[GUIDE] Building with the current Flight Model

BUILDING WITH THE CURRENT FLIGHT MODEL​

There still seems to be a lot of confusion going around about how the current flight model brought in with A11 works relative to the old one. Well i'm here to help clarify how these mechanics work and how they'll affect your build.

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RCS​

Previously, RCS were responsible for your ship's turning speed and roll. With the new mechanics these are no longer necessary, or at least only required in a supporting role.
Never again will you need 20+ RCS to turn your SVs! Gone are the days where a heavy RCS wall would take up 80% of your ships' internal space and 60% of your mass. You can fill this space with an actual interior, a warp drive, extra fuel tanks, more cargo or just extra armor.
RCS were and still are obscenely heavy and by removing them your ships become lighter and cheaper. Allowing you to turn with less force and keep your ship in the air with less thrusters.

If you have the CPU system enabled: RCS are also costly and by removing them you save tens of thousands of CPU points better spent on thrusters or weapons.
For every RCS you remove, you can replace them with 8 thrusters for the same CPU cost. Positioned correctly, those 8 thruster can provide more torque than the RCS could with the bonus of adding extra thrust in a given direction.

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Mass Effect​

The location and strength of your thrusters now affects how fast your ships turn. The effectiveness is determined by the distance on each axis your thrusters are placed relative to the ship's Center of Mass.
That sounds complicated, but it's actually very simple.
Basically: The further away your thrusters are from the big heavy middle of your ship, the faster your ship will turn.

You can see your ships' Center of Mass by opening the Build Menu (N), Going to the Debug Tab and enabling Center of Mass view. It's right there with Oxygen, Structural Integrity and Airtightness views.
The Yellow Ball is your ship's Center of Mass and the Blue Ball is the center of your ship's bounding box. They don't need to be on top of each other. Just as long as they're not way off to the left or right.

You'll notice there's also colored lines sticking out of the yellow ball that are the X, Y and Z axis of your ship and help show you where your roll, pitch and yaw are being applied around.

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Positioning Thrusters​

The further your thrusters are from the center of mass, the faster you will be able to turn. But there are limitations on which thrusters can affect which kind of turning.

• Side Thrusters adjust Yaw the further back/forward they are from the Center of Mass.
• Side Thrusters adjust Roll the further up/down they are from Center of Mass.
• Vertical Thrusters adjust Pitch the further back/forward they are from the Center of Mass.
• Vertical Thrusters adjust Roll the further left/right they are from the Center of Mass.
• Front/Back Thrusters adjust Yaw the further left/right they are from the Center of Mass.
• Front/Back Thrusters adjust Pitch the further up/down they are from the Center of Mass.
  
  
• Front/Back Thrusters cannot affect Roll
• Side Thrusters cannot affect Pitch
• Vertical Thrusters cannot affect Yaw

Yaw: Your ship's ability to turn left and right.
Pitch: Your ship's ability to pull up and down.
Roll: Your ship's ability to roll left and right.


Here's an example image of the UCH Rapier
The center of mass is almost perfectly aligned with the center of the ship.
Green lines indicate which thrusters are affecting YAW
Red lines indicate which thrusters are affecting PITCH
Blue lines indicate which thrusters are affecting ROLL

This ship doesn't roll particularly well since the thrusters for rolling are quite close to the center of mass line around which the ship rolls (Blue line)
These same thrusters are also barely affecting pitch, since they're centermass instead of far back or forward from the Center of Mass.
As a result of this design, RCS are needed to compensate to give faster roll and pitch.
Alternatively, the thrusters could be moved further back or forward, or to the ends of the wings for more mobility at the cost of design (It wouldn't look good).

Meanwhile, it has good yaw since the side thrusters are positioned forward and back from the center of mass and the main drive and reverse thrusters are seperated down each side of the center line.
The vertical thrusters on top also provide some pitch control, with the rear vertical thrusters providing excellent pitch for pulling up, while the single thruster behind the cockpit provides less thrust pulling down.

The best way to visualize rotation is to think of the Center of Mass as a pivot point or pin through the center of your ship; and you're applying pressure to each thruster like the ship's a pinwheel.
The further a thruster is from that pivot point, the easier it is for you to push it in a circle.

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Extra Considerations​

Overthrust
Overthrust is very common in carrier and cargo ships that are EMPTY. These ships are built to lift heavy loads and while they're not carrying heavy loads, all the thrusters that are there to lift heavy weights also go into pitch and roll. Without the weight to resist them, they'll be hypersensitive to player controls.
There are now sliders in the Statistics page of your ship's control panel that allow you to turn torque on each axis down. They do not allow you to turn torque up by taking away from another.

Similarly, using too many thrusters too far away from the center of mass can have the same effect. Where your ship will turn too fast and be completely uncontrollable. This is especially problematic with the big Jet Thrusters that now have so much thrust that using them for torque anywhere on your ship that's not center-mass will result in instantaneous rotation at a speed that no human can control. You won't be able to aim or fly your ship.
If there were G-Force effects on the pilot, you'd be smooshed into red paste in your cockpit if you tried to turn with that amount of thruster torque. Fortunately, there isn't... yet.
Place and balance your thrusters according to the speed you need them to fit. Use weaker or less thrusters if the strength is too much for you to control. Alternatively, add a switch to the Control Panel that turns off specific thrusters to cut torque down to managable levels.

