Have you wondered why you are getting poor thruster efficiency? Or why your ship doesn't fly/strafe straight? This thread will make sense of it all!
If you are a SSC enthusiast like I am who frequently lurks around the ship-designer channel on discord, you will notice that many people have come up with many theories regarding how MFC behaves and what it does or doesn't do in order to make your ship behave normally when responding to basic flight commands such as forward, backward, roll, pitch and so on. Some even say "don't try to reason with MFC", or "don't use logic with MFC", because many of MFC's behaviours simply don't make any sense. I myself have held this opinion for a very long time until recently when I discovered what may ultimately be THE THEORY that is able to explain every weird behaviour from bad strafe/pitch/yaw to poor thruster efficiency and much more.
Before we dive in - we are making an assumption that your ship is constructed without errors - and by that I mean, no thrusters blocked, all thrusters are connected and have proper access to both propellant and electricity, FCU has the correct orientation, and levers properly named, the list goes on and you get the idea. If your ship has any of those problems, fix those first.
To begin, I will explain some terminologies in the title and this also serves the purpose of being an introduction to the basic concepts that will lead to the theory itself later on in the thread.
Thruster Efficiency:
We all have access to the wiki pages that tell you how much thrust each type of thruster can produce, but how much thrust your MFC decides to use is almost always lower. To find out how much thrust your thrusters are producing is quite simple, point your U tool at a thruster, the second devicefield will be a number anywhere between 0-10000. If you are going 100% full throttle, you can point your U tool at all your rear facing thrusters, if most of your thrusters are around 9000, your thruster efficiency is about 90%. To optimise your forward thrust, you want this number to be as close to 10000 as possible.
Shameless plug of my previous thread that details what lead me into discovering both minimum thrust and thruster precision:
https://forum.starbasegame.com/thre...c-strafe-issues-my-journey-through-hell.2789/
Minimum Thrust:
If you have read my previous thread (link is above), you will see how I discovered that there is a minimum thrust that a thruster must produce if it's producing any thrust at all.
Thruster Precision:
Yes, thrusters also have limited precision. If we assume that both minimum thrust and thruster precision is exactly 1 (since ThrusterCurrentThrust is always an integer between 0 and 10000), consider what this also means - the lowest thrust your thruster can produce is exactly 0.01% of your maximum thrust, this translates to 55 units of thrust for a T2 box thruster, and 33 units of thrust for a T2 triangle thruster, and that a T2 box thruster will always produce multiples of 55 units of thrust (55, 110, 165, and so on). The actual multiplier may very well be something above 1 and we won't know it until we have access to the math behind the scenes. This also means that the more thrusters you group into a single group, the higher your minimum thrust is, and the less accurate your thrusters become. If you have 10 T2 triangle thrusters stacked in a single group, their minimum thrust becomes 330 assuming the minimum ThrusterCurrentThrust is 1, and that triangle thruster array can only produce thrust in 330 increments up to 3,300,000.
Centre of Mass and Angular Inertia - literally rocket science!
This will actually take some background in physics and mathematics to understand. I won't go into much detail here because frankly it's been too many years since I've studied these in high school that I can't really explain them very well. You are better off looking up some educational materials on your own.
The important takeaway here is that - when we are considering the effect a thruster has on your ship's heading, the further away a thruster is from your centre of mass, the more impact it will have on your heading. Example:
In this example, whilst both thruster A and B will cause the ship to have the tendency to yaw to the right, thruster A will have a much smaller impact on the ship's heading than thruster B.
Here is when this gets good.
Why is this important you ask? How do these tie together?
Consider both thruster A and thruster B, since both of them have limited precision (only in increments of 55 units of thrust), thruster A will allow MUCH FINER control by your MFC on your ship's heading than thruster B since it has much less impact on your ship's heading!
This means that, when we are organising our thruster groups, the most optimal way is to setup in such a way that you are giving your MFC the finest control possible. Meaning, it's much more ideal to have thruster A to be a stand alone thruster group than to group it up with other thrusters and reduce your accuracy.
Real example on my own ship:
The setup above results in about ~90% thruster efficiency.
The setup above results in 99% thruster efficiency. That's 10% more thrust by just changing the grouping of these thrusters.
