Direct Non-electronic Staging from Reloadable Composite Motors to Black Powder Motors
NAR # 71767
The objective of this study was to determine whether direct pyrotechnic staging, without the use of onboard electronic ignition systems, could be used to reliably ignite a black powder (BP) sustainer motor from a reloadable ammonium perchlorate composite propellant (APCP) booster motor.
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Placed "just outside" the top four trophy places
The Relationship between Super-Roc Length and Drag Coefficient: Rocksim Erroneously Suggests That Size Matters
Jay G. Calvert
NAR # 71767
The effect of super-roc length on drag coefficient, peak altitude, and super-roc altitude event scoring was determined empirically (Phase I) in a series of test flights and compared to Rocksim simulations of the same models (Phase II). In Phase I, a D impulse super-roc equipped with a very small altimeter was flown in five different length configurations ranging from 48” to 120” (three flights in each configuration). The data shows a clear decrease in altitude with increased length, due to weight of the added airframe tube and increased drag. After adjusting for increased weight, the coefficient of drag (CD) was backtracked from the altitude data using Rocksim. CDs ranged from 1.31 for the shorter model up to 3.22 for the longest super-roc. The SRA scores (length times altitude) were remarkably constant over the entire range of allowed lengths, suggesting that there is no “best length” in this event. When the same rockets were carefully modeled in Rocksim, the predicted altitudes varied considerably from the observations. Rocksim underestimated the performance of the shorter rockets and overestimated the performance of the longer ones. As a result, Rocksim mistakenly indicates that a maximum length super-roc will have significant advantage over a medium or short super-roc in the same impulse category.
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Placed 3rd in C Division
Optimizing Rocket Shape to Maximize
Alexander “Beandip” Calvert
NAR # 77390
For my NARAM R&D project, I built four model rockets with the same weight and internal volume. I put an altimeter in the rockets and flew each of them three times. I recorded how high they went. My hypothesis was that the skinny rockets would go higher than the fat rockets because the skinny rockets have less drag. Fat rockets have more frontal area so they have to move more air out of the way. However, extremely skinny rockets tend to collapse or fold or bend while flying. A skinny rocket might also have too much surface drag. You have to try to make a rocket not too fat and not too skinny.
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Placed 3rd in A Division