US3131891A

US3131891A - Retractable undercarriage for airplanes

Info

Publication number: US3131891A
Application number: US173953A
Authority: US
Inventors: Lallemant Pierre Martin Joseph
Original assignee: Hispano Suiza Lallemant SA
Current assignee: Hispano Suiza Lallemant SA
Priority date: 1961-08-08
Filing date: 1962-02-19
Publication date: 1964-05-05
Anticipated expiration: 1981-05-05

Description

y 5, 1964 P. M. J. LALLEMANT 3,131,891

RETRACTABLE UNDERCARRIAGE FOR AIRPLANES Filed Feb. 19, 1962 2 Sheets-Sheet 1 Fig.1

I INVENTUR ATTORNEY y 1954 P. MQJ. LALLEMANT 3,

RETRACTABLE UNDERCARRIAGE FOR AIRPLANES Filed Feb. 19, 1962 2 Sheets-Sheet 2 INVENTOR ATTORNEY United States Patent "ice r. 3,131,891 RETRACTABLE UNDERCARRIAGE FOR Pierre Martin Joseph Lallemant, Pott-Marly, France, as- "signo'r to Societe Hispano Suiia Lallemant, Rois-Colomb'es,'Fran'ce, aspciety'of'Fr'ance v Filed-Feb. 19, '1962, Ser. No. 173,953 Claimspriority, application FranceAiig. s, 1951 3 Claims. "'(Cl. 244-402) V The present invention relates to undercarriages for airplanes, comprising'struts'to be retracted individually into the airframe'of the airplane, for instance into the fuselageor into nacell'e's incorporated in the wings 'of the airplane. The invention is more'e's p'ecially but'notexclusively concerned with airplanes'of the 'high'wing type, wherethe struts of the main landing gear are to be retracted 'into nacelles incorporated in the high wing'of the airplane.

The chief object of this invention is to provide an undercarriage of the above mentioned type which is better adapted to meet the requirements of practice than those known up to this-time,'in particular'concerning the space that is occupied in retracted position.

This invention fela'fe's to the case where the undercarriagecomp'rises at -leastoiies'trut including a shockabsorber pivoted at its lower end to the support of the wheel belonging to said strut and at its upper end to a rigid connecting member disposed substantially in vertical alinement with said shock-absorber and itself pivoted to the airframe of the airplane and the invention is characterized in that retraction of said strut is obtained by means of at least one telescopic fluid actuator the ends of which are pivoted respectively to the airframe of the airplane and to said rigid connecting element.

A prefered embodiment of this invention will be here after described with reference to the appended drawings, given merely by way of example, and in which:

FIG. 1 is a side view of an undercarriage according to the invention, shown in the down position;

FIG. 2 is a similar view showing the undercarriage in partly retracted position;

FIG. 3 is a similar view showing the undercarriage "in wholly retracted position.

In the embodiment of the invention illustrated by the drawings an undercarriage is intended to be retracted into a nacelle 1 incorporated in one of the half-wings of the airplane.

The main strut of the undercarriage comprises a shockabsorber 2, preferably an oleo-pneumatic shock-absorber of the telescopic type, the lower end of which is pivoted at A to the support of wheel (of pair of wheels) 3 corresponding to this strut and the upper end of which is pivoted at B to a rigid connecting element 4 extending substantially in line with said shock-absorber 2 when the undercarriage is in the down position, this element 4 being itself pivoted at C to the airframe of the airplane. Preferably pivot points A, B and C are at least approximately located on a vertical line when the undercarriage is in the down position.

In the embodiment of the invention illustrated by the drawings, interconnecting element 4 is in the form of a piece having a general triangular outline.

Wheel support 5 is preferably arranged, as shown, so that the undercarriage is of the so-called indirect type, said support consisting, as shown, of a lever 5 at one end of which wheel 3 is journalled. To the other end of lever 5 there is pivoted, at B, a rod 6 the upper end of which is pivoted at E to the airframe of the airplane. Said rod 6 is connected to element 4 through a rigid link 7 one end of which is pivoted at F to an intermediate 3,131,891 Patented May 5, 1

point of rod G'and'the other end of which is pivoted to element 4at a 'point G. Preferably, a's shownby the drawings, this'point'G'isloca ted, with respect to'line A, B, C, 'onthe sidethereofopposed to that toward which wheel3'is to'be lifted. The point A where 's'hock absorber 2 is pivoted 'to the wheel supporting lever 5 is located b etweenthe ends of said lever '5.

Now, according 'to the main feature of thisinvention, retraction of the und erc'arria'geis effected byr'neans of at leastone fluid actuator, preferablya hydraulic one, one of the ends of which is pivoted to the airframe and the 'otherend of which is pivoted to connectinglement 4, this'actuator8, which is preferably of the double "acting'type,'b'eing arranged in "such manner that, during the retraction operation, it "causes connecting element "4, "to pivotaboutpoint C in adirection such that this move ment produces an'upward'rtraction "of the deformable system A, B, C, D, E, F.

Preferably, in order to reduce as much as possible the space occupied by the undercarriage in retracted pbsi tion, actuator S is mountedrso as to exert 'a pulling thrust during the retraction of the undercarriage; "For this purpose sai d actuator must be located, with respect to line A, B, C, on the side thereof opposed to that toward which wheel 3 must be moved upwardly. Actuator 8 is pivoted at one end, at H, to the airframe and at I to connecting element 4.

When comparing FIG. 2 (partly retracted position) and FIG. 3 (wholly retracted position) with FIG. 1 the following points should be noted:

(a) retraction of the undercarriage is accompanied by a substantial reduction of its length so that the space necessary for housing the retracted undercarriage is reduced with respect to the relatively great height of this undercarriage in the down position, made necessary by the fact that the wing is a high wing;

(12) the whole of the lifting mechanism is constantly located in a reduced space extending approximately above the corresponding wheel, which has but a small displacement in the longitudinal direction of the airplane during the retraction operation; and

(c) actuator 8, due to the substantial alinement of points A, B, C withstands practically but a small portion of the efforts applied to the wheel when the aircraft is taxiing on the ground.

