Explain the four forces of flight and how each affects an aircraft in straight-and-level flight.

Explanation should include 

• lift—provides elevation 
• thrust—provides forward motion 
• drag—impedes/slows forward motion 
• weight—pulls aircraft toward Earth. 

Process/Skill Questions: 

• How does weight affect aircraft performance? 
• What are causes of drag? What effect does drag have on an aircraft?