Landing gear noise attenuation

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(12 ) (1o) Patent

United States Patent No.: US 7,954,757 B2

(45) Date of Patent: Jun.

Moe et al. 7, 2011

(54) LANDING GEAR NOISE ATTENUATION (56) References Cited (75) Inventors: Jeffrey W. Moe, Chula Vista, CA (US); U.S. PATENT DOCUMENTS Julia Whitmire, Chula Vista, CA (US); 202,634 A 4/1878 Connor Hwa-Wan Kwan, Chula Vista, CA (US); 1,446,531 A 2/1923 Williams, Jr.

Amal Abeysinghe, Bonita, CA (US) 2,129,824 A 9/1938 De Seversky 2,176,461 A 10/1939 Larsen 2,180,462 A 11/1939 De Seversky (73) Assignee: Goodrich Corporation, Charlotte, NC 2,363,126 A 11/1944 Gibson (US) (Continued) (*) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 FOREIGN PATENT DOCUMENTS U.S.C. 154(b) by 955 days.

CA 2223543 6/1998 (Continued) (21) Appl. No.: 10/599,495 (22) PCT Filed: Mar. 25, 2005 OTHER PUBLICATIONS Ahuja K.K., Martin, J., Miller B., & Gu X., "On Automobile Antenne (86) PCT No.: PCT/US2005/010082 and Roof Rack Noise Control," AIAA 93-4398, 15th AIAA § 371 (c)(1), Aeroacoustics Conference, Long Beach, CA, Oct. 25-27, 1993.

(2), (4) Date: Aug. 20, 2007 (Continued) (87) PCT Pub. No.: W02005/096721 Primary Examiner J. Woodrow Eldred PCT Pub. Date: Oct. 20, 2005 (74) Attorney, Agent, or Firm Womble Carlyle (65) Prior Publication Data Sandridge & Rice, PLLC US 2008/0142634 Al Jun. 19, 2008 (57) ABSTRACT Related U.S. Application Data A landing gear noise attenuator mitigates noise generated by airframe deployable landing gear. The noise attenuator can (60) Provisional application No. 60/557,236, filed on Mar.

have a first position when the landing gear is in its deployed or 29, 2004, provisional application No. 60/641,246, down position, and a second position when the landing gear is filed on Jan. 4, 2005.

in its up or stowed position. The noise attenuator may be an (51) Int. Cl. inflatable fairing that does not compromise limited space B64C25100 (2006.01) constraints associated with landing gear retraction and stow- (52) U.S. Cl . ............ 244/100 A; 244/100 R; 244/102 R; age. A truck fairing mounted under a truck beam can have a 244/102 A compliant edge to allow for non-destructive impingement of (58) Field of Classification Search .............. 244/100 A, a deflected fire during certain conditions.

244/100 R, 102 R 32 Claims, 33 Drawing Sheets See application file for complete search history.

US 7,954,757 B2

Page 2 Fink, Martin R. & Bailey, D.A., Model Test of Airframe Noise U.S. PATENT DOCUMENTS Reduction Concepts, AIAA 6th Aeroacoustics Conf, Jun. 4-6, 1980, 2,406,710 A 8/1946 Riggles, Jr.

Hartford, CT.

2,652,214 A 9/1953 Cussons Hardin, Jay C., Toward a Comprehensive Analysis of Landing 2,719,016 A 9/1955 Wicks Approach Noise Sources, AIAA-97-1593-CP, 1997.

2,747,817 A 5/1956 Saulnier Hayes, Julie A.; Horne, W. Clifton; Soderman, Paul T. & Bent, Paul 4,027,836 A 6/1977 Seibel H., Airframe noise characteristics of a 4.7% scale DC-10 model, 5,058,827 A 10/1991 Dansereau et al.

AIAA-97-1594-CP.

5,104,063 A 4/1992 Harley Heidelberg, L.J., Hall, D.G., Bridges, J.E., & Nallasamy, M., A 5,156,353 A 10/1992 Gliebeetal.

Unique Ducted Fan Test Bed for Active Noise Control and 5,209,434 A 5/1993 Lo Presti et al.

Aeroacoustics Research, CEAS/AIAA-96-1740, May 1996.

5,269,481 A 12/1993 Derrien Heller, Hanno H. & Dobrzynski, Werner M., Sound Radiation From 5,478,030 A 12/1995 Derrien et al.

Aircraft Wheel-Well/Landing-Gear Configurations, Journal of Air- 5,749,546 A 5/1998 Blackner et al.

craft, vol. 14, No. 8, 1977.

6,032,090 A 2/2000 von Bose Heller, Hanno H. & Dobrzynski, W.M., Unsteady Pressure Charac- 6,048,477 A 4/2000 Thorpe et al.

teristics on Aircraft Components and Far-field Radiated Airframe 6,173,920 B1 1/2001 Meneghetti 6,454,219 B1 9/2002 Moe Noise, Journal of Aircraft, vol. 15, #12, Dec. 1978.

6,457,680 B1 10/2002 Dobrzynski et al. Jaeger, S.M., 777 Landing Gear Acoustics: Even More Preliminary 6,619,587 B1 9/2003 Chow et al. Acoustic Results, NASA AST-QAT 4th Airframe Noise.

6,786,451 B2 * 9/2004 Courtois et al. ........ Konstadinopoulos, P., Mook, D.T., & Nayfeh, A.H. (1981), A .. 244/102 R 2003/0102406 Al 6/2003 Chow et al. Numerical Method for General Unsteady Aerodynamics, AIAA 2003/0152145 Al 8/2003 Kawakita Atmospheric Flight Mechanics Conf, 1981.

2003/0164423 Al 9/2003 Courois et al. Konstadinopoulos, P., Thrasher, D.F., D.T. Mook, Nayfeh, A.H., & 2003/0225492 Al 12/2003 Cope et al.

Watson, L.(1985), A Vortex-Lattice Method for General, Unsteady 2004/0040797 Al 3/2004 Plude et al.

Aerodynamics, Journal ofAircraft, 22(1),43-49.

2004/0104301 Al 6/2004 Wickerhoff et al.

Larssen J.V. & Devenport W.J., Acoustic Properties of the Virginia Tech Stability Wind Tunnel, Dept of Aerospace & Ocean Eng, VA FOREIGN PATENT DOCUMENTS Tech, RptVPI-AOE 263,1999.

DE 69715787 2/2003 Macaraeg M.G., Fundamental Investigation of Airframe Noise, EP 846540 6/1998 NASA Langley Research Center Report, 1998.

EP 1067045 10/2001 Miller, Wendell R.; Meecham, William C. &Ahtye, Warren F., Large EP 1192077 8/2004 Scale Model Measurements of Airframe Noise Using Cross-Corre- EP 1340676 6/2005 lation Techniques, J.Acoust. Soc. Am. 71(3), Mar. 1982.

ES 2179282 6/1998 Munson A.G., A Modeling Approach to Nonpropulsive Noise, AIAA FR 2836667 7/2004 76-525, 1976.

GB 494542 10/1938 Piet, Jean-Francois & Elias Georges, Airframe Noise Source Local- GB 534522 3/1941 ization Using a Microphone Array, AIAA-97-1643-CP.

GB 745965 3/1956 GB 9915977 9/1999 Preidikman, S. Numerical Simulations of Interactions Among Aero- GB 2319981 8/2001 dynamics, Structural Dynamics, and Control Systems, PhD thesis, JP 2003/504267 2/2003 VA Polytechnic Inst. & State Unv., 1998.

WO WO01/04003 1/2001 Rao,W.M., Feng,J., Burdisso, R.A., Wg,W.F., Experimental Demon- stration of Active Flow Control to Reduce Unsteady Stator-Rotor Invention, AIAA J., vol. 39, #3, Mar. 2001, pp. 458-464.

OTHER PUBLICATIONS Stoker,R.W. & Sen, R., An Experimental Investigation of Airframe Carter, Guillot, Ng & Copenhaver, "Aerodynamic Performance of a Noise Using a Model-Scale Boeing 777, AIAA-2001-0987, 39th AIAA Aerospace Sciences Mtg & Exh,Jan. 8, 2001, Reno, NV.

