Some Thoughts on "Home-Made" Engines

Some Thoughts on "Home-Made" Engines

Post by Mark Bundi » Fri, 18 Mar 1994 22:15:20




Quote:
Matthew Guslick) writes:
> How big would a typical rocket have to be to be spotted on radar?

Wallops Island Storytime again, boys and girls.

Back in my college days during the summer, I went over to the Wallops range  
control center (second floor, Hanger N-159) to watch a night shot.  My dad  
ran the launch.  About T-2 minutes, the transponder aboard the vehicle went  
out.  My dad turns to the project manager, reports this and says "what do you  
want to do?".  Replies he, "can you skin track it".  "We'll try, but I can't  
guarentee it."  The project manager says go ahead and launch.  The Wallops  
crew proceeds to skin track the vehicle all the way to its impact 600 miles  
downrange.  Cheers, and backslapping all around.

When I querried Dad afterwards, he said that track was the exception, not the  
rule.  The cross sectional area of a sounding rocket, considerably larger  
than anything discussed in this thread, isn't that much for a radar to  
handle.  And I suspect that equation gets worse when we're talking about  
general coverage radar systems, like those employed in air traffic control.

=========================================================
Mark B. Bundick         "Running a NARAM will never be harder
NAR Vice President      than building a nice scale model"

 
 
 

Some Thoughts on "Home-Made" Engines

Post by Rusty Whitm » Fri, 18 Mar 1994 21:19:00


Quote:


>Matthew Guslick) writes:
>> How big would a typical rocket have to be to be spotted on radar?

>Wallops Island Storytime again, boys and girls.

>Back in my college days during the summer, I went over to the Wallops range  
>control center (second floor, Hanger N-159) to watch a night shot.  My dad  
>ran the launch.  About T-2 minutes, the transponder aboard the vehicle went  
>out.  My dad turns to the project manager, reports this and says "what do you  
>want to do?".  Replies he, "can you skin track it".  "We'll try, but I can't  
>guarentee it."  The project manager says go ahead and launch.  The Wallops  
>crew proceeds to skin track the vehicle all the way to its impact 600 miles  
>downrange.  Cheers, and backslapping all around.

>When I querried Dad afterwards, he said that track was the exception, not the  
>rule.  The cross sectional area of a sounding rocket, considerably larger  
>than anything discussed in this thread, isn't that much for a radar to  
>handle.  And I suspect that equation gets worse when we're talking about  
>general coverage radar systems, like those employed in air traffic control.

Point Defense Systems on ships can detect and engage incoming missiles
with pretty small radar cross sections.  Think of an Exocet coming at
you head on at almost 600knts.  Anyway, the answer to the question
as to how big the rocket would have to be to show up on radar depends
on the radar.  NORAD (are they still called that?) tracks some pretty
small pieces of junk in orbit.  I forget what the smallest piece is
that they track but its small.  Someone probably knows this piece of
trivia.

Rusty Whitman - [NAR 48599, TRA 2787]

 
 
 

Some Thoughts on "Home-Made" Engines

Post by Mark Bundi » Sat, 19 Mar 1994 22:30:38



Quote:

> Point Defense Systems on ships can detect and engage incoming missiles
> with pretty small radar cross sections.

Remember the equipement at Wallops isn't necessarily state of the art.  Much  
of what they used up until about the time Dad retired 5-6 years ago was  
"leftovers" from other NASA or military installations.

=================================================================
Mark B. Bundick         "Running a NARAM will never be harder
NAR Vice President      than keeping NAR history straight"

 
 
 

Some Thoughts on "Home-Made" Engines

Post by Robert Wasiers » Sun, 20 Mar 1994 04:34:37


stuff deleated

Quote:
>     BTW, the exact physical size is nowhere near as important as the
>reflective charactaristics - put in lots of right angles, and any
>metallic object will show up on radar.




        Not if it's smaller than the wavelength of the emmission, the
        modes that can exist on an object smaller than a wavelength
        start to diminish rapidly and make it difficult to get a useable
        return.
 
 
 

Some Thoughts on "Home-Made" Engines

Post by Russell Pant » Sun, 20 Mar 1994 03:46:18



[Much deleted...]

Quote:
>  NORAD (are they still called that?) tracks some pretty
> small pieces of junk in orbit.  I forget what the smallest piece is
> that they track but its small.  Someone probably knows this piece of
> trivia.

     Sorry, I left my sources at home, but I am writing a research
report on orbital debris.  The space detection network can detect
spheres down to about ten centimeters in LEO by radar.  They also can
detect using optics, and use a dual 1 meter scope to see ten
centimeter stainless steel spheres in GEO - 10500 miles away!
     BTW, the exact physical size is nowhere near as important as the
reflective charactaristics - put in lots of right angles, and any
metallic object will show up on radar.



 
 
 

Some Thoughts on "Home-Made" Engines

Post by bak.. » Sun, 20 Mar 1994 07:36:13


: When I queried Dad afterwards, he said that track was the exception, not the
: rule.  The cross sectional area of a sounding rocket, considerably larger  
: than anything discussed in this thread, isn't that much for a radar to  
: handle.  And I suspect that equation gets worse when we're talking about  
: general coverage radar systems, like those employed in air traffic control.

It also depends on the type of radar.  Most ATC radar is optimized for
picking up mode C transponders -- They can even miss light aircraft.

______________________________________________________________________________
                                     | Michael J. Bakula
            Fast or slow,            | UNIX Systems Administrator
       oxidation is my friend.       | The Institute for the Learning Sciences

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 
 
 

Some Thoughts on "Home-Made" Engines

Post by Jim Co » Wed, 23 Mar 1994 03:04:10


I believe that the Model Rocketeer (precursor to Sport Rocketry
magazine) published an article by Trip Barber on this very topic in
the early 1980s.  There was real data here (real rockets and real
radar).

J