US011530031B2

( 12) United States Patent ( 10 ) Patent No .: US 11,530,031 B2

Allwein et al . (45 ) Date of Patent : Dec. 20 , 2022
( 54 ) FOLDING TRAILING ARM LANDING GEAR ( 58 ) Field of Classification Search
CPC B64C 24/10
( 71 ) Applicant: General Atomics Aeronautical See application file for complete search history .
Systems , Inc. , San Diego , CA (US )
(56) References Cited
( 72 ) Inventors : Michael Joseph Allwein , San Luis
Obispo , CA (US ) ; Caleb Andrew U.S. PATENT DOCUMENTS
Bartels , Escondido , CA (US ); Brian 2,220,546 A 11/1940 Saulnier
Michel Shamblin , Ramona, CA (US ); 2,399,846 A 5/1946 Bachman
James Edward McMillen , Ramona, 2,497,415 A 2/1950 Parker
CA (US ) 2,511,528 A 6/1950 Clark
2,661,171 A 12/1953 Allen
( 73 ) Assignee : General Atomics Aeronautical ( Continued )
Systems , Inc. , San Diego , CA (US )
FOREIGN PATENT DOCUMENTS
( * ) Notice: Subject to any disclaimer, the term of this
patent is extended or adjusted under 35 CN
EP
104354853
0676328
2/2015
10/1995
U.S.C. 154 ( b ) by 102 days .
( Continued )
( 21 ) Appl . No .: 17/196,589
OTHER PUBLICATIONS
(22) Filed : Mar. 9 , 2021
Extended European Search Report issued in European Patent Appli
( 65 ) Prior Publication Data cation 18856103.9 mailed from the European Patent Office dated
US 2021/0188423 A1 Jun . 24 , 2021 Apr. 23 , 2021 .
Related U.S. Application Data (Continued )
( 62 ) Division of application No. 15 / 703,416 , filed on Sep. Primary Examiner Jessica B Wong
13 , 2017 , now Pat . No. 10,967,959 . (74 ) Attorney, Agent, or Firm - Fitch , Even , Tabin &
Flannery LLP
( 51 ) Int . Ci.
B64C 25/10 ( 2006.01 ) ( 57 ) ABSTRACT
B64C 25/26 ( 2006.01 ) A folding trailing arm landing gear assembly having a main
B64C 25/20 (2006.01 ) fitting configured to couple to a hinge positioned at a
B64C 25/12 ( 2006.01) proximal end; a swing arm rotatably coupled at a proximal
B64C 25/14 ( 2006.01 ) end to a distal end of the main fitting; a shock coupled at a
B64C 25/18 ( 2006.01 ) distal end to a distal end of the swing arm ; a bellcrank
(52) U.S. CI. coupled at a distal end to a proximal end of the shock , and
CPC B64C 25/10 (2013.01 ) ; B64C 25/12 coupled at a proximal end to the main fitting; and a wheel
(2013.01 ) ; B64C 25/14 (2013.01 ) ; B64C 25/18 coupled to the swing arm .
(2013.01 ) ; B64C 25/20 (2013.01 ) ; B64C 25/26
(2013.01) 10 Claims , 14 Drawing Sheets
130

1.18
142 122

141

136

112 116
134
130
114
100 128
-102

102

104
125
108
124

106
 US 11,530,031 B2
Page 2

( 56 ) References Cited GB 914582 1/1963

GB 931916 7/1963
U.S. PATENT DOCUMENTS GB 984775 3/1965
GB 1216732 12/1970
3,870,254 A 3/1975 Watts
4,199,119 A 4/1980 Masclet OTHER PUBLICATIONS
4,328,939 A 5/1982 Davies
5,100,083 A 3/1992 Large Allwein , et al ., U.S. Appl. No. 15 /703,416 , filed Sep. 13 , 2017 .
8,061,653 B2 11/2011 Chow
8,123,161 B1 2/2012 Collins International Preliminary Report on Patentability issued in PCT /
10,967,959 B2 4/2021 Allwein US2018 /044116 mailed by the International Bureau dated Mar. 26 ,
2009/0284025 A1 11/2009 Salcombe 2020 .
2013/0020436 A1 1/2013 Ducos International Search Report issued in PCT/US2018 /044116 mailed
2015/0041587 A1 2/2015 Schmidt by the International Bureau dated Nov. 13 , 2018 .
2015/0069178 Al 3/2015 Brown USPTO ; Non - Final Office Action issued in U.S. Appl. No. 15 /703,416
2016/0023750 A1 1/2016 Thompson dated Jul. 30 , 2020 .
2018/0037314 A1 2/2018 Wilson USPTO ; Notice of Allowance issued in U.S. Appl. No. 15 /703,416
2019/0077499 Al 3/2019 Allwein dated Dec. 9 , 2020 .
USPTO ; Notice of Allowance issued in U.S. Appl. No. 15 /703,416
FOREIGN PATENT DOCUMENTS dated May 19 , 2020 .
USPTO ; Restriction Requirement issued in U.S. Appl. No. 15 /703,416
FR 1246932 11/1960 dated Feb. 26 , 2020 .
GB 592591 9/1947 Written Opinion of the International Searching Authority issued in
GB 644147 10/1950 PCT /US2018 /044116 mailed by the International Bureau dated
GB 797105 6/1958 Nov. 13 , 2018
U.S. Patent Dec. 20 , 2022 Sheet 1 of 14 US 11,530,031 B2
138