High-Turning Compressor Stator with Flow Control," AIAA 37th Stoker, R.W., Recent Airframe Noise Testing Done by Boeing, Pre- Joint Propulsion Conf., 2001, Salt Lake City, Utah.

sented at the NASA AST-QAT 4th Airframe Noise Workshop, Dec.

Davy, R. & Remy, H., "Airframe Noise Characteristics ofa 1/11 Scale 2000.

Airbus Model",4th AIAA/CEAS Aeroacoustics Conf., Jun. 2-4, Stoker, R.W., Underbrink, J.R. & Neubert, F.R., Investigations of 1998, Toulouse, France.

Airframe Noise in Pressurized Wind Tunnerls, AIAA-2001-2107, 7th Dobrzynski W. & Buchholz H., Full-Scale Noise Testing on Airbus AIAA/CEAS Aeroacoustics Conf, May 28, 2001, NL.

Landing Gears in the German Dutch Wind Tunnel, 3rd AIAA/CEAS Wiltshire, W.L., Jr. & Garber, D.P., Advanced Subsonic Transport Aeroacoustics Conf, Paper 97-1597, May 12-14, 1997.

Approach Noise The Relative Contribution of Airframe Noise, Dobrzynski W., Chow L.C., Guion P., &Shiells D., A European Study NASA Tech Memo 104112, Jun. 1992.

on Landing Gear Airframe Noise Sources, 5th AIAA/CEAS International Preliminary Search Report on Patentability Int. Appli- Aeroacoustics Conference & Exh., Jun. 12-14, 2000.

cation No. PCT/US2005/010082 dated Oct. 4, 2006.

Fink M.R., Airframe Noise Prediction Methods, FAAA-RD-77-29, 1977. * cited by examiner

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LANDING GEAR NOISE ATTENUATION ciated with the forward assembly and the fourth lateral edge portion being associated with the aft assembly.

A first compliant edge portion may be affixed to the first RELATED APPLICATIONS lateral edge portion; a second compliant edge portion may be 5 affixed to the second lateral edge portion; a third compliant The present application claims priority to U.S. Provisional edge portion may be affixed to the third lateral edge portion; Patent Application No. 60/557,236, filed Mar. 29, 2004 and and a fourth compliant edge portion may be affixed to the U.S. Provisional Patent Application No. 60/641,246, filed fourth lateral edge portion, such that the first and second Jan. 4, 2005. The contents of these two provisional applica- compliant edge portions are adjacent to one another and the tions are incorporated by reference in their entirety.

io third and fourth compliant edge portions are adjacent to one another.

STATEMENT REGARDING FEDERALLY When the truck fairing is mounted on deployable landing SPONSORED RESEARCH gear of an aircraft, adjacent compliant edge portions are spaced apart from one another by a first distance when the Some aspects of the inventions described in this patent 15 aircraft is on the ground; and move closer to one another when application were made in the performance of work under the aircraft is not on the ground.

NASA Contract No. NAS1-03008 and may be subject to the In another aspect, the invention is directed to a deployable provisions of Section 305 of the National Aeronautics and landing gear truck fairing, comprising: a pair of adjacent Space Act of 1958 (42 U.S.C. 2457).

fairing sections defining a forward assembly and an aft 20 assembly suitable for mounting on a truck, each assembly FIELD OF THE INVENTION having a first side and a second side; a center seal affixed to at least one of the forward and aft assemblies and positioned This invention relates to landing gear noise attenuation and between the two assemblies; adjacent first and second com- more specifically to apparatus intended to mitigate airframe pliant edge portions affixed to the first side of the forward and landing gear noise.

25 aft assemblies; and adjacent third and fourth compliant edge portions affixed to the second side of the forward and aft BACKGROUND assemblies.

When the truck fairing is mounted on deployable landing The interaction of airflow with an airframe's protrusions gear of an aircraft, adjacent compliant edge portions are and cavities creates airframe noise. While engine noise domi- 30 spaced apart from one another by a first distance when the nates aircraft noise at takeoff, the airframe noise created by aircraft is on the ground; and move closer to one another when landing gear is a substantial contributor to approach noise for the aircraft is not on the ground.

many aircraft. During approach, an aircraft engine is operat- Opposing surfaces of adjacent compliant edge portions ing at less power than that during takeoff. Hence, the noise may abut one another when the aircraft is not on the ground.

from the airframe is comparable to that of the engine noise.

35 These opposing surfaces may be are angled.

The landing gear of commercial aircraft represent a com- In yet another aspect, the present invention is directed to a plex system of wheels, axles, trucks or bogie beams, brakes, landing gear noise attenuator for deployable landing gear cable harnesses, torque links, braces, structure interfaces and having a truck beam and tires. The attenuator comprises a tray wheel hubs. Skilled landing gear designers traditionally have positioned under the truck beam; a rigid portion on the tray; emphasized the operational parameters attendant to proper 4o and at least one compliant edge on the tray, the compliant deployment, operation and retraction of landing gear, and edge being proximate to the tires and capable of yielding have not previously been directed to address noise attenuation elastically when a force is applied to the edge.

as a design priority. While various noise reduction designs are In yet another aspect, the present invention is directed to an known for fixed landing gear noise attenuators for deployable inflatable, deployable landing gear noise attenuator adjust- landing gears are less developed.

45 able between a first, deflated position when the deployable There is a need for retractable landing gear attenuation landing gear is retracted, and a second, inflated position when structures that successfully reduce noise emanating from the the deployable landing gear is deployed. The inflatable noise landing gear acoustic signature. The complexity of non- attenuator may take on one of several forms. For example, the acoustical constraints on the design of landing gears have not noise attenuator may be an inflatable door panel fairing suit- permitted effective and practical noise minimization designs.

5o able for attaching to a portion of a door panel. The noise SUMMARY OF THE INVENTION attenuator may be an inflatable main strut fairing suitable for mounting on a main strut of a landing gear assembly. The The present invention is directed to devices and systems for inflatable door panel may be attached to the inflatable main noise attenuation of deployable landing gear. strut fairing. The noise attenuator may be an inflatable truck In one aspect, the invention is directed to deployable land- fairing suitable for mounting on a truck of a landing gear ing gear truck fairing which comprises: an elongated body assembly. The noise attenuator may be an inflatable drag strut connected to a rising front portion, the elongated body having fairing suitable for mounting on a drag strut of a landing gear first and second lateral edges; and first and second compliant assembly. The noise attenuator may be an inflatable torque edges affixed to corresponding first and second lateral edges. link fairing suitable for surrounding a torque link of a landing The elongated body comprises a forward assembly and an 60 gear assembly. A torque link panel may be associated with the aft assembly; the first lateral edge comprises adjacent first and torque link panel. The inflatable torque link may be attached second lateral edge portions on a first side of the fairing, the to the inflatable truck fairing.

first lateral edge portion being associated with the forward In yet another aspect, the present invention is directed to a assembly and the second lateral edge portion being associated system for inflating and deflating inflatable deployable land- with the aft assembly; and the second lateral edge comprises 65 ing gear noise attenuators. Such a system comprises a reser- adjacent third and fourth lateral edge portions on a second voir configured to store pressurized air of sufficient pressure side of the fairing, the third lateral edge portion being asso- to inflate one or more of said noise attenuators, said reservoir

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being connected to a pressure regulator; vacuum means con- FIG. 8E shows a cross-section of either the forward or aft figured to remove air from said noise attenuators; and a mani- assembly of the truck fairing of FIG. 8A.

fold configured to selectively connect said reservoir and said FIG. 8F shows a close-up of one side of FIG. 8E.

vacuum means to said noise attenuators. FIG. 8G shows a cross-section of a compliant edge in A compressor or engine airbleed may be used to charge the accordance with one embodiment of the present invention.

reservoir. The vacuum means may be a dedicated vacuum FIG. 8H shows a cross-section of a compliant edge in pump or a engine vacuum device. accordance with another embodiment of the present inven- In yet another aspect, the present invention is directed to tion.

apparati forpassive noise reduction of landing gear. An exem- FIG. 8I shows a side view of the separation of a compliant plary apparatus is a brake cover fairing partially covering a edge when an aircraft is on the ground.

