Perfect planning may prevent poor performance … but a plan is a plan is a plan, until the plan changes.

While I was finishing FT, I considered what I’d learned from the process, and concluded that my biggest lesson was that a bit more planning up front would have saved me a lot of effort (as I said here).

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Given the last couple of harsh winters, and the ever present hysteria about how bad this winter’s going to be, more people are wondering about fitting winter tyres to their cars.

So, what are winter tyres?  They’re tyres (duh) with a very different tread pattern, made from a different compound of rubber, so as to optimise grip in cold, wet, icy or snowy conditions.

All tyres have an optimum working temperature.  You can see a perfect illustration of this in a wet Formula One race: what happens when the track dries out?  The wet tyres used overheat and degrade very quickly – the water keeps the tyres cool.  But the dry tyres used need to reach a much higher temperature to grip effectively: how many drivers spin off on cold tyres after a pit stop?

Road car tyres are nowhere near as specialised as this, but similar principles apply.  Winter tyres use a compound of rubber which is designed to grip at lower temperatures – typically 8°C and below.  Your standard road tyre can begin to lose grip at this point.

This is down in part to a material parameter called the glass transition temperature (stay with me).  A very simple view is that below this temperature, a material crystallises and becomes hard and often brittle; above it, it’s soft and pliable.  The best way to see this in action is put a rubber band in a freezer.  At room temperature, the rubber is stretchy: when it’s frozen, the rubber is brittle and snaps.  The rubber has gone below its glass transition temperature.

That’s the sort of thing that’s happening with your tyres.  The standard tyre  just can’t get warm enough (i.e. soft enough) to grip properly.

[Note: There is much, much more to tyre rubber compounds than this: the ingredients used affect not just the rubber’s operating temperature range but the grip levels (for example, sports tyres generally grip more than your average tyre), the rolling resistance (how hard it is to roll the tyre along the road – many “eco” tyres are low rolling resistance to reduce fuel economy, as the easier it is for the car to roll the less fuel it needs to use to move), and durability (how long it takes for the tyre to wear out).]

Now we come to the tread pattern.  The tread on standard road tyres is designed to move water away from where the tyre meets the road to allow the rubber to contact it: it does this via a pattern of specific grooves in the surface – known as the tread pattern.  If it fails – if the water isn’t driven away – you lose traction, otherwise known as aquaplaning.  Again, you can see this during a wet Formula One race: if a driver inadvertently drives over a patch of standing water, the sudden loss of traction can mean he loses control of the car.

Winter tyre tread patterns look very different to their summer equivalents.  The grooves are more frequent and a very different shape, some almost like wiggly lines cut into the tyre; the tread blocks (the areas of rubber separated by each groove) are much smaller and much more densely packed.

Side-by-side comparison of standard & winter tyres

This is because winter tyres are usually designed to cope with snow as well as cold and rain.   These tiny grooves, the wiggly lines, are called “sipes”, and these are designed not only to move water away more efficiently, but also to bite into the snow to give traction.  The larger grooves of your summer tyres just fill with compacted snow, meaning they don’t grip: the sipes, on the other hand, remain unfilled so the tyre can grip.

What does all this mean?

If you drive an average car and fit winter tyres if it gets cold, you should see a definite improvement in cold and wet weather grip – even if it doesn’t snow.

I definitely have.  I have a small front wheel drive car, with relatively skinny tyres, and a whacking great weight of a diesel engine over the front axle.  It has no electronic traction aids (not even ABS – it’s that old).  In cold, wet weather, on greasy roads, on its usual “eco” low-rolling resistance tyres, it understeers – safely and predictably, but also considerably.

On winter tyres, even on soaked roads, it understeers so much less I turn into corners a bit early until I’ve got used to having more grip.  Puddles of water along the side of the road which previously would’ve pushed the front end all over the place … don’t.  Even under heavy braking, it’s much more stable and sure-footed.

Obviously, this isn’t a licence to be a hooligan, but it gives me much greater confidence that should snow fall, I can keep control of the car.  In fact, when it snowed last year, my car with winter tyres outperformed all those with flash 4x4s who couldn’t get any grip on their summer, performance-oriented tyres.

So, do I think winter tyres are worth it?  Yes, I do.

