gunnery

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" height=94 BGCOLOR="#000000" TEXT="#F7F7FF"> <div>  <A NAME="gunnery"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></div> <div> <TABLE BORDER="7" CELLPADDING="5" CELLSPACING="3" WIDTH="118" BORDERCOLORLIGHT="#FFFFFF" BORDERCOLORDARK="#A6CAF0" FRAME="BOX" RULES="ALL" ALIGN="BOTTOM" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 16 WIDTH="86"><div> <A HREF="id77_aa.htm" TARGET="_top" TITLE="AA Engagement"><U><B>AAE-PAGE</B></U></A></div> </tD> </tR> </TABLE></div> <div> </div> </td> </tr><tr> <td valign="top" height=386 BGCOLOR="#FFFFFF" TEXT="#080000"> <bR> <div> gunnery</div> <div> <IMG SRC="77b43e40.jpg" border=0 width="835" height="228" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> <B>GAU-4 20mm Vulcan</B></div> <div> <B>M61A1/M61A2 20mm Automatic Gun</B></div> <DIV ALIGN="LEFT"></DIV> <div> Specifications</div> <div> <B>Designation</B> M61A1, M61A2 </div> <div> <B>Type</B> Six-barrel, hydraulically operated 20mm Gatling gun </div> <div> <B>Contractor</B> General Dynamics Armament Systems </div> <div> <B>Rate of Fire</B> 6,000 rounds per minute </div> <div> <B>Effective Range</B> Several thousand yards </div> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <div> <IMG SRC="71618e70.jpg" border=0 width="536" height="231" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> <B><U>The description of the Funnel Site</U></B><B> about maximum and minimum ranges.... The M61 round was that pesky PGU-28 round I had asked you about earlier and you have stated max range of "Usually 6000 feet" at the base of the Funnel.</B></div> <bR> <div> <B><IMG SRC="7171c2c0.jpg" border=0 width="540" height="300" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <div> <B><U>Dispersion</U></B><FONT SIZE="3" COLOR="#000000" FACE="Arial" >. A target shooter will fire his rifle a number of times to establish a ‘group.’ The smaller the group, the more accurate the shooter is. A modern aircraft gun has a similar characteristic. Technicians will fire the gun at a target and then count the projectile impacts and measure their pattern from the center aim point. Typically, this calculation will be expressed as a percentage of rounds fired within a certain area, usually a circle with the aim point at its center, and is called the gun dispersion. A typical modern gun dispersion results in about 80% of the rounds being grouped in a five foot diameter circle at a range of 1000 feet.</FONT></div> <bR> <bR> <div> <B><IMG SRC="7182b220.jpg" border=0 width="555" height="290" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <div> <B><U>Dispersion.</U></B><FONT SIZE="3" COLOR="#000000" FACE="Arial" > A target shooter will fire his rifle a number of times to establish a ‘group.’ The smaller the group, the more accurate the shooter is. A modern aircraft gun has a similar characteristic. Technicians will fire the gun at a target and then count the projectile impacts and measure their pattern from the center aim point. Typically, this calculation will be expressed as a percentage of rounds fired within a certain area, usually a circle with the aim point at its center, and is called the gun dispersion. A typical modern gun dispersion results in about 80% of the rounds being grouped in a five foot diameter circle at a range of 1000 feet.</FONT></div> <bR> <bR> <bR> <bR> <bR> <div> <B><IMG SRC="71912910.jpg" border=0 width="530" height="401" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <div> <B><U>Aspect angle</U></B><FONT SIZE="3" COLOR="#000000" FACE="Arial" >. This term is a measurement of position. The heading of the attacker relative to the target is irrelevant. Aspect angle refers to the attacker and is measured using the target as the reference. This measurement originates at the target’s six o’clock. This is the zero aspect position. The twelve o’clock position off the target’s nose is the 180 degree aspect position. From the six o’clock position to the twelve o’clock, aspect angles are referred to as either ‘right’ or ‘left.’ This is in reference to what side of the target you as the attacker are looking at. If you are looking at the target from its 3 o’clock position, you have a 90 Right aspect. And if you are looking at the target from its 7:30 position, you have a 45 Left aspect. Remember, your heading is not included in this term. Aspect angle is only a way of defining your position relative to the target.</FONT></div> <div> Note: Aspect and angle off tend to be used in the same manner when we talk about gun attacks. This is a unique situation and occurs because we are usually thinking of the attacker being pointed at the target. When the attacker has his nose on the target, then his angle off and aspect are basically the same. In this discussion, I’ll use the term ‘angle off’ with this in mind.</div> <bR> <bR> <div> <B><IMG SRC="71a36060.jpg" border=0 width="566" height="262" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <div> <B><U>The Gun Line Concept</U></B></div> <div> If you were to look through the barrel of the gun out to infinity, you would be looking along the gun line. The gun line establishes the initial vector of the round as it leaves the barrel (also known as the line of departure, the LOD). The gun line is an important part of the process of matching up the gun sight to the gun in an aircraft. It is the basis upon which all other calculations are made. If an aircraft has multiple guns, therefore it has multiple gun lines.</div> <div> In our modern aircraft HUDs, the gun line is often represented by a small cross. This cross is ‘fixed’, meaning it doesn’t move. You can think of it as being similar to the sight on the end of a rifle. It is one way of visualizing where the gun is aimed.</div> <bR> <div> <IMG SRC="71b151a0.jpg" border=0 width="533" height="282" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> <B><U>The Sight Line Concept</U></B></div> <div> The sight line is similar to the gun line. It too is a line from the eye to infinity, but this time, we are talking about the pilot’s eye as seen from the cockpit. Since few guns are co-located in the cockpit, there is a difference in the physical location of the gun line and the sight line. The following figure illustrates this difference.</div> <bR> <div> <IMG SRC="71c21480.jpg" border=0 width="545" height="328" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> <B><U>Gravity Drop</U></B></div> <div> Once the round leaves the barrel, it becomes a falling object subject to the laws of gravity. A round will drop approximately 16 feet in its first second of flight. The next figure will give you an appreciation of this factor. In this figure, notice that the pipper in the reticle is below the gun cross. The aircraft is in wings level flight at one G. The pipper position represents the gravity drop of the round over the range that the sight is computing for. As you can see, gravity drop is not an insignificant value as TOF increases.</div> <bR> <bR> <div> <IMG SRC="71d31ed0.jpg" border=0 width="561" height="237" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> <B><U>Harmonization</U></B></div> <div> In discussing harmonization, we will use the concepts of gun line, sight line, and gravity drop. Harmonization is the process of lining up the gun line so that it intersects the sight line at some point in front of the aircraft. The TOF for the round to cover that distance will be computed and used to calculate a gravity drop value. That value will be added to the gun line. Then the gun(s) will be adjusted so that the resulting projectile path (including gravity drop) will intersect the sight line.</div> <div> In older fighters that had guns installed in the wings and nose, harmonization was much more of a factor to be considered. The basic idea is to adjust the guns so that all the gun lines converge at a predetermined distance. Why, you ask? Some might think it would be better to have the guns adjusted to spread out the gun lines...that way the pilot might have a better chance of hitting something. Now, there is a smidgen of logic to that idea, but only a smidgen. The better idea is to have the gun lines come together. That way the pilot has a highly concentrated area of fire that will deliver a killing blow to whatever it hits. Certainly, that area may be relatively small, but the issue is not the size of the projectile impact area. Instead, the issue is accuracy in aiming. We’ll get to that eventually. For now, we just want to establish the idea that harmonization is the process of converging gun lines so that they intersect the sight line at a predetermined distance.</div> <div> During WW2, harmonization was a hot topic among pilots. The debate raged back and forth over what range the guns should be harmonized at. Some liked a short range…short being in around 300 feet. Others wanted the range a bit further out…as much as 1000 feet. In many fighter units, the matter was left up to individual preference.</div> <bR> <bR> <div> <IMG SRC="71e1b090.jpg" border=0 width="539" height="265" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> <B><U>Projectile Density</U></B></div> <div> In simple terms, projectile density refers to how many bullets we can expect to have in a given amount of space at a particular point in front of our aircraft. We all immediately recognize that the denser the bullet pattern, the greater chance we have of hitting our target.</div> <div> We have all seen the WW1 movies of the Red Baron blasting away at his opponent. Rat-tat-tat-tat! One, maybe two small caliber machine guns. A moderate rate of fire for the time. But nothing like the modern guns of today’s fighters. Today, the common perception is that a fighter’s gun fire is like a red hot laser beam. Well, not quite!!</div> <div> Let’s try to interject a reality check to the matter of projectile density. What you want to take away from this part of the discussion is the understanding of how angle off and aspect angle affect your chances of hitting your target.</div> <div> We’ve all heard it before. "Man!! That Gatling spits out 100 rounds a second! Nothing can escape that kind of firepower." If only it were so. Too often, the typical person visualizes those 100 rounds all in the same spot. Not true. A little math will make this clear.</div> <div> Let’s fire a one second burst from our M61. 100 rounds, just for argument’s sake. Now let’s picture what the bullet stream looks like. For starters, it’s 3000 feet long…remember muzzle velocity. As the last round is coming out of the barrel, the first round is one half mile away! Spread those rounds out over that distance, and we end up with one round every 30 feet. Then we have to remember dispersion. The bullet stream is not a ‘frozen rope.’ Instead, it is a cone that is about 15-20 feet in diameter at 3000’.</div> <bR> <div> <IMG SRC="71f2c370.jpg" border=0 width="556" height="311" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> It is very important to visualize the bullet stream as three dimensional. In the next screenshot, the bullet stream is represented by a funnel display. The funnel extends below the gun line and appears to run through the target. Because of this fact, this may look like a valid aiming solution. But it is not. In fact the rounds that are at target range are in front of the target…this aiming solution has too much lead.</div> <div> <IMG SRC="7200e1d0.jpg" border=0 width="526" height="285" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> Figure 16 is a drawing of what the situation in Figure 15 would look like from a side view. This drawing when combined with the screenshot gives you the complete picture…a three dimensional visualization that makes the concept of the bullet stream much more meaningful.</div> <bR> <div> In seeing the bullet stream in this manner, significance of target angle off and apparent size becomes all too clear. The faster the target moves through the bullet stream, the less chance it has to be hit. If we as the shooter can do something to keep the target in the bullet stream longer, then we increase our chances of success. This is an aiming problem, and since this article is ultimately about aiming the gun, we’ll now move on to looking at that problem. We’ll call that problem ‘the lead angle solution.’</div> <bR> <div> <IMG SRC="72114190.jpg" border=0 width="532" height="281" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <div> There are two variables to solve for when we look at the lead angle problem. First, let’s identify that problem. We are in a gun platform that is moving. We are trying to hit a target that is also moving. We intend to shoot rounds at the target…this will take a certain amount of time (TOF) and this in turn will result in some gravity drop.</div> <div> The problem then is to fire our gun having taken into consideration two things…lead for target motion, and gravity drop. The next figure is a common illustration of the lead angle problem found in many sim manuals. Both the attacker and target are flying straight. The situation is similar to a skeet shooting problem. We’ll use this figure to discuss the problems in computing lead for target motion and gravity drop.</div> <bR> <div> <IMG SRC="722312a0.jpg" border=0 width="561" height="298" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <DIV ALIGN="LEFT"></DIV> <div> <B><U>The Common View Of The Lead Angle Problem</U></B></div> <div> <B>Computing the lead angle. </B>In a gun attack, the firing geometry can range from a pure tail chase to a head on set up. Clearly, the lead for target motion is greatest when the target angle off is 90 degrees and is essentially zero when the angle off is zero or 180 degrees. The gunsight computer must solve for this value, and the first question that always came to my mind was ‘how does the computer know where and what the target is doing?’ Believe me…when it comes to gunsight computations, that is the $64,000 question!!</div> <div> Our illustration shows a target that is not turning. Throw in a turning target, and the problem becomes very difficult to solve. In fact, it has only been in recent years that radar technology and computer improvements have been able to come close to an accurate answer. Prior to these new systems, gunsight computers used a number of assumptions about both the attacker’s and target’s flight behavior to arrive at a solution. As you might expect, life seldom matched these assumptions, and the resulting lead angle solutions were only approximate at best. Some of these assumptions included the following: the two aircraft were co-speed…the aircraft true air speed was a certain value…the range was fixed…the altitude was a constant…if the target was turning, it was turning at the same rate as the attacker. It was a lucky day for the attacking pilot when these assumptions matched the actual firing situation. More often than not, this was not the case, and the pilot had to fall back upon prior experience to make up for errors in his sight system.</div> <div> <B>Computing gravity drop.</B> We have already shown that the gravity drop value is a function of TOF. Many of the assumptions mentioned above also have a negative impact on the gravity drop calculation. Incorrect closure, range, and altitude values all result in errors…while the gravity drop part of the total lead angle is usually much smaller than the lead angle part, the value is still significant to the overall gunnery solution.</div> <div> <B>Putting it all together.</B> The next figure shows a hypothetical (and simplistic) view of the lead angle solution. In Part Two, we will go into each gunsight type in detail and explain how each type either does or does not replicate this view.</div> <bR> <bR> <bR> <bR> <div> <B>We should stop for a moment and make an important observation</B>.</div> <div>  It is much easier for a pilot to adjust the aim of a fixed sight if that sight is lined up with the roll axis of his aircraft. If this is the case, when the pilot makes flight control inputs to correct his aim, the aircraft will roll around the gunsight axis. If, however, the gunsight line is not aligned with the roll axis, then the pilot cannot use the sight as an aiming reference when making corrections. The reason for this is an aiming problem known as ‘pendulum effect’. Those of you that flew Sabre Ace will remember the difficulty in trying to use the gunsight as a maneuvering cue. This was because the roll axis of the F-86 in that simulation was not aligned with the gunsight. The next figures explain pendulum effect.</div> <div> <IMG SRC="723134d0.jpg" border=0 width="531" height="333" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> <IMG SRC="724133e0.jpg" border=0 width="531" height="318" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> <IMG SRC="72515400.jpg" border=0 width="533" height="320" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> The ‘ring’ part of the sight often had one or two circles. The diameter of these circles could be used to estimate target range. This is done by using a technique known as ‘stadiametric ranging.’ This concept is a central part of many past and current gunsight designs. In the discussions to come, we will look at reticles and funnels that use this principle in their operation, so a clear understanding of this is a good thing to have!</div> <bR> <bR> <div> <B>Basic operating principle – disturbed reticle LCOSS</B></div> <div> Back in WW2, as fighter speeds continued to increase, it was becoming more and more difficult to get hits with a fixed sight. In particular, the fixed sight was a poor aiming device for the high speed, high G turning engagements that were common once the battle was joined. The question was raised, "How can we show the pilot what his rounds are doing while he is turning?" The reasoning was that if the pilot knew where his gunfire was going, he then could maneuver to get the target to the same place. In our sims, tracers are used to show the bullet stream, as this next screenshot illustrates.</div> <div> <IMG SRC="7260d1c0.jpg" border=0 width="525" height="284" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> So good minds went to work. They began with the idea that the gun line and the nose of the aircraft were relatively close together. Since the nose of the aircraft can be seen as moving across the sky as the aircraft turns, it then became clear that the gun line must also be moving across the sky. In fact, practical experience in firing long bursts of tracers had long since demonstrated this. The problem boiled down to how to show this ‘tracer path’ to the pilot in a usable form.</div> <div> The answer was found in the unique properties of gyroscopes…once spun up, they tend to want to stay in place. If a force is applied to move them, they respond by precessing in a predictable manner. Someone asked, "‘What if this force is aircraft G? What will the gyro do?" And the answer was that the gyro would precess in a predictable manner and to a predictable degree. Voila’. All they had to do was to wire up the gyro so that it would send electrical signals that described its position. Now, when a force was applied to the gyro, it would precess and that precession could be measured. The precession had a direction and a magnitude…the greater the force, the larger the precession.</div> <div> Now, the good minds turned their thoughts to how to display this info to the pilot. Someone thought, "Combining glass….pipper…what if we made the fixed reflector sight reticle move!!" Another Voila’! The gizmo that made the sight image was hooked up to the gyro. Now, when the gyro precessed under G, the gizmo made the sight image move on the combining glass.</div> <div> The neat part of this is that the gyro precessed opposite the direction of turn…exactly opposite. It was recognized that this precession was in fact in the plane of motion of the fighter. They already knew the tracer path was in the same plane of motion. Bingo!! The precessing gyro produced a movable sight image that mimicked the behavior of the bullet path in a turn.</div> <div> <IMG SRC="727150b0.jpg" border=0 width="533" height="267" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> <B><U>Gyro Induced Reticle Movement</U></B></div> <div> Boy, they were hot on the track of a reliable gunsight at this point. The gyro precession gave them a way to, in effect, draw an imaginary tracer path on the combining glass. The only problem was that the tracer path went off into the boonies somewhere…it was hard to know how far away the rounds were at any point along the precession path.</div> <div> The answer to this problem lay in determining the time of flight (TOF) of the rounds. Since radar was in its infancy and was not very reliable at close ranges, the initial answer was to assume a certain range. Once that was agreed to, then it was a relatively simple matter to compute the TOF. This TOF number was now entered into the precession computation. The result was a precession path that had a finite length…for a given G and a given TOF, the precession path on the combining glass was a given amount. The sight gizmo was now designed to draw a reticle at the end of the precession path. When the aircraft was at one G, the reticle was located at the gun line, but, as G increased, the reticle moved away from the gun line …the greater the G, the further away from the gun line. Voila’ again!! The next figures show an F-86 sight, first at one G with the reticle on the gun line, and then in a right hand turn, with the reticle precessed left away from the gun line.