Trying to find a constant or an equation

[Some text.]

I am programming a little spaceship game, and my quandry is as follows;

I want the ship's turning ability to be relative to it's speed.
Though the particular values of each have to fall within a specific range.

So for speed of 3.00 (max), i would like a turning rate of about 0.015
And for speed 0.5 or so, i want it to be around 0.028

So I am trying to organise an equation or two to produce these figures as a result of speed, as this is the driving force(Ranging from 0.0 to 3.0). A nice curve would be ideal, rather than a straight line.

Much thanks for any help, I am tired, can't code straight and can't find a way to crack this.

 

[Unrest]

Try by sketching a graph of what you want then think of functions that look like it.

Could be a-x² if you want nearly constant turning rate at low speed, then decreasing faster and faster with speed. Or inverse sin, inverse tan, sigmoid, etc. if you want the turning rate to plateau at both ends of the speed range.