Category: Aviation Knowledge

Camshaft, Crankshaft, rpm?

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What’s glide ratio?

Ref FTA material, Skybrary https://skybrary.aero/articles/glide-performance#:~:text=Description,altitude%20lost%20in%20that%20distance.     The glide ratio for the DA40 is approximately 10:1 What’s glide ratio? The Glide ratio of an aircraft is the distance of forward travel divided by the altitude lost in that distance. (It is talking about same unit~)   Below is another example: For every 1.45 NM (2.68km Read More

bank angle and descent angle 證明本書點解d 角度可調位

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Hot topic : Turbofan Engine

How does a turbofan engine work? https://aeroreport.de/en/video/wie-funktioniert-ein-turbofan-triebwerk Air is ingested, compressed, combusted and then expelled.  The GE90-115B on B777-300ER Gearbox Turbofan Engine ? https://aeroreport.de/en/good-to-know/wie-funktioniert-ein-turbofan-triebwerk-aufbau-eines-triebwerk In conventional engines, the low-pressure turbine and the fan sit on one shaft, but here the gearbox decouples the two components. This lets the components run at their optimum speed: the Read More

The properties of air

Ref Ref FAA-H-8083-25C version 2023 Air is fluid To describe the properties of air, we need to know various key terminology at the beginning Viscosity Friction Pressure Density Temperature   Viscosity “friction” of fluid is used to describe the resistance of flowing high viscosity means “thick” and resist flowing low viscosity means “thin” and flow Read More

Vx, Vy, Vcc

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一次搞清楚Ceiling

Ref FAA-H-8083-25C version 2023 5-24, 7-12, 11-8,12-17 Ceiling related to metrology? Ceiling is the lowest layer of clouds reported as being broken (5/8) or overcast (8/8) OR the vertical visibility into an obscuration like fog or haze     Ceiling related aircraft performance? absolute ceiling : the altitude at which the aircraft has no excess Read More

When the air is stable?

Ref: https://skybrary.aero/articles/lapse-rate 到底咩情況下parcel of air 叫stable? To answer this question, we need understand few concept: 咩係Lapse rate 咩係環境上面既Lapse rate 咩係pacel of air 既Lapse rate   Lapse Rate is the rate at which temperature changes with height in the Atmosphere. In my language, how many degree Celsius drop when vertical distance increase for a fixed number.   Read More

Monsoon in Arizona

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What’s Monsoon Wind ; Why Monsoon blow from north east in winter and southwest in summer?

Ref: https://www.hko.gov.hk/en/publica/gen_pub/files/sms_Urdu.pdf https://www.hko.gov.hk/en/education/weather/meteorology-basics/00010-geostrophic-wind.html https://www.hko.gov.hk/en/education/weather/monsoons/00068-why-the-winter-monsoon-in-hong-kong-is-generally-called-the-northeast-monsoon.html   所謂季候風就係會隨著季節改變既風, 但光是研究呢個季候風既風向都搞左我粒幾鐘, 因為背後講緊既CONCEPT 有好幾個: 咩叫High pressure system, 咩叫Low pressure system 咩係風 咩叫Coriolis effect (科里奧利力/科科氏力) 咩叫Geostrophic Wind (地轉風)   想簡單D咁理解就要背少少野 (明白少少基本CONCEPT) High, Low pressure system 是相對 (relative) : compare one air mass with another one 仲要記得通常凍就係有高壓區, 熱就係有低壓區~ 風就是due to two air mass has pressure difference and so the pressure gradient as Read More

ETOPS ? EDTO?

https://www.flightglobal.com/cathay-etops-okay/10579.article The timestamp of this article disclosed that CX A330 has already obtained ETOPS 120 in 1996. https://simpleflying.com/etops-banned-areas/ This article gave us some background information about ETOPS, and told us one of the reasons why B747 was popular in 1980s: Before 1985, all twin aircraft had to remain within 60 minutes of a suitable diversion airport. This Read More

口訣勿背錯: True Direction – Magnetic Direction – Compress Direction

Magnetic Direction 東減西加 轉 Compress Magnetic Direction 東加西減 轉 True   Tommy = M+E C = M-E (我無左E就係死屍)   Read More

What’s coffin corner?

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 Read More

What’s Triangle of veolocities?

Reference : HKU Space materials Ans: it is using a vector concept to explain the relationship between HDG/TAS, TMG/GS and WV   Since the wind ‘blows’ the aircraft from its air position (expected final position) to its ground position (actual final position), it is acceptable to assume that if the air position and the ground Read More

What’s fix ? Pinpoint ?

Refer HKU SPACE materials Ans: Fix – the geographical position of an aircraft at a specific time determined by either visual reference to the ground or by navigation aids Pinpoint – fix determined by direct observation of the ground. Read More

Air Navigation

What is the 5 basic elements in air navigation? Ans:  Direction Distance Speed Wind Time   Air navigation can be basically divided into 2 part: Flight Planning and Flight Monitoring. It is talking about foresee and actual! Flight planning First of all, we need to set a route (where are we going to fly to) Read More

How can we know the variation? 

Reference: HKU Space material Ans: get the variation from chart   Isogonal(s) are the lines on map showing equal magnetic variation. Both FAA and Airservices Australia have issued “aeronautical chart user guide”. Read More

What’s Variation, Deviation?

Reference : HKU Space Material True poles are the location of the geographic poles. Rightly, the true north pole is not at same location of magnetic north pole. Variation : angular difference between true direction and magnetic direction Deviation : angular difference different between magnetic direction and compass direction Read More

Quick fact: Date, Time, Direction in aviation industry

Reference : HKU Space Material Date, Time are taking reference from coordinated universal time (UTC), also known as “Zulu” Time Date: three pair of digit – year-month-day (e.g 010131 -> 2001 Jan 31) TIme: four-figure group – HH:MM (e.g 2300Z, 2359Z, 0000Z) Direction: three way to describe direction – True direction, Magnetic direction, Compass direction; Read More

What’s Heading? What’s Track?

Reference: HKUSPACE Course Heading? Ans: Heading (HDG) refers to the direction in which the aircraft is pointing.   Track? (= Track Required, TR) Ans: Direction over the ground in which the aircraft is required to travel   Read More :- 10 *** Important: Drift is NOT the Track Error. Drift is the difference between heading Read More

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