DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
İZMİR INSTITUTE OF TECHNOLOGY
SUMMER PRACTICE REPORT
IN
[TAI]
SUBMITTED TO: [Zübeyir ÜNLÜ]
SUBMITTED BY: [Mustafa Can AKBAŞ,150206013]
[Summer, 2011]
1
TABLE OF CONTENTS
1)DESCRIPTION OF THE COMPANY.………………………………….………………..3
Company Name………………………………………………………..….….……………....3
Department Name………...……………………………...……………….….………………3
Company Location……………………………………………………………….…....…......3
Organizational Structure of the Company……………………………………………….......3
History and Main Area of Business of the Company………………………………………..4
Total number of working days of training……………………………………...……………6
2)INTRODUCTION…………………………………………………...…………………….7
3)LIST OF TASKS…………………………………………………...……………………...7
4)BODY OF THE REPORT…………………………………………………………………8
4.a) Briefing and the Factory Tour.…………………………………………………………..8
4.b) Informed about what FTI group do…………………………………………………….11
4.c) Introduction to Avionic Systems Education ……………………………………...……15
4.d) Informed about Data Acquisition, Calibration and Measurement Processes ………… 16
4.e) Software Engineering Education ………………………………………………………17
4.f) Informed about Avionics Data Buses …………………….…..…….………………….18
5)CONCLUSION……………………………….……………….………………………….20
References…………………………………………………………………………………...21
2
1)DESCRIPTION OF THE COMPANY
NAME OF THE COMPANY
TURKISH AEROSPACE INDUSTRIES INC.
NAME OF THE DEPARTMENT
AVIONIC SYSTEMS-FLIGHT TEST INSTRUMENTATIONS
LOCATION OF THE COMPANY
Fethiye Mahallesi, Havacılık Bulvarı No:17
06980 Kazan-ANKARA / TÜRKİYE
ORGANIZATIONAL STRUCTURE OF THE COMPANY
3
HISTORY AND MAIN AREA OF BUSINESS OF THE COMPANY
TAI was established on 15 May 1984 in Ankara, Capital of Turkey. The Turkish Armed
Forces Strengthening Foundation, the Undersecretaries for Defence Industries and the Turkish
Aeronautical Association are TAI's shareholders. TAI aimed to improve Turkey's national
power since it was established.
In TAI, co-production of
F-16 fighters, CN-235 light transport, maritime patrol,
surveillance aircraft, SF-260 trainers, Cougar AS-532 search and rescue (SAR), combat
search and rescue (CSAR) and utility helicopters as well as design and development of
unmanned aerial vehicles, target drones and agricultural aircraft is among the products which
is in modernization or production. Furthermore, TAI is the prime contractor of the Turkish
Unmanned Aerial Vehicle (MALE) and the Turkish Armed Forces Attack Helicopter
production program. Also it is continuing designing and development working of Primary &
Basic Trainer (HÜRKUŞ) Aircraft.
152 F-16C/D aircraft was manufactured and delivered to the Turkish Air Force under
the Peace Onyx I Program between 1987 and 1995 80 F-16C/D aircraft to the Turkish Air
Force under Peace Onyx II Program between 1995 and 1999 and 46 F-16s to the Egyptian Air
Force under Peace Vector IV Program between 1993 and 1995. TAI also produced 34 SF260D primary trainers for the Turkish Air Force between 1991 and 1993 with AGUSTA of
Italy. TAI produced and delivered 50 CN-235 light transport aircraft to the Turkish Air Force
between 1991 and 1998 and six CN-235 Surveillance Aircraft for the Navy Command and
three CN-235 Maritime Patrol Aircraft for the Coast Guard Command between 1998 and
2003 with CASA of Spain. 30 Cougar AS-532 helicopters , 20 of whom is for the Turkish Air
Force and 10 of whom is for the Turkish Land Force were produced between the year of 1997
and the year of 2003.
