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How to make a plastic radar dish from scratch?

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  • Member since
    July, 2017
How to make a plastic radar dish from scratch?
Posted by cornman21 on Thursday, July 27, 2017 11:25 PM

I have been building a scale model of the cassini spacecraft, using styrene card, rods, and some random tubes lying about. It has been going pretty well, nothing that challenging, however i can't find a way to build the massive radar dish on top. It has to be pretty big, about 5 inches in diameter. I know it may sound stupid but i was wondering if any of you have some suggestions for building a dish/cone.

  • Member since
    April, 2012
  • From: Florida USA
Posted by Striker8241 on Monday, July 31, 2017 8:32 PM

Hi, Cornman21,

A radar dish like that is actually a parabollic shape rather than a cone shape. If you go online, you can find a lot of sites that provide instructions on how to draw a parabolloic curve, or you may be able to find some cross section drawings you can use to make a template. Make two curves - one more pronounced toward the center for the inside of the supports, and one more shallow for the outside of the supports.The supports should be thicker at the center and thin at the tips. You'll have to experiment.

You can make the antenna supports from single strips of styrene (5 inches long in this case). There are usually not a lot of supports (10 is probably enough) because the actual structure had to fold up for launch.

I would make a circular disk about 1/2 inch in diameter for the inside of the dish and glue your supports to it with them radiating out from the center.

I don't know about the Casini antenna, but the surface of many space antennas is just a thin metallic-coated (usually gold) Mylar material.  You could use clear food wrap glued to the inside of the supports for this. To get the metallic sheen, you could spray a thin layer of gold spray paint over it.

As a last ditch effort, there are a lot of Lego space-related sets that have parabolloid antennas... ;)

Good luck!

Russ

 

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Tuesday, August 01, 2017 8:52 AM

Striker8241

Hi, Cornman21,

A radar dish like that is actually a parabollic shape rather than a cone shape. If you go online, you can find a lot of sites that provide instructions on how to draw a parabolloic curve, or you may be able to find some cross section drawings you can use to make a template. Make two curves - one more pronounced toward the center for the inside of the supports, and one more shallow for the outside of the supports.The supports should be thicker at the center and thin at the tips. You'll have to experiment.

You can make the antenna supports from single strips of styrene (5 inches long in this case). There are usually not a lot of supports (10 is probably enough) because the actual structure had to fold up for launch.

I would make a circular disk about 1/2 inch in diameter for the inside of the dish and glue your supports to it with them radiating out from the center.

I don't know about the Casini antenna, but the surface of many space antennas is just a thin metallic-coated (usually gold) Mylar material.  You could use clear food wrap glued to the inside of the supports for this. To get the metallic sheen, you could spray a thin layer of gold spray paint over it.

As a last ditch effort, there are a lot of Lego space-related sets that have parabolloid antennas... ;)

Good luck!

Russ

 

I have been saving a couple of those eggs that a brand of women's stockings come in, as I felt that  they might make solid antennas (sections- ends of each half).  For open mesh antennas, they could also serve as a jig to build up a built up panel after putting down something that would prevent the glue sticking to them.

 

Don Stauffer in Minnesota

fox
  • Member since
    January, 2007
  • From: Coatesville, Pa.
Posted by fox on Tuesday, August 01, 2017 10:19 AM

If my failing memory serves me correctly, outfits like Plastistruct (sp) and Evergreen sell all types and sizes of styrene domes used to make refinery tank tops and other various horizontal tank ends. Might be worth a try looking them up on the net. 

Hope this helps.

Jim  Captain

Photobucket Main WIP: Rebuild of Monogram 1/8 "Big Deuce" with 1/8 Pocher V-12 in rear - 10%

   On the Bench:   Revell 1/48 Ju 52/3m - 50%;  Revell 1/96 USS Kearsarge - 20% 

I keep hitting "escape", but I'm still here.

  • Member since
    June, 2014
  • From: New Braunfels , Texas
Posted by Tanker - Builder on Friday, August 04, 2017 9:38 AM

Cornman;

    I just recently picked up a parabolic antenna shape from a LEGO after - market store , Here in San Antonio , called " Bricks N Minifigs "  . It is about three inches across . You can drop stretched sprue over it and make your antenna . It is not styrene so you should not have problems .

    Now , if you are concerned ,Take the piece before starting and rub it thoroughly with W.D.40 and build away . The W.D. will act as a shield to the surface , between it and your sprue .

  • Member since
    May, 2017
  • From: Cape Town,South Africa
Posted by SafferScale on Friday, August 04, 2017 11:05 AM

unfortunately not the same scale but I used the lens of a compass for a comms dish for my Vietnam Diorama

 

 

  • Member since
    August, 2017
Posted by Pickelhaube on Friday, August 04, 2017 3:33 PM

Actually it is quite simple but will require lots of putty and sanding.

1. Cut a round circle out of styreene the size you will need.

2. Cut thin slices from center to outside like thin slices of a pie.

3. Glue the petals together to get you shape.

4. Putty sand and prime.

5. Repeat step 4.

 

Practice on a piece of paper may help.

  • Member since
    January, 2006
  • From: California
Posted by SprueOne on Saturday, August 05, 2017 10:14 AM

This modeler used the dish from the Voyager kit. Would that work for your model?

http://indymatrix.tripod.com/space/explore/models/cassini.htm

 

 

Anyone with a good car don't need to be justified - Hazel Motes

 

Iron Rails 2015 by Wayne Cassell

  • Member since
    September, 2012
Posted by GMorrison on Saturday, August 05, 2017 2:02 PM

Places like the Halloween Store, Rite Aid, CVS or Michaels are great for foraging for stuff.

 

  • Member since
    June, 2014
  • From: New Braunfels , Texas
Posted by Tanker - Builder on Monday, August 07, 2017 12:22 PM

Hey " G " ;

 Was that you buying the 1/32 scale looking spider web in the halloween store ?

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