Technical Flashcards
(31 cards)
What is critical mach? What happens to the center of pressure/lift as we enter mach tuck?
Mach tuck is an aerodynamic effect, whereby the nose of an aircraft tends to pitch downwards as the airflow around the wing reaches supersonic speeds. The aircraft will be subsonic, and traveling significantly below Mach 1.0, when it first experiences this effect. As the wing becomes more affected by the shock wave the center of pressure will continue to travel aft, thereby causing a significantly higher nose-down force and requiring a nose-up input or trim to maintain level flight. Although Mach tuck develops gradually, if it is allowed to progress significantly, the center of pressure can move so far rearward that there is no longer enough elevator authority available to counteract it, and the airplane enters a steep, sometimes unrecoverable dive
What are holding speed restrictions?
0-6000: 200kts 6001-14000: 230kts 14,001 and above 265kts
Why do airliners all have swept wings?
Swept wings reduce airflow acceleration over the wings and delay crit mac. The airflow is divided into span-wise flow and chord-wise flow. As airflow acceleration is now reduced over the wing, the airplane can now go faster before you experience shockwave and the resultant drag.
Swept wings delay airflow separation due to the shockwave from approaching the speed of sound thus increasing the aircrafts critical mach number ( you can fly faster)
Decode a METAR and TAF
Know the “began” “end” times for rain/snow.
Know the abreviations for: TCU, DSNT SW… Towering Cumulus distant southwest.
What is Mach Buffet?
This is a flow separation of airflow over the wing. This can be from to high of an airspeed (flow desperation at crit. mach), or can be from to high of an AOA.
What is bypass air and what is the benefit?
Typically bypass air makes up 80% of the air that is sucked into the engine (turbofan). Bypass air flows between the core of the engine and the outside casing. The benefit of using so much bypass air is both fuel efficiency and it’s quieter than a full-on jet engine.
What is a Yaw Dampener?
A gyro operated stability augmentation auto control system installed to automatically provide immediate rudder input when necessary to aid in canceling out yaw tendencies such as those of Dutch roll. Basically an autopilot for the rudder.
What is Dutch Roll?
A Dutch Roll is a combination of rolling and yawing (coupled lateral/directional) oscillations that normally occurs when the dihedral effects of an aircraft are more powerful than the directional stability
Where does the stall occur first on a swept wing aircraft?
At the wingtips
What are some things inside a turbine engine to provide positive air flow?
A variable geometry(VG)system regulates airflow through the compressor by changing the position of the compressor inlet guide vane and the variable geometry stator vanes on the first five stages of the compressor. This is done to prevent compressor stall and surge by optimizing the angle of attack of the vanes. TheVG system is controlled by the fuel control unit (FCU) which uses high-pressure fuel to hydraulically move two actuators which are mechanically linked to the VG system. CRJ-200
When you can proceed down past the DA(H)
91.175
What is the maximum airspeed permitted in a hold between 0-6,000ft , 6,001ft-14,000ft, and 14001ft and above?
Holding Speeds 0-6000’ = 200 knots 6,001’ - 14,000’ = 230 knots 14,001 and above= 265 knots
If you’re flying at exactly 10,000ft what is your speed restriction?
Mach 1
91.117 states BELOW 10,000’ no greater than 250 knots. Not AT.
How long is a TAF valid for?
24 or 30 hours.
What is an ILS hold short line? What’s it protecting? Glide slope or localizer? (Ladder symbol)
Critical area when conditions are below 800/2 where you may be asked to hold short. It protects either the LOC signal, GS signal, or both, depending on the airfield and location of taxiway
Speeds in and around class B, C, and D.
Beneath Class B or in VFR corridor through Class B — 200 kias. Class C or D airspace (at or below 2,500 feet agl within 4 nm of the primary airport) — 200 kias (unless a higher speed is specifically approved by ATC) Class E or G airport traffic pattern — 200 kias (recommended)
What to do if you find yourself getting closer to coffin corner?
Request lower altitude.
What if you were coming in on an approach , past the FAF, you have the runway in sight and the tower tells you visibility is below the required minimums, can you continue?
Yes. Prior the FAF, you can’t continue the approach. Past the FAF, you may descend until DA/MDA
What is used from the engine’s bleed air?
Engine and wing thermal anti-ice, also used for pressurization, environmental heating and cooling.
What is the difference between A/C and D/C electricity and which is better ?
Alternating current vs. direct current. A/C is lighter weight and more stable.
What is the FAF for the ILS?
GS intercept
What is the purpose of the turbine? (not a turbine engine)
High Pressure Turbine has one purpose. To turn the High Pressure Compressor Low Pressure Turbine has two purposes. Turn the Low Pressure Compressor and turn the Fan at the front of the engine.
You’re in the lateral boundaries of LAX Class B airspace, but under the actual airspace. What is the max airspeed you can fly?
200 knots
What happens to speed of sound with decrease in temp or pressure?
Book “Illustrated Guide to Aerodynamics” page 190 states “Because molecules move about faster at a higher rate of speed in warmer air they…transmit sound faster.” As pressure and temperature decreases, the speed of sound also decreases.
