Vortilon
Vortilonsare fixedaerodynamicdevices on aircraft wings used to improve handling at low speeds.[1][2]
The vortilon was invented[3]by aerodynamicists working atDouglas Aircraftwho had previously developed the engine pylons for theDouglas DC-8.The original pylons which wrapped around the leading edge of the wing had to be cut back to reduce excessive cruise drag.[4]Wind tunnel testing of the next Douglas commercial aircraft, theDouglas DC-9which had no under-wing engines, showed a cutback engine pylon would be beneficial to wing lift and upwash at the tail at the low speed stall. The pylon was reduced in size and became the vortilon (VORTex-generating-pYLON).[5]
Vortilons consist of one or more flat plates attached to the underside of thewingnear its leading edge, aligned with the flight direction.[6]When the speed is reduced and the aircraft approachesstall,the local flow at the leading edge is diverted outwards; this spanwise component of velocity around the vortilon creates avortexstreamed around the top surface, which energises theboundary layer.[6]A more turbulent boundary layer, in turn, delays the local flow separation.
Vortilons are often used to improve low-speedaileronperformance,[1][7]thereby increasing resistance tospin.They can be used as an alternative towing fences,which also restrict airflow along the span of the wing.[1]Vortilons only stream vortices at highangles of attack[8]and produce less drag at higher speeds than wing fences.[9]Pylons used to mountjet enginesunder the wing produce a similar effect.[10]
The occurrence of span-wise flow at high angles of attack, such as observed onswept wings,is an essential requirement for vortilons to become effective. According toBurt Rutan,vortilons installed on straight wings would not have any effect.[11]
Vortilons were first introduced with theMcDonnell Douglas DC-9to achieve a strong nose down pitching moment just beyond the normal stall and their influence ceased to have any effect beyond 30 degrees angle of attack.[10][12]They have been used on subsequent aircraft, including:
- McDonnell Douglas MD-80
- McDonnell Douglas MD-90
- Boeing 717
- Rutan VariEze,replacingleading edge cuffs(1984)
- Rutan Long-EZ
- Cozy MK IV
- BAe 1251000 series[9]
- Hawker 800XP[7]
- Embraer ERJ 145 family[1]
- Learjet 45[13]
- Aériane Swift[13]
- ExperimentalVought F-8 Crusaderwith supercritical wing. The supercritical wing would have been prone to pitch-up as the wing had increased sweep and aspect ratio compared to the standard wing. No pitch-up problems were experienced with vortilons fitted.[14][15]
- Bombardier Challenger 300,later becoming the Challenger 350 & new 3500 series.
See also
[edit]References
[edit]- ^abcd"Unicom".Flying:75. July 2002.Retrieved2011-10-07.
- ^Houghton, Edward Lewis; Carpenter, Peter William (2003).Aerodynamics for engineering students(5th ed.). Oxford: Butterworth-Heinemann. pp.514.ISBN0750651113.OCLC50441321.
- ^"Stall control device for swept wings".
- ^https:// scribd /document/50976964/Applied-aerodynamics-at-the-Douglas-Aircraft-Company,Fig.23
- ^https://arc.aiaa.org/doi/abs/10.2514/3.43770,p.Fig 13
- ^abRaymer, Daniel P. (1999). "8.2 Aerodynamic Considerations in Configuration Layout".Aircraft Design: A Conceptual Approach(3rd ed.). Reston, Virginia: American Institute of Aeronautics and Astronautics. p.183.ISBN1-56347-281-3.
- ^abMcClellan, J. Mac (November 2002)."Hawker 800XP".Flying:75.Retrieved2011-10-07.
- ^Barnard, R.H.; Philpott, D.R. (2010). "Boundary layer and stalling problems on swept wings".Aircraft Flight(4th ed.). Harlow, England: Prentice Hall. p.75.ISBN978-0-273-73098-9.
- ^abMcClellan, J. Mac (February 1993)."BAE 1000 Lifts Hawker Name to New Heights".Flying:88.Retrieved2011-10-07.
- ^ab"The DC-9 and the Deep Stall".Flight International:442. 25 March 1965.Retrieved2011-10-07.
- ^Vortilons for Variezes,The canard pusher,n°42, October 1984
- ^Shevell, Richard S.; Schaufele, Roger D. (November–December 1966). "Aerodynamic Design Features of the DC-9".Journal of Aircraft.3(6): 515–523.doi:10.2514/3.43770.
- ^abSmith, Steve."Resources for learning about vortilons".NASA Quest. Archived fromthe originalon 2010-11-11.Retrieved2011-10-07.
- ^https://archive.org/details/DTIC_ADA2477198-4
- ^https:// nasa.gov/centers/dryden/pdf/88410main_H-1957V1.pdf,p.87[dead link]
External links
[edit]
Media related toVortilonat Wikimedia Commons- Wing Vortex Devicesfrom Aerospaceweb.org explains vortilons and other vortex-generating wing appliances
