Originally Posted by
john_tullamarine
Aerodynamically the correct glide Ratio is sink rate/IAS
Might we ask you to amplify this a little .. ?
I'm, afraid I need to, because after re-reading I see it can be a bit misleading/un-precise...
Lift and drag are dependent purely on IAS/CAS. The L/D will thus only be a function of IAS (leaving Mach aside). However, the distance travelled in a certain time will be greater when TAS > IAS. So while sinking at the same rate per second (Edit: Wrong assumption!), the distance travelled will be greater. The 'apparent' glide Ratio will be greater, while L/D still remained the same). So what I was trying to say is that with an L/D of 12 you might (Edit: not) achieve a glide Ratio of 16 to 17 regarding distance travelled from a defined Altitude.
Edit:
Please ignore this calculation. Thanks to @JT (I didn't read the signs and digged deeper, sorry!) and @Owain for pointing this out!