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July 9, 1946.’- > _ J. G. VILLEPIGUE ' 2,403,835 RETRACTABLE LANDING GEAR ‘ _‘ Filed Dec. 16. 1941 _J. G. VILLEPIGUE. ' INVENTOR. .BY Ll._ I ’ . ' HIS PATENT ATTORNEY. , Patented July 9, 1945. 2,403,835 ‘TED’ STATES * _ 8 OFFICE‘, ‘ 2,403,835.... 7 RETRACTABLE LANDING cam Julius G. Villepigue; ‘Inglewood; Calif., assignor to North American Aviation, Inc., Inglewood, Calif.,'a corporation of Delaware I 2 .. ‘ Application December 16, 1941, 'SeriallNo. 423,161 _11 Claims. (Cl. 244—102) . . . 1 This invention relates to retractable landing Q gears and has particular reference to‘ an im proved landing gear arrangement which permits the landing gear units to be folded up into an aircraft body portion with'the landing wheels or ground engagers disposed'in a tandem relation‘ ' ship’with respect to the fore and aft axis ofthe aircraft.’ . i ‘ ' " I > 2 , wheel‘ be fully housed. Since‘ the main landin gear of a conventional airplane consists of two wheel ,units‘,‘ it thus becomes necessary to adopt some means by which the gear units can be re tracted to 'lie in tandem along the length of the fuselage. It is also most desirable to have them lie ?at in arplane substantiallylparallel tofthe horizontal. Thusstill another object is tov pro ' 3 Accordingly, one of the principal objects of this ‘ - vide'avretractiye, arrangement which causes ro invention is ‘to provide a landing gear‘capable. 10 tation'of the landing'wheels from one plane to another during the time the landing gear-is being of movement from the usual extended position» _ in which the wheels are in laterally spaced ar moved from‘ one extreme position to the other.‘ rangement parallel to the fore and. aft axis of the aircraft, to a retracted position'in which they lie flat and one behind the. other, in a fore and aft sense. 'This is desirable in a landing gear designed especially for use in modern high speed form a‘ main landing gear installation, which Another principal object is to‘ providea land ing gear unit of the'type employedin pairsto. unit is adapted to be used interchangeably in the installation either as the right hand‘unit or as the left hand unit of the pair. ' aircraftrin which every effort is made to reduce Still another object is to produce an inter thereby reducing the attendantdrag to the lowest 20 changeable landing gear unit of the retractable type having a skewed journal, mounting adapted possible degree. In attaining. ‘airplane designs to cause the- unit to retract forwardly or rear of decreased aerodynamic resistance; thedepth ' the frontal area’v of the body for the purpose of of the wing and the cross section of the fuselage have been ‘gradually reduced to the point where wardly of . a I mean :line depending on .whether the unit is swung inone direction or .the other ' the fuselage encompasses barely'enough space to 25 ‘about itsmounting pivot. ~ = e ‘ - - ~Other subsidiary objects are to provide‘ a, land contain the body of the pilot in a sitting posture. ing gear installation comprised of units adapted It is even contemplated that for this and other to accomplish the foregoing desired results while‘ reasons it may soon be necessary to dispose the at the same time remaining of simple construc pilot entirely in" a prone position. With space . considerations so important, it becomesneces 30 tion and reliable operation. With the speci?ed general objects and results sary to take advantage of all available space to in View as well as others which will become ap the fullest extent and ‘even to devise new. ways parent during the course of the following de-. of utilizing such existing space to house the in scription, this invention consists in certain novel dispensable auxiliaries of airplanes. By judicious design of the fuselage-wing com 35 features of design, construction and arrangement » of elements which results‘ in a certain method of bination, where the airplane cross section is esstowage of a retracted. landing gear,» all as Will pecially small,hand'by a specially designed re tractive arrangement as provided by this inven tion, ‘it still remains possible to’ completely house the landing ,gear elements within the aircraft ’ be more‘ particularly referred to'and speci?ed hereinafter. . . , . . Referring to the accompanying drawing; structure when in the retracted position. There fore, it‘ is a'further object of this invention to _ Fig. 1 is a perspective view of the underside of anairplane . ?tted with a landing gear installa utilize the‘ available-space in an aircraft in an tion according to this "invention; _ ‘ 1 Fig. 2 is-a frontal view ofa portion of the same arrangement‘ adapted to receive and house the landing gear wheels partly within the aircraft 45 airplane and landing gear combination; and ’ wing and partly within its fuselage; : .7 g ' ' Carried to the full extent represented by the Fig. 2A is, a detailed view of a portion of Fig, 2 showing the strut rotation and locking means. ' In the ?gures there is shown