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A Performance Analysis of Folding Conformal Propeller Blade DesignsNASA’s X-57 Maxwell flight demonstrator has a high-lift system that includes 12 fixed- pitch high-lift propellers located upstream of the wing leading edge for lift augmentation at low speeds. These high-lift propellers are only required at low speeds, and to reduce drag, the propeller blades are folded conformally along the nacelles at other operating conditions. The method of designing the high-lift blades permits several variations of blade cross-section placement along the nacelle surface and a comparative performance analysis was needed to determine if any particular design showed significant benefits. We analyzed the performance of three conformal high-lift propeller designs and compared them to that of a non-conformal baseline propeller to establish both the benefit of stowable blades and the value of each variation. In this study, we first performed a drag analysis of each design in the stowed configuration at the X-57 cruise speed and altitude to determine the drag benefits of each conforming method. Then, among blade designs we compared the thrust, power, and lift for a given input shaft speed to establish any performance losses from the baseline. This analysis shows that the conformal blade designs do not have any appreciable performance losses compared to the baseline blades. Moreover, although the drag in the cruise condition is significantly less than for the non-folding baseline, the drag benefits of each conforming blade approach are similar and the value of each approach largely depends on the ease of integration into the nacelle. This paper presents the results of these studies and discusses the benefits and drawbacks of implementing the conformal blade designs. Specifically, we demonstrate that folding, conformal propeller blades contribute significantly less to cruise drag when compared to windmilling, with an increase relative to a. We also show a less than 1% difference in performance formal, folding propellers and the non-conforming baseline propeller.

Document ID
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Litherland, Brandon L.
(NASA Langley Research Center Hampton, VA, United States)
Derlaga, Joseph M.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
April 17, 2020
Publication Date
June 17, 2019
Subject Category
Aircraft Design, Testing And Performance
Report/Patent Number
Meeting Information
Meeting: AIAA Aviation 2019
Location: Dallas, TX
Country: United States
Start Date: June 17, 2019
End Date: June 21, 2019
Sponsors: American Institute of Aeronautics and Astronautics (AIAA)
Funding Number(s)
WBS: 107210.02.06.07
Distribution Limits
Work of the US Gov. Public Use Permitted.
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