[ Need sections on energy, turn rate vs radius ]

DRAFT Flight School Aerobatic Training

You may wonder why you would need to learn aerobatics for air combat. My answer to that would be one word; control. You must learn to control your plane at the limits of its performance and not go beyond. You must be able to optimize the best characteristics of your plane while preying upon the worst of your enemy's.

In this section we begin to look at the various characteristics you will be interested in learning. We look at how altitude and airspeed affect performance and we will explore the limits of some of these characteristics.

Stalls and Spins

The first thing we will look at is stalls and spins, how you get there, what happens when you do and what do you do when it happens.

Remember from the discussion of the Four Forces [ ref ] that a stall occurs when the angle of attack exceeds the maximum for producing lift. Stalls can occur at any speed, not just when the aircraft is slow. A stall at high speed is referred to as an accelerated stall [ glossary? ].

The only way to recover from a stall is to reduce the angle of attack. The stick controls your angle of attack so the only way to do that is to push the stick forward. Remember this when you are 500' up and have stalled or begun to spin! There's no way in the world that you are going to recover unless you push the stick forward.

Practice

We're going to practice stalls now so you can see how they affect different planes in different ways. You will do at least 3 stalls and recoveries in a plane of your choice.
  1. Enter your first stall, by levelling at 5000 feet. Throttle back to lose airspeed and maintain level flight. As you get close to 150 kts, drop your flaps and continue to maintain level flight. The stall light will start to blink indicating you are close to stall and will eventually stay on with the stall warning buzzer blaring. To recover, go full throttle, flaps up and push the stick forward enough to break the stall. This may be nothing more than relaxing the back pressure on the stick, so don't just bang it all the way forward.

    If you do not get the flaps up quick enough, you may experience the nose tuck described in the Solo Flight sections [ ref ].

    Do this several times. You may wish to remain in a stalled state by continuing to pull back on the stick a small amount and observe the instruments for a short time. Notice that you will begin to descend very rapidly while your airspeed is very low. As you recover, your airspeed may jump up quite high. This has been used to an advantage by some players and is not quite realistic, but that's the way it is. A zipped example film showing how not to recover from a stall and the speed jump is available for your review.

  2. Your second stall is a full power stall. Starting again at 5000', make sure your flaps are up and slowly raise the nose to bleed your airspeed. You may want to wait to throttle up until your speed drops to 150 kts so you don't end up climbing a long ways while waiting for you speed to drop. Again you will stall, but you have no power to add, so the only way to recover is to reduce your angle of attack by pushing the nose down. Again, you may want to remain in a stalled state for a short time to observe the instruments.
  3. Your last attempt should be to climb as high as possible. During the climb, you should try to find the airspeed at which you get the maximum climb rate and observe the effects of altitude on climb rate. Make mental notes of the climb rates are various altitudes and the ceiling at which the plane can operate. Another good mental note to make is how long it took you to get there. This comes in handy if you know you've got enemy coming in at a certain altitude.
Do this again in at least the following airplanes and make a note of the stall speeds. These will be useful in later training. Plan your fuel load to allow for at least 15 minutes of climb to maximum altitude, plus 10 minutes of stall testing, plus 5-10 minutes of WEP. Use the WEP for the high altitude stall. The high altitude attempts will probably need around 50% (100% for Bf-109) fuel.

Spins

Spins are nothing more than stalls with an angular moment. In reality, it's when one wing is flying and one is stalled, causing a rotation about the stalled wing. In Air Warrior, it's a mode used to approximate the effects of a spin by taking the stalled plane and twirling it around some. In other words, you're still stalled and must recover from the stall, but you have to deal with the plane turning around and around as well. If you followed the instructions above, you didn't spin while practicing stalls. In Air Warrior, a spin will occur if you stall while in a turn or rolling or sometimes just when the wings aren't level.

Just as with stalls, each plane has it's own spin characteristics and procedures for recovering. They are all similar in that you must reduce the angle of attack and you must stop the rotation. However, some are easier to do this with than others.

Recovery from a spin is similar to a stall. You must reduce the angle of attack. In addition, you must stop the rotation. This is done by stomping on the rudder pedals opposite the direction of rotation. Some people also use opposite aileron, though in a real plane, this would be foolhardy. In addition, using opposite aileron will tend to roll the airplane, which you may not want (actually rudder only also tends to roll the plane). Recovery does seem to be faster if you use aileron and rudder. The following is a list of steps to perform for spin recovery.