FIG. 87 piston and piston housing of a front brake of a landing gear shows a side view of a compliant edge when an assembly and having a less than full circumferential design. aircraft is in the air.

Another exemplary apparatus is a fairing insert suitable for FIGS. 9A through 9C are views of a truck fairing of the inserting into a pocket of a brace belonging to a landing gear present invention.

assembly, the fairing insert having a bulbous front section and 15 FIG. 10 is a brake fairing of the present invention.

a tapered rear section to help minimize noise generation. Yet FIG. 11 shows structural fairings of the present invention.

another exemplary apparatus is a pocket filler fairing secured FIGS. 12A and 12B show structural fairings of the present in a pocket of a brace belonging to a landing gear assembly by invention.

means of a non-removable fastener. Yet another exemplary FIGS. 13A and 13B are door/shock strut interface fairings apparatus is a door/strut interface noise reduction fairing 20 of the present invention.

comprising a multi-piece fairing that attaches to a shock strut FIGS. 14A-14D are door/shock strut interface fairings of via an existing hydraulic and/or electrical bracket along a the present invention.

length of said shock strut. Yet another exemplary apparatus is FIG. 15 is a shock strut fairing of the present invention.

a tear-drop shaped shock strut fairing extending from an FIG. 16A is a system diagram of the components for inflat- interface gap around a front of the shock and covering elec- able fairings of the present invention.

trical and hydraulic lines that extend along the front of the FIG. 16B is a pressure reservoir and regulator of the sort shock, the tear-drop shaped fairing being configured to allow used in conjunction with FIG. 16A.

the shock strut to function both in a deployed pre-touchdown FIG. 17 is a front left view showing landing gear fairings of position, and also in compressed position after touchdown. the present invention.

These and other aspects of the present invention will FIG. 18 is an aft view showing landing gear fairings of the become apparent to those skilled in the art after a reading of present invention.

the following description of the preferred embodiments, FIG. 19 is a section view of an inflatable fairing and girt of when considered in conjunction with the drawings. It should the present invention.

be understood that both the foregoing general description and FIG. 20 is a sectional view of an outer girt construction of the following detailed description are exemplary and 35 the present invention.

explanatory only and are not restrictive of the invention as FIG. 21 is an inflatable truck fairing of the present inven- claimed. tion, with wheels removed for clarity.

FIG. 22 is an underside view of a truck fairing of the BRIEF DESCRIPTION OF THE DRAWINGS present invention.

FIG. 23 is an aft view of a truck fairing of the present FIGS. 1 through 3 are views of a conventional prior art invention.

landing gear assembly.

FIG. 24 are drag strut fairings of the present invention.

FIG. 4 is a landing gear containing fairings in accordance FIG. 25 is a sectional view of a drag strut fairing of the with an embodiment of the present invention.

present invention.

FIG. 5A is a partial isometric view of landing gear contain- 45 FIG. 26 is a view of fairings of the present invention.

ing fairings in accordance with an embodiment of the present invention. DETAILED DESCRIPTION FIG. 5B is a partial underside view of a landing gear con- taining fairings in accordance with an embodiment of the Landing gear fairings are an effective approach to reduce present invention. 5o noise. Fairings improve the aerodynamic characteristics of FIGS. 6A through 6D are views of a truck and fairing in the landing gear system, such that the unsteadiness of the accordance with an embodiment of the present invention. airflow is minimized. While fixed fairings have been used FIGS. 7A through 7E are views of a truck fairings of the traditionally for non-retractable landing gear, the employ- present invention. ment of fairings in conjunction with retractable landing gear FIG. 8 is an exploded view of a compliant edge of a truck is limited due to the confined space of the fuselage nose fairing of the present invention. section and of the relatively thin wing sections.

FIG. 8A is a view of another embodiment of a truck fairing Due to size constraints, a full enveloping fixed fairing for a with a compliant edge in accordance with the present inven- landing gear is not feasible. Alternatively, significant noise tion. attenuation is achievable by partially fairing critical compo- FIG. 8B is a view of a close-up of a center seal of truck 6o nents of landing gear.

fairing of FIG. 8A. FIGS. 1, 2 and 3 illustrate a conventional main landing gear FIG. 8C shows the separation between the forward and aft 10. For ease of illustration, certain cable harnesses and assemblies when the aircraft is on the ground, for the truck hydraulic lines are not shown. Landing gear 10, shown in a fairing of FIG. 8A. deployed position, includes wheels 12, axles 14, trucks or FIG. 8D shows the forward and aft assemblies in abutment 65 bogie beams 18, brakes 22, cable harnesses (not shown), via the center seal, when the aircraft is in air, for the truck torque links 30, struts 32, braces 34, structure interfaces 38, fairing of FIG. 8A. wheel hubs 42 and door 46. Unless otherwise stated, the terms

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"down or deployed position" mean when the landing gear is The truck fairing 210 can reflect several design attributes.

deployed, but prior to contact with a runway or other landing This fairing provides foreign object and debris protection to surface. the truck 18. The fairings, suitably designed to withstand such Selected landing gear components are suitable for adapta- impacts, will decrease the overall number of maintenance and tion, modification or redesign featuring aerodynamic compo- 5 repair requirements generated from foreign obj ects impacting nents. FIG. 4 illustrates several types of fixed fairings cover- the gear. The fairing 210 can be designed for ease of main- ing or shielding selected landing gear components. tainability. Preferably, the design minimizes the removal and As shown in FIGS. 4, 5A and 513, a truck fairing 210 can maintenance of the fairing 210, or, alternatively, if removal is cover the forward end, underside, and aft end of the truck needed, the removal and installation procedures are simple beam, respectively. The truck fairing 210 also can extend to io enough to not significantly increase the task time required for cover the brakes 22, and certain wire harness (not shown). In routine maintenance. In another embodiment, drain holes are another embodiment, the truck fairing 210 may extend to incorporated in the fairing to allow removal of any hydraulic cover the torque links 30. FIG. 5A shows an isometric view of fluid or other liquids that may gather in the normal course of the fairing 210 covering the truck beam 18, axles 14, and landing gear operation and servicing. Routine inspections can brakes (partially) 22 on a landing gear. FIG. 5B shows a view 15 be performed to ensure that any foreign objects or debris, from the underside of the landing gear. including rocks, safety wire, etc., has not collected in the The truck fairing 210 may be a rigid structure, or may fairing. If an actively driven smart fairing is installed on the consist of a rigid lower fairing and a smart, or retractable, truck 18, a routine inspection of the hydraulic or electrical upper fairing. To accomplish a smart or retractable upper system used to drive the smart fairing will be necessary.

truck fairing, a localized torque link fairing along with 20 FIGS. 7A-7E, 8, 8A -8H, and 9A-9C show a compliant bundled, shielded or rerouted cable harnesses may be edge and truck fairing. As used herein, "compliant' means employed. Alternatively, a truck fairing, or combination of willing to yield, extend or displace elastically in response to a fairings, that retract or rotate after landing to allow air flow for force, but capable of substantially resuming its original shape brake cooling, access to the tow fitting, and access to the thereafter. The compliant edge in this embodiment is proxi- jacking pad can be employed. The movement of the smart 25 mate to the tires and capable of yielding elastically when a upper fairing can be accomplished by adding a powered force is applied to the edge. The compliant edge is capable of hydraulic or electrical system to drive the fairing. substantially recovering size and shape after deformation.

