The van is fixed! (by alaric)

After the van's sad demise, it went off to Sarah's excellent uncle David to be fixed.

Anyway, he sorted it out, and I picked it up last weekend, but I've only had a moment to write about it now!

Basically, the front right wishbone had broken. It's a big triangular metal thing that attaches to the chassis on two hinges, and then attaches to the wheel at the other end, with the shock absorber coming down into the middle. As the van rides over bumps, it pivots on the hinges, regulated by the shock absorber. So it plays an important part in supporting the weight of the van.

However, knowing I'd be interested, after replacing it with a new one, David put the broken one in the van for me to take a look at!

I'd have expected something like this to be a solid casting - but no, it's two pressed sheet steel shapes welded together, making a hollow body. It looks like thick steel, 3mm or so, but near where it's cracked apart, it's more like 1mm. I presume that's due to corrosion over the years.

Here's the new one - in situ, under the van. It's the shinier, blacker, cleaner looking part, although it's already picked up quite a bit of mud.

The old one is now in the little garage, awaiting cutting apart to investigate its construction and exact reason for failure, then WELDING PRACTICE!

Synchrony! (by alaric)

Our week goes like this.

Monday morning, Sarah gets on a train to London.

Wednesday evening, at 8:30pm, I get on a train to London (Jean is with her grandfather for this bit). Then at 10:15pm Sarah gets on a train back from London, the same time as my train gets in. She gets home at about midnight, then on Saturday, I come home and we get the weekend together before she goes off again next Monday morning. This is not a very pleasant state of affairs - we're a close couple, and we miss each other keenly.

Anyway, this evening, my train into Paddington was a bit early - so I rang her as my train was pulling in at 10:09. She was in coach D of the train on platform 2, waiting for it to go; my train came in on platform 3, and I was in coach E. Platforms 2 and 3 are opposite sides of the same physical platform. So I got out, crossed the platform, walked one carriage down, and there was Sarah! She came to the door of the train, and we had an unexpected five minutes together!

Fun in computer games (by alaric)

I've noticed a pattern in computer games which I find fun. Not all games I find fun; they can be fun in different ways. I'm just saying I've noticed a particular element which subtly contributes towards the funness.

Namely, having to make a tradeoff between two or more competing requirements.

Let's have an example - Desktop Tower Defence. It's a tower defence game, which means that you use your resources to build a set of defences that waves of attackers then flow into.

Firstly, clever placement of defences has a much greater effect than simply how much you spend on them. So the game requires some measure of thought, rather than repetitive accumulation of resources followed by spending them.

But the crux of the matter is that there are different kinds of attackers, which have different weaknesses. A defence set up in the way that would be the strongest against land-based attackers - a long winding zig-zag with turrets along it - would be weak against flying attackers, since they just fly over your layout in a straight line rather than being constrained to the paths. Against them, you want a solid block of turrets in a cross, under the two orthogonal lines they fly along. So you need to establish some tradeoff between the two challenges. Not to mention that there are turrets which only attack air targets, but have a high damage per cost ratio, and turrets which only attack ground targets, and turrets that attack both but have a worse damage per cost ratio. And turrets with long ranges, or high fire rates, or that do a lot of damage per shot, or damage neighbouring targets due to a splash effect, and so on.

Sometimes you can have a tradeoff that's too simple - it's amenable to mathematical analysis to find an optimal result. That's no good. It has to be too complex to work out on paper, but not too complex to grasp. The middle ground between the two is the area where experimentation is rewarding.

I probably ought to read A Theory of Fun for Game Design...

Plan B (by alaric)

I've hired a car to take up to the Lake District this weekend.

A Peugeot 308 with 350 miles on the clock that smells of new, picked up in London Euston, drop off in Gloucester, four days, for £166 from Avis at zero notice and with nothing more than a debit card and a clean licence with the same name on and a photo that matches my face - not bad at all. 1car1 was offering £200 for the same thing, but I'd need a utility bill, which by some miracle I don't happen to normally carry with me!

The van will stay here until I return next week and then I'll transport it to a place of fixing.

I broke the van! (by alaric)

While in London with the van, I had to deliver a server to a data centre - (InterXion London)[http://www.datacentermap.com/united-kingdom/london/interxion-london.html]. There's parking at the DC, but it's £20 to park a van there, so I decided to try and get into the car park marked just north of it on the map, in Quaker Street.

While I could find the car park, I couldn't find the way in - I could see cars all parked behind a fence, but no sign of the entrance. But while navigating the narrow little roads, I had to turn around in Grey Eagle Street:

View Larger Map

The road was narrow, only a single track, but with a wide pavement, so I opted for a three point turn. I turned hard right to bring the front of the van up onto the pavement, and the right wheel went up, but then I heard a grinding scraping noise. I was a bit surprised to be bottoming out on a not-particularly-high kerb, but I reversed back and found a place further down with a dropped kerb (but less pavement, since there was a car parked up there) to turn.

However, I noticed that my steering was suddenly a bit funny. I had to hold the wheel at about seventy degrees left to drive in a straight line. And the suspension felt odd - I could feel every little stone in the road, and if I went over even the slightest bump, I heard a funny creaking sound.

BAD NEWS!

After a quick check for visible signs of damage as soon as I had parked (none), I did the business of the evening, and then drove carefully back to Highgate for a closer look.

I parked with the wheel perfectly straight, then got out and looked at both wheels.

Here's the left one, pointing nice and straight ahead:

And here's the right one... pointing twenty or so degrees to the right:

Looks like the tracking's totally out, then.

And by the scientific method of placing my hand in the gap between top of tyre and wheel arch then holding it still while I walk around and try on the other side, the right hand side seems an inch or so lower than the left, too.

And all this when I'm supposed to be doing a five-hour drive up motorways tomorrow evening. Eeek.

I'm going to see if I can find a place to look at my tracking and suspension first thing tomorrow... but I'm dreading what it'll cost, and doubting I'll get it fixed the same day...