The reason why this is the case is, when the MFC cannot find a simple way to adjust your thrusters to maintain a stable heading, it'll try to play around with all available thruster groups and find a configuration that will keep your ship's heading stable. The finer control your MFC has, the less it has to do this, and the more efficient your thrusters become!
Common Misconceptions Regarding MFC:
I've grouped up more thrusters together and now I'm observing higher efficiency.
- No, what actually happened is that you've grouped up enough thrusters and the accuracy has become so bad that MFC cannot use those thrusters to precisely balance your ship anymore. There will be some edge crate-loading cases that causes you to not fly straight if you don't also have some other thrusters that allows very precise controls! You CAN get around this by prioritising your crates, but c'mon what's the fun in that!
MFC is dumb because it's firing my reverse thrusters to keep my heading straight.
- No, what's actually happening is that, the configuration of your forward thrust does not have enough accuracy to allow your MFC to keep your ship's heading straight. So it tries to fire reverse thrusters to achieve finer control.
Why can't MFC use my manoeuvre thrusers to keep my heading straight instead? I NEED SPEED!
- No because your side thrusters also have accuracy limitations! And they also tend to have way more drastic effects on your ship's heading than your rear main thrusters due to their position relative to your centre of mass. If firing your manoeuvre thruser to its minimum thrust will result in a change greater than needed, then MFC won't use it of course.
How do you explain that when I take off a tiny piece of floor mat, I gained/lost 10% thruster efficiency?!
- This is again, because your thruster setup does not allow fine control on your heading. So your MFC tries to play around with all available thruster groups and find a configuration that will keep you straight. As soon as you give your MFC precise control over your ship's heading, your thruster efficiency will become way more predictable
Why can't my ship strafe/pitch/yaw/roll correctly but everything is setup correctly?
- Because your manoeuvre thrusters don't have enough accuracy. They are either too far away from your centre of mass, or multiples grouped together that's reducing their precision. If MFC can't find a configuration to achieve the desired output, then it'll have problems. Try moving your manoeuvre thrusters closer to the centre of mass and ungroup them.
Here we go, this concludes my theory regarding MFC. Feedbacks welcome! Please feel free to prove me wrong.
If you are a SSC enthusiast like I am who frequently lurks around the ship-designer channel on discord, you will notice that many people have come up with many theories regarding how MFC behaves and what it does or doesn't do in order to make your ship behave normally when responding to basic flight commands such as forward, backward, roll, pitch and so on. Some even say "don't try to reason with MFC", or "don't use logic with MFC", because many of MFC's behaviours simply don't make any sense. I myself have held this opinion for a very long time until recently when I discovered what may ultimately be THE THEORY that is able to explain every weird behaviour from bad strafe/pitch/yaw to poor thruster efficiency and much more.
Before we dive in - we are making an assumption that your ship is constructed without errors - and by that I mean, no thrusters blocked, all thrusters are connected and have proper access to both propellant and electricity, FCU has the correct orientation, and levers properly named, the list goes on and you get the idea. If your ship has any of those problems, fix those first.
To begin, I will explain some terminologies in the title and this also serves the purpose of being an introduction to the basic concepts that will lead to the theory itself later on in the thread.
Thruster Efficiency:
We all have access to the wiki pages that tell you how much thrust each type of thruster can produce, but how much thrust your MFC decides to use is almost always lower. To find out how much thrust your thrusters are producing is quite simple, point your U tool at a thruster, the second devicefield will be a number anywhere between 0-10000. If you are going 100% full throttle, you can point your U tool at all your rear facing thrusters, if most of your thrusters are around 9000, your thruster efficiency is about 90%. To optimise your forward thrust, you want this number to be as close to 10000 as possible.
Shameless plug of my previous thread that details what lead me into discovering both minimum thrust and thruster precision:
https://forum.starbasegame.com/thre...c-strafe-issues-my-journey-through-hell.2789/
Minimum Thrust:
If you have read my previous thread (link is above), you will see how I discovered that there is a minimum thrust that a thruster must produce if it's producing any thrust at all.