There are a lot of modernization, modification and systems integration programs in TAI
and its core business also includes after sales support of both fixed and rotary wing military
and commercial aircraft that are in the inventory of Turkey. Electronic warfare retrofit and
structural modifications on TuAF F-16s, modification of the S-2E Tracker Maritime Patrol
Aircraft into Fire Fighting Aircraft, Black Hawk modifications for Special Forces,
modification and modernization of Cougar AS-532, Glass Cockpit Retrofit of S-70
helicopters, modification of CN-235 platforms for MPA/MSA missions for the Turkish Navy
and Coast Guard, the modification of ATR-72 platforms for the Turkish Navy as well as
4
structural modification and systems integration activities required for the conversion of B737700 aircraft into AEW&C aircraft are major programs of TAI. Furthermore, TAI is the prime
contractor of the Erciyes program, which comprises the avionics modernization of C-130
aircraft that are in the inventory of the Turkish Air Force Command.
TAI is a qualified supplier for AgustaWestland, Airbus, Boeing, CASA, Eurocopter,
Lockheed Martin, Northrop Grumman, MDHI, Sikorsky and many more. TAI manufactures
sections 18 fuselage panels for Airbus A319/320/321 aircraft, wing tips and flight deck panels
for Boeing 737 aircraft, rear doors and engine cowlings for Eurocopter EC-135 helicopters,
horizontal stabilizers, tail rotor pylons and tail booms for Sikorsky S-70A and MH-60
helicopters, horizontal stabilizers for S-76 helicopters, MD-902 fuselages for MDHI and
AB139 fuselages for AgustaWestland. Moreover, TAI manufactures nose landing gear doors
for B747, Dorsal Fin for B777 and parts/subassembly parts of B737/767/777, wire harness
assembly for B737, piano panel parts for B777, and it also produces seven components of the
Cougar AS-532 helicopters. The center fuselage of Joint Strike Fighter (JSF) - F-35 aircraft
will be manufactured at TAI's facilities from February 2007.
To develop the Turkish Unmanned Aerial Vehicles program is among TAI’s miissions.
With the locally productions of MARTI, KEKLİK, TURNA/S, TURNA/G, GÖZCÜ,
PELİKAN and BAYKUŞ, TAI, which has gained experience in UAV technology, became
dominant in integration of subsystems to the platform.
Determined to follow global technological developments and be among the major
aerospace companies, TAI aims to be a leader of Turkey in aviation area in the 21st century.
TAI'S VISION: In the 100th anniversary of the Republic of Turkey; TAI, by possessing
indigenous/co- designed aircraft and satellites; seizing modern high technologies in
modification, modernization and production, and attaining global competitive power, will
become a world brand company with its devoted employees.
TAI'S MISSION: With our great leader Ataturk’s vision: "The Future is in the Skies"
and our nation's eagerness to "Build its own aircraft"; TAI has dedicated itself to be in the
skies and space and be pioneers in developing Turkey's aviation and space industry.
Projects of the company are in three groups which are; Aircraft Projects, Aircraft
Components and Satellite Projects, Helicopter Projects.
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Capabilities
•
Design and Engineering
•
Tool design and manufacturing
•
Machining, tubing, welding and sheet metal fabrication
•
Composite and metal bonding
•
Electrical assembly
•
Maintenance, repair and overhaul
•
Integrated product support
•
Quality systems
•
Quality assurance
•
Information technologies
•
Training
Total number of working days of training
20 working days between 11 July and 5 August
6
2)INTRODUCTION
This summer practice aimed to be getting introduced with the business life, being
prepared to events that will happen in the future and adaptation to the working day; wake up
at 6:00 AM, start working at 7:45 AM and working until 5:30 PM with only a break time. In
addition to these, one of the main purposes was doing practices about the courses we learned
in IYTE. According to the these aims I tried getting close to engineer.
In my summer practise, I was interested in testing avionic equipments in Flight Test
Instrumentations department. Moreover, the engineers in my department was very helpful to
me. They give me some subjects to research about avionic systems. While I gave datas and
test results of the machines and also with the engineer’s helping to me, I felt like an engineer
in TAI, not an inturn.
3)LIST OF TASKS
Date
Task description
11.07.2011 - 13.07.2011
Briefing and the Factory Tour
14.07.2011 - 22.07.2011
Informed about what FTI group do
25.07.2011
Introduction to Avionic Systems Education
26.07.2011 - 29.07.2011
Informed about Data Acquisition, Calibration and
Measurement Processes
01.08.2011
Software Engineering Education
02.08.2011- 05.08.2011
Informed about Avionics Data Buses
7
4) BODY OF THE REPORT
4.a) BRIEFING AND FACTORY TOUR
4.a.i) My task was attending to educations and seminars given by TAI and making
factory tour with other inturns.
