The Weighted Atlatl and Dart: A Deceptively Complicated Mechanical System
Author(s): William R Perkins
J. Whittaker: Began experiments as engineering student 1984, presented this paper Montana Arch Soc 1989, Perkins and Leininger 1989.
Atlatl is to propel light flexible dart, not heavy spear, tip of atlatl moves faster than hand, so dart faster than hand-thrown spear. Force is applied at end and dart flexes, similar to arrow.
Flex of dart is essential to spring spear off hook before atlatl decelerates and swings down, or would just slip off hook [which in effect is what happens.]
Dart flex stores and uses "harmonic oscillation and transverse waves" [a more complex explanation of concept of dart as spring]. Dart mass and distribution of mass affects flex, projectile point mass important part of this. “The dart is a missile which works very much like a spring.”
Recommended darts: Red ossier dogwood saplings, 160 cm long, 1 cm thick, 100 grams mass.
Atlatl length affects arc length: longer atlatl better for long distance.
Weighting an "average" atlatl (= 1/3 dart length) compensates and allows adjustment for distance.
Atlatl flexes, influenced by weight, which by affecting flex, times separation of dart and atlatl, so tuning proper flex of dart to atlatl makes system efficient.
[This theory was quite reasonable, but relies on a couple incorrect assumptions: 1. that the atlatl decelerates, allowing dart to release spring tension and jump ahead of atlatl, 2. that dart flex acts as compressing spring (in fact most of the available energy is released side to side by oscillation, not forward). Accordingly, weights may or may not influence flex of the atlatl but that is irrelevant, and while a flexible dart is necessary, it is not a spring system, and to speak of the dart “propelling” its point is quite wrong. See Whittaker and Maginnis 2006]
Cite this Record
The Weighted Atlatl and Dart: A Deceptively Complicated Mechanical System. William R Perkins. Archaeology in Montana. 31 (1): 65-77. 1992 ( tDAR id: 423393)
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min long: -129.199; min lat: 24.495 ; max long: -66.973; max lat: 49.359 ;
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Rights & Attribution: The information in this record was originally compiled by Dr. Roeland Paardekooper, EXARC Director.