C12 - Total and Polar Drag Flashcards
What is Total Drag (2)?
- Induced Drag.
- Parasite Drag.
When flying faster what happens to Parasite Drag?
Increases.
When Straight and Level, Induced Drag ‘____’ with Speed?
Decreases.
What does Vmd stand for?
Minimum Drag Speed.
When does Minimum Drag Speed occur?
When Total Drag decreases to a minimum at some value of forward speed.
At Vmd, Induced Drag is ‘____’ to Parasite Drag?
Equal.
True of False. An Aircraft is said to be Speed Stable if it shows a natural tendency to return to its original speed following a brief disturbance?
True.
When does Speed Stability occur?
When flying at speeds greater than Minimum Drag Speed.
True of False. An Aircraft is said to be Speed Unstable if it shows a natural tendency to diverge from its original speed following a brief disturbance?
True.
An Aircraft flying in a Speed Unstable regime requires ‘____’ inputs from the Pilot to maintain a stable speed?
Constant.
At what stage of flight can Speed Unstable occur?
Approach to Landing.
What happens to the Drag Curve when plotted against IAS with regards to Altitude?
The IAS does not change with Altitude.
What does Vimd stand for?
Indicated Airspeed for Minimum Drag.
Why does the Drag Curve move to the right when plotted against TAS?
Because of the reduction in Air Density.
Flaps, Slats and Landing Gear all increase what type of Drag?
Parasite.
Flaps, Slats and Landing Gear can also slower what?
All Speeds including Indicated Airspeed for Minimum Drag.
What is the Total Drag equation?
Total Drag ∝ IAS² S Cl.
What is the Coefficient of Drag equation?
Cdp + Cdi.
True or False. Parasite Drag varies with Angle of Attack?
False.
What is the Cdi equation?
Cl² ÷ Aspect Ratio.
What must occur when Cl/Cd max?
Minimum Drag Speed.
What is the most efficient Angle of Attack with regards to Lift/Drag Ratio?
4°.
At what angle does the Lift/Drag Ratio fall rapidly?
16° (Stalling Angle).
What three elements occur at the 4°?
- L/D max.
- Cl/Cd max.
- Vmd.