118
142
122

140 132

141 01
136 128

112 116

134
130
114
126
102

104
125
124 108

106
FIG . 1
U.S. Patent Dec. 20 , 2022 Sheet 2 of 14 US 11,530,031 B2

118

|| ? 116

112

100

" 102

-108

FIG . 2
U.S. Patent Dec. 20 , 2022 Sheet 3 of 14 US 11,530,031 B2

110

118

116
100

114

102

104 108

106

FIG . 3
U.S. Patent Dec. 20 , 2022 Sheet 4 of 14 US 11,530,031 B2

INS
108

112
118

FIG . 4
U.S. Patent Dec. 20 , 2022 Sheet 5 of 14 US 11,530,031 B2

mwing e
VAWM
The

VOZ
.

114

ris, 152

w????? 150
100
2 .

102

FIG . 5
U.S. Patent Dec. 20 , 2022 Sheet 6 of 14 US 11,530,031 B2

FIG . 6

116

154
150
152
100

102
U.S. Patent Dec. 20 , 2022 Sheet 7 of 14 US 11,530,031 B2

118

116
O OKTC
112
100
114

102

104
108

FIG . 7
U.S. Patent Dec. 20 , 2022 Sheet 8 of 14 US 11,530,031 B2

118

112 110

114
122
102

108
100

106

FIG . 8
U.S. Patent Dec. 20 , 2022 Sheet 9 of 14 US 11,530,031 B2

112 102 108

106

114
100 104

118

FIG . 9
U.S. Patent Dec. 20 , 2022 Sheet 10 of 14 US 11,530,031 B2

108

110
102

114

116

D
118
tel
1 12

FIG . 10
U.S. Patent Dec. 20 , 2022 Sheet 11 of 14 US 11,530,031 B2

108

102 114

ID
106

112

118
110

FIG . 11
U.S. Patent Dec. 20 , 2022 Sheet 12 of 14 US 11,530,031 B2

108

D
116
102

FIG . 12
U.S. Patent Dec. 20 , 2022 Sheet 13 of 14 US 11,530,031 B2

112

ic 104

102 114
100

FIG . 13
U.S. Patent Dec. 20 , 2022 Sheet 14 of 14 US 11,530,031 B2

FIG . 14
118
1 1
.

