In the comments on niels nielsen's answer to "Why are no recent small aircraft designed to be 'characteristically incapable of spinning' as the Ercoupe was?," John K commented, "[The Ercoupe] doesn't glide any worse than its contemporaries. The procedure for losing altitude on final was to S turn."

niels nielsen replied, "handbook value for 65HP Piper J-3 is 10:1, 6:1 for the ercoupe..." From context, these seem to be glide ratios.

However, John K's reply us confusing to me: "Yeah but lots of contemporaries, biplanes, the short wing Pipers, also glide like bricks and you still have to side slip them from time to time, and if you had interconnected controls, you'd be left with S turns. 6:1 or 10:1 L/D is neither here nor there." He is mentioning the same ratios that niels nielsen did, but calling them L/D ratios, which I believe means lift-to-drag.

John's comment has three upvotes, so several people have seen it and not pointed out this apparent contradiction; because of that, I'm assuming there's something I'm missing. Doesn't this conflate two different ratios?

  • 1
    $\begingroup$ Just draw the angles. The amount of gravitation force extracted = Drag. The amount of Lift created by that Drag is in the L/D ratio. An aircraft with a higher L/D ratio has a shallower glide angle. One can decrease their L/D by slipping. Making S turns has a similar effect on the (linear) glide path. $\endgroup$ Dec 17, 2023 at 14:17


Browse other questions tagged .