4.a.ii) Training took 2 days and the factory tour took 1 day.
4.a.iii) I think this educations aren’t interested with IYTE courses because these are
factory educations.
4.a.iv) I learned a lot of things about factory rules and concepts, business health and
safety and FOD and ESD.
4.a.vi) This task is compulsory in TAI to work as an inturn or an engineer.
In my first day, I went to sports hall in TAI fot orientation and firstly they controlled our
names. They had also wanted some documents for the security. We gave the documents and
lined up in sports hall and waited for getting identity cards. After getting identity cards, there
was a presentation about TAI’s history and working areas, rules that must be obeyed by
engineers and interns and about the application contidions for employment in TAI, privileges
provided by TAI to employers. There was a briefing about the Business Health and Safety
subject, FOD and ESD on Tuesday. We learned about factory safety concerns. On
Wednesday, we learned the department. My department was Avionics Systems. After learning
about avionics systems it’s wanted from us to choose a department to work with. I had wanted
to work at Flight Instrumentations Department and it was accepted. Finally I arrived our
section and get acquainted with the engineers in our section.
BUSINESS HEALTH AND SAFETY
TAI gives some important knowledge about business health and safety and wants every
workers to take this education preventing the work accident.
This education provide a positive health and safety culture to employees, meeting the
legal duty to protect the health and safety of employees and finding out how they manage
health and safety better.
8
FOD (Foreign Object Damage)
Foreign Object Damage or Foreign Object Debris (FOD) is a matter that has potential to
cause damage to a vehicle or system. A foreign object can extremely be hazardous to plane or
any kind of machine. It may causes planes blow up while flying. This may results loss of
billion dollars to industry and also deaths. FOD costs the aerospace industry $1.1–$2 billion
USD per year in direct costs, and as much as ten times that amount in indirect costs from
delays, aircraft changes, incurred fuel costs, unscheduled maintenance, and the like for a total
of $12 billion USD per year.
Some FOD reasons:
• Dust comes from the air
• Broken machine parts
• Forgotten tools or excess wire parts while constructing plane
• Birds
Examples to FOD:
Air France Flight 4590
The crash of a Concorde, Air France Flight 4590, at Charles de Gaulle International
Airport near Paris on 25 July 2000 was caused by FOD; in this case a piece of titanium debris
on the runway which had been part of a thrust reverser which fell from a Continental Airlines
McDonnell Douglas DC-10 that had taken off about four minutes earlier.
[4]
All 100
passengers and nine crew on board the flight, as well as four people on the ground, were
killed.
9
US Airways Flight 1549
US Airways Flight 1549 was a scheduled commercial passenger flight from New York
City to Charlotte, North Carolina, that, on January 15, 2009. Plane ditched in the Hudson
River adjacent to Manhattan six minutes after departing from LaGuardia Airport.
ESD (Electrostatic Discharge)
Electrostatic discharge (ESD) is the sudden and momentary electric current that flows
between two objects at different electrical potentials caused by direct contact or induced by an
electrostatic field.
People can carry about 10000V static voltage on. This high difference makes body
discharge sparks to integrated circuits or boards. There are also devices affected by small
electrical discharges about 10V. A spark is triggered when the electric field strength exceeds
approximately 4 - 30kV/cm, the dielectric field strength of air. In that case air becomes an
electrical conductor and allowing free electrons and ions pass through and this phenomenon is
called dielectric breakdown.
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4.b) INFORMED ABOUT WHAT FTI GROUP DO
4.b.i) My task was to be informed about FTI GROUP works
4.b.ii) 7 work days
4.b.iii) I think IYTE educations contribute me while studying how FTI groups take the
measurements. Circuit Analyze and Laboratory lessons help me when I was learning about
FTI group works.
4.b.iv) I learned a lot of things about department, what FTI group do.
4.b.vi) I think this task is important to recognize the department which you work.
Note: For strict security reasons I could only give some space just headings of some job I
involved in.
