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ISSN : 0971-4413
BULLETIN OF DEFENCE RESEARCH AND DEVELOPMENT ORGANISATON
Vol. 16 No. 2 April 2008
FLIGHT CONTROL SYSTEMS
F
light of modern manned aircraft and Unmanned Air Vehicles (UAVs) entails
design and development of sophisticated avionics systems, the most critical of
them being the Flight Control Systems (FCS). In order to fly a manned aircraft or an
UAV safely and reliably through out their flight envelope (speed and altitude
envelope) and for execution of their missions, it is imperative that their FCS is highly
reliable and fast responding to the pilot commands.
The FCS translates pilot's or controller's manoeuver-specific commands into
electric signals that actuate control surfaces of the aircraft and enable the aircraft to
achieve the commanded motion or trajectory. The attitude of the aircraft and its
velocities and accelerations are sensed by inertial motion sensors, air data
transducers and accelerometers. The sensed values are transduced into electric
signals and depending upon the differences between the sensed and commanded
values appropriate electric signals are transmitted to servo-actuators of the
aircraft's control-surfaces. The relationships of aircraft motion and control-surface
(elevator, ailerons and rudder) positions are called 'Flight Control Laws'. These
laws are incorporated in the Flight Control Computer, which may be either an
analog computer or a digital computer. All these elements together constitute the
FCS of any aircraft.
DRDO has made significant advances in the field of FCS for high-speed
combat aircraft and UAVs. DRDO, has been spearheading the indigenous FCS
development efforts in the country and has successfully developed the state-of-theart FCS for India's indigenous LCA Tejas, UAV Nishant, re-usable aerial target
system Lakshya, and controlled aerial delivery parafoil system.
TECHNOLOGY
From the Desk of Guest Editor
DRDO has spearheaded Unmanned Aerial Vehicles (UAV)
technologies in India with successful design, development and flight testing of
Ulka—an air launched drone, Sparrow—mini remotely piloted vehicle,
Kapothaka and Nishant—tactical UAVs and Lakshya—an aerial target, which
have been productionised for all the users. In accordance with the UAV
roadmap to meet the requirements of services, DRDO has embarked on the
design of Rustom—a medium altitude long endurance UAV.
DRDO has built significant competence in the core area of flight control
systems for UAVs through systematic and disciplined approaches. It has
successfully test flown Tejas and flown UAVs like the Nishant, Lakshya and controlled aerial
delivery parafoil system through a careful design and development process, iterative process of
control law design using various high-fidelity simulation models, dedicated system engineering
activity, conservative and safety conscious hardware designs, structured software development
coupled with rigorous and uncompromising test procedures. This issue of Technology Focus gives
the overview of the flight control systems developed by DRDO for manned and unmanned aerial
vehicles.
(P.S. Krishnan)
Outstanding Scientist and Director
ADE, Bangalore
Flight Control Systems for UAVs
Nishant Surveillance System
Nishant surveillance UAV is a low speed, all composite material air vehicle designed for battlefield
surveillance and reconnaissance. The target acquisition and tracking by Nishant is performed by electro-optic
payloads mounted on a stabilised steerable platform. A sophisticated image processing system is used for
analysing the video images received from the onboard system. A Ground Control Station (GCS) provides
facility to the Controller for planning, validation and execution of the UAV's missions. An integrated avionics
package (IAP) comprising flight control mission and navigation computer, air data transducers, and command
encoder-decoder manages the flight control, navigation and mission functions on the UAV.
Nishant has been designed for following flight modes:
Automated launch phase
Manual flying
Semi-autonomous flight
Pitch hold, roll hold, heading hold and altitude hold, track hold
Fully autonomous mode with waypoint navigation (WPN)
Air data dead reckoning navigation with GPS and ground tracker updates
Link loss mode
Capability for in-flight mission plan change
Get-U-Home mode
Autonomous programmed flight modes
2
– Circle program
– Racecourse program across and along the leg
– Figure-of-Eight program across and along the leg
Some of the major contributions on Nishant FCS are
development of conservative and safety conscious hardware
like compact IAP with state-of-the-art embedded processors
like Zilog8002/Motorola Power PC,
electromechanical
actuators, advanced rate gyro packages, DoD-STD-2167Abased onboard flight software, and a high fidelity hardware-inloop simulation (HILS) facility matching with the diminishing
cost and time frames of UAVs.
