These work great as is.
I stated 15 degree, but I really meant away from each other, instead of parrallel like the hinged versions do.
When flying with the parabolic range extenders, it changes the pattern of your wifi signal to the aircraft. I have found over hundreds of flights that when maneuvering across your field LOS, especially when flying around homes to take photos, like I do mostly, I get better overall signal performance with the antennas canted out.
When thinking about how the parabolic windsurfers change the signal broadcast, by canted your antennas out, you get a broader spectrum of signal from up/down to left/right.
But that's just my experience.