We always talked about a 12:1 glide ratio in the B-727-200. Who would care
about gliding with engines at idle, anyway?

In the T-33a, we were required to practice engine-out glides and approaches
down to short final. Engine-out performance was accomplished by setting the
throttle at 45% RPM and extending the speed brakes. With those settings,
the glide ratio was about 12:1, and the trick was to arrive over the numbers
on an upwind heading at 6,000 ft AGL, configure for landing, and perform a
360 deg spiral to short final where we'd initiate a go-around. Of course,
we'd modify heading/pattern entry point for winds and altitude.

IIRC, high key entry point for an engine-out F-106 was 18,000 ft AGL!


"Karl Kunz" wrote in message
...
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