A- explain the construction of the ac induction motor.
B- explain the concept of rotating field and how it is created.
C- explain the working of the rotor
D- calculate the speed of rotating field .
E- calculate slip speed ans speed of the rotor
Many of my students find it difficult to understand the AC induction motors.
It does not matter whether it is 3 phases or 2 phase motor, because the principle is the same.
It needs the understanding of 2 concepts:
- the rotating magnetic field
- the rotor
It is the interaction of the rotating field and the rotor will cause the rotor to rotate.
B. Creation Of Rotating Field
This is better explained by video used by this video
Testing The Armature
There are 2 basic test:
- Using meter
- Using Growler
1. Test Using Gowler
Growler is like the primary winding of a transformer. When the armature is positioned on the growler, the armature is acting like the secondary of the transformer. However, please take note that the secondary winding of the armature is open circuit, so no current flows in the armature windings but there are the induced voltage
of the following phenomena on maintenance practices for electronic system:
HIRF-High Intensity Radiated Field
Slide 2 WHY THE
INCREASED CONCERN IN RECENT YEARS? BECAUSE:
- Greater dependence on electrical and electronic systems for
continued safe flight.
- Reduced electromagnetic shielding due greater use of
- Increased susceptibility of electrical and electronic systems
to HIRF due to increased data bus and processor operating speeds, higher
density integrated circuits and cards, and greater sensitivities of electronic
- Expanded frequency usage, especially above 1 gigahertz (GHz);
Increased severity of the HIRF environment because of an
increase in the number and radiated power of radio frequency (RF) transmitters;
- Adverse effects experienced by some aircraft when exposed to
Slide 3. ADVERSED
The experiences had proven the need consider the threat seriously. Gross
navigation error in a passenger aircraft in USA (from Newark to San Maarten)
caused by a portable tv set used by a
top used by a passenger affected the navigation equipment during aircraft
take-off and landing.
by transmission of electrical energy in space, e.g from radar, radio or TV.
current flowing in a wire, magnetic fields are created.
– Electromagnetic Compatibility
Electromagnetic compatibility, or EMC means that a device is compatible with (i.e.,
no interference is caused by its electromagnetic (EM) environment and it does not
emit levels of EM energy that cause electromagnetic interference (EMI) in other
devices in the vicinity.
electric devices or installations influence each other when interconnected or
close to each other. Eg your TV set, your GSM
handset, your radio and nearby washing machine or electrical power lines.
purpose of electromagnetic compatibility (EMC) is to keep all those side
effects under reasonable control
interference or EMI, also
called radio frequency interference or
RFI. It is the disturbance that affects an electrical circuit due to either
electromagnetic induction or electromagnetic radiation emitted from an
avionics equipments are left unprotected, may cause serious flight safety
OF EXTERNAL INTERFERENCES (note P168)
forms of interference
External Electrical Systems e.g brushes, switches
Engines system – ignition system
Faulty static discharger/wicks
Located aerials – the interference to the comm/nav systems like ADF and VHF
equipment to be grounded and the related wires to be shielded and grounded.
The lighting current flows through the outer
skin and discharge to the extremity.
– all equipments to be bonded together, min R = 0.05 ohms.
Discharger – provide the low resistance path to the admosphere.
Intensity Radiated Fields (electromagnetic
energy) external to the aircraft, of a strength sufficient
to have adverse affect on aircraft
The source of energy is external, exclude onboard system and static sources.
high energy and high voltage can affect the aircraft hardware as well as the
high transient discharge current can damage the skin of the aircraft and the
and current protector at the equipment
ELECTRONIC DEVICES (PED)
Electronic equipments can produce signals that affect electronic equipments.
there was no definitive proof of individual cases. Symptoms and failures went
off when passengers were asked to switch PED.
cautions were founded as some of the sensitive electronic wires run in close
proximity to passengers.
This is rather an old video explaining the function of the gyros in the aircraft instrument. It was produced by US navy and designed for learning.
There were three basic instruments that use the gyros:
- turn and bank indicator
- attitude indicator
- direction compass.
A: Principles of Gyro
a. Construction - A rotating mass mounted on one or two gimbals
b. Properties - There are 2 basic properties used in the application of the gyros.
- precession - it is the way the gyro responds to external force.