</div> <div> <IMG SRC="7282b020.jpg" border=0 width="555" height="258" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> <I><B><U>Sight In Normal Position</U></B></I></div> <bR> <div> <IMG SRC="72928ef0.jpg" border=0 width="552" height="239" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> <I><B><U>Sight Precessed left</U></B></I></div> <bR> <bR> <div> The result was a sighting reference that demonstrated bullet behavior under G at a given range. All the pilot had to do was to get the target to fly under the pipper when the bullets were there also and, BOOM!!, he had a kill!! But, as you may suspect, it wasn’t quite that easy. There were some gotcha’s to be overcome. We’ll call these the inherent LCOSS errors.</div> <bR> <div> <B>Inherent problems in early disturbed reticle LCOSS</B></div> <div> There were immediate problems when the first LCOSS gunsights were introduced in WW2. The first problem area was the acceptance of the system by pilots and aircraft maintenance personnel. The system was mechanically complicated and required careful and exact maintenance by trained technicians. This was not often available. The system was delicate and easily damaged resulting in a LCOSS calculation that was inaccurate. Lastly, the system was challenging to use and demanded a relatively high level of pilot training...and this was often not the case in the war. As a result, the sight got mixed reviews from its pilots, with many refusing to use it...they went back to the fixed sight mode that they were familiar with.</div> <div> The second problem area had to do with the estimation of target range. The sights were calibrated for a selected range. If the pilot was not at that range, then the sight was ‘lying’ to him, and the firing solution would again be inaccurate. Hand in hand with target range was the issue of closure speeds. T he first LCOSS sights were built with the assumption that the attacker and target were co-speed, in other words, no closure. This was often not the case. If the attacker had considerable closure, then that changed the bullet TOF which then made the LCOSS calculation be in error. The result was again a pipper that did not represent actual bullet position for the assumed range.</div> <div> The third problem has to do with how long it takes a LCOSS computer to crank the numbers and arrive at a solution. This problem is inherent in all LCOSS regardless of their level of technology. As the pilot turns and the G’s increase, the LCOSS computer is busy generating the sight image position along the path of gyro precession. But this takes time…typically up to about one half second or more. The pilot must take this time…known as ‘settling time’…into account. This means that the pilot must give the sight a chance to ‘settle’ (stabilize) before he can count on the display being reliable. Picture the pilot pulling the pipper up to a target. Just as the pipper reaches the target, let’s freeze the picture. What do we see? We see the pipper on the target. But…and it’s a big but…the picture is not yet reliable. T he pilot must now hold the pipper on the target for the duration of the settling time. Then, and only then, is the sight picture reliable. Remember…the sight responds to aircraft G. Change the G, and you must reset the settling time clock. This is a hard and fast rule and one that has led to more missed firing opportunities than God has little green apples! The next figure is a cartoon taken from the USAF P-51 operating manual advising pilots to remember settling time.</div> <bR> <div> <B>LCOSS Implementation</B></div> <div> This section pertains to both types of LCOSS sights. This section could be subtitled, "What do I need to make the sight work?"</div> <div> When it comes to implementation, I want you to remember ‘The Big Three’…<B>in plane</B>…<B>in range</B>…and <B>in time</B>. Get these right, and you stand a good chance of downing your target. Get one or more wrong, and you might as well take up knitting!</div> <div> OK…so how do we use this thing to get a hit? We’ll get to the specifics later. For now, we just need to know that the sight is most effective if we accomplish the three items above. First, you want to get in plane with the target. That is where BFM comes into the equation. As we approach our target, we maneuver in three dimensions to reduce our aspect and angle off to end up behind the target. In doing so, we get into its plane of motion. The importance of the ‘plane of motion’ will be explained in the next section.</div> <div> Now, having gotten into the target’s plane of motion, we want to get into range. By this point in our discussion, I think we’ve said enough about the significance of range, so I’ll move on to the last of the ‘big three’…the idea of ‘time’.</div> <div> The ‘time’ that I am referring to, of course, is the settling time that the sight needs to arrive at a correct aiming solution. You must maintain a steady platform so that the LCOSS computer can do its job. You maneuver so that you can maintain the target under the pipper for the duration of the settling time and the required TOF. Do that, and the predicted bullet position (pipper) and the target should occupy the same space. But if you don’t allow the sight to settle and you don’t maintain a constant G while the sight is computing the numbers, then you are going to miss. Guaranteed.</div> <div> So much for the basic LCOSS theory. As you may suspect, there are some ‘what ifs’ and ‘yeah buts’ to what I’ve said…but the meat of the matter has been covered.</div> <div>  <IMG SRC="72a159a0.jpg" border=0 width="533" height="154" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> Our typical sim LCOSS will work just fine if you follow the guidelines above. </div> <div> <I><B><U>O'YEA DON'T FLY THROUGH DEBRIS!!!</U></B></I></div> <bR> <bR> <div> <B><U>INTRODUCTION PART 2</U></B></div> <div> Congratulations for having made it so far!! After countless words and diagrams, we finally are at the point where the ‘rubber meets the road’…or should I say where the ‘bullets meet the target’?!!</div> <div> In this last section, we are going to look at each type of sight ‘up close and personal.' Our objective is to describe the operation of these sights in such a manner that you can take the info and apply it directly to your favorite sim. All the little bits and pieces of info in Parts One and Two are going to be important in helping you understand how to get the gun on the target, so if you haven’t had a chance to look over those sections, it might be a good idea to do so before you start this one.</div> <div> We’ll begin with a quick review of the bullet stream concept. The single most important thing for you to get out of this is an appreciation for the three dimensional aspect of that bullet stream. If you can ‘see’ this concept in your mind, then understanding what is or is not a valid firing solution is a whole bunch easier.</div> <div> <B><U>Plane of Symmetry</U></B></div> <div> The plane of symmetry is another one of those terms that we use when we try to explain what we’re looking at when we use a gunsight. 99% of understanding and using a gunsight is in the understanding of what the gunsight display means with reference to the bullet stream. We have to establish a common frame of reference to do this. The plane of symmetry is a good place to start. The plane of symmetry is the vertical plane extending along the longitudinal axis and perpendicular to the rudder. It looks like this.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="72b16fb0.jpg" border=0 width="534" height="251" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 2 - Plane of Symmetry</B>A common way of visualizing the plane of symmetry is to use a line coming out of the top of our canopy that is perpendicular to the wings and fuselage. You can also think of the plane of symmetry as your lift line. Some like to use the vertical stabilizer to represent the lift line…that’s OK as long as the thing is vertical, and not canted off to one side or the other as in the F-18! The significance of this concept to gun employment is that the gun line lies in this plane, and that the bullet stream begins in this plane.</div> <div> <B><U>Plane of Motion</U></B></div> <div> The plane of motion is the direction our aircraft is going. You may ask if the plane of motion and the plane of symmetry are the same. The answer can be yes…or no. The issue is gravity. Anytime that gravity is exactly in alignment with the plane of symmetry (wings level, inverted or upright), the two planes are the same. But add a little bank, and gravity now becomes a force that takes the plane of motion away from the plane of symmetry. Why? Because our aircraft is affected by gravity, and the gravity force (or vector) has to be added to our lift line to get our actual plane of motion. It looks like this.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="72c2f3a0.jpg" border=0 width="559" height="314" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 3 - Gravity and the Plane of Motion</B></div> <div> Let’s shift our attention to the gun line. As we turn our aircraft, our gun line follows our nose across the sky. If our gun line was a pen, it would draw a line that would represent our actual plane of motion. As seen through the HUD, it would look like this.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="72d0aef0.jpg" border=0 width="522" height="239" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 4 - HUD View of the Plane of Motion</B></div> <div> Now let’s bring gravity drop back into the discussion…this time we’ll apply it to the bullet stream. Gravity starts acting upon the round as soon as it comes out of the barrel…the further the round flies, the further it drops. Looking at Figure 4 again, I’ll add a nominal gravity drop value to the end of the bullet stream. By connecting the two lines, we get a simplified representation of the bullet stream.