If you can't run, and if you have to fight - always turn and meet your attack. Never let an enemy get a chance to fire behind you.
Now, this is a bit difficult to explain, since the concept of "turning and meeting the attack" sounds awfully simular to a "dweebey HO attempt". Besides, this method is in form, very different from the conventional method of "extending away, saving E, and cutting down initial E differences" (although in basic principle, it is not very different).
By turning and meeting the attack, I don't mean you should go for a suicidal HO. Going for an unlikely HO shot will deter your energy state even worse, and HOs are something that a careful pilot should rather not choose to do.
The principle behind turning and meeting the attack is, "if the enemy has altitude advantage and performs a Boom and Zoom sequence on you, always try to give him the most difficult angle of the shot". It is easy for the enemy to aim your 4, 5, 6, 7, 8 oc angles. So, lure them into an angle which they have to take a difficult shot at 10, 11, 12, 1, 2 oc angles. By this you achieve this:
1) The enemy dropping down from a Boom sequence will have to take a shot at your front quarters at a fast speed, high rate of closure, in a steep dive and awkward bank angle. As you are facing him in a near HO angle, slightest move of your plane will result in a large change in his aim.
This will minimalize his chance of getting a shot onto you.
2) By always meeting the attack, instead of showing your rear quarters, you give him the impression that you are keep attempting a HO in an insane manner. (I myself have been accused countless times for being a "HO" dweeb from the pilots I have shot down or chased away - when in truth I had no intention of going for a HO, or haven't fired even a single shot)
This will either;
(a) annoy him, make him get mad and irrational, getting aggressive pass after each pass, thus, prone to making a big-time mistake
(b) make him become more careful than he needs to be, which just might buy you the advantage or a chance to escape.
3) The nature of the enemy's attack, and your flight path, in effect, gives out the most ideal situation for utilizing a defense/reversal attempt barrel-roll. Extending away from the enemy cuts down on the E difference, but gives out the most shallow and friendly angle for the attacker in shooting at you. It also gives the attacker enough time to think, estimate and counter your defensives. However, when you turn and meet the attack, the distance between you and the attacker closes very fast, which means his attack angle is getting steeper all the time. He doesn't have as much time to think what you are up to, as he will be in most cases concentrating on targetting.
Unlike attempting a barrel-roll against something chasing you, this situation is a bit less obvious and a lot less dangerous. Since the attacker BnZing you is always diving on you, there is no way for him to just 'slow down' during the dive and laugh at your barrel-roll attempt. If the enemy tries to counter the barrel roll by slowing down and latching behind you, he dismisses his E advantage with his own hands. And even stil,l in most cases, it is highly unlikely he will successfully latch onto you - because, as stated above, he is dropping in fast, in a steep angle, with high dangers of black out, and at the most unfavorable angle for maneuvering behind the target.
4) Pass after each pass, the enemy's E-state dissolves away in a tremendous rate. Though his acceleration speed is high(because he is in a steep dive), if he misses(which is veryy likely), he will have to;
(a) either pull off at a very abrupt manner(which kills E fast)
(b) extend away level(buys you enough time to prepare for the next attack)
(c) or continue the dive(which puts you in the advantage of getting behind his back)
But there is also high risk involved in turning and meeting the attack. Turning onto him drains your energy, and once you have turned into the enemy timing your escape is very difficult. The enemy can also try and control his dive speed and angle, or he might try to lure you instead by making you turn very steep and upwards into him, thus making you vulnerable for a "Hammerhead(Rope-a-dope)" sequence. Meeting the attack, also requires good judgement - timing is essential, and judging whether you meet the attack in a purely defensive manner or in an attempt to force a reversal, requires a lot of experience.
Thus, turning and meeting the attack is a game of E-balance: you drain your energy in the attempt to meet the attack, and in turn, try to force a situation where the enemy drains even more E than you. Compared to the method of extending away from the attack, meeting the attack is therefore, a much more aggressive form of defense where you force him to bleed E, instead of letting the E difference diminish in a passive manner. This means if you succeed, you will be more highly rewarded, but if you fail, the consequences will be more serious.
Turning and meeting the attack is usually performed by the pilots who use generally a more maneuverable, but slower plane. All those instances of Spitfires gaining the edge over the enemy who started off higher has a lot to do with meeting the attack. People will resent them and call them "HO dweebs". But in my experience, there is a recognizable difference between the "true HO dweebs", and the real ace pilots. When fighting against those pilots, each of their maneuver resembles an all-or-nothing HO attempt, but they move out of the HO line at the last minute time after time, and no matter how hard you try, they always seem to be coming at near HO angle - a very unsettling and uncomfortable situation for a BnZ attacker. After a few passes, you realize you have lost too much E to fight a more maneuverable craft, and have to withdraw.
Although generally a slower-but-more-maneuverable plane will use this tactic, this can be utilized by many planes. It is my favorite tactic in squaring off against high P-51s in a Bf109G-10 - in this case, the Bf109G-10 outturns the P-51s by a little margin, and climbs much better, which maximizes the advantages of meeting the attack. With each failed pass a P-51 loses E, but my G-10 gains altitude at a tremendous rate. After a 4~5 passes the G-10 easily accumulates enough advantage to follow the P-51 zooming up and reversing the tables.
Therefore, this tactic is to be used generally when you are in a slow and maneuverable plane, or when fighting against a higher plane with simular turning capabilities. It is not to be used against higher and more maneuverable planes(which are probably slower than you) - in this case, the conventional method of extending away is more effective.
