Re: 1/2 Mile shootout today!
 

Well, on the flip side, is it impossible to average the same speed (in the trap) twice? IMPOSSIBLE?? I dunno, Al. But, maybe you shoulda bought a LOTTERY TICKET last Sunday!:p

Quite possibly; depending on acceleration through the trap: The greater the acceleration between the gates, the greater the distance/time value is going to vary from the peak speed. Narrowing the distance between the gates gets closer to the top speed, but errors internal to the equipment increases the ambiguity of the results too.

Bottom line: Regardless of the trap length (distance between the start/stop gates), neither the existing nor proposed additional length guarantees there won't be two or more identical speeds. IT COULD STILL HAPPEN, in other words.

Re: 1/2 Mile shootout today!
 

I know they would make me clean up the black marks; like when I was in High School!!!!
:(

Re: 1/2 Mile shootout today!
 

Paul,

There were several cars on both days where the exact same speed was recorded for sequential runs. That's what makes it very suspicious. From my point of view, I want to know what the speed is AT THE LINE, not an average speed.

Re: 1/2 Mile shootout today!
 

Yeah, I didn't know there were several sequential runs with the same speeds. You're right. That does raise an eyebrow, doanit!?:confused:

I hear ya, far as speed at the line vs. average. But, as long as speed = distance/time, the only way to approach the pinnacle is by narrowing the distance.

However, practically speaking, errors introduced by the chronograph is typically a fixed value - a certain amount of fixed time error (related to signal pulse response detection/lag and timer clock frequency, etc.), and not a fixed percentage of the calculated value. So, the shorter the time between gates, the greater the ambiguity is, due to that fixed measurement accuracy error inherent to the measuring device.

That's where a Doppler radar differs in its approach. The speed is determined by the frequency shift in the arriving pulses compared to the transmitted pulses. And, with "peak hold" software, the peak speed could be recorded regardless of where on the track it occurred. Just a thought.

Re: 1/2 Mile shootout today!
 

Paul,

After all this is a TOP SPEED event, so it would seem to me that other organizers have figured out the equipment thing long time ago. I think the Doppler would be best approach Have redundant guns.

Re: 1/2 Mile shootout today!
 

Well, I don't know that just because this is a TOP SPEED event one could assume "somebody" figured it all out: e.g., did (Blake?) not suggest using a longer trap (i.e., wider gates)? That indicates to me they are still proposing using a chronograph - which is still distance/time = average.

Yes. Dual "speed guns" would solve all this trap stuff. And, if we really want NASA-esque accuracy, a third radar used as a tie-breaker could be employed. And, straddling the finish line with the gates would also mitigate most(?) of the error introduce by acceleration through the gates.

And, what is not considered here is a measuring device needs to be able to measure (time in this case) to a factor least 10 times greater resolution than the least significant digit. In other words, if mph is measured to 1/10,000 seconds, the measuring device must be able to measure to 1/100,000 in order to round up to the next nearest 1/10,000th.

An even bigger question might be: [I]is the resulting mph measured or extrapolated (mathematically) by virtue of the values considered?

If legitimately measured, fine; we have a legitimate value. But, if it is an extrapolation, the result is invalid.

*For example: Given the integers 13 ÷ 7 = 1.85714285714 (to "only" 11 places). If the measurement device is only capable of measurement accuracy to integer level (whole numbers), then the decimal fraction (numbers to the right of the decimal) is bogus.

In other words, if (some chrony) was only capable of measuring to 1/100 (rounded to 1/10th) then the second, third, fourth, etc. significant digit on up are meaningless.

At some point this gets way to serious for the average driver (me included). But, at what point is the limit for practical accuracy? Opinions vary, I'm sure.

Paul

Re: 1/2 Mile shootout today!
 

Hey Paul
I didn't know you speak Greek LOL
You said chronograph in Greek chrono means time and graph or graphee means write put them togather and you get write time or vice versa.

Paul,we just have to baptize you and you'll be an official Greek :)

Pete

Re: 1/2 Mile shootout today!
 

Paul,

Do you understand what Pete means by "baptizing" you Greek. It's sorta like somebody saying "You sure have a puurty mouth." BAAAAAAHHHHHH!

Re: 1/2 Mile shootout today!
 

LMFAO
Too Funny
Dom,now that you mention it Paul sure does have a puurdy :censored:

Pete

Re: 1/2 Mile shootout today!
 

I'm flattered, Pete. I never knew you noticed!:p

Pete... With the thought of a "Greek baptism" in mind, I'll bet I could run the half mile as fast as my Z will go!

How-some-ever...Speaking of baptizing n puurdy :censored:, I saw that movie too! But, maybe you should know that my vast experience with my personal chronograph is the one I use to measure muzzle velocity pertaining to that "other hobby" of mine.... LOL!