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Scrapheap Challenge 2004

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Quarter final D – Spy Cars

[ The challenge and teams | Result | Bakewells' diary | Atoms' diary | Science | Related links ]

Science

General science
The designs
Pros and cons

General science

Off-roaders and military reconnaissance vehicles maximise ground clearance by driving technique, pneumatic suspension and shape of the base of the vehicle.

A number of vehicles have pneumatic suspension, which allows the entire chassis of the vehicle to be raised and lowered. The Shadow is a MRV which as well as having pneumatic suspension has a curved bridge-shaped base (much like our double steering car), thus increasing ground clearance.

The designs

Bakewell Puddings

The Bakewell Puddings responded to the covert challenge with aplomb … and a complicated, ambitious build. They went for a recumbent low-rider, on a push-me-pull-you principle.

They took the front end off two old Fiats and stuck them together. With a little help from a lorry suspension air bag, they were able to hinge the vehicle's middle upwards, to help with ground clearance and reduce the turning circle.

The Bakewells had a long, hard day cutting two cars in half, fixing parts together, moving an engine, building a hinge and fixing the airbag mechanism. Their heads were steaming as the final countdown was delivered.

Up 'n Atoms

Up 'n Atoms went for a simpler design than their expert Jim suggested. They opted for a cut-down garden tractor with a trailer on the back. The trailer had a nifty limbo contraption and a circumference minimiser – better known as removing a cushion so Ali's ample belly made it through the course.

The Atoms, despite a terrible start where they had nothing in the build area for several hours, raced through their relatively easy design and had time to spare at the end of the day when they took their completed motor on an unheard of test drive.

Pros and cons

Bakewell Puddings

Pros

• The air bag allowed them to adapt the vehicle to the bumps and dips of the course
• Inflating the bag push the centre of the car upwards at the hinge, decreasing the vehicle's wheel base and raising the ground clearance
• The Bakewells had a vehicle with two front ends to give it four-wheel steering. Provided the two drivers could work together, the spy car should be fantastically manoeuvrable

• It was tricky to build and drive
• The drivers would have to work well together otherwise the four-wheel steering mechanism would be more of a hindrance than a help
• The hinge also needed to be able to withstand huge stresses

• It was simple to build
• The garden mower was powered by a horizontal engine which was very low to the ground, to make it easy to sneak under the lasers
• The hitch between the tractor and the trailer allowed the vehicle a wide range of movement without straining the joint. This gave the Atoms a great deal of manoeuvrability both up and down the ramps and around the tight corners

• The tiny engine had to pull four burly Atoms so it was a slow vehicle and the engine was under quite a lot of strain, particularly going up those steep ramps