Problems with COACC
From MegaTravellerWiki
Close Orbit and Airspace Control Command adds creation rules for Industrial and Pre-Stellar aircraft; the Referee's Manual provides rules only for vehicles from Industrial civilisations or better and for spaceships and starships of Early-Stellar or better, so COACC is a welcome addition to the MegaTraveller universe for any campaign run on a smaller scale which can potentially involve air-to-air combat. However, there are some problems with the system as presented.
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Damage Scale?
The first major problem is that aircraft in COACC are not specifically given a scale for what sort of damage people inflict against them. If one assumes that they are vehicle scale, they are considerably more durable than ordinary vehicles of their size: for instance, a six-tonne vehicle from the RM will have no more than a 2/5 hull rating, but a seven-tonne Cheyenne-class jet fighter (a takeoff of the MiG-17) from COACC has a staggering 28/70 hull rating. Based on these figures alone, it is evident that aircraft generated in COACC are damaged by personal weapons directly and inflict damage on a personal scale with their weapons -- this is supported by the line "apply as indicated in the MegaTraveller Players' Manual" (p. 58, COACC) under the strafing damage. The same line is also repeated later for bomb damage.
The reason for the discrepancy is due to the fact that aircraft in COACC are designed from their tonnage, while craft and vehicles in the Referee's Manual are designed from their volume. To calculate hull rating, aircraft then have their mass in tonnes multiplied by 60 to determine volume in cubic metres / kilolitres. This produces excellent shipping dimensions of aircraft, but the "divide volume by fifteen to determine damage rating" rule from the Referee's Manual assumes a solid box of the given volume, and aircraft are certainly not solid within the rectangular box they occupy! When COACC takes the same divide-by-fifteen rule, the results are exorbitantly larger than hull rating of vehicles.
Compare a 55-tonne Wheeled ATV with a Displacement of 10 (135 kilolitres) versus a 70-tonne Anchorage with a Displacement of 200 (2700 kilolitres) and you quickly see that the volume of the aircraft is twenty times that of the ATV but the mass is barely over 1.25 times the ATV's. Though the scale of volume-to-mass is realistically accurate, if hull integrity is computed from volume instead of mass a soft-skinned aircraft is definitely getting the sweeter deal compared to the solid steel, heavily-armoured ground vehicle!
The most basic solution is to assume that aircraft are on the personal damage scale: personal weapons will cause their rated damage to aircraft, and aircraft hull ratings and engine ratings are not multiplied by ten before a personal-scale scenario begins. A more advanced solution alters their damage ratings to be appropriate and is featured as part of my aircraft durability system.
Engines Disabled Yet Again?
The second major problem is that all aircraft in COACC have glass jaws, specifically their engines. Even against a gigantic 1000/2500 bomber, one in three hits will strike the engines, such that only a few dozen bullets will be needed to bring the craft down entirely.
For smaller aircraft, aircraft stand a fair chance of being disabled due to airframe damage and falling into their death spiral. For larger aircraft, however, bringing the aircraft down due to damage to the airframe almost never happens.
Functionally, the only real hit point counter of larger aircraft is the number of engines, so a large aircraft with two powerful engines is considerably weaker than a smaller aircraft with four smaller engines. This isn't completely inaccurate: an aircraft with more engines can survive longer than an aircraft with fewer engines, because the loss of three engines on a four-engine bomber means the aircraft can still fly forward on just one engine. However, it is also realistically impossible to hit the engines this effectively. Anyone who has played a combat flight simulator will understand just how difficult it is to place bullets and missiles directly into an enemy plane's engines to bring it down. A fighter pilot in World War II attacking a bomber from six o'clock high would find it next to impossible to plant any bullets into the bomber's engines, so the pilot would concentrate on the much-more inviting targets: the wings and fuselage. Incidental bullets that pierced the wings and hit the engines or bullets that ruptured the fuel tanks inside the wings would be side effects at best—very beneficial to bringing down the aircraft, but not deliberate.
My attempt to address this issue is part of my aircraft durability system as well.
Bombs Bursting Like Air?
The amount of damage inflicted by bombs at ground zero seems somewhat conservative. A 250-kilogram bomb inflicts 34 damage points in a Danger Space of 45 metres. This is certainly enough to kill any unarmoured person within that radius... but what about against a vehicle or starship? Logic tells me that dropping a bomb on top of a landed Ship's Boat would cause more damage than a mere eighth of the operative portion of the Boat's 270/675 rating. If a bomb landed on a ground car, the bomb would be enough to disable the 20/50 ground car, but not nearly enough to destroy it outright.
Ideally, bombs in COACC should have two damage values: one to represent the effect of being caught at ground zero of the explosion, and one to represent the effect of being caught by the explosion's shrapnel and shockwave. Alternatively, one can simply compute the bomb as if it were a demolition charge of standard explosives if it manages to land directly on a target.
Using the demolition charts on p.103 of the Referee's Manual, it's possible to cross-reference the explosive force of 250 kilograms of explosives against a ground car's armour rating. It takes 265 kilograms of explosives to cause 250 damage points and breach a hole 1 metre in diameter against a ground car's armour rating of 4: with only 250 kilograms on hand, one can just reduce the damage and the breach diameter according to that percentage (approximately 94.3%).
At ground zero of a 250-kilogram explosion of trinitrotoluene (TL5 standard explosive), a unit with an armour rating of 4 should suffer {250*0.943} 235 points of damage -- against a ground car's 40/90 total rating (including its locomotion and engine), this is more than enough to shatter the ground car into shrapnel, killing all occupants.
In all likelihood, the bomb would miss the ground car and simply disable the car with 34 points of damage, sending it tumbling end over end and landing in a messy heap -- somewhat intact, but inoperable, breached to the atmosphere, and probably almost as expensive to repair as it would be to buy a new ground car. But if the bomb actually managed to land directly on the ground car, that's all she wrote: the car will exist as nothing more than shrapnel.
I haven't yet attempted to address this issue beyond the ideas posited above.
Spelling?
It's spelled "hangar"! The book spells it correctly in one paragraph on page 75, but everywhere else it is spelled "hanger".
