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Gerard Leng, MDTS, NUS
MDTS 5705 : GuidanceLecture 1 : Guidance System Requirements
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Course Admin
Instructor : Gerard Leng
Office : E2 -02 - 37
Contact : phone 6 874 6548fax 6 779 1459
e-mail [email protected]
Consultation : Mon-Fri 12-2pm (happy hour)
Course Website : dynlab.mpe.nus.edu.sg/mpelsb
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Course Outline
Topics
1 : Guidance System Requirements
2 : Line-of-sight Guidance
3 : Homing Guidance
4 : INS/GPS Guidance
Course Organisation
4 lectures/tutorial
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Course Objectives & Requirements
1. Understand theoreticalguidance concepts
2. Relate these concepts topractical weapon systems
Required Background
Basic engineering or science degree
( calculus, differential equations, particle dynamics )
Some programming experience ( eg : Matlab )
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Text
P. Garnell & D.J. East, Guided Weapon Control Systems, Pergamon
Press, 1977
A.S. Locke, Guidance,Principles of Guided Missile Design, van
Nostrand, 1955
E. Fleeman, Tactical Missile Design, AIAA, 2006
P. Zarchan, Tactical and Strategic Missile Guidance , AIAA Progress inAstronautics & Aeronautics, v239, (6th edition), 2012
Recommended references
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Grading Policy
Proposed grading - Plan A
Project 40%
Final Exam 60%
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1.0 What is a guided weapon ?
Guided Weapon = Sensors (Eyes & Ears)
+ Guidance Logic (Brain)
+ Control & Propulsion (Muscles)
+ Warhead
In other words .
A guided weapon is a weapon system that can
correct its course to hit a target
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Example : The earliest guided bomb
WWII German Fritz X
Specifications
Weight 1300 kg, 270 kg AP warhead
Wing span 1.6 m Guidance joy stick, radio link
Range 5.6 km
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Example : The earliest guided missile
WWII German HS 293
Specifications
Launch weight 1045kg, 295 kg HE warhead
Wing span 3.10m
Guidance joy stick, radio/wire link
Propulsion rocket
Range 18 km
http://localhost/var/www/apps/conversion/movies/ASM/FritzX.mpg8/10/2019 GW 1n v2
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Question : What can we observe & conclude from
these early guided weapons ?
A guided weapon doesnt have to be really high-tech or even
autonomous
So can we build one with commercial-off-the-shelf (COTS)
components ?
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1. 1 Mission profile of guided weapons
1.1.0 Guided weapons with different missions Anti Tank Guided Missile ATGM
Air to Ground Missile AGM
Anti-Ship Missile ASM Surface to Air Missile SAM
Air Interdiction, Air-to-Air Missile AIM, AAM
Anti-Missile Missile AMM
Unmanned Combat Air Vehicles UCAV
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1.1.1 Anti-Tank Missile Mission Profile
Question :Is a direct head on impact the most effective way for an ATGM
to destroy a tank ?
1. missile aligned with tank 2. head -on impact on the front hull
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What is the best way to destroy a tank ?
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Russian MBT T-72
Basic protection : 520mm - 590mm turret armour against HEAT
Main armament : 125-mm gun with range of 2000 m
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ATGM flight trajectories
2. Elevated - Hellfire
1. Direct - Milan
3. Arched - Javelin
Whats this ?
http://localhost/var/www/apps/conversion/movies/ATGM/ATGM%20trajectory2.mpghttp://localhost/var/www/apps/conversion/movies/ATGM/ATGM%20trajectory1.mpghttp://localhost/var/www/apps/conversion/movies/ATGM/ATGM%20trajectory3.mpg8/10/2019 GW 1n v2
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1.1.2 Anti-tank missile guidance requirements
2. Attack armoured targets at the weakest point (top armour)
1. Additional protection eg : ERA (explosive reactive armour)
3. Guidance design implications :
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1.2 What is the best way to destroy a ship ?
1.2.0 Warships can detect and defend against in-coming missiles
A : detection & launch
B : align with intercept plane
C : intercept course
D : target neutralised
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1.2.1 Anti Ship Missile Mission Profile
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1.2.2 Anti-ship missile guidance requirements
More complicated guidance design for different phases of mission
launch : dive/climb
mid-course : altitude hold
tactical maneuvers
terminal : pop-up
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1.3 How to destroy an in-coming missile ?
1.3.0 Problems
Target can be as fast as your missile
Target may approach from any direction
Target can perform evasive maneuvers
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1.3.1 Anti-Missile Missile Mission Profile
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1.3.2 AMM guidance requirements
Vertical launch to optimal altitude
Tip-over to correct plane for interception
Mid course guidance to close with target.
Terminal guidance to counter evasive maneuvers
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1.4 What are the guidance requirements for a UCAV
or a cruise missile ?
X45 X47
Hint : What kind of targets are suitable for UCAV or cruise missiles ?
1 4 1 UCAV/C i Mi il Mi i P fil
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1.4.1 UCAV/Cruise Missile Mission Profile
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1.4.2 Cruise missile, UCAV guidance requirements
1. Long range, low-level terrain hugging flight
2. Best used against large stationary targets
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1.5 The First Lesson of Guidance System Design
The design of the guidance system must suit the
mission profile and must function within the
limits of available sensors and controls
To paraphrase Sun Tzes Art of War
Know your guided weapon, know your target.
In a 100 firings, you get a 100 hits (or close)
i j A l i
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1.6 Basic Trajectory Analysis
q
g
R
V
a
OI
J
P
(1) Position of P
X = R cosq
Y = R sinq
1.6.0 Kinematics
(2) Velocity of P
X = V cosg
Y = V sing
X
Y
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1.6.1 Turn rate and latax
1. Differentiate eqns (1)
X = cosq -sinq R
Y sinq cosq Rq
2. Substitute eqns (2)
Vcosg = cosq -sinq R
Vsing sinq cosq Rq
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Inverting
R = V cos(g -q )
R q = V sin(g -q )
3. Conclusions :
a) The velocity component parallel to OP affects the rate of change of
OP
b) The velocity component perpendicular to OP affects the rotation rateof OP
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4. From the diagram, the lateral acceleration a = a { -sin g, cos g }
Differentiate eqns (2),X = cosg -sing V
Y sing cosg V g
5. Noting that the LHS is the lateral acceleration a
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We obtain
V = 0
V g = a
6. Conclusion
The (applied) lateral acceleration (latax) changes the turn rate but not
the speed
E i G tti h i l f l f th th
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Exercise : Getting a physical feel for the math
A fighter aircraft flying at 180 m/s (Mach 0.6) executes a 9g turn.
What is the turn rate ?
Noting that V g = a
m V g = ma = 9 mg
Hence g =
=
=
=
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Exercise : Estimating performance Aster 30 AMM
Reported : Dec 1997 test firingof the Aster 30 AMM
Intercepted target from aboveat Mach 2.68
miss distance < 4 m
max load = 60 gs
Whats the turn rate ?
max turn rate =
=