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="72e60510.jpg" border=0 width="608" height="337" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 5 - Simplified Bullet Stream</B></div> <div> This is what it would look like from the cockpit. But this is a two dimensional view of the situation. To get a three dimensional view, we need to take a ‘God’s eye’ view from above. The next figure is a very exaggerated view of the situation. For the sake of illustration, we’ll say our gun fires five rounds as we turn. We open fire at position A and cease fire at position B. The five lines represent the paths of rounds 1 through 5. Please note the lines are straight. Rounds fired in a turn DO NOT curve or bend because we are in a turn. They fly straight and true as this figure shows.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="72f1e6b0.jpg" border=0 width="542" height="363" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 6 - Projectile Path</B></div> <div> But gravity does alter their flight path. That is why the HUD view shows a slight ‘drop’ if we could visually see the bullet stream. And we can. Our sims always show the bullet stream as a tracer path…by firing a long burst in a hard turn, you can easily see the effect of gravity on the bullet stream. Just keep in mind that the HUD view can be misleading since it is a two-dimensional picture. Take Figure 6 and file it away for safekeeping. You’ll need it as we get into the next section.</div> <div> As a final comment, please recognize that the ‘spread out’ nature of the bullet stream is caused by the shooter’s turn rate, ie G load. As turn rate increases, the bullet stream ‘thins out.'</div> <div> <B><U>Why do I need to know this?</U></B></div> <div> First, we talked about the plane of symmetry…then we went on to mention the plane of motion…and we finished up with words about the bullet stream. What’s the big deal? Here is the very simple answer. You can fire at a target and know that you have a good probability that many of your rounds will hit the target…or you can fire knowing that only a small number of rounds have a probability of doing so. To get yourself into the first group, you need to maneuver to get your bullet stream plane of motion into the target’s plane of motion. We call this a ‘tracking’ shot.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="73021530.jpg" border=0 width="545" height="339" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 7 - Aligning the Bullet Stream With the Target’s Plane of Motion</B></div> <div> If you are in the second group, and your bullet stream plane of motion intersects but does not lay in the plane of motion of the target (and sometimes, this is the only shot that you get), then your probability of getting a hit is much less. This is called a ‘snap’ shot.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="73138300.jpg" border=0 width="568" height="304" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 8 - Bullet Stream Crossing the Target’s Plane of Motion</B></div> <div> <B><U>The Big Three</U></B></div> <div> In Part Two, we discussed the three main components of a successful gun attack. These were getting in range, flying in the plane of motion of the target, and allowing for sight settling time. We’ll keep these in mind as we cover the types of sights and how to use them. The questions you want answers to are:</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.gif" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">How do I know when I am in range? </div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.gif" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">How do I know when I am in plane? </div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.gif" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">How am I sure that the sight has ‘settled </div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.gif" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">When do I open fire? </div> <div> And, before we go, here’s one last reminder that much of the effectiveness of a particular sight type lies in how much info it is getting about target behavior.</div> <div> <B><U>THE FIXED SIGHT AND HOW TO USE IT</U></B></div> <div> Fixed sights come in many forms. We are all familiar with the typical WW1 and WW2 sights.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="732e7b20.jpg" border=0 width="487" height="178" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 9 - WW1 Fixed Sight (Red Baron)</B></div> <div> <B><U><IMG SRC="733f3b90.jpg" border=0 width="499" height="185" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 10 - WW2 Fixed Sight (Janes WW2)</B></div> <div> <B><U><IMG SRC="73403a20.jpg" border=0 width="515" height="162" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 11 - WW2 Fixed Sight (EAW)</B></div> <div> But, the fact is that, as long as a sight has a gun line (cross) symbol, it can be used as a fixed sight. Look at these later model sights.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="73516840.jpg" border=0 width="534" height="132" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 12 - F-80 Fixed Sight (MiG Alley)</B></div> <div> <B><U><IMG SRC="736389e0.jpg" border=0 width="568" height="414" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 13 - F-105 Fixed Sight (Janes USAF)</B></div> <div> <B><U><IMG SRC="73737050.jpg" border=0 width="567" height="261" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 14 - F-16 Fixed Sight (Falcon 4)</B></div> <div> <B><U><IMG SRC="7383fc20.jpg" border=0 width="575" height="450" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 15 - F/A-18 Fixed Sight (Janes F/A-18)</B></div> <div> Why would a pilot want to go back to this type of aiming device when he has the option of using a LCOSS? Very simply because there are certain gun shot situations where the relationship between the shooter and target is changing so rapidly that the LCOSS setting time cannot be achieved. There are those times when a ‘point and shoot’ firing opportunity presents itself. Knowing how to do this can be your ‘ace card’…you can play it any time you want.</div> <div> How so, you may ask? Two ways…a tracking shot and a non-tracking or snap shot. Both of these attack types require a good understanding of the relationship between the gun line symbol, the bullet stream, and the target’s plane of motion. In either case, you want to minimize the lead angle solution variables by getting in close...short range means minimum projectile TOF which results in minimum lead for target motion and minimum gravity drop. Also, as long as you can get in close, target angle off will have minimum negative effect.</div> <div> <B><U>Fixed Sight Tracking Shot</U></B></div> <div> <B>Determining Target Range</B></div> <div> We’ve hit the concept of stadiametric ranging pretty hard so far. This will be your method of determining range in your sim, but there is one little problem. Few, if any, of our sims will tell us what the reticle or ring diameter is in mils, and if we do not know this, then computing target range is going to inexact at best. As a substitute, try this. For a fighter sized target, do not open fire until the target is at least one half the size of the reticle diameter. Cease fire when the target wingspan exceeds the reticle diameter.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="7393ff00.jpg" border=0 width="575" height="240" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 16 - Target In Range</B></div> <div> There are two main problems to solve in this type of gun attack…getting into the target’s plane of motion and predicting the correct lead angle (the open fire point).</div> <div> <B>Determining Target Plane Of Motion</B></div> <div> We do this by first considering the amount of G that we are going to use to track the target…low G or high G. In either case, there are target, HUD, and gunsight cues to help you.</div> <div> Look first at the target. Imagine a line extending from the target’s tail, through his nose, and out to the front. Think of this line as the target’s flight path…his plane of motion. You want to get your bullet stream on this line. Now visualize a line extending through the target’s wing. Call this the target’s wingline. We’ll use this line to represent target bank angle.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="73a40200.jpg" border=0 width="576" height="288" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 17 - Target Flight Path</B></div> <div> Pulling your pipper out in front of the target is not all that hard. Keeping it there is another matter. Here are the cockpit cues to make this a little easier. The key to success lies in your ability to match the target’s angle of bank. We do that by aligning our wingline with the target wingline.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="73b2e0d0.jpg" border=0 width="558" height="269" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 18 - Matching The Target’s Bank Angle</B></div> <div> For low G situations, use your cockpit structure to define your wingline. Some gunsights have a tab at the 3 and 9 o’clock position on the sight reticle. You can also use the top of the HUD to approximate your wingline. You want to align these references with the target’s wingline. It looks like this.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="73c3bee0.jpg" border=0 width="571" height="238" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 19 - Fixed Sight Tracking - Low G</B></div> <div> For high G situations, use the 6/12 o’clock tabs if available. If not, other usable visual cues include having the top of the HUD perpendicular to the target’s fuselage line or using the sides of the HUD to line up with the target’s fuselage.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="73d3a3d0.jpg" border=0 width="570" height="317" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 20 - Fixed Sight Tracking - High G</B></div> <div> <B>Determining Sight Settling Time</B></div> <div> Not applicable! Since the sight is a ‘fixed’ reference, ie non-moving, there is no settling time.</div> <div> <B>Determining The Open Fire Point</B></div> <div> The major difficulty in tracking with a fixed sight is getting the lead for target motion right. Since the primary variables of range, closure, and angle off are infinite in number, all we can do is employ an educated guess. By this time it is clear that the amount of required lead is reduced if we can minimize range and angle off. We should try to do that.