- rigidity in space - the rotating mass of the gyro will tend to maintain its axis in space. For the aircraft application, the navigation is in relation to the earth space, as such the axis of the gyro has to be adjusted to be aligned in relation to the earth space.
a. Turn and Bank Indication - It measure the rate of turn of the aircraft. The gyro is mounted on a lateral axis on single gimbal. Watch up for the explanation of precession.
This is an old film, however it is good reference to understand the operation of a mechanical gyro.
Watch The Video..
Learn about the various parts of the Turn and Slip indicator. You must be familiar with, the faces of the indicator and its internal parts.
The face: pointer, turn rate scale, off flag and slip indicator.
The internal parts: The gyro, stator and rotor, the OFF flag arm/linkage and gimbal.
Take note of the axis of the indicator, corresponding to the axis of the aircraft. The gyro is turning on the lateral axis.
- If you roll the aircraft on the longitudinal axis, or pitch the aitcraft, up or down, the effect of the turn indicator.
- If the gyro turn on the vertical axis corresponding to aircraft turning left or right, the indicator will respond giving the rate of turn.
For the purpose of the examination you need to be able to explain the happenings. There are two basic properties that you need to know: Rigidity and Precession.
The property of precession explains why the gyro banks when it moves on its vertical axis. The movement on the vertical axis is transmitted through the axis of the gyro which is equivalent to a force applied at the rim of the rotating gyro mass. The force is shifted by 90 degrees in the direction of rotation.
Airbus is the first to introduce the fly by wire concept in its A320.
The transformation is a planned gradual move from the traditional mechanical cable linkage to control surfaces to present total fly by wire aircraft.
It offers the following main advantages:
1. Performance - as it is an electronic system, the pilots feels and the aircraft responses can be adjusted to a specific performance. Thus aircraft of the same family may be made to feel and behave the same. This eliminate or reduces the hours of crew training.
2. Safety - the active control of the system will ensure that the aircraft operates within a give envelope. For example the bank angle may be limited to specific figure such as 33 degree. So is the pitch angle.
3. Maintenance - It reduces the rigging and adjustment as required by the mechanical cables.
I include the original Airbus pages..
A key element of Airbus’ continued innovation is the application of digital fly-by-wire technology – which brings improved handling, enhanced safety and operational commonality to its product line of modern jetliners.
Introduced into civil aviation with Airbus’ single-aisle A320, fly-by-wire technology has allowed the company to develop a true family of aircraft through the highest degree of operational commonality, featuring nearly identical cockpit designs and handling characteristics.
SAFETY AND PERFORMANCE
Overall safety is increased with the use of fly-by-wire, which provides direct input through electrical signals for more precise commands. In addition, the control system monitors pilot commands to ensure the aircraft is kept within a safety margin called the “flight protection envelope.” As a result, pilots always can get the maximum performance out of Airbus aircraft without running the risk of exceeding these limits.
The use of fly-by-wire technology provides a number of operational advantages for Airbus aircraft, including higher precision during flight and lower maintenance costs.
Operators benefit greatly from this key innovation, which allows for simplified crew training and conversion. In addition, pilots are able to stay current on more than one aircraft type simultaneously without supplementary takeoff/landing requirements, recurrent training and annual checks.
The weight savings from the replacement of heavy mechanical control cables provides a significant reduction in fuel consumption. As electrical controls are less complex and easier to maintain than mechanical ones, the use of fly-by-wire also translates to lower maintenance costs for operators.
Experiences and researches had shown that runway overrun in the major cause of aircraft loss. Through years of continuous research, Airbus had come up with an onboard system to assist in reducing the change of runway overrun. The Airbus-patented ROPS computes minimum realistic in-flight landing and on-ground stopping distances while comparing them to available landing distances in real time. The analyses take into account factors such as runway topography, runway condition, aircraft weight and configuration, wind and temperature. The resulting outcome produces audio callouts and alerts for pilots, making ROPS an awareness tool to assist the crew in the go-around decision making process and also the timely application of retardation/stopping means on touchdown.
Airbus has achieved initial EASA certification of its innovative Runway Overrun Prevention System (ROPS) technology on A320ceo* Family aircraft. This on-board cockpit technology, which Airbus has pioneered over several years and is now in service on the A380, increases pilots’ situational awareness during landing, reduces exposure to runway excursion risk, and if necessary, provides active protection. In March this year American Airlines selected ROPS to equip its A320 Family fleet.