FTI GROUP
TAI has many sub-divisions. Flight test instrumentation (FTI) group is one of the
important ones. Group’s responsibility is to make:
• Design of required on-plane test instrumentation
• Provide test instrumentation
• Integration and implementation of test instrumentation
• Transformation of acquired data
• Confirmation of acquainted data
In short, FTI Group performs required test instrumentation for the on-plane tests. Job of
instrumentation design is carried out by taking account of some parameters:
• Choosing appropriate sensor
• DAQ system/card, signal conditioning
• Filter necessities
• Sampling rate
• Appropriate data record device and record capacity
• EMI/EMC necessities
• Power necessities
• Localization necessities
• Environmental factors
• Data transfer rates
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Capabilities:
• Vibration measurements
• Temperature measurements
• Avionic confirmation instrumentation
• Strain-Gauge measurements
• Force-Torque measurements
• Air-data system measurements,
• Electrical system measurements and etc
During my summer practice, testing department demanded some jobs. One of them is
about being able to use a data acquisition tool with MATLAB software by its DAQ toolbox.
My duty was to establish a connection with DAQ device via Ethernet and sending sampled
sinusoid waves to observe analog ones of them from one of its outputs. Also I took place in a
paratroopher door test. It was about measuring strain and force on the door in order to finalize
design.
Toolbox has commands helping in finding devices via computer’s connections. We can
create analog and digital I/0 adaptors for configuring DAQ devices. Sampling rates and
triggering is adjustable for engineer’s needs.
For instance:
AO = analogoutput('winsound',0)
chan = addchannel(AO,1)
Æ
Æ
opens analog device.
adds one channel to device.
set(AO,'TriggerChannel',chan(1)) Æ set commands help us to adjust properties of our devices
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AVIONICS ELECTRICAL SYSTEMS
A plane has composed of there systems:
• airframe
• utility and
• avionic systems
First power systems are engines of plane. They provide impulsion for thrust which
makes plane fly. Lift, weight and drag forces are consequences thrust and plane itself.
Auxiliary power systems are compressed power and shaft power when enginees are
running and battaries, ground carts and ram air turbines even before actuation They are
seperated into three forms:
• Pneumatic (use of pressurized gas to affect mechanical motion) power system
• Hydrolic power system and
• Electrical power system
They also named as APU (auxiliary power unit), in short, whose main purpose is to
provide energy for functions other than propulsion.
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POWER SYSTEMS
These systems composed of DC and AC systems. Generally 28V dc is used on planes;
but some use 270V dc. The difference between two choices above is cable weight of plane.
For instance, a 280W heater allows about 1A current pass through for 270V dc system, but in
28V dc’s it is about 10A. The Ampere passing though cable massively effective on its length.
There are applications which uses currents up to 400A and channels having capacity of
12KW in 28V systems.
Nowadays brushless electric motors are on outrun because of
expensive brush checkings. They are more efficient and reliable with overall reduction of
electromagnetic interference (EMI), more power, longer lifetime.
Figure 5 [9]
AC power systems are produced as 3 fhased 115Vac. In general, constant frequency in
AC systems is 400Hz. IDG (Integrated Drive Generator) produces that output. During flight a
plane flies with its 60 or 100 percent of speed. Plane needs to produce a constant power to
carry on its flight. CSD (constant speed drive) that is basically the transmission component of
the IDG which is made up of the CSD and the generator, stabilizes output rpm to produce 400
+/- 20 cycle operation.
System is also composed of transformer rectifiers (AC to DC) and Inverters (DC to AC).
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4.c) INTRODUCTION TO AVIONIC SYSTEMS EDUCATION
4.c.i) Task is to participate to the education.
4.c.ii) The education took 1 work day.
4.c.iii) IYTE lessons are not related to Avionics Systems. I learned about avionic
systems in this education in TAI.
4.c.vi) I learned briefly Avionics Systems. I recommend other students to attend the
Avionics Systems Education, if they are interested in aircrafts and its avionic systems.
Yasin Kaygusuz telled about the definition of avionic systems and the history of avionic,
architectures, cockpit. After these informations, Soner Uyar explained the radio systems on an
aircraft and Tolga İnan explained about recording control systems.
Avionic is the combination of two words, aviation and electronic: Avionic = aviation +
electronic. It comprises electronic systems for use on aircraft, aircraft satellites and spacecraft,
comprising communication, navigation and the display and management of multiple systems.
