An Introduction to Simulation BFM, Part
The following articles were written
several years ago in support of a web site devoted to Janes
ATF, and later, Fighters Anthology (FA). Much of the material
is of a general nature and may be applicable to all sims.
Newcomers to air combat simulation may find this material
helpful in understanding some of the terminology of air combat.
For those of you interested in the
technique of learning and flying BFM while using the player-to-target
external view can find some tips here. The FA sim has several
features that make it a good choice for practicing BFM with
the external view. In particular, you may find the explanations
of how to fly a variety of specific maneuvers to be helpful.
There are no illustrations to these
articles, however, many of the techniques are covered in the
Its All A Matter Of Perspective series of
BFM Lesson 4 - BFM Concepts
Well, we finally got airborne!! Here
we are, ready to go...but before we jump right into a double
underhanded wifferdill or whatever, let's talk a bit about
how to fly this sim. Now, for you experienced guys (and gals!!),
please hang with me here...just maybe there might be something
here for you as well as the beginner.
First of all, let's remember that
we're flying a flight sim, not a real jet. As good as
ATF as modified by Greg is (and it's real good, much better
than the game right out of the box), it still ain't the real
McCoy...and probably will never be, given the limitations
of the program. For example, here are some sim flight characteristics
which differ from real life and which tend to reduce BFM effectiveness:
1. ATF aircraft accelerate the
same at one G as they do at less than one G. This essentially eliminates the Low Yo-Yo as a effective BFM
maneuver. In real life, reducing the G load to less than one...normally
to about one half G...results in a significant reduction in
drag and a corresponding improvement in acceleration. ATF,
as presently programmed, doesn't do this.
aircraft roll under high G...meaning high angle of attack
(AOA)...the same as they do at one G. This is
also unlike the real world. Real fighters tend to roll considerably
slower when at high AOA, and in doing so, they tend to lose
energy very quickly. In real BFM, this can be used to your
advantage if used to force an attacking opponent to overshoot.
ATF doesn't fly like this, and as a result, the BFM maneuver
known as a Vector Roll or a High G Rudder Roll is not possible.
These maneuvers are used to control closure or overtake and
are do not produce the same effect in ATF as they do in real
life. The latest sims such as F-15 and Falcon 4 do a much
better job at modeling high AOA maneuvers.
3. In the
real world, the effect of gravity on an aircraft's ability
to turn is a very important part of BFM. Gravity is
often referred to as "God's G." Gravity always
produces a force of one G on your jet, and how you use that
one G can be significant when it comes to turn rate and radius.
I don't want to get into the serious math at this point...if
you just have to know, please e-mail me<g>...but what
it boils down to is this: if your lift vector is anywhere
above the horizon, then God's G is working against you and
you have less G working for you than you think...up to one
G less. Orient your lift vector below the horizon...as in
being upside down...and God's G now improves your ability
to turn by adding up to one G to your total G load. This
effect is responsible for maneuvers being flown in the vertical
as well as the horizontal planes, and is often the singular
evidence of BFM proficiency in a pilot. From what I have seen,
most flight sims don't model this as well as they should.
Turn rates and radii appear to be the same regardless of lift
vector orientation. If this is the case...and it seems that
way to me...then sim pilots have lost an important tool in
their BFM bag of tricks.
But, not to worry!! We can still do
a pretty credible job of simulating BFM and have a great time
doing it. In talking about how to fly our BFM maneuvers, we
need to stress again our basic objective: we want to maneuver
our aircraft behind our opponent to a position where we are
co-speed and at very little to zero angle off, and in gun
range. This is classic BFM...it hasn't changed from World
War One to the present. There are many other maneuver objectives
in the total air-to-air combat environment, but we are only
going to concentrate on the most basic. You will learn how
to reduce an angle off and aspect problem in order to close
in to a gun kill position.
