UAV arenduse eesmärk on stabiilne ja kergesti juhitav õhusõiduk maksimaalse aerodünaamilise efektiivsusega. Aerodünaamiline efektiivsus on määratud tõmbe– ja takistusjõu suhtega.
Streamlining has a strong influence on the lift-to-drag ratio (L/D, or C L/C D) of a body. Lift-to-drag ratio is a measure of aerodynamic efficiency. For example, the Boeing 747 jumbo-jet has a lift-to-drag ratio of about 20. This means it can lift 20 lb at the cost of only 1 pound of drag—quite a leverage. In airplane design, an increase in L/D is usually achieved by a decrease in D rather than an increase in L.
