Need help finding Hollow sphere to be used as radome

[mcglothlin]

I am on the APMIR team at the Naval Research Lab in Washington DC.<br>
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I have the need for at least one pair of hemispheres of 36 to 42 inches in diameter, having a thickness of between 3/16 to 3/8. I had envisioned using aluminum as the material, but am open to other materials. <br>
<br>
I have started looking into using tank heads, but they may not work out.<br>
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Sensors (a cluster of 4 to 9 passive microwave radiometers) will be enclosed in a hollow sphere which will be installed beneath a naval aircraft. The sphere will have cut outs through which the sensors will be able to record data from the ocean. Ideally, the sphere will be made of two hemispheres, with internal flanges, so that the outer profile is smooth. There is a possibility of either a fixed or a 2 degree of freedom mounting.<br>
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If anyone could provide me with information regarding products which could meet this application, or if you have any suggestions for me, please forward them to me.<br>
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Thank you,<br>
<br>
Norm McGlothlin<br>
<br>
Remote Sensing Division, Code 7223 <br>
Naval Research Laboratory <br>
4555 Overlook Avenue SW <br>
Washington DC 20375 <br>
<br>
EMAIL: mcglothlin@vaximg.nrl.navy.mil<br>
VOICE: (202) 767-8277<br>
FAX: <br>

 

[gromit]

You may want to consider using a non-metallic such as G-10 grade fiberglass, ABS or even polyester; G-10 being the best structurally. I have achieved several different radome shapes by having these materials vaccuum formed over wooden molds. The mold cost should be relatively low due to the simple shape, although the internal flange may have to added after so the finished shape can be released from the mold.<br>
Your wall thickness requirement is high for this type of process, especially the G-10. If possible you may want to look at a wall thickness of .13 or less for ABS or polyester and .06 or less for G-10. Raised ribs can be added to the hemisphere during the forming process to achieve the required stiffness of the radome.

 

[MadMango]

I've seen composite radomes made from a honeycomb substrate covered with fiberglass, on the order of 3/16-1/4 inch thick. This seems to be the most common materials for a radome of this shape, at least that I have run across.

Have you tried checking with vendors such as Raytheon or Siemens? They might have radoms prefabricated that will meet your design criteria. No use reinventing the wheel... &quot;The attempt and not the deed confounds us.&quot;

 

[mcglothlin]

Thanks for all of your help. We ended up going with spun aluminum hemispheres. The radiometers have portals for them to look through with a low loss dieletric foam (closed cell) covering/plugging the holes.

We had test flights in Dec 2001 and just a few weeks ago in June 2002. The foam worked great -- we flew as fast as the P-3 should during missions, with no problems.

thanks again,

norm

NRL - APMIR
Washington, DC