Well, I stand corrected! I've tried the "dive" flaps, 6 ways to Sunday, and can't tell any difference with or with-out flap application. Guess I will have to go back to TA and do some more test!
You're not using them correctly. The P-38L dive flaps work in game as they did in real life, the problem is that players deploy them either too early (when speeds don't require the flaps) or deploy them too late in the dive thinking that deploying them will automatically make the P-38 recover.
It's best to deploy the flaps right before you start your dive or immediately afterwards. Deploying them in mid-dive reduces the effectiveness of the dive flaps so you want to make sure you deploy them when you begin your dive. Just a side note...if you find that you need to deploy the dive flaps in a dive, you screwed up. The P-38 can dive at high speeds without the aid of the dive flaps to recover, you just need to take care and control your speed in the dive, its how the dedicated P-38J drivers dive their Lightnings. Decrease throttle and use your rudders to help control your speed in a dive.
ack-ack