Sunday 15 December 2013

COMMAND SIGNAL DETECTION

COMMAND SIGNAL DETECTION
Chapter 4  COMMAND SIGNAL DETECTION
 Automatic Flight Control by E.H.J Pallet & Shwan Coyle.


Signal & Sensor

Electrical command from Pilot to Control Surface or A control Surface's respond in the form of voltage is call command signal And the sensors which detects are call command signal sensor & transducer.
These sensors are of inductive type and works on the basis of transformer  with fixed primary winding & variable secondary wingdings.

Types of command signals:

There are followed type of these inductive type command signals sensors

1) E & I Bar Sensor
2) Moving  vane Sensors
3) Synchros

E & I Bar Sensor:

This is and inductive type sensor used for position attitude changes.The AC signal is applied on Center limb of 'E' when there is defection in 'I'
this shows that there is an attitude changes in respective control surface with this E&I bars sensor is coupled.And if there is no deflection means
the control surface has maintained it leveled position.



Moving Vanes Sensors

This inductive type sensor is also used for attitude changes with their respective steering gyroscope.
The two sensor are used.One is having its vane in the inner gimbals of gyro for pitch attitude where as the other is having in the outer gimbals for roll attitude sensing.
The AC signal is applied on the 1 and 3 ends of the sensor with 180 degree phase shift.
If the vane is at the center position 2 this means that the aircraft is at level flight.if the vane is varied between the 1 & 2 or 2 &3 then it means
there is and attitude change with respective control surfaces.
 

Synchros

The synchronous self inductive type signal detectors are called synchros and are of type:

1) Torque Synchro
2) Control Sysnchro
3) Differential Synchro
4) Resolver

Torque Synchro: This is used for a very small movement in aircraft.This is use to detect angular position.And in instruments
On transmitting end (TX) its had generator and generating shaft whereas on receiving End (TR) it had AC motor.


 
Control Syncho: This is used to detected the signal from large movements such as control surfaces.It has same function as torque but there is a Transformer on Receiving end (CT).


Differential Synchro: The synchronous signal detector that uses the error difference between two angular position us called differential synchro.Its uses TDX/CDX in between
Torque and Control Sysnchro and the  symbols are given as:


Resolver: An interesting sysnchro that converts cartisan co-ordinates systems to Polar Co-ordinates and vice versa is called Resolver.


Friday 13 December 2013

Amazing Information

Amazing Information

  (Chapter11) of Automatic Flight Control by E.H.J Pallet & Shawn Coyle

--Fly by wire is the concept that provide effective computer link between the
pilot control and control surface.

--This concept was implemented first in Concorde(elevon control)
& Boeing 767 for its wing control spoilers.

-- Airbus A320 was the only plane which FBW was designed for.

--  The increased effectiveness by Side-Stick(*1) Control column

Advantages of FBW Control System:

1) Weight Saving
2) Reduced Maintenance Time
3) Gust Load Alleviation
4) Automatic Manoeuvre  Envelop Protection
5) Improved Handling
6) Fuel saving

(*1) Side Stick Control Column id the replacement of Control Column/Wheel Control Column.
     A light weight control stick Which is fixed by Pilot Arm in Cockpit                        

 Architecture of FBW

In advacne FWB Conrol System There are two basic termonologies are used
such Arcitecture & Conrol Laws.This system is also called actvie control system.

Architecture

The genaral Layout of the components such as computers and thier function are
called architecture.These copomuter are working with redundancy to inhance the stability
and the less failure system
In A320 there are seven operational computer working with ARINC 429
DATa Bus in communication among them and listed as under

1) ELACs Elevator/Aileron Computer   (2)
2) SECs  Spoilrer/Elevator Comouter  (3)  
3) FACs  Flight Augmentation Computer(2)

Control Laws

The maanner in which the operational computers are expected to control the control surfaces are called Colrol Laws
Keeping in mind the conpcet of redundancy & the safety factors  these conrols law are listed as under with there respective comuters

Normal Conrtol Law    ---ELACs
Alternate Conrol Law  ---SECs
Direct Control Law    --Strick to Elevator/Direct Control
Mechanical Backup     --Mechanical Link to the Pitch Trim

Special C-Star(C*) Control Law:

C* is the special type of Pitch Control Law which has much acceptance in commercial airlines.
This is a flight path command control law even at low speed including pitch command rate.In general the pilot is
able to select a particular flight path with particular angle such as level flight.Once this particular flight path with angle is
achieved then if Pilot releases the control stick this law ensures that that particular angle is retained
By introduction of pitch ate command this helps us to overcome Lags& over pitch activity allow speed and in flare mode at 50 ft above the
ground.

Answers Ref-1


Answers Ref-1


Chapter 10

Q1) What are the fundamental requirements of Automatic landing? 

In order to achieve safe landing the aircraft has to be So controlled that:
1) its wheels should touch the ground comfortabliy
2) its should be within the paved surface of the runway
3) its should be with in the longitudinal limits
4) its sinking speed should not be greater than 1/2 ft/sec
5) its touch-down speed should be greater 30% of stalling speed
6) Wings should be levelled prior to the actual landing
7) its should be yawed to bring is longitudinal axis parallel to the center line of runway
8) its de crabbing or Kick-off man-oeuvre should be removed

Q2) What is the minimum accident of acceptance in UK-CA?

According to United Kingdom Certification Authorities A system should not cause fatal accident more often than one million landings.

Q3) What is weather minima and its parameters?

In low visibility condition the weather limits for londing its called weather minima & its parameters are
Runway Visual Range(RVR) & Decision Hight(DH). 

Q4) What is "Sland Visual Range (SVR)"?
The factor in which the pilot must take an account or makes sure everything to avoid any misinterpretation of visual cues

Q5) What are ICAO categories of Landing.Give name & Ranges?

There are three categories of landing defined by ICAO and given as under:
Category 1 (RVR should & DH should be minimum 800m & 200 ft Respectively).
Category 2 (RVR should & DH should be minimum 400m & 100 ft Respectively).
Category 3A (RVR should & DH should be minimum 200m & 50-100ft Respectively with external NavAids).
Category 3B (When the taxiing operations is visible at 50ft DH with external NavAids).
Category 3A (When the taxiing operations is visible on runway at 50ft DH without external NavAids)

Questions

Questions Ref-1

Q1) What are the fundamental requirements of Automatic landing? 
Q2) What is the minimum accident of acceptance in UK-CA?
Q3) What is weather mini-ma and its parameters?
Q4) What is "Slant Visual Range (SVR)"?
Q5) What are ICAO categories of Landing.Give name & Ranges?

Please find the answers of if Ref-1 in 'Flight Control System'.Click Above. 

Thursday 12 December 2013

Hierarchy of Autopilot

Hierarchy of Autopilot

Papers----------




I have shared all the information from Chapter 11 of our Book ADC by  E.H.J Pallet in bullets(Note a single information is missed).Just give one glance & Chapter is Done... Just Click on  "Flight Control System" Button in my blogger above

A picture of FBW Control System


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