Rotary Racer 8 - Design Tasks/Dimensions

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Rotary Racer 8 - Design Tasks/Dimensions

Info Needed

Accurate measurements of the following are required:
  1. Front Wheels: Diameter of wheel, thickness of tyre, thickness of hub.
  2. RearWheels: Diameter of wheel, thickness of tyre, thickness of hub with gear and/or brake.
  3. Minimum frame width where driver fits (500mm outside with 25mm tubes ?)
  4. Minimum frame width where front wheels go to allow a 10m diameter turning circle

Design Decisions

  1. Width of frame at front and rear
  2. How to join tubes at centre
  3. Overal width of car (mininum we can get)
  4. Check if drivers will fit
  5. How to make side panels with rounded edges (foam/ply with wood joining fillet ??)
  6. How to make front/rear foam bumpers.
  7. Will batteries fit at correct height
  8. Will motor fit, how about chain path how to mount.
  9. Will drives feet fit in narrow front section.
  10. How big a drivers opening
  11. How to open car rear for batteries
  12. How to make spats for rear wheels
  13. Should rear wheels be internal ?
  14. How to make and mount rear subframe
  15. How to make and mount front steering
  16. How to mount seat, more stretched out position.
  17. Where to mount Electronics.

Dimensions

Item Description
Body 2500 x 600 x 400mm (100mm above ground at centre)
Wheels Axles at 720 and 2080 from front of car
Wheel Width Tyres 25mm, Wheel cone sides 25mm, Hub width 75mm
Wheel Diameter Tyre diameter (Continental Grand Prix 460-28) 480mm

Steering Geometry

  • Kingpins should be inclined so that they hit the floor 10mm from the tyre center line. This gives some feel but should be fairly insensitve to bumps. This will be in the order of 14 degrees.
  • Kingpins should be inclined about 4 degrees backwards to get a suitable caster angle (current car has about 0 degrees ...).
  • Steering arms, behind steering should be inclined inwards.  We will need to calculate this angle using the Ackermann steering calculator at: http://www.eland.org.uk/steer_download.html. We need the distance between axles, the distance of the kingpins from the centre line, the length of the steering arms and steering column arm to calculate this. An approximate angle would be that so that they point to the centre of the car at the rear axle.

Parts

Item Description
Frame Frame from 25mm x 1.6mm aluminium tubing joined with plastic fittings
Rear Subframe 22mm x 1.3mm steel box section and 25mm x 1.6mm steel tube
Steering lever Need plastic bushes for pivot points (2 x)
Nose Cone
Rear bumper
Side panels