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#1
01-12-2012, 01:36 AM
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But this is the whole point. For me E-Liability is the capacity of a plane to retain energy which is the sum of speed-based energy and altitude-based energy. I do not want to go into detail but basically E-Liability in a turn for instance will depend on the lift a plane can generate by increasing the angle of attack and how much this will cause drag. The more you pull the more lift your plane generates due to higher angle of attack and the tighter you turn. Now basically ALL planes will be able to generate the same amount of lift or let's say the same amount of lift/weight. A plane however that requires more angle of attack to do so will create - by same aerodynamic performance - more drag than one that does not need this. For instance this would happen to a Spit that has a higher weight. In order to achieve same turn radius the heavier Spit would require higher angle of attack and hence more drag would be created slowing down the heavier Spit more.
Again, if the aerodynamic performance is not as well for a plane (at same weight) it would either also have to pull more angle of attack to create the same amount of lift. Or, even if another not so performing plane can generate same amount of lift with same angle of attack, it still might generate more drag. Now if we take into account propulsion too, we can basically say that the plane with the better thrust will be more at ease to compensate higher drag, so even if the plane would have to pull stronger for same turn radius (for instance because of higher weight, aerodynamic performance being similar otherwise) it might still be capable to preserve its speed at the same rate as the lighter aircraft if its engine is powerful enough. So, summa summarum, it is a darn complicated story. My guess is that no flight sim ever gets so deep into detail to really come up with a good set of data. I think all flight sim FMs are based on some parameters and tweeks to fit quantitave and some qualitative criteria for each plane and hoping that for other qualitative criteria the outcome is ok. 
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#2
01-12-2012, 01:40 AM
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#3
01-12-2012, 02:05 AM
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Specific Excess Power (Ps) is the measure of cough "E-Liabilty", and takes into account the complete picture, i.e aerodynamics power etc. The Fan plot in Il2 Compare provides a single Ps=0 line at 1000m for all types derived from turn times. From this you can determine each types Sustained G capability which is a function Ps. Fan plots were invented for this purpose.
We also know of the calculated Fan plot that the RAE produced for the 109E3 and Spitfire I at 12,000ft. Comparing the values will provide a comparative measure of Sustained turn performance ... or E under G/AOA. The chart gives the 109E 3 a sustained turn capability of 2.4G and the Spitfire MKI a sustained G of 3G. A 0.6G sustained turn advantage is pretty significant Neat On line implementation of Il2 Compare whose responsible for that ? V101_Tom or Ace of Aces ? ... be nice to see the fan plots in there as well. Last edited by IvanK; 01-12-2012 at 02:18 AM.
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#4
01-12-2012, 02:38 AM
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See the link to the pdf in my previous post.. I have fan plots (aka DogHouse) and Ps charts and more.. I am slowly adding those each weekend that I get some time to work on it.. I actully have the fan plots done, but, I need to add the lables for the constant load factors and constant turn radius lines.. I have done all this before in MATLAB, but never before in a website app in C#, but it is not hard to do, just takes time. My goal is to have everthing that is in that pdf on my webpage.. AND MORE!  For example, you can change the fuel loads in my version of IL-2Compare Online, which is something you could not do in the old executable version
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Theres a reason for instrumenting a plane for test..
That being a pilots's 'perception' of what is going on can be very different from what is 'actually' going on.
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