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Larry, Actually, the exact amount could probably be computed with the right table. What’s the ram-air-pressure of 108 mph? It’s measured by every air speed indicator. Source: http://www.ssec.honeywell.com/pressure/datasheets/AN104.pdf Impact Pressure qc In Inches of Mercury for Values of Calibrated Airspeed Vc in Miles Per Hour Calibrated Airspeed, Vc, mph 0 1 2 3 4 5 6 7 8 9 100 .363029 .370347 .377736 .385239 .392785 .400406 .408111 .415888 .423736 .451639 110 .439637 .447433 .455874 .464097 .472391 .480772 .489213 .497731 .506328 .515008 120 .525742 .532566 .541464 .550443 .559480 .568606 .577797 .587070 .596414 .605837 It looks like 100 mph gives .363029 inches of mercury and 110 gives .439637 inches of mercury. Now, we get from http://www.wiredwales.com/info/c_factor/pressure.htm Inches of mercury Pounds/sq. in. 0.4912 one inch of mercury = .4912 psi 100 mph --> .363029 inches of mercury times .4912 psi/inch of mercury = .178312 psi. A little less than two tenths of a pound per square inch. 110 mph --> .439637 * .178312 = .216 psi.
