Originally posted by Traveler
When I tested the 262 at see level it yielded a Mach of .67 for a true airspeed of 505 mph. That translated to an outside air temp at see level of -24 F. What I should have gotten was a air temp of 58 F.
You are also assuming the .67 and 505mph are distinct and exact. Most likely they are neither, thus you have errors due to rounding. For example:
505.49mph / .665 Mach = Approx 760.1mph speed of sound
505mph / .67 Mach = Approx 753.7mph
504.5mph / .6749 Mach = Approx 747.5mph
Plus you appear to have a small conversion error based on HiTech's table. You posted:
Originally posted by Traveler
1116.89f,/* Alt 0.000000*/ yields 762.5588812800001 mph at an air temp of 58F
1097.53f, /* ALT 5000.000000*/ 749.3408025600001 mph 40 F
1077.81f, /* ALT 10000.000000*/ 735.87693312 mph 23 F
1016.38f, /* ALT 25000.000000*/ 693.93547776 mph -32.5 F
Converting fps directly to mph (perhaps you converted to meters/second then back to miles / hour?) yield the following results:
1116.89 fps * 3600 seconds (1 hr) / 5280 feet (1 mile) = Approx 761.5mph
1097.53 * 3600 / 5280 = Approx 748.3mph
1077.81 * 3600 / 5280 = Approx 734.9mph
1016.38 * 3600 / 5280 = Approx 693.0mph
All about 1 mph less than what you have.
This, of course, assumes the Bill Gates product I am using is error free, which could be a stretch.
At any rate, the combination of small rounding / conversion / etc. errors that creep into formulas like this will often give unexpected results.