Lakshya Reusable Aerial Target System
Lakshya reusable aerial target system is a cost-effective
high-subsonic aircraft powered by a gas turbine engine and is
launched either from ground or a ship. It carries two tow
targets which are deployed in flight by a tow cable of 1500
meters length. These tow targets carry out a realistic
simulation of enemy aircraft threat, and are used by artillery
crews or combat pilots for training in air-to-air and surface-toair weapon system engagement. The two tow targets have IR
or RF signature augmentation systems to simulate the aerial
threat and are fitted with acoustic or Doppler miss distance
indication scoring systems that indicate to the artillery crews
whether the weapon has scored a hit or a miss on the target. At the end of the mission the aircraft is recovered
on land or sea by a two-stage para recovery system.
The Lakshya FCS has achieved the following in flight:
Autonomous waypoint navigation
Low level flight at 50 m
Altitude control
High `g' turns
Flight Control Computer
Flight control computer (FCC) is the heart of FCS. It is based on processor with fault tolerant features
embedded with the onboard flight program (OFP), performing mission navigation, auto-pilot and failure
management functions and interfaced with sensors, actuators and tele-command system. Design has the
scope to upgrade the system such that the rapidly changing technology in the processor can be absorbed.
The development efforts have been made in this field from fixed-point arithmetic computer to floating point
micro-processor leveraging the rapidly changing technology.
Integrated Avionics Package
IAP is designed and developed to execute various flight tasks like flight controls, mission, navigation and
failure management.
Salient Features
Flight control CPU, 16-bit fixed point
3
TECHNOLOGY
Integrated Avionics
Package
Elevator Actuator
Vertical Gyro
Aileron
Yaw Rate Gyro
Rudder
Heading Sensor
Servo
GPS Antennae
• 16 bit fixed point processor Z8002
Amplifier
• Analog Backup Unit
Package
• Air Data Transducer
• Base band PCM Code for pilot command interface
controller
• GPS and Heading interface adapter based on m
Engine
Control
Elements of FCS
Programmable frame time
32 analog I/Ps and 8 analog O/Ps
16 digital inputs/outputs
Two RS232 interface
DPRAM interface for inter processor communication
o
o
Operating temperature: 20 C to 70 C
Hot standby analog backup functions catering for control of UAV roll, pitch and throttle with recovery
checks and incorporates destruct functions in case of flight control processor and link failures
Airborne encoder and decoder for tele-command interface
In-built IAS and altitude sensors and interfaces
Power PC-based FCC
The next generation FCC is built around the Motorola PowerPC, a new breed of automotive controller
based on PowerPC architecture. This has a powerful RISC engine operating at 40 MHz and includes
hardware-floating point unit with variety of on-chip capabilities. The built-in CAN controller has been utilised for
communication with other computers through the CAN transceivers. The system is debugged using
BDM/JTAG port. The onboard FPGA includes the hardware for autonomous handling of GPS and Heading
sensors interfaces saving processor time. FPGA provides the expansion/upgradation facility. This computer
and its variants are used in variety of flight control applications.
Salient Features
Handles 32 analog I/Ps
4
64 discrete I/Os
16 high precision analog outputs in addition to 9 PWM outputs
Internal flash of 448 kb
Internal SRAM of 26 kb
External NVRAM of 2 kb
External burst flash 2 MB
External SRAM 512 Kb
Watchdog timer for health monitoring
Serial protocols—SCI, SPI, RS232, CAN
RTOS support
Real-time fault logging with NVRAM
Actuation Systems
PFCC unit
Actuation systems are complex high technology items which drive the control surfaces based on the
electrical signals received from FCCs. Actuator for UAVs are of electromechanical type consisting of a motor
driven by gears; sensors like LVDT, RVDT, and synchro for feedback; and a servo electronics for closing the
loop. Stringent performance and space constraints make them unique products posing a real challenge to
designers in developing such compact and intelligent hardware. DRDO has indigenously developed
electromechanical (EM) actuators for UAVs in torque range of 1-10 kgf-m with samarium-cobalt motor
(brushed), rotary/linear pot and gears fabricated from maraging steel. The servo amplifiers are linear/PWM
type. Present EM actuators under development are of brushless motor with electronic commutation, digital
servo loops with redundant/fault tolerant designs to meet the high integrity, reliability and performance at
reasonably low cost. The EM actuators with state-of-the-art features like DSP-based digital controllers, single
LRU-based controllers for controlling multiple actuators are conceived for advanced UAVs.