This EASA certification of ROPS on the A320ceo is the next step in making ROPS available for line-fit and retrofit to other Airbus models including very soon the A320ceo with Sharklets, the A330 Family, and also the A320neo**. ROPS was first approved by the European Aviation Safety Agency (EASA) on the A380 in October 2009 and to date is currently in service or ordered on most of the A380 fleet. ROPS is also part of the A350 XWB’s basic configuration.
“Already in service on the A380, ROPS is the result of years of continuing research by Airbus,” said Yannick Malinge, Airbus’ Senior Vice President and Chief Product Safety Officer. He adds: “This initial EASA certification for ROPS on the A320 Family is an important new step to offering the enhanced safety benefits across all our aircraft and for the industry.”
Runway excursion – meaning either an aircraft veering off the side of the runway, or overrunning at the very end – has become the primary cause of civil airliner hull losses in recent years, particularly as other formerly prevalent categories of aircraft accidents have now largely been eliminated. Furthermore, various industry bodies including the EASA, NTSB, Eurocontrol and FAA recognize this and are fully behind the introduction of effective measures by commercial aviation stakeholders to not only mitigate, but eliminate the risk of runway excursions.
In line with this, Airbus is working to make ROPS commercially available for aircraft from other manufacturers. The system will be coupled to the mandatory Terrain Avoidance Warning System already fitted and will utilize an enhanced and specially developed version of its worldwide runway database.
To regularly enhance the A320 Family’s capabilities and performance, Airbus invests approximately 300 million euros annually in keeping the aircraft highly competitive and efficient. More than 9,600 A320 Family aircraft have been ordered and over 5,600 delivered to operators worldwide. With a record backlog of over 4,000 aircraft, the A320 Family reaffirms its position as the world’s best-selling single-aisle aircraft Family.
Airbus is the world’s leading aircraft manufacturer of passenger airliners, ranging in capacity from 100 to more than 500 seats. Airbus has design and manufacturing facilities in France, Germany, the UK, and Spain, and subsidiaries in the US, China, Japan and in the Middle East. In addition, it provides an international network of customer support and training centres.
Those going for B1.1 (Airplane Turbine) License have to take Module 11A.
Module 11A is about the aeroplane aerodynamics, structure and systems. Under the previous BCAR Section L, the licenses were segmented into smaller responsibility area:
- Electrical, plus other licenses.
However under EASA, The Airframe, Engine and Electrical are combined into one single license, B1.1.
However this blog is only focused on the avionics / electrical components. On some system like Electrical Power, there appears to duplication with module 3. I would consider, module 11A is the application of the basic knowledge taught in module 3. In module 3, we learn about the construction and operation of batteries, and in module 11A, we learn about the batteries as fitted to an aircraft.
The syllabus is given below...
11.6 Electrical Power (ATA 24) Level 3 -
Batteries Installation and Operation;
DC power generation;
AC power generation;
Emergency power generation;
Inverters, transformers, rectifiers;
11.8 Fire Protection (ATA 26) Level 3 -
(a) Fire and smoke detection and warning systems;
Fire extinguishing systems;
(b) Portable fire extinguisher Level 1
11.18 On Board Maintenance Systems (ATA 45) Level 2 -
Central maintenance computers;
Data loading system;
Electronic library system;
Structure monitoring (damage tolerance monitoring).
11.19 Integrated Modular Avionics (ATA42) Level 2
Functions that may be typically integrated in the Integrated Modular
Avionic (IMA) modules are, among others:
. Bleed Management, Air Pressure Control, Air Ventilation and Control,
Avionics and Cockpit Ventilation Control, Temperature Control, Air
Traffic Communication, Avionics Communication Router, Electrical Load
Management, Circuit Breaker Monitoring, Electrical System BITE, Fuel
Management, Braking Control, Steering Control, Landing Gear
Extension and Retraction, Tyre Pressure Indication, Oleo Pressure
Indication, Brake Temperature Monitoring, etc
11.20 Cabin System (ATA44) Level 2 -
The units and components which furnish a means of entering the
passengers and providing communication within the aircraft (Cabin
Intercommunication Data System) and between the aircraft cabin and
ground stations (Cabin Network Service). Includes voice, data, music and
The Cabin Intercommunication Data System provides an interface
between cockpit/cabin crew and cabin systems. These systems support
data exchange of the different related LRU’s and they are typically
operated via Flight Attendant Panels
The Cabin Network Service typically consists on a server, typically
interfacing with, among others, the following systems:
- Data/Radio Communication, In-Flight Entertainment Systems
The Cabin Network Service may host functions such as:
- Access to pre-departure/departure report
- E-mail/intranet/internet access,
- Passenger database,
Cabin Core System
In-Flight Entertainment System
External Communication System
Cabin Mass Memory System
Cabin Monitoring System
Miscellaneous Cabin System
With the uses of digital data, the understanding of the basic modulation is required. How does the digital bus carries the data?. Due to this need, I include the learning on the subject from the video produced by the US Department of Defense. The videos produced of the Department are well researched, prepared and intended for training purposes.
