, I get 4.1 mpg, not 5.0.
    The other 3 rows look reasonable, except the IAS in the first row should be right around 300. Although, I suppose there could be 25 km/h instrument error? Seems like a lot
     
  7. krieghund

    krieghund Member

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    Yes that is my problem and why I am looking for OEM data. I think the airspeed at 6km should be about 495km not 515 as referenced in this table from an Airfix book on building the Bf109E.
     

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  8. davebender

    davebender Well-Known Member

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  9. Tzaw1

    Tzaw1 Member

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    From technical description of Bf-109E3, 1941.
     

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  10. krieghund

    krieghund Member

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    I just got this from Kurfurst
     

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  11. krieghund

    krieghund Member

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    I have done some math on the range table and found something interesting. In comparing the fuel usage without an external tank every altitude throttle/speed range consumes about 300 liters for the distance given which leaves 100 liters left for start-up, taxi and take-off with I guess reserves and a combat allowance.

    When calculating a table of fuel consumption per altitude with different throttle settings one must also include the fuel used to climb to that altitude and add the distanced climbed to the total distance traveled but usually let-down and and landing are not included in the distances.

    Because every altitude has the same amount of fuel remaining I have to assume that fuel to climb is not included.
     
  12. Tzaw1

    Tzaw1 Member

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    From Luftfahrt International 8/1975.
    Last records.
     

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  13. krieghund

    krieghund Member

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    Much thanks
     
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