It took a little work but I finally figured out Bob's clever format
for the summary information. Guess I passed the IQ test...(wink).
Anyway, using the motor totals for all seven years from his web site
and running them through my curve fit analysis to get a broad view of
RMR's 'style' of rocketry I get the following. What I call a "group"
can be viewed as a group of flyers but is more likely a "style" or
"attitude" of rocketry. I excluded Micro-Maxx because it's really its
own thing, and besides, including it would have screwed up the math.
The curve fit does in fact reveal that it would show up as a separate
The way I do the math, 1/4A is size class zero, 1/2A is class 1, M+ is
size class 14.
The low power group is characterized by a mean motor class size of
3.54 (halfway between B and C) and a standard deviation of 1.76
classes. The high power group is characterized by a mean of 8.21 (a
bit over G) and a standard deviation of 1.37.
Running a trimodal analysis refines these numbers only slightly. The
third group shows up as a small excess of 'C' motors(1 percent of
launches) forming a group with mean of 3.97 and a std. dev. of 0.12
size classes(effectively a small spike at C). The low power group
changes slightly to a mean of 3.43 and a std. dev. of 1.81 (75% of
launches)while the high power group becomes a mean of 8.11 and a std.
dev. of 1.55 (24% of launches). Overall this is a slightly better
fit, but both solutions are only an "ok" fit by comparison to what I
usually get. (On data from some local launches I've obtained trimodal
fits that were SCARY good!) In either solution the low power group is
obviously truncated at 1/4A indicating that it's not surprising that
they would fly 1/16A Micro-Maxx motors, although not in the numbers
reported. Like I said, Micro-Maxx is its own thing.
For comparison, data from OregonRocketry launches at our eastern
Oregon site breaks down into the following three modes:
Low power, mean 4.08 std. dev. 1.22, 43% of launches
mid-power, mean 7.44 std. dev. 0.57, 11% of launches (F and G
high power, mean 9.81 std. dev. 1.38, 46% of launches
What is interesting about this kind of analysis is that the observed
motor usage indicates that rocketry has not yet evolved into one
continuum of activity. The low power group essentially never flies
anything over a G motor. The high power group essentially never flies
anything smaller than a C or D motor. The "notch" at E is simply an
artifact of the way the low and high power groups overlap.
Another interesting point is that the bell curve model applies to
MOTOR CLASSES, not newton-seconds. The difference between the means
of the low and high power groups is 4.7 letter classes, translating
into a factor of 25.6 times increase in newton-seconds. But that in
turn translates into a linear scaling factor of about 2.95. IOW, the
difference between RMR's low power and high power groups is 3x
Maybe later I'll do some more number crunching on the data and look at
some other aspects of it. Meanwhile, posting more detailed info like
graphs would depend on exporting the worksheet from Mathcad +6.0
(involving complete reformatting) to an RTF file and uploading to
somebody's web site.
- posted 18 years ago