Aero Test Flashcards
Lift vs drag impact on airfoils
Lift is the force component perpendicular to oncoming flow. Contrasts with drag force, which is the component of surface force parallel to oncoming flow.
What causes airfoil to stall?
Stall occurs when AoA is increased beyond critical AoA and lift begins to decrease.
Relationship between flaps and angle of attack
For the same AoA, CL will increase with flaps extended
What will raising flaps do (if extended) during stall recovery?
- change effective AoA
- increase stall speed due to lower CL
- reduce lift
- increase sink rate
Definition of refusal speed
The maximum speed an aircraft can accelerate on all 4 engines and stop in the remaining runway available with following limits:
- 1 engine windmilling (legacy)/ feathered (J)
- one engine in ground idle
- 2 symmetrical engines in reverse
- max anti skid braking
Definition of Vmca1
Min speed at which you can loose and engine and still maintain directional control, based on this configuration:
- # 1 windmilling on NTS (legacy)/ feathered (J)
- max power on remaining engines (legacy)/ T/O power commanded and ATCS operating
- bleeds off (legacy)
- max rudder deflection 180lbs (legacy)/ 150lbs (J)
- flaps 50%, gear down
- (J) zero rudder trim, min flying weight
What does definition of Vmca1 guarantee?
ONLY guarantees you can overcome yawning and rolling tendencies with max rudder and aileron (as a function of temp/PA). NOT maintain level flight. Level flight is function of power available vs GW and that you can maintain an AoA for that weight.
Define critical Field Length (CFL)
Legacy - the greater of the total rwy distances, balanced or unbalanced, required to accelerate on all engines, experience and engine failure, then either continue the T/O or stop
J model- the total rwy distance required to accelerate on all engines to Critical engine failure speed, experience and engine failure, then continue the T/O or stop within the same distance
What is cruise ceiling
The altitude at which the max rate of climb capability at max continuous power, and best climb speed is 300 ft/min
What is service ceiling
The altitude at which the max rate of climb capability at max continuous power, and best climb speed is 100 ft/min
What is drift down (100 fpm)
The forced descent due to loss of engine
- maintain drift down speed until descent drops to 100 fpm
- maintain 100 fpm down to appropriate 2/3 engine service ceiling
Most descents are flown as __________
En route descents
List types of descents
- Maximum range: flight idle, clean config - L/D Max
- Penetration: Max range to 20K ft - 250 knots to level
- Rapid Configured: flight idle, gear down, 100% flaps - 145 it to level
- Rapid Dive Speed: flight idle, clean - dive speed to level
Which descent profile take the least distance, what are the controlling factors, and what happens to drag at higher density altitudes?
- Rapid descent at dive speed
- Drag and GW
- drag has less effect at high density
Impacts and disparities between power-on and power-off stalls
- Blown lift
- 46% wing area immersed in prop slipstream (blown wing effect)
- high velocity air flow, especially at high power settings
- separation of boundary layer delayed on control surfaces
Doghouses
reference one note pictures
Understand wingtip clearances and wing drop
- wing tip is not level with belly of acft until 10.3 AOB
- ROT: wing drops 10 ft for every 10 deg AOB
Describe basic forces on aircraft
- To counter moment caused by net lift acting aft of the CG (center of lift aft of the CG is required for stability), the horizontal stabilizer produces balancing tail load.
- Fwd CG = more “down” lift required by tail
- more lift = more Di (induced drag)
- more Di = more total drag
- fuel burn moves CG fwd
Define/describe structural stresses (bending, shear, etc)
- Torsion: twisting of a body by the exertion of forces tending to turn one end about a longitudinal axis, while the other is held fast or turned in opposite direction
- Bending: the moment created by a transverse deflection of a body through and perpendicular to its longitudinal axis
- Shearing: a force tending to cause deformation of a material by slippage along a plane or planes parallel to the imposed stressed
Understand load limits
- LL assume no corrosion, fatigue or other damage
- If LL factors are exceeded, acft will suffer permanent
objectionable deformation - Exceeding LLF doesn’t always result in permanent failure of
Primary structure
- If LL factors are exceeded, acft will suffer permanent
- Exceeding Ultimate Limit (UL) may cause catastrophic failure
- UL factors by definition are 1.5 times the LLF
- Overtime, structural damage may lead to structural failure
How are asymmetric forces distributed
Max loads for unsymmetrical maneuvers are less than for symmetrical maneuvers. Check rolls/reversals greatly increase wing up bending for the down aileron wing.
Ops limits for load limits (bank/flaps)
Do not exceed…
- 60 deg AOB with flaps retracted
- 45 dog with flaps extended
- max 2.0g symmetrical/ 1.5g asymmetrical
What is indicated by the g-meter and where is it measuring
Pilots g-meter reads the load factor accurately only at its location. The g-load at at the CG may be be quite different.
Fin stall recovery
- Reduce rudder force and/or use opposite rudder to bring acft back to coordinated flight
- DO NOT apply full opposite rudder, structural damage and/or departure from controlled flight could occur
- Smoothly recenter ball
Why is fuel management important
Different combos of fuel load and distribution in the tanks impact the acft load limits.
- Most of fuel is stored in wing tanks
- Weight distribution can increase/decrease wing bending
- Fuel in outboards decreases wing bending
- Fuel in all other tanks increases wing bending
- combo of up-bending/ torsion moments may limit airspeed
- For any GW, the least wing bending in flight is with #1 & 4 tanks full
Difference between symmetrical and asymmetrical maneuvers
Symmetrical- maneuvers performed with ailerons neutral
- limited to 3.0g in area A
Asymmetrical- maneuvers performed with ailerons deflected
- limited to 2.5g in area A
T-storms penetration and turbulence speed
Power off stall +65 kts, 180 max (181-J)
Compromise for stall margin and prevention of structural damage
Stall Characteristics of Stall Warning
- Progresses from light to moderate to heavy buffet
- Buffet intensity increases with increased GW
- 0% flap light buffet precedes stall by 5-9kt, increasing to moderate buffet
- Higher intensity buffet and more abrupt with flaps extended
- Greatest stall warning margin with 50% flaps, less at 0 and 100
Stall Recovery (exceeded AoA causes stall)
- MAX, RELAX, ROLL
- Altitude/energy permitting reduce AoA (back pressure)
- Throttles flight idle if power is asymmetrical
- Control roll with ailerons as these are last to stall
- Rolling out reduces AoA, potentially breaking accelerated stall
- Add power if available
Why you stall as a function of AoA
The point where an increase in AoA no longer produces an increase in CL…or where critical AoA is exceeded
Critical engine failure speed (CEFS)
Max speed the acft can accelerate on 4 engines, lose an engine, and either continue takeoff or stop within charted critical field length
Rotation speed (Vrot)
(U/W) normal rotation speed is Vto -5 kts; not less than Vmca
Min control speed ground
Minimum speed during ground run at which you can lose an engine and still maintain directional control
MFLMETO
Length of runway required to accelerate to decision (refusal) speed, experience an engine failure and stop, or continue acceleration to 1.2 pwr on stall speed (U/H)….1.05 Vmu4 (J) in remaining runway