Salient Features
BLDC motor
LVDT sensor for position loop feedback
Compact size with necessary linkages and
neutral locking
Low threshold (0.1 per cent FS)
High accuracy (0.02 mm)
High bandwidth (up to 12 Hz at 10 per cent
amplitude)
Lakshya
Torque : 3.5 kgf-m (cont.); 6.5 kgf-m
(stall)
o
Rate
: 200 /C
o
Travel : + 20
Nishant
Torque
(stall)
Rate
Travel
BW
: 1 kgf-m (cont.); 2 kgf-m
o
: 100 /C
o
: + 20
o
: 2.5 @ 6.4 Hz
Rustom
Torque
Rate
Travel
BW
20 N-m (cont.); 90 N-m (stall)
o
160 /C
o
+ 20
o
2.5 @ 6.4 Hz (loaded)
o
2.5 @ 10 Hz (unloaded)
Supply : 28 + 4V
DSP-based digital controller
Advanced power electronics
BIT facility
:
:
:
:
Sensors
Sensors provide the state feedback to the guidance and control systems for achieving the autonomous
flight of UAVs. The sensor suite developed for UAVs include yaw rate gyro, vertical position gyro and heading
sensor for active feedback to auto pilot; static and total pressure transducers, radar altimeter and GPS for
navigation. Air data sensors provide the static and total pressure data and the heading sensor provide the
direction inputs for air data dead reckoning (ADDR) navigation. Customized GPS is used as mission critical
sensor to aid ADDR navigation. The sensors are mainly driven by the cost and availability and most of them
5
TECHNOLOGY
are COTS based. The rate and vertical position gyro
provide the vital inputs for the control of UAV for
damping augmentation and attitude tracking. Micro
electromechanical sensors (MEMS) are replacing the
conventional electromechanical sensors saving cost,
weight and volume for the UAVs under development.
Software
Onboard flight program (OFP) is the brain of entire
FCS integrating all the subsystems. OFP supervises
the functionality of sensors, actuators and FCC. The
OFP primarily executes the navigation, guidance and
control (NGC) algorithms, mission logics, failure
detection functions in addition to initialization of I/O
drivers, data acquisition from sensors and driving
actuators.
A strict development methodology based on DoD-STD-2167A/DO 178B with standard software
engineering practices are followed throughout the software development process for UAVs to ensure high
degree of reliability and traceability.
At each milestone of the different phases of software development, baselines are identified and placed
under configuration control. Further updates follow a strict change control process. An independent software
quality assurance team supervises/ensures the quality aspects of the software.
Salient Features
Tailored version of DoD-STD-2167A/DO 178B
S/W Development through case tools for each phase
– SRS/IRS
– DOORs analyst
– Design
– Rhapsody
– Code
– Green Hills Ada/GNAT Pro Ada compiler
– Test
– Ada test
– Configuration
– Synergy
Separate teams for SRS/IRS generation, design and coding, CSU/CSC test and SQA
Language for S/W development—Assembly/Ada95
Development platform: Sun Server with thin clients/PC servers
RTOS—VxWorks
Testing and Evaluation of FCS
Hardware-in-loop Simulation Facility for UAVS
Hardware-in-loop-simulation (HILS) is a very important test facility in which the simulated aircraft
dynamics activates the actual flight control electronics, the associated sensors and the control surface
actuators in an interactive manner with high degree of fidelity. It is an essential and major tool in design
evaluation and analysis of FCS, optimisation of flight control laws, hardware-software integration, and
verification and validation of integrated software.
6
Functions of HILS
Evaluation of integrated flight
control hardware and software
Va l i d a t i o n o f n a v i g a t i o n ,
guidance, control laws, mission
logics and flight mode functions
UAV controller training, mission
plan generation and evaluation
Capability to interface with
actuators in UAV and state
sensors installed in the motion
simulator
Capability to simulate in-flight
FCS emergency logics
(redundant management
functions, get to home functions,
etc.)
A HILIS architecture
Coupling studies between flight control and payload stabilisation loops
Advanced HILS (AHILIS) facility meets the growing complex requirements of FCS with high degree of
fault tolerance. AHILS has the capability to test all the failure in order to validate the robustness of the FCS
design. AHILS has the following elements:
Simulation node cluster (SNC): Constitute flight dynamic simulator (FDS) and other simulation modules
AHILS control station (ACS): Comprises UAV engineering test station, UAV FCS engineering console,
data recording archiving, etc.