1
1
2 4AWY

112 110
116
100
102

104

106
108
 US 11,530,031 B2
1 2
FOLDING TRAILING ARM LANDING GEAR a distal end to the bellcrank and configured to couple to a
wing at a proximal end, the drivelink being configured in an
This application is a divisional of U.S. application Ser . orientation off -parallel from the main fitting, and off -normal
No. 15 /703,416 , filed Sep. 13 , 2017 , for FOLDING TRAIL- from the main fitting.
ING ARM LANDING GEAR , which is incorporated in its 5 In a further embodiment, the invention may be charac
entirety herein by reference. terized as a folding trailing arm landing gear assembly
comprising a main fitting configured to couple to a hinge
BACKGROUND OF THE INVENTION positioned at a proximal end ; a swing arm rotatably coupled
at a proximal end to a distal end of the main fitting; a shock
1. Field of the Invention 10 coupled at a distal end to a distal end of the swing arm ; a
bellcrank coupled at a distal end to a proximal end of the
The present invention relates generally to a folding trail- shock , and coupled at a proximal end to the main fitting; a
ing arm landing gear assembly. wheel coupled to the swing arm ; a drivelink coupled at a
distal end to the bellcrank and configured to couple to a wing
2. Discussion of the Related Art 15 at a proximal end, the drivelink being configured in an
orientation off -parallel from the main fitting, and off-normal
Foldable retractable landing gear for aircraft has been one from the main fitting; and a lock solenoid coupled to the
of the significant advancements in aircraft engineering since main fitting and configured to lock the bellcrank into a
the dawn of powered aircraft flight. The ability to fold deployed position when locked , and configured to release
landing gear into the wing of an airplane or into the fuselage 20 the bellcrank when unlocked .
of an airplane reduces the drag profile of the airplane in In yet another embodiment, the invention may be char
flight, thereby enhancing handling characteristics, speed and acterized as a method of operating a folding trailing arm
efficiency. landing gear assembly comprising the steps of actuating a
One of the challenges, however, the designers face in lock solenoid to release a lock, wherein the lock secures a
aircraft with foldable retractable landing gear is the space 25 bellcrank in a deployed position ; actuating a retract servo to
needed within the aircraft for the landing gear. This is pull a main fitting toward aa side of the aircraft and rotate the
particularly true in those cases where aircraft volume is a main fitting; pulling a bellcrank away from the main fitting
principal design characteristic, such as when attempting to with a drivelink in response to the movement of the main
reduce aircraft volume so that the aircraft can be efficiently fitting; pulling a shock toward the bellcrank in response to
deployed on, for example, an aircraft carrier, where space is 30 the pulling of the bellcrank ; pulling a swing arm toward the
at a premium . bellcrank in response to the pulling of the shock .
Another instance where this challenge comes into play is BRIEF DESCRIPTION OF THE DRAWINGS
with smaller aircraft .
As such , improvements in the design of aircraft landing
gear that reduce the space needed within the aircraft for the 35 The above and other aspects , features and advantages of
landing gear, or, for example, reduce the length or depth of several embodiments of the present invention will be more
a well or compartment needed for the stowed landing gear, apparent from the following more particular description
are desirable. thereof, presented in conjunction with the following draw
At the same time , simpler designs are generally preferable ings .
to complex designs, and forcing shocks into compression in 40 FIG . 1 is a perspective view of a folding trailing arm
order to reduce stowed volume can introduce additional landing gear assembly in accordance with one embodiment
challenges. of the present invention .
As such , improvements are needed in the design of FIG . 2 is a front view of a folding trailing arm landing
foldable retractable landing gear for aircraft. gear assembly in accordance with the embodiment of the
45 present invention of FIG . 1 .
SUMMARY OF THE INVENTION FIG . 3 is a side view of a folding trailing arm landing gear
assembly in accordance with the embodiment of the present
Several embodiments of the invention provide a folding invention of FIG . 1 .
trailing arm landing gear assembly. FIG . 4 is a top view of a folding trailing arm landing gear
In one embodiment, the invention can be characterized as 50 assembly in accordance with the embodiment of the present
a folding trailing arm landing gear assembly comprising a invention of FIG . 1 .
main fitting configured to couple to a hinge positioned at a FIG . 5 is a side detailed view of a folding trailing arm
proximal end; a swing arm rotatably coupled at a proximal landing gear assembly in a locked position in accordance
end to aa distal end of the main fitting; a shock coupled at a with the embodiment of the present invention of FIG . 1 .
distal end to a distal end of the swing arm ; a bellcrank 55 FIG . 6 is a side detailed view of a folding trailing arm
coupled at a distal end to a proximal end of the shock , and landing gear assembly in an unlocked position in accordance
coupled at a proximal end to the main fitting; and a wheel with the embodiment of the present invention of FIG . 1 .
coupled to the swing arm . FIG . 7 is aa front perspective view of a folding trailing arm
In another embodiment, the invention can be character- landing gear assembly in a deployed position in accordance
ized as a folding trailing arm landing gear assembly com- 60 with the embodiment of the present invention of FIG . 1 .
prising a main fitting configured to couple to a hinge FIG . 8 is aa front perspective view of a folding trailing arm
positioned at a proximal end ; a swing arm rotatably coupled landing gear assembly in an intermediate position in accor
at a proximal end to a distal end of the main fitting; a shock dance with the embodiment of the present invention of FIG .
coupled at a distal end to a distal end of the swing arm ; a 1 .
bellcrank coupled at a distal end to a proximal end of the 65 FIG.9 is aa front perspective view of a folding trailing arm
shock , and coupled at a proximal end to the main fitting; a landing gear assembly in a folded position in accordance
wheel coupled to the swing arm ; and a drivelink coupled at with the embodiment of the present invention of FIG . 1 .
 US 11,530,031 B2
3 4
FIG . 10 is a top perspective view of a folding trailing armgear well or compartment ). The hinge 122 is aligned parallel
