TRACMAC BLOG

014 TM0 blog: Part 5

Wed, 25 Apr 2012 16:23:08 +1000

This week we’re talking about how critical it is to keep the mass of a race car as low as possible. While everyone will say “it’s important” being engineers we have to always know just how important it really is. So we made sure to simulate what the resulting lap time would be if we varied nothing else but the mass of the car.

Our results were quite insightful, while it is common for Formula One teams to quote ~0.4sec per lap per 10Kg this number is often thrown around in conjunction with fuel loading. Our results suggested that for our car design the sensitivity of mass on lap time was about 0.25sec per lap per 10kg. It is important to remember that this number will vary from race track to race track and is also dependent on the cars general parameters such as total mass, aero down force, tire grip and engine power. Nevertheless this constant of 0.025sec/lap/kg will be useful in managing efforts to reduce weight and the overall design of the car. Next week I will continue the design review by covering the effect of the vertical placement of center of gravity height (CG) on a race car and its lap time.

Thanks for reading! Until next time,

-Andrew Tolhurst

014 TM0 blog: Part 4

Tue, 17 Apr 2012 18:29:15 +1000

This week’s post is on wheel base. Our simulated results show that there is a minimal change in lap time with changing the cars wheel base. This is most likely due to the weight distribution being held constant while wheel base is varied. In the real world, if we varied the wheel base of the car without changing the layout of the sub systems this would cause the weight distribution to also change. Therefore both should be considered when selecting a wheel base as it was shown in Part 2 of this blog that lap time is extremely sensitive to weight distribution. Generally, a good rule of thumb to keep in mind is the longer the wheel base the more stable the car will be at the trade off to turn in response.

Any reduction of lap time shown in the simulation output would be gains under braking as the longer wheel base would reduce the total amount of weight transfer under acceleration in both the positive and negative directions. Next week I will continue the design review by covering the real effect of extra mass on a race car.

Thanks for reading! Until next time,

-Andrew Tolhurst

014 TM0 blog: Part 3

Tue, 10 Apr 2012 09:07:59 +1000

This week’s post is on front/rear Track width. As with any simulation it is important to fully understand what assumptions are made, and our simulation is no different. In order to reduce simulation computation time only steady state cornering was considered and transient acceleration/braking. As a result of this the output for lap time vs track width suggests that the wider the track width the quicker the lap time will be. This is however not valid for extremely tight tracks which extremely rapid changes in direction (like auto cross tracks). In this situation the polar moment of inertia increase associated with increasing the track width would also reduce the responsiveness of the car on turn in and hence make the car slower on an overall lap.

However as this car is designed for more open free flowing tracks; this assumption was considered valid and instead of looking at a graph and picking an optimum, other considerations need to be taken into account when selecting the track width. These include:

· any track width/total width restrictions in any possible racing series the car is likely to compete in,

· the maximum safe width of a car that can be road registered, and

· a common width of car trailers as the car may be trailered to a race track.

Whichever of these has the minimum width will be the determining factor of the cars designed track width. Next week I will continue the design review by covering the wheel base simulation results.

Thanks for reading! Until next time,

-Andrew Tolhurst

014 – TM0 blog: Part 2

Mon, 02 Apr 2012 16:59:58 +1000

Over the next few weeks I will be covering some of the simulation results we are using to design some of the fundamental parameters of the TM0. This week’s post is on front/rear weight distribution. Our tyre model simulates the weight sensitivity of the tyres and we intended to develop a more refined tyre model once we have a prototype on track to use as a test bed and measure actual forces on. This will give us the ability to validate our simulation and make tuning/design changes more efficient.

Our understanding of the results shown is: up unit a point (shown to be ~43%) the gains of increased braking performance on this particular race track outweighs the loss of ultimate cornering grip (assuming same tyres are used front and rear). However once you pass this optimum point the loss of cornering acceleration overcomes any gains in braking performance. I would also like to point out that the data shown is the output from our own simulation software developed in house and is only valid for the particular design parameters that are unique to our design for the TM0 at the race track simulated. Next week I will continue the design with track width. While we are completing this project join us by sharing what car you like to take to the race track.

Thanks for reading! Until next time,

-Andrew Tolhurst

Project: 014 – TM0 blog

Mon, 26 Mar 2012 21:23:00 +1100

Hello world! This is my story: In the pursuit of lateral acceleration and the thrill of driving…

For as long as I can remember I have been a fan of motorsport and since my days in school I have been sketching cars and race tracks. So now that I run my own engineering company I guess it’s the best time to finally tackle a project as big as a high performance car designed and built by drivers, for drivers. So I hope you enjoy reading about our project: The TM0, a real driver’s car!

