Since I first found out about the Plumbata, I have wondered two things: what is the best way to throw it and how far can I throw it? I have not yet finished construction on any of my own Plumbata, so I have not been able to conduct any flight tests. What I have done is research other’s testing of this weapon. I found two papers written by Robert Vermaat from The Netherlands. The first was a summary of results from his 2007 series of throwing tests. The second was from a series of tests he conducted in 2011. Vermaat tested several commercially made Plumbata for distance using both underhand and overhand throws.
I also found a paper written in 2010 by John Emery as part of his Bachelor of Arts of Archeology for the University of Wisconsin-La Crosse. He also considered the distance of flight for both over and under hand throws. For his tests he manufactured his own plumbata based on images and descriptions from period sources. Unlike Vermaat, he did not throw the weapons himself. He recruited, and trained, a group of volunteers who threw the weapons so he could focus on making observations and taking measurements.
These researchers used Plumbata that were different in size and weight so the results they produced vary greatly but there were some similarities. Both found that underhand throwing produced longer throws and required much less energy. They also found that, with practice, greater distances could be achieved.
In Vermaat’s first series of tests he found that in all cases, and with all weapons, underhand throwing produced the greatest distances. These differences varied by from 4 to 9 yards depending on the particular weapon used. His average distance for underhand throws was 35.9 yards, (108 feet). For overhand throws the average was 32.6 yards (97 feet). In his second set of tests in 2011, with different weapons, his averages were 35.4 yards underhand (106 feet) and 32.6 yards overhand (98 feet).
Emery conducted two sets of measured tests after several practice sessions. During these initial sessions he discovered that the overhand throw produced results significantly different than the underhand throws. These initial tests were not measured but he estimated the overhand throws averaged somewhere between 110 and 120 feet based on his pacing of the distances. This was 40 to 70 feet shorter than the underhand throws so he decided to end testing of the overhand method. His first series of tests produced an average distance of 170.9 feet. The second set resulted in an average of 173.7 feet and included multiple throws over 200 feet. Emery also noted that his longest throws resulted from the smoothest releases which produced less in-flight wobble. These were also the last throws that were made after the throwers had the most practice.
For his trials, Vermaat used Plumbata that were longer and heavier than Emery. The fletching on his commercially made weapons was disproportionately larger than those used by Emery and this increased drag may help to explain some of the differences in distance achieved.