SPECIFICATION OF THE INVENTION

1. Title of the invention
A novel system and method for providing guidance to the pilot for releasing a bomb during a turn.

2. Field of Invention
The present invention relates to weapon aiming from aerial vehicles. In particular, it relates to a methodology of computing and displaying the impact point on head up display system for a bomb released from an aerial vehicle during a turn.

3. Prior art and Draw backs of prior art
Military aircraft are equipped with variety of weapons of which some are used for air to air attacks and some for air to ground attacks. For air to ground weapons again there comes the classification based on guided or unguided weapons. Using unguided weapons, like drop bombs weapon aiming and attack for ground target is performed visually by seeing the target using head up display system. Prior to this invention, weapon aiming for the ground target using unguided bombs were performed only during straight flight of the aircraft. This limits the weapon aiming and attack capability of the aircraft for its entire envelope of operation.

4. Aim of Invention
The main objective of this invention is to enhance the weapon aiming and attack capability of the aircraft. This is achieved by computing weapon aiming cues for displaying the bomb fall line for targeting a ground object during the turning phase of the aircraft.

5. Summary of the Invention
This invention presents a weapon aiming system employing a novel method for computing the weapon aiming cues for the bomb fall line during the turning phase of the aircraft. The Weapon Aiming System (WAS), 102 interacts with Inertial Navigation System (INS), 101 to receive the aircraft's present attitude angles. It also interacts with Ballistic Computer Module (BCM), 100 to receive forward throw of the selected bomb, aircraft ground speed and the coordinates of flight path marker. The information regarding starting of turn is provided by the Upfront Control Panel (UFCP), 104 to the Weapon Aiming System (WAS).Using all these information Weapon Aiming System computes the targeting cues required for displaying the bomb fall line on Head Up Display system (HUD), 105.The computed parameters are then passed to Mission Computer (MC), 103 which in turn places the desired bomb fall line on Head Up Display System (HUD), 105.

6. Brief Description of the Drawings
Figure 1 is a Schematic of different systems involved in computing and displaying the bomb fall line during a turn.

Figure 2 is a Flow Chart depicting the formal steps involved for the computation of bomb fall line during aircraft turn.

7. Detailed Description of the Invention
The Weapon Aiming System interacts with different sensors and module for its position computation of bomb fall line during the turning phase of the aircraft. The Fig 1 explains the different steps involved for the computation of position of the bomb fall line to be displayed on Head up Display System.

In the starting, at step 200 the system receives forward throw i.e Sx, Sy and Sz, Aircraft ground velocity in x direction (Vgx) and the Flight Path Marker Coordinates(XFPM,YFPM) and the offset distance(Zx,Zy,Zz) of the weapon from HUD axis from the Ballistic Computer module,201.

At step 203, the system interacts with Inertial navigation System at 202, and receives aircraft attitude information i.e Roll (0), Pitch (e) and Yaw (cp).

At step 204,forward throw(Sx.Sy) and Sz in ground axis system is transformed to aircraft axis system as below-

The direction cosine matrix for Transforming Ground axis system to aircraft axis system are formed as -
L10 = cosG,
L20 = 0,
L30 = - sin 0,
M10 = sin e sin ,
M20 = cos ,
M30 = cos 6 sin,
N10 = sin 9 cosf
N20 = - sin 4,
N30 = cos 0 cos,
Where 0=Pitch angle and =Roll Angle.
Using the above direction cosines Sx.Sy and Sz are converted into Si,Sj and Sk of body axis as-
Sj=SxMw + SyM20 + SZM30
Sk=SxN10 + SyN20 + SZN3Q + Zz

At step 205, the coordinates of the impact point represented by bomb fall line is computed in Head Up Display axis system as below-
H -Sk dec =TT

At step 206, a check is performed whether the computed (acc, dcc) is out of Head up Display Field of View or Not.

At Step 207, if the computed {acc,dcc) is not out of Head up Display Field of View.a normal Bomb fall line is drawn on HUD using the above coordinates of the impact point(acc,dcc).

At step 208,it is checked that whether a key press * is received from Up front Control Panel(210) or not.

At step 209,if no key press * is pressed, then a dashed bomb fall line without showing the impact point is displayed on Head Up Display System.

At Step 211, radius of the turn is computed using the roll of the system as below-V 2
turn , gxtan0

At Step 212, arc length of the turn is computed as below-

Elevation distance between Flight path Marker position and impact point of the bomb fall line is computed first as below
ElevDiff = dcc - YFPM
Arcturn = sin
turn

At step 213, the above computed angle is divided in 10 parts and the continuous straight bomb fall line is converted into discrete curved path as below-
ATCturn
Angleby9 =

Loop it for 10 times using the count as loop counter variable-Set count=0 Anglepoint = count x Angleby 9
Assign the array az count = rturn - rturn x cos Anglepoint

Assign the array az bflvoint count = count x count x £!£_££IfZL_ x 10OO x

Assign the array az_bfljpoint count = acc + az_bfljpoint count Assign the array dep_bfljpoint count = dec

Increment the count by 1

At step 214,the collected coordinates of the bomb fall line in the arrays az_bfl_point, dep_bfl_point are sent to head up display system for drawing the bomb fall line in a turn.

CLAIMS
We Claim

1. A Weapon Aiming System employing method for generating bomb fall line during the turning phase of aircraft for accomplishing its combat mission.

2. The Method of Claim 1 is characterized by the interaction of the Weapon Aiming System with the Inertial Navigation System, Ballistic computer Module, Up Front Control Panel and Head up Display System.

3. The Method of Claim 1 involves computation of the position of bomb fall line using attitude data from inertial navigation system and forward throw from Ballistic Computer Module during the turning of aircraft.

4. The Method of Claim 1 involves interaction with Up Front Control Panel to receive information for the starting of turn.

5. The Method of Claim 1 involves display of bomb fall line on Head up Display system during the turning of aircraft.