Signal conditioning and switching subsystem (SCSS)
Specific connection panel for FCC (FCC–CP)
Three axis motion simulator (TAMS)
Controlled Aerial Delivery System
Controlled aerial delivery system (CADS) is an aerial delivery system that delivers a payload of 500kg
autonomously to a designated target within a 100m circular error probability (CEP) using ram air parachute
(RAP). RAP can be easily maneuvered, as it can glide and turn. FCS of CADS automatically steers RAP to
designated point by operating its two lanyards as a function of the cross-track error in the flight path and
heading errors etc. Upon completion of the descent, a flare maneuver is performed for accomplishing soft
landing.
Salient Features
Manual and Autonomous modes of operation
Low cost sensors based navigation
Energy Management Maneuver based guidance for altitude
control
Fault tolerant features against temporary tele-command and
GPS link losses
Manual override capability for safe recovery
Maximum range of 20 km when released from 10 km altitude
7
TECHNOLOGY
CADS FCS consists Motorola PowerPC based onboard flight control processor with Operational Flight
Program developed in Ada 95 language; a pair of electromechanical actuators whose electronics is packaged
in a single LRU; GPS and pressure transducer for navigation in addition to radio modem for telemetry to
Ground Control Station.
FCS for manned Combat Aircraft—Tejas
LCA Tejas has emerged as the lightest multirole combat aircraft in its class. Tejas is a supersonic
aircraft, with statically unstable tailless compound
delta wing-planform.
DRDO has designed and developed a truly
digital, full authority, quadruplex redundant flight
control system without electrical/mechanical
backup for Tejas to enable extreme manoeuverability and superior agility. The system
employs an advanced air data system, the heart of
any fly-by-wire aircraft. The system's robust preflight and in-flight BIT (built-in-test) capabilities
enable a high level of fault detection, isolation and
tolerance. The system allows the aircraft for 'carefree-manoeuvering' through real-time structural and
departure control. The system monitors continuously its health status, stores the data, and annunciates the
critical data to the pilot through the cockpit displays and caution warning lamps.
The reliability requirements of the system require survival of two electrical failures or one electrical failure
followed by one hydraulic failure or vice versa. The mean time between failures for the FCS should not be less
than 400 flight hours and for the digital flight control computer (DFCC) not less than 1000 flight hours. The
probability of loss of control must be less than one in ten million hours.
The reliability of the system has been ensured after careful analysis through (i) reliability logic diagram
generation, (ii) estimation of failure rates for components, functional blocks, subsystems, channel and
system, and (iii) failure modes, effects and criticality analysis and fault tree analysis.
The design, development, integration, and testing of the DFCS software has been done as per DoD
standards. The DFCS basic operational cycle comprises:
Reception of pilot's inputs such as control stick, rudder pedal, trim inputs, etc. by the DFCC
Processing of these inputs and other aircraft sensor (air data and inertial) inputs
Computation of control surface commands based on control law
Driving the control surface actuators and hence controlling the aircraft
The sophistication of the system lies here as these operations have to be independently done by each
channel of the quadruplex system, come to an agreement on system input received as well as the command
output to be generated. This is executed through complex redundancy management scheme and crosschannel data linking between the DFCS channels, synchronised in hard real time.
Tejas FCS employs the state-of-the-art sensors and actuators. The advanced technologies which give
these sensors a superior performance and fault tolerance make system integration a challenge. DRDO has
8
successfully integrated advanced class of sensors and actuators in its FCS and proven it through 820 fault
free flights. Tejas DFCS architecture has been extended to its variants and its naval version. The DFCC
acceptance tests, hardware-software test integration, software validation tests, etc. for DFCS of all the
variants are carried out in the sophisticated test rig called, Engineering Test Station, which is again an
indigenous development of DRDO.
Digital Flight Control Computer
DRDO has developed the quadruplex digital flight control computer (DFCC) for the Tejas FCS. The DFCC
is an Intel 80960 µC-based 32-bit quad redundant computer having a throughput of 2 MIPS (1750 digital
avionics instructions per second equivalent). The cross-channel data links transfer data across the four
channels at 2 MBPS. Over 512 parameters are exchanged for redundancy management.
The I/O interface consists of 256 channels of 12-bit ADCs (analog to digital converter) and 32 channels of
12-bit DACs (digital to analog) with full scale accuracies of not less than 99.81 per cent and redundant high
performance RS422 and MIL 1553B links to the rest of aircraft avionics and instrumentation. The DFCC has a
fault detection capability of more than 95 per cent through BIT and has a proven reliability of 5235 hours MTBF.