An alternative approach would be to use the stroking of the The truck fairing can comprise a tray positioned under the gear to static position and kinematics of braces or links to truck beam, a rigid portion on the tray and at least one com- drive the fairing. In other words, as the landing gear goes 30 pliant edge on the tray.

through its deployment stage on approach, the hydraulic and/ More specifically, FIGS. 7A through 7E show views of a or electrical systems that are used to deploy the gear to its truck beam, with a fairing 1210 disposed under the truck final, fully extend position can also be used to operate/deploy beam. The fairing 1210 can be comprised of fairing sections a smart upper truck fairing that addresses the torque link, 1214, 1216, 1218 that cover the underside of the truck, brake forward and rear cable harness noise sources. Implementation 35 rods and brakes, with a fourth section 1220 secured proximate of such methods and techniques are known to those of skill in to the tow fitting to cover the forward truck, tow fitting, the art. jacking pad, and front brakes.

The design of truck fairing 210 can reflect several design A compliant edge 1250 can comprise nylon or other suit- considerations. The fairing accommodates access to the jack- able type of bristles, proximate to the tires 13, brakes 22, ing pads, tow fitting, and brakes 22. The lower portion of the 40 wheel hub 42 and wheels 12. The bristles can be attached fairing 210 blocks a substantial portion of the underside of the through riveting strips 1252 or other suitable connectors.

truck 18, but retains room for tire clearance. The truck fairing Alternatively, the compliant edge 1260 can comprise soft 210 can present a location for the collection of debris, and rubber or other elastomeric polymer. The compliant edge ease of inspection (and removal of such debris) is required. further can be made of a material that is inert, chemically The truck fairing 210 also must be shaped and configured to 45 resistant and/or heat resistant.

allow for retraction and stowing of the gear in selected aircraft In one embodiment, the edge is constructed of a molded associated with the landing gear 10. plastic or thermoplastic polyolefin such as Dexflex® 880 FIGS. 6A, 613, 6C and 6D illustrate layouts of the truck made by D & S Plastics International Partnership of Grand 210.

fairing For certain types of landing gear, installation of Prairie, Tex.

the fairing 210 will require modification of the existing gravel 50 FIG. 7E shows the fairing 1210 with a compliant edge 1250 shields, which can be mounted to the two junction boxes on in a view looking aft. In this view, some of the compliant the underside of trucks. To assemble fairing 210, the design bristles 1252 are in front of the tire, and not deflected, while can comprise one or more separate fairing sections. Four other bristles 1254 are shown as being deflected as a result of fairing sections 214, 216, 218, 220 are shown in FIGS. 6A, the tire contacting the bristles 1254 of the compliant edge 613, 6C and 6D. Three of these fairings 214, 216, 218 55 1250.

can cover the underside of the truck 18, brake rods and brakes, FIG. 8 shows an exploded view looking aft of the fairing with a fourth section 220 secured onto the tow fitting to cover and landing gear where the fairing 1210 has a compliant edge 1260. 1220, 1218, 1216 the forward truck, tow fitting, jacking pad, and front brakes. The rigid portions (such as sections The fairing 210 can be made of any aerospace-grade metal and 1214 shown in FIG. 713) of the fairing 1210 can be made alloy, or of a suitable composite material, sheet metal or 60 of rigid metallic or composite materials, and are mounted plastic. about the truck bogie beam 18 with a support arm 1270, and The truck fairing 210 can be secured to the landing gear 10 arch 1280, as shown in FIG. 8. A bias member 1290, which in various manners. For example, standard fasteners already can be in the form of spring steel or other suitable materials, used on the landing gear truck 18 could be lengthened and can be provided and i s mounted to a rigid portion of the fairing used to restrain the fairings to existing brackets. Alternatively, 65 1210, as shown in FIG. 8. A compliant edge 1260 can then be band clamps 224 or other suitable forms of securing could be connected to the bias member 1290 and fairing 1210. The used to secure the fairing 210 to the truck 18. compliant edge 1260 can be made of rubber, such as Dex-

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flex® 880. In one embodiment, the compliant edge can be the center seal 806 is spaced apart from the flange 808a so that located a distance LE from the gear centerline 1255. In an there is no contact therebetween. On the other hand, when the embodiment suited for the Boeing 777 aircraft, for example, aircraft is in the air, the flanges 808a, 808b of the aft assembly the distance LE can be from about 12 to 17 inches, and 802 and forward assembly 804, respectively, are separated by preferably about 15 inches, and most preferably about 14.9 5 a lesser, second distance D2, which is approximately 0.8-1.0 inches. The rigid portion can have a width of about 24 inches, inches. In this condition, the center seal 806 abuts the flange or preferably about 23.8 inches. 808B of the forward assembly and the center seal 806 is FIG. 8A shows another embodiment of a toboggan-type slightly compressed. It can therefore be seen that there is a truck fairing 800. Fairing 800 includes an elongated body 801 difference in separation between the forward and aft assem- connected to a rising forward portion 802A that preferably is io blies, depending on whether the aircraft is in flight, or on the curved. The elongated body 801 has lateral side edges 811, ground. It is further understood while in the embodiment 813 to which are affixed compliant edges, discussed further described above, the center seal 806 is secured to the flange below. 808a of the aft assembly 804, one may instead secure the The fairing 800 includes a rigid forward panel assembly center seal 806 to flange 808b of the forward assembly 802.

802 that is adjacent to the curved forward portion 802A. The 15 As also shown in FIG. 8a, the fairing 800 is provided with fairing 800 also includes a rigid aft panel assembly 804 which four compliant edge portions 830. A first pair of these, 830a, preferably has the same width as the forward assembly 802. 830b, are provided on the first lateral edge 811 of the elon- Thus, fairing 800 can comprise a plurality of fairing sections. gated body 801, while a second pair 832a, 832b are provided The forward and aft assemblies 802, 804 can be formed of on the second lateral edge 813. Thus, each lateral edge 811, metallic or composite materials. In the case of metallic mate- 20 813 comprises adjacent portions the forward assembly 802 rials, they may be formed of aluminum. In the case of metallic and the aft assembly 804 on one side of the elongated body materials, they may be formed of aluminum. In one embodi- portion 801. Furthermore, each lateral edge 811, 813 is pro- ment, the forward assembly 802 and the aft assembly 804 are vided with a compound compliant edge that comprises a pair unconnected to one another. They are mounted to respective of separate compliant edge portions adjacent to one another.

forward and aft portions of a truck or bogie beam 18 and/or 25 FIGS. 8i and 8j show the compliant edge in the foreground other parts of the landing gear, and are separated by a center and omit the central seal, but otherwise are similar to FIGS. 8c seal 806, described below. The underside of the fairing 800 and 8d. As seen in FIG. 8i, when the aircraft is on the ground, preferably is flat, in contrast to truck fairing 210. the adjacent forward and aft compliant edges 830a, 830b, The front assembly 802 further comprises a forward panel respectively, on the same side of the fairing 800 are spaced support assembly 810A including a mounting bracket 810B 3o apart from one another, due to the increased separation expe- for mounting to the inside surface of the curved forward rienced by the forward and aft assemblies 802, 804, discussed portion 802A. In addition, the front assembly 802 includes a above with respect to FIG. 8c. Preferably, the opposing ends forward upper shield plate 812A having a raised medial sur- of adjacent forward and aft compliant edges are angled at face 814A, and an aft junction box 816A atop a portion of the complementary angles, such as about 45 degrees, so as to raised medial surface 814A. 35 form angled abutments 870a, 870b when in the unloaded The aft assembly 804 includes an aft upper shield plate condition.

812B having a raised medial surface 814B, and an aft junction And as seen in FIG. 8j, when the aircraft 800 is in the air, box 816B atop a portion of the raised medial surface 814B. the forward and aft assemblies 802, 804 are closer to one The far aft end of the aft assembly 804 is provided with a pin another and the adjacent forward and aft compliant edges 820 atop a rearwardly projecting fin 822 belonging to an 4o 830a, 830a on the same side of the fairing 800 to abut one upstanding support 824. another at abutments 870a, 870b. The angled cut at the abut- Also, at spaced intervals along the length of the forward ment interface helps prevent excessive deformations at the and aft junction boxes 816A, 816B, respectively, are shield end due to misalignment when the adjacent compliant edges supports 826 and braces 828. meet.