</div> <div> We can also get a feel for the lead required by looking at other sim’s sight displays that offer a LCOSS. Use these sim’s reticle position or funnel display to gain an appreciation of open fire points for various turn rates and G loads. You will find that the displacement of the reticle or funnel reference varies directly with G load (turn rate). Here are a couple of screenshots that show the lead points necessary for typical angle off situations.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="73e25320.jpg" border=0 width="549" height="306" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 21 - Low G Open Fire Point</B></div> <div> <B><U><IMG SRC="73f2a610.jpg" border=0 width="554" height="353" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 22 - High G Open Fire Point</B></div> <div> These pictures give you a feel for where the open fire point is. We then take that ‘mental picture’ and translate it to our fixed sight HUD. Here are two views of typical fixed sight firing points showing the reticle/pipper in similar lead positions.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="74035350.jpg" border=0 width="565" height="309" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 23 - Low G Open Fire Point</B></div> <div> <B><U><IMG SRC="74136280.jpg" border=0 width="566" height="296" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 24 - High G Open Fire Point</B></div> <div> We place the gun line in front of the target and vary our G to allow the target to move towards the approximate lead point. One technique is to start out with a little more lead than necessary…then relax G slightly to move the target ‘forward’ towards the gun line. As the target nears your lead point, squeeze and hold the trigger down. Maintain your attitude steady and allow the target to continue to move forward slightly. By letting your aim point drift to the target, you are allowing for small errors in your lead estimation.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="7423a210.jpg" border=0 width="570" height="289" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 25 - Tracking With A Fixed Sight</B></div> <div> <B><U><IMG SRC="7433b860.jpg" border=0 width="571" height="390" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 26 - Tracking With A Fixed Sight</B></div> <div> <B><U><IMG SRC="7443c240.jpg" border=0 width="572" height="292" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 27 - Tracking With A Fixed Sight</B></div> <div> <B><U>Fixed Sight Snap Shot</U></B></div> <div> A ‘snap shot’ is when the shooter fires without attempting to track the target. It is similar to skeet shooting in that the shooter fires a burst across the target’s flight path. This results in fewer rounds having a chance to hit the target. Because of this, the snap shot has a lower probability of kill than a tracking shot. But a snap shot is better than no shot at all…and in an intense, swirling knife fight, it may be the only shot you get.</div> <div> <B>Determining Target Range</B></div> <div> The dynamic nature of the snap shot situation means that the target will not be in the HUD area prior to your pulling the trigger. Consequently, you will not be able to use the reticle to range with. Instead, you will have to estimate target relative size, always keeping in mind that the objective is to take a close range shot.</div> <div> To achieve this close range, you will have to pull your nose out well in front of the target. If you underestimate this lead point, then the target will cross your nose too far away. While no two situations are the same, we can suggest a ‘window’ that will put you in the ballpark. From then on, practice and experimentation will lead you to good results. Here is a forward view with a ‘window’ drawn that shows the approximate area that you would want to place the target as you pull your nose out in lead. Think of the edge of the monitor as the beginning of the window. The end of the window is about one half the distance between the monitor edge and the reticle.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="7453b380.jpg" border=0 width="571" height="312" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 28 - Snap Shot Lead Window</B></div> <div> By using this much lead, you should be able to arrive at a firing point that meets our close range goal.</div> <div> <B>Determining Target Plane Of Motion</B></div> <div> Our next objective is to get our gun line into the target’s plane of motion. The gun line reference, however, is in the HUD. The target, when it is in the ‘window’ is no where near the HUD. So, how do we get into the target’s plane of motion? We use cockpit references.</div> <div> Here is one technique. Go to the forward view in your sim. Fly wings level. Locate the gun line. Now, look to the sides of the HUD area for cockpit or HUD structure that are in approximate alignment with the gun line. The further away from the gun line, the better. What we want to do is to draw a line from this reference to the gun line. This line will be our target flight path reference when our wings are level with the target’s flight path.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="74645620.jpg" border=0 width="581" height="354" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 29 - Snap Shot Gun Line References</B></div> <div> After we have pulled our nose out in lead, we will level our wings with respect to the target’s flight path. Visualize this flight path as an extension of the target’s fuselage line. In your mind, try to see the ‘big picture’ by projecting this flight path line across your nose.</div> <div> Now, with our wings level with this line, we pull our nose up to raise the gun line up (or lower our nose to move the gun line down) to superimpose our gun line with the target flight path line. Use the snap shot gun line references in Figure 29 to help get your gun line in the proper position.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="747116c0.jpg" border=0 width="529" height="364" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 30 - Target Flight Path Projection</B></div> <div> <B>Determining Sight Settling Time</B></div> <div> Again, not applicable for fixed sight gun employment.</div> <div> <B>Determining The Open Fire Point</B></div> <div> We used the idea of a ‘window’ to represent the lead point when pulling the nose out for a snap shot. We’ll now return to that concept and give you a ball park visual picture of the open fire point. First, one additional point regarding fixed sight technique.</div> <div> The gun does not know your angle of bank relative to the target. I have suggested the idea of using cockpit references to line up the gun line with the target flight path as a matter of simplicity and convenience. There is absolutely no requirement for you to be wings level relative to the target’s flight path.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="7491c330.jpg" border=0 width="540" height="307" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 31 - Target Flight Path</B></div> <div> We drew the roll out window using the wings level HUD as a reference. This resulted in two ‘windows’…one on the right and one on the left of the HUD gun line. If we take our bank angle out of the picture, we can draw the lead window as a circle or ‘band around the gun line. The next figure shows this. For a good lead angle, position the target no closer to the HUD than the red circle.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="74a25070.jpg" border=0 width="549" height="263" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 32 - Roll Out Lead Circle</B></div> <div> The only thing the shooter has to do is roll out with his gun line in the target’s future flight path. This same concept can be applied to the open fire point. The open fire point then becomes a circle or ‘band’ around the gun line. Regardless of his bank angle, when the target enters the open fire circle, the shooter pulls the trigger.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="74b34050.jpg" border=0 width="564" height="261" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 33 - Open Fire Window</B></div> <div> And now the foot-stomper. <B>This is a one G technique</B>. You want to get the gun line in the target plane of motion and then hold it there. As the target approaches the open fire point, you want to make sure you are at one G. Why? To concentrate your bullet stream. You are literally ‘strafing’ a point in the sky that the target will fly through. The open fire point is a band to account for variances in the rate of target motion across your nose (LOS rate). The outer edge is for a high LOS rate, the inner for slower LOS rates.</div> <div> So here’s the technique. Pull your nose out in front of the target using canopy references to get into the target’s flight path. Raise or lower your nose to get the gun line on the target flight path. Relax G. Is the gun line still in the target’s flight path? If not, make an adjustment. Relax G again. Hold the gun line in the target flight path, and as the target enters the open fire window, double check you are at one G and then pull the trigger.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="74c2c4e0.jpg" border=0 width="556" height="334" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 34 - Snap Shot Lead PointFig 34 - Snap Shot Lead Point</B></div> <div> <B><U><IMG SRC="74d28370.jpg" border=0 width="552" height="311" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 35 - Snap Shot Firing Window</B></div> <div> <B><U><IMG SRC="74e28050.jpg" border=0 width="552" height="261" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 36 - Snap Shot Result</B></div> <div> OK…so much for the fixed sight…it’s on to the two LCOSS sight types.</div> <div> <B><U>THE DISTURBED RETICLE SIGHT AND HOW TO USE IT</U></B></div> <div> I guess the place to start is to explain what ‘disturbed reticle’ means! Let’s take the ‘reticle’ part first. The reticle (or reticule, as some texts spell it) is the name of the circle that many sight images look like.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="74f2a0d0.jpg" border=0 width="554" height="269" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 37 - F-4 Gunsight</B></div> <div> In the center of the reticle is a small dot known as the ‘pipper.' When a fighter pilot uses the term pipper, he usually is referring to the reticle as a whole with specific emphasis on the center dot. Some reticle sight images have a smaller circle within the outside reticle, usually at the one half radius point.