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Air Combat 3
How to Live and Die in the Virtual Sky
by Dan "Crash" Crenshaw, www.deltahawks.org
CHAPTER 3:
OFFENSIVE BFM
This is the lesson that most of you really want and think will give you the edge. I should have made this the last lesson to keep you from stopping your training here … too early. But, in order to understand the defensive maneuvers that we will discuss next lesson, you need to know what the offensive maneuvers look like first.
Offensive BFM is, in a nutshell, what you need to do to kill your opponent. You need to keep your maneuvers smooth and graceful. Sudden jerks, quick directional changes, and basic rough handling of the aircraft will cause loss of energy, speed and attitude (both of the aircraft and your mental attitude when all your fancy moves makes you a wallowing, low speed pig, ripe for the kill by your opponent).
The basic objective of Offensive BFM is to put you in control of the fight, and in position for the killing shot. If your opponent has no idea that you are there and maintains a straight and level flight path, no BFM is needed. You just drive up behind the bandit and shoot him. Offensive BFM is needed when the bandit is aware of you as a threat and attempts to maneuver away from you.
Once your opponent has begun Defensive BFM maneuvers, you need to employ Offensive BFM maneuvers. To maintain control of the encounter, you must maintain a position in the "6 o’clock" area of the bandit. This is the position where you will get the most effective, likely and controlled shot. This is also known as "flying to the elbow".
Figure 3-1
Figure 3-1 shows two different scenarios of not using Offensive BFM once a bandit starts to break. If you do nothing, you will drive straight ahead, lose the Angle advantage and will most likely put you at the disadvantage in a hurry. If you turn immediately with the bandit, you will probably end up in front of the bandit and at an obvious disadvantage.
What we need here is a hybrid of these two maneuvers to resolve the Angle Problem created by the bandit’s turn. We need to decide how and when to turn based on what the bandit is doing.
Turns
One of the most encompassing and important parts of BFM, of any type, is the turn. To be able to develop competency and skill in BFM, you must understand some basic concepts of turns. We will discuss positional energy, turn radius and rate, corner velocity, and turns in the vertical.
Energy:
There are two types of energy in air combat maneuvering: kinetic and potential. Kinetic energy is directly related to the speed or velocity that the aircraft is traveling. Potential energy is "stored" energy available for use. This does not mean stored like in batteries. Potential energy is directly proportional to the altitude of the aircraft. At high altitude, the aircraft has a HIGH potential energy, while at low altitude, the potential energy is LOW.
The easiest way to explain this is to visualize a jet at 30,000 feet. This pilot has the option to put the jet into a dive, thus increasing his airspeed. The higher he is flying, the more speed he can generate in a dive. An aircraft at low altitude of 5,000 feet has much less room to increase speed in a dive.
Always remember: you can trade altitude (potential energy) for speed. Likewise you can trade speed for potential energy. If you have one, you have the ability to have the other when you want or need it.
You can also trade energy for nose position. As I mentioned in lesson one, maneuvering costs energy, and any "dancing" you do will cause your aircraft to slow down and lose energy. The higher the G pull in a maneuver, the more "costly" to your energy level it is. The only consolation to this is that the bandit is working under the same laws of physics and has the same problems to overcome.
Turn Radius and Rate:
Turn radius and rate are the two primary characteristics of turns. Radius is just the "tightness" of the turn circle. If you were to look down from a Gods Eye View (see Figure 3-2), the radius is the distance from the center of the turn to the turn circle, or plane, of your aircraft in feet. While the actual math for calculation of turn radius is not important (TR=V2/gG where TR is Turn Radius, V2 is Velocity squared, g is gravity and G is G force. Got that?), it is critical to understand that Turn Radius increases exponentially with velocity, or speed. A 500 knot turn at 9 G’s will not be twice the size of a 250 knot turn at 9 G’s, but roughly 4 times the size. Just remember that airspeed has a much greater effect on turn radius than does G force effect.
Figure 3-2
Turn Rate is how fast your aircraft can get around the Turn Radius. It also indicates the speed of which you can change the nose position of the aircraft. Turn rate is dependant upon G’s and Velocity (Turn rate = KG/V, where K is a constant and G and V are the same as in the turn radius calculation. The constant is based upon several factors including altitude, humidity, temperature etc.). Turn rate is measured in degrees per second.
