Student racers make the most of rapid prototypes

The Oxford Brookes Formula Student Automotive Engineering team uses parts produced using selective laser sintering in its bid for racing honours.

Formula Student is an international competition run by the Institute of Mechanical Engineers that challenges students from more than 70 universities from around the world to design, analyse and build a single-seater high performance racing car as part of their automotive engineering degree courses.

After rigorous testing, they take part in racing events in the UK and USA, where the concept is, essentially, to win.

Restrictions are placed on the design of the car frame and engine, so the students' knowledge, creativity and imagination are tested.

Four-stroke engines up to 610cm3 can be turbocharged or supercharged to add a new dimension to the challenge of engine design.

3T RPD specialises in the manufacture of rapid prototypes using selective laser sintering (SLS) technology and, working closely with students from the Oxford Brookes Formula Student Automotive Engineering (FSAE) team, has supplied parts for the team's cars in both 2004 and 2005.

The strength, durability and functionality of 3T's SLS components enabled them to be used in anger in true working environments, and as fully operational parts for the duration of both race seasons.

Competing with two cars, 2004 saw some impressive results.

With 3T supplying the team with SLS components for the combined plenum chambers and inlet manifold, the students became the top UK team, finishing an impressive 7th overall.

They also picked up 2nd place in the Honda sponsored "Most desirable product prize", along with a 2nd place in the SolidWorks sponsored prize for use of SolidWorks CAD software.

The SLS components survived extensive mapping and dynamometer testing intact, as well as all the competition events, demonstrating the arduous service conditions that such parts can be operated in.

The demands of the programme dictate that the students must fully develop an engine on the dynamometer, install it in the car they have designed and built, then undertake a rigorous test programme, before competing in race events.

The Oxford Brookes team continued its successful partnership with 3T into 2005.

Rules demand a new car be designed and built for each race season, and the team again decided to enter two cars into the contest, with 3T supplying SLS components for the intake systems of both, featuring a nylon plenum chamber, intake trumpet and primary runners.

Ian Cooke, designer of the 2005 rapid prototyped intake and throttle system said: "The benefits of this technique have allowed us to produce a very intricate inlet system, capable of giving us the engine characteristics we need".

"The components are also lightweight and offer plenty of dimensional stability".

"It has really opened the box for us in terms of design".

"We can do things with rapid prototyping that would not otherwise be possible on our tight timescale".

Extensive testing of the 2005 engine took place over a period of three weeks.

During this time, the students ran the engine while carrying out the complete mapping process to develop a sound engine calibration map for all speeds and throttle openings.

The intake systems endured a minimum of 10 hours dynamometer testing to map the fuel and ignition.

In the test cell, peak manifold wall temperature reached approximately 45C, with an air temperature staying at around 30C.

The manifolds had to withstand these conditions for at least 30 minutes at a time for an engine sweep of 3-10,000rev/min.

Most of the heat in the manifold is due to heat radiating from the adjacent cylinder head and exhaust.

The manifold wall temperature peaks at engine speeds of 9000rev/min and at higher speeds the increased airflow prevents the temperature from rising further.

There is also a small amount of heat conducted to the manifold by the injectors, which typically operate at around 55C, but again the nylon SLS components demonstrated no signs of failure and remained fully functional and reliable.

Vibration testing was also carried out and results proved that there were no detrimental effects to the SLS components, despite the engines running between 3000 and 13,000rev/min.

Once the engine had been mapped, it was fitted to the car and tested on the track prior to the competitions.

These test sessions simulated the exact conditions that may have been experienced at the competition, allowing setup of the chassis while checking for reliability.

Tim Plunkett, CEO of 3T, says: "We are extremely pleased with the results of our SLS components, and the fact that they were used in real testing and racing conditions further proves the functionality of our prototypes in true working environments".

"This process can negate the need to go down the more traditional manufacturing routes, whilst still achieving impressive results".

The Oxford Brookes FSAE team are currently celebrating a 13th place finish in the annual FSAE event held at the Pontiac Silverdome, USA.

This is the largest formula car event held in the USA and pitted 140 teams from across the world against each other.

Further awards for the team included a new competition record on the skid pad, registering an average cornering acceleration of 1.41g.

The team also picked up a 3rd place for the Altair Engineering "Innovative engineering concept" award, thanks to a highly innovative "spike" throttle and the rapid prototyped intake system.

Having demonstrated the cars' innovative design, the team then picked up 2nd prise for the Arvin Meritor suspension system award.

Next on the agenda for the Oxford Brookes Team is the 2005 Formula Student event on 7th July 2005 at the Bruntingthorpe Proving Ground.

The team holds very high hopes for the new intake system and is aiming this year for a first place overall.

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