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="750abaa0.jpg" border=0 width="427" height="170" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 38 - F-105 Double Reticle</B></div> <div> Early reticles were not circles at all, but instead were a series of small diamonds arranged in a geometric pattern around the pipper. WW2 and Korean War sights were often of this type. Some referred to this display as a ‘circle of diamonds.'</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="751c7cf0.jpg" border=0 width="455" height="207" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 39 - Circle of Diamonds Reticle</B></div> <div> In some sights, this circle of diamonds was adjustable in size. The gizmo that made the sight image had controls that the pilot could adjust. He could set aircraft wingspan as well as desired range. The result was a reticle or circle of diamonds whose diameter represented how big the target’s wingspan should be for a desired range.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="7521f260.jpg" border=0 width="543" height="294" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 40 - MiG Alley Sight Control Panel</B></div> <div> Some fighters had a twist grip on the throttle that was linked to the sight image gizmo. The pilot would set the target wingspan into the sight control panel. Then, once the pilot was behind a similar target, he would twist the throttle shaft to either open up or close the reticle diameter until it matched the wingspan of the target. The gunsight computer used the relative size of the reticle, in h and yaw. Pitch means G…pushing or pulling on the pole. Yaw means rudder…pushing the rudder pedals one way or the other. In a one G condition, the reticle will be close to the fixed gun line. Pulling back on the stick cauconjunction with the target wingspan, to compute a range, so once the pilot superimposed the reticle over the target, the gunsight ballistics computer had a range to then use to compute a TOF. The TOF value was then used to compute gravity drop.</div> <div> So much for the description of the reticle. Now let’s talk about this term ‘disturbed.' What is this word referring to? Let’s go back to where we were talking about gyroscopes. We said that a gyroscope would react if a force was applied to it. This reaction (precession) is the gyro being ‘disturbed’ from its static position. In gunsight terms, the word ‘disturbed’ refers to reticle precession behavior of gyro-based sights. So…a disturbed reticle sight is any sight using gyro precession as the means of determining reticle position.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="7533b210.jpg" border=0 width="571" height="289" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 41 - Gyro Precession</B></div> <div> Next question. What forces cause the gyro to precess? Two forces…pitcses the reticle to move towards the bottom of the HUD or combining glass. If the pilot then relaxes G, the pipper will move back up towards the gun line position. If the pilot pushes negative G, the reticle will move above the gun line position.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="7543fb60.jpg" border=0 width="575" height="438" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 42 - Positive G Funnel</B></div> <div> <B><U><IMG SRC="75544620.jpg" border=0 width="580" height="354" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 43 - Negative G Funnel</B></div> <div> If the pilot pushes the rudder while maintaining one G, the nose will yaw in the direction of the rudder application. The reticle will move opposite this movement away from the gun line position. Right rudder…the reticle moves left, and vice versa.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="7564a760.jpg" border=0 width="586" height="374" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 44 - Yaw Inputs</B></div> <div> In this manner, we see that reticle movement is strictly a function of aircraft pitch or yaw inputs. The reticle movement has nothing at all to do with the presence or absence of a target. As we explained before, the magnitude of the reticle movement can be controlled by a range input to the gunsight computer (TOF again) but the movement itself is only due to aircraft pitch and yaw forces.</div> <div> In earlier paragraphs, we covered the theory of how the LCOSS represents an aiming solution. Rather than repeat that, let’s take the idea one step further and talk for a bit about what this disturbed reticle position means to you as the pilot. In doing so, we’ll get a better understanding of some of the limitations of the system.</div> <div> Let’s recall again what the sight is doing. We are moving our nose…the gun line follows this movement. We use a gyro to display this movement on the combining glass in the form of a pipper that is displaced away from the fixed gun line position (the nose of the airplane) in a direction opposite our plane of motion. The pipper is positioned on the imaginary precession line as a function of range (TOF).</div> <div> OK. Now pay real close attention to this next part, because it’s the meat of the subject.</div> <div> Let’s go into a turn and hold a constant airspeed and G. What happens to the sight? It depresses opposite our plane of motion. Where’s the pipper? It’s at the desired range position. Where’s the target? I don’t know…who said anything about a target? With the basic LCOSS, you don’t need a target. The LCOSS computer is not getting any target info because we are not giving it any (other than an assumed range). The LCOSS doesn’t need target info other than a range input. WHY? Because all it is doing is displaying bullet position based upon your plane of motion.</div> <div> The sight is saying something to you, and here it is:</div> <div> <B>If you maintain a constant plane of motion and hold your G steady for the required settling time, the pipper will represent where the bullets are NOW that were fired one TOF ago.</B></div> <div> Pound the table, people…that statement is the principle of a disturbed reticle LCOSS wrapped up in a neat little ball.<B> </B>The LCOSS is showing you the past, not the future. It’s not telling you that if you fire NOW that you will hit the target…nope, it’s telling you only one thing. If you had fired one TOF ago, you would be now seeing a hit.</div> <div> Is that 100%, absolutely clear? Don’t go any further if it is not. Re-read this section until you have it down cold.</div> <div> <B><U>Disturbed Reticle Tracking Shot</U></B></div> <div> <B>Determining Target Range</B></div> <div> All disturbed reticle LCOSS have a range input. For aircraft that do not have a radar (such as WW2 sims), the range input to the ballistics computer is a fixed value. The same is true of modern aircraft when the radar is not operating or the pilot does not have a radar lock on.</div> <div> Similarly, if the disturbed reticle LCOSS is a funnel display, the sight not only assumes a fixed wingspan, but may also display additional symbology to indicate target range. The Janes USAF ‘Bullet At Target Range’ (BATR) symbol is a good example of this. The following chart shows typical assumed wingspans found in today’s sims.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="757341a0.jpg" border=0 width="564" height="282" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 45 - Typical Assumed Wingspans</B></div> <div> Consequently, it is the shooter’s responsibility to be at the proper range when using the sight. The easiest way to do this is to use the funnel or reticle match using stadiametric principles.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="758221f0.jpg" border=0 width="546" height="287" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 46 - Typical LCOSS Funnel Display</B></div> <div> If the shooter has a radar lock on, then the problem gets much simpler. Now, the LCOSS is getting a range input that it can use to correctly compute the lead angle and gravity drop components. Depending on the sight type, the other assumptions (constant range, no overtake, etc) may still apply. The next two pictures show typical LCOSS reticle displays. The Janes USAF reticle includes the range analog bar. The Falcon 4 picture shows the reticle display for a no radar lock situation. In this example, the reticle indicates a range of 1500 feet. The Falcon 4 LCOSS reticle with a radar lock looks exactly the same…however the reticle will now represent a firing solution for the exact target range.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="75927480.jpg" border=0 width="551" height="328" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 47 - Reticle Range Analog Bar - Janes USAF</B></div> <div> <B><U><IMG SRC="75a34200.jpg" border=0 width="564" height="288" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 48 - No Lock LCOSS Pipper - Falcon 4</B></div> <div> <B>Determining Target Plane of Motion</B></div> <div> The visual references for getting into the target’s plane of motion are the same as they were for the fixed sight. In addition, with the disturbed reticle LCOSS, you may use the displaced pipper or funnel axis as an indication of your plane of motion. The line from the gun cross to the pipper, or the axis of the funnel, represents your flight path. Use this as a guide in bank control to match the target’s flight path.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="75b1b4d0.jpg" border=0 width="539" height="333" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 49 - LCOSS Plane of Motion Cue</B></div> <div> The problem of getting into the target’s plane of motion uncovers another one of those ‘great truths’ of A2A gun employment. Here it is:</div> <div> <B>Do not try to ‘fly’ the pipper (or funnel) to the target. Instead, use traditional BFM to get the target positioned in the approximate center of the HUD with your closure under control and your fuselage aligned with the target. During this time, ‘ignore’ the pipper or funnel. In your mind’s eye, ‘turn off’ the sight display. Once the target is in a stable position in the HUD, then (and only then) compare the pipper or funnel to the target.</B></div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="75c40600.jpg" border=0 width="576" height="352" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 50 - BFM the Target Into the HUD</B></div> <div> Once you have the target stabilized, then you can compare the pipper or funnel to the target. Determine what kind of correction you need to make. Then, again ‘turn off’ the sight while you reposition the target in the HUD.