A propfan, also called an open rotor engine, or unducted fan (as opposed to a ducted fan), is a type of aircraft engine related in concept to both the turboprop and turbofan, but distinct from both. The design is intended to offer the speed and performance of a turbofan, with the fuel economy of a turboprop. A propfan is typically designed with a large number of short, highly twisted blades, similar to the (ducted) fan in a turbofan engine. For this reason, the propfan has been variously described as an "unducted fan" (UDF) or an "ultra-high-bypass (UHB) turbofan".

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Ag.1 Activates the engine. "It'll go through a startup phase instead of just turning on"

DO NOT USE THE THROTTLE UNLESS YOU ATTACH THIS TO A PLANE, THE ENGINE POWER WILL CAUSE THE STAND TO FLIP EVERYWHERE

Testing the engine on AS49's Learjet 35

It is completely safe to mirror the engine with no worries of complications

Just detach the engine from the stand and save it to you subassemblies. Feel free to use this on your builds just be sure to give me credit where credit is due