Aircraft fairing

"Wheel spat" redirects here. For automotive wheel spats, see fender skirts.

An aircraft fairing is a structure whose primary function is to produce a smooth outline and reduce drag.^[1]

The wing root fairing of an American Aviation AA-1 Yankee

These structures are covers for gaps and spaces between parts of an aircraft to reduce form drag and interference drag, and to improve appearance.^[1][2]

A cockpit fairing or "pod" with a windshield on a P&M GT450 ultralight trike

Spats on a Cessna Skylane 182T

An aircraft wheel fairing, commonly called a wheel pant or spat or, by some manufacturers, a speed fairing

Types

On aircraft, fairings are commonly found on:

Belly fairing

Also called a "ventral fairing", it is located on the underside of the fuselage between the main wings. It can also cover additional cargo storage or fuel tanks.^[3]

Cockpit fairing

Also called a "cockpit pod",^{[citation needed]} it protects the crew on ultralight trikes. Commonly made from fiberglass, it may also incorporate a windshield.^[4]

Elevator and horizontal stabilizer tips

Elevator and stabilizer tips fairings smooth out airflow at the tips.^{[citation needed]}

Fin and rudder tip fairings

Fin and rudder tip fairings reduce drag at low angles of attack, but also reduce the stall angle, so the fairing of control surface tips depends on the application.^[5]

Fillets

Fillets smooth the airflow at the junction between two components like the fuselage and wing.

Fixed landing gear junctions

Landing gear fairings reduce drag at these junctions.^[6]

Flap track fairings

Fairings are needed to enclose the flap operating mechanism when the flap is up. They open up as the flap comes down and may also pivot to allow the necessary sideways movement of the extending mechanism which occurs on swept-wing installations.^[7]

Spinner

To protect and streamline the propeller hub.^[8][9]

Strut-to-wing and strut-to-fuselage junctions

Strut end fairings reduce drag at these junctions.^{[citation needed]}

Tail cones

Tail cones streamline the rear extremity of a fuselage by eliminating any base area which is the source of base drag.

Wing root

Wing roots are often faired to reduce interference drag between the wing and the fuselage. On top and below the wing it consists of small rounded edge to reduce the surface and such friction drag. At the leading and trailing edge it consists of much larger taper and smooths out the pressure differences: High pressure at the leading and trailing edge, low pressure on top of the wing and around the fuselage.^[10]

 

The flap track fairings on a Boeing 747

Wing tips

Wing tips are often formed as complex shapes to reduce vortex generation and so also drag, especially at low speed.^[11]

Wheels on fixed gear aircraft

Wheel fairings are often called "wheel pants", "speed fairings" in North America or "wheel spats" or "trousers", in the United Kingdom, the latter enclosing both the wheel and landing gear leg. These fairings are a trade-off in advantages, as they increase the frontal and surface area, but also provide a smooth surface, a faired nose and tail for laminar flow, in an attempt to reduce the turbulence created by the round wheel and its associated gear legs and brakes. They also have the important function of preventing mud and stones from being thrown upwards against the wings or fuselage, or into the propeller on a pusher craft.^[2][12][13]

See also

• Bicycle fairing
• Motorcycle fairing
• Payload fairing

References

1. Crane, Dale: Dictionary of Aeronautical Terms, Third Edition, page 206. Aviation Supplies & Academics Inc, Newcastle Washington, 1997. ISBN 1-56027-287-2
2. Bingelis, Tony: The Sportplane Builder, pages 261-265. Experimental Aircraft Association Aviation Foundation, 1979. ISBN 0-940000-30-X
3. Hitchens, Frank (2015). "Belly fairing". The Encyclopedia of Aerodynamics. Andrews UK. ISBN 978-1-78-538324-3.
4. Cliche, Andre: Ultralight Aircraft Shopper's Guide 8th Edition, page C-17. Cybair Limited Publishing, 2001. ISBN 0-9680628-1-4
5. Molland, Anthony F. and Turnock, Stephen R.:"Marine Rudders and Control Surfaces: Principles, Data, Design and Applications" 1st Edition, section 5.3.2.11. Butterworth-Heineman, 2007. ISBN 978-0-75-066944-3
6. Biermann, David; Herrnstein, William (June 21, 1934). "The Drag of Airplane Wheels, Wheel Fairings and Landing Gear I1 Nonretractable and Partially Retractable Landing Gear" (PDF). Langley Memorial Aeronautical Laboratory: 2–8. (PDF) from the original on April 29, 2017. Retrieved Oct 9, 2018.
7. https://www.freepatentsonline.com/y2016/0340023.html, section 0003
8. Bingelis, Tony: Bingelis on Engines, pages 196-210. Experimental Aircraft Association Aviation Foundation, 1995. ISBN 0-940000-54-7
9. Bingelis, Tony: Firewall Forward, pages 269-273. Experimental Aircraft Association Aviation Foundation, 1992. ISBN 0-940000-93-8
10. Devenport, W.J.; Agarwal, N.K. (December 1990). "Effects of a fillet on the flow past a wing body junction". AIAA. 28 (12): 94–116. Bibcode:1990AIAAJ..28.2017D. doi:10.2514/3.10517. Retrieved October 9, 2018.
11. Met-Co-Aire (2011). . Archived from the original on 16 January 2012. Retrieved 20 January 2012.
12. Bingelis, Tony: Sportplane Construction Techniques, pages 125-130. Experimental Aircraft Association Aviation Foundation, 1986. ISBN 0-940000-92-X
13. Crane, Dale: Dictionary of Aeronautical Terms, third edition, page 377. Aviation Supplies & Academics, 1997. ISBN 1-56027-287-2