an aircraft III de present arrangement, this reduction of the cross section of. the aircraft results in a-fuselage too" picted as allow wing monoplane and comprised narrow adjacent the undersurface to enclose a 60 of a fuselage I! supported by a Wing l4 and ?tted With an empennage I6. The fuselage of this air landing wheel of proper size while at the same plane isintended to be representative‘ of the type timethe wing is too shallow in' depth‘ at any point to provide'the required room. Only by having-an- extremely small cross-sectional area utilizing the combined space afforded, within the as is now found in high-speed military ?ghting wing and lower part ofthe fuselage can a single 55 planes where the fuselage section is only as large 2,403,835 3 4 as is required to enclose the propulsive power plant or the body of the pilot, whichever may and forward motion with the result that the wheels 24 move from the position of lateral align have the larger cross section. At the same time, the wing has a plan form of minimum area as lateral sense.‘ As before explained, the'fuselage well as being of minimum depth, This is the type of airplane for which the present landing gear l2 and wing M can be of an extremely small cross-section such that the wing-fuselage com arrangement is particularly adapted although it bination affords only suihcient cross-sectional does not follow that the present inventivev ar rangement is limited to employment in such an area to fully'accommodate the cross-sectional airplane as it could also be employed in replace ciated supporting structure disposed transversely ment of more conventional landing gear types; therein, such that it would be entirely impossible for the WhBQIS'tO be fully housed in a side by side In the installation shown, the main. landing‘ gear equipment consists of right and left hand units l8 and 29 each of which is» an exactdupli cate of the other except for'the fact that they" are mounted on opposite sides of the fuselage center line. Each of these- consists of. a single; cantilever strut 22 adapted to carry a ground_en gager or landing Wheel. 24 and for the sake“ of" symmetry the units are disposed so that the wheel elements-have corresponding‘ facesnplace‘d in‘ op position. Each‘ unit is formed of tubular elements ment to one in which they are out of line in a bulk of one of the landing wheels and its asso or lateral relationship. , Thus both Wheels can be fully housed by having the .wheels arriveat a tandem disposition as a re sult of the retractive movements. With the skew arrangement of the. axes A—A and B—B, the wheels are caused to pass each other during re traction and to ?nally lie within the outline of the airplane, one behind the other adjacent to the fore and‘ aft centerlineéottheairplane, as is evident in Fig; 1. Also;v as’ isrshowrr in .the draw ing, the lateral spacing ‘of. thepivotiaxes issuch in a two-part telescopic construction so that as would cause the landing: wheels to interfere landing shocks can be absorbed by a more or less conventional‘ oleo shock absorber built into the 25 with each other during retractionwere itnot for the skew arrangement of/ the retraction axes strut; and each is further equipped with'nut which prevents. such interference. In other cracker type torque links Z‘S'which serve to keep words, the lateral spacing between the pivot axes the strut sections from twisting relatively t’oeach is less than the combinedilengths of’ the landing other,‘ whereby the landing wheel is‘ retained in proper alignmentwith respect to the axis of‘ the 30 gear units‘measured‘ from theipivot pointto'the opposite side'of the' Wheel. This is contrary to airplane. the mensural relationships‘ found in;conventional The landing/gear units are mounted on pivot landing gears of the-inwardly:retractingtype. journals 28' and 30‘, respectively, so as to hang be ‘In order for-the landing gear: unitsto'passrint'o low the lower surface of" the wing I4" when the the interior of the ‘airplanethe lower skin sur gear is in the extended attitude. These journals face is suitably cut-out forthe purposeito‘pro are ?xed‘to'the'interior structure of the wing by vide individual wells and; these maybe provided any Well known and convenient means but ac with closures normally providing. a' ?ush:continu cording to this invention’ they are so disposed ation of the? undersurfa‘ce of the: airplane. Such as to'have their pivot axes A——A and B—-B1 in a closures and the mechanism for" operating" them non-parallel‘ relationship with the fore and aft ' form no part of ‘this invention, axis of the airplane on which they’ are installed. In certain fuselage arrangements‘ the" simple Thus in the arrangement shown, the axis B‘—-B, journal mounting shown in‘ the drawings might if-“extend‘ed, would intersect the vertical‘ plane not be su?icient to bring the'il'an'ding‘wheels‘into containing the fore and- aft axis‘ in the rear‘por tion of the airplane somewhere aft of the-center » of‘ gravity whilethe axis A-—A if‘ similarly