The Hatra ballista: A secret weapon of the past?

Hart, V. G. and Lewis, M. J. T. (2010) The Hatra ballista: A secret weapon of the past?. Journal of Engineering Mathematics, 67 3: 261-273. doi:10.1007/s10665-009-9317-8


Author Hart, V. G.
Lewis, M. J. T.
Title The Hatra ballista: A secret weapon of the past?
Journal name Journal of Engineering Mathematics   Check publisher's open access policy
ISSN 0022-0833
1573-2703
Publication date 2010-07
Year available 2009
Sub-type Article (original research)
DOI 10.1007/s10665-009-9317-8
Volume 67
Issue 3
Start page 261
End page 273
Total pages 13
Place of publication Dordrecht, Netherlands
Publisher Springer Netherlands
Collection year 2011
Language eng
Abstract The mechanics and experimental work concerned with ancient catapults powered by torsion springs is described. Mathematical models are proposed both for the earlier Greek palintone, or stone thrower, and a supposedly more powerful machine based on the conjectured form of a notable find in the ruins of Hatra, a town in Iraq sacked in AD 241. For each of these machines an energy method is formulated together with differential equations governing their performance. Using a moment function derived in earlier work and allowing for internal friction, we solve the equations by numerical integration, assuming rigid straight arms and an inextensible sling. The ranges of projectiles launched from these machines are predicted, and the results are compared with observed ranges produced from physical models. Good agreement with experiment is found, confirming the superiority of the Hatra machine which is also more mechanically efficient. Comparison with some results of other workers on the bow is appropriate. In the course of this study it is found that the previously derived nonlinear relation between moment and angular displacement of a torsion spring gives much closer agreement between theory and experiment than a linear relation that was conjectured earlier. © 2009 Springer Science+Business Media B.V.
Keyword Catapults
Greek palintone
Ranges and mechanical efficiency
Theory and experiment
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Available online 26 August 2009

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
Official 2011 Collection
 
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Created: Sun, 20 Jun 2010, 00:04:27 EST