Oh c'mon, that last one must be a scene from star wars or something.

Quote from STROBE :

Jeez, that's not much of a pot hole.

I never said it was huge. Still knacked my tyre though, didn't it?

Incidentally, as of this morning, pot hole has been filled.

Quote from danowat :

Compulsary retests for EVERYONE, every 5 or so years is the only way to go.

Definitely agree there.

Quote from danowat :

The vast majority of BMW drivers don't indicate.

The vast majority of drivers don't indicate.

Ah yes, I have played with that method before.

The relaxation length stuff goes even more horribly wrong at low speeds though, and instead of a vibration, you end up with your car sliding side to side with a magnitude of the relaxation length. I seem to remember having troubles getting the damping to work correctly, I'll have to have another play with it at some point, see if I can get that method to work.

Quote from Shotglass :

hm handt thought about that but then again you cant expect a model that based around slip to work when there is none

Yes, you need a separate low speed solution, or you need to add damping, or a combination of the two.

Pacejka suffers from the same thing though, the cornering and braking stiffnesses act like springs and the car will just oscillate between the two slopes while stationary, and never settle as there is no damping.

Merged, thanks JazzOn

Any spring-mass-damper can oscillate or become unstable, I don't see how any tyre model would be immune to this.

Quote from DevilDare :

The Russians have already created a reconstruction.

You are kidding. That's an awful animation. Thought I do get the idea (i.e. it crashed, which I thought was obvious anyway).

Quote from jasonmatthews :

After discussing the numbers with the track owner, he said he wouldn't like it to go over 40 people, so sorry for the confusion.

Is that 40 racing or 40 attending?

How much track time are we all expecting? There was plenty last time with teams of 3 but larger teams I'd like to know what the expected track time is reducing to. Thanks.

Well that is the general idea, but the tyre modelling in VHPA is comparatively simplified (there are no slip curves, for example, it's just not needed unless you want to drive it in real time).

Yeah maybe we don't have it so bad.

mrodgers - Jakg hit the nail on the head, but I was coming across the road, not cornering, so I was doing the 30mph limit. A big wide pothole I wouldn't mind so much, it was the sharp edge that got me. Although Becky's suggestion might have some merit. I'm usually too worrying about how the things work when they're new, let alone when they're damaged.

[RF]-art555 - are they a recent photos? Is that the typical sort of age of cars you have over there?

At least I've got my new tyres ready and waiting to go on tomorrow morning: http://bmp.thefloatingwidget.n ... /Tyres%20to%20go%20on.JPG
And I've had a good stab at cleaning up my wheel while it's off the car. Lots of stuck on dirt though that won't shift easily and I don't want to scratch the wheel(s) up getting it off: http://bmp.thefloatingwidget.n ... yre%20to%20come%20off.JPG (doesn't really show up in the photo though)

I'm not sure what you're asking there?

Big on the outside, bigger on the inside? And besides, even if the house is full, take a tent and kip in the garden. Or in a car. Or that really long driveway of his. Or the trees. Or the street. Or stay up all night. Lots of possibilities.

Ah yes, I didn't post the photos:

Close ups:
http://bmp.thefloatingwidget.n ... s/Pothole%20-%20above.JPG
http://bmp.thefloatingwidget.n ... le%20-%20with%20ruler.JPG
http://bmp.thefloatingwidget.n ... s/Pothole%20-%20depth.JPG

Show location (only useful if you're local):
http://bmp.thefloatingwidget.n ... le%20-%20from%20north.JPG
http://bmp.thefloatingwidget.n ... le%20-%20from%20south.JPG

Quote from Nikn :

The coefficient's are from pacejka's book (http://www.flipkart.com/book/t ... namics-pacejka/0750669187) but four of the coefficients were missing so I guesstimated those. The data they are based off of is empirical but judging from the curves they only measured slip angles up to about 8 degrees (doesn't capture falling off of force at higher slip)

Funny, I have graphed those coefficients and there is indeed fall off (far more longitudinally than laterally, as you would expect). The example tyre doesn't peak in slip until 14 to 15 degrees so I don't see how you came up with your 8 degrees figure.

Edit: Here's the graphs: http://www.vehicle-analyser.com/p96_tvd_example.PNG

Juls - I would argue, if you're not familiar with either empirical or brush models, than empirical models are at least easier to work with, as each part of the equations directly relates to part of the curve in certain circumstances, and it's easy to see which parts you need to replace if you don't like how part of an empirical model works.

I only ask as the car felt fine until then, and in fact I had even been in the corner for a second feeling understeer before the rear broke loose. Hmm, makes me think, maybe there was something on the roundabout that cut the tyre? I'd imagine under hard cornering the top part of the sidewall where the cut is would probably be on the ground.

I think I need somone with a high speed camera to film me acting like a boy racer at a roundabout so I can have my very own slow-motion tyre deformation video.

Right well I've taken a few photos next to a foot long ruler, so the size, depth, and location of the pothole is unmistakeable. I didn't bring the usb cable with me to work so you'll have to wait until I can get them off tonight to see.

As for my flat tyre event, I was wondering, is it possible the tyre managed to stay airtight after the pothole, but then opened up during the hardish left turn at the roundabout, as the sidewalls began to stretch and tuck under?

Lost the front bumper? Sounds like a bit of a serious pothole!

Close up tyre photos (click for full size versions):


Thanks for the links Jakg. Looks like it might be too much hassle to consider claiming if I've a slim chance of getting anything. I'll still photograph, measure and report the pothole though. And make sure I avoid it in future!

Was driving to work this morning in the usual fashion, came up to the roundabout on to the dual carriage way, when suddenly wee, lots of (very gentle and progressive) oversteer turning left on to the roundabout. Thought that a) has never happened on that roundabout before, even if the surface is a little bumpy and b) was all so smooth it feels just like low tyre pressure.

Indeed the last couple of miles of the journey did have a floaty feel, but I took the car hard into a right turn (edging up to the limit) and all seemed normal.

Once parking outside work and inspecting the right rear, the obvious issue was confirmed, I had a flat tyre.

Closer inspection, however, revealed a nice two inch long gash into the sidewall. Bah. No repairing that. Although in fairness the tyre was due for replacement anyway, so it's not really a wasted tyre.

I can only think it was the bad pot hole I hit between the last set of lights and the roundabout of oversteer. The cut is quite near the top of the sidewall when at the top of the tyre, so close to the road.

I'm going to take a photo of the tyre tonight and try and get a snap of the pot hole tomorrow lunchtime (while all the time nannying around on a 50mph space saver).

What's my chances of getting the council to refund my new tyre cost? I've heard if the pothole is large and deep enough it should be filled, thus they are liable for any damage caused? Any truth in that?

I can't see anybody objecting to more spectators. When are you considering travelling?

Websites are down?