ex tended, would intersect the same plane in: the front portion ahead of the center of gravity. Furthermore, each pivot journal hasa project ing arm 32 attached rigidly thereto, to which is ' pivotally connected the piston rod 34 of a hy draulic cylinder 36 which'latter is pivotally at tached as at 38 to the interior‘structure of the wing. Pressure ?uid‘: applied selectivelyto oppo site ends of the cylinders‘ is effective to swing the ; landing gear units above their respective pivot axes B-B and A-—A as is well known in the art. Because such pressure systems are in common use, it is thought to be unnecessary to eithershow or further describe such a system in connection with the present invention. However, operation a retracted‘ position in’ the most: desirable attitude for stowage due either to' the curvature: of the undersurface of- the Wing andfuse'lage or'toin terference with‘ other parts andtequipment which may be'housed' in these-portions of'the-aircraft". Accordingly, there: is provided a secondary'means; various forms of which have previously been sug gested in retractable landing‘ gears, to impart to the cylinder portion ofithe main strut' |.8- axial rotation relative to the journal‘ ?tting 281 The mechanism bywhichthissecond‘aiy move ment is obtained is shown in themodi?cation in 2A which is a corresponding front view of the right wing portion of the same airplane shown inFig. 2. A‘ suitable thrust bearing surface 58a is provided between the main strut I8‘ and the pivot‘ ?tting 28 and’a toothed gearsegm'ent-AU' is ?xedly attached to the strut l8’ below the said of the retracting mechanism serves to swing the thrust bearing surface; A'rack bar 42'; provided separate landing gear units from the extended with a marginal cam’ strip 44', is attached to the position, in which the landing wheels 24 are dis posed in lateral alignment in vertical planes sym~ 65 wing structure by the fastenings 46 in a position in which it will be engaged by, the gear‘segnient metrically arranged on‘ either side of the fore and lit! as the landing gear passes through the ?nal aft‘axis of the airplane and parallel thereto, up stage of its retractive' movement. A lock unit 48 ward and‘ inward to the retracted position, is pivotally mounted at ill-adjacent- the upper , Due‘ to-the non-parallel or skew disposition of the‘ pivot axes A—A and B—B, the landing gear 70 extremity of the strut lBand has" oppositely, ex tending dog' portions 521, normally wedged into the units‘are also caused to have a third component of locking condition by'the spring 573. The lower motionbut in the respective units these third com dog portion is adapted to engage'the cam strip ponents are oppositely directed. That is, the unit Mas- the strut is retracted; thereby rotating the 20* partakes of inward, upward and rearward mo tion While the unit I8~ partakes of inward, upward dog element about the-pivot 50“such that the up 2,403,835’ 5 ‘ 7 for each of ‘said units‘ disposed on, axes skewed, with respect to the said spaced positions, means adapted to cause rotation of each landing gear unit about its respective skewed axis-and second lug 28a; The toothed gear segment and rack bar accordingly; rotate the strut ' I8 axially with respect, to the journal ?tting 28 as the lock unit is disengaged to free theaxial, relationship be means adapted to cause rotation of each of said gear units about an axis intersecting the skew tween, these strut portions, thereby permitting the wheel to :be tilted to any desired angle. a ' I The above described meansvv for imparting axial axis thereof. . I ‘ 3. In a retractable landing gear, a pairof inde rotation'to the strut during retraction is but one pendent cantilever strut units, ground‘ engaging of a number of satisfactory mechanisms avail able for this‘ purpose. The present invention is, therefore, not speci?cally limited to an axial ro tation mechanism of the type shown and de means carried by each of said strut units, a jour nal mounting for each of said strut units equi distantly disposed‘ on opposite sides/of the ‘fore scribed nor is it to be limited to the speci?c ar rangement for locking the-mainstrutito its pivot ?tting in the extended position and unlocking a , thesame- during retraction to permit of the axial rotation; From the present disclosure and de.. ' scription it will beobserved" that there is provided a retractable landing gear installation in which 6 same plane,the1 combination of journal mounts per dog becomes disengaged from ' the locking 20 each wheel moves from its operative position in a vertical plane transverse tothewing, to aposi tion in a horizontal plane parallel to the'under and aft plane :of symmetry on axes parallel to each other but angularly-intersecting the said plane of symmetry at separate points, and means adapted to rotate each strut unit about its said journal mounting,v said journal mountings being adapted to cause pivotation of the said strut units ,from a fore and aft retracted disposition of the said ground-engaging means in substantially‘ the sameiplane inethe region of said plane of symme try to' extended disposition in substantially par allel' planes on opposite sides of said longitudinal surfacelof the wing 'orithe fuselage, or to any angle oftilt of the wheels,'and vice versa. It should be further evident that there has been plane ofsymmetry.