In this training, I have learned main components of avionic system and also learned that
avionic systems can be categorized, and main categories are aircraft avionic, mission avionic,
aircraft network. In this scope, it is indicated that the avionic systems are essential to enable
the filght crew to carry out the aircraft mission safely and efficiently. Even on an aircraft in
general aviation category, the avionic equipment is now relatively significant and can be in
the region of %10 of the total cost of an aircraft.
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4.d) INFORMED ABOUT DATA ACQUISITION, CALIBRATION AND
MEASUREMENT PROCESSES
4.d.i) My task was to be informed about data acquisition, calibration and measurement
processes.
4.d.ii) 4 day
4.d.iii) I think IYTE courses became useful while measuring and acquiring datas.
4.d.iv) I learned how to acquire datas, why calibration is necessary.
DAQ is acquiring electrical signals representing data gathered from real world
phenomena by using sensors and some kind of electrical instruments. Data is usually in digital
format. Any stimulus is convertible to electrical signals with appropriate sampling rates, for
instance, pressure, strain, force, vibration, light, heat, etc.
Testing instruments are based on acquiring data. FTI (Flight test instrumentation) Group
uses sensors provided from vendors with their software to process data and some
programming languages for representing results in a meaningful way.
Test instruments require calibration before any preparation. It is the first thing to do. It’s
the act of checking or adjusting (by comparison with a standard) the accuracy of a measuring
instrument. Process requires two devices: a calibration device providing required standards
and the unit under test (UUT).
Devices used for testing must have very high sampling rates in order to catch
instantaneous changes and be flexible, because various testing processes may require high
expenses for devices, for the kind of tests.
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4.e) SOFTWARE ENGINEERING EDUCATION
4.e.i) My task was to attend to software engineering education
4.e.ii) It takes 1 day
4.e.iii) I think IYTE courses are not related with this education.
4.e.vi) This education is important to know what software is and what is necessary to
make a good process in software,and I recommend attending this education to the other
students.
Software systems were designed for completing some tasks in computer systems.
Software can be defined as an interface between the problem domain and the solution domain.
There are some properties for the high quality in software. These are maintainability,
reliability, efficiency, stability and usability. Changings according to the needs of the
customer, can be provided by maintainability. The reliability is the property that is working of
software as expected in the particular time interval. Reliability is determined by Mean Time
Between Failure. One of the efficient properties of the software is efficient usage of the
system sources as like memory and processor by the software. Safety is determined by a
threshold. The other property, usability, is having enough document and user interface. Acting
conceivably in unexpected case is also the property of software. This is the stability property
of the software.
To obtain a good software work, it is necessary to be careful while applying software
development process. Software requirement specification, software design, code, test and
integration is important in the process. Being accurate, coherent, precise and testable is
necessary to get a high quality software.
There are some methodologies while processing of software.These are Cascade Model,
V Model, Spiral Model, Evolutionary Development, Prototype Model, Evolutionary
Prototype, Incremental Development.
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4.f) INFORMED ABOUT AVIONICS DATA BUSES
4.f.i) My task was to be informed about avionics data buses
4.f.ii) 4 day
4.f.iii) In my opinion, IYTE courses are not related with this education.
4.f.vi) This education is important to know which data buses are used in measuring and
acquiring.
WHAT MAKES AN AVIONIC BUS?
The important factors of avionics buses include:
Deterministic behavior, Fault tolerance, and Redundancy. Most avionics buses are serial
in nature. A serial bus using only a few sets of wires keeps the point to point wiring and
weight down to a minimum. MIL-STD-1553 (rev B) is the best known military example,
having been developed in the 1970s. The trend seems to be moving to Fiber buses, MIL-STD1773 being the fiber version of 1553. Switched fabric networks are used to provide Fault
tolerance. [1]
INFORMATIONS ABOUT BUS STANDARDS ORGANIZATION
The US Military uses terms like MIL-STD-xxxx (Military Standard-"Doc #"). The
United Kingdom (UK) uses DEF-STAN-xxxx (Defense Standard-"Doc#"), NATO calls their
specifications STANAG (Standard Agreement). In some cases US military standards are
transferred to a commercial standards agency for control. In these cases the military standard
is retired and the document takes on the name of the commercial agency. In the case of the
1553B bus, the name changed from MIL-STD-1553B (US government standard) to AS
1553B (SAE standard). Aeronautical Radio inc. produces many of the commercial avionics
standards, termed ARINC #. Of course the IEEE or ANSI controls many bus standards.
