Mount-based Quasi-Newtonian Propulsion (SEIV)
From SEWiki
The basic design principle of mQNP is that engines are scaled in size based on the size of the ship hull. The mQNP system was first proposed by Pax in a thread on Shrapnel Games Intel Forums.
To create a mQNP system, you need to choose a typical hull space to movement ratio. This ratio will determine how much space of the hull is used up by a single engine. Every ship hull will require a specific engine mount. In the sample system used, engines will provide 2 standard movement points and no bonus movement points. We shall use a 10% ratio.
Implementation
The first step is to calculate the hull space required for one engine for all hull sizes.
Hull Size kT for one engine 150 15 200 20 300 30 400 40 500 50 600 60 800 80 1000 100 1200 120 1500 150
Next, we must select a base engine size that will allow mounts to cover all ships. Since all ship hull sizes are factors of 50, all mounted engine sizes become factors of 5. We can make the base engine size become 5 kT on a 1% mount. This will allow engines to vary in 5 kT chunks, providing a fairly fine variation in the range of sizes possible. To achieve 5 kT on a 1% mount, the base engine must be 500 kT.
The next step is to calculate the scale factor for the mount for each ship hull. This is simply the kT for one engine value divided by the base engine size.
Hull Size kT for one engine Scale Factor 150 15 0.03 200 20 0.04 300 30 0.06 400 40 0.08 500 50 0.10 600 60 0.12 800 80 0.16 1000 100 0.20 1200 120 0.24 1500 150 0.30
Now, you are ready to create your mounts. Cost Percent, Tonnage Percent, Tonnage Structure Percent, Damage Percent, and Supply Percent should all scale with the size of the ship, probably by the same amounts.
The following tables summarize the hull space required to get various movement speeds for 4 ship hulls when using engines that provide 2 movement points:
Hull Size Speed 2 Speed 4 Speed 6 Speed 8 Speed 10 150 15 / 10% 30 / 20% 45 / 30% 60 / 40% 75 / 50% 200 20 / 10% 40 / 20% 60 / 30% 80 / 40% 100 / 50% 300 30 / 10% 60 / 20% 90 / 30% 120 / 40% 150 / 50% 400 40 / 10% 80 / 20% 120 / 30% 160 / 40% 200 / 50%
Note that the engine movement and hull ratio values used in this example were chosen to simplify the math. If you want a system with a finer gradation of movement (in 1 MP increments), you could have the engines provide 1 MP and use a 5% ratio. The same scale mounts can be used. This would provide the exact same speed values as in the above chart for the listed percentages of hull space used and greater flexibility in design.
Converting QNP to mQNP
An alternative method for creating a mQNP system is to start with a QNP system as the basis. The ModWorks QNP system was used as the basis. In this system, all ship hulls have an Engines Per Move setting equal to Tonnage / 50. Engines generate only standard movement points, based off of the following table:
Ion 3 Contra Terrane 4 Jacketed Photon 5 Quantum 6
The sample mQNP system used will have each engine provide 1 point of standard movement. Bonus movement will be set to 0.
The first step in setting up the mounts is to determine how much hull space is required for each engine type to provide 1 full movement point. We can use the following formula:
SPACE_FOR_ONE_STRATEGIC_MOVEMENT = 1 / ( QNP_STD_MOVE / ( HULL_TONNAGE / 50 ) ) * 10
QNP_STD_MOVE is the standard movement points given by the engine in the QNP system
HULL_TONNAGE is the size of the hull, naturally.
The 50 comes from the formula used to calculate the Engines Per Move values in the QNP system.
The 10 comes from the size of all engines in the QNP system being 10 kT.
You should perform this calculation for every combination of engine class and hull size. For this system, the following values are found:
Hull Size EPM ION Size CT Size JP Size Quantum Size 150 3 10 8 6 5 200 4 13 10 8 7 300 6 20 15 12 10 400 8 27 20 16 13 500 10 33 25 20 17 600 12 40 30 24 20 800 16 53 40 32 27 1000 20 67 50 40 33 1200 24 80 60 48 40 1500 30 100 75 60 50
Now, you need to calculate the percentage values you need for the scale mounts. A simple method is to make the size requirement of the engine on the largest ship class be the base size of each engine. In the example system, Ion Engines will be 100 kT, Contra-Terrane Engine will be 75 kT, Jacketed Photon Engines will be 60 kT, and Quantum Engines will be 50 kT. The size that engines need to be on smaller ships then becomes a simple percentage of the base size. The percent values used for the mounts in the example mod work out to be:
Hull Size Scale Factor 150 0.10 200 0.13 300 0.20 400 0.27 500 0.33 600 0.40 800 0.53 1000 0.67 1200 0.80 1500 1.00
If your mod has very large hull sizes in it, such as 15000 kT, you might run into problems. If you make the engines the size they would be on a 15000 kT ship hull, you lose all fine gradations of size on smaller ship hulls. In this system, engines would have to vary by 10 kT chunks, as the Ion Engine base size would need to be 1000 kT.
Any ship larger than 1500 kT will not fit with the QNP scale used so far. They require fewer and fewer percentage points of hull space to get 1 movement point. To remedy this, there are several solutions:
1) You can increase the base size of all engines by a certain factor. If you do this, you need to decrease the scale factors for each mount to keep the engines the same size on the smaller ships. I would not recommend going above about x5 with this method. With x5, you still get decent variation of engine sizes for the different hull sizes. Going much larger, you run into problems of different sized hulls requring the same number of engines, such as the 400 kT and 500 kT hulls.
2) Larger ship hulls could require multiple engines per move. In the example system, a 3000 kT ship would require 2 engines per move, a 4500 kT ship would require 3 engines per move, and so on.
3) If you have very different sized ships, ranging from say 150 to 30000, you can combine parts 1 and 2. If you go with a x5 factor, ships up to 7500 kT will use mounts. The 7500 kT ship will require no mount, as it uses the base engine size. Anything larger would require multiple engines. This system would not have much variation allowed in the larger hull sizes, as they would need to be fairly close to multiples of 7500 kT to maintain the base thrust ratio.
