It's Not Big, and It's Not Clever...

ThePrisoner · Post by **ThePrisoner** » Sat May 19, 2007 4:29 pm

Good job I don't own a V6 otherwise i'd have been in even more trouble!

**In no way do I condone speeding. The purpose of this post is to educated drivers about the danger of speeding by using my own personal experience. I have paid a fixed penalty notice for this offence, and therfore can use the photos for whatever purpose I please.**

Pris.

Post by **DaiRees** » Sat May 19, 2007 4:36 pm

Tut tut!!

I though you were a member of the constabulary

TooT · Post by **TooT** » Sat May 19, 2007 4:37 pm

Oh dear,

They should be out catching real criminals.

(ive got 3 points)

ThePrisoner · Post by **ThePrisoner** » Sat May 19, 2007 4:48 pm

Well I have learnt and am now paying for it, 3 points put my insurance up by £167!

and I got a bollocking at work.

Pris.

Captain Jack · Post by **Captain Jack** » Sat May 19, 2007 5:03 pm

Just out of interest, what was the indicated speed on your speedo? I was doing 80mph when I saw a tw@t with a camera on the bridge on M4. I figure my satnav displayed 76mph so I should be OK....? Or not...?

mjb · Post by **mjb** » Sat May 19, 2007 5:05 pm

oops

Nice "action shot" though...

ThePrisoner · Post by **ThePrisoner** » Sat May 19, 2007 5:07 pm

You'll be fine.

GPS is more accurate speed, as all speedos are out anyway!

That is why the law allows 10% + 2 mph. So if the speed limit is 70mph then you probably will get away with actually travelling at 79mph! That is where the 'magical' 80mph comes from.

However if you travel at anything more than an actual 80mph, then you leave yourselve wide open for prosecution. Different police forces prosecute at different speeds.

Above was in Wiltshire and they prosecute at 82/83mph!

Other forces will vary, I have heard of some prosecuting at 86/87mph.

When I was caught on the occasion above, my speedo was just shy of 90mph and the actual recorded speed was 84mph. (Allowing for when I slammed on the anchors!)

Moral of the story is don't speed! and don't let your speedo ever get above 75mph

Pris.

jameslxdt · Post by **jameslxdt** » Sat May 19, 2007 5:34 pm

i didnt know a D9 was capable of those speeds without something fookin up

ThePrisoner · Post by **ThePrisoner** » Sat May 19, 2007 5:40 pm

jameslxdt wrote:i didnt know a D9 was capable of those speeds without something fookin up

It is capable of a lot more than that trust me, but I wont disclose any more details.

Pris.

turbolag · Post by **turbolag** » Sat May 19, 2007 5:41 pm

Sat Navs not always the best speed indicator, dependent on the type and the algorithm employed to calculate the speed.

The sat nav measures your speed between 2 fixed datum in space, but most take no account of you driving in a curve, ie around the circumference of the earths surface, plus any actual local variations in altitude, so your actual 'ground speed' is always at faster than your 'airspeed', which is what's measured by these toys.

Thats why aviators adopted knots (nautical miles per hour) as their rate of progress between 2 fixed points in the sky could bear little relation to their ground speed - a plane flying upward at 45% will only have a groundspeed of half its airspeed. Its a similar geometrical problem to that faced by sat navs, so they're not as entirely trustworthy as many pundits reckon, though much of the time they probably are more accurate than mechanically driven or governed speedos due to the more consistent digital measurements...but you'd be daft to bet your licence on it!

ThePrisoner · Post by **ThePrisoner** » Sat May 19, 2007 5:43 pm

turbolag wrote:Sat Navs not always the best speed indicator, dependent on the type and the algorith employed to calculate the speed. The sat nav measures your speed between 2 fixed datum in space, but most tke no account of you driving in a curve, ie the circumference of the earths surface, so your actual 'ground speed' is slower than your 'airspeed', which is whats measured by these toys. Thats why aviators adopted knots (nautical miles per hour) as their rate of progress between 2 fixed points in the sky could ear little relation to their gornd speed - a plane flying upward at 45% will only have a groundspeed of half its airspeed. Its a similar geometrical problem to that faced by sat navs, so they're not as entirely trustworthy as many pundits reckon, though much of the time they probably are more accurate than speedos...but you'd be daft to bet your licence on it!

They are more technical than I originally thought! That is quite interesting, and does actually make sense. So the GPS systems they use on ships, must be set up differently, or just the way they record their actual speed?

Pris.

turbolag · Post by **turbolag** » Sat May 19, 2007 6:01 pm

That's as I understand it, from an explanation given by my Dad who is a pilot/engineer/salesman/financier (he sells helicopters for a living).

However, thats the limit of my understanding - I might have an MSc in celestial mechanics, but i'm bu66ered if I can make head or tales of a gas bill!

Good hing that copper wasn't with the taliban, or you'd be pushing up daisies by now (or on Al Jazeera!) - good aim.

Blue406 · Post by **Blue406** » Sat May 19, 2007 6:18 pm

'least you got caught speeding in style

I'll get me coat

mjb · Post by **mjb** » Sat May 19, 2007 7:59 pm

turbolag wrote:The sat nav measures your speed between 2 fixed datum in space, but most take no account of you driving in a curve, ie around the circumference of the earths surface, plus any actual local variations in altitude

Most modern GPS equipment is capable of reporting your position on Earth in three dimensions accurate to about +/-10ft when tracking 6+ satellites which is about what you'd get from 3 satellites if you were in space. Error comes from things like the composition of the atmosphere the signals from each satellite has to travel through to reach your receiver, and the signals bouncing off things, although a lot of GPS equipment/software use algorithms to drastically reduce these errors when given enough signals to work with.

The problem is whether or not the software using the GPS receiver bases its speed calculations on the original 3 dimensional co-ordinates, or if it converts them to 2D first. Thankfully (thanks to a big building and a glass lift) I've actually checked and TomTom records a constant speed when travelling vertically

However, given the distance you're going to travel by car in the 1 second or less the GPS software updates itself, is the Earth's curvature a significant variable? Not even for Hammond... Is travelling on hills going to make your speed read low? Depends on how poor your software is!

Also aviators adopted knots because without modern navigation aids you can't automatically measure distances on a plane, only the amount of air rushing over/under the wings - hence why they use the term 'knots IAS' - Indicated Air Speed. Before the advent of electronic devices in planes pilots had no real way to tell how fast they were going: If a pilot saw 57knots IAS in his cockpit instrumentation but he's head on to a 50mph wind, he could well be on the ground at a standstill... Mind you in those days all you cared about was that there was air moving past the wings so you weren't going to drop out of the air

GPS is a very reliable and pretty accurate system. You've just got to be aware that while your setup might be accurate, it may not be, and you should jump off a tall building while holding your receiver just to make sure!

GeordieBoy · Post by **GeordieBoy** » Sat May 19, 2007 8:36 pm

Get yourself 1 of these: http://www.road-angel.co.uk/new_road_angel.htm
Then when it goes off, hit the anchors.

I'm ordering mine soon. Not that I speed much, but we all do it from time to time.