This is just an Fyi for new players who are sick of being killed by them. If you're already an experienced player and/or know about it, ignore and continue scrolling.
Heavy Bombers have a specific spot that increases your damage to them. If you're attacking from below, it's pretty much right under the cockpit, but if you're attacking from behind, position yourself slightly diagonally and shoot the area around the windows of the cockpit.
This wasn't even a good attempt because i missed a decent number of shots, but i still did 122 damage (35 from the first burst) and took it out in just 2 seconds of actual shooting. Imagine how fast you can kill them if you hit the sweet spot perfectly.
PS: this also works with infantry/stationary weapons, which is why you sometimes kill them in one shot with the Tankgewehr, if you ever used it. Also dramatically increases the effectiveness of AA guns.
Hope this helps, enjoy your newfound knowledge :)