A word of caution. In the world of
air-to-air, there are few absolutes. Other than "what
goes up must come down," there is little that somebody
somewhere can't take issue with if they want. Fighter pilots
come equipped with over-sized egos and tend to operate from
the point of view that whom ever yells the loudest, wins.
What I'm going to say about BFM is only my point of view,
and it's meant to provide beginner level instruction in the
fine art of going about gunning somebody else's brains out.
As always, there are other ways to skin this cat. Take advantage
of all the sources of BFM info to get as wide a point of view
Let's now define some basic definitions
and objectives that will apply to our discussions of specific
maneuvers. This terminology is critical. Please understand
the following completely.
Control. You can have too much of a good thing!! For
our maneuvers, try to maintain airspeeds in the 350-450 knot
area...this is the corner velocity (CV) speed range
for most of the ATF fighters. CV is the airspeed that will
allow you to pull maximum G at the lowest speed and thus gives
you your quickest, tightest turn. The caret symbol on
your ATF HUD airspeed scale shows you CV for your chosen jet.
Your maneuvering may take you above or below the CV range
for periods of time, but as a rule, that speed range is a
good place to start.
Airspeed is what you see on your HUD...closure is the rate
at which you are accelerating or deccelerating from your opponent. Closure is what BFM is concerned with...not airspeed.
BFM maneuvers control closure, not airspeed. You don't care
how fast your opponent is going, you only care about whether
or not you are catching him!!
of Reference. THIS IS ABSOLUTELY CRITICAL. There
are two frames of reference in BFM...the horizon and your
opponent's plane of motion. Depending upon the maneuver,
you will use one or the other or both. In general, your opponent
is of more importance than the horizon.
Your Frames of Reference. The horizon line in your
HUD and the Other View window help keep you oriented to
where the horizon is if it is out of view...normally, this
is not a problem. But what do we mean by your opponent's
plane of motion? What are the visual clues for this? Here's simple rule of thumb. His plane of motion is where
his lift vector is pointed. Under positive G, his lift vector
comes out of the top of his aircraft...if he has a single
vertical stabilizer (rudder), then you can use it to represent
his lift vector. If he is bunting (negative G), then his
lift vector is coming out of the bottom of his aircraft.
This lift vector defines his direction of turn. Imagine
his wings as representing a flat plane. His lift vector
is perpendicular to this flat plane. If you match his angle
of bank, your lift vector is aligned with his...you are
by definition in or parallel to his plane of motion. Now,
here's the goodie. If you can see the top of his wing and
you are in his plane of motion, you are INSIDE his
turn...if you are looking at the bottom of his wing, most
likely you are OUTSIDE of his turn. In BFM, we
usually want to be inside of our opponent's turn...therefore,
you must be looking at the TOP of his wing. Inside his turn
means closure...this is lead pursuit. Outside his turn generally
means no closure...this is lag pursuit. Most of the time,
you will be in lead pursuit
b. Relative Energy States.
You can use the horizon and your opponent to help control
your energy. If your opponent is in a turn, his low wing
represents the direction of positive energy for you relative
to him. If you are trying to close on him, fly on his low
wing side. His high wing represents a minus energy area...if
you have too much energy relative to him, fly to his high
wing side. In most of our maneuvering, we will be flying
on the low side as we try to gain or maintain relative closure. Low wing + Top of the wing = closure = lead pursuit.
High wing + Bottom of the wing = no closure = lag pursuit. Folks, it doesn't get any simpler than this.
to the Elbow...Pulling to High Six. You may have heard
these terms before. They are immortal. They are timeless.
They are Omnipotent. They are the be all and end all of basic
BFM. Control of the elbow is control of your opponent. Control
of high six is victory. He who is at high six is behind. He
who is not is, therefore, in front. He who is in front, dies.