AFDX is the acronym for Avionics Full Duplex Switched Ethernet. It is based on the on the shelf commercial ethernet technology with the modification to increase its reliability and deterministic making it relatively on-time.
The picture on the left gives example of the AFDX card supplied by the manufacturer.
The followings are the information supplied by the manufacturer.
1. It is On-board AFDX® protocol stack implementation
2. Airbus and Boeing AFDX® compliant protocol stack
3. Two full duplex AFDX networks that can be operated in either independent or dual-redundant mode
4. Comprehensive error injection/detection, filtering and triggering features
5. Applicable on PCI, cPCI, PXI, PCIe & VME hardware platforms
6. Driver & API support for Windows, Linux or VxWorks
The picture is given to improve the understanding of the networking system used on the aircraft.
Module 6 is on materials and hardware. The topic number 11 is about electrical cables and connectors. Among the subjects covered are...
a. Cables types, construction and characteristics
b. High tension and coaxial cable
c. Connectors types, plugs and receptacles, pins and sockets, identification codes, couplings
e. Current rating
The term cable and wires are used interchangeably to mean the electrical wires.
On completion of the course, I normally gave some quiz. These are the example of the close book quiz...
1. What is/are the characteristics of airframe cable?
2. Why the wire in bundle and protective conduit carries less current compared to the cable in free air?
3. what is the method used to reduce intercable interference in a ribbon cable.
4. What is the different between fire resistance and fire proof cables?.
5. What is the material commonly used a the screen in "screened" cable?
6. What is the range of AWG size of cable used in an aircraft?
7. Name 3 disadvantage of aluminium wires and how does it effect its installation.
8. Silver plating has 2 disadvantages, what are thy?
9. Name the plating used for general aircraft wiring and the high temp cable.
10. PVC is a good insulator, but it has disadvantage, what is it?
The DCAM and EASA had set the number of questions for module 6, inclusive of part 11. It is give in the AN1101 appendix 2.
A 52 questions.
B1 - 72
B2 - 60
Bonus Question... The high tension cable can carry voltage up to 12,000 volts. Explain the construction of wire suited for this.
11. What are the insulators used for Nyvin wire?
12. What the most suitable wires used for general purpose wiring on a turbine engine?
13. Give example and explain the meaning of the wiring code used for circuit identification.
14. What is the common information found in the circuit and cable identification (marking).
15. what are the methods used to mark the cable and circuit markings?
More questions may be generated from module 6 11. In preparing for the module, please remember the syllabus. For example.. cable type. construction and characteristics and I would related to the application. example...
16. What type of wires are suitable to be used in hydraulic contaminated area, how the wire is constructed and what are its characteristics.
17. Draw the structure of the end terminal lug and inline splice and name the parts. Which part hold and crimp the conductors.
18.Draw the coaxial cable and name the part. Which part hold the (BNC) connector?.
19. What are the precaution to be taken to prevent the galvanic corrosion?
20. What are the size range of the AWG wire that can be connected to the yellow inline splice (smaller yellow)?
21. Draw a connector assy, give the names and function of each of the part.
22. State the 3 type of coupling and explain how to connect them.
23. state the two type of pins/socket and explain how to install and remove the pins.
24. Give example of part number of a connector and and the break down meaning of the numbers.
25. Looking at the face of a connector plug with 12 pins, draw the pins, the marked line guide and the parenthesis if any.
The aircraft have advanced tremendously. A system is now installed to support the maintenance works on the aircraft. Most will have the following subsystem:
- Central Maintenance System
- Aircraft Condition Monitoring
- Data Loading and Configuration
The authority like EASA has moved in the same path to include the topic for licensing modules. Enclosed are the syllabus:
12.18 On Board Maintenance Systems (ATA45) Level 2
Central Maintenance Computers;
Data loading systems;
Electronic library system; Printing;
Structure monitoring (damage tolerance monitoring
I include the following extract from A380 pilot's briefing note...
