Performance and Limitations Flashcards
What is relative wind?
The direction of wind relative to an airfoil. It is parallel and opposite the path of the airfoil’s movement.
What is Bernoulli’s principle?
The principle that lift is based on, stating that pressure is inversely proportional to velocity. The low velocity, high pressure on the bottom of the airfoil wants to move towards the high velocity, low pressure on top of the airfoil, thus causing lift.
What is a stall?
a. What factors effect stall speed?
A sudden loss of lift, caused when the flow over an airfoil no longer remains smooth or laminar.
a. Weight and center of gravity
How does an aft CG affect stability, cruise speed, and stall speed?
a. A forward CG?
Aft - Less stabile, higher cruise speed, lower stall speed
Forward - More stabile, lower cruise speed, higher stall speed
What is P-factor?
The affect that causes the aircraft to want to turn/yaw to the left. Due to the downward moving propeller blade (right) taking a bigger bite out of the air and producing more thrust than the upward moving propeller blade (left).
What are the two types of drag and what causes them?
Parasite drag
- Skin - Friction due to the contact of moving air with the aircraft
- Form - produced by the shape of the aircraft and the airflow around it
- Interference - created by the intersection of airstreams of the different areas of the aircraft
Induced drag - by product of lift
What is load factor?
a. How is it normally expressed?
b. What effect does an increase in load factor have on stall speed?
The load the wings are supporting divided by the total weight of the aircraft
a. Normally expressed in G’s.
b. A higher load factor means a higher stall speed, due to a higher AOA to produce the needed lift
How do you calculate maneuvering speed?
Max takeoff weight squared / landing weight squared x max Va
What causes a spin?
a. What is the recovery from a spin?
When the critical AOA is met (stall) and a yawing motion is present.
a. In the Archer - REAP
- Rudder opposite the direction of spin
- Elevator forward
- Ailerons neutral
- Power idle
Define ground effect.
Increased lift generated by the interference of the ground with the air moving around a wingtip. Occurs within a wingspan of the aircraft to the ground.
Define the following weights.
a. Standard empty weight
b. Optional or extra equipment
c. Basic empty weight
d. Useful load (disposable load)
e. Payload
f. Operational empty weight
g. Max gross weight
h. Zero fuel weight
a. Weight of the airframe and engine with all standard equipment installed. Also includes unusable fuel and oil
b. Additional instruments, radios equipment, etc, installed but not considered standard. Also includes fixed ballast, fuel engine coolant, hydraulic and deicing fluid
c. Weight with all optional equipment included. Full oil is usually included.
d. Difference between gross takeoff weight and basic empty weight. AKA all load that is removable. Includes usable fuel, the pilot, crew, passengers, baggage, freight, etc.
e. Load available after the pilot, crew and usable fuel have been deducted
f. Basic empty weight plus the pilot. Excludes payload and usable fuel.
g. Max permissible weight of the airplane
h. Weight of the airplane exclusive of of usable fuel
What are the following types of altitude?
a. Indicated
b. True
c. Absolute
d. Pressure
e. Density
a. Indicated - read directly from the altimeter
b. True - height above sea level
c. Absolute - height above the terrain
d. Pressure - height above the standard datum plane (what altimeter reads if set to 29.92)
e. Density - pressure altitude corrected for nonstandard temperature
How can you calculate density altitude?
(OAT - standard temp) x 120 + pressure altitude
What factors affect density altitude?
Humidity, altitude, temperature
Define the following airspeeds.
a. By what percent does TAS increase per 1000ft relative to CAS?
a. Indicated (IAS) - read directly from ASI
b. Calibrated (CAS) - IAS corrected for installation and instrument error
c. True (TAS) - actual speed through the air
a. Add 2% of CAS per 1000ft to find approximate TAS
