Some twin-engined bombers were fully aerobatic, although the amount of fuel and bombload at any given moment might preclude some of the more violent manouvres. Bear in mind that any plane stressed for dive-bombing duties shouldn't find a loop beyond its abilities, so long as it either has sufficient excess power or goes into the loop after an initial dive. AFAIK, the Ju88 and G4M were both very nimble and intrinsically capable of loops and barrel rolls; I'd be surprised if the same wasnt true of the Ki67 and B25, plus the Blenheim, A26 and B26. (Probably others, too)
HOWEVER: the pilots manual sfor planes list manouvres that are prohibited. For example, loops, spins, rolls,inverted flight, vertical banks and Immelmans were prohibited for pilots of the B25. The reason for this is becausethose manouvres are, to a greater or lesser degree dangerous, the more so the more heavily laden the plane is. If all goes well on a mission, a bomber pilot shouldn't NEED toperform violent manouvres - and lets face it, it'd be an unlucky fighter pilot that couldnt match a bombers manouvres!
Even some larger bombers were capable, under the right circumstances, of some surprising aerobatics. IIRC the Lancaster could be barrel-rolled, although I havent heard of one being looped in RL, although I have twice performed that feat with the AH Lancaster (and several times with the WB B17. Havent tried it with the AH B17).
With regard to the realism orotherwise of buffs using violent manouvres to evade fighters in AH, especially in the MA, I can only say that I have little sympathy for the affected fighter pilots. Why? because AH is so seriously and ludicrously biased towards fighters and fighter gameplay that outside of historic refight scenarios I'd countenance, and indeed HAVE pulled every aerobatic trick in the book in order to attempt to survive fighters attentions. Usually unsuccsesfully, but every now and then a minor miracle occurrs.
If you dont want buffs doing unrealisticmanouvres toprevent you from a chance at killing them, then bug HTC for Otto gunnery (so we dont die whilst using the bombsight just because there arent any human gunners aboard), more realistic damage modelling in its effects (IMO, guns are too lethal and/or planes too easily damaged - probably to cater for the "Iwanna kill NOW!" dweebs), plus moreacuratemodelling of bomber loadouts, and - engine overheating if engines are run at more than 90% throttle for too long. Also doing away with GPS and replacing it with some system that doesnt let fighter pilots get completelylost, whilst allowing the effortsof buff navigators to navigate properly to be rewarded would help. Oh, and targets that stay down for a sensible amount of time and have sensible effects in the arena(instead of this 15 mins down lunacy) would help, too. Maybe giving buffpilots a decent rewardf or their efforts in perk points would help, too, for those that are bothered about perk points.
In short - make buffing a better experience for buff pilots, more of us will be encouraged to fly em more often, and wont feel we have to fight sofranticallytosuriveevery encounter. As things are, and have been aslong as I've been in AH, flying buffs in the MA is close to signing up for virtual suicide for next to no reward. Fighter pilots in AH have it far too easy - as they have tended to in MMOLS since the year dot. Time to take the training wheels off those fighters and give the buffers a more rewarding game, which overall will enhance the fighter piloting experience.
Esme (stepping down from soapbox...) :-}