Overview

The Mk I is the original 1/5 scale R/C model car.

The car is scratch-built, except for motor, speed controller and stock parts (nuts and bolts, etc.)  It is to my own original design and based loosely on SUV design cues.  It is not designed for any specific competition class.  AutoCAD was used for the engineering drawings and a range of Excel were developed spreadsheets to crunch the design calcs, such as braking system, weight control, suspension geometry and speed/power estimates.

The construction used a range of workshop techniques. The bodywork and chassis are GRP mouldings and the mechanical parts were made using the lathe, milling machine and a range of hand tools.

Specification

• Powered by 750kV outrunner motor, 150A HobbyWing speed controller/BEC and 12V NiMH battery pack (10 D-cells)
• Estimated speed – 20mph
• Rear wheel drive via sun-and-planet differential
• Brakes – hydraulic, sliding pin calliper type.  ESC also has braking function.
• 6 channel control for speed, steering and lights
• Working lights – separately controlled head/tail lights, brake lights, indicators, hazard lights
• Dimensions –  900mm x 390mm x 300mm (length x width x height)
• Wheelbase – 605mm
• Track – 330mm
• Wheel diameter – 168mm (i.e. tyre diameter)
• Tyre width – 60mm
• Weight – 12kg
• Chassis and bodyshell – GRP mouldings
• Wheels – alloy wheels milled from solid, with GRP rims
• Tyres – moulded from silicone rubber, foam filled, reinforced with glass cloth
• Suspension – double wishbone front and rear, with fine adjustment to wheel camber, toe-in/out and wishbone length possible.  Oil-filled coil-over dampers.  Rear suspension geometry gives adjustable compliance steer, i.e. the wheels can be set up to toe-in/out with suspension compression.

Gallery