The front subframe also now has a diagonal strut on each side, further strengthening it, which is no bad thing given that’s where a lot of the force is going to be taken, right over the wheels.  I’ve also widened the front subframe to give me more space between the steering shaft and the drive shaft, which has allowed for a far more compact yet satisfactory connection between engine and drive shaft.  It now runs smoothly and efficiently with only the most essential cogs in between (I want to retain a high cog ratio so that the engine spins fast even when the car is moving slowly).  Oh, and the front subframe has been significantly shortened, too.

I haven’t touched the rear end today, and I still haven’t made a start on the bodywork, but that’ll come.  I figured out today a way of having powered lights in the front (thanks to a couple of my old models), which will be fun.  Not particularly bright, but the effect will still be there.  Just about.  Unfortunately I’m coming down with a cold, so staying up late to work on the project just isn’t going to happen.  I also haven’t taken any photos of today’s progress, so I’ll try to do that tomorrow morning when there’s some nice natural light, and update this post with some close-up shots. Photos now included!

Next on my list of things to sort out was the rear axle, which just looked plain ugly.  It would do the job, and would probably be mostly hidden by the bodywork once that was figured out, but I just didn’t like the way it looked or the way it worked – it just wasn’t realistic in any way shape or form.  So that was stripped out too.

In its place is a rear axle that is lighter, uses far fewer pieces, and actually works more realistically too.  I’ve shortened the wheelbase in the process, which should make the car turn a little easier.  It’s still a live axle (which means the axle is a solid fixed horizontal bar connecting the wheels, so movement on one wheel will affect the other), but as it happens there is enough flexibility in the setup that each wheel can actually move on its own to a certain extent, despite the leading arms – technically it shouldn’t work like that, but I think it’s just loose enough to allow it.  The next test will be to see if it still does that once the rear subframe has been further strengthened; I don’t think the independence is being provided by the twisting of the subframe, but increased rigidity may slightly reduce it.  We’ll see.

So, I’ve got the chassis to a stage now where I’m happy with it.  The engine is smoother too, having replaced the elastic bands with proper cogs.  I even took the car for a test drive around the landing to see how it responded.  The engine makes a reasonable noise, given that it’s made of Lego, and the suspension can handle reasonable-sized bumps on any wheel, which is good.  Next time I’ll be routing the steering to somewhere useful and starting on building some bodywork around the chassis.  It’s all coming together nicely!

I’ve made a start on the rear of the car too, building the rear axle.  Rather than tackling the complexities of independent driven suspension at the rear I’ve gone for a live axle with movement in only one direction.  It makes it a lot simpler, though considerably less realistic – movement on one side of the car will affect the other side just as much, which isn’t ideal.  Still, at least it works.  There’s a differential in there too, and the drive shaft has been connected to the engine at the front of the car.  I wanted to have the engine spinning at a good speed when the car is moving, so I’ve geared it all up accordingly.  Unfortunately that does mean that there’s a fair amount of resistance, but I may be able to live with that.  It may be that I’ll be able to connect in an electric motor later on to drive the engine directly and have it drive the car at a manageable speed.

I’ve also been trying to address the problem of the steering.  While the steering/suspension system that I took from the other model does work, it’s proving a little imprecise.  This is largely down to the ultra-compactness of the steering mechanism, compounded by the big heavy wheels I’m using.  I’ve geared it down as I’ve routed the steering shaft past the engine, but now there is so much play in the action that it’s pretty hard to keep in a straight line, especially when one wheel hits a small bump – the front wheels just turn on their own.  I think I might have to re-think the steering mechanism and try to build a little more control into it, otherwise it’s going to be undrivable.

No idea what sort of car it’s going to be yet, or what it’s going to look like, or even what colour it’s going to be.  I guess that’ll present itself later when the chassis is done.  This project is very evolutionary – it feels like the model is instructing me on how it should be built rather than the other way round!

Today I started work on the front of the car, trying to get a setup capable of steering and suspension in a small space (I want to leave space for the engine in the front too).  In the end I stole an idea from another model, and used the front suspension and steering system almost straight out of the instruction booklet.  The next problem was working out how to connect that solidly to a subframe and not have it get in the way of the drivetrain.

