WO1999010237A2 - System and method for increasing the durability of a sapphire window in high stress environments - Google Patents
System and method for increasing the durability of a sapphire window in high stress environments Download PDFInfo
- Publication number
- WO1999010237A2 WO1999010237A2 PCT/US1998/017072 US9817072W WO9910237A2 WO 1999010237 A2 WO1999010237 A2 WO 1999010237A2 US 9817072 W US9817072 W US 9817072W WO 9910237 A2 WO9910237 A2 WO 9910237A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- plane
- planes
- dome
- missile
- positive
- Prior art date
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64G—COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
- B64G1/00—Cosmonautic vehicles
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
- F42B10/00—Means for influencing, e.g. improving, the aerodynamic properties of projectiles or missiles; Arrangements on projectiles or missiles for stabilising, steering, range-reducing, range-increasing or fall-retarding
- F42B10/32—Range-reducing or range-increasing arrangements; Fall-retarding means
- F42B10/38—Range-increasing arrangements
- F42B10/42—Streamlined projectiles
- F42B10/46—Streamlined nose cones; Windshields; Radomes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64G—COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
- B64G1/00—Cosmonautic vehicles
- B64G1/22—Parts of, or equipment specially adapted for fitting in or to, cosmonautic vehicles
- B64G1/24—Guiding or controlling apparatus, e.g. for attitude control
- B64G1/36—Guiding or controlling apparatus, e.g. for attitude control using sensors, e.g. sun-sensors, horizon sensors
Definitions
- This application claims priority from provisional application No. 60/ 030,520, docket No. PD-960429, filed November 12, 1996.
- This invention relates to missile systems. Specifically, the present invention relates to methods for preventing sapphire sensor housings and windows from cracking during missile flight.
- Advanced missile systems are used in a variety of applications ranging from explosives delivery to satellite launching. Such applications typically have stringent performance requirements. Missile sensing and tracking capability are important features affecting missile performance.
- a missile may be equipped with a combination of infrared, radar, and optical sensors for missile guidance i.e., terminal homing.
- the sensors and accompanying sensor housings are often exposed to extreme heat loads. Sensor damage, and signal blockage often result. This is particularly true for infrared (IR) sensors.
- IR infrared
- an IR sensor is encased in a sapphire housing called an IR dome.
- an IR dome will create a strong bow shock that results in a large pressure gradient and corresponding temperature heat load. This heating may crack the IR dome. Any resulting fracturing of the IR dome due to local heating may reduce missile performance.
- the system includes a pressurized " canister of argon stored in the missile body.
- the heat load on the IR dome becomes large, cold gas is released from the canister through a nozzle just forward of the IR dome.
- the cold argon gas has a different refractive index than air and bends signals entering the IR dome resulting in missile tracking errors.
- the canisters are bulky. The excess weight reduces the range of the missile and space constraints due to the canister increase the complexity and price of the missile system.
- the inventive assembly is adapted for use with a missile having a longitudinal axis parallel to a thrust vector thereof.
- the assembly includes a single crystal dome or window with a crystallographic structure having plural beveled facets.
- a surface around a missile sensor provides a place for mounting the crystal such that it can be oriented in a clocking manner to minimize the resolved shear stresses on those facets which correspond to crystallographic r-planes.
- the dome or window is mounted on the side of a missile and the crystal is sapphire and has a, c, r and n-planes.
- a positive direction of a c-plane normal vector is approximately perpendicular to the base of the infrared dome and points outward from the missile towards and through the center of the dome or window.
- a positive r-plane normal is defined to be one in which the projected component of that r-plane normal onto the c-plane normal vector is in the direction of the positive c-plane normal.
- an r-plane is approximately bisected by a plane formed by a wind flow vector and a crystallographic c-axis.
- the positive normal to this r-plane has a component that faces aft.
- the inventive system is adapted for use with infrared missile sensor domes and includes an x-ray device for locating the r-planes planes within the sensor dome.
- a turntable orients the sensor dome to the preferred orientation in which the first r-plane normal is rotated to the leeward direction.
- the projection of an r-plane normal of the second r-plane onto the c-plane forms an angle of approximately 60 degrees with respect to impinging airflow when projected to the same plane.
- the turntable includes a motor for strategically orienting the lattice planes of the dome so as to maximize the strength of the dome with respect to applied stresses.
- Fig. la is an isometric view of a sapphire crystal showing the relative orientation of lattice planes.