As seen in FIG. 8A, a center seal 806 extends in a direction 45 As seen in the cross-sectional view of FIGS. 8e and 8f of transverse to the elongated body 801 and along at least a either the front or aft assembly, 802, 804, the fairing 800 portion of the width of the fairing 800 separates the forward comprises lower shield plates 834a, 834b opposing corre- assembly 802 from the aft assembly 804. As seen in FIG. 8B sponding upper shield plates 812a, 812b. Preferably, the where the compliant edges 830a, 830b, 832a, 832b have been upper shieldplates are formed from aluminum having a thick- removed, the center seal 806 preferably is formed from a 5o ness of about 0.1 inches, while the lower shield plates are flexible, compressible elastomeric material. As shown in FIG. formed from aluminum having slightly less thickness, on the 8c, the center seal can comprise a generally rectangular order of about 0.063 inches thick. It is understood that other body portion 806a having a longitudinally extending hollow thicknesses of aluminum, and even other materials, may be aperture 806b, and a downwardly extending tongue portion used.

806a 55 838 806c connected to the top region ofthe body portion and As seen in FIG. 8f, the elongated gripping portion of extending in a direction parallel to a proximate sidewall of the the compliant edge 830 is inserted between the upper shield body portion 806a. plates 812a, 812b and the lower shield plates 834a, 834b and 840.

As seen in FIGS. 8c and 8d, the rear end of forward assem- secured to these by fasteners A weight bearing spacer bly 802 and the front end of the aft assembly 804 can be 836 is positioned inward of the gripping portion 838, between provided with upturned flanges 808a, 808b, respectively. In 60 the upper shield plates 812a, 812b and the lower shield plates one embodiment, the flange 808b is secured to the center seal 834a, 834b. The spacer 836 is located below the support 826 806 at the tongue portion 806c. This is done by adhesive or by and thus serves as a weight-bearing element, thereby prevent- riveting, although other techniques may also be employed. ing the elongated gripping portion 838 of the compliant edge When the aircraft is on the ground (the `loaded' condition), 830 from being crushed between the upper shield plates 812a, the flanges 808A, 808B of the aft assembly 802 and forward 65 812b and the lower shield plates 834a, 834b. Preferably, the assembly 804, respectively, are separated by a first distance spacer 836 has a thickness between about 0.2 to about 0.3 Dl, which is approximately 1.2-1.6 inches. In this condition, inches, and more preferably is 0.25 inches.

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As seen in FIG. 8g, the projecting portion 840 of the com- the aircraft is maneuvering. The most extreme deflections pliant edge has a length D3, which preferably is between occur when an aircraft has a maximum load, such as when an about 2 to about 4 inches and more preferably is about 3 aircraft is fully loaded with fuel, passengers and cargo for inches. The compliant edge's tip portion 842 is angled take-off. Under such loads, the aircraft may have to pivot slightly upwardly, relative to the remainder of the compliant 5 about its main gear, leading to tire deflection. These deflec- edge. The length D4 of the tip portion 842 is preferably tions are increased if the main gear steering is not used. The between about 0.75 and about 1.25 inches in length, and more specific design parameters for the truck fairing and compliant preferably is about 1 inch. Furthermore, the tip portion 842 edge will be dependent upon the landing gear and amount of preferably is angled upwards between about 10° to about 30°, tire deflection anticipated and/or measured. The width of the although amounts outside this range may also be effective. io fairing and associated compliant edge can be maximized, but In one embodiment, as shown in FIG. 8g, the compliant preferably not so wide as to contact the tire or wheels during edge 830 has a two-ply polyester/fiberglass reinforced core normal taxiing, take off, landing or normal ground maneu- 844 in areas away from the gripping portion 838 and a four- vering while the tire may be turning at high speeds. Preferably ply polyester/fiberglass reinforced core 846 in the gripping the compliant edge does not contact the tire under such con- portion 838, especially in those areas proximate to the fasten- 15 ditions in order to avoid tire wear. The extreme maneuvering ers 840. Surrounding the cores 844, 846 is an elastomeric conditions where contact occurs with the tire and compliant material 848 which gives the compliant edge 830 its shape. edge should occur seldom and should not contribute to exces- The elastomeric material 848, in turn, is covered with a knit sive tire wear because of the low incidence of occurrence and cover 850 to provide a smooth surface finish. In one embodi- the low rotational speeds of the tires under such extreme ment, the knit cover 850 is formed of Dacron®. 20 conditions.

Preferably the core 846 comprises a polyester/fiberglass A truck fairing with a compliant edge allows the fairing to reinforced cloth. The stiffness of the compliant edge in a block or limit air flowing through or around the edge while at widthwise direction may be varied by changing the number of the same time being flexible enough to deflect during extreme layers of the polyester/fiberglass reinforced cloth. To prevent ground maneuvering or even tire rupture. The compliant edge excessive wear and/or damage, a 2-ply construction is pre- 25 can be comprised of rubber or fabric stripping, fiber rein- ferred in areas of the compliant edge that are proximate to the forced rubber, nylon brush, spring steel or an inflatable blad- tires while a 4-ply construction is preferred in areas away der, and other equivalent structures. Such compliant edges from the tires to provide enhanced greater stiffness. allow for proper functioning of a noise attenuator, while mini- FIG. 8h shows an alternative embodiment of a compliant mizing any adverse effects of tire rub. Although in the edge 860 in which the tip portion 862 is not angled, the 30 embodiments shown, the compliant edge is provided only in compliant edge 860 being similar in construction to compli- proximity to the tires, the compliant edge can extend the ant edge 830 seen in FIG. 8g. entire edge of the fairing proximate to the tires. Such an Under normal operating conditions, whether on the ground embodiment would allow for forward-aft adjustments, and or in the air, the compliant edges 830, 850 are not intended to possibly provide a universal fit for multiple landing gear be deflected by brushing against the tires and/or wheels, as are 35 configurations.

bristles 1254, discussed above with respect to FIG. 7E. Thus, FIG. 10 illustrates a fixed brake cover fairing 240. Fairing no tire/wheel rub is expected with compliant edges 830, 850. 240 streamlines the airflow over the brakes by partially cov- FIG. 9A through 9C show further views of a fairing 1210, ering the piston and piston housing of the front brakes. The with the compliant edge 1250 installed. In an embodiment less than full circumferential design of the fairing 240 pro- suited for the Boeing 777 aircraft, the fairing 1210 can be 40 motes cooling to minimize the effect of the fairing on brake attached to the main truckbeam 18 with fittings common to an performance and to promote brake cooling while the aircraft electrical box 212, which can house various cabling and wires is parked at the gate.

used in the landing gear. The fairing 1210 replaces a gravel Alternatively, the fairing 240 may also incorporate smart shield (not shown) on the current Boeing 777 design used to fairing components that retract out of the way while the protect the electrical box. In the embodiment shown, the 45 aircraft is onthe ground to facilitate brake cooling. The design clearance between the fairing and the brake disks 22 is about of fairing 240 may also incorporate brake cooling ducts to 0.4 inches. help decrease the time required for brake cooling.