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="75d475e0.jpg" border=0 width="583" height="350" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 51 - Compare Pipper To Target</B></div> <div> <B><U><IMG SRC="75e4b7a0.jpg" border=0 width="587" height="378" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 52 - Adjusted Tracking Position</B></div> <div> <B>Determining Sight Settling Time</B></div> <div> Sight settling time varies between sight types…anywhere from less than one half a second to a full second. The secret to satisfying sight settling time requirements lies in the concept of BFM’ing the target into the HUD before you bring the pipper or funnel into the picture. By stabilizing the target, you are automatically settling the sight. After making the final corrections to pipper or funnel position, then stabilize momentarily before firing. Here’s a tip. Count to yourself, "One potato, two potato…", then pull the trigger!! That should do the trick!</div> <div> <B>Determining The Open Fire Point</B></div> <div> If we have accomplished the first three items above…gotten in range, then in plane and lastly, allowed enough settling time, then we pretty well have the open fire point under control.</div> <div> The techniques to get to this point are much the same as they were for the fixed sight tracking shot. The main difference lies in the fact that the lead angle computation is now more accurate, and as such, the shooter does not have to allow for as much error in the open fire point.</div> <div> In the final stage of positioning the pipper or funnel, the shooter makes a last correction to his back pressure to move the pipper to the target. Once the sight aiming point is superimposed over the target, the shooter waits for the necessary settling time and then fires. A technique that works well is the ‘track - shoot – track’ concept. Remember that the sight picture is essentially a ‘picture of the past’…it’s telling you that what you are seeing is a picture of bullet position one TOF ago. The ‘track - shoot – track’ concept takes this into consideration in the following manner.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="75f5d530.jpg" border=0 width="605" height="339" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 53 - Track - Shoot - Track</B></div> <div> Maintain a constant G and attitude as you hold the pipper over the target. Squeeze - don’t jerk – the trigger as you continue to hold your G and bank attitude constant. Release the trigger and continue to track the target for a moment. Then be ready to get out of the way of the target debris!</div> <div> This technique is similar to the ‘follow through’ emphasis common in skeet shooting. It encourages good pipper discipline.</div> <div> <B><U>Disturbed Reticle Snap Shot</U></B></div> <div> The disturbed reticle LCOSS can be used for a snap shot attack, but the technique is a bit more complicated than what it was for the fixed sight. In the discussion of the fixed sight, we advocated a one G technique for the snap shot. You can do the same for the disturbed reticle sight, but if you do, then you are essentially using the LCOSS as a fixed sight. There is nothing wrong with this, and, in fact, this remains a very good technique, but the LCOSS also offers you the chance to snap shoot with G on your aircraft.</div> <div> The basis for this technique rests again on the idea that the reticle position is an indicator of bullet position fired one TOF ago. If we can maneuver such that the target will fly into the pipper one TOF after we pulled the trigger, then we have a good chance of getting a hit.</div> <div> As always with a disturbed reticle sight system, the controlling factor is maintaining a constant G and steady firing platform as you position the pipper. I am using the term ‘pipper’ in this paragraph because the funnel display is more difficult to snap shoot with. The funnel can be used, but, because of the difficulty in estimating range, the actual display is harder to interpret in an out-of-plane shooting position.</div> <div> <B>Determining Target Range</B></div> <div> The LCOSS will have either a fixed range or radar range input. Because of the highly dynamic nature of the snap shot geometry, ranging errors are to be expected. You can reduce their significance by reducing the firing range.</div> <div> The next figure shows a specialized snap shooting sight from Falcon 4. The tracer line is your bullet path. The position of the reticle is determined by radar ranging, or in the absence of a lock on, the reticle is fixed at a range of 1500 feet. The tick marks are TOF markers for .5, 1.0, and 1.5 seconds.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="7603b230.jpg" border=0 width="571" height="291" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 54 - Falcon 4 Snap Shot LCOSS</B></div> <div> <B>Determining Target Plane Of Motion</B></div> <div> In the fixed sight discussion of the snap shot, we used a one G technique that used cockpit and HUD references to align the target’s flight path with our gun line. But the advantage of a disturbed reticle system is that it attempts to show bullet position at any G. Can the disturbed reticle sight be used for a snap shot when you are pulling more than one G?</div> <div> The answer is yes. But, the level of difficulty goes up quite a bit. Instead of flying the target through the gun line position, you are now going to have to fly the target through the displaced pipper position. The trick is how to get the target to fly through the pipper. Remember, you and the target are flying two different flight paths! The LCOSS snap shot when you are pulling G is an out-of-plane maneuver! Here’s how to do it.</div> <div> Begin with a substantial amount of lead. Get your nose out in front of the target…outside the edge of the forward canopy bow in most cases. The picture that you want to visualize is that you are going to drag your pipper across the target’s flight path. Your objective is to have the pipper cross that flight path the same time as the target.</div> <div> <B>Determining Sight Settling Time</B></div> <div> With your nose in lead, try to stabilize your G load as you position the pipper in the projected target flight path. The steadier you are with your G control, the less settling time you will require. Remember that the sight responds to your G inputs, so any last second pitch movement may result in an invalid pipper position.</div> <div> <B>Determining The Open Fire Point</B></div> <div> This is not called a snap shot for nothing! The open fire point comes and goes in a heartbeat! Think of yourself as a one-handed juggler…you have two balls up in the air…the pipper and the target. You are going to try and catch them both at the same time. Can it be done? Yes, but not easily!! The next figure shows the situation.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="76116660.jpg" border=0 width="534" height="358" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 55 - The Snap Shot Plan View</B></div> <div> Your objective is to fire as the target flies into the pipper. Increase your chances by raking your bullet stream across the target flight path. Don’t try to fire the magic single bullet…instead account for lead errors and out-of-plane errors by firing as you pull your pipper through the target flight path.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="7624f330.jpg" border=0 width="591" height="307" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 56 - Open Fire Point</B></div> <div> OK!! It’s now time to move on to the Director LCOSS. In many respects, the director sight is similar in employment to the disturbed reticle sight.</div> <div> <B><U>THE DIRECTOR SIGHT AND HOW TO USE IT</U></B></div> <div> Well…if that is the case, then I had better tell you what those similarities are…right??</div> <div> OK!! Fair enough!! The most obvious similarity is that the director aiming symbol is displaced away from the gun line. The next similarity is that the director system uses a range input…usually radar…some, like Flanker 2, may also use a Laser/IR tracking system. And last…the director system needs settling time to minimize radar tracking errors.</div> <div> End of story. Past this point, everything is different. Really different.</div> <div> Here it is again in a nutshell. Disturbed sight systems attempt to show you the past…<B>bullet behavior one TOF ago</B>. Director systems attempt to show you the future…<B>bullet behavior one TOF from now</B>.</div> <div> As you can easily recognize, this is not insignificant.</div> <div> Let’s expand the explanation of a director system some more. Director systems display a sight picture that says this, "If you pull the trigger now, you will hit the target". This means the bullet fired now will hit the target after one TOF. Inquiring minds might ask…"Just how does the director system know what’s going to happen in the future?"</div> <div> The answer lays in one major assumption…the target is going to keep on doing what it is doing for the next few moments.</div> <div> To explain this, let’s use the following example. We’ll start with a situation where we are tracking a target. We are in plane with the gun line at the correct lead point. Here is a drawing of the basic gunnery solution.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="7632a5c0.jpg" border=0 width="554" height="348" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 57 - Basic Gunnery Solution – No Pipper</B></div> <div> Let’s return to our initial discussion of gun ballistics. This drawing represents the solution…the ONLY solution. Any additional aiming references that we include in the basic HUD picture only serve to simplify the aiming problem. Regardless of what type aiming references these are, they do NOT change the basic ballistics. The point that I am trying to make is this. The disturbed reticle sight is not ‘better’ than the fixed sight, and the director sight is not ‘better’ than the disturbed reticle sight. The fixed, disturbed reticle, and director symbology are just different ways of showing the pilot what the basic gunnery solution LOOKS like. Advanced sight types may be easier to use, but they are not more accurate.</div> <div> Let’s redraw Figure 57 and now include a pipper over the target. This new picture can be either a disturbed reticle sight or director sight display.