US3716208A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Energy absorbing landing gear
Assignee: Bell Helicopter Textron Inc
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Filing: 1970-06-11
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Granted: 1973-02-13
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Expires: 1990-06-11
Abstract
Abstract A landing gear for helicopters in which a member having a static spring rate and plastic yielding characteristics is mounted in series with a member having a static spring rate and a velocitysensitive restraining force. The combination serves to provide for appropriately ''''soft'''' landings under conditions of light gross weight and/or low vertical descent speed, and is also capable of absorbing the forces generated during ''''hard'''' or crash landings under conditions of heavy gross weight and/or high vertical descent speed. By designing the yield point of the plastic yielding member to a force approximately equal to the resistance offered by the velocity-sensitive unit at the time that is ''''bottoms out,'''' the efficient energy absorbing properties of the plastically yielding member are employed to extend the energy absorbing capabilities of the gear.
Inventors
- 👤 C Fagan
- 👤 R Lynn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:34
CPC Classifications
B; B64; B64C; B64C25/00; B64C25/32; B64C25/52; B64C2025/325
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
74 words
An energy absorbing landing gear for an aircraft comprising: a landing skid; an elongated tubular spring member with one end connected to the aircraft; crank means with one end rotatably attached to said landing skid and the other end of the crank means rotatably attached to the other end of said tubular spring; and a liquid spring with one end rotatably connected to said crank and the other end rotatably connected to said skid.
Claim 2
Dependent Claim
74 words
An energy absorbing landing gear for an aircraft comprising: a landing skid; an elongated tubular spring member with one end connected to the aircraft; crank means with one end rotatably attached to said landing skid and the other end of the crank means rotatably attached to the other end of said tubular spring; and a liquid spring with one end rotatably connected to said crank and the other end rotatably connected to said skid.
Claim 3
Dependent Claim
74 words
An energy absorbing landing gear for an aircraft comprising: a landing skid; an elongated tubular spring member with one end connected to the aircraft; crank means with one end rotatably attached to said landing skid and the other end of the crank means rotatably attached to the other end of said tubular spring; and a liquid spring with one end rotatably connected to said crank and the other end rotatably connected to said skid.
Claim 4
Dependent Claim
74 words
An energy absorbing landing gear for an aircraft comprising: a landing skid; an elongated tubular spring member with one end connected to the aircraft; crank means with one end rotatably attached to said landing skid and the other end of the crank means rotatably attached to the other end of said tubular spring; and a liquid spring with one end rotatably connected to said crank and the other end rotatably connected to said skid.
Claim 5
Dependent Claim
45 words
An energy absorbing landing gear as defined in claim 1 wherein: said tubular spring member deflects upon the application of normal loads and deforms plastically upon the application of excessive loads; and said liquid spring member provides velocity sensitive resistance to the application of loads.
Claim 6
Dependent Claim
84 words
An energy absorbing landing gear for an aircraft comprising: a landing skid; an elongated tubular spring member with one end connected to the aircraft; crank means rotatably attached to the other end of said tubular spring; and a liquid spring with one end rotatably connected to said crank and the other end rotatably connected to said skid, said crank means being rotatably connected to said skid at a point on said crank between the points said tubular and liquid springs connect to said crank.
Claim 7
Dependent Claim
84 words
An energy absorbing landing gear for an aircraft comprising: a landing skid; an elongated tubular spring member with one end connected to the aircraft; crank means rotatably attached to the other end of said tubular spring; and a liquid spring with one end rotatably connected to said crank and the other end rotatably connected to said skid, said crank means being rotatably connected to said skid at a point on said crank between the points said tubular and liquid springs connect to said crank.
Claim 8
Dependent Claim
45 words
An energy absorbing landing gear as defined in claim 3 wherein: said tubular spring member deflects upon the application of normal loads and deforms plastically upon the application of excessive loads; and said liquid spring member provides velocity sensitive resistance to the application of loads.
Claim 9
Dependent Claim
91 words
An energy absorbing landing gear for an aircraft comprising: a landing skid; a pair of tubular springs with one end connected to the aircraft; a pair of crank means with a first end of each crank means rotatably attached to one of each of the other ends of said tubular springs and a second end of each crank means rotatably attached to said landing skid; and a pair of liquid springs each with one end rotatably connected to one of said cranks and the other end rotatably connected to said skid.
