Longeron

Interior of a Boeing/Stearman PT-17 showing small channel section stringers.

In aircraft and launch vehicle construction, a longeron, or stringer^[1] or stiffener,^[2] is a thin strip of material to which the skin of an aircraft or propellant tank may be fastened.

Aircraft

In aircraft fuselage, stringers are attached to formers (also called frames) and run in the longitudinal direction of the aircraft. They are primarily responsible for transferring the aerodynamic loads acting on the skin onto the frames and formers. In the wings or horizontal stabilizer, longerons run spanwise and attach between the ribs. The primary function here also is to transfer the bending loads acting on the wings onto the ribs and spar.

Sometimes the terms "longeron" and "stringer" are used interchangeably. Historically, though, there is a subtle difference between the two terms. If the longitudinal members in a fuselage are few in number and run all along the fuselage length (usually 4 to 8), then they are called "longerons". The longeron system also requires that the fuselage frames be closely spaced (about every 4 to 6 in or 10 to 15 cm). If the longitudinal members are numerous (usually 50 to 100) and are placed just between two formers/frames, then they are called "stringers". In the stringer system the longitudinal members are smaller and the frames are spaced farther apart (about 15 to 20 in or 38 to 51 cm). Generally, longerons are of larger cross-section when compared to stringers. On large modern aircraft the stringer system is more common because it is more weight-efficient, despite being more complex to construct and analyze. Some aircraft use a combination of both stringers and longerons.^[3]

Longerons often carry larger loads than stringers and also help to transfer skin loads to internal structure. Longerons nearly always attach to frames or ribs. Stringers often are not attached to anything but the skin, where they carry a portion of the fuselage bending moment through axial loading.^[4] It is not uncommon to have a mixture of longerons and stringers in the same major structural component.

Space launch vehicles

Stringers are also used in the construction of some launch vehicle propellant tanks. For example, the Falcon 9 launch vehicle uses stringers in the Kerosene (RP-1) tanks, but not in the Liquid Oxygen tanks, on both the first and second stages.^[1]

References

1 2 "Falcon 9 Launch Vehicle Payload User's Guide, Rev 2" (PDF). 21 October 2015. Retrieved 29 January 2016.
↑ Shevell, Richard Shepherd (1989). Fundamentals of flight. Englewood Cliffs, N.J.: Prentice Hall. p. 375. ISBN 0-13-339060-8.
↑ Bruhn, E.F., page C11.29, "Analysis and Design of Flight Vehicle Structures", 1973
↑ Michael C. Y. Niu (1988). Airframe Structural Design. Conmilit Press LTD. pp. 376.

Aircraft components and systems

Airframe structure	Aft pressure bulkhead Cabane strut Canopy Cruciform tail Dope Empennage Fabric covering Fairing Flying wires Former Fuselage Hardpoint Interplane strut Jury strut Leading edge Lift strut Longeron Nacelle Rib Ring tail Spar Stabilizer Stressed skin Strut T-tail Tailplane Trailing edge Triple tail Twin tail Vertical stabilizer V-tail Y-tail Wing root Wing tip Wingbox

Flight controls	Aileron Airbrake Artificial feel Autopilot Canard Centre stick Deceleron Dive brake Electro-hydraulic actuator Elevator Elevon Flaperon Flight control modes Fly-by-wire Gust lock Rudder Servo tab Side-stick Spoiler Spoileron Stabilator Stick pusher Stick shaker Trim tab Wing warping Yaw damper Yoke

Aerodynamic and high-lift devices	Active Aeroelastic Wing Adaptive compliant wing Blown flap Channel wing Dog-tooth Droop Flap Gouge flap Gurney flap Krueger flap Leading edge cuff LEX Slats Slot Stall strips Strake Variable-sweep wing Vortex generator Vortilon Wing fence Winglet

Avionic and flight instrument systems	ACAS Air data computer Airspeed indicator Altimeter Annunciator panel Attitude indicator Compass Course deviation indicator EFIS EICAS Flight data recorder Flight management system Glass cockpit GPS Heading indicator Horizontal situation indicator INS Pitot-static system Radar altimeter TCAS Transponder Turn and slip indicator Vertical Speed Indicator Yaw string

Propulsion controls, devices and fuel systems	Autothrottle Drop tank FADEC Fuel tank Gascolator Inlet cone Intake ramp NACA cowling Self-sealing fuel tank Splitter plate Throttle Thrust lever Thrust reversal Townend ring Wet wing

Landing and arresting gear	Arrestor hook Autobrake Conventional landing gear Drogue parachute Landing gear Landing gear extender Oleo strut Tricycle landing gear Tundra tire

Escape systems	Ejection seat Escape crew capsule

Other systems	Aircraft lavatory Auxiliary power unit Bleed air system Deicing boot Emergency oxygen system Entertainment system Environmental control system Hydraulic system Ice protection system Landing lights Navigation light Passenger service unit Ram air turbine Weeping wing

This article is issued from Wikipedia - version of the 9/6/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.