Keep in mind the glide ratios you site are at idle thrust which is still significant. Engines out glide would be somewhere around 12:1.

-karl

On Monday, October 22, 2012 7:21:46 AM UTC-7, Papa3 wrote:
Most "normal" people would probably be surprised that modern airliners have pretty good glide performance. I have a table in some textbook that quotes values of around 17:1 to 19:1 for various models that were current in the 1980s when I was in school. This is about what the Schweizer 2-22 I learned in could do. These glide ratios are typically at about 200kts or a little more, so they sure do penetrate! And in fact, they do tend to have long, high-aspect ratio wings with winglets (more and more of them). But, given the huge range of speeds they need to fly, the requirement to store lots of fuel, handle very heavy wingloading, etc, there are a range of compromises required. Sweep angle for high mach numbers, accomodating tons of lift augmenting devices (slats, fowler flaps), fuel tanks, etc. are all things that glider manufacturers don't have to worry about.



On Monday, October 22, 2012 9:11:38 AM UTC-4, JohnDeRosa wrote:

I was asked last night "Why don't commercial airliners (747, A380,



etc) have 'super wings' like gliders?" I mumbled something semi-



coherent but didn't really know the correct answer.







So, would high aspect ratio and highly efficient glider-like wings



enhance fuel economy for all airplanes? What are the engineering



tradeoffs for wing design between a hulking airliner and a slim/trim



glider?







Sign me "I ain't no AeroE".







Thanks, John