# RMR motor stats 1996-2002

• posted

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 group anyway.

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 exclusively) 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 upscale.

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.

+McG+
• posted

snip

But what's it all mean? Less filling or tastes great? ; )

Randy

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Can't we all just get along? :)

• posted

If you look at my class, A is 1 thus 1/2A is 0 and 1/4A is 00. This is the old motor classification from way back before my time. So subtract 1 from all your class numbers.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

• posted

Floor wax or dessert toping?

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

• posted

Is the mug half full or half empty, and why can't we have a whisky shot with a beer chasser?

• posted

Or is your mug just too big?

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Oh my God, Can't we all just get along!? :)

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It's Both! It's SHIMMER

• posted

What it means is that the RMR crowd are mostly a bunch o' lightweights, typical modroc flyers. ;-)

Like I said in an earlier post, I don't have stats for my motor usage in 2003. But it was around 20-25 motors total, the biggest being a couple H73's, the smallest C's. Another RMR lightweight.... But I did scratch build a rocket just for those H73's called "Totally Glueless"--used machine screws with QT.

80 motors average? Sheesh, I'm WAY behind! Gotta start burning up A10's in the field out back! More motors, less filling, AND that BP smoke tastes great!

But there's hope--I haven't launched a single rocket yet in 2004 unless you count those consumer firework "helicopters" on New Year's eve. Not too late to start accumulating a pile of eviden.....er, statistics on what I really fly.... Heh. But this year is going to be highly out of the ordinary for me. The stats will be very strange.

+McG+
• posted

Sorry for any confusion in the size class numbering.

When I started doing this kind of analysis of club data I used the default "option base zero" in Mathcad which starts subscripts in vectors and arrays at zero. And 1/4A was the smallest motor except for a rare MM that someone would launch just for the 'cool' factor. If I had chosen "option base 1" my classes would have been different by two from yours. I wasn't aware of the old style motor classification you use.

So that makes Micro-Maxx class 0000? Nah, the whole world should change to fit MY numbering scheme.... ;-)

+McG+

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NO!

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

• posted

Compared to whom? The Gates Brothers? Or the typical Questes rocketeer.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

• posted

Well, 000 actually...

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

• posted

what? and spoil all the fun?

hey, I'll sacrifice my own flight if you need my supplies, but don't tell me I can't argue with you. That wouldn't be be American! ;)

- iz

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I've seen that frequently. I recall a few NARAMs back, whin IIRC Tom Campbell pranged his scale model. Most of his competitors, including George Gassaway were helping to rebuild the model. I know I supplied a film can of lead shot for added nose weight. There's not much someone wouldn't do on the rocket range to help out another modeller, regardless of what you see here.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

• posted

Then you're right at home on rmr. It's as American as it gets. ; )

One very good example of why this is a great hobby.

Randy

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The Gates brothers *are* lightweights, just ask NASA!

The OregonRocketry desert launches are fairly evenly divided between low an high power in terms of numbers of flights. The RMR data looks more like the OregonRocketry launches at its grass seed field site, which is currently limited to FAR 101 but used to have a high power waiver. What I'm used to seeing at organized launches is more high power flights than the RMR proportions.

Dunno how accurately the RMR motor data reflects nationwide usage. Probably still far more high power activity than nationwide, given Estes sales. But what I keep seeing is that while the proportion of low vs high power varies, the mean and standard deviation of the two groups is fairly constant. Two distinctly different styles of rocketry, not one continuum. And the low power group is very much the "Questes" style. But high power isn't really as "high power" as people might think.

One other thing that jumps out of the data is that the 62.5 gram limit cuts the "high power" mode right down the middle. So much for "insignificant" impact! So far, that effect of that limit isn't even discernable in the motor usage statistics. Which means that in a

*practical* sense, Jerry is right, 62.5 has meant nothing thus far.

Must be damn frustrating to BATF! :-)

+McG+
• posted

But the real dividing line today is not 62.5g but LEUP. Easy Access reloads cover all of the H and I category, and some of the J. If and when Easy Access is eliminated, it will have serious impact on HPR. The price of entry and amount of effort to get into HPR will increase an order of magnitude.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

• posted

Snip absolutely nothing!

"But the real dividing line today is not 62.5g but LEUP."

- Bob Kaplow

1. NAR requires LE*P
2. TRA requires LE*P
3. Magnum requires LE*P
4. Aerotech requires LE*P
27 CFR 555.141-a-8 (the law) exempts all propellant actuated devices from the LE*P requirements in full.

ALL THE ABOVE ENTITIES HAVE TO DO TO SOLVE THE PROBLEM IS FOLLOW THE LAW. STARTING TOMORROW AND UNTIL THE LAW IS CHANGED.

LISTEN TO JERRY IRVINE

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