- Fig. lb is a top view of the sapphire crystal of Fig. la.
- Fig. 2 is an illustrative diagram showing the orientation of lattice planes of a sapphire crystal with respect to missile direction and air flow for a sapphire dome according to the teachings of the present invention.
- Fig. 3 is a top view of an IR dome machined and oriented so that its lattice plane orientation corresponds to the lattice plane orientation of the sapphire crystal of Fig. 2.
- Fig. la is an isometric view of a typical sapphire crystal 10 showing the relative orientation of n-planes 12, r-planes 14, a c-plane 16 and a-planes 18.
- the crystal 10 is grown and then machined to the desired shape. Typically, the crystal 10 is scooped from a large cylindrical boule using specialized machinery. The resulting near net shaped dome (not shown) is then ground and polished to its final dimensions. The finished dome (see Fig. 3), although smooth, still has a crystallographic structure as represented by the crystal 10.
- " Figures la, lb, and 2 represent only the orientation and directions of the crystallographic planes within the final sapphire product.
- Planes (not shown) parallel to the planes 14, 16, 18 are defined to be the same planes 14, 16, 18 respectively.
- the primary mode of dome fracture and failure at the high temperatures experienced during missile flight is due to shear stress resolved along on one or more of the crystallographic r-planes 14 throughout the machined dome or window (not shown).
- the r-planes 14, n-planes 12, and the c-plane 16 of the crystal 10 have normal vectors termed r-plane normals 20, n-plane normals 22 and the c-plane normal 24 respectively.
- the c-plane normals 24 are angled approximately 57.6 degrees with respect to the r-plane normals 20 and approximately 61 degrees with respect to the n- plane normals 22.
- the r-plane normals 20 are angled with respect to an m-axis (denoted (m)) represented by a vector 26 by approximately 32.4 degrees.
- the m-axis 26 is perpendicular to the c-plane normal 24.
- the c-plane normal 24 is normal to the c-plane 16 and corresponds to a c-axis 24.
- the positive direction of the c-plane normal 24 is defined to be in the direction from the infrared sensor (not shown) internal to the missile (see Fig. 3) and perpendicular to the c-plane 16 toward and through the center of the dome or window (see Fig. 3) to the exterior environment.
- a positive r-plane normal 20 is defined to be one in which the projected component of that r-plane normal onto the c-plane normal vector 24 is in the direction " of the positive c-plane normal 24.
- Fig. lb is a top view of the sapphire crystal 10 of Fig. la.
- Fig. lb represents the crystalline structure of a typical IR dome (not shown). This view is from the positive c-axis (see 24 of Fig. la) looking in the direction of the negative c-axis.
- IR infrared
- domes are machined and placed on missiles without regard to the structural orientation of the crystal 10 except for the orientation of the c- axis.
- Fig. 2 is an illustrative diagram showing the orientation of lattice planes of a sapphire crystal piece 30 with respect to a missile 32 direction and air flow for a sapphire dome (not shown) according to the teachings of the present invention.
- a vector 34 which points opposite to the direction of wind flow 36 is parallel to the c- plane 16.
- the vector 34 forms an angle of approximately 60 degrees with the projection of the positive r-plane normal 38 onto the c-plane 16. Shear stresses (not shown) resolved along the r- planes 14 are reduced.
- the positive normal to the r-plane 14 points aft.
- the negative r-plane normal intersects the nominal wind flow vector 36.
- the wind flow vector 36 is aligned with the longitudinal missile axis 42 for a nominal no-yaw, no-pitch flight.
- the longitudinal axis 42 is parallel to a thrust vector 40.
- Fig. 3 is a diagram of an infrared (IR) dome 50 machined and oriented so that its lattice plane orientation corresponds to the lattice plane orientation of the sapphire crystal of Fig. 2.
- the dome 50 is cut and machined from a single large sapphire crystal.
- the dome 50 has the same structural orientation with respect to the crystal lattice planes, i.e., the a-planes, r-planes, n-planes, and the c-plane as the schematic crystal 30 of Fig. 2.
- the projection of the r-plane normal 38 onto the c- plane forms approximately a 60 degree angle with respect to the impinging airflow vector (see 36 of Fig. 2).
- the IR dome 50 is mounted on a turntable (not shown).
- the turntable includes a motor (not shown) for orienting the lattice planes of the IR dome so as to - maximize the strength of the IR dome with respect to applied stresses.