5.6 Basic Computer Structure (Level 2)
(a) Computer terminology (including bit, byte, software, hardware, CPU, IC, & various memory devices such as RAM, ROM, PROM);
Computer technology (as applied in aircraft systems).
(b) Computer related terminology; ( not include for B1 - Level 2 for B2)
Operation, layout and interface of the major components in a micro computer including their associated bus systems;
Information contained in single and multi address instruction words;
Memory associated terms; Operation of typical memory devices;
Operation, advantages and disadvantages of the various data storage systems.
The modern digital aircraft are fitted with Information Systems. For the purpose of licensing, the ATA 46 is included in
A. Module 11. 21.
The breakdown of the content is given below... Level 1 for Category A and Level 2 for Category B1
The units and components which furnish a means of storing, updating and retrieving digital information traditionally provide on paper, microfilm or microfiche. Includes units that are dedicated to the information storage and retrieval function such as the electronic library mass storage and controller. Does not include units or components installed for other uses and shared with other systems, such as flight deck printer or general use display.
1. Typical example include Air Traffic and Information Management System and Network Server Systems
2. Aircraft General Information Systems;
3. Flight Deck Information System;
4. Maintenance Information System;
5. Passenger Cabin Information System;
6. Miscellaneous Information System;
B Module 12.
12.19 Information Systems (ATA46). Level 1 for Cat A and 2 for Cat B1.
You will notice the similar syllabus for both.
The units and components which furnish a means of storing, updating and retrieving digital information traditionally provide on paper, microfilm or microfiche. Includes units that are dedicated to the information storage and retrieval function such as the electronic library mass storage and controller. Does not include units or components installed for other uses and shared with other systems, such as flight deck printer or general use display
Typical example include Air Traffic and Information Management System and Network Server Systems
Aircraft General Information Systems;
Flight Deck Information System;
Maintenance Information System;
Passenger Cabin Information System;
Miscellaneous Information System;
The understand of how the traditional gyro works is important to understand how instruments work. This video explains the two basic property of mechanical gyro, rigidity and precision.
The property of rigidity is used in the directional gyro ( and ADI), Notice that the axis of rotation is horizontal, so the rigidity is in the horizontal plan. If you move in vertical plane, aircraft nose up or down, there is no effect.
The turn and bank is using the property of precession. If a force is applied to the rotating mass, directly or indirectly, the force is taken 90 degree in the direction of rotation.When the aircraft turn, the force it applied through the axis of the gyro and transmitted to the rotating mass. Take note that the axis of the gyro is "Y" axis.
One of the issues, a student of the EASA part 66 modules is the contents definition or the syllabus.The syllabus as defined in the part 66 guide is too brief. Take for example, thee module 12.8 for rotocraft electrical power, ATA 24 is stated in a number of lines, as given below:
12.8 Electrical Power (ATA 24) Level 3
1.Batteries Installation and Operation;
2.DC power generation, AC power generation;
3.Emergency power generation;
4.Voltage regulation, Circuit protection.
6 .Inverters, transformers, rectifiers;
7.External/Ground power. .
Both the students and the training organisation are having too much freedom in interpreting the scope and the depth of the module.
Checking a few established schools in UK, the notes varies from 100 to 220 pages, with different focus and depth.
We had identified the followings as the contents for item 1 : Batteries, installation and Operation...
In module 3, we had
covered the construction of batteries.
In this module 12/11, we
cover on how the battery is installed in aircraft.
We expect the students to
practical installation and maintenance.
operation as intended for the aircraft.
◦ The advantages and disadvantage of different types of batteries. Example, power to weight ratio, voltage stability and cost.
The Flight International reported in 2001 that Airbus has selected Thales Avionics to supply the modules for the A380's integrated modular avionics (IMA). The company is, not surprisingly a French avionics manufacturer and it was working with a Germany company Diehl Avionik Systeme. The other candidate was Smiths Aerospace which supplies the common core system (CCS) for the Boeing 787 Dreamliner.
Works started to assist Airbus to define the concept of modular architecture and develop the system.
The Growth of Data Management in Aircraft.
The term DATA is normally used to describe the elements used in the computing. For the purpose of understanding, I am using it to include the command signals and the advisory signals used in the aircraft. That include the physical commands, like the command to turn left or right nose up or down.
