AC3D Converter
FileFlip converts AC3D files into 14 other formats entirely inside your browser, using Assimp compiled to WebAssembly. The AC3D file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. There is no file-size limit and no account to create.
How do I convert an AC3D file?#
- Drop your AC3D file onto the converter at the top of this page, or click it to pick one from your computer.
- Choose the format you want out of it. FileFlip downloads the engine that conversion needs, once, and your browser caches it.
- Conversion starts the moment you pick the format, and the result is yours to download. The work happens in this tab, so nothing is uploaded and nothing is queued.
Is it safe to convert AC3D files online?#
Yes, because nothing is uploaded. FileFlip converts AC3D files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What happens to a AC3D file#
FileFlip converts AC3D into 14 formats with Assimp, all of it inside the browser tab. Each conversion below names the engine it uses, what it downloads, and exactly what that conversion keeps or drops.
| Category | 3D Models |
|---|---|
| File extension | .ac |
| FileFlip support | Read only, so it is a source rather than a target |
| Conversions available | 14 |
| Engines | Assimp |
| Downloaded to your browser | 11.2 MB on the first conversion, then cached |
What is an AC3D file?#
An AC file is the plain-text scene format written by AC3D, a modeller aimed at flight-simulator and hobbyist work, storing a hierarchy of numbered OBJECT entries that each carry their own surfaces, materials and texture references.
Use AC when the destination is FlightGear or another AC3D-based scenery pipeline, since that's what the format was built to feed.
Convert AC to OBJ or glTF once a model needs to leave the flight-sim world, since few applications outside it open AC3D natively.
The AC3D file format reference covers the specification, the programs that open one, and what each conversion keeps or drops.
AC3D questions people ask#
What software creates AC files?
AC files are written by AC3D, a modeller used mainly for flight-simulator aircraft and scenery. FlightGear loads .ac files directly as its native model format, which is why so much of that content exists as AC files.
Is an AC file the same as AC3D or ACC?
An AC file and an AC3D file are the identical format under two spellings of the same extension. ACC is close enough that the same parser reads it, but it adds one extra surface type for triangle strips that TORCS and Speed Dreams use for smoothing and shadow mapping.
Does an AC file support animation?
No. An AC file describes static geometry, materials and an object hierarchy, with nothing for bones, skinning or keyframes. Anything animated has to be handled outside the format, which is one reason AC models get converted to formats like glTF for modern use.