  1. You must reduce your angle of attack, so immediately center and push the stick all the way forward.
  2. Throttle back or shut the engine off if necessary to keep the oil pressure in the green or prevent damage if you can't.
  3. Determine the direction of spin. You may use the forward view if you are somewhat horizontal. The side views work well if you are nose down. However, the compass is probably the fastest and easiest reference.
  4. Apply rudder (and optionally aileron) opposite the direction of the spin. If you are using the compass, apply it in the direction the numbers are heading.
  5. When the stall warning light starts flashing, center the stick and rudders and begin to pull out. Be careful not to pull up too fast or you will stall and possibly spin again. This is difficult to remember in the heat of combat with an enemy behind you and closing, but you must not stall again.
  6. Apply power as necessary (starting engine, throttling up, etc.) to keep speed up. Don't throttle up if you are nose down at 500 feet. You need a tight turn radius, not airspeed, at that point. If you had to shut the engine off to prevent damage, you will probably want to wait a short bit while under positive G forces to allow the oil to pool up before starting. Otherwise you will damage your engine during the restart.
  7. Establish a positive climb rate or maneuver as appropriate if you have sufficient altitude.
I really don't want to say this, but if you are to survive in the arena, you'll need to know this. Using just the rudder to stop a spin is the slowest form of recovery in AW. In fact, it's almost 2-4 times slower than using opposite aileron and opposite rudder together. This is totally bogus and I wouldn't expect it to stay this way, but for now, you should probably practice using both.

In addition, there are spin warriors out there who use the rotation of the spin to gain angles on you. They are able to control the start and stop of a spin with enough precision to essentially warp to your six and are typically found flying the FW190. Beware of these people and woe to you if you are one of them.

Common problems in stopping the rotation are:

Some planes may not recover well unless the throttle is retarded. Others need the throttle retarded or the engine shut off during a spin due to oil pressure problems. The FW 190 is prone to a disorienting inverted spin (with an unrealistic normal recovery procedure) and the P-38 is prone to unrecoverable flat spins.

To combat the problem of judging the direction of the spin, get used to using the compass as a reference. It's always visible.

Practice

We now get to practice the horrible feeling of spinning and spin recovery. Entry altitude will be 10,000'. Enter the spin by entering a spiral climb [ glossary ] and increasing the pitch [ glossary ] until a stall occurs. Keep the turn shallow and use the pitch to reduce your airspeed to stall speed. A spin should follow the stall. If you have trouble getting the plane to spin, try a more agressive (e.g. steeper, more Gs) turn. Be sure to try recovery with rudder only, aileron only, and rudder and ailerons. Use whichever works best for you. Try this with both a left and right hand turn in at least the following aircraft: A zipped example film of spins in different aircraft and recovery is available. One example shows a spit pulling out too fast and entering a stall. Another shows recovery from inverted spins while another shows recovery with little or no visual reference to the spin direction.

Steep Turns and Acceleration

Before we get into accelerated stalls, we should look at the effect of steep turns on the aircraft and how altitude affects the performance of steep turns.

A turn happens because the lift vector [ glossary ] is rotated in the desired direction of a turn by rolling the plane some amount and pulling back on the stick. Pulling back on the stick increases the angle of attack which causes a corresponding increase in lift. However the lift vector is now pointing somewhere other than just straight up, so the airplanes wants to move in the new direction. In addition to an increase in lift, the Four Forces [ ref ] tell us we also get a corresponding increase in drag.

Of course, if you remove the high lift and drag, you will accelerate back to an equalized state of thrust and drag. Eventually, you may be dogfighting someone and realize it would be best to get out of Dodge. Knowing how fast your plane can accelerate will be important. There's two kinds of acceleration that we will talk about. When is level or 1G loaded acceleration and the other is unloaded or zero G acceleration.

In level acceleration you are using your excess thrust to accelerate the plane. This usually results in continual push of the nose down since less AOA is required to maintain your altitude as the airspeed rises.

In unloaded acceleration, you push the nose down (assuming normal flight attitude) until the G meter reads 0. This reduces your AOA to a minimum, therefore reducing the drag associated with that lift. In addition, you will probably be using gravity assist to accelerate. You must watch your oil pressure when doing this or you will ruin your engine. Unloaded acceleration is faster than level acceleration.