Elbow. Look at your arm. Your hand represents your
opponent. Your elbow is where you want to be. It is where
you want to point your lift vector at. It is where you want
to end up...behind your opponent.
b. High Six. That area behind and above your opponent...relative to
THE HORIZON. The "six" refers to the position
relative to him, ie, the area behind him. "High"
is in reference to where the horizon is. If you can fly
to the "high" side of your opponent, you are pushing
him out in front. You must understand this concept. It is perhaps the most basic of all BFM. Lift vector control
is often the contest for who controls the high six of their
opponent. Know this cold.
Whew!! Enough of this rocket science!!
This info is the foundation for understanding BFM. These terms
will be the language of all follow on discussions. Please
read this article until you have it down pat. If you don't
understand something, please write me.
BFM Lesson 5 - More Concepts
Well, it's time to get our hands dirty...do
a little flying...and look at some of this BFM stuff we have
been discussing. Let's start out with some general ideas that
apply pretty much across the board to all maneuvers. And once
again, let's review the ground rules...this discussion is
aimed at a guns only, one v one, beginner level look at basic
BFM maneuvers designed to reduce angle off and aspect angle
to produce a low angle off gun kill.
Management. Earlier we talked about corner velocity
(CV)... we said CV was about 350-450 knots for most of the
aircraft in ATF, and we said that we wanted to stay in this
speed range for most of our maneuvering. If your choice of
aircraft has an afterburner (AB), use it for two purposes
only: for acceleration to a desired speed, and to maintain
your present speed while in a high G, energy bleeding turn. Do not fly around in AB...you will burn too much fuel
and you will not stay in the CV range. Remember, your turn
rate and turn radius are a direct function of your airspeed...too
much speed and your turn performance suffers.
use while flying in the vertical. Any time you are
not flying level with the horizon, you are to some extent
flying with a component of your flight path in the vertical...in
doing so God's G may be helping or hurting your turn performance.
As a general rule, when your lift vector is pointed in the
"up" direction relative to the horizon( the bottom
half of a loop), do not use AB. AB in this case tends to
increase your turn radius, slow your turn rate, and increase
your altitude lost. But do use your AB when you are flying
with your lift vector pointed "down" (the top
half of a loop)...here AB will help you maintain your energy
and God's G will add to your turning ability. So...when
you are "right side up," i.e. pulling out of a
dive, don't use the AB. When you are "upside down",
i.e. on your back, do use AB. Remember, this is just
general advice. If you don't need AB in a given situation,
don't use it!!
Turns. The ability to lead turn your opponent is the
Holy Grail of BFM. Without a doubt, it is the number one key
to success in you winning your BFM contest with your opponent.
If you lead turn him, he cannot, by definition, lead turn
you. If Moses had been a fighter pilot, he would have said
"Do unto others before they do unto you," meaning
lead turn the other sucker before he can do the same to you.
But what is this lead turn thing, how do you do it, and what
does it look like?
it is. A lead turn is a maneuver which you initiate
to reduce angle off before your flight path crosses your
opponent's flight path. It used to be called an "early
turn" because you start the turn before he starts his.
The simplest example of a lead turn in to visualize two
aircraft approaching each other head on. If they wait until
they pass each other before they begin a turn towards each
other, they will roll out essentially facing each other
again, i.e. no advantage gained by either. But if one aircraft
begins to turn before they pass each other, he will complete
his turn and be pointing at his opponent before that aircraft
has completed its turn...advantage goes to the pilot who
turned first. Another example...visualize two aircraft weaving
back and forth criss-crossing their flight paths...if each
aircraft waits until he crosses the other's flight path
before he reverses his turn, no advantage will be gained
for either. But if one pilot begins his reversal slightly
before the flight paths cross, he will "gain angles"
on the other pilot, meaning his angle off will be reduced.
