Cruise Performance Flashcards
Back of the drag curve
MORE or LESS power is required to overcome ____ drag at HIGH or LOW AoA
- MORE
- INDUCED
- HIGH
Flying slower, need to create more lift.
More lift comes from increased AoA
Typically flying with flaps down. More flap produces more induced drag
What is meant by
Maximum Level Flight Speed
in context of power
Where max power available meets max power required
No more power can be produced and to maintain the given speed, the max power setting is required
What does the Maximum Level Flight Speed graph look like
What is on the X axis
What is on the Y axis
- Upwards Tick line for speed. Power line intercepts at a high speed point
- Speed - Knots
- Power Req - HP
What is meant by
Best Endurance Speed
Maximum amount of time aircraft can be airborne
Minimum power required to maintain given altitude
What does the Best Endurance Speed graph look like
What is on the X axis
What is on the Y axis
- Horse shoe power required line, shallow sloped max power line. Best endurace vertical line at point of lowest power required
- Airspeed
- Power Setting
What is meant by
Best Range Speed
Range is a function of SPEED and POWER
Must account for wind i.e. headwind or tailwind
Headwind Best Range Speed
A headwind will result in a HIGHER or LOWER airspeed
HIGHER
50kt headwind with 50kts IAS means aircraft has zero range. More speed is required to overcome headwind.
Tailwind Best Range Speed
A tailwind will result in HIGHER or LOWER airspeed
LOWER
Wind from behind giving aircraft momentum. Means less airspeed required to produce the same airflow over the aerofoil, so less power required. Less power means less airspeed
CoG is designed to be FORWARD or AFT of the CoL (Center of Lift)
FORWARD
With a forward CoG, the nose will tend to pitch UP or DOWN
DOWN
With a FORWARD CoG, performance is INCREASED or DECREASED
DECREASED
Forward CoG requires more down force from tail plane
Down force adds weight, which requires more lift
More lift requires more AoA which creates more drag
More drag requires more airspeed to overcome
With an AFT CoG, performance is INCREASED or DECREASED
INCREASED
Aft CoG requires less down force from tail plane
Less down force means less weight, which requires less lift
Less lift means a reduced AOA required, which reduces drag
Less drag means less airspeed required
Redcued air densitiy will result in MORE or LESS engine power available
LESS
Less air to mix with fuel
Reduced air density will result in MORE or LESS efficient aerodynamics
LESS
Thinner air creating less lift
Pitot Head
What is meant by position error
Less accurate indiciation as a result of high AoA producing less airflow into pitot
What is the definition of CAS
IAS corrected for instrument and position errors
For an aircraft to read the same ASI at higher altitudes, what must the aircraft do
PHYSICALLY TRAVEL FASTER
Less air molecules at altitude. ASI calibrated to measure the number entering the pitot tube.
Since molecules are “more spaced out” , aircraft must travel faster to register same reading.
Airspeed
What is meant by Density Error
ASI Calibrated for ISA
Deviation from ISA will result in an error
If its colder or warmer at a given altitude than ISA, this will result in error readings since ASI is calibrated for ISA
Airspeed values and corrections
What are the definitions of;
1. IAS
2. CAS
3. EAS
4. TAS
Correction calibrations
REMEMBER: I Can Eat Tikka Masala
- Corrected for position and instrument error
- Corrected for compressibility
- Corrected for Density altitude
- Physical speed of aircraft
At altitude, the wind BACKS or VEERS in the NH
VEERS
Below 2000 ft or at ground level, the wind BACKS or VEERS in comparision to that at altitude in the NH
BACKS
How many feet in 1nm
6080 ft
Calculate the glinding range (nm) in still air for an aircraft at 6500ft altitude with a glide ratio of 1:4
4.28 nm
For every foot lost in altitude, we will flight 4 feet.
6500 x 4 = 26000 ft that we will glide in total
Need to convert to nautical miles.
6080 ft in 1 nm
26000 / 6080 = 4.28 nm
A heavier aircraft will need MORE or LESS speed to maintain best glide range
MORE
Heavier aircraft needs more lift
More speed will maintain glide range whilst maintaining required lift produced through going faster.
Glide distance changes for a given aircraft with more weight
TRUE or FALSE
FALSE
Distance remains unchanged irrespective of weight. Glide speed will change as more speed required to maintain lift.
Headwinds and Tailwinds have an effect on Rate of Descent (ROD) for an aircraft in a glide
TRUE or FALSE
FALSE
Headwinds and tailwinds have an effect on the effective glide angle of an aircraft in a glide
TRUE or FALSE
TRUE
A headwind will make an aircrafts effective glide angle STEEPER or SHALLOWER
STEEPER
LESS ground distance covered
A tailwind will make an aircrafts effective glide angle STEEPER or SHALLOWER
SHALLOWER
MORE ground distance covered
During an engine failure, a windmilling propeller will add more what that effects performance
MORE DRAG
How can a pilot stop the wind milling effect
REDUCE AIRSPEED
Almost to stall point
If airspeed is reduced to stop wind milling effect, how much extra glide performance can be achieved
20%
What are 3 additional factors that can effect cruise performance
(not tail or head winds)
- RAIN
- ICE
- FLAPS
What 4 effects does rain have that impact on cruise performance
- Lift reduced
- Drag increased
- Airframe weight increased
- Airflow/laminar flow interference
Ice on aerofoils will affect ____ and will result in what 2 issues
- Aerodynamics
- Lift reduced
- Drag increased
How can a pilot reduce speed whilst maintaining the cruise
Why would they do this
- Flaps
- Deteriorating weather/Visibility