‘ ' , ‘ 4. In a retractable landing gear for an aircraft, a pair of llaterally disposed cantilever strut units; provided alanding gear, unit which can 'be em ground‘eng'aging means carried by each said strut ' ployed interchangeably in pairs in consequence unit. pivot mountings for said strut unitsrequi of. which the problem of supply has been greatly simpli?ed. This is particularly true in the supply 30 distantlyidisposed with their axes of pivotation ‘lying in a horizontal common’ plane on laterally of rrepair units, for. with the present interchange opposite sides ofvthe longitudinal plane of syme I able'unit ‘it is only necessary to maintaina stock metry or the aircraft, the'axes of the said pivots of one type of unit insteadof a stock of two types of structurallyv di?erent'units which could only ' _ beinglang‘ul'arlyl disposed in vsuch manner that ' they-jiintersect" said ‘reference ' plane of symmetry be used as right or left'hand units exclusively; ‘ at spaced points fore- and aft of the transverse The.airplane which has been selected: for illus li'neoi‘ saidlateral disposition, and means adapted trative purposes only has been shown as the con to retractively rotate said units aboutlthe said axes such thatv the ‘respective vground engaging ventional type in which a'tail wheel or skidwould be provided beneath the'empennage. The present invention is, however, equally applicable'to air a means adopt fore and aft'tandem positions proxi- ' mate ‘to’ said plane of'symmetry of the aircraft. 5. A retractable landing gear arrangement for an aircraft provided-with a pair of landing units laterally disposed in their extended positions with craft. In the embodiment shown as provided for ‘ a tail wheel, the center of gravity of the airplane _=-' respect to the longitudinal plane of symmetry of said" aircraft, each I said‘ landing unit provided would normally lieslightly aft of the transverse with a ground engaging element, mounting means line joining the journalled upper ends of the oleo for ‘said laterally disposed landing units having cylinders 22, In the case of a nose wheeltype axes‘ asymmetrically but equidistantly located landing‘gear the strut journals would be disposed somewhat aft of the center of gravity of the air- ‘_ with irespectl't‘o said longitudinalvplane/of sym metry, irneans‘to ? retract said laterally disposed units such ‘that-their, ground engaging elements While there has been illustrated and described craft having a nose wheel landing gear in which case the main landing gear struts ‘I 8 and 20 would be located farther aft toward the tail of the air plane. 7 , a particular mechanical embodiment of this in vention, it is to be understood that it is not lim are disposed in -fore andaft tandem relationship ment of parts may be resorted to as come within elements to lie in a substantially common hori along said longitudinal plane of symmetry of the ited to the speci?c form herein described, but 55 aircraft, and further means cooperating with said retracting means to causelsaid ground engaging that certain changes in the shape and arrange- , zontal plane in their said retracted positions. 6. A retractable landing gear arrangement for 1. In an aircraft, a retractable landing gear in 60 an aircraft providedwith a pair of landing units laterally disposed in substantially parallel planes stallation comprising a pair of, individual canti in their extended positions on opposite sides of , lever landing gear units, landing Wheels carried the longitudinal plane of symmetry of the air by each said unit, individual pivot mountings for craft. each said unit provided with ground engag said units disposed on opposite sides of the fore ing elements, each said landing unit having a and aft plane of symmetry of said aircraft on axes pivot axis angularly disposed in such manner that intersecting the plane of symmetry respectively it intersects the longitudinal plane of symmetry fore and aft of the center of gravity of said air of theaircraft at a remotely spaced point in re craft and means adapted to rotate said units spect to the intersection of the other said‘landing ' about the said axes for retraction of said wheels into fore and aft positions in the region. of said 70 unit pivot axis, each said landing unit arranged for its“ retraction inwardly towards the other plane of symmetry. ' landing unit and thelongitudinal plane of sym 2. In a landing gear installation in which land metry of said aircraft in such manner that said ing gear units are arranged for swinging from the scope of the appended claims. What I claim is: , ' ground engaging elements assume a fore and aft spaced extended positions in substantially parallel tandem relationship in their retracted positions, 76 planes to tandem positions substantially in the . 