Aerobrakes go...

[tranenturm]

... which way?

[ajburges]

Mechanically, hardly matters. Choose the one you like more.

The air brakes they are based off of push air away instead of trying to catch it.

Mod will probably move this to the questions thread.

[katateochi]

They work either way round so it comes down to what looks right.

On aircraft I put them pointy end forward

But in other uses I've put them the otherway round, more scoop like;

[tranenturm]

Thx! Sorry about the wrong forum.

[Reactordrone]

I real life the orientation is due to actuator strength and whether you want the brake out permanently or temporarily. An F-15 pushes the brake up into the airflow then air pressure helps push it back down into the closed position but a snake eye retarded bomb tailfin will pop out the other way so that airflow helps to keep them open.

In game the actuator is always able to move the panel so it's largely down to aesthetics.

[problemecium]

Based on the part's default orientation I believe they're meant to go hinge-forward.

[Endersmens]

They are modeled after real life airbrakes, which are oriented like the first screenshot mentioned above. Pic of real thing:

[Vanamonde]

Moved to the section for nuts & bolts kind of questions.

[NathanKell]

Since lift is ignored for KSP stock airbrakes, orientation won't matter (the angle of attack is the same either way, just with a sign flip).

[Harry Rhodan]

... whooooooosh!