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How to Live and Die in the Virtual Sky
by Dan "Crash" Crenshaw, www.deltahawks.org
CHAPTER 3:
OFFENSIVE BFM, Part 2
Figure 3-4
Figure 3-4 shows the difference in Turn Radius with all factors being equal (speed, Cockpit G, etc) except the direction of the vertical turn. It should also be noted that aircraft in the downhill turn has a higher Turn Rate as well.
TURN CIRCLE
Turn Circle has two basic definitions:
"The path a fighter flys through the sky when it turns" and "The area you must position yourself for Offensive BFM to be effective."
When a bandit starts to evade and turns, he creates a Turn Circle. To effectively attack him without becoming the prey yourself, you must get "inside" his Turn Circle. The reason for this is, if you begin your attack outside this circle, the bandit has enough "Turning Room" (Turning Room is the offset and distance between you and the bandit) to get back around on you and possibly take control of the fight. Turning Room can be Vertical, Horizontal or a combination of the two.
Starting Offensive BFM maneuvers outside of the Turning Circle allows the bandit to continue his turn and cut off any Turning Room you may have been able to get. The up side to this is that you probably have more energy than the bandit. The down side is now you are in a turning fight. Going Vertical while outside the Turning Circle to acquire Turning Room will usually put you into a very compromising position and should be avoided.
Any maneuvers you make outside of the Turn Circle will delay you from entering the Turn Circle. You want to get into the Turn Circle as fast as possible with no delay.
How do you know when you are in or out of the Turn Circle? To make your decisions on when to turn and what type of turn to do, you really need to know this. Watch the bandits turn rate. Will it allow him to turn fast enough to put his nose on you? If so, you are outside the Turn Circle. This will lead to a Head On BFM situation which we will cover in detail in Chapter 5. If he can not get his nose around and point it at you, you are inside the Turn Circle. You must watch your opponent and compensate for his maneuvers. Based on the jetfighters modeled today in simulations, 2nm is a decent rule of thumb for range to the bandit for estimating basic Turn Circle.
GOING OFFENSIVE
The entire reason we are doing this is to get the bandit into your "Kill Zone" and end the fight as fast as possible. The longer the fight goes on, the better the odds are that the bandit will get into a position to take a shot at you.
CRASH’S RULE NUMBER 1: If you have a shot take it NOW! Do not wait for a better chance, or until you can get close enough to use guns instead of missiles. To die with a full wing of missiles because you thought, "I might need them later in the mission" is, well ... it is just "plane" silly.
As you approach the rear of a bandit, you have a very short period of time before his Defensive BFM will put your missiles out of parameters. As soon as you have a shot, TAKE IT! The harder the defending target turns, the less time you will have before you are forced into a decision on your next move ... and then it may be too late.
So, your missile shot has missed (or you missed the chance before the bandit saw you). You pull into an attacking rear aspect position. The bandit sees you and starts Defensive BFM ... your move. At this point, you are committing the next stage of the fight to guns (or a rear quarter HEATER shot if you're lucky). When do you start your turn to maintain your advantage – to "Stay in Control" of the fight? The point you want to begin your turn will be approximately the same place the bandit started his: this is known as the "Entry Window". This window will be to the inside of the bandits turn circle (remember you do not want to start an Offensive BFM maneuver outside of the bandits turn circle). Figure 3-5 shows the Entry Window. Once you enter the window, begin your high G pull into the bandit.
Figure 3-5
Other ways to estimate the Entry Window would be Chaff and Flare possibly dropped by the bandit as he started his turn, or when the bandit is about 30°off of your nose. Or maybe a bit of debris from your near miss missile shot. Watch for any signs that may help you, but do not focus on where you should turn at the expense of not paying attention to what the bandit is doing.
Next consideration as you approach the Entry Window is Corner Velocity. You want to be at Corner Velocity. If you enter too fast or too slow, you will be forced into a Lag Pursuit where you will probably not be able to pull your nose into Lead Pursuit for a gun shot. You must be at your best turn rate, which is Corner Velocity, to have the control and the option to pull your nose around fast enough to take a shot when you want to.