landing gear assembly in a folded position in accordance to the longitudinal axis (or roll axis ) of the aircraft, thereby
with the embodiment of the present invention of FIG . 1 . permitting rotation of the main fitting 100 on an axis parallel
FIG . 11 is a top view of a folding trailing arm landing gear
to the longitudinal axis of the aircraft. The main fitting 100
assembly in a folded position in accordance with the 5 is pivotally coupled at a distal end to a proximal end of the
embodiment of the present invention of FIG . 1 . swing arm 104. The swing arm 104 is coupled to the main
FIG . 12 is a side view of a folding trailing arm landing fitting 100 on a pivot pin 124 , thereby permitting rotation of
gear assembly in a folded position in accordance with the the swing arm 104 on an axis parallel to the lateral axis ( or
embodiment of the present invention of FIG . 1 . pitch axis) of the aircraft.
FIG . 13 is an end view of a folding trailing arm landing 10 The wheel - tire assembly 108 , and the brake assembly 106
gear assembly in a folded position in accordance with the are coupled to a distal end of the swing arm 104 trailing the
embodiment of the present invention of FIG . 1 . main fitting 100 in a conventional manner to allow rotation
FIG . 14 is a front perspective view of a folding trailing of the wheel - tire assembly 108 about an axis that is parallel
arm landing gear assembly in a deployed position shown in to the lateral axis ( or pitch axis ) of the aircraft.
combination with an aircraft wing in accordance with the 15 The shock 102 is pivotally coupled at a distal end of the
embodiment of the present invention of FIG . 1 . shock 102 to the distal end of the swing arm 104 near where
Corresponding reference characters indicate correspond- the wheel- tire assembly 108 is coupled to the distal end of
ing components throughout the several views of the draw- the swing arm 104 via a pivot pin 125 that permits rotation
ings . Skilled artisans will appreciate that elements in the about an axis parallel to the lateral axis ( or pitch axis ) of the
figures are illustrated for simplicity and clarity and have not 20 aircraft, and pivotally coupled at a proximal end of the shock
necessarily been drawn to scale . For example, the dimen- 102 to a distal end of the bellcrank 114 via a pivot pin 126
sions of some of the elements in the figures may be exag- that permits rotation about an axis parallel to the lateral axis
gerated relative to other elements to help to improve under- (or pitch axis) of the aircraft. A proximal end of the bellcrank
standing of various embodiments of the present invention . 114 is coupled to proximal end of the main fitting 100 near
Also , common but well-understood elements that are useful 25 the hinge 122 via a pivot pin 128 that permits rotation about
or necessary in a commercially feasible embodiment are the lateral axis (pitch axis) of the aircraft .
often not depicted in order to facilitate aa less obstructed view The bellcrank 114 transfers shock 102 load into main
of these various embodiments of the present invention . fitting 100 and aids in shrinking gear during retraction as
described herein further below .
DETAILED DESCRIPTION 30 The drivelink 116 is coupled to the bellcrank 114 at a
distal end of the drivelink 116 near the center of the
The following description is not to be taken in a limiting bellcrank 114 via aa first spherical bearing 130. ( A spherical
sense, but is made merely for the purpose of describing the bearing is a bearing that permits angular rotation about a
general principles of exemplary embodiments . The scope of central point in two orthogonal directions . ) And , the driv
the invention should be determined with reference to the 35 elink 116 is coupled to the aircraft at a proximal end via a
claims . second spherical bearing 132. As depicted, the second
Reference throughout this specification to “ one embodi- spherical bearing 132 is behind the hinge 122 , and to the
ment,” “ an embodiment, ” or similar language means that a right of the hinge 122 (when viewed from the front of the
particular feature, structure, or characteristic described in aircraft ), whereby the drivelink 116 exerts an upward force
connection with the embodiment is included in at least one 40 on the bellcrank 114 when the main fitting 100 is rotated at
embodiment of the present invention . Thus, appearances of the hinge 122 about the axis parallel to the longitudinal axis
the phrases “ in one embodiment,” “ in an embodiment, ” and ( roll axis ) in a direction to the left of the hinge 122 (when
similar language throughout this specification may , but do viewed from the front of the aircraft). The drivelink 116 is
not necessarily, all refer to the same embodiment. a two - force member that drives shrinking of the landing gear
Furthermore , the described features, structures, or char- 45 assembly during retraction .
acteristics of the invention may be combined in any suitable Note that these “ left” and “ right ” references are for
manner in one or more embodiments. purposes of explanation , as it is anticipated that in most
High performance aircraft by nature are volume chal- applications a mirror image landing gear would be employed
lenged for packaging landing gear assemblies. Minimizing on an opposite wing of the aircraft. As such , references to
landing gear retracted volume supports more efficient air- 50 “ left” and “ right " should be reversed in reference to this
frame structure , more efficient fuel volume , and greater mirror image landing gear.
provisions for a variety of mission payloads. This challenge The lower side brace 112 is pivotally coupled to the main
is amplified for carrier -based aircraft which experience high fitting 100 at a point down from the hinge 122 about
landing sink rates, require long landing gear for aircraft one - quarter to one - third of the way to the distal end of the
carrier operations aircraft clearances, and longs stroke to 55 main fitting 100 at a distal end of the lower side brace 112 .
lower impact loads . The lower side brace 112 is oriented normal to the longitu
Referring first to FIG . 1 , shown is a perspective view of dinal axis , and parallel to the lateral axis . The lower side
a folding trailing arm landing gear assembly for an aircraft brace 112 is pivotally coupled to the main fitting 100 via a
in accordance with one embodiment of the present inven- pivot pin 134 that permits rotation about an axis of rotation
tion . Shown is aa main fitting 100 , a shock 102 , a swing arm 60 that is substantially parallel to the axis of rotation of the
104 , a brake assembly 106 , a wheel -tire assembly 108 , an hinge 122 .
upper side brace 110 , a lower side brace 112 , a bellcrank 114 , The upper side brace 110 ( which forms part , i.e. , one leg,
9