There are busses specific to test & instrumentation section bonded strictly to standards
those above. And they are just some of busses used by TAI. [1]
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Commercial used bus: ARINC 429
• Digital Information Transfer System
• Point-to-point, 2-wire Bi-Polar Return-to-Zero signal
• 32 bit data.
• 100K or 12.5K bit rate
Bus may use Williamsburg Protocol, which transferred blocks of data. It’s similar to
ARINC 575, but being replaced by 629. [1]
MILITARY USED BUS (MIL-STD-1553)
It’s a DOD Military (MIL) Standard (STD), which defines both the Mechanical,
Electrical, and Functional characteristics. MIL 1553 uses a Balanced (Differential) interface.
The interface is dual redundant with between 2 and 32 interface devices on the bus.
Communication over MIL-STD-1553 is half-duplex at a speed of 1Mbps using 75 ohm
copper wire cable.
NATO calls MIL-STD-1553B: STANAG 3838AVS; the UK calls it DEF STAN 00-18.
Now controlled by the SAE as AS15531, and re-released by NATO as STANAG 7155. [1]
Digital Data Busses and MIL-STD-1553. [12]
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5)CONCLUSION
My summer practise was about testing avionics equipments on aircrafts before flight. I
was interested in these avionics systems during the summer practise. It was very good and
nondescript experience for me. Furthermore, being in TAI as an inturn was also very useful
thanks to TAI’s helpful engineers. I think TAI is a world brand company with its devoted
employees in Turkey and it gives a lot of opportunities to engineers to work more efficiently.
After being with these engineers, i want to be a member of TAI. Even if it is exhaustive to
work in this company, I want to be and work there because of these good conditions of TAI.
In my summer practise, I have learned so many things about factory structure, avionics
systems, jobs doing by electronical engineers in TAI, data acquasition, testing types before
flight. We were informed about working areas of electronical engineers and almost everything
which can be necessary while working.
During the summer practise, i woke up at 06:00 Am, I started to work at 07:45 Am and I
finished working at 17:30. There was a break time between 12:15 and 13:15. Except this
break time, I was in the office and testing area in the factory. We were also tested avionics
equipments on C-130 aircraft and learned so many things about this equipments’ working
modes. All the devices were produce of modern technology. I researched also Data
Acquisition, Calibration and Measurement Processes and Avionic Data Buses and learned so
many things about these subjects.
I think the tasks i have done in TAI are sometimes related to lessons in IYTE. Circuit
Laboratory Lesson was become useful during the summer practise. I used oscilloscope,
measured power.
As a consequence, i am happy to be as an intern student in TAI. TAI has so
many division and sections and it has got working areas for an electronical engineer. If
you are also interested in aircrafts, working as an engineer or an intern in TAI is undefinable
happiness. I recommend it to other students for summer practice or as an engineer in the
future.
20
REFERENCES
1
Davis, Leroy. December 19, 2008.
http://www.interfacebus.com/Design_Connector_Avionics.html
2
“According to the National Aerospace Standard 412”. National Association of FOD
Prevention, Inc.
3
“The Economic Cost of FOD”. Insight SRI Ltd. November 28, 2008.
http://insightsri.com/publications
4
“Foreign-Object Damage Cripples Concorde on Takeoff from Paris”. Flight Safety
Foundation Accident Prevention. April 2002. http://www.flightsafety.org/ap/ap_apr02.pdf
5
“Live Flight Track Log (AWE1549) 15-Jan-2009 KLGA-KLGA”. Flightaware.
January 15, 2009.
http://flightaware.com/live/flight/AWE1549/history/20090115/2026Z/KLGA/KLGA/tracklog
6
US Military Handbook DOD-HKBK-263
7
CRC Handbook of Chemistry and Physics
8
wrdnet.princeton.edu/perl/webwn
9
“[JSAP] Tokai University Unveils 100W DC Motor with 96% Efficiency”. Nozawa,
Tetsuo. Nikkei Electronics. Apr 3, 2009.
http://techon.nikkeibp.co.jp/english/NEWS_EN/20090403/168295
10
http://www.tai.com.tr/
11
http://www.elec-intro.com/mfd-simulator
12
http://www.altadt.com/support/tutorials/mil-std-1553-tutorial/
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