Thruster Precision:
Yes, thrusters also have limited precision. If we assume that both minimum thrust and thruster precision is exactly 1 (since ThrusterCurrentThrust is always an integer between 0 and 10000), consider what this also means - the lowest thrust your thruster can produce is exactly 0.01% of your maximum thrust, this translates to 55 units of thrust for a T2 box thruster, and 33 units of thrust for a T2 triangle thruster, and that a T2 box thruster will always produce multiples of 55 units of thrust (55, 110, 165, and so on). The actual multiplier may very well be something above 1 and we won't know it until we have access to the math behind the scenes. This also means that the more thrusters you group into a single group, the higher your minimum thrust is, and the less accurate your thrusters become. If you have 10 T2 triangle thrusters stacked in a single group, their minimum thrust becomes 330 assuming the minimum ThrusterCurrentThrust is 1, and that triangle thruster array can only produce thrust in 330 increments up to 3,300,000.
Centre of Mass and Angular Inertia - literally rocket science!
This will actually take some background in physics and mathematics to understand. I won't go into much detail here because frankly it's been too many years since I've studied these in high school that I can't really explain them very well. You are better off looking up some educational materials on your own.
The important takeaway here is that - when we are considering the effect a thruster has on your ship's heading, the further away a thruster is from your centre of mass, the more impact it will have on your heading. Example:
In this example, whilst both thruster A and B will cause the ship to have the tendency to yaw to the right, thruster A will have a much smaller impact on the ship's heading than thruster B.
Here is when this gets good.
Why is this important you ask? How do these tie together?
Consider both thruster A and thruster B, since both of them have limited precision (only in increments of 55 units of thrust), thruster A will allow MUCH FINER control by your MFC on your ship's heading than thruster B since it has much less impact on your ship's heading!
This means that, when we are organising our thruster groups, the most optimal way is to setup in such a way that you are giving your MFC the finest control possible. Meaning, it's much more ideal to have thruster A to be a stand alone thruster group than to group it up with other thrusters and reduce your accuracy.
Real example on my own ship:
The setup above results in about ~90% thruster efficiency.
The setup above results in 99% thruster efficiency. That's 10% more thrust by just changing the grouping of these thrusters.
The reason why this is the case is, when the MFC cannot find a simple way to adjust your thrusters to maintain a stable heading, it'll try to play around with all available thruster groups and find a configuration that will keep your ship's heading stable. The finer control your MFC has, the less it has to do this, and the more efficient your thrusters become!
Common Misconceptions Regarding MFC:
I've grouped up more thrusters together and now I'm observing higher efficiency.
- No, what actually happened is that you've grouped up enough thrusters and the accuracy has become so bad that MFC cannot use those thrusters to precisely balance your ship anymore. There will be some edge crate-loading cases that causes you to not fly straight if you don't also have some other thrusters that allows very precise controls! You CAN get around this by prioritising your crates, but c'mon what's the fun in that!
MFC is dumb because it's firing my reverse thrusters to keep my heading straight.
- No, what's actually happening is that, the configuration of your forward thrust does not have enough accuracy to allow your MFC to keep your ship's heading straight. So it tries to fire reverse thrusters to achieve finer control.
Why can't MFC use my manoeuvre thrusers to keep my heading straight instead? I NEED SPEED!
- No because your side thrusters also have accuracy limitations! And they also tend to have way more drastic effects on your ship's heading than your rear main thrusters due to their position relative to your centre of mass. If firing your manoeuvre thruser to its minimum thrust will result in a change greater than needed, then MFC won't use it of course.
How do you explain that when I take off a tiny piece of floor mat, I gained/lost 10% thruster efficiency?!
- This is again, because your thruster setup does not allow fine control on your heading. So your MFC tries to play around with all available thruster groups and find a configuration that will keep you straight. As soon as you give your MFC precise control over your ship's heading, your thruster efficiency will become way more predictable
Why can't my ship strafe/pitch/yaw/roll correctly but everything is setup correctly?
- Because your manoeuvre thrusters don't have enough accuracy. They are either too far away from your centre of mass, or multiples grouped together that's reducing their precision. If MFC can't find a configuration to achieve the desired output, then it'll have problems. Try moving your manoeuvre thrusters closer to the centre of mass and ungroup them.
Here we go, this concludes my theory regarding MFC. Feedbacks welcome! Please feel free to prove me wrong.
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