SimplePlanes 2 | Propeller Engines

Our procedural powertrain system might seem like it’s just for cars, however it is anything but that. We are adding aircraft engines that can interact with powertrains in the same way the car engine can, using a brand new procedural propeller part you attach to the front (or to a driveshaft anywhere else!), and it all interconnects nicely to let you do just about whatever you want. You can power a car with an aircraft engine, or an aircraft with a car engine if you're so inclined. You can power multiple propellers with a single engine if you can connect it up with the proper driveshafts and powertrain parts. It’s all in your hands, and it’s something we’re really excited about.

The rest of the aircraft engine section of this post will be handled by Andrew:

The Engines

We are starting with three distinct procedural engine types to cover the most popular styles.

Flat Aircraft Engine

This is your bread and butter for general aviation. Compact, air-cooled, and lightweight, it’s perfect for small trainers or bush planes. It doesn't have the raw grunt of the bigger engines, but it fits where others won't and keeps your weight down.

Liquid Cooled V-Engine

If you want speed, this is where you start. Inspired by legends like the Merlin engine found in the P-51 Mustang, this engine is larger, heavier, and significantly more powerful.

Radial Engine

Big, heavy, and absolutely full of awesome. This is for when you want to move a lot of air and look good doing it. It might not be the most aerodynamic or efficient option, but it makes up for it in sheer style.

The customization here is impressive. You can stack cylinders to your heart's content. We’re talking up to 3 rows of 9 cylinders each. That is a 27-cylinder monster capable of putting out over 1,000 horsepower without a supercharger.

The New Propeller Assembly

An engine is only as good as the thing it spins. The Propeller Assembly has been completely rebuilt to keep up with the new physics system.

You still have all the customization you loved in SP1: blade count, diameter, blade width, and pitch. But we’ve added some new toys for the engineers among you. You can now adjust the Hub Scale for better visual integration with your spinners, and crucially, you can now adjust the Twist Angle.

Real propeller blades aren't flat; they twist from root to tip to ensure the angle of attack is efficient across the whole blade. Now, you can fine-tune that twist to optimize your prop for climbing, cruising, or speed.

Prop Physics

The new Propeller Assembly utilizes Blade Element Theory (BET) for its physics simulation. Instead of treating the propeller as a single disc, the game now breaks the blades down into multiple segments. It calculates the angle of attack, velocity, lift, and drag for each segment of the blade individually and sums them up.

If you pitch your blades too aggressively, you’ll feel the engine bog down and your RPM drop as the drag torque spikes. If you dive too fast with the throttle cut, you’ll see the prop windmill and actually add torque into the powertrain system.

It is a level of fidelity that simply wasn't possible in the first game, and when combined with the new procedural engines and powertrain, it makes flying feel more alive than ever.

Superchargers

Let's move back over to car engines for a sec. A common way to add extra performance to your engine in real life