[Chock]

Another thing you would also have to consider would be the range at which you had harmonised the guns - assuming you have two of them that are the same. Not always as simple as it seems - the SE5 had two guns, but the DV and the Sopwith Camel for example, had a pair of guns, which is slightly different where harmonising is concerned.

Even though both guns on the SE5 fired the same ammo, there would probably be less point in trying to harmonise the guns on an SE5, as it is likely the Lewis gun mounting (especially the early one) would flex and spray things about a bit more than would the Vickers, which was bolted to the airframe, with consequently less chance for leverage on the mountings as it fired. This was the case with the fixed Spandaus on most German WW1 fighters too. Flexing of guns on auxiliary mountings is something which has affected numerous fighters over the years, notably the underwing cannon pods on the bf109G and the centreline gun pods on several jet fighters, such as F4 Phantom variants without an internal gun.

From a ballistics standpoint, and as most field target shooters (and probably snipers) know, how much ballistic drops affects matters is altered depending on whether you fire at an upwards or downwards angle, since when firing steeply downward, the gravity which causes ballistic drop effectively adds to the acceleration of the bullet rather than altering its trajectory, whereas when firing upwards the same distance, it decelerates the bullet and alters the ballistic drop effect by making the bullet travel through 'more gravity', since it is going a bit slower, but bizarrely, not by as much as it does when firing horizontally, since the gravity vector is closer to the trajectory line when firing upwards.

That effect may be more relevant to long range shooters on the ground than it would be to aeroplanes, since the ranges would probably render ballistic drop of little relevance when at close range in a dogfight, although it might have a bearing on firing a Lewis gun upwards at a two seater from underneath, and it could possibly be useful in a steep diving attack, especially in something like a SPAD, where you could effectively add up to around 280 mph to the muzzle velocity of your bullets if you fired when in a vertical dive.

Also likely to alter things a little, is the air density at altitude. At 18,000 feet, your bullets would encounter less air resistance than they'd get when being ranged on the ground, so ballistic drop would probably be a bit less when up high in a fight.

So there's a few reasons to disregard all that confusing stuff and simply fly right up someone's ass, where you could hardly miss.

Al