Try this with your hands...make a weaving motion with your
hands...before they cross each other, make one hand start
to turn back the other way. Notice how that hand seems to
slide behind the other hand? The same thing will happen
in an airplane. In either case, one pilot began his turn
before the other pilot with the end result being an advantage.
do you do it? The concept is pretty simple...it's
the execution that is the hard part. Like in most things,
you can get too much of a good thing. In this case, this
means it is possible to begin your lead turn too soon by
being too aggressive. This usually ends up with you flying
out in front of your opponent, and in general terms, this
is considered poor form<g>. For head on pass type
situations, I would recommend, as a rule, that you wait
until your opponent passes your 10:30 or 1:30 position,
or about 45 degrees off your nose, before you begin your
turn. If you are scissoring (in a weave...criss-crossing),
I would advise waiting until you have covered at least 1
/ 2 to 2 / 3 the distance back towards your opponent before
you reverse the turn. These are just yardsticks, and pretty
conservative ones at that...with experience, you may choose
to be more aggressive.
does it look like? Use the F7 exterior view to help
you visualize the lead turn...particularly in a scissors
maneuver, since your opponent is otherwise out of view.
I SAY AGAIN...use the F7 exterior view to "see"
the need for and the execution of the lead turn...particularly
in those close in situations where your opponent is not
in sight if you are in F1 forward view. Once I'm in close
quarters with my opponent,I tend to fly the entire fight
in F7 until I'm ready to shoot. I use the Other View window
to tell me when my opponent can be seen in F1...if you can
see him in the little Other View window, he will be visible
in F1. F7 allows an intuitive sense to BFM that F1 cannot
give you. It clearly allows you to see you angular relationship
to your opponent and it gives you a rate of closure that
is so necessary when timing a lead turn. F1 will not do
this for you. But there is a serious problem in using F7...you
must keep yourself oriented with which way to turn. It is
very easy to turn the wrong way. Those of you who have flown
radio controlled aircraft will understand exactly what I'm
talking about. My technique is to constantly talk to myself
about what I want to do while I'm maneuvering. I look at
the F7 screen and say to myself..."right turn"
or "left turn," otherwise I get all screwed up<vbg>.
But once you get the hang of it, you'll find F7 allows you
to feel a sense of "flying" BFM that no other
view will give you. It's as close to the actual thing as
the sim environment is going to give you.
OK!! This has been a bunch to digest...please
feel comfortable with these ideas. If you aren't, then add
your question to the SimHQ Air Combat board (I guarantee some
one else has the same question but is too shy to ask.). Remember,
there are no dumb questions, only dumb answers! I promise
not to give too many dumb answers...you do your part by speaking
up if you don't understand. If you want a private answer,
then e-mail me.
One other thing. I'm an airline pilot
these days, and as a result, I'm gone for days at a time.
If I don't get right back with an answer, that's why. But
I will answer, trust me.
Next up is the High Yo-Yo or Quarter
Plane maneuver. We'll look at how to deal with a bandit that
is turning hard into us and is creating an angle off / aspect
angle problem as a result.
BFM Lesson 6 - Flying The Maneuver
This is the first discussion of how
to actually fly a BFM maneuver using the ATF flight sim as
modified by Greg Pierson. Please refer to the earlier article
on how to set up your screen if there are any questions about
basic keyboard / flight stick techniques.
This article will talk about how to
handle a situation where your opponent is turning hard enough
to cause him to fly out of view...usually this happens due
to two reasons...either you had too much airspeed and you
literally flew past him, or, more likely, he turned hard enough
to cause a flight path overshoot due to excessive crossing
angles. We'll talk about both situations...too much airspeed
or too much crossing angle. In either case, regardless of
flight sim, the most typical response is to turn in the last
known direction of your opponent and attempt to chase him
with him out of view. This is kinda hard to do...even the
Red Baron couldn't fly blind!! There is a better way...and
that is the technique of shifting between forward view (F1)
and an exterior view (F7) to keep the bandit in sight. Please
note there are other exterior views...F9 and F10...which also
show you a big picture view of you and your opponent, but
I do not recommend using either to practice BFM with.
