×
Welcome to the CPL Aerodynamics question and answer forum. Please feel free to post your questions but more importantly also suggest answers for your forum colleagues. Bob himself or one of the other tutors will get to your question as soon as we can.
The efficiency of a wing is decided by the angle of attack, not the speed.
If you want the best glide performance, there is only one angle of attack that will give it to you.
That angle of attack will produce the best lift/drag ratio.
The speed to use at that angle of attack is determined by the aircraft weight. If you are heavy, you will need more speed with that angle of attack to get the extra lift required,
However, drag will also increase by the same proportion so lift/drag ratio will stay the same.
Likewise, if you are light, you will need less speed to keep the same lift/drag ratio.
So, for any given weight, there is only one speed that will produce the best glide performance. Faster or slower than that will reduce the glide performance,