Radical Alternatives: How SHOULD Size and Speed/Range Affect Chance to Hit?

[Fred Brackin]

Originally Posted by Pursuivant

shooting at enemy fighters (say SM 3 to 5, traveling at relative speeds of 100 to 1,500 yards/meters per second, at ranges of 100 to 1,000 yards/meters). .

"SM 3 to 5" Only the Zero would have been SM 3 and you'd had to have rounded up a lot to get anything but the largest 4 engined bombers to SM 5.

"100 to 1500 yards/meters per second" There were no WWII fighters capable of flying at 3000 miles per hour. 100 to 200 yards per second.

1000 yards would have been very far for any aerial use of machine guns or even autocannon though it wouldn't have been so bad for ground use. 400 yards was more likely.

[Rupert]

Originally Posted by Fred Brackin

"SM 3 to 5" Only the Zero would have been SM 3 and you'd had to have rounded up a lot to get anything but the largest 4 engined bombers to SM 5.

The big strategic bombers had 40+ yard wingspans and were over 30 yards long. That's an easy SM+8. HT gives both the Mustang and the Fw190 as SM+6.

[Fred Brackin]

Originally Posted by Rupert

The big strategic bombers had 40+ yard wingspans and were over 30 yards long. That's an easy SM+8. HT gives both the Mustang and the Fw190 as SM+6.

3e sources thought of SM as a linear measure. I tend to think in Spaceships terms these days where SM is firmly tied to mass. Spaceships SM+3 is 3 tons, SM+4 is 10 tons and SM+5 is 30 tons. SM+8 would be 1000 tons.

[Rupert]

Originally Posted by Fred Brackin

3e sources thought of SM as a linear measure. I tend to think in Spaceships terms these days where SM is firmly tied to mass. Spaceships SM+3 is 3 tons, SM+4 is 10 tons and SM+5 is 30 tons. SM+8 would be 1000 tons.

Given we're talking about hitting the thing, size matters here, not mass, and aeroplanes are not very dense (especially WWII aircraft) and are thus large for their mass.

[Pursuivant]

Originally Posted by Fred Brackin

"SM 3 to 5" Only the Zero would have been SM 3 and you'd had to have rounded up a lot to get anything but the largest 4 engined bombers to SM 5.

P-38L had a wingspan of 49 feet = >15 yards = SM 5

Effective SM can be reduced by "angle off" between aircraft. For example, an aircraft which is quartering in on its target might effectively present just a fraction of its total maximum surface area. This particularly true for an airplane flying directly towards or away from its target at the same altitude. In that case, it would just present the front of the windscreen, engines, and wings; a much smaller target than if it were seen from the side or above.

[QUOTE=Fred Brackin;2304377]
"100 to 1500 yards/meters per second" There were no WWII fighters capable of flying at 3000 miles per hour. 100 to 200 yards per second.[QUOTE=Fred Brackin;2304377]

You're right. 1,500 yps is a typo. I meant to write 100-500 yps. While typical relative speeds were more like 100-200 yps, fast-moving aircraft fighting at high altitudes could effectively have relative speed modifiers of up to 1,000 mph.

For example, select two high-altitude, late 1944-era fighters at 35k+ altitude (e.g., Ta-152A vs. P-51D), in relatively steep dives. At that altitude, maximum level speed is over 400 mph and it's very easy to get into dives of over 500 mph. Select for one diving fighter doing a "direct merge" making an incredibly high deflection shot from what will eventually be the other fighter's 3 o'clock high position (i.e., a high side beam attack) at an opponent who is also booking along at 500+ mph. That gives a combined speed of 1,000+ mph or over 300 yps in GURPS terms, which goes to the 500 yps range band.

Realistically, you've also got both aircraft maneuvering in all three planes of maneuver and the attacker's angle of deflection is so great that when he sets up his attack he can't use his sights and still pull sufficient lead on his target. He might not even be able to see his target when he starts his attack! So, full penalties for the higher range band are entirely justified.

Originally Posted by Fred Brackin

1000 yards would have been very far for any aerial use of machine guns or even autocannon though it wouldn't have been so bad for ground use. 400 yards was more likely.

You're right, but one of the problems of high altitude air war was that aircrew didn't have any range references to allow them to quickly get accurate ranges on enemy aircraft. The thinner air also messed with perceptions because lack of moisture in the air made distant targets seem clearer, giving the illusion that they were closer than they really were.

This led to common situations where inexperienced pilots or gunners opened up on their targets at far too great a range. To counter this, aircrew were drilled on the dimensions of enemy AC and sights were designed so that a common enemy aircraft (typically, the Bf-109 for the Allies) completely filled the sight area at a given range. Using the those references, experienced gunners could the estimate smaller or larger distances for larger or smaller planes to perhaps +/-50 yards/meters.

More advanced reflector sights had concentric circular reticules placed so the reference aircraft's wingtips just touched the sides of a given reticule ring at known ranges. Late war sights (e.g., K-14 "Acemaker") allowed the reticule ring size to be adjusted to precisely match the dimensions of certain enemy aircraft, allowing much finer ranging estimates.

Of course, sights only work if you have minimal deflection so that the enemy stays in your sights from the beginning of your attack to the end, and if they're kind enough to not take serious evasive maneuvers.

At the other end of the scale, while a few WW2 pilots were noted for their ability to score hits at 1,000 yards or more (esp. vs. U.S. heavies), most aces got their kills by sneaking up on their foes, getting within 300 yard/meters of their target unseen with minimal angle-off and speed differential and then blasting them out of the sky.

Obviously, this is only of marginal utility to the typical GURPS small arms shootout, but it illustrates the sort of less common combat situation where GURPS standard combat rules strain to fit. It makes more sense for vehicular combat to be broken into 3-5 second combat rounds which better handle the sort of "OODA Loop" decisions that combat pilots and drivers face. For bigger vehicles and/or longer ranges, even longer turns might be appropriate.

[ErhnamDJ]

I'm still trying to digest everything in this thread.

Should any of this affect how lighting penalties work? Whatever happened with all the lighting stuff? Did that get hammered out?

[Anthony]

Originally Posted by ErhnamDJ

I'm still trying to digest everything in this thread.

Should any of this affect how lighting penalties work? Whatever happened with all the lighting stuff? Did that get hammered out?

Realistically, bad light does a couple of things, none of which are terribly well represented as a simple skill penalty:

1. Scotopic vision is lower resolution than photopic vision, limiting peak accuracy. This is not all that directly relevant at short ranges (20:2,000 vision is adequate to hit a human sized target at 10 yards) but is a problem at longer ranges.
2. Scotopic vision has a lower frame rate than photopic vision. This is a problem for moving objects that are moving erratically or aren't present for very long.
3. The above effects, along with loss of color vision, make target identification much harder, increasing the odds that you fail to recognize a target, or think a non-target is actually a target.