To really over simplify this, if the velocity remains constant the higher the G’s the faster the turn rate. And inversely, if the G’s remains at a constant, the lower the velocity, the faster the turn rate.
CORNER VELOCITY:
Corner Velocity is the airspeed at which your aircraft has the fastest turn rate and tightest Turn Radius. This is not the slowest you can fly while pulling back on the stick as hard as you can. You can not pull higher G’s at slower speeds. Less lift is available, therefore there is less force available to work with.
Also, at high air speeds, you are unable to pull high G’s. So somewhere in between really fast and really slow is your Corner Velocity. In most modern jet fighters simulated, this is between 400 to 500 KCAS (knots, computer airspeed). There are exceptions of course: EF2000 has a corner velocity of about 350 KCAS. If there is no documented speed in the manual, you will need to play with the handling to figure it out. It also needs to be noted that altitude can affect this figure as well.
There are 4 basic means by which you can adjust your airspeed, up or down, to reach Corner Velocity.
Throttle position:
Pretty simply here, more throttle to increase your speed, less throttle to slow down.
Drag Devices:
So you are going too fast and chopping the throttle won’t slow you down fast enough to get to Corner Velocity as soon as you need to. Your main device here is your speed brake. You can also use flaps and as a last resort (not recommended), you could use your landing gear. Be careful with this last one. Many simulations are modeling gear damage due to lowering at excessive speed. You may end up with your gear in a permanently down and damaged position, making maneuvering, and ultimately landing, rather difficult.
Nose Position:
Nose Position refers to the nose of your aircraft in relationship to the ground. Point down and you can increase your speed, point up, and you bleed off speed.
Aircraft G’s:
The higher G force you exert on the aircraft, the faster you will bleed off energy (speed).
These methods can be used singularly or combined, depending on how much speed you need to increase or decrease. I have often found myself with a chopped throttle, speed brakes out, pulling into a high G slow banking climb in an effort to slow down in a hurry.
Point to remember: your first turn is the most important turn in the fight. Blow it and allow the bandit on your 6, the fight could end very fast and with an outcome you would rather not talk about. Use all your tools to achieve corner velocity, and you could be on the bandits 6, in control of the fight, and in a very good position to add a tally to your kill sheet.
"Rate Kills" is a common fighter saying. Simply put, a fighter with a higher turn rate can out maneuver a fighter with a tighter Turn Radius. The ability to put your nose on the bandit to allow a shot is more important that being able to fly in a tighter circle. Get to your Corner Velocity, pull your nose on him, shoot him … the party is over, you win. You no longer have to worry about him.
VERTICAL TURNS:
There are two key factors for you to consider in a dogfight; the bandit and the ground. Both can kill you. However, the ground can also help you. The gravitational pull of the earth can actually allow you to pull a faster turn rate and tighter Turn Radius than a turn that has you parallel to the ground.
The earth’s gravitational pull causes the actual G force to be different from the G meter reading in your HUD. This is also known as Cockpit G OR "Gods G". The actual G force affecting the fighter is known as "Radial" G’s. Figure 3-3 shows an example of Radial G force vs. Cockpit G force.
Figure 3-3
At point A, the fighter begins a high G vertical turn. The HUD is reading 5 G’s. At point B, in the pure vertical, the HUD and actual G force are the same. HUD G registry is the actual G force applied if you are in a full vertical climb or dive. Gravity has no affect on Cockpit G in this position.
At this point, your Lift Vector is parallel with the ground. The less parallel the Lift Vector is with the ground, the more effect G force will have on your maneuver, up to a maximum of 1 G. If the Lift Vector is pointing up, you would subtract the G force from your HUD reading. If the Lift vector is pointing towards the ground, you would add to the G force registered. Radial G is merely the effect of gravity on cockpit G. At Point C, completely inverted, the HUD reads 5 G’s, but Radial G’s are actually 6 G’s. As the jet continues down the backside of the vertical turn, at point D, the G force and actual G force is identical again at 5 G’s.
Radial G describes the effect of the gravitational pull of the earth on the aircraft, which could be positive or negative, depending on the attitude, position and maneuver of the aircraft. Radial G is also the determining force for Turn Rate. Each Radial G could be worth up to 4° of Turn Rate per second!
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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