Lift and Drag Flashcards
Lift equation
L=1/2 ρv^2SC
Drag Equation
D=1/2 ρv^2SC
2 main types of drag
Induced drag and profile drag
3 types of drag that make up profile drag
Interference, skin friction and pressure drag
What is pressure drag? How do we reduce it?
Related to the shape of the object. Change frontal area, streamline, boundary layer control
What is skin friction and how do we reduce it?
Viscous dragging effect of the boundary layer on the skin of the aircraft. We reduce the surface area, reduce length of fuselage, smoother surface, keep BL laminar
What is interference drag and how do we reduce it?
Caused by 2 airflows mixing after moving around different components. We reduce the number of components, use contoured panels or reposition the component.
What is induce drag and how do we reduce it?
High pressure under the wing spills over the tip and mixes with the low pressure on top of the wing and causes tip vortices. We use winglets, high aspect ratio wings, tapered wing plans or washout.
What is washout?
Reduction in the angle of incidence towards the wind tip
What is aspect ratio? What are the two formulas?
Ratio between spam and chord.
AR=span/chord
AR= (span)^2/wing area
What is the taper ratio? And what is the formula?
How quickly a wing tapers
TR= tip chord/root chord
Rectangular wing characteristics
Even spanwise pressure distribution👎
High induced downwash at the tip👎
Stalls at the root first 👍
Moderate tapered wing characteristics
Neat ideal spanwise pressure distribution
Low induced downwash
Sudden stall with little warning, whole wing stalls at the same time
Swept wing characteristics
Bad at low speed
Tip stalls first, nose up 👎
Good at high speed
Good lateral stability
Delta wing characteristics
Bad at low speed
Tip stalls first, nose up 👎
Good at high speed
Good lateral stability
(Same as swept)
