AERODYNAMIC CONTRAIL PREDICTION AND CONTROL

THE EXHAUST GASES LEAVING AN AIRCRAFT THAT IS FLYING AT ALTITUDES IN THE HIGH TROPOSPHERE AND LOWER STRATOSPHERE (30,000 TO 60,000 FT) ARE SUBJECT TO COLD TEMPERATURES AS THEY MIX WITH THE AMBIENT AIR. AERODYNE RESEARCH, INC. (ARI) HAS RE- CENTLY MADE SIGNIF ICANT CONTRIBUTIONS IN TACKLING PHYSICAL AND TECHNICAL PROBLEMS RELATED TO CONTRAIL F ORMATION. UNDER NASA SPONSORSHIP, ARI HAS BEEN STUDYING THE DETAILED MIXING DYNAMICS, CHEMISTRY, AND CONDENSATION OCCURING BEHIND AIRCRAFT TO ASSESS THEIR IMPORTANCE IN UPPER ATMOSPHERIC POLLUTION. IN ADDITION, ARI HAS BEEN STUDYING AEROSOLS AND CONDENSATION PHYSICS. THIS COMBINATION OF EXPERTISE AND BACKGROUND GIVE ARI A UNIQUE PERSPECTIVE ON THE PROBLEM OF CONTRAIL PREDICTION AND AVOIDANCE AND ALSO PROVIDE A STRONG FOUNDATION FOR DEVELOPING STRATEGIES FOR EFFECTIVE CONTRAIL CONTROL. PREDICTING CONTRAIL FORMATION ALLOWS FLIGHT PLANS TO BE MODIFIED IF AND WHEN TEMPERATURES AND HUMIDITY CAN BE ASCERTAINED TO BE LIKELY TO PRODUCE CONDENSATION AND, IN A SIMILAR FASHION, AN AIRCRAFT IN FLIGHT COULD BE WARNED WHEN IT WOULD BE EXPECTED TO PRODUCE A CONTRAIL. ACTIVE CONTROL OF CONTRAIL FORMATION WOULD REQUIRE SUCH A WARNING, BUT WOULD THEN REQUIRE THE MODIFICATION OF THE MIXING DYNAMICS AND/OR CONDENSATION KINETICS BEHIND THE AIRCRAFT SUCH THAT WATER AERSOLS WOULD NOT FORM IN THE WAKE BEHIND THE VEHICLE IN THEIR USUAL FASHION. EFFECTIVE CONTROL OFCONTRAIL FORMATION REQUIRES A DETAILED UNDERSTANDING OF THE PHYSICAL AND CHEMICAL EVOLUTION OF THE EXHAUST WATER VAPOR AND CONDENSATION NUCLEI AS THEY ARE PROCESSED IN THE AIRCRAFT WAKE. THIS UNDERSTANDING IS ESSENTIAL FOR PREDICTING WHEN CONTRAILS FORM AND WHEN AND HOW TO MODIFY THEIR FORMATION MECHANISMS. A SUPPRESSION TECHNIQUE BASED ON AN ARI PROPRIETARY CONCEPT, COMBINED WITH THE AERODYNAMIC UNDERSTANDING GROWING OUT OF APPLYING THE ARI VORTEX WAKE MODEL, WOULD FORM THE BASIS FOR A METHOD TO SUPPRESS THE UNDESIRABLE ASPECTS OF NATURALLY OCCURRING AIRCRAFT CONTRAILS. ANTICIPATED BENEFITS/POTENTIAL APPLICATIONS - THE SIGNIFICANT AND LARGE SCALE CONTRIBUTIONS THAT CONTRAILS MAKE TO AIRCRAFT SIGNATURES MAKE THEIR SUPPRESSION VERY IMPORTANT IN REDUCING AIRCRAFT OBSERVABILITY. MODERATE TO LARGE REDUCTIONS IN THE OBSERVABILITY,