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RE: PCSAT Cost and Satellites



>While your responses to the above question had a lot 
>of very good information for those of us who are newbies 
>to the satellite construction business, it did not really 
>address the question.

Yep, its a hard question...  Ill answer to the BB for what it's worth:

Well, a lot of what goes into a good design is just plain ole'
experience and is not something one just picks up easily
in a book.  It is tens of years of experience working along
side people that do it every day.    Probably 90% of the
knowledge is just plain old experience, and only 10%
of it is written down.  

Books are full of equations, but none of the equations
apply in almost any case.  Equations are just shorthand for
simplilstic cases of a few variables.  It is usually orders of
magnitude other things going on and other variables involved
that can not be easily reduced down to a cook book of rote.

The creative engineer has a "feel" for what is required and
only resorts to the computer and calculations when he
has to do the final analysis, document it and prove it to others.  
Its like music,  Anyone can write down the notes, but there 
is a world of difference as to how it can be played.

So, there is no easy answer to your question.  I use the
radio amateurs handbook for most EE and RF engineering
issues, and I keep my physics 101 book handy for things
like accelleration and gravity and springs and forces.

There is one book our students use called Space Mission
Analysis and Design, (Microcosm Press) that gives a good
overview and is a good bible, and full of equations and
practical problems, but again, when used without experience
gives only text-book solutions.  The problem is not in knowing
the right equation, but in knowing all the ways that any given
equation is NOT a fully satisfactory solution to the real world
problem at hand.
 
For Engineering Drawings (most students can't make an
engineering drawing any more.  THey think Power Point
is all they ever have to do for any project)...

I use the super simple PAINT built into every windows PC 
for all my drawings!  Afterall, an engineer MUST be able to
design with a pencil.  The formal drawing is only to make it
presentable. PAINT is just an electronic pencil and 
perfectly adequate as a tool.

For an example, see my

http://www.ew.usna.edu/~bruninga/ande/ANDEtxrx.gif
http://www.ew.usna.edu/~bruninga/ande/ANDEwire.gif

I avoid the fancy "tools" that help one make fancy drawings,
because, one rarely has access to them when they need them
and I see all too often the totally WRONG results when
inexperienced people use them.  There is too steep a learning
curve for just simple use in a one semester project and the 
programs try to "help" the drafter too much such that the 
drafter loses responsibilty for the detail.  You end up with 
excellent drawings that are dead wrong... and cannot be 
used to build anything.

Just understanding screws and fasteners is a course in itself.
Anyone who tinkers in his shop knows what size screw is
about right for what kind of materials and forces, but if you
have to use a book, then its an extrordinary tediious process.

So yes, read the books, but the real key is to somehow
gain experience working alongside those that do it for a
living and watch how they do it...

When we built PCSAT2 in a clean rooom alongside a team 
of full time paid engineers at the Navy Research Labs (been 
doing it for 40 years) it was a real eye-opener compared to 
how we built PCsat1 on my desk.  ANd it shows why the
right way costs about 50 times more...

SO the book we call S.M.A.D. above is the only 
"resource" I can think of other than Ohms law, Keppler's laws
and Newtons laws.

Hope that helps.
de WB4APR, Bob


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