A truck fairing 1210 with a compliant edge 1260 in accor- In addition, or in the alternative, to a separate brake cover dance with this invention allows the fairing 1210 to fit inclose fairing 240, a brake fairing concept can be incorporated into proximity to the landing gear tire 13. Noise tests have dem- 50 the lower truck fairing design 210. As shown in FIGS. 6A and onstrated that noise reduction is a function of the distance 613, the truck fairing 210 partially covers the front brakes on between the fairing and edge of the tire, with fairings that the landing gear. The fourth piece 220 of the truck fairing can minimize the gap between the fairing edge and the tire per- be secured to the tow fitting and cover the front brakes on forming well. This relationship was demonstrated during landing approach.

wind tunnel testing of a landing gear with no fairing, a landing FIGS. 11 through 12 illustrate fairings used to minimize gear with a narrow width truck fairing, and a landing gear noise emanating from cavities and pockets in structural mem- with a maximum width fairing. Under wind tunnel test con- bers. These fairings 260, 264 provide aerodynamic shapes to ditions equivalent to an aircraft landing approach velocity, a the braces 34 of the landing gear to reduce wakes generated flyover angle of incidence and a truck angle of 13 degrees toe by the braces, as well as filling in open ended pins. "Pocket up, the noise levels consistently decreased at numerous fre- 60 filler" fairing inserts 260 can comprise low weight foam quencies as the fairing width increased. material, plastic, composite and/or metal alloy insert. The use While test have demonstrated that a wide truck fairing is of plastic and/or metal (such as aluminum) as opposed to a beneficial, the integrity of a fairing structure may be at risk if foam insert increases weight, but maybe easier to attach to the the fairing is too close to the tires. Aircraft tires can deflect structure and decreases the concern for possible foreign under landing loads and ground maneuvering. Hence, even if 65 object and debris damage.

a clearance between the tires and fairing exists when the Fairings 260 can also comprise acetal resin inserts, such as aircraft is at rest, this clearance can be reduced to zero when Dupont's Delrin® resin, that fit inside the pockets of the side

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and drag braces. These inserts can be restrained to the braces As shown in FIG. 16A, the deployment and retraction of using existing attachment slots in the pockets. The shallow the inflatable fairings preferably is achieved through air pres- pockets on the sides of the braces do not necessarily require sure actuation and retraction. When the landing gear is inserts, only the deeper pockets on the top and bottom of the deployed, a pressure regulator 101 can be triggered to inflate braces. End caps also can be installed in hollow pins 35 about 5 the fairings 510, 520, 530 via a manifold 124, as the landing the gear. Known manufacturing practices can be utilized to gear comes into the air stream. A 400 cubic inch reservoir 114 manufacture the filled braces. can be charged to approximately 2,000 psig with air to inflate As shown in FIG. 12A, fairing 264 can be designed to have the fairings. A compressor 118 can charge the reservoir 114 to a bulbous front section 265, and a tapered rear section 263, to approximately 2,000 psig pressure. A vacuum pump 122 can help minimize noise generation. 10 deflate the fairings once the airplane is on the ground. The The "pocket filler" fairings 260 can be designed to allow fairings can stay deflated during airplane takeoff. The vacuum for ease of installation and removal. As shown by the filled applied to the fairings can keep the fairings from excessive brace pockets of FIG. 12B, installation can be by traditional movement or flapping in the air during takeoff. Alternatively, removable or non-removable fasteners 267. Alternatively, in bleed air 126 from the engine can be used to charge the new construction, the braces can be fabricated without any 15 reservoir and an engine vacuum device 127 can apply a pockets or cavities. When removable fasteners 267 are used, vacuum pressure thereby eliminating the need for a compres- the fasteners 267 allow ease of removal of the fairings for sor and vacuum pump.

inspections for potential cracking and corrosion of the struc- The pressure regulator 101 and reservoir 114 are shown in tural members underlying the fairings, as well as inspections FIG. 16b. In one form of operation, reservoir 114 can inflate for moisture that may collect between the fillers and structural 20 the fairings quickly, preferably within 2 to 5 seconds from the members. time inflation is initiated. The reservoir 114 can be any suit- FIGS. 13 and 14 illustrate door/shock strut interface fair- able size depending upon the volume of the inflatable fairings ings. These fairings reduce noise by eliminating the gap and charged to approximately 2,000 psig pressure. In one between the door 46 and strut 50. In the case of fairing 280, embodiment, the reservoir can have a volume of 400 cubic the gap is eliminated by making modifications to the edges of 25 inches. An air compressor 118 on board the airplane can be the door shape, and inserting a fairing 280 in the gap between used to charge the reservoir 114. The pressure regulator 101 door and the strut. As shown in FIG. 13B, a fairing 284 can be controls the pressure of air flowing into the inflatable fairings attached to the door or shock strut. 510, 520, 530. The pressure regulator 101 actuation can be In another embodiment, as shown in FIGS. 14A-14D, a triggered by the landing gear door opening mechanism. The door/strut interface noise reduction fairing 288 comprises a 30 pressure regulator 101 canbe set at apredetermined setting as multi-piece fairing that attaches to the shock strut via the appropriate for the tubing and dynamics of each installation.

existing hydraulic and electrical brackets along its length. A compressor 118 can charge the reservoir to approxi- The fairing extends from the door around the front of the mately 2,000 psig pressure so that the pressurized air can be shock strut and around the side of the gear, incorporating the used to inflate the noise reduction fairings at the time of shock strut concept. The door to shock strut and systems 35 landing. To keep the weight as low as possible, the compres- fairing can be made of aerospace grade aluminum alloys; sor preferably is a low displacement type, high pressure alternatively, other materials including composite structures device that is capable to charging a reservoir to 2,000 psig may be used. while the airplane is airborne. If bleed air from the engine can FIG. 15 shows a tear drop shock strut fairing 292 that be use to charge the reservoir, the need for the air compressor extends from the interface gap around the front of the shock, 40 will be eliminated.

covering the electrical and hydraulic lines that run along the A vacuum pump 122 can be used to remove air out of the front of the shock strut. Such a fairing can be added as a inflated fairings once the airplane has landed. In most cases, retrofit to an existing strut, or incorporated into a design of a the fairings can stay deflated during airplane takeoff. The new landing gear strut. During operation, the shock strut vacuum applied to the fairings will keep them from moving or fairing 292 is designed to allow the shock strut to function 45 flapping in the air during takeoff. Maintaining the fairings in both in the deployed but pre-touchdown position, and also in their deflated condition during takeoff also will better facili- the post-runway, compressed position. This function is per- tate the articulation and movement of the landing gear struts mitted by the fairing internal construction allowing for suffi- during the gear stowage operation. If a bleed air ejector valve cient clearance for compression of the shock strut when the can be used to provide vacuum, the need for a vacuum pump landing gear contacts the runway or ground surface during 50 can be eliminated. To assure that the fairings do not exceed the landing. The attachment points of the fairing 292 also avoid maximum designed pressure, a pressure relief valve 505 can interference with such shock strut compression. be used for each fairing. Alternatively, if the pressure can be The fairings as described herein can be installed and adequately controlled by the regulator 101, the requirement removed, ideally, by a single individual. Sharp edges on the for the pressure relief valves may be eliminated. High pres- 55 19 fairing should be avoided in order to avoid creating safety sure hoses 104 as depicted in FIGS. and 25 can be used to hazards. Benefits for these fairings may include a reduction in direct high pressure air to the inflatable fairings, as well as to the size and weight of the dressings that these fairing would deflate the fairings when desired.

protect. In addition to aiding noise reduction, the fairings of FIGS. 17 and 18 illustrate several additional embodiments this invention may also act as a foreign object and debris for noise reduction attenuation. The deployed fairings 540, deflector, reducing the need to increase the material size of the 60 580, 600, 620, 630, 640, 650 form an aerodynamic shape dressings that the fairings protect. around various components of the landing gear when the In another embodiment, a deployable fairing can operate to fairings 540, 580, 600, 620, 650 are inflated in an embodiment deploy upon extension of the landing gear, and then retract to approximately 2.5 psig pressure. In the embodiments when the landing gear is stowed within the nose section and shown, a torque link fairing panel 630 and door panel fairing wing sections. A landing gear fairing, for example, can inflate 65 640 are non-inflatable fabric panels that are deployed on, when the landing gear is deployed, and deflate when the around, or between components of the landing gear and the fairing is not required or desired. inflatable fairings 540, 580, 600, 620, 650, which serve as

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deployable landing gear noise attenuators. As will be appar- Inner girt 120 can be made from various pliable materials ent to persons of ordinary skill in the art, other combinations including, for example, a woven nylon fabric coated with polyurethane. Such materials presently are used to construct of inflatable and non-inflatable fairings also may be used. For inflatable evacuation slides for commercial aircraft, for example, door panel fairing 640 may include an inflatable 5 example. Outer girt 130 may be made from a combination of portion that at least partially fills a space between the main typical girt material and a highly durable material, such as strut and door panel on a landing gear, and blocks or deflects Keviar® fiber, to protect the inflatable fairing from debris noise-producing air flows that would otherwise pass between during landing. FIG. 20 shows the construction of one the main strut and door panel. The shape of the inflatable embodiment of the outer girt 130, comprising an outer debris- fairings can vary, depending upon aerodynamic or space con- io resistant layer 136, a girt material layer 138, and the inflation figuration requirements.

