Custom Ship Maneuverability

[cozy]

Hello...
I'm curious about how can I edit the maneuverability of my newly created ship...
It is a freighter design, but I wanna try to make its movement a bit more like a very heavy fighter instead of cargo type =]
But I can't find what and which value to edit to be able to do so...
Any help would be very appreciated...
Thx.

[Gibbon]

In the shiparch section, these entries affect handling,

steering_torque = 55000, 55000, 48000
angular_drag = 41000, 41000, 35000
rotation_inertia = 8400, 8400, 1000
nudge_force = 30000
strafe_force = 20000
strafe_power_usage = 2

Those are standard VHF settings.

[cozy]

err... gibb, can u explain how those number works?

[Gibbon]

You asked for it rofl, this is a rather long winded explanation by Startrader, who does actually know what he's talking about...

Well, I felt a break from my mod-troubleshooting was needed so I decided a Tutorial is a good one to take 'cos it may help some of youse out there!

This one discusses how to get your new ship to handle the way you want it without shooting too much in the dark. I try to explain why we do things, so it is a bit long, save a copy and maybe print it to keep it handy.

First you need to set a mass for your new ship that is in proportion to others of similar size.

For example if your new ship is the size and shape of a Titan then give it a mass of about 150-170. If it's the size of a Titan and almost cubic, then it should be more like 300. If it's a huge Borg Cube make it about 2,000,000 - 2,500,000. And so on.

In passing, some words of wisdom on cargo capacity:-

To be realistic give your ships a cargo capacity that relates to the ship's size and purpose, in the case of a Titan it really should NOT be more than 30 if you are considering the mass units as metric tonnes (1000 Kg each). I mean, look at the shape of the Titan - where would you put even 30 tonnes of cargo??!

Even if your ship is a Cube, I don't think it will be able to hold more than around 20,000 tonnes as the rest is taken up with ship components and weaponry if we apply "virtual intelligence" and architectural thought to this hypothesis.

Or you may decide to "cargo-size" your ships in units of 500 Kg or something else even - fine, as long as all ships are relatively cargo-sized according to their function, and reasonable. Freighters will of course be able to hold much more cargo per mass unit than similar-sized fighters or similar-sized warships. I use 0.2 x mass for fighters, 0.3 x mass for warships and 3.0 x mass for freighters. And I also modify these values for skinny or fat ships, ships with gaps in the body, and ships with lots of armour. But for goodness' sake don't give the Dromedary 3,000 cargo space!!

Next: Handling. Our main subject for today.

First, always ensure that your ship's type parameter is type = FIGHTER or type = FREIGHTER. Anything else (type = CAPITAL / CAPITOL / GUNSHIP / GUNBOAT / CRUISER) will make it roll in the opposite direction to its yaw no matter what you set in your handling parameters.

This means that when you turn left, it will roll to the right, not to the left. It may also roll over completely! Tally-Ho, Belly-Up! A new way to dog-fight, sure to fool the enemy! (into shooting you to oblivion while you try to decide which way is up and where he is!)! Heheheh.

Hrrrmmphh... back to the serious stuff...

FL uses different "mass/drag coefficients" for different sized ships, and sometimes for the Z axis of the same ship, to be able to make ships handle correctly, because some need more force to bank than others. And some bank very little or don't bank at all.

Typically ships with big vertical fins like the Titan may need less Z-axis force to bank than ships with small or no vertical fins like the Eagle. Bear this in mind too when looking at the shape of your ship, if you use too great a force for the Z-axis of a ship with big vertical fins, it may well bank too fast when turning, and this will give your crew space-lurgy!

OK - to get these coefficients, divide each of the axis angular_drag values by the ship's mass for a selection of standard FL ships, and round them up (or down, up to you) to the nearest 50 or the nearest 100, as you feel appropriate. We will use them to set the steering_torque, angular_drag and rotation_inertia values of your new ships with some intelligence and proportionalism.

For example, for my Starflier, mass = 75 and angular_drag = 19000, 19000, 34000

So my mass/drag coefficients for the Starflier are:-
X = 19000/75 = 253.333
Y = 19000/75 = 253.333
Z = 34000/75 = 453.333

and as it's a small ship I decided to round down to the nearest 50, so it becomes 250, 250, 450.

For the Osiris, its mass = 6200 and angular_drag = 13014000000, 13014000000, 13014000000

So my coefficents are:-
X = 13014000000/6200 = 173520000
Y = 173520000
Z = 173520000

No rounding is needed, and Z is the same as X and Y.

