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I just bookmarked them and a weather site that has humidity and the Barometer readings.
The DA won't be exact but close enough for the avg guy or girl.
Thanks very much, Pitman. . . I just downloaded the app and it seems to work well. Funny, the DA when I ran for last Saturday was calculated at 49 ft, and just for giggles I put in the data for corrections - and my corrected time was a hair slower...? I thought anything above sea level should show a lower corrected # and a negative DA will always net a higher time "at sea level" . . .?
Anyone know of a good iPhone app or website? I'm trying to find a simple way of figuring out DA when at the drag strip.
http://airdensityonline.com/ go to free weather for tracks pic your track, add as a bookmark to your phone this one tells the da without adding any data
Last edited by dennis50nj; Jan 29, 2013 at 05:07 PM.
Those are all good sources (as pit-man noted) to get a general 'in the ballpark' idea of the DA but of course the ONLY way to get a truly accurate reading is with a well calibrated weather station (hand held device) used directly at the track, at the starting line actually of when/where you're making a particular pass.
I've seen some online sources (some of which might get their data from nearby airports or office buildings with meters located 30-40 or more feet in the air etc.) differ from the hand held units by as much as 700 feet ...but it's usually only about a 200-300 foot difference.
Those are all good sources (as pit-man noted) to get a general 'in the ballpark' idea of the DA but of course the ONLY way to get a truly accurate reading is with a well calibrated weather station (hand held device) used directly at the track, at the starting line actually of when/where you're making a particular pass.
I've seen some online sources (some of which might get their data from nearby airports or office buildings with meters located 30-40 or more feet in the air etc.) differ from the hand held units by as much as 700 feet ...but it's usually only about a 200-300 foot difference.
Yeah, I figured anything easy would be a little off. I'm guessing the hand held technology isn't cheap though...?
The Dragtimes site has 2 issues to overcome.
It doesn't have accurate elevations for all the tracks, compared to GoogleEarth which has accuracies within 5' of surveyed Geo markers.
The weather data is only once per hour and is sourced from the closest large airport which could be many miles away. Fortunately, the Sacramento track's closest weather station is at Mathers AFB about a mile away.
When a handheld is setup well and used properly it can give you the best info at a low cost. I prefer to keep mine in the pit area, since I detect as much as a 5* difference in the staging lanes or start line.
The ultimate solution is having the track install a quality unit with the sensors about 2' above ground between the lanes at the 1/8 mile mark. Then print the results on the timeslip, including the DA and the sea-level adjustment for N/A cars.
The Dragtimes site has 2 issues to overcome.
It doesn't have accurate elevations for all the tracks, compared to GoogleEarth which has accuracies within 5' of surveyed Geo markers.
The weather data is only once per hour and is sourced from the closest large airport which could be many miles away. Fortunately, the Sacramento track's closest weather station is at Mathers AFB about a mile away.
When a handheld is setup well and used properly it can give you the best info at a low cost. I prefer to keep mine in the pit area, since I detect as much as a 5* difference in the staging lanes or start line.
The ultimate solution is having the track install a quality unit with the sensors about 2' above ground between the lanes at the 1/8 mile mark. Then print the results on the timeslip, including the DA and the sea-level adjustment for N/A cars.
Tom that would be a very good solution, but atco cant even put the right time on the slips when daylight savings time kicks in, let alone keep a weather station calibrated remember forum member siffert use to use google earth and say atco was downhill and the elevation was wrong, if you have ever been to atco and know the layout you can clearly see google earth is wrong, that could be 5+ or 5- on each end plus could be meters off on the longitude and latitude not matching the pictures, i can clearly see the return and pit area is higher then the track surface at the start but levels toward the end
The ultimate solution is having the track install a quality unit with the sensors about 2' above ground between the lanes at the 1/8 mile mark. Then print the results on the timeslip, including the DA and the sea-level adjustment for N/A cars.
The best one by FAR was the old "TAG" weather station that myself & a few others have at the track...Sad day when he stopped selling them (divorce I think) but mine is accurate to within .02
Ralph and I think Ellis also have them.. There is another one called "ProAir" Or something like that but it costs about $400 or close to that....
Free iPhone app called AutoDens. It works with your GPS. Awesome app.
I saw that one too but it didn't have any ratings so I skipped it - but now that you rated it here, I downloaded it This will be fun - most likely going back to the track on Saturday in search of an 11-sec. slip and I'll try all the different DA readers and see how close they are.
I saw that one too but it didn't have any ratings so I skipped it - but now that you rated it here, I downloaded it This will be fun - most likely going back to the track on Saturday in search of an 11-sec. slip and I'll try all the different DA readers and see how close they are.
Yeah, it grabs the data from the closest airport, I believe. Works great at PBIR in West Palm because its close to the track.
2020 Corvette of the Year Finalist (track prepared)
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Originally Posted by SeeFiveOhFun
I saw that one too but it didn't have any ratings so I skipped it - but now that you rated it here, I downloaded it This will be fun - most likely going back to the track on Saturday in search of an 11-sec. slip and I'll try all the different DA readers and see how close they are.
The problem with those websites is they typically only update once an hour which is fine if you're just trying to get a ballpark idea of what the DA is but not so much if you're trying to figure out a dialin for bracket racing. I've used the Kestrel and on more than a few occasions been able to predict my ET to within .005 seconds and sometimes even less than that.
The problem with those websites is they typically only update once an hour which is fine if you're just trying to get a ballpark idea of what the DA is but not so much if you're trying to figure out a dialin for bracket racing. I've used the Kestrel and on more than a few occasions been able to predict my ET to within .005 seconds and sometimes even less than that.
Chris,
I wish I had your money. Lets see....free vs. $256.
Just sayin
Jeff
The problem with those websites is they typically only update once an hour which is fine if you're just trying to get a ballpark idea of what the DA is but not so much if you're trying to figure out a dialin for bracket racing. I've used the Kestrel and on more than a few occasions been able to predict my ET to within .005 seconds and sometimes even less than that.
Thanks Chris. Right now I'm just trying to get used to the car and see how fast I can go with all the stock parts (sans the run flats!). And often when we start talking 1/4 mile times, the question comes up of what the DA was so I'm just looking for a good way to ballpark it.