time/distance calculation

[Bigmouse]

Anyone any good at working out time and distance calculations? I tried but just gave myself a headache. I was in a real close race on Sunday at the National Finals and would be interested to find out just how close it was at the line.

I crossed the line at 154.55; Mark crossed the line at 155.13. The ticket shows just .0463 difference at the line. Not sure whether the times are valid or not but they were 8.9792 to a 8.9099.

[Tet]

Bigmouse said:

Anyone any good at working out time and distance calculations? I tried but just gave myself a headache. I was in a real close race on Sunday at the National Finals and would be interested to find out just how close it was at the line.

I crossed the line at 154.55; Mark crossed the line at 155.13. The ticket shows just .0463 difference at the line. Not sure whether the times are valid or not but they were 8.9792 to a 8.9099.

3.21m, or in old money, 10'6". I'd need to know who crossed the line first to tell you for sure, but since your terminal speeds are so similar, it really doesn't make much difference here (only 30mm or so -- just over an inch).

[Bigmouse]

Tet said:

3.21m, or in old money, 10'6".

wow, as much as that? I thought it was much less, it certainly seemed like a lot less at the time. Cheers for that Tet

[Slinky]

I'm sure AM will release the stats to Eurodragster this week, they'll have the distances listed on them chap..

[Eurodragster.com]

There is a spreaddy available which works out win margins.

E-Mail me at my Eurodragster.com address for a copy, apart from Ray who'll find one when he next gets to the office.

[AM]

Tet said:

Bigmouse said:

Anyone any good at working out time and distance calculations? I tried but just gave myself a headache. I was in a real close race on Sunday at the National Finals and would be interested to find out just how close it was at the line.

I crossed the line at 154.55; Mark crossed the line at 155.13. The ticket shows just .0463 difference at the line. Not sure whether the times are valid or not but they were 8.9792 to a 8.9099.

3.21m, or in old money, 10'6". I'd need to know who crossed the line first to tell you for sure, but since your terminal speeds are so similar, it really doesn't make much difference here (only 30mm or so -- just over an inch).

Tet's close enough for me not to argue with him, and if I did I guess I risk being reversed over

However, any calculation is only ever going to be approximate as the speed at the finish line is not actually known. The speed displayed is an average over the last 66 feet so cars/bikes are almost certainly either still accelerating or decelerating through the speed trap.

The formula I use is to convert both speeds to fps and take an average, then multiply it by the time difference.

Edited by AM on Monday 1st October 23:20

[Tet]

AM said:

Tet's close enough for me not to argue with him, and if I did I guess I risk being reversed over

:-) Only if you're standing in the wrong place. Maybe I should get some wing mirrors put on the car...

AM said:

The formula I use is to convert both speeds to fps and take an average, then multiply it by the time difference.

Just using the speed of the losing vehicle should give a better approximation. After all, the terminal speed of the winner doesn't affect how far back the loser is at the time the winner crosses the line, but the loser's terminal speed does give a reasonable indication of the MOV[1]. This generally isn't an issue in the heads up classes like Ray's race. But the ET and fixed index classes tend to play more top end games, and the winner's speed can be significantly down -- enough to throw the average off by a noticable amount.

[1] In distance terms, and of course subject to your caveat about in only being approximate.

Edited by Tet on Tuesday 2nd October 00:21

[AM]

AM said:

Tet said:

Just using the speed of the losing vehicle should give a better approximation.

Depends which question you want answering.

How far behind was the loser when the winner crossed the finish line ?
Or
How far ahead was the winner when the loser crossed the finish line ?

Personally I think the winning margin is how far behind the losing car is when the winner crosses the line, but this is impossible to measure exactly in terms of distance.

I don't need to tell anyone here there's around 500 bazillion variables in drag racing, the only thing we can measure exactly is the ET. The speeds are an average over 66 feet so the distance difference has to be measured using an average of both vehicles speeds.

I agree with your point about ET classes playing silly buggers at the top end, but it could be either car doing it so it negates the argument.

Edited by AM on Tuesday 2nd October 00:58

[KP1]

I have another question about the timeslips from Santa Pod. On the timeslip it says 1000 ft but on eurodragsters timing data it says 990 ft. Wich one is correct?

[Eurodragster.com]

I know it is actually 990 feet on some timing systems (which would tie in with 330 and 660). AM will doubtless confirm which it is at SPR but my guess is 990.

[AM]

It is actually 990ft (3/4 track).

I think the reason it's called 1000ft is laziness, it's easier to say "thousand" than "nine hundred and ninety". It's then been written into the software as 1000ft. That's my theory anyway, though I'll check with Steve when he's back.

[Time Machine]

AM said:

Depends which question you want answering.

How far behind was the loser when the winner crossed the finish line ?
Or
How far ahead was the winner when the loser crossed the finish line ?

Personally I think the winning margin is how far behind the losing car is when the winner crosses the line, but this is impossible to measure exactly in terms of distance.

Interesting viewpoint, and possibly one worth looking at.

Now of course we need a spreadsheet listing all 3 possible methods (How far behind was the loser, How far ahead was the winner, average of both) so we can see what the variation is.

