Monthly Archive: September 2017

Better physics for missiles

We've recently taken a break from graphics and UI avionics rendering, to focus on physics. More specifically on aerodynamics.

Sample image or an AGM-65 gliding to hit a tank

This came about as missiles needed and improvement on hit precision.
A game can cheat at will and always make a missile hit a target, however the effect is not pleasing and the strategic element goes away, as behavior is no longer tied to laws of nature, making the experience less believable.

A missile's ability to hit a target is determined by its capacity to individuate and seek a target, but also by the raw performance of its rocket motor and its air frame, or body.
Air-to-ground/surface (AG or AS) missiles don't necessarily have enough rocket fuel to reach a target, and may often end up reaching the target while gliding, much like a smart bomb.

For this reason we decided that improving the aerodynamic simulation was important to simulate the nuances of hitting a target, with realistic weapons with realistic physical parameters that give them specific advantages and disadvantages.

We're currently working with a few real-world references, so to have a rough idea of what kind of rocket motor and air frame should correspond to a certain performance range.

AGM-65 airframe debug view

Here's a wire-frame debug screenshot of a model of a Maverick AGM-65 in our game (graphics are in pure simulation mode, not representative of the actual game graphics).

Blue areas are the definition of the wings.
Magenta lines represent the drag force (Fd).
Cyan lines represent the lift force (Fl).
The smaller green box represents center of gravity (CG).

Much more work is necessary, but it's already exciting to see a missile fly using the proper laws of physics, although this has complicated things a fair bit.


At this point, the aerodynamics of the actual airplane is less advanced than that for the missiles, but in time, the improved model will be transferred to the plane as well... although with jet fighters is not that simple, but this is a topic for another post...

Check out NASA's friendly explanation on the major 4 forces acting on an airplane, or a missile.