a drivelink 116 , a retract servo 118 , and aa lock solenoid 150 . of a crank mechanism 138 ) is pivotally coupled at a distal
The main fitting 100 is pivotally coupled at a proximal end to the proximal end of the lower side brace 112 via a
end to an aircraft, such as below the wing of the aircraft, at 65 pivot pin 136 that permits rotation about an axis of rotation
a hinge 122 ( half of which is shown , another half of which that is substantially parallel to the axis of rotation of the
is affixed to the wing , such as below the wing in a landing hinge 122 .
 US 11,530,031 B2
5 6
The upper side brace 110 forms one leg of a crank nisms have not heretofore been used with a bellcrank 114
mechanism 138 , with its proximal end being fixed to the affixed to the landing gear strut (the main fitting 100 ) ,
wing of the aircraft at a pivot pin that permits the upper side rotating the wheel about the pivot pin 124 at the distal end
brace 110 to rotate about an axis that is substantially parallel of the swing arm 104 with no shock 102 compression.
to the axis of rotation of the hinge 122 , i.e. , substantially 5 Referring next to FIG . 2 , a front view is shown of a
parallel to the longitudinal axis of the aircraft. folding trailing arm landing gear assembly in accordance
The crank mechanism 138 includes a crank arm 140 with the embodiment of the present invention of FIG . 1 .
pivotally coupled via a pivot pin 141 to a distal end of a Shown is the main fitting 100 , the shock 102 , the swing
retract servo 118. A proximal end of the retract servo 118 is arm 104 , the brake assembly 106 , the wheel -tire assembly
coupled via a pivot pin 142 to the wing, such as in a landing 10 108 , the upper side brace 110 , the lower side brace 112 , the
gear well or compartment. bellcrank 114 , the drivelink 116 , the retract servo 118 , and
The retract servo 118 contracts from a deployed position , the lock solenoid 150 .
i.e. , from a fully expanded state , to pull the crank arm 140 , Referring next to FIG . 3 , a side view is shown of a folding
and thereby rotate the crank mechanism 138. When the trailing arm landing gear assembly in accordance with the
crank mechanism 138 rotates in this fashion , the upper side 15 embodiment of the present invention of FIG . 1 .
brace 110 rotates , and moves the distal end of the upper side Shown is the main fitting 100 , the shock 102 , the swing
brace 110 toward the main fitting 100 causing the lower side arm 104 , the brake assembly 106 , the wheel- tire assembly
brace 112 to pull the main fitting 100 to the side ( toward the 108 , the upper side brace 110 , the lower side brace 112
crank mechanism 138 , or to the left, when viewed from the ( obscured from view ) , the bellcrank 114 , the drivelink 116 ,
front of the aircraft) and up ( toward the wing, e.g. , into the 20 the retract servo 118 , and the lock solenoid 150 .
landing gear well or compartment ). Referring next to FIG . 4 , a top view is shown of a folding
The above combination provides a landing gear retract trailing arm landing gear assembly in accordance with the
mechanism that condenses a retracted gear volume to allow embodiment of the present invention of FIG . 1 .
more efficient aircraft integration of landing gear. Shown is the main fitting 100 , the shock 102 ( obscured
The drivelink 116 drives the bellcrank 114 attached to the 25 from view ) , the swing arm 104 ( obscured from view ), the
shock 102 that rotates the main gear swing arm 104 ( trailing brake assembly 106 , the wheel - tire assembly 108 , the upper
arm ) during retraction and deployment. The mechanism side brace 110 , the lower side brace 112 , the bellcrank 114 ,
requires no separate actuation ( other than to retract a servo the drivelink 116 , the retract servo 118 , and the lock solenoid
( lock solenoid 150 ) ) or high - load compression of the shock 150 .
102 . 30 FIG . 5 is aa detailed partial side view of a folding trailing
In operation, after the aircraft is airborne, pressure is arm landing gear assembly in a locked position in accor
applied to the brake assembly 106 to bring the wheel- tire dance with the embodiment of the present invention of FIG .
assembly 108 to est . Next, the lock solenoid 150 (or 1.