Claim 10
Dependent Claim
91 words
An energy absorbing landing gear for an aircraft comprising: a landing skid; a pair of tubular springs with one end connected to the aircraft; a pair of crank means with a first end of each crank means rotatably attached to one of each of the other ends of said tubular springs and a second end of each crank means rotatably attached to said landing skid; and a pair of liquid springs each with one end rotatably connected to one of said cranks and the other end rotatably connected to said skid.
Claim 11
Dependent Claim
48 words
The energy absorbing landing gear according to claim 5 wherein the liquid springs bottom upon the application of a predetermined load between the landing skid and the aircraft and wherein the tubular springs begin to collapse in plastic deformation upon the application of substantially the same predetermined load.
Claim 12
Dependent Claim
118 words
An energy absorbing landing gear for an aircraft comprising: a landing skid; a pair of tubular springs with one end connected to the aircraft; a pair of crank means with a first end of each of said crank means rotatably attached to oNe of each of the other ends of said tubular springs and a second end of each crank means rotatably attached to said landing skid; a pair of liquid springs each with one end rotatably connected to one of said cranks and the other end rotatably connected to said skid, said crank means being connected to said skids at a point on said crank between the points said tubular and liquid springs connect to said crank.
Claim 13
Dependent Claim
118 words
An energy absorbing landing gear for an aircraft comprising: a landing skid; a pair of tubular springs with one end connected to the aircraft; a pair of crank means with a first end of each of said crank means rotatably attached to oNe of each of the other ends of said tubular springs and a second end of each crank means rotatably attached to said landing skid; a pair of liquid springs each with one end rotatably connected to one of said cranks and the other end rotatably connected to said skid, said crank means being connected to said skids at a point on said crank between the points said tubular and liquid springs connect to said crank.
Claim 14
Dependent Claim
48 words
The energy absorbing landing gear according to claim 7 wherein the liquid springs bottom upon the application of a predetermined load between the landing skid and the aircraft and wherein the tubular springs begin to collapse in plastic deformation upon the application of substantially the same predetermined load.
Claim 15
Dependent Claim
86 words
An energy absorbing landing gear for an aircraft as defined in claim 7 wherein: said tubular and liquid springs are adapted whereby said springs are cooperable in a first low load range to linearly deflect with load, said springs operable in a second higher load range wherein said first spring is fully deflected whereby said second liquid spring absorbs substantially all energy, and operable at a third highest load range beyond the range of said liquid spring wherein said first spring plastically deforms to absorb energy.
Claim 16
Dependent Claim
53 words
An energy absorbing landing gear for an aircraft as defined in claim 7 wherein: said pair of tubular springs are located at forward and rear positions of the aircraft with said forward tubular spring being mounted for rotation relative to the aircraft and said rear tubular spring is fixed relative to the aircraft.
Claim 17
Dependent Claim
56 words
The energy absorbing landing gear according to claim 1 wherein the movement of the liquid spring member is limited by a stop, wherein the liquid spring member engages the stop upon the application of a predetermined load, and wherein the tubular spring member begins to plastically deform upon the application of substantially the same predetermined load.
Claim 18
Dependent Claim
36 words
The energy absorbing landing gear according to claim 1 wherein the tubular spring member is connected to one point on said crank and wherein the liquid spring member is connected to another point on said crank.
Claim 19
Dependent Claim
26 words
The energy absorbing landing gear according to claim 1 wherein the liquid spring shock functions both as a load dependent spring and as a viscous damper.
Claim 20
Dependent Claim
86 words
An energy absorbing landing gear for an aircraft as defined in claim 5 wherein: said tubular and liquid springs are adapted whereby said springs are cooperable in a first low load range to linearly deflect with load, said springs operable in a second higher load range wherein said first spring is fully deflected whereby said second liquid spring absorbs substantially all energy, and operable at a third highest load range beyond the range of said liquid spring wherein said first spring plastically deforms to absorb energy.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-13 | 1976-08-14 | 1977-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-13 | 1980-08-14 | 1981-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-13 | 1984-08-14 | 1985-02-13 | $7700.00 | Window Closed / Lapsed |