As to which question most accurately represents what people want to know (by what distance was that race won/lost) - the race is over (insert caveat regarding red lights, boundary violations, breakouts and other infringements) when the first car crosses the line so the question which needs answering is "How far behind was the loser when the winner crossed the finish line?"

This means that the start of the window of time you are interested in is when the winner crosses the line and the end is when the loser crosses the line. This makes speed of the winner irrelevant and all you need to know is the time difference and the approximate speed of the loser:

Speed = Distance / Time, therefore Distance = Speed x Time.

To account for units of measurement:

(Distance in inches) = (Speed in MPH) x (Time in Seconds) x 17.6
(Distance in feet) = (Speed in MPH) x (Time in Seconds) x 1.4667
(Distance in centimetres) = (Speed in MPH) x (Time in Seconds) x 44.704
(Distance in metres) = (Speed in MPH) x (Time in Seconds) x 0.44704

So using the above numbers

Distance = 154.55 x 0.0463 x 17.6 = 125.94 inches = 10.49 feet = 10 feet and 6 inches = 3.20 metres


Now as discussed statistical anomalies caused by the approximation of speed may mean taking an average of the two is more accurate, but theoretically the above method is correct. The closer the two speeds (the lower the closing velocity) the less variance there will be, but if (for example) a fuel car snaps a blower belt and idles up the track while the car in the other lane is really late off the lights and they happen to cross the line almost at the same time, you get the following:

Lane 1: 50mph
Lane 2: 250mph

Lane 2 wins by 0.01 seconds.

Method 1:

Distance in centimetres = 50 x 0.01 x 0.44704 = 0.22 m

Method 2:

Distance in centimetres = 250 x 0.01 x 0.44704 = 1.12 m

Method 3:

Distance in centimetres = (50+250)/2 x 0.01 x 0.44704 = 0.67 m


Obviously method 3 always gives the average of methods 1 and 2. If (is fairly likely) 50 mph is a good approximation of a car idling up the track, method 1 is far more accurate. The only way to know for sure would be an awful lot more photocells or a high speed camera and a ruler painted on the track :-)

[NitroWars]

Andy, when do you get your anorak back off Martin?

[AM]

Time Machine said:

Now as discussed statistical anomalies caused by the approximation of speed may mean taking an average of the two is more accurate.......The only way to know for sure would be an awful lot more photocells or a high speed camera and a ruler painted on the track :-)

Those 2 points mean everything else you said is speculation, there's a lot more theory than reality. Without knowing the exact speed of the vehicles any calculation involving distance is going to be approximate, hence using the average speed gives the best approximation.

NitroWars said:

Andy, when do you get your anorak back off Martin?

Nah, he's just gone out and bought one of those pak-a-mac things That said, fancy a job on the timing crew Martin ?

[Barry B]

AM said:

Nah, he's just gone out and bought one of those pak-a-mac things That said, fancy a job on the timing crew Martin ?

Or what about depping for Vorderman on Countdown when she's off making tv for advertising loan sharks ?

[NitroWars]

Barry B said:

AM said:

Nah, he's just gone out and bought one of those pak-a-mac things That said, fancy a job on the timing crew Martin ?

Or what about depping for Vorderman on Countdown when she's off making tv for advertising loan sharks ?

Never heard of advertising loan sharks. Do they only give loans to make adverts? I think it is disgusting that somebody as well known as she is for what she is good at is doing those adverts. A lot of "mugs" will be caught out as she gives some credibility but the rates are phenomenal. Still I suspect she was paid well (as if she needs it)!

Edited by NitroWars on Tuesday 2nd October 13:45

[Barry B]

Note to self: no matter how much of a rush you're in, read the bloody post before you send it, that way you would spot the word 'commercials' was missing !

[Tet]

NitroWars said:

I think it is disgusting that somebody as well known as she is for what she is good at is doing those adverts.

You're not the only one: http://www.moneysavingexpert.com/petition/ 

Personally, I don't have a problem with it. If someone's prepared to take out a loan without reading the small print, and without working out how much it's going to cost them, purely due to the fact that Carol Vorderman's advertising it, then I'm afraid I don't have much sympathy for them...

[Jon C]

Tet said:

NitroWars said:

I think it is disgusting that somebody as well known as she is for what she is good at is doing those adverts.

You're not the only one: http://www.moneysavingexpert.com/petition/ 

Personally, I don't have a problem with it. If someone's prepared to take out a loan without reading the small print, and without working out how much it's going to cost them, purely due to the fact that Carol Vorderman's advertising it, then I'm afraid I don't have much sympathy for them...

Dont start me....

Bloody woman.

Those ads are only ever on in the afternoon, funny that.

Targeting morally bankrupt services to financially illiterate saps who are, by definition, not at work in the afternoons and therefore by definition unsuitable candidates for credit.

They are all as bad as each other. I had a real problem watching Purple Loans involvement in Drag racing, to be honest.

A pal of mine who is a senior partner in a major accountancy firm once told me that the perpetrators of those high pressure targeted adverts would have been looking at custodial sentences for irresponsible selling of credit as recently as ten years ago.

And she only got a bloody third, as well.

[AM]

Nice norks though