Practice

Some planes are more affected by steep turns than others. In addition, altitude also has an affect. Use the following planes to experiment with steep turns. Practice the turns by climbing first to 5,000 feet, then leveling for speed. Roll the aircraft approximately 60-80 degrees and pull back on the stick enough to maintain level flight. Try not to let your plane stall by pulling back to much on the stick. Attempt to maintain as many Gs as you can without stalling or blacking out. What happens to your G loading, airspeed, and turn rate? Try to maintain your best sustained turn rate (not necessarily the most Gs). Roll into the opposite direction and try some more. Lastly, roll level and check your how long it takes you to accelerate to your maximum speed and make a note of that speed. Try this again at 15,000' and 25,000'. What did you notice? Try unloaded accelerations at various altitudes on the way down from your highest steep turn. [ ref performance charts here? ]

Accelerated Stalls

It's important to return to the point that stalls can occur at any airspeed, weight, and attitude. You should keep this in mind as you practice vertical maneuvers later. We will explore accelerated stalls here.

The amount of Gs you are pulling affects your stall speed. The more Gs, the higher your stall speed will be. The reason for this is pretty simple when you think about it. It takes a certain amount of AOA for your plane to fly level (1 G) at a given speed. This amount is whatever it takes to produce enough lift to counter the weight of the aircraft. If your plane was twice as heavy, it would require either more airspeed or more AOA to produce the extra lift needed to support the extra weight. The more airspeed you can get, the less AOA is needed, the more AOA is used, the less airspeed is needed. At some point though, if you weigh something down heavy enough, there will be a point at which you have no more AOA to use and your airspeed won't make up the difference in lift required to stay in the air. An example of this is the stall speed for a B-17. A light B-17 with less than 10% fuel and no bombs loaded has a stall speed of approximately 50 kts. If you load it full of fuel and have eggs on board, the stall speed rises up to ~75 kts. Try it. Given the ~50% increase in stall speed and the chart below, what can you deduce about the empty versus full weight of the B-17?

The same principle holds for when you are pulling Gs. When pulling 4 Gs, your plane acts as if it is four times its weight and you must use an appropriate increased angle of attack or airspeed to support the perceived additional weight. You can only use up to the maximum AOA before stalling, so supporting the G load must be done using airspeed.

The necessary increase in angle of attack (up to the maximum) required to support the G load causes a substantial increase in the stall speed. In fact, you can estimate the approximate stall speed by multiplying the 1G stall speed by the square root of your G loading. The table below shows the effect of G load on an aircraft which stalls at 75 kts in level flight.

Effect of G Load on Stall Speed
G Load Stall Factor Stall Speed
11.075 kts
21.4106 kts
31.7130 kts
42.0150 kts
52.2167 kts
93.0225 kts

Practice

We will now practice an accelerated stall. In this example, you should take a P-47 with a similar configuration to that used in your stall practice. Climb to 10,000' and level out to gain speed. At about 225 kts roll for a level left or right horizontal turn and try to work your way up to 4 Gs. Watch the airspeed, G meter and stall indicator. Try to predict when the stall is about to occur. Are you able to do this reliably? Did you find a correlation between the G meter and stall warning indicator? Try the same thing in other planes of your choice.

Roll

Roll rate controls your ability to change directions quickly. The faster you can change directions, the better your chances of escape when on the defensive and the better your chances are of countering direction changes when on the offensive. This can be particularly important in the arena when warps [ glossary ] can cause substantial direction changes in the blink of an eye.

There are two things which can affect the inherent roll rate of your plane. These are airspeed and rudder input.

The stick controls your ailerons, the ailerons alter the lift of each wing segment (left, right). The side with the greater lift rises. The more stick is fed in, the more the effective angle of attack is changed and therefore the more lift you get. Also, the faster you go, the more lift is generated. The more lift you get, the faster you roll. Conversely, the less stick or airspeed, the less lift there is and of course you roll slower.

Sometimes, however, you can go too fast and the stick forces required to deflect an aileron will become too great and your roll rate will decrease with speed. This can also affect elevator movement.

The rudder can effect roll rate by using wing dihedral [ ref ] to increase lift. The greater the dihedral of a wing, the more it will be affected by the rudder. To do this, you apply full aileron and rudder in the direction you want to pull and pull back slightly on the stick.

