I'm looking for L/D ratio of old warbirds. I'm particularly interested by the P-51D, the Supermarine Spitfire Mk.VII and the Mitsubishi A6M3 Zero, but I'm also quite curious about other warbirds that flew during this period.

What are L/D ratio of those warbird? The answer may include L/D ratio of other WWII fighters.

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    $\begingroup$ Interestingly, resource location questions are usually off-topic, but this can be made on-topic by steering away from "where can I find..." and instead asking "what are the..." which will no doubt bag you some references. $\endgroup$ – Jamiec Dec 11 '19 at 16:25
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    $\begingroup$ @Jamiec: I agree, many times I changed "where" to "what". More interestingly, it's because instead of a "bam <URL>" that may expire or "bam amazon link" that is of no help to a wider audience, asking directly for the problem is better. Even better, asking for why/how, e.g.: How does the modern L/D ratio compare to WW2 planes and what led to the improvements, if any? $\endgroup$ – ymb1 Dec 11 '19 at 20:04
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    $\begingroup$ @jamiec edited accordingly $\endgroup$ – Manu H Dec 12 '19 at 6:36
  • $\begingroup$ Is a meaningful answer possible for aircraft that fly at a wide range of speeds and g-loads? For steady level flight, lift will equal weight and drag will equal thrust, but the drag/thrust will vary hugely between approach speed and max speed. Should we limit this to optimum glide angle, or some definition of 'cruise'? $\endgroup$ – Robin Bennett Dec 12 '19 at 13:20
  • $\begingroup$ Not a real answer, but you could try www.wwiiaircraftperformance.org it doesn't have the L/D ratios on the site itself but contains links to technical reports on the aircraft that may have that information $\endgroup$ – Dave Gremlin Dec 12 '19 at 14:04

Please find the answers below from "World war II fighter aerodynamics" by David Lednicer.

And L/D, of course, depends on the CL you are flying at but you can easily calculate it from the unambiguous drag area given

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Edit: Calculated L/D vs speed curves below for 4000m altitude flight. A fixed span efficiency was taken to simplify the calculation. Please consider this as an approximation only

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  • $\begingroup$ +1 for the link to the paper, very entertaining. $\endgroup$ – Koyovis Feb 8 at 0:53
  • $\begingroup$ How would one calculate the L/D from a given drag at unknown conditions, since both CL and CD are functions primarily of aoa. $\endgroup$ – hph304j Feb 8 at 17:34
  • $\begingroup$ I've attached a calculated polar for clarity. It's not hard to calculate these ones you got the basic aircraft geometric information such as AR, Wing Area, etc. Calculated L/D is for 4000m altitude flight $\endgroup$ – user46017 Feb 10 at 2:56

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