chris
Well-Known Member
Hey guys,
In regards to the effects of a windmilling prop....
Theoretically, you should be using the same AOA (and hence, IAS) to achieve a minimum sink glide, as compared to flying for max endurance. In both cases, you are looking for the AOA where the lowest power is required.
The same thing applies to a best distance glide and flying for max range- in this case, you fly at the AOA where the lift/drag ratio is maximized (also considering prop efficiency and BSFC).
Now, the IAS to use is lower in the case of the glides because these are power-off scenarios and your prop will be windmilling, producing a lot of drag.
If the drag is higher with your prop windmilling, and the goal is to maintain the correct AOA, why do we use a lower IAS and not a higher one?
For example, in the best distance glide, we fly at the best L/D AOA. If our prop is windmilling, there is more drag. To keep the ratio the same, more lift needs to be produced. The only way to achieve this is by increasing IAS.
What am I misunderstanding? I just don't understand why we use a lower IAS in the power off situations, where drag is very high.
Thanks for any responses.
In regards to the effects of a windmilling prop....
Theoretically, you should be using the same AOA (and hence, IAS) to achieve a minimum sink glide, as compared to flying for max endurance. In both cases, you are looking for the AOA where the lowest power is required.
The same thing applies to a best distance glide and flying for max range- in this case, you fly at the AOA where the lift/drag ratio is maximized (also considering prop efficiency and BSFC).
Now, the IAS to use is lower in the case of the glides because these are power-off scenarios and your prop will be windmilling, producing a lot of drag.
If the drag is higher with your prop windmilling, and the goal is to maintain the correct AOA, why do we use a lower IAS and not a higher one?
For example, in the best distance glide, we fly at the best L/D AOA. If our prop is windmilling, there is more drag. To keep the ratio the same, more lift needs to be produced. The only way to achieve this is by increasing IAS.
What am I misunderstanding? I just don't understand why we use a lower IAS in the power off situations, where drag is very high.
Thanks for any responses.