Thursday 12 August 2010

Why do Caravanners think they need an Aerofoil?

Hi - don't you think Caravanners that fit these Aerofoils to their cars look even more stupid?
Why do they bother - they are no use. Here's why.
Let me start by explaining – we caravanners have all pushed our Vans, yes they are very heavy, and you have to push hard to get them to move much, sometimes its impossible hence the blossoming “Motor Mover” market. So the answer to fuel saving is – go easy on the RIGHT FOOT! Its all simple physics.
I remember from my school days F=Ma. Force=Mass x Acceleration, so the faster you accelerate your outfit the more Force you need hence more Fuel you use – simple! Vans are big and heavy so to get them up to the speed you want take it slow and easy and you’ll save fuel.
Now – cruising. This is where we need the Aerofoil? Wrong. Again F=Ma. On a flat motorway at the legal speed of 60mph why do you need an Aerofoil? Because the Force of the wind resistance is slowing you down all the time – well possibly. In a vacuum without any friction (space) there is no resistance and Newton said “an object will continue to move in a straight line unless some force acts upon it”. So in the real world we have some friction and some force from the air resistance. Basically a Caravan is Brick shaped, no aerodynamics but it is also 8 feet high and 7’6” wide, at 60mph you have to shift that amount of air out of the way as you travel so no aerofoil is going to make any difference to that!
It helps you say, by deflecting the air, yes a bit, but again F=Ma. It’s the force of shifting the air up and over the van and then the “drag” at the back as the air comes back around, why do you think the Porsche is that “teardrop” shape and their little “wing” only comes out at 50mph plus. This is because below 50mph it has no relative benefit.
So, to sum up, my advice, don’t bother with an Aerofoil. Drive smoothly and steadily with a light right foot. If you must accelerate to the speed limit where it is safe to do so do it as slow as practical. Below 50mph weight is the biggest factor to fuel consumption. Or buy a folding Caravan.

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