Copyright Frontier Developments Ltd
WARNING
- NOT FOR THE TECHNICALLY FAINT HEARTED!
(You do not need to read this to fly your ship)
As starship designers through the ages have found, space craft have so many potential degrees of freedom they are impractical for a mere human to control to the full unaided. Logically a free flying combat craft has at least five independent directions (or vectors) to control. Those vectors are:
(1). Facing vector (unit magnitude) F
(2). Velocity vector V
(3). Thrust vector T
(4). Camera viewing vector C
(5). Weapon vector W
It is clearly logical to combine some of these, but the more they are combined, the more functionality is lost. Faulcon de Lacy (and indeed most ship manufacturers) combine (1), (4) and (5) and control (2) and (3) automatically, leaving the pilot to control only (1), with the option of disabling the automatic control of (2) and (3) when necessary. Even this seems a handful for a species evolved to move in only two and a half dimensions (up and down are very much secondary to north, south, east and west).
The pilot is assumed to have a desired velocity vector D along his or her facing vector, the magnitude of which is the desired speed s they have set.
Hence: D=sF
& thrust to achieve vel. D T=mf(D-V)
where f is a factor chosen for fuel efficiency.
and m is the mass of your craft
A maximum value is given to f (about 1), to avoid wasteful thrusting and possible oscillations. This is why your craft will slowly settle down over the landing pad even with a zero set speed. At higher speeds the limits of the power of the thrusters effectively restrict the value of f. The desired thrust is resolved into components along each of the ships working thrusters and if any of the these cannot provide sufficient thrust then the value of f is reduced appropriately (preserving the direction of thrust is more important than its magnitude).
The problems of the fly-by-wire technique are further complicated when considering the frames of reference in which velocities are measured. When a vehicle moves slowly along a street, say, the driver does not want to know that both the street and the vehicle are moving sideways at many thousands of kilometers per hour (due to the velocity of the planet around the star, and the rotation of the planet). Indeed, if the vehicle were to face the way it is travelling, then its motion along the road would be almost irrelevant. What the driver wants is to face along the direction of travel in the frame of reference of the planet, which is both moving and rotating.
Hence: D=sF+R where R is the velocity of the frame of reference
and ideal thrust T=mf(D-V)
T=mf(sF+R-V)
Your onboard computer automatically selects the body you are most likely to want to define a frame of reference for your motion. This is usually a planet or moon, but can also be a space station or large ship. It also decides whether it would be more intuitive to use a rotating frame or not. For space stations, it is only sensible to use a rotating frame in the docking tunnel - otherwise your ship continually thrusts to attempt to move in a circle in time with a similar point on the station.
The body used to define your current frame of reference is shown on the bottom right of your head-up display. This is chosen by a weighting function. For planets and stars, this is based on mass, thus a star's sphere of influence generally extends way beyond its planets. For other bodies it is based on their dimensions.
You may well notice your ship's engines suddenly starting to thrust when a different frame of reference is chosen. This is not a fault with your ship but is because your set speed has suddenly appeared to change as it is now measured relative to the new body.