- the method according to the teachings of the present invention comprises the steps of:
- An alternative method according to the teachings of the present invention comprises the steps of:
- a second alternative method according to the teachings of the present invention comprises the steps of: 1. obtaining prefabricated single crystal sapphire IR dome,
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11514374A JP2001502045A (en) | 1997-08-19 | 1998-08-17 | Systems and methods for increasing the durability of sapphire windows in high stress environments |
CA002267562A CA2267562A1 (en) | 1997-08-19 | 1998-08-17 | System and method for increasing the durability of a sapphire window in high stress environments |
AU16979/99A AU1697999A (en) | 1997-08-19 | 1998-08-17 | System and method for increasing the durability of a sapphire window in high stress environments |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/914,842 US6123026A (en) | 1996-11-12 | 1997-08-19 | System and method for increasing the durability of a sapphire window in high stress environments |
US08/914,842 | 1997-08-19 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO1999010237A2 true WO1999010237A2 (en) | 1999-03-04 |
WO1999010237A3 WO1999010237A3 (en) | 1999-05-27 |
Family
ID=25434843
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1998/017072 WO1999010237A2 (en) | 1997-08-19 | 1998-08-17 | System and method for increasing the durability of a sapphire window in high stress environments |
Country Status (6)
Country | Link |
---|---|
JP (1) | JP2001502045A (en) |
KR (1) | KR100381686B1 (en) |
AU (1) | AU1697999A (en) |
CA (1) | CA2267562A1 (en) |
TW (1) | TW432197B (en) |
WO (1) | WO1999010237A2 (en) |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3052096A (en) | 1958-09-08 | 1962-09-04 | Vladimir H Pavlecka | Gas turbine power plant having centripetal flow compressors and centrifugal flow turbines |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4080534A (en) * | 1977-01-28 | 1978-03-21 | Bell Telephone Laboratories, Incorporated | Infrared detection and transmission apparatus |
US5206083A (en) * | 1989-09-18 | 1993-04-27 | Cornell Research Foundation, Inc. | Diamond and diamond-like films and coatings prepared by deposition on substrate that contain a dispersion of diamond particles |
JPH03177800A (en) * | 1989-12-05 | 1991-08-01 | Sumitomo Electric Ind Ltd | Pyramid dome for infrared sensor |
WO1992001091A1 (en) * | 1990-07-10 | 1992-01-23 | Saphikon, Inc. | Apparatus for growing hollow crystalline bodies from the melt |
JPH04151500A (en) * | 1990-10-16 | 1992-05-25 | Mitsubishi Heavy Ind Ltd | Protection device for infrared ray transmitting window of high-speed flying item |
DE4112140A1 (en) * | 1991-04-13 | 1992-10-15 | Bodenseewerk Geraetetech | SEARCH HEAD COVER FOR STEERING AIRCRAFT |
EP0529963B1 (en) * | 1991-08-22 | 2000-04-26 | Raytheon Company | Crystal growth process for large area GaAs and infrared window/dome made therefrom |
US5425983A (en) * | 1992-08-10 | 1995-06-20 | Santa Barbara Research Center | Infrared window protected by multilayer antireflective coating |
JP2713242B2 (en) * | 1995-05-31 | 1998-02-16 | 日本電気株式会社 | Dome for flying objects |
-
1998
- 1998-08-17 KR KR10-1999-7003397A patent/KR100381686B1/en not_active IP Right Cessation
- 1998-08-17 CA CA002267562A patent/CA2267562A1/en not_active Abandoned
- 1998-08-17 AU AU16979/99A patent/AU1697999A/en not_active Abandoned
- 1998-08-17 JP JP11514374A patent/JP2001502045A/en active Pending
- 1998-08-17 WO PCT/US1998/017072 patent/WO1999010237A2/en active IP Right Grant
- 1998-11-03 TW TW087113689A patent/TW432197B/en not_active IP Right Cessation
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3052096A (en) | 1958-09-08 | 1962-09-04 | Vladimir H Pavlecka | Gas turbine power plant having centripetal flow compressors and centrifugal flow turbines |
Also Published As
Publication number | Publication date |
---|---|
AU1697999A (en) | 1999-03-16 |
JP2001502045A (en) | 2001-02-13 |
CA2267562A1 (en) | 1999-03-04 |
WO1999010237A3 (en) | 1999-05-27 |
KR100381686B1 (en) | 2003-04-26 |
KR20000068784A (en) | 2000-11-25 |
TW432197B (en) | 2001-05-01 |
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