A. Mechanical Linkages
In the days of B707, the term data processing was not coined yet. The command signal from the pilot was transmitted to the control surface via mechanical cable linkages. Some of the position indicators can be operated by mechanical cables. The example is the stab trim. The command can be from the pilot turning the stab trim wheel. The position of the stab trim is given the indicator in the central pedestal. The stab position indicator is driven mechanically by the mechanical cable.
B. Electrical - example stab trip switch.
a. ARINC 429 - Uses 32bits data words to transmit data. It is a simplex system, that mean, data can only move in one direction. A sender can have a maximum of 20 receivers.
D. Federated Architecture
The ARINC 629 gave rise to the Federated architecture. is a multi-transmitter data bus protocol where up to 128 units can share the same bus. It was first installed on the Boeing 777. It is half duplex system, that mean a NOD can transmit and receive data, however it has to do it one at a time, when it transmits, it cannot receive and vise versa.
E. Integrated Modular Architecture.
a. Data processing
b. Data transmission. - ARINC 664 defines the use of a deterministic Ethernet network as an avionic databus in modern aircraft like the Airbus A380, Sukhoi Super Jet 100 and the Boeing 787 Dreamliner. The system is based on the commercial internet (IEEE 802.3). The system is modified to add the deterministic elements as required in aviation. This is required to replace the "best effort" and missing word's packages in the commercial ethernet.
Module 12 is on Helicopter Aerodynamics, Structure and Systems and module 12.8 is on typical helicopter electrical system.
In preparation for the lessons to groups of students, the following will be the topics of the powerpoint presentation. I am not able to include the powerpoint without removing some of the photos which may attract copy right issues.
The syllabus is in according to EASA part 66. The Malaysian version is under AN1101.
12.8 Electrical Power (ATA 24) Level 3
Topics to be covered are...
- Batteries Installation and Operation;
- DC power generation, AC power generation;
- Emergency power generation;
- Voltage regulation, Circuit protection.
- Power distribution;
- Inverters, transformers, rectifiers;
- External/Ground power.
b. The fixed wing aircraft is similar and under the Module 11.6
- Batteries Installation and Operation;
- DC power generation;
- Voltage regulation;
- Power distribution;
- Circuit protection;
- Inverters, transformers.
2. About Module 12.8 or 11.6
The electrical power system will always consists of 3 elements:
To suit the adult learning preferences, I always give the students the overview.
The traditional chalk and talk is used to suit the various levels of the students. Free white board drawing on the following topics.
- Brief Overview of parallel system
- Overview of DC System
- Main Components
- Generators – AC and
- Voltage Regulator
- DC generator
- Circuit breaker
4. . Battery Installation and Operation
In module 3, we had covered the construction of batteries.
In this module, we cover on how the battery is installed in aircraft.
We are expected to know:
- Safety practices
- The practical installation and maintenance.
- The operation as intended for the aircraft.
- The circuit diagram
- Types of Batteries
- Lead Acid
- Nickel Cadmium
- Lithium Ion
5. Battery Connector
A quick release connector with copper lockwire 26 AWG.
Contacts to be lubricated with white petroleum jelly to prevent corrosion.
6. Temperature Monitoring - The importance of temperature monitoring. The description of thermal runaway.
- the various methods to ventilate, the importance of ventilation especially for lead acid battery.
8. Lead Acid Charging
- Indications of fully charged cells
- On charge – 2.7 volts => x12 = 32 volt.
- SG maximum
- Indication of fully discharged
- Voltage 1.8v
- SG minimum
9. Servicing – Lead Acid Battery
Lead Acid Battery
No servicing allowed.
Considered serviceable if the voltage (charger off) is above 24 volts.
10 - Advantages/Disadvantage NiCd
- The Advantages are Better power to weight ratio, Lower internal resistance, Longer life, Easy to replace cell, More robust and Higher Charging rate thus shorter charging time. Wider operating temperature
- Disadvantages are Higher cost, Prone to thermal runway and it Requires complex charging control circuit.
11. Battery Capacity
Understand how capacity is measures and the effect of discharging rate on the capacity calculation.How the capacity is measured.
The new digital avionics used on the latest aircraft require the understanding of computer networking. For that purpose, I am including this video for my learning of TCP IP.
I find the graphic and animations used to explain TCP IP very informative..
The video gives a graphical presentation of how the data is being sent from a computer to another destination. If your are sending a set of data to a receiver, you computer will break your data into smaller packages. Each package will have a number of information attached plus the contents. Some of the compulsory information are...the sender address, the receiver address, proxy server address. If you are sending from your office, it is likely that your data will enter the local area network. and then it will be sorted by the proxy server.