Why? Because the Osiris and other battleships bank slowly, and not very much when turning, so we don't need to apply much more force to bank than to turn or pitch. Some force is always needed of course, or the ship will roll in the opposite direction to the turn - just like in reality when you ride your bike and turn, you have to lean into the turn or you will fall off your bike as it tries to roll in the opposite direction (centripetal force, I think it is called - primary school physics, can't remember much about it!)

In passing, the maximum angle of bank for a ship is set by max_bank_angle = xx. Set this to whatever you want for your ship, I use 10 degrees for big 'uns, 30-45 for my fighters and heavy interceptors, and 60 for very agile light fighters.

OK, now you are properly informed and equipped to use the appropriate standard FL mass/drag coefficient for the size of your new ship.

Let's get down to the nitty-gritty!

1. Drag is the force that opposes any movement of an object through a fluid in a given direction. It can be resistance or friction with the fluid (liquid or gas, or perhaps another less-dense solid) that is surrounding the object. OK, we know space doesn't produce much friction or resistance, but we need to have some for our ship to slow down when we "lift the pedal from the medal"!

So we'll start by setting the drag for our new ship;
angular_drag = (ship's mass) x (mass/drag coefficient for a similar-sized standard ship).

For example; let's use a new light fighter similar in size to the starflier, but with mass = 80...
angular_drag = (80x250), (80x250), (80x450) = 20000, 20000, 36000 - EASY!

The next steps for steering_torque and rotational_inertia are now easy to work out, but need some thought...

2. Inertia is the force that opposes any attempt to change the current motionary status of an object. Try turning an elephant even when you place it on a platform that can turn in any direction - darn, he's still hard to get moving! But when he's moving, he will still be hard to stop too, because of the very same force! We need to set one up for our ship so it does the same.

We will set the ship's rotational_inertia values between 10% and 20% of its angular_drag for each of the 3 planes. Exceeding the lower limit will make your ship not be able to damp down when using Goto / Dock. Exceeding the higher one will make it spin like a top when hit by another ship.

So for our ship example let's set it at 15% to be on the safe side;
rotational_inertia = (20000x0.15), (20000x0.15), (36000x0.15) = 3000, 3000, 5400

3. Steering_Torque is the external force that will be applied to the ship to make it turn left/right, pitch up/down, or roll (bank) left/right.

OK - now we know it will be opposed by two other forces - inertia will resist change of motion, and drag will resist motion.

To set how your ship handles in turns in the 3 planes, set steering_torque = angular_drag x radians per second that you want your ship to turn in each plane.

For example if you set steering_torque to the same as angular_drag, then your turn rate will be 1 radian/sec (about 57 degrees per second). That's good for a very heavy fighter.

I set my big heavies to 0.2 radians per second, and they are sluggish - excellent for heavy haulers and really big battleships. Then other ships are in between 0.2 and 1.0, and light fighters can be good at up to 2.0 radians/sec (114 degrees/sec) - any higher and it gets silly.

So for a Heavy Fighter, try steering_torque = 1.2 x angular_drag for all 3 angular_drag values.

You can easily vary the handling of similar ships by increasing the steering_torque by 10% for more manoeuverable ones and decrease it by 10% for more sluggish ones.

For our example, we will set 2 radians per second in each plane;
steering_torque = 2 x 20000, 2 x 20000, 2 x 36000 = 40000, 40000, 72000 - Done!

What's left? Minor stuff.

For a starting point:-

4. Set your nudge_force (the force applied when your ship is trying to avoid asteroids when it's in cruise) to around 300 x the ship mass.

For our example ship, we get nudge_force = 300 x 80 = 24000

5. Set strafe_force (the force applied when you press the strafe-left, strafe-right, strafe-up and strafe-down keys) to 2 x nudge_force.

For our example, strafe_force = 2 x 24000 = 48000

6. Set strafe_power_usage to whatever you want, much bigger for bigger ships than for smaller ships - after all if it doesn't use power it's unreal. I use 500 for really big heavies and proportionally less for smaller ships, down to 20 for starflier-sized ones. Then I can watch my power run down as I press the strafe keys, feels good! )

If your ship already has an engine assigned then that is it! Go test it in space and make any tinkering adjustments you want, to make it individual and not just another Starflier. It's good to go.

If some aspect of handling doesn't feel right, reduce or increase the mass/drag coefficient and try again until you like it.

Now - these are my views from my own long hours of experimenting, and will give you starting points so that you can understand how these settings interact, but of course yours can be different.

Try and see. If you don't like what you get, you should now be able to decide what you should change to get what you want. Be a real test-pilot!