Masters Theses

Date of Award

5-2002

Degree Type

Thesis

Degree Name

Master of Science

Major

Aviation Systems

Major Professor

Ralph Kimberlin

Abstract

Numerous individuals have perfonned wind tunnel tests and flight tests employing half delta strak:es for perfonnance benefits. For this reason, half delta strakes were designed, fabricated, and mounted on a Piper Navajo; a performance flight test was performed. The results of these tests are compared to the results of identical tests conducted by Mr. Courtney Cumberbatch at the University of Tennessee Space Institute in the year 2000. The test employed six half delta strake prototypes manufactured with advanced composite materials. The six prototypes were tested with a 60 degree strake angle and a 75 degree strake angle. These prototypes were designed to be interference drag reducing devices for the Piper Navajo twin-engine airplane and were flight tested for performance benefits. Both the 60 and 75-degree strakes tested during this study were mounted with an 18% overlap and 2°/4 gap. These design and mounting measurements were replicated from the Cumberbatch study. The 60-degree strakes provided 2.4% reduction in the minimum power required and a 2.00/o reduction in maximum range power required. The 75-degree strakes provided a 5 .0% reduction of the minimum power required and a 3. 75% reduction in maximum range power required. These reductions are much smaller than the reductions reported in the Cumberbatch study. Cumberbatch reported that the 75-degree strakes used in his test reduced the minimum required horsepower by 16.2% and the maximum range power required by I 5 .6%. These large differences may have been caused by the use of different data collection consoles and an error in the flight instruments aboard the aircraft during the Cumberbatch flight tests. The 75-degree strakes provide better drag reduction benefits. Both the 60-degree and 75-degree strakes tested in this study decreased the maximum range speed and required horsepower and the maximum endurance speed and required horsepower of the Navajo. For an average cruise condition of 2200 RPM and 170 Brake Horse Power per engine, the 75-degree strake configuration can provide a 50 mile increase in range and a 20 minute increase in endurance. The data also determined that the strakes did not effect the high speed performance of the Navajo.. All data suggests that this strake design is optimum for increasing the maximum range and endurance performance of the Piper Navajo with only a few knots decrease in airspeed and without effecting the cruise performance.

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