gaarder (09/10/82)
Previous article had error which is corrected in this reprint. Error was in units for Rs (sink rate); corrected to fpm instead of fps. ------------------------------------------------------------------------- ------------------------------------------------------------------------- A neat way to determine where to begin descent is as follows: Beforehand; decide what approach speed(V) and rate of sink(Rs) you like and compute; F=(100*V(mph)) / (6*Rs(fpm)); units are miles/1000ft ------------------------------------------------------------------------- Now suppose you are at 9000ft(MSL) and wish to descend to a pattern altitude of 2000ft(MSL): (1) Divide 9000 & 2000 by 1000=9 & 2 (2) Subtract 9-2=7 (3) Multiply 7*F= Distance required to decrease present altitude to pattern altitude Example: Suppose V=120mph and Rs=500fpm then F=4; A factor good for all still air 120mph,500fpm approaches and for this example 7*F=7*4=28 miles ------------------------------------------------------------------------------ This method can be used for ascending, using rate of climb, instead of sink. If you prefer knots, substitute accordingly for mph and miles. Gene Gaarder -WECO