The story of this car actually starts roughly 8 years ago, 2004-2005 (favourite race team: Williams F1):

I was still in school and while I was alright at drafting, the drawing of the car itself was very crude, never the less this was the first evidence on paper to show that there was going to be a car at some point with my name as the lead designer.

Now jump forward 2 years to 2006 (favourite race team: Red bull F1):

I had just completed one year of helping out a local weekend racer (Mark Telfer) who raced a future tourer which is a lot like a V8 supercar but regulated to reduce the power/speed potential of the car and to stop owners/drivers spending millions on the car. My role in the garage and at the racetrack involved preparing the car for racing at several events all over Australia and it itself gave a great insight into real world racing.

Now jump forward 3 years to 2009 (favourite race team: Red bull F1):

The experience I had gained to date put me in a better situation to design a car that can outperform most! So in my spare time around Uni work I started modelling up concepts and completed my Thesis on the Aero Dynamic Design of a race car body. More importantly I was always deriving equations in my scrap book that I would need in order to simulate a race car around a race track. This included both kinematic calculations (mostly trigonometry in 3 dimensions) and transient dynamic calculations (in 4 dimensions, 3 + time). With all of these equations on hand I could then incorporate some matrices and other macros in an excel spread sheet in order to simultaneously solve several equations in order to find the “best guess” for each parameter of a race car around a race track, more specifically Wakefield in NSW, Australia. Nothing special but I made sure that the input parameters of the race track could also be adjusted, so out of curiosity I will get around to putting in the parameters of the Top Gear Test Track (UK) to be able to predict a lap time, should we be so lucky to have the Stig drive the TM0 around that track!

At this point I had also started to see DIY track day cars jump up out of nowhere and go into production! They were multiplying like rabbits but they all seemed to have the same theme… they were all cars built around a body style/shape (props to the Aerial Atom for breaking the mould, and it itself has its own line of copiers), but had little or no regard for sound engineering practices under the body in chassis/suspension design, often just copying what they saw in road car suspension which is cheap but far from ideal. So I realised that what was missing was a car with a body built around the car not the other way around!

When I completed my thesis at UOW it gave me the ability to design a car with more down force than was needed, but I wanted to focus the design around mechanical grip and optimise the body to reduce drag and provide some down force but not to the point where the chassis would have to be set up for high speed cornering leaving it to understeer at most points of operation. Let’s face it we can’t all drive like the Stig although in this sport most would like to think they can. So why not have a car that is fun for everyone from the novice weekend driver to the hard core racer!

It is commonly unknown that what makes a good chassis for mechanical grip does not leave the easiest shape for a “sexy” body, but this is going to be a driver’s car, not a car for a hair dresser… However if by accident we stubble on a “sexy” design that works with the chassis we won’t throw the baby out with the bathwater.

Ok sorry for the long intro, now down to business! Here’s what I’m going to do:

Project brief: To design and build a car that is for real drivers! Particular care should be given to performance in: Brakes, Mechanical Grip, Brakes, Steering/Pedal Feedback, Brakes, Throttle control, and finally Brakes! (Guess which is the most important system on a race car…). The finished product should also be reasonably priced to make it affordable to most drivers, not just the privileged few.

Design goals: The car should have the following parameters:

Initial design is to be a track day car only:

· Sub 550Kg

· Two seats

· Rear wheel drive

· Slick and/or Semi Slick tyres

· Petrol Power-train: Hayabusa engine, Supercharged FI, single limited slip differential

· Power to weight ratio > 0.5kW/Kg or 667hp/Ton or 0.3hp/lb

· Expected traction ellipse: 2.2 G lateral, 2.5G braking, 0.8G acceleration.

Road legal model will succeed this

· Sub 650Kg

· Two seats

· All-wheel drive

· Semi Slick tyres

· Electric Power-train: TBA

· Power to weight ratio > 0.83kW/Kg or 1111hp/Ton or 0.5hp/lb

· Expected traction ellipse: 1.8 G lateral, 2.2G braking, 1.0G acceleration.

So join us for this crazy ride as we finish the design of the TM0 and move towards prototyping and testing. As with anything we are very open to feedback. If you feel we have not paid enough attention on the design of a particular part by all means point it out! Ask a question and we will do our best to address your concern in a timely fashion. Each weekend I will do my best to compile my week’s progress in a form of a Blog post it up for your enjoyment and to get feedback on how you see the design to be progressing so I can tweak my actions in the following week.

Next week I will be going over some of the simulation results in order to determine the TM0’s foot print and its other fundamental parameters. So stay tuned!

Thanks for reading! Until next time,

-Andrew Tolhurst

Tracmac Blog Launched

Fri, 16 Mar 2012 19:08:00 +1100

Welcome to the new Tracmac Blog. Here we will show you upcoming products and examples of some of the great products we have been working on along with things you may find interesting.

Thanks for the support so far.

-Blake Newman