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## Cl, Cd, Cl/Cd graphs

• Posts: 3

### Travis Rozario created the topic: Cl, Cd, Cl/Cd graphs

Hello all,

I would just like some clarification with regards to the following MOS extract. I am currently studying to sit the exam and have just completed the Bob Tait text book (fantastic). However I can't seem to remember doing much work on the following.

2.1.2 With reference to CL, CD, CL/CD graphs identify angles of attack associated with the following:
(a) minimum drag – maximum level flight speed;
(b) maximum lift – stalling angle;
(c) best CL/CD – best glide range and still air range.

I am aware that Cl and Cd re not the same as the Lift and Drag curves which I am very familiar with. I just need assistance with the above and understanding those points.

Any and all help is greatly appreciated.

-Trav

• Posts: 168

### Carello replied the topic: Cl, Cd, Cl/Cd graphs

This chart might help.
Note: For this wing, the stall occurs at an AoA of 19.8 degrees and the L/D max occurs at an AoA of 5.5 degrees.

(a) minimum drag – maximum level flight speed;
Occurs at the AoA for L/DMAX - ie 5.5 degrees for this wing

(b) maximum lift – stalling angle;
Occurs at the AoA for max CL - ie at 19.8 degrees for this wing.
Note: An AoA of 19.8 will produce the max lift for a given IAS

(c) best CL/CD – best glide range and still air range.
The AoA for L/D MAX is 5.5 degrees for this wing. The best glide and best still air range will occur at an AoA of 5.5 degrees for this wing.

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The following user(s) said Thank You: Travis Rozario