Understanding the basic computer networking is a must for a person to understand the AFDX in an aircraft. For that reason, I had embarked in a journey to learn about networking.
We know that the data sent through internet packages, each has the addresses of sender and receiver.
To enable the different computers understand the messages, in 1970's - ISO formulate the standard OSI model - the open system interconnection.. The network is in 7 layers:
application, presentation, session, transport, network, data link, physical.
In order to remember, take the first letters of the words, and you will have... all ... people seem to need data processing.
The Function of The Layers
application layer -deal direct with the user. When you have something to send, the application layer will say... "hai, I have something to send".
- presentation layer will format the things that you want to send.
- session layer - syncronisation so the sending and receiving syn
- transport layer - manage the package, data when sent are broken into packages
- network - routing and addressing, like ip addressing.
- data link - data frame management, the actual packaging, putting into the proper envilope.
- physical layer is the actual hardware.
When you are receiving the information, the path is reversed. It start with the physical layer.
How Data is sent and received
As it move down, information is being added to the data. On the receiving side, the wrapper is unrapped layer by layer, until the pure data is read.
TCP IP Model
It is based on DARPA model with 4 layer of data.
In my efforts to learn about the Integrated modular avionics face challenges, as most of the references in the internet assume that the reader understand the basic computer networking. We may come across comments stating that "the new AFDX is using is ethernet based" system. Thus, understanding the basic of computer networking is necessary to understand intergrated modular avionics.
I begin my search at the history of internet...
The history of ethernet began with Mr Xerox corporation in 1973, devising a system to connect its laser printer to multiple computers.
It is package data communication.
74 - PC was connected to the co-ax cable to communicate with other computers.Out of their own creativity the co-ax cable was called 'ether'. This was how the name ethernet was coined.
79 - Effort to manufacture ethernet compatible products.
80 - Promote ethernet as the standard communication network for PC. Compete with IBM, who promoted token ring.
89 - Ethernet won the battle when they switched the cabling standard to UTP.
The speed had brown tremendously, this was how it started:
- Started as 2.98 megabytes
- 10Base T - 10 megabyte per sec using the UTP
- 100 Base T - 100 megabytes
- 1 Gig
- 10 Gig
Knowledge of internet is necessary as aircraft are using the concept and the technology in the data communication.
I have chose a simple and short Youtube video to give the basic understanding of the working of the internet. I am also putting information on ethernet, the basis of the AFDX, used on A380.
I like the simplified concept where the internet is considered to be a wire to which your computer is connected. There are many computers and networks that are connected to these wire where you can access them. Each of the items connected to the internet wire are given an IP address such as 188.8.131.52. These addresses are made more human friendly by giving them a suitable names known as domain names.
A personal users like me will connect by computer to the internet through an ISP, Internet Service Provider. By searching through the address, I will reach the domain that I want to gain access.
This concept is used in the aircraft communication although the protocol and the control may be different.
The MIL 1553 standard was published in 1973 to provide the functional characteristics of a serial bus. It was first used by F-16 Falcon followed by a number of other military aircraft. It is a half duplex system with redundant cables.
To understand how the system work, we need to understand some of the terms:
- Avionic bus – communication between diff parts of ac
- Source – remote terminal with data to transmit
- Sink – a remote terminal to receive the date
- Dual redundancy - use
of back up system even part of comm. Fail, data will be sent and received.
2. Development on the EARLY aircraft.
-One device one display
-No crss communication.
-Example, altimeter, speedometer and compass are
-One devices many users.
oAltimeter – display/ autopilot/ flight recorder.
oEngine parameters – display/ autopilot/ flight
data recorder/maintenance log.
1980 ARINC 429, direct wire connection. As long the number
is small, the system work well.
3. About MIL 1553
- Communication between 32 boxes.
- Data 32 16 bits words
- Command control , commander speak one at a time, all tramits
begins with command word.
- 0 BC to all RT
- 0 Broadcast BC to all RT
- 0 RT to BC
- 0 Housekeeping messages (mode codes).
- Message format:
- 0 Command word from bus controller
- 0 Data from RT to/from bus controller
- 0 Status word from RT
0 The 5 bits address can only support 32
The T/R bits will determine receiving or
transmission mode, 1=transmit and 0 = receive data