Rotary Racer Design Ideas

Aero Dynamics

• Could look at using a wind tunnel to try out Aero Dynamic ideas. More info on WindTunnels

• Could get some Aero Dynamic software to try out ideas. (I have seen some software for schools, it costs £250.00 see WindTunnels)

• Space out wheels from chassis.
• Make back of car shorter.

• Could measure the AirDragCoefficient

Batterys/Power Source

• Move to using "new rules" Greenpower batteries. Are these better or worse than current batteries ?
• Make some sort of battery "caddy" to allow batteries to be loaded easier.

Note by Mark Udall With the proposed no charging rule and 4 hour races, we could look at putting all 4 batteries in the car at once and using a changeover switch to swap between batteries, some thought is needed over how best to use the batteries during the race.

Could look at additional power sources:

• Driver driven pedals.
• Solar panels. 1m square of solar panels would produce about 40W of power and cost about £150. In "bright" weather this could give us about 9% extra power. (Have to check these figures ...)

Motor

• Could add an electronic motor speed controller. Ideally this would take information from some instrumentation that knows the current drain from the battery, the battery characteristics and the race length to run the Motor at the optimum power. MotorSpeedController

• Could add a soft-start facility to reduce battery usage during start and save wear and tear on the motor.
• Looking at the motor graphs there does not appear to be an RPM power band. If there is not such a band we could use electronic motor speed control in place of variable ratio gearing. I guess this depends of the efficiency and flexibility of the two methods ...

Gearing

Steering

Instruments

Create a simple dashboard display driven by simple processor system such as the PickAxe system. This could provide the driver with the following info:

• Speed
• Motor Current
• Battery Charge Left

Ideas for measurement:

• Car speed using Cycle computer sensor (actually could just use a complete Cycle computer)
• Battery current and voltage. The unit could then calculate the batterrys state of charge given some knowledge of the battery dynamics.
• Could have radio link for pit-side data.

This could be a inter-team project. More info on CarComputer

Cockpit Bubble

• Use hinges on side of buble and 1 clip on the other side of bubble.

Car Body

Should we start a car from scratch (yeh, I know this is undecided at the mo) I've been scribbling ideas down. What i thought was, we could use the simple front steering idea, take it right to the front of the car and give a bit more leg room. All other things could remain. battery locations, drive area (but with all internal drive if poss) and we could continue the same principles with wheels outside and we may even achieve a good low total frontal area with this approach. The pic enclosed shows the idea although I accept this precise design may be ambitious - I can see the flowing lines being difficult to shape everything, but we could use the same front design on an upgrade to our current 'long square' design with a longer bubble. Apologies for any 'R' pod similarities - I can assure you it was not intentional !

car2.jpg

PaulStretton

Hello All,

This is my second attemp to put something up on the page, I hope it works this time!

I have put some thought with Stef into the direction we should go with a car for next year, particularly with the changes in the regulations. The current car is pretty competitive so we should make sure that changes we make do not lose the things that are clearly good about the car at the moment. I think that the rolling friction and transmission efficiency are very good and the simplicity of the car gives good relaibility. Also the tubular space frame type structure is robust and easy for the kids to participate in its construction.

I believe that the areas for our attention should be improving the aerodynamics and power management to avoid wasting battery capacity. In terms of the chassis, i believe we could construct a more aerodynamically efficient shape using the same construction as per my sketch. presently I think the aiflow around the vehicle causes substatial drag at top speed and is capable of improvement. The front shape is intended to curve in a single plane allowing the use of thin ply.

Any thoughts gratefully received.

Mark and Stef

Car Simulator

This is a software simulator for trying out different car and pit stop configurations. There is a separate page for this named GreenSim. TerryBarnaby. 

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