The steering mechanism puts the steering column smack bang in the centre of the subframe, which would be fine were it not for the fact that that’s exactly where I want the drive shaft to be.  I’m going to have to move the steering column to one side eventually so they can sit next to each other.

The engine itself is going to be a V6, connected directly to the rear wheels (no gearbox, no clutch, no electric motor, just keeping things simple for now).

At the moment I’m having real difficulty figuring out how to connect the front axle to the subframe and the engine.  I think I’ll have to sleep on it and see if I can visualise a way through this…

Now, it may appear from this post that I have nothing better to do with my time at the moment than waste countless hours sat in front of a screen twiddling knobs and tapping incessantly on keys without really achieving anything productive.  And they may be a modicum of truth in that hypothesis.  However, I can assure you that the time I have spent playing has been (for the most part) well-chosen and has not adversely interfered with the normal running of my life.  It has of course been lots of fun.

First of all, I recently acquired something I have wanted for years – a steering wheel.  No, not for my car, but for the computer.  And since all my games are now on the PS2, it had to be one that I could plug into that.  An hour or so on eBay and a handful of reviews culminated in a purchase of a Logitech Driving Force EX steering wheel, which was plugged in and tested as soon as I was able (i.e. the evening of the day it arrived – see, I didn’t skip work for this), driving my current favourite game: Gran Turismo 4.

It took a while to get used to, having learnt all the basics of the game using the standard controller, but it wasn’t long before I was hooked.  The steering wheel provided good feedback, with resistence and vibration like a real car, and actually made the cars a lot easier to drive with precision – which is what that particular game is all about.  More recently I’ve even started playing around with drifting and controlling cars on off-road courses, neither of which I could master with a normal controller.  I’ve also found myself preferring to turn off the traction control systems, opting to drive ‘raw’ and more in tune with the car, and that’s rewarded me with a much more pleasing feel to the drive.  And aching arms.

Unfortunately the Driving Force EX isn’t without its faults.  I soon discovered (and later found others who had found the same) that the “flappy paddle” gear change buttons on the back of the steering wheel don’t work with my version of GT4.  Apparently it’s a known issue with that particular steering wheel and my particular release of the game – in other countries it’s absolutely fine.  I’ve scoured all sorts of forums and suchlike, and the general consensus is that there is no solution.  The error itself is in the wiring of the steering wheel, and the option that would usually remedy the situation is bemusingly disabled in PAL versions of the game.  So I’m left with no alternative really but to keep the game in Automatic transmission, missing out on that final piece of absolute control.  Well, I say no alternative, it seems you can get the flappy paddles to work, but only by unplugging the power supply to the steering wheel and using it as if it were a normal controller, meaning you get all the right buttons in the right places but no force feedback.

Still, I’ve had a whale of a time with the wheel so far, and it’s been incredibly addictive.  I’ve spent many late hours screaming round various tracks, wearing tyres ragged and inevitably smashing into my fair share of walls too, but even so there has been the satisfying reward of some awesome corners and moments of superb and flawless control.  The trick now is in reducing the number of accidents and increasing the occurrence of brilliance.

Meanwhile, up on the Mac, I’ve rediscovered (again) my love for Transport Tycoon.  Or, to be more precise, OpenTTD, which is the open-source version that is still being developed and tinkered with by people who refuse to let the game die.  This all started (or restarted, as the case may be) after a trip to London, and my mind got all creative and geeky looking at train station configurations.  So I downloaded the latest version of the game and started playing again, and after a few false starts I’ve got a rail network going now that’s pretty efficient and elegant too.