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="764323b0.jpg" border=0 width="562" height="315" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 58 - Basic Gunnery Solution – With Pipper</B></div> <div> If it is seen as a disturbed reticle sight display, then the picture is saying, "If you had fired one TOF <B>ago</B>, the rounds would be impacting the target <B>now</B>." What does this display say about what will happen if you fire now? Not much. The disturbed reticle theory predicts that if your flight path does not change, you will hit the target if you fire now…assuming the target is still under the pipper. But, since the disturbed reticle sight is not computing target position, it has no way of knowing where the target will be. So, this display is a nice picture of what might have been, but as far as what may happen if you fire now, it’s a pure guess.</div> <div> What is the director display saying to you? Simply, that if you fire <B>now</B>, the target will be hit one TOF from now. Does this sound like the director sight is trying to predict the future? Yes. That is exactly what it is trying to do. It does this by taking advantage of its radar lock on. The sight computer gets target flight path data…speed, direction, turn rate, closure…and puts all of this together to predict a future target position. How far into the future? One TOF. It then generates a pipper display that is a steering command to get you to point the gun at this predicted point in space.</div> <div> The bottom line is that regardless of the sight type, the gun is still pointed at the same point in the sky to hit the target.</div> <div> As far as the director sight goes, what does all this mean? To put it bluntly, it means, ‘What you see is what you get.' Put the pipper on the target, fire, and you’re a hero. That’s how it is supposed to work. Could we be so lucky? Probably. Especially as long as the following conditions apply.</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.gif" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">The target does not change its flight path after we pull the trigger. (If it does, all bets are off.) </div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.gif" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">The sight has enough settling time to reliably compute a valid solution. </div> <div> Fortunately, given typically short TOFs, these conditions are not unrealistic. Director sights are very lethal. You want yours to be equally lethal in your sim. Let’s talk about how to do that.</div> <div> <B><U>Director Sight Tracking Shot</U></B></div> <div> <B>Determining Target Range</B></div> <div> Not a biggie!! We already know that the director system relies on a radar or IR/laser lock on. Accurate ranging is a given in this sight system. The next two figures show how range is displayed in the Flanker 2 and Janes F/A-18 sims. Both use a reticle analog bar, but the bar is interpreted differently. The Flanker range bar moves counter-clockwise and is an indicator of relative range. The range bar starts at the 12 o’clock position and indicates ‘maximum range.' It then moves around the reticle to reach a ‘minimum range’ position between the one o’clock and 12 o’clock positions.</div> <div> The Janes F/A-18 range bar is more specific. The bar also moves counter-clockwise starting from the 12 o’clock position. Tick marks representing thousands of feet range are around the circumference of the reticle. In addition, the HUD has a range readout.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="76524e10.jpg" border=0 width="548" height="225" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 59 - Director Sight Range Cue - Flanker 2</B></div> <div> <B><U><IMG SRC="76624fe0.jpg" border=0 width="548" height="254" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 60 - Director Sight Range Cue - F/A-18</B></div> <div> <B>Determining Target Plane of Motion</B></div> <div> Use the very same techniques to get into the target’s plane of motion that you used with the two previous sight systems.</div> <div> Use BFM to get the pipper and the target into the same general area of the HUD. Then, smoothly use aileron and pitch to ‘fly’ the pipper to the target. The pipper indicates the direction to fly to get the gun line on the target. The next figure shows this.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="767278d0.jpg" border=0 width="551" height="397" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 61 - Director Sight Steering Cues - Flanker 2</B></div> <div> <B><U><IMG SRC="7682a840.jpg" border=0 width="554" height="388" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 62 - Director Sight Steering Cues - F/A-18</B></div> <div> <B>Determining Sight Settling Time</B></div> <div> Allow for the same amount of settling time that you do with a disturbed reticle sight.</div> <div> <B>Determine The Open Fire Point</B></div> <div> This one’s a no-brainer. Assuming you have done all of the above, when the pipper display indicates a firing solution, then blast away. If all is well, the sight is like a ‘death dot’…anything it touches is hit.</div> <div> One might ask, "How do I know that I have a firing solution?" This is a good question. The pipper does not always indicate bullet position. Remember the pipper is a steering command…it is telling you which way to steer to get the gun line on the target. Fortunately, most director systems will include a ‘shoot’ cue that tells you that you have a valid firing solution. So, fly the pipper to the target and double check that you have the shoot cue before you fire.</div> <div> The Flanker director sight uses two shoot cues. First, the ‘in range’ "LA" cue will appear. The target will have an aiming circle around it. Your second ‘shoot cue’ will be anytime you superimpose the reticle over the aiming circle once the ‘LA’ range advisory is in view.</div> <div> The F/A-18 director sight uses the word "SHOOT" to indicate to the pilot that the sight has a valid solution. This "SHOOT" cue will not appear until you get the pipper on the target.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="76934110.jpg" border=0 width="564" height="273" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 63 - Director Sight Shoot Cue - Flanker 2</B></div> <div> <B><U><IMG SRC="76a0e3d0.jpg" border=0 width="526" height="317" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 64 - Director Sight Shoot Cue - F/A-18</B></div> <div> Pretty neat, eh?!!</div> <div> And it is. But the director sight is very dependent on a number of variables and assumptions that sometimes are not too compliant. Future target behavior is number one on this list. Fortunately, if we fire at close range, the short TOF makes it improbable that the target will be able to maneuver away from our bullet path.</div> <div> Great!! So, how about using the director sight in a snap shot situation?</div> <div> <B><U>Director Sight Snap Shot</U></B></div> <div> Let’s dispense with the rocket science, and just say that the director sight is designed for a tracking solution. Its reliance on a radar or IR/laser lock on and predictable target behavior all conspire to make snap shots difficult. Remember, the pipper is not an indication of bullet position…it is a direction steering symbol only. It is saying that if the shooter can place the pipper over the target and fire, then he will get a hit. That’s just fine…for a disturbed reticle LCOSS where the pipper indicates bullet position. But for a director sight, in a snap shot situation, the position of the pipper becomes very unpredictable. And, because the target is in the gun line for such a small amount of time, settling time and tracking errors are common place. This is not to say that a snap shot cannot be done using the director sight…it’s just much, much harder! Here are some tips for how to do this with the Flanker and F/A-18 director sights.</div> <div> <B>Flanker 2 Snap Shot</B></div> <div> Pull the nose out in lead as you would with any sight. If possible, try to level your wings with the target’s flight path…this makes the solution easier to see. Select a view that will allow you to see in the direction of the target. Padlock will work well. You can also use the forward view and slew your look angle towards the target.</div> <div> In your view, you will have three items to work with…the target, the aiming circle and the reticle. Initially, the reticle may not be in view until you reduce your range. Project the target’s flight path forward across your HUD. Raise or lower your nose to line up the reticle with the aiming circle.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="76b28440.jpg" border=0 width="552" height="324" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 65 - Initial Nose Position</B></div> <div> Adjust your heading to close your range. Be ready to see the target move rapidly across your nose. Fine tune your nose position to align the target flight path, aiming circle, and reticle. Open fire as the target approaches the aiming circle and continue to fire until the target flies through the reticle.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="76c1f550.jpg" border=0 width="543" height="341" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 66 - Open Fire Point</B></div> <div> <B>Janes F/A-18 Snap Shot</B></div> <div> Pull your nose out and fine tune your nose position as described in the Flanker section. You will again have three references…the target, the reticle, and the approximate gun line. The ^ symbol immediately above the gun cross symbol is the approximate gun line.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="76d282b0.jpg" border=0 width="552" height="299" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 67 - Initial Nose Position</B></div> <div> Open fire as the target approaches the reticle.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="76e0a4b0.jpg" border=0 width="522" height="331" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 68 - Open Fire Point</B></div> <div> You do have an alternative. Disregard the LCOSS symbols and use a fixed sight technique. For Flanker 2, return your sight to the funnel display by breaking your radar lock. For F/A-18, use the ^ symbol as your gun line.</div> <div> <B><U>CONCLUSION</U></B></div> <div> <IMG SRC="76f1ed70.jpg" border=0 width="542" height="215" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> This has been long and involved, but I hope you understand gunsights better now than you did before. Nothing has changed since the Red Baron took to the air. Get in close, steady your aim, and fire a good burst.</div> <DIV ALIGN="LEFT"></DIV> <div> <B><U><IMG SRC="7701d170.jpg" border=0 width="541" height="279" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <div> <B>Fig 69 - Good Hunting!!</B></div> <bR> </td> </tr></table></body>