Of course the undercarriage above described may be fitted with all suitable safety devices, such for instance as a device for locldng the undercarriage in the down position (acting for instance upon the actuator), an electric signalling device operated by the locking device and indicating to the pilot that the undercarriage is truly in down position for landing, a device for cutting OK the feed of liquid to the actuator when the undercarriage is in the down position and so on.

Of course the invention is not limited to the particular embodiment thereof shown by the drawings.

What I claim is:

1. For use with an airplane fixed structure, an undercarriage unit which comprises, in combination, a rigid member pivoted to said airplane structure about a single first axis transverse to the fore-and-aft direction of the airplane, a wheel, a rigid wheel support, a shock absorbing strut pivoted at one end to said rigid member about a single second axis and at the other end to said wheel support about a single third axis, respectively, both of said second and third axes being transverse to the foremovable with respect to each other, one of said elements being pivoted to said airplane structure and the other of said elements being pivoted to said rigid member about a fourth single axis and a fifth single axis, respectively, both transverse to the'fore-and-taft direction of the airplane, said wheel support being a lever pivotable about said third axis, saidwheel being journalled in said lever at one end thereof, a rod pivoted at one end to the said lever andtat the other end directly to said airplane structure about respective axes transverse to the fore-and-aft direction 'ofthe airplane, and a rigid link pivoted "at one end toan intermediate point of said rod and at the other end to said rigid member about respective axes transverse to the fore-and-aft direction of the airplane. 2;. For use with an'airplane fixed structure, an undercarriage unit which comprises, in combination, a rigid 7 member pivoted to said airplane structure about a single first axis'transverse to the fore-and-aft direction of the airplane, a wheel, a rigid wheel support, a shock-absorbing strut pivoted at one end to said rigid member-about v a single second axis and at the other end to said wheel support about a single third axis, respectively, both of versely tthereto when th e undercarriage unit is in the movable with respect to each other, one of said elements being pivoted to said airplane structure and the other of said elements being pivoted to said rigid member about a single fourth axis and a single fifth axis, respectively, both transverse to the fore-and-aft direction of the airplane, said wheel support being a lever extending on oppothe airplane, said first, second andthird axes being 10-" V cated in a common vertical plane transverse to the -foreand-aft direction of the airplane when the undercarriage is in-the down position.

3. An undercarriage according 'to claim -2 wherein I said hydraulic actuator is located, with respect to the common plane of the first, second and third axes, on the side thereof opposed to that toward which said wheel i is moved upwardly when the undercarriage is retracted.

down position, a hydraulic actuator for retracting said I strut, said actuator including two elements telescopically References Cited in the file of this patent V UNITED STATES PATENTS 2,506,178 I Shaw May 2, 1950' 2,982,500 Lucien Ma a, 1961

Claims

1. FOR USE WITH AN AIRPLANE FIXED STRUCTURE, AN UNDERCARRIAGE UNIT WHICH COMPRISES, IN COMBINATION, A RIGID MEMBER PIVOTED TO SAID AIRPLANE STRUCTURE ABOUT A SINGLE FIRST AXIS TRANSVERSE TO THE FORE-AND-AFT DIRECTION OF THE AIRPLANE, A WHEEL, A RIGID WHEEL SUPPORT, A SHOCK ABSORBING STRUT PIVOTED AT ONE END TO SAID RIGID MEMBER ABOUT A SINGLE SECOND AXIS AND AT THE OTHER END TO SAID WHEEL SUPPORT ABOUT A SINGLE THIRD AXIS, RESPECTIVELY, BOTH OF SAID SECOND AND THIRD AXES BEING TRANSVERSE TO THE FOREAND-AFT DIRECTION OF THE AIRPLANE, SAID STRUT EXTENDING ALONG A LINE INTERSECTING SAID FIRST AND SECOND AXES TRANSVERSELY THERETO WHEN THE UNDERCARRIAGE UNIT IS IN THE DOWN POSITION, A HYDRAULIC ACTUATOR FOR RETRACTING SAID STRUT, SAID ACTUATOR INCLUDING TWO ELEMENTS TELESCOPICALLY MOVABLE WITH RESPECT TO EACH OTHER, ONE OF SAID ELEMENTS BEING PIVOTED TO SAID AIRPLANE STRUCTURE AND THE OTHER OF SAID ELEMENTS BEING PIVOTED TO SAID RIGID MEMBER ABOUT A FOURTH SINGLE AXIS AND A FIFTH SINGLE AXIS, RESPECTIVELY, BOTH TRANSVERSE TO THE FORE-AND-AFT DIRECTION OF THE AIRPLANE, SAID WHEEL SUPPORT BEING A LEVER PIVOTABLE ABOUT SAID THIRD AXIS, SAID WHEEL BEING JOURNALLED IN SAID LEVER AT ONE END THEREOF, A ROD PIVOTED AT ONE END TO THE SAID LEVER AND AT THE OTHER END DIRECTLY TO SAID AIRPLANE STRUCTURE ABOUT RESPECTIVE AXES TRANSVERSE TO THE FORE-AND-AFT DIRECTION OF THE AIRPLANE, AND A RIGID LINK PIVOTED AT ONE END TO AN INTERMEDIATE POINT OF SAID ROD AND AT THE OTHER END TO SAID RIGID MEMBER ABOUT RESPECTIVE AXES TRANSVERSE TO THE FORE-AND-AFT DIRECTION OF THE AIRPLANE.