Acromaster 4D [STOCK + DLC]
by _dan
uploaded 2024-04-19
mod+DLC aircraft
#edge540 #aerobatic #4d #3d #racer

KSP’s Top-Class Aerobatic Performance

The Acromaster 4D


  • Type: SPH
  • Class: Aircraft
  • Pure Stock
  • Part Count: 70
  • KSP: 1.12.5

^ The Acromaster 4D-S (Smoke) in an aggressive knife-edge.
Smoke canister is provided by chadgaskerman

DLA Aerospace’s finest aerobatic aircraft

This could well be one of my best-performing and impressive aircraft to date, and my first on KerbalX to use an electric propeller powerplant. This project had humble beginnings and a pretty long story, so buckle in and pull some Gs!

WARNING: This craft is completely stock. KerbalX falsely recognizes the propeller blades as the SSTO Project mod.

The Idea

This concept started in a discussion associated with this TVC prop plane with user kyloporg, which thanks to inspiration from my Acro-X aerobatic Juno plane and its successor the V2 had been a fairly big influencer of the Hinged Thrust Vectoring concept, creating multiple different testbeds and replicas. After he uploaded his prop-plane testbed I really liked the concept and figured I would put my own spin on it and make it even better, and it sounded like a really cool craft to upload for my followers and my community. And so I got to work at 11 P.M in the evening, fueled by caffeine and the will to excel and develop the best aerobatic airplanes KSP has ever seen.


For this aircraft I took large inspiration from some of my experience in designing, building and flying RC planes: Lighter flies better. This plane is extremely light, weighing in at around 3.8 tons, which is virtually nothing by KSP standards. The basis for the design was an aircraft I already know destroys aerobatic competitions in the real world: the legendary Edge 540. I copied the Edge 540’s wing, fuselage and tail geometries but adjusted the positions of the lifting surfaces for optimal flight performance, as KSP isn’t the world’s most accurate flight simulation. One must say that I had cheated to bring down the weight using .craft file editing to achieve better aesthetic appearance, but I have done absolutely no file editing or gravity hacking with this craft, the weight is so low because of one amazing part: Fairings. The entire shape of the nose and tail is achieved via fairings, so the craft’s interior is mostly empty space, or as some might say, is a monocoque. The Mk.0 tanks used are all completely empty as no fuel is needed and excess parts are minimized where aesthetics are not in concern.

Learning to Fly

Flight testing of the Acromaster went fairly smoothly, but not all of the current version’s features were present in the first ever aircraft to fly. The first ever prototype had only a single motor without contra-rotating propellers and no thrust vectoring, to save as much weight as possible, coming in at a very impressive 3.5 tons fully loaded. The features where slowly added while excess weight was shed, trading off some weight savings for increased power and maneuverability. The final version of the Acromaster 4D is the one you have access to, as it has the largest amount of features and provides the most fun flight experience. The release of the original Ultralight Acromaster is exclusive to my discord server, to which a link is provided.


Not much to say here, the Acromaster 4D is undoubtebly a very capable aircraft, and it can handle pretty much anything you throw at it. High-G or Low-G, High or Low AoA, Fast or Slow, it will perform as you’d expect. A great way to describe it would be Mild to Wild. The photos provide a good idea of the way the Acromaster performs when in a skilled pilot’s hands. One thing to be aware of for newer pilots trying out this plane would be to take into account of how floaty the plane is, thanks to the weight reduction work. The start procedure is minimalistic and there isn’t any fancy KAL blade deploy angles to operate the electric powerplant, the throttle simply controls the motor speed. To start up simply press 1, throttle up and you’re off! Blade deploy angles are weird, but they should be somewhere at -67 degrees and 67 degrees on the blades respective to rotation direction. If something doesn’t work for you, reach out in the comments or my discord server.

Sneaky Features

This plane has some tricks up its sleeve with one last feature: Reverse Thrust. This is the component that truly transforms the Acromaster from a 3D capable airplane to a 4D capable airplane. The thrust vectoring combined with this feature lets you have finer control over complex maneuvers and increased overall fun factor. The action group for it is RCS, and when RCS is OFF then the blades are reversed. If you aren’t sure, you can check aerodynamic force overlay by pressing Fn + F12.


Plane go spin haha funny. In all seriousness though, I haven’t released this thing in way too long and have spent way too long on the craft page. The upvotes are really important to me and keep my motivation up to keep doing things like this!

Have Fun!

A stock aircraft called Acromaster 4D [STOCK + DLC]. Built with 70 of the finest parts, its root part is Mark2Cockpit.

Built in the SPH in KSP version 1.12.5.

Photo Gallery

The Acromaster 4D-S in level flight. The smoke canister is visible under the fuselage, but the version here doesn’t have it installed.

Big Wing-Over with the reverse thrust and thrust vectoring in action.

Pulling up into a big loop.

A nice perspective view of the Acromaster in a knife-edge.

Various flatspins and tumbles are possible.

A particularly interesting maneuver, involving flying backwards for a short time period in a falling leaf motion.

Coming in to land.

Hailby Kerman and her Acromaster. Look at that big smile!


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