Model Forum / General / Rockets / May 2004

Chuck, sounds pretty interesting. Did you include any shots of large
breasted women? The average guy can handle anything if it has big breasted
women. It worked in the Air Force. When we were studying atmospheric physics
at forecaster school, every ten slides or so had shots of scantily clad
babes with big chests. No body fell asleep in those classes. Of course, that
was back in the dark ages when folks still had a sense of humor about such
things.

OK, seriously though, I think it's a great idea even without the cheesecake.
I wonder though if the rank and file would have sufficient science
background to be able to apply any of what you discuss. Application is the
rub. If the typical Sp Rocketry reader can't apply the information to what
he/she is doing then the article will bomb. You may have to tilt the article
very heavily toward practical application for it to have any appeal.

I think it would be a great article. This type of information is
normally way beyond what I "need" to know, but I always find it
interesting. I think you did a good job explaining the physics in your
altitude chamber article; it wasn't too difficult from someone without
a heavy physics background (like me) to understand. Coupling the
physics explanations with a real-world altitude chamber makes it even
more effective.

I'd be very interested in other articles by you, or others, that cover
the science of our hobby.

Mario Perdue
NAR #22012 Sr. L2

for email drop the planet

http://roci.indyrockets.org

"X-ray-Delta-One, this is Mission Control, two-one-five-six, transmission concluded."

Chuck,

It didn't have too much math for me. But since I have an MSEE I might be biased. :-)

You had me excited with the curve fitting part for a minute but when I realized
that you were using a square root to get from pressure to altitude I relaxed. I
was looking for something better than a piecewise linear interpolation method
for this. But a square root is just as bad from a computational standpoint as
the standard equation.

Speaking of which, I have no clue why you bothered fitting a curve to that data
table as good equations are readily available:

http://www.grc.nasa.gov/WWW/K-12/airplane/atmos.html

Short answer:  WRITE IT!

I'd love to see this type of article, if for no other reason than it is
different from the run-of-the-mill type of stuff.

I would ask that you write it so that it's understandable at the 'smart
kid' level, but put additional stuff in a sidebar article for those of
us who do want to read it.  That way, it can be used as a teaching tool
for kids without being a problem.

David Erbas-White

Chuck,
I loved it.  I miss the tech stuff from the old MRm days.  Even though I
didn't understand the calculus then, that spurred me on to ask teachers what
those equations meant, and pointed me towards getting into engineering.  I
wish SpRocketry would put a little more tech back into rocketry.

Of course, I am a geek...my sig says it all

[snip]

Do it.  I'll explain the math to Randy.     ; )

Verna

Might point out that the typical "'good ground test" does not model
the separartion dynamics very well.  In a real free body event, the
rocket body is accelerated backwards, and the overall nc-body
separation velocity is reduced.  With the body fixed in a ground test,
a greater velocity is imparted to the nc.

At least that's the way it works out in my mind - somebody might want
to check me on this.

GC

chuck:
the more the merrier....I am re-reading the article again and again to soak
it all in ....

shockie B)

Chuck,

After reading this r.m.r. post I was anxiously awaiting my bulk mail
delivery of SR which finally came yesterday.  Back B.K. (Before Kids) I used
to write tech filled articls for our club newsletter and Extreme Rocketry
(the "Rocket Science" articles) so I was dying to see how someone else
approached the subject.

I enjoyed your article and it seems we have similar styles: peppering the
tech info with hopefully entertaining quips and suggestions to the reader
that the equations and science really are not that difficult if they just
read along with you.  I always thought diagrams and figures were a must and
you fulfilled that requirement.  I started thinking about he old
descriptions of "what is pressure" in physics text books where they show
cartoons of air molecules hitting one another at different volumes but that
may have been going a bit too far so I think you had a pretty good balance
of showing enough to get your point across but not so much to be boring.

I never really got a lot of feedback on what I wrote except that Brent kept
asking for more stuff for ER and once in a while someone would send in a
letter saying they like the tech features.  Good idea you asking here, I
never thought of it.

How much time did the article take you?  That has been my problem the past
couple years in trying to find time to write these things (I still have
several ideas, but no time!!!)  I know I must have spent well over a hundred
hours on the article about supersonic flight for ER.  Between research,
creating diagrams and equations and then writing and re-writing things 4 or
5 times it all adds up.

Here's some links to NIRA club news letters I had articles in to give you
some samples of how someone else approaches tech writing for the masses.

http://www.nira-rocketry.org/LeadingEdge/JulAug99.pdf
http://www.nira-rocketry.org/LeadingEdge/MayJune00.pdf
http://www.nira-rocketry.org/LeadingEdge/JanFeb02.pdf

Looking forward to more articles from you... hopefully you have the time to
devote to them.

Good Luck

nOrM

Chuck, I thought your article was very well written; informative and
entertaining.  it was a great overview of the math too.

the women in my life are somewhat entertained by syringes and tubing and
mason jars and mathy articles.

looking forward to more like that from you!!

Sport Rocketry is a great magazine, especially for the size of the
distribution.

Thanks for the feedback.  I appreciate the positive and
not-so-positive comments that I've received both in this thread and
via email.  I will plan on writing some more similar techy articles
when I can scare up a little free time, which has come at a real
premium these few weeks.

Best regards!
Chuck

Chuck

Just finished the article and found it quite well done. A refreshing
distraction of pure theory applied to practical use. I've already laid out
my plans to "bash" your idea with a few "improvements."

The syringe as a vacuum source is novel, as I probably would have gone with
something more like your ill-fated brake tool.

One thing that might have made your figures a bit more accurate would have
been a more precise measure of the mason jar volume/ A simple graduated
cylinder would have helped a bunch.

Barring that, I would have got as close to 20 degrees C as possible and
weighed the jar full and empty. you could have then easily calculated the
volume by using a basic presumption that 1g of water = 1 cubic centimeter (I
think that is right, Any Chemists out there?)

A