Started. Once you have set yourself up behind your
opponent as previously described in the set up article, begin
by adding power to close on your opponent. ATF will begin
maneuvering him around and your job is to stay behind. At
some point you will find that you cannot keep him in sight
no matter how hard you try to turn...what do we do?
BFM Textbook Answer. Various BFM texts will describe
a number of maneuvers for this type of situation...high yo-yo,
quarter plane, barrel roll, vector roll, etc. Each of these
maneuvers is designed to address a specific BFM problem...either
too much closure, or too much fuselage misalignment (angle
off / aspect angle).
Yo-Yo. Traditional BFM academics use the high yo-yo
as a maneuver designed to control closure. The high yo-yo
is used to slow your rate of closure on your opponent. This
does not necessarily mean that the maneuver slows you down,
i.e. you lose airspeed (although this often happens as a
by product)...instead, the maneuver slows you down relative
to your opponent by lengthening your flight path relative
to your opponent. It is true that the high yo-yo also tends
to reduce aspect and angle off when flown properly, but
this is a secondary result of a maneuver intended to solve
a closure problem. Yo-yo can be big or little, depending
on the magnitude of your closure problem.
Plane. The quarter plane is a last ditch maneuver
intended to keep you behind your opponent. It is designed
to keep you behind your opponent's 3 / 9 line and sacrifices
angle off and closure in the process. It is essentially
a reposition maneuver and almost always requires a follow
up maneuver such as a low yo-yo to re-enter the fight. Consider
it an "emergency procedure"!!
Roll. The barrel roll is designed to solve an aspect
problem. Use this maneuver when you can match the turn rate
of you opponent but you find yourself too much inside his
turn. In this situation, you have aligned your fuselage
with his but you have too much lateral separation, i.e.
you have too much sideways displacement. Your objective
is to reduce the lateral separation without losing your
angle off advantage...meaning you want to get behind him
and still keep your fuselage aligned with his. In this situation,
you do not have a significant closure advantage.
Roll. The vector roll is a specialized adaptation
of the barrel roll. The vector roll is designed to handle
too much closure and is used when your fuselages are close
in alignment. The vector roll is an aggressively flown barrel
roll where high G is used to roll around your opponent's
flight path. The resulting longer flight path which you
fly slows you down relative to your opponent.
the Maneuvers. Let's talk about how to fly each of
these maneuvers using the F1 and F7 views. Please keep in
mind my original "yeah, but"...this is only one
way to describe BFM relative to the flight sim...there are
other, and maybe better ways, but, for right now, this is
going to be my way (g). We'll talk about each maneuver by
describing how to recognize when the maneuver is necessary
(see the need) and how to perform the subsequent corrective
action (stick and throttle response).
a. High Yo-Yo.
See the Need. You are turning with your opponent.
He is getting larger in your F1 view (high closure) and
he is moving toward the side of your screen. There is
at least 45 degrees of difference between his heading
and yours (high angle off). You are unable to keep him
in view by continuing to turn.
Response. While still in F1, roll toward your opponent
(away from direction of turn) until your nose points just
behind him. Your angle of bank should be approximately
90 degrees less than his. Begin a moderately hard (4 G)
pull away from his flight path. Go full power. Switch
to F7. You will see your aircraft climbing "above"
your opponent and there will be a significant mismatch
in fuselage alignment. Hold this position (do not continue
to pull or roll) until you see your opponent start to
increase his separation from you. This will only take
a second or two. Immediately roll back towards your opponent.
Aim your lift vector (visualize this as your rudder or
as an arrow coming out of the top of your canopy) in front
of your opponent. Now pull hard back "down"
towards your opponent until your aircraft looks like it
is pointing in his direction. Now look at your Other View
window. Is he in the window field of view? If so, switch
back to F1 and press your attack. If not, re-examine your
nose position relative to the other aircraft. Where is
it pointing? Roll and pull to point your nose at your
opponent. Can you see him now in the Other View window?