bellcrank 114 solenoid lock 152 ( described below ) ) is com- Shown is the main fitting 100 , the shock 102 , the bell
manded to open by energizing the lock solenoid 150. The 35 crank 114 , the drivelink 116 , and a lock solenoid 150 .
lock solenoid 150 serves as a fail - safe to prevent movement The shock 102 is pivotally coupled at a proximal end of
of the bellcrank 114 while the landing gear is deployed . the shock 102 to aa distal end of the bellcrank 114 via a pivot
Next, the retract servo 118 is energized and contracts to pin 126 that permits rotation about an axis parallel to the
retract the landing gear into a well or compartment in the lateral axis or pitch axis ) of the aircraft. A proximal end of
wing. To retract the landing gear, the distal end of the crank 40 the bellcrank 114 is coupled to proximal end of the main
arm 140 of the crank mechanism 138 rotates toward the fitting 100 via a pivot pin that permits rotation about the
main fitting 100. This rotation causes the distal end of the lateral axis (pitch axis ) of the aircraft .
upper side arm to rotate toward the main fitting 100. In The bellcrank 114 transfers shock 102 load into main
response , the lower side arm pulls the main fitting 100 fitting 100 and aids in shrinking gear during retraction as
toward the crank mechanism 138 and wing. As the main 45 described herein further below .
fitting 100 rotates toward the crank mechanism 138 , the The drivelink 116 is coupled to the bellcrank 114 at a
drive link pulls the bellcrank 114 away from the main fitting distal end of the drivelink 116 near the center of the
100. The bell crank pulls up on the shock 102 , which pulls bellcrank 114 via a first spherical bearing 130. The drivelink
up on the swing arm 104 , and wheel - tire assembly 108 ,
2 116 is a two - force member that drives shrinking of the
moving the wheel - tire assembly 108 toward the hinge 122. 50 landing gear assembly during retraction .
As the retract servo 118 continues to pull the crank arm The drivelink 116 drives the bellcrank 114 attached to the
140 toward the main fitting 100 , the upper side arm finally shock 102 that rotates the main gear swing arm 104 ( trailing
assumes an orientation roughly parallel to the main fitting arm ) during retraction and deployment. The mechanism
100 , and thereby pulls the landing gear into its retracted requires no separate actuation ( other than to retract a servo
position, such as in the well , or the compartment. 55 (lock solenoid 150 ) ) or high -load compression of the shock
The present embodiment of the invention utilizes an 102 .
existing degree of freedom at the pivot pin at the proximal In operation, the lock solenoid 150 (or bellcrank 114
end of the swing arm 104 , to optimize the retracted shape of solenoid lock 152 ( shown in the locked position )) is com
the landing gear. The bellcrank 114 causes the swing arm manded to open (as shown in FIG . 6 ) by energizing the lock
104 rotation . 60 solenoid 150. The lock solenoid 150 serves as a fail -safe to
Separating a strut into two components , a traditional strut prevent movement of the bellcrank 114 while the landing
( the main fitting 100 ) and a secondary bellcrank 114 ( the gear is deployed.
bellcrank 114 ) permits movement without shock 102 com- As the main fitting 100 rotates toward the crank mecha
pression or secondary actuators, which would otherwise lead nism 138 , the drive link pulls the bellcrank 114 away from
to lower reliability and greater weight. 65 the main fitting 100 (this movement has begun in the
The bellcrank 114 is driven by a slaved mechanism fixed illustration of FIG . 6 ) . The bell crank pulls up on the shock
to the airframe, i.e. , the drivelink 116. Similar slaved mecha- 102 .
 US 11,530,031 B2
7 8
The lock solenoid 150 operates a lock 152 that ensures FIG . 10 is a top perspective view of a folding trailing arm
that the shock 102 and bell crank remain over center when landing gear assembly in a folded position in accordance
the landing gear is down and locked . with the embodiment of the present invention of FIG . 1 .
Sudden extension loads are reacted by the lock 152 , Shown is the main fitting 100 , the shock 102 , the swing
preventing movement of the bellcrank 114 until the lock 1525 arm 104 , the brake assembly 106 , the wheel -tire assembly
9