tube 134. Preferably, the outer debris-resistant layer 136 and Each inflatable fairing 540, 580, 600, 620, 650 can contain girt material layer 138 are stitched and/or bonded to one one or more inflatable chambers there within. Each inflatable another. The girt material 138 and inflation tube 134 may be chamber may require one pressure relief valve 505. The mate- bonded to one another such as by a suitable adhesive.

rials forming the inflatable fairings can comprise any material 15 Returning to FIG. 17, an inflatable main strut fairing 540 is that is flexible and suitable for pressurization. The exterior of shown in its deployed position. The main strut fairing sub- the fairings should be tear-resistant and capable of withstand- stantially envelopes the main strut of the landing gear, pro- ing the environment encountered by aircraft during takeoff viding an aerodynamic profile to attenuate noise during land- and landings. To minimize damage from debris impact, at ing. The main strut fairing 540 covers an outer cylinder (not least portions of some outer surfaces of the fairings can be 20 shown) of a conventional landing gear. During touchdown, as made from Kevlar® fibers or other suitable durable fibers and the inner cylinder (not shown) of the landing gear moves material. To minimize weight, the use of high strength fibers within the outer cylinder, the main strut fairing 540 can move such as Kevlar® fibers can be limited to debris impact areas relative to other components on the landing gear.

only. The fairings can be secured to the structure using a girt During operation, the main strut inflatable fairing 540 is arrangement as discussed below. 25 designed to allow the shock strut to function both in the As shown in FIGS. 17 and 18, an embodiment of an inflat- deployed but pre-touchdown position, and also in the post- able fairing system may include a main strut fairing 540, a runway, compressed position. This function is permitted by forward drag strut fairing 650, an aft drag strut fairing 600, a the inflatable fairing internal being configured, dimensioned torque link fairing 620, a torque link fairing panel 630, a door and mounted so as to allow sufficient clearance for compres- panel fairing 640, and a truck fairing 580. 30 sion of the shock strut when the landing gear contacts the As shown in FIGS. 17 and 26, an inflated and deployed runway or ground surface during landing. The attachment main strut fairing 540 surrounds a large portion of the main points of the fairing 540 also avoid interference with such strut of the landing gear. shock strut compression.

As shown in FIGS. 17, 18, 22, and 24, an inflated and An inflatable truck fairing 580 also is shown in FIG. 17, as deployed aft strut fairing 600 envelopes all or most of the aft 35 well as in FIGS. 21, 22 and 23. The inflatable truck fairing 580 drag strut of the landing gear. can wrap substantially around a conventional truck structure FIGS. 17, 22, 24, and 25, show an inflated and deployed like that depicted in FIGS. 5A & 5B. The top portion 582 of forward drag strut fairing 650 positioned around the forward the truck fairing 580 can be secured by wrapping inner and drag strut of the landing gear. The inflatable fairings 540, 600, outer girts around the truck. The bottom portion 586 of the 650 provide the main, aft, and forward struts with enhanced 40 truck fairing 580 can be secured by wrapping the inner and aerodynamic profiles. outer girts around an existing rock guard (not shown) under FIG. 19 shows a cross-section of one embodiment of an the truck. To keep the truck fairing 580 within the confines of inflatable fairing 100 according to the invention. In this the wheels of the landing gear, the inflatable fairing near the embodiment, the fairing 100 includes an inner girt 120 and an wheels can have specially shaped inner panels 585 like those outer girt 130. The inner and outer girts 120, 130 are joined 45 depicted in FIG. 23. As described above, an inner girt is used together on either side 106,108 of a separation 105 such as by primarily to secure the inflatable fairing to the truck and an stitching and/or adhesives. The separation 105 in the girts outer girt primarily provides its shape. As shown in FIG. 23, 120, 130 permits the fairing 100 to be wrapped around a the truck fairing 580, when inflated, is configured and dimen- structural member of a landing gear such as a strut. Laces 110 sioned to essentially stay within the boundaries of the wheels may be used to connect edges 106, 108 and to tighten and 50 without touching them.

securely retain the inner girt 120 on the enveloped structural FIGS. 24, 25 and 26 illustrate the forward and aft drag strut 200. 600, 650.

member The laces 110 may be a nylon cord, for example. fairings The fairings are secured to the forward and Grommets may be provided along adjacent edges 106, 108 aft drag struts of the landing gear in the manner described for receiving the laces 110. Other tightening and retaining above. As canbe seen in FIG. 25, an inner girt 651 can be used 55 650 660 means also may be used such as straps, buckles, or the like. An to secure the inflatable fairing to the strut and an outer inflation tube 134 is disposed between the inner girt 120 and girt 652 can be used to provide the shape to the fairing. The outer girt 130 on at least one side of the structural member construction of the outer girt 652 preferably is the same as that 200. 19 20.

Preferably the inflation tube is positioned opposite the of the outer girt 130 shown in FIGS. and The inner girt laces 110. One ormore hoses 104 is usedto supply and extract 651 can be secured to the strut 660 using conventional meth- air from the inflation tube 134. When the inflation tube 134 is 60 ods such as a cord to lace together the separation 655 in the inflated between the inner girt 120 and outer girt 130, the inner and outer girts 651, 652.

outer girt 130 takes on an enhanced aerodynamic profile like As shown in FIGS. 17, 22 and 24, a door panel fairing 640 that shown in FIG. 19. More than one inflation tube 134 can be extends between a forward edge 641 of the landing gear door used between the inner and outer girts 120,130 to provide the panel and a side or edge 643 of the main strut fairing 540. The fairing 100 with a desired shape when inflated. The inner girt 65 door panel fairing 640 can be attached to the door panel edge 120 secures the inflatable fairing to the structure 200, while 641 and the main strut fairing 540 by any suitable connector the outer girt 130 is used to provide the shape of the fairing. or adhesive. For example, the door panel fairing 640 can be

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attached to the door edge 641 with mechanical fasteners such 3. The deployable landing gear truck fairing according to as rivets (not shown), and can be attached to the main strut claim 2, wherein the rising front portion is part of the forward fairing 540 by stitching, adhesives, hook and loop fasteners, assembly.

or the like. Girt fabric panels 640 can be bonded on the 4. The deployable landing gear truck fairing according to leading and trailing edges 641 of the landing gear door to 5 claim 2, wherein forward and aft assemblies are separable provide a smooth transition from the door edge to the main from one another.

strut inflatable fairing. The down stream edge of the panel is 5. The deployable landing gear truck fairing according to attached to the main strut fairing 540 using conventional claim 2, wherein the center seal is affixed to only one of the means, such as by bonding, Velcro® hook and loop fasteners, forward and aft assemblies.

etc. When the main strut fairing 540 is inflated, the door 6. The deployable landing gear truck fairing according to panel(s) 640 will form an aerodynamic shape to reduce noise. claim 2, wherein, when the truck fairing is mounted on In certain applications where the tension in the panel(s) 640 is deployable landing gear of an aircraft, the forward and aft not sufficient to take the air loads, the panels) 640 may be assemblies move toward one another when the aircraft takes replaced with an inflatable door panel (not shown) that is 15 off, thereby compressing the center seal.

constructed like the inflatable fairings described above, and is 7. The deployable landing gear truck fairing according to capable of withstanding the air loads. claim 2, wherein at least one of the forward assembly and the FIG. 18 depicts an inflatable torque link fairing 620. The aft assembly comprises an upper shield plate spaced apart inflatable torque link fairing 620 surrounds the torque link of from a lower shield plate.

a landing gear and provides this portion of the landing gear 20 8. The deployable landing gear truck fairing according to with a smooth, aerodynamic shape. The torque link fairing claim 7, further comprising a weight bearing spacer between 620 may be attached to a top surface 582 of a truck fairing 580 the upper and lower shield plates.

