Customizable Platform Drag

After Factorio Space Age version 2.1.21

With the newest update Wube finally changed their algorithm to stop relying on platform width. However, the new expression has some quirks of its own. Now to define the condition for top speed it can be roughly expressed like:
thrust = (1,2984 * speed² * weight ^ 0.8 + 10,000) * (1 + weight / 10,000,000)
It surely does depend on weight, but having the exponent be smaller than 1 means some particular shape of ship for every weight gets maximum speed bonus. To avoid confusion and unintuitive mechanics I kept the stock settings version of the expression as:
thrust = (0.06 * speed² * weight ^ 1.0 + 10,000) * (1 + weight / 10,000,000)
That exact coefficient was calculated before the update by linking every 8 platform width tiles to 100 tons of mass. As the relation is linear, a smaller ship is always faster for the same thrust to weight ratio. But if you don't want the stock thrust penalty for extremely heavy ships to matter at all, you can set the Weight Penalty to the highest value.

I also simplified and streamlined the final calculation so you should be aware that you might need very different Deceleration Coefficient valsues to make it playable and balanced depending on what parameter you are relying on. I left relevant example values in the settings description so you can make it work like the stock game before 2.1.21 or how stock works now.

The comparison with Legacy Platform Drag

My mod can be made to work essentially the same if you select the needed values. But that one is simpler as it's straightforward.

Before Factorio Space Age version 2.1.21

The stock Space Age acceleration formula can be roughly converted to this to define the condition for top speed:
thrust = (750 * speed² * width + 10,000) * (1 + weight / 10,000,000)
It applies several drag forces to moving spaceships. Main component is the square of speed. Secondary one is directly proportional to the platform's width. And the last, tertiary part is vaguely connected to weight. Realistically, the last part only starts to affect your ship when it's breaking multiple thousands tons in mass. This formula works but also means that making you ship long barely affects its top speed. And the width directly correlates to the number of engines you can place. Together both mean that you can make all your ships as large as you want while maintaining top speed. What I wanted to see is the utility of small ships in your fleet. Light = fast is my thought. Large ships can still be your dreadnoughts and haulers, but if you want to be somewhere fast, you should try to miniaturize.

tldr:

You install it and your heavy ships become slower regardless of shape.

What the mod settings do

You can choose what components you want in you game by defining the Power for each component. Exponent of 1 means it's proportional, 2 is quadratic and 0 means this parameter won't affect your ships at all. You can use decimal numbers too. The Deceleration Coefficient lets you choose how strong is the combined drag force. Speed Penalty is also a phantom force that can help you to reach the nearest planet without thrust. In the context of this mod, every 8 platform width tiles are equal to 100 tons.

Stock setting just changes reliance on width to the weight component in a balanced manner.
Setting Speed Power to proportional means the speed cap becomes much less hard, and you can speed up easily, be cautious!
Changing Deceleration Coefficient and Speed Penalty to 0 means your ships will no longer slow down at all. Do you want real space?
Changing Inertia Coefficient and Weight Inertia Power allows you to manipulate time. It's fun, try it!

The difference with Simpler Platform Drag

My problem with the other Platform Drag mod, other than the lack of settings, was that it doesn't do what it says. What it accomplishes is making all platforms with the same shape have the same theoretical top speed. It doesn't penalize ship's mass itself and instead punishes proportionally long platforms. The side effect of this is a buff to wide platforms. In fact, you can make your ships faster just by copying them side by side and merging together. But it does keep the speed of square platforms the same as in stock so if that's what you want you can use that mod instead.

If you have any suggestions about the balance or want to show off your ships of different size, link me your saves for testing!