What’s coffin corner?
March 30, 2024
Reference：https://airwaysmag.com/coffin-corner-aviation/ , https://www.boldmethod.com/learn-to-fly/aerodynamics/coffin-corner-where-vne-and-mmo-meet/ Ans: Coffin Corner can be explained by using below illustration. It is talking about when when the aircraft fly to an altitude where the aircraft reduces the speed, it will stall while the aircraft increase its speed, it will over the Mmo. Therefore, the margin for error is low.The coffin corner is
What’s CAVOK , What’s NCD, NSC
March 28, 2024
Reference source: https://skybrary.aero/articles/weather-observations-aerodromes CAVOK The visibility, RVR, weather and cloud groups are replaced by CAVOK (Cloud And Visibility OK) when the following conditions exist simultaneously: If there is no cloud below 5000 ft or below the highest minimum sector altitude (whichever is greater) and there is no towering cumulus or cumulonimbus, ‘NSC’ is reported. Note:
Service ceiling v.s Absolute altitude
March 24, 2024
Service ceiling 指飛機無再多MAP for climb; Critical altitude 指turbocharged engine 發揮最大壓縮空氣能力既高度 As a normally aspirated aircraft climbs, it eventually reaches an altitude where the MAP is insufficient for a normal climb. This altitude limit is known as the aircraft’s service ceiling Critical altitude is the maximum altitude at which a turbocharged engine can produce its rated
Six pack
March 23, 2024
Reference: https://www.airpowerinc.com/six-pack-aircraft-instruments Six pack: is a terms referring the six basic instruments that a pilot must know! From the top, on the most left is the Airspeed indicator (ASI), the Attitude indicator (AI) is in the middle, and the Altimeter (Alt) on the right At the bottom, on the most left is the Turn coordinator
What’s Wing Camber, What’s Chord line?
March 23, 2024
What’s Wing Camber? Ans: curvature of the aerofoil (wing) maximum distance between the mean camber line and the chord line Mean camber line : imaginary line equidistance between the upper and lower surface of the wing, joining from the leading edge to trailing edge. What’s Chord line? Ans: imaginary line joining from the
點樣知機場QNH? 點樣知Local Pressure? How to know the QNH? How to know local pressure?
March 16, 2024
今日上完堂再唸左成個下午先好D 通左D, 所以一定要記底佢…小喇叭, 呢個Concept 好難明! Anyway, mark 低佢先! Reading (in feet) = (Set QNH – Actual pressure level) * 30 For example, if the aerodrome is 30 feet Elevation and 當時QNH是1013, then Reading (in feet) = (Set QNH – Actual pressure level) * 30 30 = ( 1013 – Actual pressure level )＊ 30 30/30
Why “Fly to low, watch below ; High to cold, watch below” ?
March 4, 2024
Ref Ace the technical pilot interview 2/E Ans: Always remember : aneroid barometer is working based on MSL pressure (i.e pressure height) ! 1. FL formula Flight Level (Pressure Height) in feet = Height @ QNH + (1013 – QNH) * 30 Example: Now say 300 feet @ 1025 PH = 300
Maximum Glide Range?
February 29, 2024
Ans : two manoeuvre factors – 1. optimal angle of attack 2. minimum drag speed 當上面兩樣野做到又吾計wind , 理論上隻機就會飛 @ max L/D ratio 記著： 重量同max glide range 無關！ 取決上面說的兩個操作factors – 大機同細機glide range 一樣 ！
Pilot math
February 29, 2024
計數係惡夢 但方法還是有 🤭 Ref skybrary: https://skybrary.aero/articles/rules-thumb 時間 Time 6 mins 0.1 hour 3 mins 0.05 hour 方位 Reciprocal Heading = HDG +200 – 20 or = HDG – 200 + 20 大過200就- 先 ； 細過200就+ 先 e.g 090 : 90 + 200 – 20 = 270 270 : 270 – 200 + 20
Ground effect 對不同flight status 的影響? (就Ground Effect 有咩係機師要知, 有咩要做?)
February 25, 2024
Ref Ch5 Ans: 機師要記著 – T/O phase not attempt to force the acft T/O with not sufficient takeoff speed (due IAS 假象!) never retract the landing gear or flaps prior to establish +ve rate of climb never retract the landing gear or flaps prior reaching MSA (minimum safe altitude) Landing phase reduce power to
Ground effect 有咩影響? Significance of ground effect?
February 25, 2024
Ref Ch5 Ans: Upwash↓ , downwash ↓ –> Wingtip vortices ↓ –> induced drag ↓ –> AOA need to be reduced for same CL Local pressure on static source [position (installation) error] –> airborne IAS reduce 假象 Induced Drag 成因? What’s ground effect?
What’s ground effect?
February 25, 2024
Ref Ch5 Ans: air cushion phenomenon The reason of ground effect is that the air that is trapped between the wing and the landing surface, as if there were an air cushion. When the plane is very close to the surface (say just before touchdown), it would suddenly feel like the plane did not want
Strategy to avoid wake turbulence?
February 25, 2024
Ref Ch5 Ans: 飛緊 : avoid similar flight path with 1000 ft vertical separation T/O : rotate before the point at which preceding acft rotated LAND : approach above preceding acft’s flight path LAND : touch down after the point where other’s wheel contact If doubt, 用 3 mins margin time (rule of thumb) For
When the wingtip vortices are greatest?
February 25, 2024
Ref Ch5 Ans: heavy, clean, slow Vortices 正比 Weight Vortices 反比 Wingspan Vortices 反比 Speed 所以大機, 無落FLAPS, TAKE OFF/APPROACH 果陣最勁~ 因為大機重, 無FLAPS 要產生升力, AOA 自然大, INDUCED DRAG as well as Wingtip vortices 就當然大
點解vortices 係 wingtip ? The formation of wingtip vortices~
February 25, 2024
Ref Ch5 Ans: pressure differential (between upper and lower surfaces of wing) air always moves from high pressure toward low pressure bottom : span-wise movement of air (outward from fuselage to and around tips) upper surface : span-wise movement (flow in toward fuselage and off the trailing edge) fuselage limits the inward flow –
Induced Drag 成因?
February 22, 2024
Ref Chapter 5 Ans: air tends to flow from the high pressure area to low pressure area higher pressure at the bottom of airfoil vortices is created (at wing tip) – wingtip vortices vortices roll off, and create a downwash downwash points the relative wind downward lift is tilted the more the tilted lift, the