Cargo Mass
With Mass and Volume enabled, your cargo also need balancing as the heavier your ship's storage containers are, the more it will shift your center of mass towards them.
Cargo Controllers+Extenders on one side of your ship will move the CoM towards them reducing your ship's yaw and roll in that direction and boosting it in the opposite. While centering the cargo mass towards the back of your ship will boost the effectiveness of thrusters' yaw and pitch near the front.

A good example of this effect being used positively is the Raider Technical prefab, that as the cargo storage in the back gets heavier, it will turn easier as the Center of Mass moves further away from the side thrusters near the front. Which makes it possible to have a ship that turns faster while carrying cargo, than it does while empty.

Asymmetrical Thruster Balancing
With the right design, you don't need to balance your thrusters between the front and the back to keep the Center of Mass at the center of your ship. You can put thrusters just at the rear (or front) of your ship and put cargo and other heavy devices at the opposite end. With the CoM moved forwards by the heavier devices, the rear thruster arrays can provide high torque while being protected at the rear.
This is dependant on the type and mass of the thrusters being used as the mass varies significantly between each thruster.

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Lift​

Lift is a value on all ships. The wider a ship's underside is, the higher its lift. With lift you can keep your ship in the air on planets with an atmosphere using less thrusters, or none at all with the right design.
As long as you have forward movement, even with terrible lift, a ship will stay more or less in the air; or at least longer than it used to.
Wings aren't necessary to get lift, regular armor blocks or carbon composite "flaps" will generate just as much lift as SV wings of the same dimensions.
Lift values are determined by atmospheric density. No atmospheric density and you'll drop like a rock (e.g. on a moon); too much density and you'll never come down.

Using lift coupled with an RCS or two, you can create ships propelled by thrusters on only 1 side that handle like an aircraft. You'll be able to turn and roll thanks to the RCS and drag will let you stop and slow down. With good enough lift, you'll only need to pulse the thrusters a couple of times a minute to stay in the air consuming virtually no fuel.
However, lift will also counteract vertical thrust if you're trying to land or take off. So keep in mind that if you're gearing to use lift to keep your ships in the air, you'll have trouble trying to land with VTOL thrusters as the surface area of your wings counteracts your thrusters.
If you have a large-winged aircraft, it lands like an aircraft. Not like a helicopter.

Lift is not restricted to just lightweight SVs, you can make a lift-based CV (See the Forge Skyfortress prefab) that can navigate a planet on minimal power that's ideal for anti-ground combat since it can divert more CPU to weapons and shields since it needs less thrusters.

This is the Altostratus (not the skyfortress). A CV bomber with a wingspan of 113 meters. The wings are mostly carbon composite with a bit of steel on the front edge. The amount of lift this CV has is so massive that with a single pulse of the thrusters it can stay airborne for 2 minutes with vertical thrusters turned off.
Just so you know what can be done with the right configuration.

Note: Lift is not applied correctly while upside-down. If you try to roll a lift-based ship it will drop like a rock once it's completely inverted.

Drag​

No, not like your uncle on a friday night. Drag is like the opposite of lift in Empyrion. It's determined based on your ship's cross-section against the direction of movement and it slows down your ship relative to atmospheric density.
So if you're travelling forwards, it'll be the blocks that make up the "face" of your ship that determine your drag. So a big square, fat/tall ship will be slowed more by atmosphere than one thin, angled ship.
If you're dropping straight down, it'll be underside of your ship. A big ship with wingspan will drop slower than one without and not just because of lift, but because of drag as well.

Additionally, block shape also affects drag. Angled blocks produce less drag than a solid block face (slope vs cube), so those thin tapered edged ship hulls are good for something beyond looking fancy. Noobcubes are bad.
More drag means you need more thrust to counteract it, so your ship will move slower and stop quicker when you stop thrusting. Basically, flying a brick on a planet will kill your fuel supply faster and reduce your top speed.

Note: Both lift and drag are simplified in Empyrion. Air density doesn't change depending on height, wings don't let you turn faster (yet) and weather doesn't affect handling (yet).
Ideally, a ship will be a flat triangular shape like a normal Aircraft, Jet Fighter or X-Wing since it has low drag and high lift with ideal positioning for thrusters for maximum torque. Keeping vital equipment at the back and perfect for hit-and-run tactics against a ground installation.

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- End Transmission -​

 

Great info Vermillion. Helps me when I eventually create my own SV and CV ships.

 

Any idea if there's an advantage to having balanced thrust in a given vector? Like, say I had a craft with two thrusters propelling me forward. If I place them low on the airframe, they can help the craft quickly pitch up to climb if I have to evade. Except, this placement seems to mean the ship would always being trying to pitch up, and the other thrusters would have to fire to compensate, making the layout less efficient in level flight. On the other hand, if I had perfectly placed one thruster above and one below the center of mass to balance each other, any torque they generate would cancel each other out.

Is the simulation extensive enough for this kind of problem to happen?

 

That won't be a problem. You'll have faster turning while pitching up, but you won't pitch up on your own.

 

This was very useful and clearly explained. Thanks!

 

Necro bump: Still very relevant and excellent information laid out here. Thanks for the work put into this, Vermillion!

 

Grateful, most excellent Discussion thank you. Rise from the Grave!