The above formula is the average line through the plotted points. Using the gross weight of the car and the tested true clutch HP, the lbs-per-HP ratio was derived. (The gear effect was compensated by using a factor to allow for engine and drive line rotating inertia.) Anyway, the car was tested on a quarter-mile to accurately determine the terminal speed at the end of the quarter.
What I would do is test the car with an accelerometer - and several complex equations - to determine the true peak HP delivered at the clutch under accelerating conditions, usually in a gear giving the HP peak between 60 and 90 mph, to make it easier to get consistent accelerometer readings. It was the result of 40 or 50 road and strip tests of many different cars. The constant is 224 not 225, and MPH is calculated by dividing 224 by the cube root of the lbs.-per-HP ratio. That explanation is reproduced below with some minor editing.
Huntington also determined a formula for 1/4-mile elapsed time. Huntington presented his graph for predicting 1/4-mile terminal speed in an article titled Horsepower at the Drag Strip, pages 50-53 in the December 1958 issue of Rod & Custom magazine (thanks go to Earles McCaul for this information). In the 1950s, the late Roger Huntington (please see ), author of numerous books and magazine articles, was perhaps the first engineer and automotive enthusiast to empirically determine mathematical relationships between a vehicle's performance in a 1/4-mile drag race and a vehicle's power and weight. hp & wgt Calculators for 1/4-Mile ET & MPH vs. Differences during mid-season disappear as both population densities have sufficient leaf area.Īdapted From the University of Nebraska-Lincoln cooperative extension.Stealth 316 - Formulas for 1/4 mile ET & mph vs. The plant population in the irrigated field is higher or lower than average. Recognize that a higher population (density) will have higher ET and a lower population will have lower ET in the early and late season. See Factsheet: Soil Water Storage Capacity and Available Soil Moistureħ. The ‘effective’ field capacity is higher after rainfall or irrigation. For slow draining soils, the water (above field capacity) is actually available to the crop for a longer time than in a faster draining soil. Field observations of soil moisture are consistently higher than estimates from scheduling programs. The scheduling programs may not properly represent drainage in the soils. There are differences in emergence dates on irrigated fields. Obtain a separate ET estimate for each irrigated field by selecting the crop and emergence date for all scheduled fields.Ħ. See Factsheet: Irrigation Scheduling with Tensiometersĥ. Check the root zone for soil moisture and irrigate if conditions warrant. Prior to irrigation, there is a dry root zone in the field. Actual crop ET rates may be lower than the estimated ET. If there is a higher than usual frequency of days with precipitation or irrigation make a check of the actual soil moisture conditions.Ĥ.
Et weather calculator full#
Prior to full canopy, rain or irrigation has made the soil surface wet. Actual crop ET rates may be slightly higher than the estimates. See Factsheet: Agriculture Irrigation Scheduling Calculatorģ. Check the growth stage in the field and choose a crop coefficient that reflects the appropriate crop maturity. The estimate of crop growth stage does not match the actual growth stage for the irrigated field. It is difficult to specify specific growth stage lengths for every hybrid variety. If the irrigated field has an unusual exposure, a fixed percentage adjustment to the data may be required.Ģ. Variations in temperature, humidity, and wind occur over short distances as the topography changes. Watch ET from surrounding weather stations – the closest station is not always the most representative. The weather station site has improper exposure. ET estimates can be higher or lower than ET of the irrigated field. Following is a list of possible problems and remedial actions that can help ensure successful use of the ET information for irrigation scheduling.ġ. This is often due to the data not being properly corrected for a particular field situation. When using ET information from, the data provided may not always match what is actually happening in the field.
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