 

I’ve got to admit, I was quite excited to see the long-awaited, often-rumoured, previously-cancelled Jaguar F-Type finally get launched.  It is a truly beautiful thing in the metal.  It sounds mighty fine too.

But I was disappointed to hear how much Jaguar are going to be charging for one.  I mean, £60k isn’t far short of what they’re charging for the gracefully-ageing XK.

I’m pretty sure, if he saw the prices, Sir William Lyons would be spinning in his grave.  His key ethos was for Jaguar to be affordable luxury sports cars – he wanted to deliver driving pleasure, but at a price people wanted to pay.  Nigh on £60k doesn’t fit many people’s definitions of affordable.  And if it does fit your definition, then probably you’ll be looking more towards Bentleys and Rolls-Royces than Jaguar anyway.

What concerns me is that I can see the Jaguar brand dying in my lifetime.  I know no schoolboys who lust after an XK or XJ. Actually,  I don’t know anyone under the age of about 50 who lusts after any Jaguar of any sort.  And if I had £60k to play with, the first car on my list wouldn’t be an F-Type.  Or any other Jaguar, really*.

This is a real shame, as Jaguar’s engineering integrity and build quality is second-to-none: they deserve to succeed and to thrive, and to match their sister company Land Rover’s frankly astonishing recent revitalisation.

What Jaguar should be aiming for is that mid-market slot, such as currently occupied by the amazing-selling Range Rover Evoque.  Circa £35k is still not cheap, but it brings the brand that bit closer to us younger people who don’t have a ginormous disposable income but want something a bit bling and a bit special.  Why not have a baby Jaguar convertible – or even just a coupe – to compete with the Mazda MX-5, the Audi A3 and A4 convertible (even the VW Eos), the BMW 3-Series cabriolet, the Mercedes SLK?

These cars are selling – in fact, the UK is Europe’s biggest drop-top market, despite our weather – so why is Jaguar not taking advantage of this niche?  Slap in the 2.0 diesel for the mass market – after all, VW, Audi and BMW are selling many diesel convertibles – and have a big petrol engine, with a touch of lairiness, as the “halo car” for the true petrolheads.  Heck, even put a big diesel in it for a shovel-load of torque.  Make it lightweight and rear wheel drive for some real driving excitement.  Revitalise that reputation for producing sweet-handling cars.

Above all, Jaguar need to decide if they want to grow the brand, keep it alive and move it forward (like Land Rover have done with Range Rover).  Basically, they need to get some balls, some fun, some humour, and above all some youth back into the brand.  You can sell an old man a young man’s car, but you’ll never sell a young man an old man’s car.  The X-Type proved that.

Oh, and Jaguar, please stop with this po-faced pretension of cold, aloof stylishness in your advertising.  It’s not fooling anyone.

*XF is all right, but even the Sportbrake wouldn’t suit us as we haul too much crap around; XJ just doesn’t float my boat styling-wise (love the aggression at the front: but the back and sides make it look like the bastard offspring of a Citroen and an Audi); XK is nice enough but looks like it should belong to the newly-retired gentleman at your local golf club with a trophy wife (and a trophy mistress, if said gentleman has the XK-RS).

This draft has been sitting on my hard drive for ages, but this is the first chance I’ve had to post up my summary of the trial TSR-2 bake.  I photoblogged the sequence in it’s entirety here.  Enjoy!

Despite having had a horrible cold that knocked me off my feet for a few days, I still decided to press on with the trial bake: that weekend was my only definite free weekend for some time, and I’d already bought all the ingredients.

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After Phase #1’s rundown, it was clear that the most critical unknown and undefined item was the wing material.

[The second unknown – how much TSR2-shaped cake a 30cm length bake would yield – was answered by referring to a scale drawing, using a ruler and doing some sums.  It turns out 30cm length of cake (not including engine exhausts or the nose cone) gives a maximum fuselage width of 5cm (including icing).  That’s not much cake.  I think my first trial bake will need to be a 40cm one, diagonally cut from a 30cm square cake.]

Having a spare afternoon on my hands, and the ingredients sitting in my cupboard, I decided to do a trial run with pastillage.  According to the book I’m using as reference (Lindy Smith’s The Contemporary Cake Decorating Bible), pastillage is best suited for pieces of decoration which extend above and beyond the sides of a cake – like, for example, wings.

I think I can best sum up my learning in two parts: material and design.

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