What’s the g-force in a rally car?

Photograph by RX-Guru at German Wikipedia - Transferred from de.wikipedia to Commons., CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2080303

Photograph by RX-Guru at German Wikipedia – Transferred from de.wikipedia to Commons., CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2080303

An FIA rally-cross car can accelerate from 0-60 mph in 2 seconds.

Lets check equations of motion, first some definitions.
u – initial velocity
v – final velocity
a – acceleration
t – time
s – displacement

v = u + at
s = ut + ½at2
v2= u2+ 2as

BBC Bitesize resource on equations of motion.

v is 60 mph is 26.8224 m/s
and average acceleration = 26.8224 / 2 = 13.4112 m/s^2
= 13.4112 / 9.80665 g
= 1.368 g
~ 1.4 g

Back calculating….

v = u + at
v = 0 + 13.4112 * 2

OK, in agreement with what we expected.

Distance travelled
s = ut + 1/2 * a t2
= 0 + 0.5 * 13.4112 * 4
= 2 * 13.4112
= 26.8224 m
~ 26.8 m

Rally car

By Foto: Stefan Brending, Lizenz: Creative Commons by-sa-3.0 de, CC BY-SA 3.0 de, https://commons.wikimedia.org/w/index.php?curid=35347288


Fuel efficiency of Bloodhound SCC

1000 miles / hour

1609.34 kilometer / hour

0.4470 kilometers / second

447 meters / second

40 liters / second

0.0895 liters / meter

89.5 litres / kilometer

56 litres / mile

14.8 gallons / mile

0.068 miles / gallon

Kinetic energy recovery for buses

Anyone who has watched formula one racing and experience a bus journey will appreciate the similarities, as buses repeatedly accelerate and decelerate for bus stops and junctions in the same way as the formula one car is repeatedly changing acceleration to allow it to be steered around corners.

A kinetic energy recovery system (KERS) usually stores energy during breaking in a device such as a flywheel, battery or capacitor.

Torotrak has recognised this too, and sees a good fit between capability of their kinetic energy recovery system and the service of London buses.


I think this presents a good opportunity to remove pollution caused by stresses on engines as they try to move off from a stop. Just look at any place where a bus regularly stops (like rising bollards, junctions) and you will see how the smoke has built up on the road and surrounding street furniture.

Suppliers of kinetic energy recovery systems will emphasise the devices can often be retrofitted onto existing vehicles. However I think they could also enable vehicles to achieve the same accelerations or torques with lower powered engines. Heavy vehicles like a bus could be redesigned with smaller engines, not normally able to accelerate from a stop, by storing power in the KERS system while the bus is not moving, rather than only during braking.

Just to try out latex in wordpress (only included since 2007!)…
\mathrm{K.E.} = \frac{1}{2} m v^2

(extensive use of latex in wordpress can be seen here)

Tata Nano

Tata motors dream of a “1 Lakh car” was realised earlier this month when the revealed their new “Nano” car.

I believe that production has yet to start, I would be interested to know the price of the previous small cars when they where released. Such as the original ‘mini’ and the other ‘peoples car’ the Volkswagen Beatle.

DeLorean manufacture to resume

This iconic car is well remembered because of it’s appearance in the Back to the Future movies. Now there are plans to build a small number of the cars. The DeLoreans will be built in a suburb of Houston, Texas, where Liverpool born Stephen Wynne has a 3,700 sq m warehouse chock-full of DeLorean car parts, which were sold by the liquidators when the company flamed out after less than two years of production. Until now Mr Wynne has been using the spare parts to maintain the 9000 cars that were originally built during the two years of production.

The car was made with a stainless steel body, this saved on capital costs since no paint baking line was needed. Possibly a better solution than Henry ford making all of his Model-T cars black because the paint dried faster.

Picture from Wikipedia DeLorean DMC-12 article

The Gaurdian business supplement had a story in August covering the plans to resume production: Back to the Present for DeLorean.

The UK government originally invested £78 million UKP to attract production of the DeLorean to Northern Ireland. That works out as a subsidy of £8667 UKP per car. Margret Thatcher became Prime Minister in 1979 and was a person who took a dim view of government subsidy of industry. However the cars were to be built in a employment black spot, and Nothern Ireland was a hot political issue.

John DeLorean was arrested suspected of Drug Trafficking in 1982 by the FBI but was found not guilty in of the charges in 1984 after using a defense based on Entrapment – the accusation was that the money from trafficking was meant to bail out the ailing company.

The new DeLorean company plans to make around 25 cars per year. With basic price of $58000 USD.

Light cars

Heavy cars may be good for the owners but worse for the environment. Roel Boesenkool of Corus presented a the SMEA conference. He noted that new cars are heavier despite technology being developed that could easilty make them lighter. I wrote about this in the previous post about light cars.

The light ineffiecient car is the Ferrari.

I guess fuel doesn’t cost enough yet.

Weight and Fuel Consumption of Cars
Roel Boesenkool presented this graph at SMEA conference in sheffield

Light cars

The ultra-light-steel-autobody, ULSAB, project was meant to make cars lighter. This project by a consortium of steel companies, largly with the aim of ensuring that steels continue to be used in car bodies. Car bodies have got lighter, but in the meantime cars have become heavier. This is achieved by using higher strength steels.

The reasons given by car manufacturers is the increased safety and performance offered by the cars. It would be interesting to see how much the weight of plastics in cars is increasing, with interiors becoming more plush. If you are in a heavy car it is suggested you have a better chance of surviving a crash. Heavier cars with bigger engines feel better to drive than small cars with small engines, and are more expensive and prestigous. These are that cars that people want to buy.

Police using a small car in Vienna, Photograph by Joachim Rajek
Photograph: Police using a small car in Vienna, Photograph by Joachim Rajek

This is only really a big deal when we consider the fuel consumption of cars and CO2 emissions. For in town driving, fuel consumption is almost linearly related to the weight – with the exception of sports cars like ferrarri, which are light with big inefficient engines. The only real way people are going to start considering fuel consumption as important is if the price of fuel rises. Do we need a CO2 tax to make this happen or should we just increase the tax on petrol and diesel?