If you can, stay at full power for a moment or two as
you "descend" towards your opponent...then reduce
your throttle, go back to F1 and blow him away!
Sidenotes. The yo-yo is best started early so that
you don't have to fly a big one. Several little ones are
easier to handle than one big one. Expect to have to repeat
the process as the bandit maneuvers...the sim AI will
attempt to oppose your maneuvering...just like a real
opponent would. When in F7, avoid turning in the wrong
direction by talking to yourself about which way you want
to go, i.e., "turn left...relax G"..."turn
right...pull." Remember, you position yourself by
aiming your lift vector with roll, and then you move your
nose with back stick (G). Practice and repetition will
make this F1 / F7 / F1 process seem natural as you get
familiar with the concept.
b. Quarter Plane.
See the Need. As before, you are turning trying
to keep your opponent in view, but he has really put a
hard turn on you and there is no way you can match his
turn. Not only that but you are too close...he's huge
and you're about out of ideas!! What should you do? It's
time to get out of Dodge!! You have to do two things...get
out of his plane of turn, and stay behind him. The quarter
plane is like an extreme high yo-yo. The "quarter"
refers to your resultant flight path where you orient
your lift vector 90 degrees away from his plane of turn
(90 degrees being one quarter of 360 degrees) prior to
Response. Immediately roll to aim your lift vector
AT LEAST 90 degrees away from your opponent. Pull hard
into the vertical. Switch to F7. Go full AB. Now analyze
your position...are you separating away from him while
at the same time staying behind him? You must stay behind
his 3 / 9 line. If this is not the case, then roll your
lift vector to point behind him and pull to move your
nose further to his 6 o'clock. Put your flaps down if
required (I like to put mine down...the sim is more maneuverable
with flaps down). Now roll back to aim your lift vector
at your opponent. Are you now behind him? If so, then
pull back towards him and re-enter the fight. Stay in
AB to get your speed back...raise your flaps to help accelerate.
Sidenotes. Think of this maneuver as a zoom emergency
procedure, because that is what it is. It ain't pretty...it's
supposed to save your butt and preserve your offensive
position. The whole point is to keep behind his 3 / 9
line...you do that by using F7 to pull towards his 6 o'clock.
Watch out for a stall. Use full AB and flaps. Don't be
gentle. Roll fast...pull hard to stay behind him.
Roll / Vector Roll. I'll describe these two maneuvers
together since they are pretty similar in execution (G being
the major variable). Don't expect to use these much in ATF...they
are well up the "food chain" in sophistication
See the Need. In F1, your opponent is turning and
you are turning with him. Your angle off is low...fuselages
nearly aligned. Your aspect, however, is too far inside
his turn...meaning that you are too far away from him...too
much lateral displacement. What you want to do is to somehow
move your jet across the space between you and your opponent
without changing your low angle off.
Response. While in F1, add back pressure as required
to match his fuselage. Then switch to F7 and begin a moderate
pull up. After raising your nose about 10-20 degrees,
start a slow roll into your opponent while maintaining
a little back pressure. You will start to fly across the
space between the two aircraft. Relax your back pressure
to stop your nose from turning any further. As your aircraft
nears the turn radius of your opponent, roll your aircraft
to point your lift vector into the plane of his turn...match
his bank angle. Then add back pressure to pull your nose
back into alignment with his fuselage. You should now
be behind him and above the plane of his turn. Point at
him, check your Other View window, and when he is in sight,
switch to F1 and continue the attack. For closer initial
ranges and higher closure rates, the maneuver should be
flown much more aggressively. You will end up rolling
around your opponent's flight path...your resultant longer
flight path relative to him will reduce your excessive
closure while reducing your aspect.
Well, that's enough to digest for
now!! Give this a try. Remember, it's the "big picture"
view of F7 that makes all of this possible. Using F7, you
will, with practice, intuitively "see" the need
for a flight path correction much in the same manner as an
actual pilot would in a real BFM environment.
here to go to top of this page.