DFCS Software
DRDO has designed and developed the OFP for the Tejas FCS. This OFP executes identically in all
DFCS channels synchronously in hard real time. Being safety critical, the software is developed as per DoD
Standard adhering to strict quality standards of design, coding and testing. Ada is used as HLL (high level
language) as per MIL-STD-1815A. The software incorporates object-based software modelling and design
principles organised in 28 packages. The foreground execution time of OFP is 10.5 ms peak. DRDO has
developed process methodologies to ensure 100 per cent CSU/CSC testing capability as this software is
safety critical.
The major OFP computations consists of various logic, arithmetic, I/O intensive operations such as
redundancy management of sensors, actuators; optimized control flow design to meet best system
performance (80, 40, 20, 10 Hz); BIT and critical failures annunciation to pilot; and control law computations.
Salient Features
Inhibition of failed signals from participation in control commands
Switching to fixed gain control laws on second air data failure
Ensuring symmetry by disconnection of Elevon actuators on third failure
Elements of Tejas DFCS
Tejas DFCS architecture
9
TECHNOLOGY
Full retraction of LES (leading edge slats) on second
failure
Recovery from re-settable faults on pilot reset
Masking nuisance/transient hardware faults
In flight BIT and pre-flight BIT
‘Inline monitoring' to isolate third failure
Incorporating boundary limiting and reconfigurable
control laws.
Tejas DFCC and its SRUS
Air Data Computer
DRDO has designed and developed advanced air data computer (ADC), which in quad configuration will
collectively receive and process the raw signals from air data sensors thereby unloading this computational
load from DFCC in future limited series production (LSP) variants of LCA.
Each ADC transmits the data received from the air data sensors (probes and vanes) to other three ADCs
by the built-in inter ADC communication interface for effective redundancy management of the air data
parameters. The ADCs CSCI performs the redundancy management of air data parameters and sends
corrected, selected air data parameters as outputs signals on RS-422 serial data link to the digital flight control
computer (DFCC). Each ADC also accepts data on RS-422 serial link @19.2 K from the DFCC. The Inter ADC
communication link is implemented in FPGA.
Salient Features
32-bit INTEL 80960MC based CPU with a high-end re-programmable XLINX FPGA hosting the logic built
on a Integrated motherboard and flex assembly
IEEE 1149.1 compatible scan chain
Inter ADC Communication Controller for RM, Wrap for DI/dos, IACL transmitter/ receivers
BIT with greater than 95 per cent coverage
MTBF > 1000 hours
DRDO is also currently developing the LEVCON air data computer (LADC) which is an advanced version
of ADC to enable the leading edge vortex control (LEVCON) surface control and auto-throttle function along
with present air data computation for the naval variants of LCA.
Air Data Computer Software
The ADC software computation consist of air data computations on static and total pressures, angle of
attack, angle of sideslip, and total air temperature. The software also computes derived parameters such as
outside air temperature, calibrated air speed, Mach number, etc.
The software also features failure annunciation to pilot and BIT
capability.
FCS Test Unit
The flight control system test unit (FTU) is a 16-Bit MCUbased embedded real-time unit installed in the cockpit of LCA
interfaced with DFCC. The FTU is a signal synthesiser capable of
generating a variety of analog or digital signal (communicated
over RS-422 link), used during flight testing (flutter test and
parameter identification test).
10
FCU
Waveforms such as linear sine sweep, logarithmic sine sweep, random signal, half-sine pulse, 3-2-1-1
pulse train, etc. are synthesised using algorithms with any desired characteristics, i.e., amplitude,
frequency/period, off-time, numbers of repeats, etc. The FTU provides control switches and indicators on the
front panel for quick selection of test point initiate and abort the signal synthesis and discrete signals to
indicate the event/status of unit. It serves as means to insert an external EPROM with signal characteristics of
100 test points.
Rear Cockpit FTU
The rear cockpit FTU (RCFTU) is designed and developed as part of
DFCS of LCA trainer and is installed in the rear cockpit. It is a slave to the
FTU installed in the front cockpit. It is provided with control switch and
indicators on the front panel to display the status of FTU and a means to
abort the signal synthesis that is in progress at FTU.
RCFTU
Flight Control Panel
The flight control panel (FCP) is installed in the cockpit of LCA and is
interfaced with DFCC. The MTBF is around 9000 hours. FCP provides
the following to the pilot: yaw trim control in normal and emergency
modes; pitch and roll trim control in emergency mode; normal to
emergency mode change over for trim controls, normal to standby gain
change over for FCS; and initiate BIT of FCS and visually annunciate BIT
result.
