[img]i/expressions/face-icon-small-shocked.gif[/img] ummm[img]i/expressions/face-icon-small-shocked.gif[/img][img]i/expressions/face-icon-small-shocked.gif[/img][img]i/expressions/face-icon-small-shocked.gif[/img][img]i/expressions/face-icon-small-shocked.gif[/img][img]i/expressions/face-icon-small-shocked.gif[/img]... Bryce.. I have to inform you that we cannot prove consistant acceleration over the last 1/8.. as shown by calculating the times. accelleration tapers off drastically after 1000 feet in The US Army car anyway..

 

Bryce.,. Is everyone in michigan so aggressive about a point? you aint related to M4L? or Blackballed? or anyof them fella's in the Michigan threads?

 

Top Fuel Dragster Acceleration Data
Possibly the above link could help in the calculations. as you cans see its not totally linier. there is a break point to where it tapers off.. Im gonna find some Data logging for american Topfuel

 

I didn't prove the acceleration is constant by using times. I used force equations to determine the acceleration is constant. Look again at the equations. What I have seen by browsing the Dragster websites is in fact, the dragster groupies haven't got the slightest idea how the dragster accelerates through the quarter mile. Furthermore, it is extremely difficult for even the dragster to even determine its own times and speeds at anywhere on the track.

LOL.. that is the reason that no one knows the answer. Even more enlightening is the vauge references to OVER 8000 HP. It occurs to me that even the engine builders have not figured out how to put a number on their own engines!! The problem is that the engine partially self destructs in 4.5 seconds. So running for any length of time on a dyno is impossible.

What the engine builders need is to have a professional dyno manufacturer design them a dyno so they can characterize the engines they build withing the 4.5 seconds alloted to run the engine.

 

I hear ya bryce.. Its seems rather hush hush amongst the drag community.. but i'd venture to say most the cars have data loggers in them and know exactly what was goin on the whole run. from oil pressure to fuel consumption to engine/exhaust temps to speed and time and bla bla bla. If it was my car I know i would be gettin Data from every run trying to figure out where i can make up time.. and if i wanna do it.. You know i aint the first bird around to think that technology can improve the times.

 

Quite frankly, the graph for the top fueler shows a very constant acceleration with a single break point near the 1/8th mile point. Thanks.. you just proved my point!! However, I have a fundamental problem with using a GPS as a measurement device. This data does not support other data on the web that shows much more non-linearity in the first 1/8 th mile. The data I find on the web indicates initial acceleration of about 6 g at the starting line. (see the Tony Schumacher website). Futhermore, the average acceleration to 100mph is 5.4 gs. The average acceleration in the first 1/8th is 4gs and the average acceleration in the last 1/8 th is 2 gs.

Sorry, but this data has a problem. And it wouldn't be the first time someone has a measurement error, However, it supports my earlier statement that measurement of the top fueler is very difficult.

 

I see what you are saying. The problem comes from the speed measurement. You cannot calculate it from GPS which is only an average calculation. You cannot calculate it from the rear dragster wheels because they are spinning some of the time. You cannot calculate the speed from the front tires, because they are in the air much of the time. It is a real problem for the dragster to calculate its own speed. It seems to me, the only valid measurement is an acceleration from an accelerometer. From the acceleration you can get an estimate of speed by integration.

 

Maybe we need to invent a device that can log the physical data from the asphalt? a 5th wheel perhaps?Maybe laser tracking similar to whats used in a laser mouse?

I dunno.. i just can't buy that these friggin big time drag teams aint got more sophisticated data.

 

LOL.. if you saw how these guys control the dragster.. using 30 point timing curves on the engine to control HP. Mechanical control of the slipping clutch. It is clearly a art. One problem is that the NHRA does not allow them to use an onboard microprocessor to control the clutch or timing. Furthermore, if they overrev the engine past 8250 rpms, an NHRA dictated MSD electronics retards the engine timing to reduce HP.

I watched a top fuel drag race on ESPN this past Sunday. What is clear is that if the guy does not get the controls right, one of two things happens.. either the dragster fails miserably because it spins its tires too much or it makes a quite good run.

A top fueler has the interesting problem that it produces more HP than it can put through the tires. As a result, it does not accelerate anything like a normal car. A normal car has an acceleration curve that flattens to zero out at high speed. At top fueler just keeps increasing in speed. I think this is the point most people do not understand.

 

I just did a search on the web. It seems that they way they can calculate speed is by measureing acceleration as I pointed out above. It seems there are nice packages that make this calculation for you. What is needed for a top fueler is a high bandwidth accelerometer that they can hook up to their data acquision equipment. The higher the sample rate, the more accurate the acceleration, the more accurate the speed.