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Thread: Consumption test

  1. #11
    Join Date
    Nov 2007
    Thanked 6 Times in 6 Posts

    Default Re: Consumption test

    Jim, Thanks. One would think that by the latter stages of the war some sort of template would have been drawn up which by including the bomb load and the profile of the track to be flown plus, perhaps, weather variables would have thrown up the fuel load required.
    Regards, Terry

  2. #12
    Join Date
    Jul 2013
    Thanked 47 Times in 47 Posts

    Default Re: Consumption test

    Just to add a little to Jim's impressive list of figures,the operational track miles per gallon (interesting subject) as with all TMPG figures is a continuously improving figure (ignoring aircraft problems and adverse winds),the fuel consumption of 4 large aero engines at max power must have been quite impressive and at a Large Bomb load All Up Weight (AUW) a high power setting on the engines would have been required for quite a while after take off,as fuel is used then the power setting can be gradually reduced whilst still maintaining cruise speed.Also at a high AUW the aircraft will be flying at a higher 'Angle of Attack' (nose up) which increases Drag and therefore requires more power to maintain cruise.

    Obviously there were variations of MPG even between aircraft of the same type/mark and whoever was tasked with producing a fuel consumption figure would fly different aircraft over standard routes/altitudes and thereby producing an 'Average' fuel consumption figure for that particular Mark of Aircraft.

    A little bit of RAF Deja vu appeared during the first 'Black Buck' Vulcan Bombing Raid,the Vulcan had never been tested for fuel consumption at such a high AUW (and thus - high AoA),the back room boys came up with a 'guesstimate' figure which subsequently turned out to be innaccurate (on the low side).Luckily the Tanker Boss on Ascension Island realised that all the tankers were returning earlier than planned (higher than calculated TMPG) and he sent out an extra tanker to meet the final Victor Tanker + the Vulcan,without the extra tanker neither of the a/c would have managed to return to Ascension.The Black Buck Raid was a real 'can do' attitude on a shoestring and with much thinking 'outside the box' to achieve it.
    Interestingly the Navigation and Bombing System (NBS) on the V Bombers was based around the H2S radar (+ Green Satin Doppler Radar +an analogue electro-mechanical computer called the Navigation and Bombing Computer),the NBS was used for the airfield attack using an offset initial point - quite an achievement for the Nav (radar) to actually get a bomb on the runway using such an archaic system.IIRC the Nav (plotter) did not even have a chart for the southern hemisphere so just turned a northern chart upside down :).

  3. #13
    Join Date
    Dec 2007
    Lions Bay, BC
    Thanked 25 Times in 21 Posts

    Default Re: Consumption test

    Thanks BVS for your thoughts. I'm not a pilot so have no knowledge on the subtilties on flying with loads. Just to emphasize what I provided below, are only "somewhat informed" estimates based on the data available. Any errors are unknown but the greatest "absolute percent error" is with the estimates of fuel remaining. All errors get transferred to, and magnified in that end result. It could easily be out by 50% or more. For example the estimated fuel remaining for Chemnitz (125 gallons) is quite low with very little margin for error given they landed at Middleton St. George, rather than a more southern diversion airfield.


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