The easiest way is to raise your aim angles in your ALBATROSD3_***_DATA.INI file using NOTEPAD. The center value dictates hight.
// Internal Guns ---------------------------------------------------------
[internalGun1]
SystemType=FIXED_GUN
GunTypeName=7.92MM_SPANDAU_LMG08
InputName=FIRE_PRIMARY_GUN
GunGroup=1
MuzzlePosition=-0.14,0.50,0.60
LightPosition= -0.14,0.55,0.60
AimAngles=0.0,1.0,0.0 //---------CHANGE LINE TO THIS VALUE (or more)
MaxAmmo=350
EjectShells=FALSE
MinExtentPosition=-0.18,-0.59,0.51
MaxExtentPosition=-0.08, 0.50,0.66
GunFireAnimationID=7
Synchronized=TRUE
[internalGun2]
SystemType=FIXED_GUN
GunTypeName=7.92MM_SPANDAU_LMG08
InputName=FIRE_PRIMARY_GUN
GunGroup=2
MuzzlePosition= 0.14,0.50,0.60
LightPosition= 0.14,0.55,0.60
AimAngles=0.0,1.0,0.0 //---------CHANGE LINE TO THIS VALUE (or more)
MaxAmmo=350
EjectShells=FALSE
MinExtentPosition= 0.18,-0.59,0.51
MaxExtentPosition= 0.08, 0.50,0.66
GunFireAnimationID=8
Synchronized=TRUE