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Re: RE: PCSAT Cost and Satellites



Ah...Bob!

This is a subject I can get real close to...even if you don't build
satellites (and I have).

At 01:09 PM 3/31/2004 -0500, Robert Bruninga wrote:
>>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)...

He! He!  Well my solution (I have hand drawn my own schematics for
45-years) was to marry an engineering CAD designer with 30+ years
experience (15-years exp in assembly before that).  She does 3-D designs
for her company, and I bought her Auto-CAD with three symbol packs for
home!  She still knows how to work at a board, though, and manages all the
ECN's for the company, too.  Guess my napkin records will ge upgraded!

>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.

I messed with a design program an ran into that.  Drove me up the wall
trying to convince the program to do it my way :-)

>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...

BUT if I am to hire someone to really "make" something, I will always lean
to the "ham" engineer, because he has been a "technician" with dirty nails,
too!  Lots of paper-shuffling engineers (now computer slaves) in the world.

>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

So when Amsat looks for human resources, they really like to get someone
with "experience".

73s, Ed - AL7EB
PS:  I feel sorry for my employer when I retire...and for the poor fool who
inherits my "world".
Oh well, making $150/hour as consultant ain't bad for a retiree....LOL!
6-more years!


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