"What gets me is the yak-9u's, 109g2/g10, the la-5/7s, p51's and f4u's."
Of all those, only the La5 and the Yak should give you any trouble, as they are the closest match for a P-38.
Kweassa put a lot of info there, here's my .2 cents (shortened since Kweassa put most of the info up there already
):
Your first and foremost thing to do in the P38 is to know your plane's advantages and disadvantages vs your opponent's weaknesses and advantages.
Yak9U: Cons: Poor acceleration (compared to P38), very short range guns (aka, dangerous only under d400). Pro's: Yak will match P38 in low speed handling (under 150mph) and in High speed handling. Very small target.
To defeat the Yak, if you on the attacker role, fly the 38 as if it was a P-51. That is, come at him fast, do 1 pass, and extend, return if you need to. But always stay fast and dont let the bugger inside d500 of you. If the Yak is on the attacker role, your best chance is to get him on the deck and below 150 mph (sciscor, etc, just get him on the deck and slow him down). Once on the deck the 38's much superior acceleration will allow you to run away from it, yaks usually spray their ammo as you do this.
109g2: Cons: slightly worse turn rate, very poor low speed handling. Pros: Better dive rate, little better climb rate, very nice afterburner WEP.
The 109G2 is rather easy to beat, just do lazy lag persuit and dont follow it on dives. Once it begins to turn (109g2's love to try and do the yo-yo dance), keep taking potshots with the 50's, you will score a crippling hit easy enough.
109G10 cons: very poor turn rate and low speed handling. Cons: Monstrous climb rate and acceleration, very nasty guns.
109G10s do one thing: They climb and try to rope you or hammerhead you. Ironically, this 109 is the easiest to beat since it is the most predictable. If it noses up to climb, you just nose up at half his climb, keep your speed at 250 always, no matter if the 109 is pulling up up up and away. The g10's always climb until they see you like at d800 then they turn and do a dive attack on you. If you kept your speed at 250, the P-38 will have enough speed to do a half-turn to evade the bounce and then take potshots at the 109g10 as it dives. The 109 usually has only 150mph when it dives past you, so your 250mph and your 1.2k .50's should allow you to score a few shots . Dont EVER follow the g10 on the dive, always let him dive away.
La5 : cons: poor acceleration, crappy short range guns. Pros: Very manouverable, small, good dive rate.
La5s can be beat in the vertical. Dont ever get into a turn or E-fight with the things, they will eat you.
La7: cons: Poor turn rate, horrible low speed handling, short range guns. Pro: Monstrous acceleration, high top speed, great climb rate under 20k.
If you see an La7, DROOL. Sciscors will kill these things so easy its just not funny.
P-51: Cons: Bad acceleration, poor climb rate. Pros: Excellent dive and high speed handling, excellent E retention.
P51's are will seriously test your SA. There are only 2 rules vs these things: If under 25k, you better get them turning or hope they do something stupid..like turn with you or loop you. If over 25k, the P51 is only a danger on the first one or 2 passes it makes at you, after that it wont be able to climb to do its high speed passes, then its left with 2 options: Turn or dive and run. If they dive and run YOU WIN! If they turn, then the P-38's fowler flaps turn the thing into a virtual Zero up that high, eat his arse.
So far the best all-around tactic ive found vs the P51 is to force HO's. Remember, his only tactic vs you is to dive at high speed and hit you and run away. If you deny his attack by turning to HO him, the pony driver is neutralized unless he wants to try his luck. Most do and die to your 1.4k .50 cals that dont suffer from dispersion. *hint*
F4U's:
Cons: Very poor low speed handling, poor climb rate, very poor acceleration. Pro: slightly better dive rate, good turn rate.
F4U's are easy to beat. Just sciscor or go vertical with them. Word of caution, dont vertical a C-Hog, those maggots just need 1 ping to git ya. And always remember, your superior acceleration means that if you get it low and slow, he's at your mercy.