Sunday, April 8, 2018

Advancing to the next round...

Well, the dry spell for the Huntsville locale is over - we have a TARC team that is going to the national competition. The Saint John Paul II Longshots will represent their school at the flyoff in The Plains, Virginia on May 12; a win there will garner about 20,000 bucks of prize money and propel them into the international competition in London on July 20. Naturally, we are very excited for this first year team, and hopes are high!

The Longshots gather around their rocket, as "Benevolent Dictator" Duane looks things over (Click to enlarge).
Frankly, I didn't think they were going to make it - their best two qualification scores were a 21 and a 14.54, giving them a combined mark of 35.54. In the recent past, the cut off for making it into the top 100 teams was around 30, so I figured that the Longshots would appear on the list of alternates who would attend in case any of the top 100 didn't show. So I was both surprised and quite happy to see them make the finals, though it was a very near thing - the cut off this year was 35.56, just 0.02 higher than the Longshots' sum. Talk about the "hair of the chiny chin chin"! The Falcon Rocketeers had Huntsville's next best score - 36.04 (a 21.04 and a 15), which was just above the line, good enough to get them listed as the second alternate. So it is not outside the range of possibility that two John Paul II teams may make the late spring trek to Virginia; that would be totally awesome!

After the elation faded a bit, my nerd nature began to take over and I wondered if there was something in the Longshot's performance - as recorded in my notes - that may be useful in passing on to next year's teams. Even though I took much better notes this year compared to those of the past, there may be some missing data due to too much field activity. Nonetheless, a couple of things jumped out at me:

1) The Longshots fixed their design early, and the model (except for adding or taking away weight) did not change. It was your basic TARC rocket - nothing fancy, just good basic construction down to the nicely-sized fins and the very visible red and white paint scheme. I have seen other teams alter their model to improve stability (fins too small) or use a modular type construction that enables them to swap out damaged components. Stability is absolutely necessary, and in other arenas, modular would be a good thing, except that no two non-machine made components are exactly the same - different weights, different fin cross-section, etc.  These alter the performance characteristics, so swapping components is almost as bad as flying a new model each time. Hard to get consistent scores if the model flies differently each time.

The Longshots' rocket ("Phantom Flyer") leaves the pad powered by
an Aerotech F32 (Click to enlarge).
2) Of all the teams on the field, the Longshots were the most efficient - they moved through their checklist with increasing quickness, turning around the model in 30 minutes or so on the day of their final qualifiers. This is an advantage, as it minimizes the effects due to the rapid weather changes at Pegasus field in March. For example, the temperature gradient on March 25 and 31 was about 3 degrees per hour until early afternoon, with the wind slowly shifting its direction. Our teams record weather data, but I am not sure they know how to properly account for it, so being able to get flights off quickly improves consistency in the scores. The numbers show this clearly - On March 25, the Longshots were able to put 3 flights into the air for a mean score of 31 with a standard deviation of 28. They were much more efficient on March 31, flying four times for a mean score of 29, with a standard deviation of 14. The means are about the same, but the scatter is reduced by half!

TARC teams take note - make a good check list, and move through it quickly. An hour between flights will result in increase scatter in your scores.

Click to enlarge.
Those are tips for next season; for now, here's to the Saint John Paul II teams - may the Falcons get to join the Longshots on the TARC field of battle, and may one of them taste the fruits of victory!

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