US4594945A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal protection for propellant grains
Assignee: Raytheon Co
•
Filing: 1984-11-28
•
Granted: 1986-06-17
•
Expires: 2004-11-28
Abstract
Abstract A thin frangible cork barrier conforming to the contour of the burning surface of individual solid propellant grains in a multiple grain rocket motor prevents premature ignition of the protected grain by the heat of combustion of previously ignited adjacent grains and is expelled through the rocket motor nozzle upon ignition of the protected grain. In a second embodiment, the thermal protection afforded by the frangible cork barrier is augmented by bonding to a thermally-protective elastomer layer which is in turn bonded to the propellant grain burning surface. By virtue of the composition and structure of the embodiments, thermal protection is afforded. Upon ignition of a protected grain the thermal barrier breaks up so as to pass readily through the throat of a small motor nozzle.
Inventors
- 👤 George Alexandris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 04:59
CPC Classifications
F; F02; F02K; F02K9/00; F02K9/08; F02K9/10; F02K9/12; C; C06; C06B; C06B45/00; C06B45/12; F02K9/32; F02K9/34; F02K9/346
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
106 words
Thermal protection for use with a protected grain of a multiple grain solid propellant rocket motor having a single combustion chamber and thrust nozzle, comprising: a flexible frangible barrier layer of pressed granular material held together by a binder material and bondable over the combustion surface of the protected grain said layer comprising means for preventing ingition of said combustion surface by the burning of an adjacent propellant grain and means for fracturing into small pieces to be propelled out through the thrust nozzle on ignition of the protected grain, and means for bonding said barrier layer over the entire area of said protected grain surface.
Claim 2
Dependent Claim
106 words
Thermal protection for use with a protected grain of a multiple grain solid propellant rocket motor having a single combustion chamber and thrust nozzle, comprising: a flexible frangible barrier layer of pressed granular material held together by a binder material and bondable over the combustion surface of the protected grain said layer comprising means for preventing ingition of said combustion surface by the burning of an adjacent propellant grain and means for fracturing into small pieces to be propelled out through the thrust nozzle on ignition of the protected grain, and means for bonding said barrier layer over the entire area of said protected grain surface.
Claim 3
Dependent Claim
70 words
Thermal protection for use with a protected grain of a multiple grain solid propellant rocket motor as recited in claim 1, wherein: said barrier is formed of a layer of material having a maximum density of between 28 to 32 pounds per cubic foot, a maximum tensile strength of 250 pounds per square inch, and a minimum specific hear value of 0.45 British Thermal Units per pound per degree Fahrenheit.
Claim 4
Dependent Claim
37 words
Thermal protection for use with a protected grain of a multiple grain solid propellant rocket motor as recited in claim 1, wherein: said barrier comprises a layer of pressed granular cork held together by a binder material.
Claim 5
Dependent Claim
33 words
Thermal protection for use with a protected grain of a multiple grain solid propellant rocket motor as recited in claim 3, wherein: said cork layer has a maximum thickness of one quarter inch.
Claim 6
Dependent Claim
42 words
Thermal protection for use with a protected grain of a multiple grain solid propellant rocket motor as recited in claim 1 wherein said bonding means includes a thermally resistant elastomer layer bonded between said protected grain combustion surface and said frangible barrier.
Claim 7
Dependent Claim
51 words
Thermal protection for use with a protected grain of a multiple grain solid propellant rocket motor as recited in claim 5 wherein: said elastomer layer thickness does not exceed 0.030 inch, and the combined thickness of said elastomer layer and said frangible barrier does not exceed three eighths of an inch.
Claim 8
Dependent Claim
145 words
A rocket motor comprising: a housing defining a combustion chamber having an exhaust nozzle at one end and a reduced diameter throat connecting the exhaust nozzle to the combustion chamber; a series of at least two propellant grains in the combustion chamber for independent and sequential ignition; a flexible frangible barrier layer bonded to cover the combustion surface of at least one of the propellant grains the barrier layer comprising a layer of pressed granular cork held together by a binder material and a bonding layer bonding the cork layer over the entire exposed combustion surface of the propellant grain, and the barrier layer comprising means for preventing ignition of said combustion surface by the burning of an adjacent propellant grain and means for fracturing into small enough pieces for ejection through the reduced diameter nozzle on ignition of the underlying propellant grain combustion surface.
Claim 9
Dependent Claim
145 words
A rocket motor comprising: a housing defining a combustion chamber having an exhaust nozzle at one end and a reduced diameter throat connecting the exhaust nozzle to the combustion chamber; a series of at least two propellant grains in the combustion chamber for independent and sequential ignition; a flexible frangible barrier layer bonded to cover the combustion surface of at least one of the propellant grains the barrier layer comprising a layer of pressed granular cork held together by a binder material and a bonding layer bonding the cork layer over the entire exposed combustion surface of the propellant grain, and the barrier layer comprising means for preventing ignition of said combustion surface by the burning of an adjacent propellant grain and means for fracturing into small enough pieces for ejection through the reduced diameter nozzle on ignition of the underlying propellant grain combustion surface.
Claim 10
Dependent Claim
43 words
The rocket motor as claimed in claim 7, wherein there are three propellant grains and each of the two innermost grains has a barrier layer bonded to its combustion surface at least one of the protected grains being of the radial burning type.
References Cited (Backward Citations)
US1335785A
Cited
US1840479A
Cited
US2078240A
Cited
US2211737A
Cited
US2357068A
Cited
US2398297A
Cited
US2643611A
Cited
US3172255A
Cited
US3965676A
Cited
US3157127A
Cited
US3430445A
Cited
US3324795A
Cited
US3263613A
Cited
US3991565A
Cited
US3609977A
Cited
US3815506A
Cited
US4054029A
Cited
US4085584A
Cited
US4458483A
Cited
US4478151A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-06-16 | 1989-12-16 | 1990-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-06-16 | 1993-12-16 | 1994-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-06-16 | 1997-12-16 | 1998-06-17 | $7700.00 | Window Closed / Lapsed |