Aircraft customization is a feature of both Crimson Skies and Crimson Skies: High Road to Revenge. There are, however, noticable differences between the systems used in each game.
Crimson Skies[]
Crimson Skies featured a full customization system, allowing a pirate to build their entire aircraft from scratch. There were six areas of customization - airframe, engine, guns, armor, hardpoints and paint.
Airframe[]
Each of the eleven aircraft in the game can be selected here. Altering this choice will reset any other choices made. The airframe determines the maximum weight, the location of the guns, and the paint scheme choices.
Engine[]
Each airframe has three basic engine choices, then those same three again with nitro. The engine choices are, basically, slow-but-light, average, and fast-but-heavy. As a general rule, the mid-grade engine is the best choice unless you are attempting a specific design, such as a lightly-armed speeder or a slow-moving flying tank.
Guns[]
Each airframe has four gun slots, including any turret options. Each of these slots can be filled with either single or double machine guns, ranging in size from .30-cal "Zephyrs" to .70-cal "Goliaths". It is recommended to put guns on two gun slots that can be controlled by the player, and on all turrets (guns on turrets can not be controlled by the player, but they can cover fire arcs you can't normally reach and their accuracy is always 100%). The recommended number of guns is one per gun slot used. The recommended caliber is .60 (or .70 if it can be demonstrated that its precision isn't inherently lower than .60). The recommended ammunition choices are AP and DD on the two guns controlled by the player (use AP only to strip armor from aircrafts, use DD to finish them off and against everything else), and either slug or EX on the turret(s). If you find it too hard to switch guns mid-fight, consider rebinding F3 or F4 to a key that's more easily accessible to you. If for some reason that's not an option either, then your only alternative is to use a gun slot with 2x .60-cal. (or .70-cal.) guns with either AP or EX rounds. This, in addition to halving your damage per second, also halves the total damage you can deal before you run out of bullets; if this happens, you should either improve your accuracy, or bring a back-up gun (e.g. an additional .60-cal.).
Armor[]
There are four armor slots - nose, tail, right and left wing - and each slot can be equipped with a quantity of armor from 0-60 in 5-unit increments. Right and left wing allotments must be equal. As a rule, even a low-weight airframe such as the Hughes Bloodhawk can carry 50 points of armor on all four slots, and high armor should be a priority.
Hardpoints[]
An airframe can carry up to four hardpoints on each wing, for eight in total. Typically assigned last, pilots tend to equip as many hardpoints as they can carry once their engine, guns and armor choices are made, but rarely more than four in total, except on dedicated fighter-bombers such as the Balmoral or the Warhawk.
Paint[]
Each airframe has a number of paint schemes, usually based on users from the campaign mode. All airframes also have the Fortune Hunters scheme. The colors used in each scheme can be independently customized, as can the decals used on the nose, wings and tail. Paint and decals weigh nothing.
While each airframe and option cost a different amount of money, the limits of weight mean that most aircraft wind up costing between $10,000 and $12,000. However, an aircraft can be sold for the purchase price, meaning that aircraft can be created and scrapped without cost.
Customized craft can be freely used in online multiplayer, encouraging gamers to try to find the best combination of power, speed, armor and offensive capability.
Crimson Skies: High Road to Revenge[]
Unlike its predecessor, Crimson Skies: High Road to Revenge featured a greatly simplified - and much less flexible - aircraft "upgrade" system. In exchange for a specified quantity of Upgrade Tokens and cash, nine of the ten available aircraft could be upgraded, once, with improved speed, defence and offensive capability, along with a red-black-and-silver Fortune Hunters paint scheme. This "one-shot" upgrade system was widely derided as the weakest feature of the game. Online multiplayer generally involved only un-upgraded planes, although each map featured a single upgraded craft that could be stolen.