that underlies the torque link fairing 620. The torque link 9. The deployable landing gear truck fairing according to fairing 620 is designed to cover the torque link without claim 8, wherein the weight bearing spacer is positioned impairing the normal movement of the torque link when the 25 beneath a support mounted on an upper side of the fairing.

airplane lands. As shown in FIG. 17, and as further shown in 10. The deployable landing gear truck fairing according to FIGS. 18, 21, 23 and 24, a torque link fairing panel 630 is claim 7, wherein a first portion of the compliant edge occu- configured to wrap around a lower forward portion of the pies a region between the upper and lower shield plates, and main strut of the landing gear and to extend afterward over a second portion of the compliant edge projects laterally each side of the inflated torque link fairing 620. The torque 30 outward from said region between the upper and lower shield link fairing panel 630 may be attached to the sides of the plates.

torque link fairing 620 by any suitable fastener or fasteners, 11. The deployable landing gear truck fairing according to such as hook and loop fasteners. The torque link fairing panel claim 8, further comprising a weight bearing spacer between 630 is constructed of a suitable fabric that can be collapsed or the upper and lower shield plates, wherein the first portion of compressed to permit relative vertical motion between the 35 the compliant edge is laterally outward of the weight bearing truck and strut of the landing gear.

spacer.

While preferred embodiments of the present invention 12. The deployable landing gear truck fairing according to have been described above, it is to be understood that any and claim 1, wherein the compliant edge comprises one from the all equivalent realizations of the present invention are group consisting of rubber or fabric stripping, fiberreinforced included within the scope and spirit thereof. Thus, the 4o rubber, nylon brush, spring steel or an inflatable bladder.

embodiments depicted are presented by way of example only 13. The deployable landing gear truck fairing according to and are not intended as limitations upon the present invention.

claim 1, wherein the compliant edge comprises a soft rubber While particular embodiments of the invention have been or an elastomeric material.

described and shown, it will be understood by those of ordi- 14. The deployable landing gear truck fairing according to nary skill in this art that the present invention is not limited 45 claim 1, wherein: thereto since many modifications can be made. Therefore, it is the elongated body comprises a forward assembly and an contemplated that any and all such embodiments are included aft assembly; in the present invention as may fall within the literal or the first lateral edge comprises adjacent first and second equivalent scope of the appended claims.

lateral edge portions on a first side of the fairing, the first 50 lateral edge portion being associated with the forward We claim: assembly and the second lateral edge portion being asso- 1.A deployable landing gear truck fairing for a deployable ciated with the aft assembly; and landing gear truck having aft, underside, and forward por- the second lateral edge comprises adjacent third and fourth tions, comprising: lateral edge portions on a second side of the fairing, the an elongated body connected to a rising front portion, the third lateral edge portion being associated with the for- elongated body and rising front portion capable of par- ward assembly and the fourth lateral edge portion being tially covering at least the underside and forward por- associated with the aft assembly.

15. The deployable landing gear truck fairing according to tions of the deployable landing gear truck, the elongated body having first and second lateral edges; and claim 14, further comprising: first and second compliant edges affixed to the correspond- 60 a first compliant edge portion affixed to the first lateral edge ing first and second lateral edges. portion; 2. The deployable landing gear truck fairing according to • second compliant edge portion affixed to the second claim 1, wherein the elongated body comprises: lateral edge portion; • forward assembly and an aft assembly; and • third compliant edge portion affixed to the third lateral • center seal extending transverse to a direction of the 65 edge portion; and elongated body and positioned between the forward and • fourth compliant edge portion affixed to the fourth lateral aft assemblies. edge portion,

US 7,954,757 B2

17 18

such that the first and second compliant edge portions are assemblies move toward one another when the aircraft adjacent to one another and the third and fourth compli- takes off, thereby compressing the center seal.

ant edge portions are adjacent to one another. 25. The deployable landing gear truck fairing according to 16. The deployable landing gear truck fairing according to claim 24, wherein the rising front portion is part of the for- claim 15, wherein, when the truck fairing is mounted on 5 ward assembly.

deployable landing gear of an aircraft, adjacent compliant 26. The deployable landing gear truck fairing according to edge portions are: claim 24, wherein forward and aft assemblies are separable spaced apart from one another by a first distance when the from one another.

aircraft is on the ground; and 27. The deployable landing gear truck fairing according to move closer to one another when the aircraft is not on the io claim 24, wherein the center seal is affixed to only one of the ground. forward and aft assemblies.

17. The deployable landing gear truck fairing according to 28. A deployable landing gear truck fairing for a deploy- claim 16, wherein opposing surfaces of adjacent compliant able landing gear of an aircraft, comprising: edge portions abut one another when the aircraft is not on the an elongated body connected to a rising front portion, the ground. 15 elongated body having a forward assembly, an aft 18. The deployable landing gear truck fairing according to assembly, and first and second lateral edges; claim 16, wherein opposing surfaces of adjacent compliant the first lateral edge comprises adjacent first and second edge portions are angled. lateral edge portions on a first side of the fairing, the first 19. A deployable landing gear truck fairing, comprising: lateral edge portion being associated with the forward a pair of adjacent fairing sections defining a forward 20 assembly and the second lateral edge portion being asso- assembly and an aft assembly suitable for mounting on a ciated with the aft assembly; and truck, each assembly having a first side and a second the second lateral edge comprises adjacent third and fourth side; lateral edge portions on a second side of the fairing, the a center seal affixed to at least one of the forward and aft third lateral edge portion being associated with the for- assemblies and positioned between the two assemblies; 25 ward assembly and the fourth lateral edge portion being adjacent first and second compliant edge portions affixedto associated with the aft assembly; and the first side of the forward and aft assemblies; and first and second compliant edges affixed corresponding adjacent third and fourth compliant edge portions affixed to first and second lateral edges.

the second side of the forward and aft assemblies. 29. The deployable landing gear truck fairing according to 20. The deployable landing gear truck fairing according to 30 claim 28, further comprising: claim 19, wherein, when the truck fairing is mounted on a first compliant edge portion affixed to the first lateral edge deployable landing gear of an aircraft, adjacent compliant portion; edge portions are: a second compliant edge portion affixed to the second spaced apart from one another by a first distance when the lateral edge portion; aircraft is on the ground; and 35 a third compliant edge portion affixed to the third lateral move closer to one another when the aircraft is not on the edge portion; and ground. a fourth compliant edge portion affixed to the fourth lateral 21. The deployable landing gear truck fairing according to edge portion, claim 20, wherein opposing surfaces of adjacent compliant such that the first and second compliant edge portions are edge portions abut one another when the aircraft is not on the 40 adjacent to one another and the third and fourth compli- ground. ant edge portions are adjacent to one another.

22. The deployable landing gear truck fairing according to 30. The deployable landing gear truck fairing according to claim 21, wherein opposing surfaces of adjacent compliant claim 29, wherein, when the truck fairing is mounted on the edge portions are angled. deployable landing gear of an aircraft, adjacent compliant 23. The deployable landing gear truck fairing according to 45 edge portions are: claim 19, further comprising a brake cover fairing. spaced apart from one another by a first distance when the 24. A deployable landing gear truck fairing for a deploy- aircraft is on the ground; and able landing gear of an aircraft, comprising: move closer to one another when the aircraft is not on the an elongated body connected to a rising front portion, the ground.

elongated body having a forward assembly and an aft 50 31. The deployable landing gear truck fairing according to assembly, a center seal extending transverse to a direc- claim 30, wherein opposing surfaces of adjacent compliant tion of the elongated body and positioned between the edge portions abut one another when the aircraft is not on the forward and aft assemblies, and first and second lateral ground.

edges; and 32. The deployable landing gear truck fairing according to first and second compliant edges affixed to corresponding claim 31, wherein opposing surfaces of adjacent compliant fast and second lateral edges; edge portions are angled.

wherein, when the truck fairing is mounted on the deploy- able landing gear of an aircraft, the forward and aft