sbindy
Steve B
For most people, the term "Humidity" should equate to how much water is in the air. In real practice, that's just not the case. Making tuning calculations based on Humidity can give you misleading results because Humidity only gives you a vague idea of how much water is in the air, and just how dense the air actually is.
I worked in Professional Drag Racing for 15 years, and each team had a weather station in their trailer that gave constant updates as to the changing conditions. One of the variables that we used every single run was the "Grains of Water per/lb.". That told just how much water was in the air, and we would adjust our timing advance to compensate, along with the blower overdrive, compression, and nitro percentage to adjust for the temp change and the density altitude.
http://www.wallaceracing.com/adi.php
This link will allow you to put in the Temperature, Pressure, and Humidity to give you a Density Altitude and Grains of Water measurement. The Grains will range from a Low of 0, and a High of 160. In all my years of racing, even under the best of conditions I dont think I ever saw it at less than 10, and only ever saw it over 160 once, and you didnt want to be anywhere outside when it was that bad out.
50% Humidity doesn't sound that bad, so put these numbers in.....29.02 pressure, 90 degrees, and 50% Humidity. Those were the conditions today at the race in Norwalk Ohio. Then put in 92 degrees, 28.98 pressure, and 63% Humidity and compare the numbers. In case you dont want to go to the site and figure it, here's the answers. The difference in Density Altitude between the 2 is just over 200ft., and the Grains of Water went from 141 to 148, which really isnt that much of a change, but most people would think a 13% change in Humidity is a sizeable amount. Thats why Humidity alone is misleading.
What these numbers will mean to the changes you make in the tune of your rifle, only you will be able to figure out by comparing the changes in conditions, the changes you make, and the results you get. However, once you get a handle on the trends and get repeatable results, you will be able to use them anywhere.
I worked in Professional Drag Racing for 15 years, and each team had a weather station in their trailer that gave constant updates as to the changing conditions. One of the variables that we used every single run was the "Grains of Water per/lb.". That told just how much water was in the air, and we would adjust our timing advance to compensate, along with the blower overdrive, compression, and nitro percentage to adjust for the temp change and the density altitude.
http://www.wallaceracing.com/adi.php
This link will allow you to put in the Temperature, Pressure, and Humidity to give you a Density Altitude and Grains of Water measurement. The Grains will range from a Low of 0, and a High of 160. In all my years of racing, even under the best of conditions I dont think I ever saw it at less than 10, and only ever saw it over 160 once, and you didnt want to be anywhere outside when it was that bad out.
50% Humidity doesn't sound that bad, so put these numbers in.....29.02 pressure, 90 degrees, and 50% Humidity. Those were the conditions today at the race in Norwalk Ohio. Then put in 92 degrees, 28.98 pressure, and 63% Humidity and compare the numbers. In case you dont want to go to the site and figure it, here's the answers. The difference in Density Altitude between the 2 is just over 200ft., and the Grains of Water went from 141 to 148, which really isnt that much of a change, but most people would think a 13% change in Humidity is a sizeable amount. Thats why Humidity alone is misleading.
What these numbers will mean to the changes you make in the tune of your rifle, only you will be able to figure out by comparing the changes in conditions, the changes you make, and the results you get. However, once you get a handle on the trends and get repeatable results, you will be able to use them anywhere.
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