The Carson KING OF DIRT - 4WD is a 1:8 scale off-road nitro buggy with permanent all-wheel drive, designed for use on loose surfaces such as dirt and gravel. The vehicle is based on a torsionally rigid aluminum chassis with a centrally positioned engine and fuel tank for optimized weight distribution. It is powered by a .21-class two-stroke nitro engine, coupled to a multi-plate centrifugal clutch and a central gearbox with driveshafts to the front and rear differentials.

The independent suspension with double wishbones, adjustable oil-filled shock absorbers, and variable track and camber settings allows for precise adaptation to different track conditions. Enclosed differentials, large off-road wheels, a center-mounted disc brake system, and an aerodynamically shaped polycarbonate body characterize the model's robust, competition-oriented design.

In this setup, the O.S. ENGINES OS-MAX-21VG-PES used.

ENGINE GROUP OVERVIEW

1. Chassis

Aluminum chassis (CNC-machined or stamped)

Integrated engine and tank mount

Side guards

Front and rear bumpers

2. Drive unit

Two-stroke nitro engine .21 class (≈3.5 cm³)

Centrifugal clutch with clutch bell

Primary gear / spur gear

Central cardan shaft drive (front / rear)

Front and rear axle differential (bevel gear)

3. Fuel system

Plastic tank (approx. 120–150 ml)

Fuel tank cap with vent

Fuel lines (silicone)

Resonance pipe / exhaust system

4. Brake system

Mechanical disc brake

Brake disc on center shaft

Control via throttle/brake servo



5. Chassis

Independent suspension all around

Double wishbone front and rear

Steering knuckle with C-hubs (front)

Adjustable tie rods (toe/camber)

6. Damping

4 oil pressure shock absorbers

Aluminum damper housing

Coil springs (replaceable)

Upper damper bridges (plastic / aluminum)

7. Steering

Servo saver

Double-arm steering linkage

Ackermann-like steering geometry

Standard servo mount

8. Electronics (RC components)

Throttle/brake servo

steering servo

Receiver box (splashproof)

Battery holder for receiver battery (5-6 cells)

9. Wheels / Body

1:8 buggy rims, 17 mm hex

Knobby tires for off-road

Polycarbonate body

Rear spoiler, height and angle adjustable

DIGITAL REBUILD

In 2025 I was still convinced that the digital restoration of my Graupner BELL-47G It was my most extensive project to date.

However, after their completion, the question arose: Should we start something completely new – or finally complete one of the many projects already started?

A look at my file server revealed two candidates: the Carson KING OF DIRT - 4WD or the Schlüter Heli Baby.

The decision ultimately fell on the buggy – my second oldest project. (My first model project, by the way, was the Heli Baby from 2009.) Purely in terms of project progress, I was already significantly further along with the KING OF DIRT - 4WD: apart from the body and decals, almost everything was modeled in CAD.

The O.S. ENGINES OS-MAX-21VG-PES motor wasn't quite in the CADDICTED style yet. So, the motor was completed first, before I turned my attention to the remaining components in November 2025.

BODY & FREEFORM SURFACES DESIGN

I'd tried my hand at modeling the body shell several times over the past few years – with rather limited success. It was only the experience gained from modeling the clear canopy of the BELL-47G that brought the breakthrough. The entire body shell was created as a consistent freeform surface design – including the paintwork. Even the decals and logos were entirely created in CAD. From a modeling perspective, this is quite challenging. I might make two or three YouTube tutorials about it. Interested?

BLUEPRINT DESIGN

The CAD-images were created relatively quickly. Preparing the blueprints, however, was significantly more time-consuming:

• Add order numbers and descriptions of all parts to the parts lists.
• Design of thread details for screws and blind holes.
• Selection of meaningful sectional views.
• Determining the optimal layout on the blueprint pages.

As is so often the case, a single page was not enough. After a few days' break and several iterations, the final layout was determined: three blueprint pages.

You can find them here on the website on the MEDIA subpage. Feedback is always welcome. If you are interested in the full-resolution versions, feel free to contact me here.

Printed in a format of 1000 × 700 mm, the whole thing looks particularly impressive. ;o)

TECHNICAL PROJECT DATA

For all CAD-enthusiasts, here are a few more interesting facts:

• 810 components including standard parts
• 369 individual components
• 62 assemblies
• Largest assembly: 26 MB
• Largest single component: 14 MB

The design is modeled to be fully functional mechanically, including:

• Spring shock absorbers
• Complete drivetrain (crankshaft → differentials → drive shafts)
• Correctly depicted translation ratio
• Functional steering
• Brake system including servo control

CAD software used:

• PTC Wildfire 4.0
• From 2011 onwards: PTC Creo
  

DETAILED IMAGES

BLUEPRINTS