Total energy errors due to air-data sampling

Abstract

We have examined the alternative sources of air data available for T.E. compensation. Using published aerodynamic test data, the following conclusions can be drawn: 1. Fuselage statics range from poor to terrible for T.E. compensation. Tuning corrections are generally needed but are not always adequate. Phase errors between pitot and static circuits must be eliminated. 2. A static probe should give acceptable T.E. compensation. Errors are much smaller than fuselage statics. Errors are proportional to velocity so tuning should work well. Phase errors must still be eliminated. 3. It appears from available data that a Nicks probe should give acceptable T.E. compensation. The required manufacturing accuracy is reasonable. There is no possibility of phase errors. A less expensive variometer is required. A gust filter should be used with any venturi probe. If tuning is required it is more difficult than with the pitot/static compensators. 4. Final glide calculators require good pitot and static pressure measurements. A venturi is not sufficient so you have to solve the static problem. A dedicated static probe is probably the most practical solution.