Deflection shooting

[Zoe Brain]

Simple rules for simulating deflection shooting:

1. If the peg to peg line crosses the target's rear edge - use normal rules.

2. If not, and it crosses the target's left edge, the target must be in the firer's right half arc, and firing is peg to peg not peg to base. Similarly, if it crosses the target's right edge, it must be in the firer's left half arc, and firing is peg to peg not peg to base.

3. If none of those apply (ie line crosses target's forward edge), firing is directly ahead only, but peg to base not peg to peg.

See diagram below, it's more simple than it appears, green indicates target area, red firing arc, in each case.

59905

[nillu]

Hi. It's quite intresting. Arc of fire gives us lack of realism sometimes. So rule may be very usefull. But...

I tried to understand those rules but I don't know if I get it right with rear and forward edge. What's the story with the edges. Could you focus on it?

And what about firing into real thing rule? Can I mix it with your rules (am I able to shot to real plane, not to peg only with your rules or in such case it has to be modified?

Last question - have you tested it?

[IRM]

I'm sure she has :)

I gave it several tries earlier on, it's pretty straightforward in practice and (obviously) makes anticipating target movement more of a challenge. Nieuports, Fokker Triplanes and other agile aircraft appear to get a bit of a boost, which makes up for their relative fragility when matched with their contemporaries. I'm betting DVIIs are going to be downright evil.

So :thumbsup:

Modified it a little for flexible guns (normal rules for front and rear, otherwise the same half-arc rule as Zoe's). Any thoughts on that, Zoe ?

[Zoe Brain]

It's most important for WWII, where speeds were 2-3 times that of WWI. While deflection plays a role in WWI, some back-of-the-envelope calculations show that in the most extreme cases of air-to-air fighting, you have to aim ~ 2 plane lengths ahead of the target at extreme range and with maximum deflection. Moreover, kicking the rudder slightly to yaw the aircraft for a second or two won't change vector much at 100 mph.

Consider - muzzle velocity is on the order of 1000 m/sec. After 1 sec, velocity is on the order of 500 m/sec. In that time, the bullet has travelled about 700m, and will drop about 2.5m. That means time of flight to 200m, max effective range, is maybe 3/10 of a second, with drop 0.5m.

A crossing target at 180 km/h moves 3km in a minute, 50m in a second. So it will move 15 metres. A Sopwith Camel - a fairly short aircraft - has length of 6m. The optimal aimpoint is therefore about 2 plane lengths in front of the nose, and about 0.5m above it, level with the top wing. A misjudgement by 25% will still hit.

For ranges that are more usual, and crossings not at maximum deflection, half a plane length and forget about bullet drop.

Now consider WWII - a crossing target at 540km/h moves 45 metres in 1/3 sec. A Spitfire has a length of 9 metres, so you have to shoot 5 plane lengths ahead. Worse, range is more likely to be 350m, leading to a time of flight of 1/2 sec. So you must shoot nearly 7 plane lengths ahead. A misjudgement by 25% is a clean miss.

Worse, if you have mixed guns that are not ballistically matched, your cannon may arrive in 1/3 of a sec, your mgs 1/2 sec, so your cannon shells miss in front, your mg bullets miss behind. Or vice-versa if using low-velocity cannon at lesser ranges.

Which is why 20mm Hispano-suiza and other high-velocity cannon were far more effective when teamed with 12.7mm or 14.5mm Mgs, which had more similar ballistic characteristics to them than 7-7.9mm rifle bullets.

Anyway, in game terms, things happen a bit more slowly in WWI, deflection isn't much of problem, and kicking the rudder a bit to adjust aim is easy. So you can ignore deflection.

In WWII, reaction times are shorter, deflection shots MUCH more difficult, and "kicking the rudder" might cause your plane to gyrate wildly - after a delay.

[Zoe Brain]

And what about firing into real thing rule?

The ground scale in WWI is about 1:1000. The ground scale in WWII about double that.
If using 1:1200 models or 1:2400 models for WWII, then "firing at the real thing" might be justifiable. Otherwise "shoot at the peg" unless WWI or not using deflection shooting in WWII.