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Патент USA US2403835

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July 9, 1946.’-
_‘ Filed Dec. 16. 1941
Patented July 9, 1945.
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)
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
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.
~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
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
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
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
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.
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
same plane,the1 combination of journal mounts
per dog becomes disengaged from ' the locking
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
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
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
relationship in their retracted positions,
planes to tandem positions substantially in the
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
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
rearwardly about their respective skewed mount
of symmetry of the aircraft.
ing axes into tandem disposed positions along the
said longitudinal plane of symmetry,
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