Digital Interface Unit for LCA Trainer
DRDO has also designed and developed a digital interface unit (DIU)
for the trainer variant of the LCA to interface the control stick, rudder
pedal and discrete inputs from the front and rear cockpit to the DFCC.
FCP
Tejas Actuators
The actuators of Tejas FCS comprise Elevon, rudder, leading edge slats, and airbrake actuators. The
four Elevon and one rudder actuators are quad electrical redundant, and dual hydraulic redundant. The
Elevon and rudder electro-hydraulic servo actuators incorporate the state-of-the-art 'direct-drive-valve'
technology in their hydraulic control modules. The six leading edge slat actuators incorporate 'flapper nozzle
type' electro-hydraulic servo valves in their hydraulic control modules. Both, the slat and airbrake actuators,
are dual electric redundant single hydraulic. These actuators are powered and servo controlled by the analog
loop closure electronics in DFCC, with position monitor by linear voltage differential transformers (LVDT). All
the servo actuators functions with 280 bar hydraulic pressure and have a minimum bandwidth of 9 Hz. The
redundancy management of these actuators is done by the OFP software for the failure modes detected by
DFCC and by hydraulic components such as solenoids and bypass valves in the actuators in the case of
hydraulic power losses.
Tejas Sensors
The inertial sensors of the Tejas DFCS are the quad redundant rate sensor assembly (RSA) package
comprising 12 rate gyros for sensing pitch, roll, Yaw rates, and the quad redundant acceleration sensor
assembly (ASA) package comprising eight accelerometers for sensing lateral and normal acceleration. The
rate sensor used is rate integrating type with self BIT capability. The acceleration sensor is Force balanced
pendulous mass type with self BIT capability. Each channel of these inertial sensors are electrically separated
and mechanically segregated. Excitation voltage of RSA is 12 VAC, two phase, quasi square wave with a
11
RNI No. 55787/93
frequency of 400 Hz with maximum rated output of 6 V. Excitation voltage of ASA is +15 V and maximum rated input is
13 g and 4.5 g for normal and lateral accelerations, respectively.
There are two angle of attack (AOA) sensors (vane type), one total air temperature probe, two-side air data probes
and one nose air data probe for sensing and providing air data parameters to the air data computer (ADC) for
computations. DRDO has designed and developed the indigenous de-icing current sensor unit (DCSU) to accommodate
the requirements of the improved air data system for the future variants of LCA.
Ground Test Rig Facilities
Engineering Test Station and Mini-Bird
This is a multiprocessor-based realtime, automatic/manual
test station used for the
functional verification of
FCS. Engineering test
station (ETS) provides
capability to simulate,
stimulate, monitor and
generate failure for all the
inputs/outputs of the
DFCC. The ETS is used
Engineering test station
Mini-bird test stand
for acceptance testing and
real-time hardware/software integration of the DFCC, system integration, and testing of the LCA-FCS. It can replace
some or all simulated sensors and actuators with real hardware. Also, the ETS interfaces with the mini-bird and iron-bird
test facilities to monitor the DFCC performance during closed-loop testing, pilot-in-the-loop testing, interface calibration,
end-to-end dynamic testing and FCS verification and validation.
Technology Focus highlights the technological developments in DRDO, and also covers the products, processes, and technologies.
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Coordinator
Dr AL Moorthy, Director, DESIDOC, Metcalfe House, Delhi
Members
Dr BR Gandhe, Director of Armaments, DRDO Bhavan, New Delhi
Dr Sudarshan Kumar, Director of Materials, DRDO Bhavan, New Delhi
Shri CU Hari, Director of Aeronautics, DRDO Bhavan, New Delhi
Dr RC Sawhney, Director of Life Sciences, DRDO Bhavan, New Delhi
Shri Ranjit Elias, SO to SA to RM, DRDO Bhavan, New Delhi
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Editor-in-Chief
AL Moorthy
Assoc. Editor-in-Chief
Ashok Kumar
Editors
B Nityanand
Manoj Kumar
Printing
SK Tyagi
SK Gupta
Distribution
MG Sharma
RP Singh
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nwjHkkÔ: 011-23902475; 23902465
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nzks.kk&esy: technologyfocus@desidoc.deldom
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baVjusV: http//www.drdo.org/pub/index.shtml
Readers of Technology Focus are invited to send their
communications to the Editors, Technology Focus
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Internet: http//www.drdo.org/pub/index.shtml
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