Practice

Climb to approximately 15,000' and use level and unloaded accelerations to reach the following speeds: using the following planes Try both unassisted rolls as well as rudder assisted rolls at these speeds. Make mental notes of which speeds the roll characteristics of each plane change.

Loop

The loop is a common occurrence when two opponents get into a turning fight. It is an energy efficient maneuver used to trade airspeed for altitude and altitude for airspeed while changing direction. In fact, a loop is nothing more than a horizontal turn flipped on end.

A loop has an interesting difference though. While going up, gravity is pulling you back down removing an extra 1 G load from you, but while going down, it is pulling on you adding an additional 1 G load. This, along with airspeed changes, means you will not be able to pull a constant G load all the way around. The planes we fly in Air Warrior just don't have the power to do that. There will probably be a 2 or more G difference between the bottom and top of the loop. If you try to pull a constant G load all the way around, you will probably stall somewhere on the way up.

Practice

Pick several planes such as the P-51, FW, Zeke, and Bf109 to try the loop with. Climb to 5000' and level out for speed. Try to start with an entry speed of 220 kts or so. Determine how long it takes to complete a loop and how much altitude is used. Work your way down to find the minimum entry speed you can start a loop with an still be able to nurse it over the top. What has it done to your altitude and time to complete a loop? Once you have found this speed, try adding 1 or 2 notches of flap just before you go over the top to see what effect that has. Does this help any? Does it lower your entry speed? Decrease the time to complete the loop? Slow your airspeed even more and cause a stall?

Try the above again with different airplanes and also at 15,000' and 25,000'.

Immelman

The Immelman is a maneuver used to trade airspeed for altitude while reversing or changing the direction of your flight. It is similar to the first half of a loop, except your you roll upright at the top. This puts you on a heading 180 degrees from where you started. A variation of this includes a roll during the vertical portion so that you end up on any heading you choose.

The Immelman maintains your energy much better than a flat turn. This will become very important once you begin dogfighting. Energy is life. If you lose it, you will likely die.

Split S

This Split S is the opposite of the Immelman and similar to the back half of a loop with a roll to inverted to enter the maneuver. It is used to trade altitude for airspeed and usually you end up on a heading 180 degrees from where you started. Again, a variation of this includes rolling during the vertical portion to put you on some other heading.

While the Immelman maintains your energy better than a flat turn, it also leaves you slow at the top of the maneuver and being slow with enemy around can make you an easy target. The Split S allows you to burn energy [ glossary ] for turn rate [ glossary ] in a high G vertical reversal or it allows you to gain speed in a low G vertical turn.

Practice

To practice this, pick a few planes such as the P-51, Spit, FW, Zeke, etc. and try entering a split s from various altitudes and airspeeds. Find the minimum altitude you may use to enter a split s for each plane at typical combat speeds (e.g. 150 turn fight and 220 extension [ glossary ]).

Choosing Your Mount and Continued Practice

At this point in time, you have been exposed to the basic mechanics of flight in a variety of airplanes. To become proficient, you should now start concentrating on a particular plane to learn it well. You will still want to fly other planes to understand their strengths and weaknesses, but you should pick one to fly more than the others so that you can become an expert at using it. If you want to know more about the characteristics of each plane before choosing, you may want to read Twist's description of the fighters of Air Warrior. [ Need a -1 section? ]

Continue practicing spins, loops, immelmans and the split s until you are proficient at it and have a good understanding of the limits of your mount and a decent understanding of the limits of other planes. You will also want to start practicing oblique maneuvers. Obliques are not carried out in strictly the pure vertical or pure horizontal. They are tilted to some degree. An example is when you might want to use a loop, but don't have the airspeed to do it purely in the vertical. In this case, you may want to tilt it over some to reduce the distance between the top and bottom altitude.

Test

Congratulations on what I hope will be a successful completion of this section. You now should be able to maneuver at the limits without digging too many potholes. :-)

When you are ready to take your test, click here. You will be given the test, the test will be graded and you will be informed of the questions you missed and the areas you need to review. You may review and retest if you like or continue on with the next phase of your training, Aerobatics.

There are lots of additional places to go for basic assistance. The following are all recommended reading.
Last modified: Wed Nov 29 13:58:50 CST 1995
Jim Knutson (Red Beard), knutson@cactus.org