SITIS Archives - Topic Details
Program:  SBIR
Topic Num:  N07-094 (Navy)
Title:  RF Guidance Sensor Windows for High-Speed and Hypersonic Air Vehicles
Research & Technical Areas:  Air Platform, Weapons

Acquisition Program:  PEO(W) Strike Weapons and Unmanned Aviation (pre-milestone A, ACAT TBD)
 RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports): This topic is “ITAR Restricted”. The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign Citizens may perform work under an award resulting from this topic only if they hold the “Permanent Resident Card”, or are designated as “Protected Individuals” as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected.
  Objective:  Design and develop low-cost electromagnetic window/radome concepts that are capable of protecting guidance sensors at speeds of Mach 4 to Mach 6 at altitudes above 40 kft at cruise for 15 minutes.
  Description:  The heating effects of a high-speed/hypersonic vehicle (stagnation temperatures up to 2,700oF) associated with high-speed/hypersonic flight pose a difficult environment for sensors. The interface surface or window material must be able to withstand the high temperatures while affording transparency in the sensor’s electromagnetic spectrum of operation. Furthermore, the window may need to offer the sensor thermal insulation, cooling or protection from the vehicle’s external environment. Lastly, terminal homing seekers tend to have a forward-looking field-of-view, requiring an ogive-shaped window or radome that must endure the high stagnation temperature of these speeds, and the high dynamic pressures (2000-12000 lbs/sq ft). Given the altitudes and speeds that hypersonic vehicles encounter, RF sensors are deemed the most reasonable to perform as guidance sensors. There are 3 RF spectra of interest for high-speed/hypersonic vehicle guidance: Ka- through W-band for precision terminal homing, S- through Ku-Band for near-terminal guidance, and L-band for midcourse GPS navigation and guidance. The intent of this SIBIR is to have window materials and designs identified and tested which can be considered for use with RF guidance sensors in high-speed/hypersonic flight vehicles. For any of the spectra of interest, the window must: - Consider vehicle integration (thermal /structural/attachment) issues - Meet aero thermal and pressure loading conditions for vehicle flight profiles - Survive rain field conditions for vehicle low-altitude terminal guidance - Accommodate both flat and non-flat (conformal, ogive, faceted) surface shapes to match vehicle aerodynamic design - Maintain electromagnetic and thermo-mechanical properties associated with the intended guidance sensor

  PHASE I: Determine the feasibility of candidate materials for window application through material properties testing (transmissivity, structural strength, and thermal properties). Show how a high-speed/hypersonic guidance sensor window can be constructed, given the candidate material properties.
  PHASE II: Demonstrate fabrication techniques for the window materials in Phase I. Construct and evaluate through coupon testing, the performance and survivability endurance of a candidate window, in a relevant, supersonic/hypersonic environment. Consider multiple window fabrication and evaluation to cover some or all of the RF spectra listed above.

  PHASE III: Demonstrate commercial production capability for producing full-scale windows/radomes. PRIVATE SECTOR COMMERCIAL POTENTIAL/

  DUAL-USE APPLICATIONS: High endurance windows can support both land and airborne vehicles needing GPS guidance, or RF altimetry, or collision avoidance sensing.

  References:  1. Krell A., Blank, P., Ma, H., Hutzler, T., Van Bruggen, M. P. B., and Apetz, R. “Transparent Sintered Corundum with High Hardness and Strength.” J. Am. Ceram. Soc., 86, 2003, pp. 12-18. 2. Krell A., Blank, P., Ma, H., Hutzler, T., and Nebelung, M. “Processing of High-Density Submicrometer Al2O3for New Applications.” J. Am. Ceram. Soc., 86, 2003, pp. 546-553. 3. Krell, A., Baur, G., and Dähne, C. “Transparent Sintered Sub-µm Al2O3 with IR Transmissivity Equal to Sapphire.” Proc. SPIE, Volume 5078, 2003. 4. NAWCWD TP 6750-46, Vol 2, “Hypersonic Guidance”, 2001 5. NAWCWD TP 6750-47, Vol 2, “Hypersonic Guidance”, Apr 2002

Keywords:  Missile Dome; RF Dome; Hypersonic Missile; Ceramics; Ceramic Fabrication; SRBSN, Silicon Nitride, Seekers, Materials

Additional Information, Corrections, References, etc:
Ref #1 - 2: Available through online document delivery services IngentaConnect.
Ref #1 - 2: Available through online document delivery services IngentaConnect.
Ref #3: Available online through SPIE Digital Library.
Ref #3: Available online through SPIE Digital Library.

Questions and Answers:
Q: 1. The first three references you cite all report results for aluminum oxide. Is aluminum oxide suitable for this application?

2. Does it transmit sufficiently in the frequency/wavelength regions of interest to you?
A: . . . response pending . . .
Q: 1. What materials are currently being used for radomes?
A: There are many current radome materials:

(1) pyroceram (but a replacement material is needed since Corning is going out of this business)
(2) slip cast fuzed silica
(3) IRBAS (barium aluminum silicate)
(4) silicon nitride (many forms)
(5) DI100, DI200
(6) duroid
(7) ceramic matrix composites are being studied (as far as I know, these are not used for a radome in a current missile system)

There are others, of course.

The material always depends on the application and the aerodynamic performance needed.
Q: 1. The first three references you cite all report results for aluminum oxide. Is aluminum oxide suitable for this application?

2. Does it transmit sufficiently in the frequency/wavelength regions of interest to you?
A: . . . response pending . . .
Q: 1. What materials are currently being used for radomes?
A: There are many current radome materials:

(1) pyroceram (but a replacement material is needed since Corning is going out of this business)
(2) slip cast fuzed silica
(3) IRBAS (barium aluminum silicate)
(4) silicon nitride (many forms)
(5) DI100, DI200
(6) duroid
(7) ceramic matrix composites are being studied (as far as I know, these are not used for a radome in a current missile system)

There are others, of course.

The material always depends on the application and the aerodynamic performance needed.

Record: of