Category: Aviation

What’s boundary layer?

Ref Chapter 5 Ans: the layer of air between the wing and free-stream velocity level   The area between the wing and the free-stream velocity level is about as wide as a playing card and is called the boundary layer. Read More

Free-stream velocity?

Ref Chapter 5 Ans: the speed at which molecules are moving at the velocity that same as the air moving around the aircraft.   Each layer of molecules above the surface moves slightly faster until the molecules are moving at the velocity of the air moving around the aircraft. This speed is called the free-stream Read More

Skin friction Drag?

Ref Chapter 5 成因: contact of moving air with the surface of an aircraft 解決/緩解方法: flush mount rivets remove any irregularities that may protrude above the wing surface smooth and glossy finish remove dust and dirt   no matter how apparently smooth, has a rough, ragged surface when viewed under a microscope Read More

Interference Drag?

Ref Chapter 5   成因: intersection of airstreams (that creates eddy currents, turbulence, or restricts smooth airflow) 解決/緩解方法: Fairings    most interference drag is observed when two surfaces meet at perpendicular angles (e.g wing and wing root)       Read More

Form Drag?

Ref Chapter 5 成因:   shape and airflow around the airfoil (aircraft) 解決/緩解方法: streamline                                   (as many of the parts as possible)   When the air has to separate to move around a moving aircraft and its components, it eventually rejoins Read More

Parasite Drag?

Ref Chapter 5 Three sub-type of parasite drag Form Drag Interference Drag Skin Friction Drag not associated with the production of lift Types of Drag? Read More

Types of Drag?

Ref Chapter 5 Ans: Parasite Drag, Induced Drag Read More

Air Density , 3H?

Ref Chapter 5   Ans: Air Density drop (air becomes less dense) when  High altitude  (高度)  High temperature   (溫度)  High humidity  (濕度) Read More

What’s stalling AoA? What’s CL-max Critical AoA?

Ref Chapter 5   Ans: the AoA at which after that the acft will stall! Remember: aircraft (airfoil) always stalls at the same AOA! When the aircraft reaches the maximum AOA, lift begins to diminish rapidly. This is the stalling AOA, known as CL‑MAX critical AOA.   Notes: generally, 20° AOA is the critical angle Read More

Relationship between Speed and AoA?

Ref Chapter 5 Ans: Speed decrease, AoA need to be increased (and vice versa)   Reason is simply, refer to the lift formula, to generate same amount of lift, one factor drop, then another factor must be increased.   Lift formula Read More

Lift formula

Ref Chapter 5   Ans: Lift = 1/2 * CL * p * V2 * S   where CL : coefficient of lift –> related to AoA p : Air Density V: Airspeed S : Wing Surface   What’s 4 forces?       Read More

What’s AoA – Angle of Attack?

Ref Chapter 5 Ans: angle between chord line and the direction of the relative wind Read More

4 forces in steady flight?

Ref Chapter 5 Ans: sum of 4 forces is always zero, provided that it is a steady flight!   Steady flight? -i.e unaccelerated status! Based on Newton’s 3rd law (every action or force there is an equal, but opposite, reactionor force.) However, amount (magnitude) of 4 forces not exactly same! Weight cancel out by Lift Read More

What’s 4 forces?

Ref Chapter 5 Ans: Lift, Drag, Thrust, Weight   Thrust— forward force produced by the powerplant/propeller or rotor opposes force of drag. act parallel to longitudinal axis (in general but not must)   Drag— rearward, retarding force caused by disruption of airflow by the wing, rotor, fuselage, and other protruding objects drag opposes thrust (in Read More

The road to become a professional bus driver before being an airline pilot

2020 Apr 17, around 3 months past since the outbreak of COVID-19 , I wake up at 0500LT. This first thing I am going to do is to type a simply “diary” to record my recent status. I like writing blog since I can review what I did in the past and I can check Read More

Life as a Flight Operations Officer

In 2019, before I am going to work for other company in another sector of aviation, I would like using little spare time to review my past position as a Flight Operation Officer. From about video clip, you may see the lady wears a yellow high-vis vest with “RC” imprint on it. RC- could refer to Read More

One Life Experience

2017-01-03 Dear my friends, There is no better way for greeting, isn’t it. Tonight, it is great that I can go back to campus again after I have started to work as a member in Flight Ops since July. Time is passing, always! Everything is happening liken to blinking my eyes. Originally, I tried to Read More

One Life Experience

Dear my friends, 2016-03-20 The performance may be reduced due to the high relative humidity in the damp night. However, I feel that it’s not a big deal since I have learnt how to make a wisdom decision as a pilot point of view – of coz,  I start from “ab initio” – there are much Read More

Life-long Learning: 人生是不斷修正的過程~

2015.09.01 I have come back Hong Kong almost a month. Rightly, as a fresh graduate, without any working experience as well as not the “first-hon” graduate, it is very difficult to seek for even an interview here. Fortunately, my boss choose to believe in me and offer an excellent position to me so that I Read More

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