Something that’s fairly new in the world of OTTD is the idea of “Path Signals”.  There’s a wiki that goes into a little more detail than I can afford here, but basically it’s a type of signal that allows a train to reserve a route through a section of track.  The advantage is that you can have multiple trains using track that would otherwise be limited to one train at a time with the other signal types.  It’s very clever.  In its simplest form it means you can have a really disorganised mass of track, whack some path signals in the right places, and let the trains sort themselves out without worrying about them crashing into each other.  Marvellous.  Obviously it’s a little more complicated than that in practice, but it does allow for much more elegant track designs, with more crossovers, less track, and fewer bottlenecks.  I love it.  I’d show you some screenshots, but the number of people who’d actually find that at all interesting would be so limited that I’d be wasting my time.  Still, at least I thought about it.

EDIT: Due to popular demand (okay, one person, yay Phill), here are some screenshots of my current OpenTTD game.  I’ve hidden the trees to make the track a little clearer.

[View with PicLens]

And yes, I am a geek.  Thank you for noticing.

Some of you may remember that a while back I spent a week creating a Lego ‘Tumbler’ (from the film Batman Begins), with working suspension and steering.  That was a technical challenge, but I managed to pull it off eventually.  I even made a couple of videos of the progress.  Since then it’s sat quietly on top of the unit in the lounge, silently gathering dust and being generally forgotten.  Until recently I couldn’t bear it any longer, and just had to start thinking about the next version.  Yes, not satisfied with a Lego Tumbler that has working suspension and steering, now I want to put motors in it too.

This presents several problems, however.  The addition of two chunky motors (one for forward/backward motion, one for steering) will add a significant amount of weight to the model, and the suspension is already struggling to cope with the weight as it is.  So I am having to look into better, more effective ways of setting up the suspension, and generally putting the rest of the model on a diet.

At the front of the car, the setup is especially complicated, because it doesn’t use a conventional steering rack.  Just take a look at the original Tumbler and you’ll see just how odd it is.  Squeezing a comparative mechanism into something much smaller is something of a challenge, and although I managed it last time it was a little crude in places, and I’ve been thinking about alternatives.  From looking at various pictures and the bonus DVD I can see that the actual Tumbler uses a system that would actually be pretty much impossible in Lego, simply because of the amount of space it would take up – it works really well, but the Lego components are just too large relative to the wheel to accommodate that approach.  I’ve done a lot of mental experimentation (which is quite difficult without having the Lego in front of you), and pretty much concluded that my previous method will probably still be the most effective, I’ll just have to refine it.

At the back of the car things are equally complicated, though not because the setup itself is difficult.  People have been making cars with suspension for over a hundred years, so it’s not actually something that’s technically complex.  My problem is that Lego likes to be at right angles, not arbitrary angles to cope with pieces moving in an arc.

The problem derives from the combination of needing each wheel to be sprung, preferably independently, whilst still being connected to the engine so as to be powered.  I have done much research on the various different suspension techniques used in real life, and most of them are actually quite difficult to reproduce faithfully in Lego.  The simplest form of rear suspension is the leaf spring, which works really well in lorries and heavy vehicles.  But Lego doesn’t do leaf springs.  It has coils.  I can’t use a proper independent suspension system because I don’t have enough universal joints to connect the wheels to the differential.  A fixed axle is good and simple, but only reliably works in Lego when both wheels are going up and down at the same time – having the wheels going up and down independently causes alignment problems because Lego doesn’t like odd angles.  Trailing arms are out of the question, as are multi-link, A-arm, and MacPherson struts, for much the same reason.

Don’t get me wrong, suspension is possible with Lego – I’ve done it many times before very successfully.  It’s just a matter of choosing the right setup for this particular application, where space and weight are limited.  I may have to resort to some ‘fudging’ or using a limited style of suspension, which would be a shame, but at the moment I’m struggling to see an alternative.  I’m hoping it will all become clearer once I actually get the Lego out and start fiddling.  Ellie is at back at work starting tomorrow, so I’m planning on taking over the lounge each evening next week and see what I can do.  It’ll be shame to take apart the old model, but it needs to be done, and it’ll no doubt be even more satisfying to get a proper motorised version completed!

As with last time, I’ll put photos up at some point to document the progress.  And since the technical aspect is so important, I’ll try to take some close-up photos of the mechanisms for those as geeky as me who like such details.  I’ll also need a good supply of tea to get me through…