2,403,835 7 8 retracting means to cause said landing units to move between said extended and retracted posi tions, and means initiated by said extension and 9. In a retractable landing gear for aircraft having a wing and a fuselage, said landing gear comprising two like units each provided with ground engaging wheels, means for rotatably mounting the units of said landing gear upon said retraction adapted to impart secondary rotation to said ground engaging elements with respect to said units whereby they lie in a substantially common horizontal plane in their retracted posi tions and in substantially parallel vertical planes in their extended positions. ' '7. In an airplane, including a wing of ?nite thickness and'a fuselage carried thereby, a pair of retractable landing gear units each carrying a wheel, the overall dimension through the axis wing at points equally spaced on opposite sides of the longitudinal plane of symmetry of said fuse lage, the rotational axes of the said mounting means extending in substantial parallelism with respect to each other and being angularly dis posed with respect to‘said longitudinal plane of symmetry, and rotative means for retracting said units toward the said fuselage, the said angular disposition of the said rotational axes causing of each said wheel being greater than the thick ness of said wing, wheel wells disposed in tandem 15 retractive movement of the wheels from their ex with respect to the longitudinal plane of sym tended disposition'in substantially parallel ver metry of the airplane, each said wheel well ex tical planes into a retracted position in a longi tending from the under surface of the wing into tudinally tandem relationship within a substan the said fuselage and parallel pivot means for tially common horizontal plane. each said landing gear unit angularly disposed so 10. In a landing gear installation for an air that their axes intersect the said longitudinal craft, the combination of retractable landing gear plane of symmetry of the airplane at longitudi units, ground‘ engaging wheels carried by said nally spaced points, and means for retracting the units, journal mountings for said'landing gear said landing gear units in such manner that the units equidistantly disposed and with their axes wheels are swung from laterally aligned parallel 25 of pivotation angularly disposed with respect to positions beneath said wing to retracted tandem the longitudinal plane of symmetry of the aircraft positions within the said wheel wells wherein they said axes at the same time lying in a common sub lie on the said longitudinal plane of symmetry of stantially horizontal plane, and means adapted the airplane. ' , to rotate each said landing gear unit about its 8. In an airplane of the low wing monoplane angularly disposed‘journal mounting from a re type including a fuselage carried thereby and re tracted disposition in substantially the same hori tractable landing gear units fitted with landing zontal plane in which said wheels are longitudi wheels, each of said wheels being of an overall nally disposed with respect to each other to a diameter substantially equal to the width of the side-by-side extended disposition in substantially fuselage, said landing gear units having an over parallel planes oppositely disposed and parallel - all‘ thickness through the wheel axis greater than’ with respect to said longitudinal plane of sym the maximum depth of the monoplane wing, the combination of skewed mountings for said land 11. A retractable landing gear arrangement for ‘ ing gear units on axes which are angularly dis an aircraft provided with'a pair of landing units posed so that they intersect the longitudinal plane 40 laterally disposed in their extended positions metry. of symmetry of the airplane at spaced points, said mountings being equally spaced laterally on op posite sides of said longitudinal plane of sym metry, and means to retract said landing gear units from their parallel extended positions sym metrical to said longitudinal plane of symmetry into the space afforded by the combined depths of said fuselage and monoplane wing by causing ' ' equidistantly with respect to the longitudinal plane of symmetry of the aircraft, each said landing‘ unit provided with a ground engaging element, mounting means for said landing units having axes asymmetrically but equidistantly lo cated on'opposites of said longitudinal plane of symmetry and means to retract said laterally disposed units in such manner that their ground one of said units to move upwardly and forwardly engaging elements are disposed when retracted and the other of said units to move upwardly and in a longitudinal relationship along the said plane 50 rearwardly about their respective skewed mount of symmetry of the aircraft. ing axes into tandem disposed positions along the said longitudinal plane of symmetry, JULIUS G. VILLEPIGU'E.