Whipsnade asked for specifics: "Pick a Traveller ship combat system, stick to it, and we'll show why your ideas don't work." Just for fun let's try talking in specifics using the CT system in The Traveller Book (TTB) which should match the LBB2 system..
Given:
A size 8 world with a size 1 moon orbiting at 500,000 km.
Planetary defense consists of 40 Fighters (10 dTons, 6G, TL 12, with a model 3 computer, triple missile racks, 3xHE and 6xNuke missiles). All fighters are based at the Ground Port and 2 are in orbit at any moment (on patrol). The ground spaceport mounts the equivalent of 10 Triple Missile Turrets and 10 triple Pulse Laser Turrets for planetary defense. [EDIT: The Ground based defenses in my example are to answer the inevitable question about why the pirate does not attack the Port instead of the Ships. ]
A pirate ship (400 dTon Patrol Cruiser) is hiding in a lunar crater on the far side and scans for incoming ships.
COMBAT: Let’s use TURNS to measure time (1 Turn = 1000 seconds). Rather than measuring distances in mm of game scale (since we do not have a tabletop) let us measure distances in KILOMETERS where 100 mm game scale = 10,000 km in real distance. One G of acceleration is equal to 10,000 km per turn. [from TTB, pg. 72]
An unarmed Fat Trader arrives at the 100 diameter limit with no velocity. From pg. 54 of TTB, the Fat Trader is 1,280,000 km from the world and will require 372 minutes to travel to the port at 1G. For the sake of simplicity, assume that the path of the merchant will pass within 50,000 km of the moon on a straight line course to the dirt-side port. The 372 minutes = 22,320 seconds = 22.3 turns to arrive at port.
DETECTION [from TTB, pg. 75]: “Commercial or privately owned ships [like the Fat Trader] can detect other ships up to one-half light-second (1,500mm) away [1500mm = 150,000 km]. Military or scout ships [like the Fighters and the Pirate] can detect other ships up to two light-seconds (6,000mm) away [6000mm = 600,000 km]. Tracking: Once detected, a vessel can be tracked by another ship up to three light-seconds (9,000mm) away [9000mm = 900,000 km].”
TURN 0: The Fat Trader arrives and begins heading towards the port, fat and dumb. The Fat Trader is roughly 780,000 km from the Pirate – neither ship can detect the other.
TURN 1: The Fat Trader accelerates to 10,000 km per turn and is roughly 770,000 km from the Pirate – neither ship can detect the other.
TURN 2: The Fat Trader accelerates to 20,000 km per turn and is roughly 750,000 km from the Pirate – neither ship can detect the other.
TURN 3: The Fat Trader accelerates to 30,000 km per turn and is roughly 720,000 km from the Pirate – neither ship can detect the other.
TURN 4: The Fat Trader accelerates to 40,000 km per turn and is roughly 680,000 km from the Pirate – neither ship can detect the other.
TURN 5: The Fat Trader accelerates to 50,000 km per turn and is roughly 630,000 km from the Pirate – neither ship can detect the other.
TURN 6: The Fat Trader accelerates to 60,000 km per turn and is roughly 570,000 km from the Pirate. The Pirate detects the Fat Trader but the Fat Trader cannot detect the pirate.
TURN 7: The Fat Trader accelerates to 70,000 km per turn and is roughly 500,000 km from the Moon and 1,000,000 km from the planet. The Pirate orders the Fat Trader to halt and be boarded and fires a warning shot. The Starport hears the transmission and orders the two fighters in orbit to respond while scrambling another 18 fighters. The fighters can detect the Pirate and are able to launch against it. Since the fighters can detect it, the planetary ground batteries can also track it up to 900,000 km away.
HELP ME… I see how the pirate can destroy the Fat Trader, but even if the Fat Trader wanted to stop and surrender, it would require 7 turns of deceleration and would stop another 280,000 km closer to the planet (a range of 720,000 km from the planet). The fighters will arrive with zero velocity at the stopped Fat Trader in about 7.2 Turns (120 minutes).
The Pirate will need to intercept and board the Fat Trader while the Fat Trader decelerates and will be subject to attack by the planetary fighters for the entire time it is attacking and boarding the Fat Trader – and it still needs to escape (under fire by 20 nuclear armed fighters).
Perhaps someone would care to suggest a different plan of attack?