New physics are coming to Liftoff and this blogpost tells you all about it!
The previous update of the Experimental Branch brought a lot of changes to the physics of Liftoff. We were glad to see the Liftoff players enjoyed these updates and we feel the project has been in a really good state ever since. Nonetheless, we’ve always felt we could do even better and that’s what Liftoff Physics 3.0 is all about!
Based on lots of experimental wind tunnel data, we developed a whole new set of physical models that should be a lot more realistic. The main differences in terms of flight behaviour should be the following:
- Quads should now fall faster when throttle is cut.
- Quads controls should now feel more responsive, and a bit snappier.
- The cornering behaviour is improved. Thrust can be used more efficiently to control the quad’s trajectory.
- If you use a low camera angle (between 0° and 45°), you should experience a downforce when racing and cutting throttle. If you use a higher camera angle, you will feel a strong deceleration and/or a downward push in same circumstances.
- All parts were re-balanced and are more realistic. As a result, all the possible builds are more different from each other than ever, and result in very different flight behaviour.
- Battery Draining is slower and closer to reality.
- Weight is now as important as in real-life, and so is thrust-to-weight ratio. High ratio will make your build powerful and very controllable in curves, and lower ratios will bring more “driftiness” to your flight.
Detailed list of changes
- Max RPM
Max RPM is now calculated with a new physical model. It now also takes into account the number of blades of a propeller and should give results a lot closer to reality.
- Static Thrust
Static thrust is the thrust that would be produced by a motor and a propeller at max RPM, assuming zero airspeed. It is a theoretical value that represents the highest thrust that could be attained in specific circumstances. Static thrust now uses a new model. Its scaling with part characteristics is much closer to reality. Static thrust is now lower than the current one used in the game.
- Dynamic Thrust
Dynamic thrust might be the area where most changes happened. Dynamic thrust is the real thrust that is available to your quad. It decreases with airspeed until a certain speed at which the quad can’t generate any thrust. That phenomenon was not taken into account before. We use a new model to calculate the speed at which you no longer generate thrust, based on the motor, the propeller and the rotation speed of the motors. Also, beyond that speed propellers can now generate negative thrust, which also happens in reality. The most obvious consequence of this phenomenon is that sometimes when you race and suddenly cut the throttle, you might feel a downward push on your quad, or in more extreme cases, when flying at a high angle, a major deceleration. In the same way, if the speed of the air coming to the motors is negative, like in a sharp turn or when the quad is falling horizontally, the dynamic thrust generated can exceed static thrust for a short time, just like in real life.
- Battery draining
Before this update, Liftoff had a tendency to drain batteries too fast in certain conditions. We are now using a new model that is closer to experimental data available.
Our drag model now scales better with the size of the quad and drag should be lower in general. We now calculate individual drag for each surface of the quadcopter, making it more realistic. We expect the quad to fall a little faster and to have some “driftiness”, allowing the pilot to use throttle to adjust and find the perfect trajectory. That “driftiness” can be increased by adding weight to the build through the workbench.
- Balance of the parts
Manufacturer datasheets are often the result of calculations and don’t necessarily reflect reality. We have scaled some of the part characteristics in order to reach the thrust level observed in experimental wind tunnel data from reliable third-party testers. We are also actively working on new, often requested parts, such as high-performances batteries, and lower Kv motor to use with 6S batteries.
The effect of weight is now more important. The heavier a drone, the more momentum will be carried in turns or when throttle is suddenly cut. You can still add weight to your builds in the workbench, to tune them to your preferences.
- Game engine physics
We don’t use any of the game engine physics functions anymore and developed our own instead. This way, we have a better control over the simulation code.
When and how?
We hope to include these new physics changes in our V1 release (around Gamescom). In order for that to happen, we’ll need a lot of test results from the community.
We’ve been testing the Liftoff Physics 3.0 for a while behind the scenes and we’ll be making them available to you in the next few days. We’ll be sharing the information required to access a branch as soon as it is available! Make sure to check our official channels.
Reaching our V1 goals will only be possible with your help, so we are counting on your support. Thanks in advance!
Liftoff will have the best sim physics ever!