is operated by the lock solenoid 150. The lock 152 must be 108 , the upper side brace 110 , the lower side brace 112 , the
retracted ( as shown in FIG . 6 ) prior to gear retraction . bellcrank 114 , the drivelink 116 , the retract servo 118 , and
The lock 152 incorporates a ramp profile 154 on an aft the lock solenoid 150 .
face for passive locking of the bell crank during deployment 10 FIG . 11 is a top view of a folding trailing arm landing gear
of the landing gear. assembly in a folded position in accordance with the
FIG . 6 is a side detailed view of a folding trailing arm embodiment of the present invention of FIG . 1 .
landing gear assembly in an unlocked position in accordance Shown is the main fitting 100 , the shock 102 , the swing
with the embodiment of the present invention of FIG . 1 . arm 104 , the brake assembly 106 , the wheel -tire assembly
108 , the upper side brace 110 , the lower side brace 112 , the
Shown is the main fitting 100, the shock 102 , the bell- 15 bellcrank 114, the drivelink 116, the retract servo 118, and
crank 114 , the drivelink 116 , and a lock solenoid 150 . the lock solenoid 150 .
FIG . 7 is a front perspective view of a folding trailing arm
a FIG . 12 is a side view of aa folding trailing arm landing
landing gear assembly in a deployed position in accordance gear assembly in a folded position in accordance with the
with the embodiment of the present invention of FIG . 1 . embodiment of the present invention of FIG . 1 .
Shown is the main fitting 100 , the shock 102 , the swing 20 Shown is the main fitting 100 , the shock 102 , the swing
arm 104 , the brake assembly 106 , the wheel -tire assembly arm 104 , the brake assembly 106 , the wheel -tire assembly
108 , the upper side brace 110 , the lower side brace 112 , the 108 , the upper side brace 110 , the lower side brace 112 , the
9