O’kay, are you still with me? You have determined the Entry Window, and you have gotten to it at Corner Velocity ... everything is going great so far. Now you want to pull your high G turn into the bandit. The idea now is to keep in Lag Pursuit (by choice) until you have pulled into guns range, somewhere between 2,000 and 3,000 feet. If you find yourself creeping up on Pure Pursuit, back off the stick a little and maintain Lag Pursuit ... and watch your speed during this period so you do not bleed off or pick up too much speed so you keep at Corner Velocity.
Once you are in guns range, you must maintain your overtake speed with the throttle. When you take the guns shot, you want to be as close to the same speed as possible. As soon as you go to Lead or Pure Pursuit, the throttle is the key to not over shooting the bandit. You will work the throttle back and forth a lot during this time.
(A friend asked me just the other day why all the texture is worn off my TQS throttle in the palm area ... I mean this baby shines. I like to fly in close BFM and usually close to the ground as well which adds a whole new dimension to the arena). You may have the throttle from full idle to full burner during this section and everywhere else in between. You may even need to pull "out of plane", into a High or Low Yo-Yo type maneuver, to keep your position. (These maneuvers will be described in detail in Chapter 8: ACM). Figure 3-6 shows a High Yo-Yo maneuver. In the case in this picture, the F-16 is using a High Yo-Yo to bleed speed to keep behind the F-15.
Figure 3-6
You’ve worked it, you’ve jockyed, you have gotten yourself lined up to take a guns shot. There are 3 things that you must now do to get a successful shot.
1. Be in range. Rear (Low) Aspect shots should be taken no more than 2500 to 3000 feet away. Front (High) Aspect shots may be as far as 4000 feet out.
2. You must be in Lead Pursuit when you pull the trigger. Bullets are unguided projectiles. Most gun shots TOF (Time of Flight) is .5 to 1.5 seconds. You must compensate for this by pulling a Lead Pursuit. This is not STAR WARS, these aren’t lasers ... they will not fly straight. If you put your nose on the bandit, your shots will pass behind him. Note that the closer you are, the less pronounced the Lead Pursuit will be.
3. You must be in the same plane of motion as the target. Before anyone tells me you can pull a little high and have your bullets drop due to gravity; If this works, you are taking your shot way too far away (and if you consistently hit like this, you have one heck of an eye!). Lets just make it simple: Be in the same plane of motion when you take your shot.
There is one more thing that is critical for survival during this phase. Think about what you are going to do if you carve off a piece of his wing, tail, etc., and it comes flipping towards your plane (actually, you will be hurtling yourself towards it much faster). If you get too close, this could kill you (most new sims are modeling this now. It has changed the way many computer jocks fly and makes real BFM that much more important).
LINING UP YOUR SHOT
How do I know when my target is in my sights? This is going to change from sim to sim and from plane to plane. These days, most sims come with a pretty good section on how to line up your target in the modeled gunsight. I could do a few lessons just on this, so I will defer this to the individual manuals. I will however give you a look at a few variations of gunsights in current sims.
The Gun Snake from the EF2000 family of sims by DiD. The bullets will follow the line, "snake" to impact at the circled end of the snake. The circle on the end will creep around to the right as you close in range.
CF-18 photo © Neville Dawson
The gun pipper in GSC’s F/A-18 HORENT KOREA. Similar in idea to the gun snake in EF2000, but without the snake. The circle will count down range. Also, this one will give you a shoot designation when you are in parameters (and is pretty accurate too.).
SSI’s SU-27 and the tried and true Gun Funnel. Basically, if the funnel's lines both touch a wing, you should hit the target (very basic and simplistic explanation). For anyone looking for a sim to practice your "close in" combat skills, this is a really good choice. Never mind the graphics, it does everything else very well.
Sukhoi Su-37 © Neville Dawson
For equal time, since we shot down an F-15 in SU-27, here is the gun funnel depicted in JANES latest release, F-15E. This is probably one of the smoothest working funnels I have seen. This includes little range markers as well.
One of the several gun sighting modes in MicroProse’s FALCON 4. Works sort of like a gun snake, sort of like a pipper. Not my favorite choice in sights, but I wanted to show you this one. FALCON 4 has a few other sight options including the gun funnel.
This material is copyrighted and may not be reprinted in any form without permission of the publisher.
Last Updated November 20th, 1998This article was originally published at the Combat Simulations site
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