1,936 research outputs found
Aeroacoustics of lift + cruise eVTOL configurations during transition
No full textDuring the transition of a lift + cruise aircraft from hover to forward flight, the thrust generated by the vertical lifting propellers compensates for the deficit in wing lift at low forward velocities. Predicting the noise generated during this transition phase remains one of the key challenges in the aeroacoustic analysis of these configurations. This study aims to characterize part of the aeroacoustic performance of a lift + cruise aircraft during transition. Anechoic wind tunnel testing was conducted on a wing with vertical lift propellers arranged in a lift + cruise layout, simulating the transition from hover to forward flight. Replicating realistic transition behaviour in an open-jet wind tunnel proved challenging, likely due to jet deflection effects altering the effective angle of attack on the wing. However, by maintaining zero net pitching moment and zero excess vertical thrust across increasing freestream velocities, the study investigated the acoustic contributions of the fore and aft vertical lifting propellers. Results indicate that the rear propeller increasingly dominates the acoustic signature at higher flow velocities, with a corresponding rise in broadband noise. The study further concludes that while rear propeller overlap with the wing benefits aerodynamic performance, it is detrimental to acoustic characteristics
Aerodynamic performance of aircraft wings with stationary vertical lift propellers
No full textImprovements in battery and motor technology are facilitating innovative aircraft configurations capable of vertical take-off and landing. Of these configurations, lift+cruise is popular for its inherent redundancy and the option to tailor separate propulsion systems for each flight regime. During cruise, the vertical flight propellers of a lift+cruise design are inactive and often exposed. Increasing the projected area of a body is understood to increase the drag, but the aerodynamic performance of an edgewise, stationary propeller and its influence on neighboring bodies is less clear. This study aimed to quantify the impact of two, tandem, edgewise and stationary propellers on the aerodynamic performance of a wing using wind tunnel measurements. The stationary position of the front and rear propellers were varied in 30
∘ increments between 0-150
∘, at angles of attack between -4
∘ and 10
∘. Results at Re = 4.3×10
5 showed the propellers and supporting systems had negligible influence on the lift. However, a drag increase of up to 30% was recorded when propeller positions were aligned perpendicular to the wing chord instead of parallel. Variations in the stationary position of the propeller altered the lift to drag ratio by up to 36% in a typical cruise configuration.
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Effect of motor-rotor Geometry on the Performance of Electric VTOL UAVs
No full textThis paper aims to quantify the impact of the orientation and position of a vertical lifting motor-rotor system on the aerodynamic performance of a wing. The analysis was conducted on the scaled wing of an electric uncrewed aerial vehicle using wind tunnel measurements to quantify the difference in performance between configurations. The wind tunnel model was produced by applying a set of non-dimensional parameters to scale an existing quad-plane design, conserving important features to make the result both feasible and generalised. The design was analysed at a Reynolds number of 430,000 to be comparable to the operating conditions of the existing vehicle. The analysis is conducted using two-bladed rotors that are prevented from rotating in the oncoming flow (braked). The influence of the braked angle of the front and rear rotors on the aerodynamic performance of the wing was tested at 30◦ brake angle increments between 0-150◦ over wing angles of attack between -4◦ and 10◦. Results show that the braked angles of the front and rear rotor have a significant impact on the aerodynamic drag. In particular, aligning both rotors so that the blades are perpendicular to the wing chord can result in a 25-30% increase in drag when compared to the case of both rotors aligned parallel to the chord direction. Additionally, the aerodynamic penalty incurred by the vertical lifting subsystem (motors and supporting structure) was also measured
Recording of interview with Bob Buford
No full textBuford lives in Dallas, TX and is a cable-TV pioneer, social entrepreneur, author, and venture philanthropist. He co-founded Leadership Network in 1984, became founding chairman in 1988 of what was initially called The Peter F. Drucker Foundation for Nonprofit Management, and popularized the concept of Halftime through several books he authored. Buford was introduced to Nouwen through Malcolm Street of Elderly Care Inc (Fortworth, TX).1 audio cassette (ca. 1 hr. 9 mins.)The interview is transcribed and is available electronically or in hard copy. ; Title based on contents of the item. ; Reference copies of the audio cassettes are available (located with original). ; Located in audio cassettes box 10. ; Digitized January 27, 2011.For more information please contact Special Collections, the University of St. Michael's College.Item consists of one audio cassette (SR2005 09 23 12) of an interview with Bob Buford conducted by Joe Vorsterman at the Leadership Network Offices (Dallas, TX) on November 30, 2004. Buford recounts experiences with Nouwen at the Foundation Conference (Toronto, ON) and The Gathering (Mexico) and through his subsequent work 'Mornings with Henri Nouwen'. Themes present in Buford's interview include 'Half Time', 'Finishing Well', Thomas Merton, Peter Drucker, Nouwen's contradictions and Nouwen as tortured
Letter from Bob H. Suzuki, President, CSU Pomona, June 13, 1993
No full textA letter from President Bob H. Suzuki thanking guests of a garden reception and asking for their support to fund Michi Nishiura and Walter Weglyn Endowed Chair in Multicultural Studies.These materials are from box 73 and 74 of the Frank Chin Papers. The Frank Chin Papers contain personal and professional correspondence between Frank Chin and Michi Weglyn relating to particular projects on which either author was working as well as files related to the Day of Remembrance Tribute to Michi Weglyn
Relational Enrichment: Bob Lepine
No full textBob Lepine, Little Rock, AR, radio host and author, speaks to the student body on the subject of love and 1 Corinthians 13 as it relates to relationships with others
Bob Miller's Light Walk
No full textArtist Bob Miller's "Light Walk" at the Exploratorium is always an eye-opening experience for students and teachers alike. His unique discoveries will change the way you look at light, shadow, and images. The author includes activities such as doing your own lightwalk, building a pinhole viewer, building a pinhole camera, and slide projector activities. The author also provides an additional bibliography that is accompanied by reading materials. External links to related internet resources are also provided
Jere Nash Interview with Bob Montgomery
No full textInterview conducted by author Jere Nash with state senator Bob Montgomery in the process of writing Mississippi Politics: The Struggle for Power, 1976-2006. Topics covered include Mississippi Senate; Medicaid bill; Brad Dye; Mississippi Highway program and legislation; gambling legislation; tobacco litigation; tort reform; and Montgomery\u27s reelection campaign following reapportionment
Bob Browne, former CEO of the Great Plains Coca Cola Bottling Company
No full textBob Browne is the former CEO of the Great Plains Coca Cola Bottling Company and soon to be author of a new book, The Sys-Tao Way, that outlines his application of the Deming Philosophy.
Bob gives a brief history of the Great Plains Coca Cola Bottling Company, his introduction to the Deming Philosophy and experiences incorporating many of the teachings into his organization. Bob states how the Four Pillars are the key to understanding Deming with a special focus on the theory of knowledge and working relationships.
He describes the difficulty of letting go of his own established paradigms while incorporating the the teachings of W. Edwards Deming - it required constancy of purpose and faith that this was a better way. Bob also shares thoughts on where a CEO or change agent starts and he discusses organizational change and adoption of these ideashttps://digitalcommons.butler.edu/deming_podcast/1006/thumbnail.jp
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