bellcrank 114 , the drivelink 116 , the retract servo 118 , and bellcrank 114 , the drivelink 116 , the retract servo 118 , and
the lock solenoid 150 . the lock solenoid 150 .
In operation, after the aircraft is airborne, pressure is 25 FIG . 13 is an end view of a folding trailing arm landing
applied to the brake assembly 106 to bring the wheel - tire gear assembly in a folded position in accordance with the
assembly 108 to rest . Next, the lock solenoid 150 (or embodiment of the present invention of FIG . 1 .
bellcrank 114 solenoid lock 152 ( described below ) ) is com Shown is the main fitting 100 , the shock 102 , the swing
manded to open by energizing the lock solenoid 150. The arm 104 , the brake assembly 106 , the wheel- tire assembly
lock solenoid 150 serves as a fail-safe to prevent movement 30 108 , the upper side brace 110, the lower side brace 112, the
bellcrank 114 , the drivelink 116 , the retract servo 118 , and
of the bellcrank 114 while the landing gear is deployed.
FIG . 8 is a front perspective view of a folding trailing arm theFIG
lock solenoid 150 .
. 14 is a front perspective view of a folding trailing
landing gear assembly in an intermediate position in accor arm landing gear assembly in a deployed position shown in
dance
1.
with the embodiment of the present invention of FIG . 35 combination with an aircraft wing in accordance with the
Shown is the main fitting 100 , the shock 102 , the swing embodiment of the present invention of FIG . 1 .
arm 104 , the brake assembly 106 , the wheel - tire assembly Shown is the main fitting 100 , the shock 102 , the swing
2 arm 104 , the brake assembly 106 , the wheel - tire assembly
108 , the upper side brace 110 , the lower side brace 112 , the 108 , the upper side brace 110 , the lower side brace 112 , the
bellcrank 114 , the drivelink 116 , the retract servo 118 , and 40 bellcrank 114 , the drivelink 116 , the retract servo 118 , and
the lock solenoid 150 . the lock solenoid 150. Also shown is the aircraft wing .
The retract servo 118 is energized and contracts to retract While the invention herein disclosed has been described
the landing gear into aa well or compartment in the wing . To by means of specific embodiments, examples and applica
retract the landing gear, the distal end of the crank arm 140 tions thereof, numerous modifications and variations could
of the crank mechanism 138 rotates toward the main fitting 45 be made thereto by those skilled in the art without departing
100. This rotation causes the distal end of the upper side arm from the scope of the invention set forth in the claims .
to rotate toward the main fitting 100. In response, the lower What is claimed is :
side arm pulls the main fitting 100 toward the crank mecha- 1. A method of operating a folding trailing arm landing
nism 138 and wing . As the main fitting 100 rotates toward gear assembly for an aircraft comprising steps of:
the crank mechanism 138 , the drive link pulls the bellcrank
2 50 actuating a lock solenoid to release a lock , wherein the
114 away from the main fitting 100. The bell crank pulls up lock secures a bellcrank in a deployed position ;
on the shock 102 , which pulls up on the swing arm 104 , and actuating a retract servo to pull a main fitting toward a
wheel - tire assembly 108 , moving the wheel -tire assembly side of the aircraft and rotate the main fitting;
108 toward the hinge 122 . pulling the bellcrank away from the main fitting with a
FIG . 9 is aa front perspective view of a folding trailing arm 55 drivelink in response to movement of the main fitting;
landing gear assembly in a folded position in accordance pulling a shock toward the bellcrank in response to the
with the embodiment of the present invention of FIG . 1 . pulling of the bellcrank ;
Shown is the main fitting 100 , the shock 102 , the swing pulling a swing arm toward the bellcrank in response to
arm 104 , the brake assembly 106 , the wheel - tire assembly the pulling of the shock .
108 , the upper side brace 110 , the lower side brace 112 , the 60 2. The method of operating the folding trailing arm
bellcrank 114 , the drivelink 116 , the retract servo 118 , and landing gear assembly of claim 1 further comprising:
the lock solenoid 150 . rotating a crank mechanism in response to the actuating of
As the retract servo 118 continues to pull the crank arm the retract servo .
140 toward the main fitting 100 , the upper side arm finally 3. The method of operating the folding trailing arm
assumes an orientation roughly parallel to the main fitting 65 landing gear assembly of claim 1 further comprising:
100 , and thereby pulls the landing gear into its retracted actuating the retract servo to push the main fitting toward
position , such as in the well , or the compartment. the deployed position ;
 US 11,530,031 B2
9 10
pushing the bellcrank toward the main fitting with the said main fitting in a direction away from the drivelink,
drivelink in response to the movement of the main wherein the drivelink pulls the bellcrank when the retract
fitting; servo pulls the main fitting.
pushing the shock toward the bellcrank in response to 8. The method of operating the folding trailing arm
pushing the bellcrank ; 5 landing gear assembly of claim 7 said actuating of said
pushing the swing arm away from the bellcrank in retract servo to pull said main fitting toward a side of the
response to the pushing of the shock ; aircraft and rotate said main fitting further comprises actu
locking the bellcrank into the deployed position . ating said retract servo to pull a crank mechanism that pulls
4. The method of operating the folding trailing arm said
landing gear assembly of claim 3 wherein said locking 10 9. main fitting.
comprises locking the bellcrank into the deployed position landing gearmethod
The
assembly
of operating the folding trailing arm
of claim 7 wherein said actuating of
without actuating the lock solenoid . said retract servo to pull said main fitting toward aa side of the
5. The method of operating the folding trailing arm aircraft and rotate said main fitting further comprises actu
landing gear assembly of claim 1 further comprising:
moving the folding trailing arm landing gear assembly 15 ating said retract servo to pull a crank mechanism that pulls
into a well in response to the actuating of the retract a lower side brace that pulls said main fitting.
10. The method of operating the folding trailing arm
servo .
6. The method of operating the folding trailing arm landing gear assembly of claim 1 wherein said pulling said
landing gear assembly of claim 1 wherein said pulling of a bellcrank away from said main fitting with said drivelink in
trailing arm toward said bellcrank is without compressing 20 response
pulling saidto bellcrank
the movement of the main
into a retracted fitting
position includes
wherein said
the shock .
7. The method of operating the folding trailing arm bellcrank pulls said shock wherein the shock pulls the swing
landing gear assembly of claim 1 wherein said actuating of arm whereby a distance between a hinge on which said main
said retract servo to pull said main fitting toward a side of the fitting rotates and a wheel -tire assembly is reduced .
aircraft and rotate said main fitting further comprises pulling