01-02-2019, 02:12 PM
(This post was last modified: 01-02-2019, 07:34 PM by Brucicus.
Edit Reason: double posting
)
I hope everyone has had a great holiday!
My plumbata testing has continued over the past few days and I believe it is incumbent upon me to post my results whether good, bad, or indifferent. So I shall be doing that over the course of a few postings. I shall try to post all the relevant information and attempt to do so in a logical progression. Please feel free to critique or to ask questions.
Let's start-
I.) Test plumbata
The first order of business was to make a plumbata or two. So I did. One I used for testing and it remained unaltered during the tests. I named it 'Jove'. The other was a 'test bed' model which I used to test the effect of different weights, different shaft lengths, and different fletching/vanes. Only the results of the test model (Jove) will be reported here.
Below are two fotos of 'Jove' for your viewing pleasure.
Here are its vital statistics :
Components
Shaft - oak wood dowel (3/8th" diameter, 17" in length).
Weight - Two large steel nuts, each of which weigh 49g (98g total).
Fletching/Vanes - Cut from cardboard (Amazon delivery box) covered with duct tape for durability.
Binding Material - Glue, applied via a hot glue gun (a cruel mistress, indeed) and duct tape.
Total weight of finished dart - 135g
Aerodynamics
This test dart, Jove, is decidedly LESS aerodynamic than plumbatae used by the Romans. Here is how and why:
- 'Jove' utilizes steel for weight, not lead. Lead is much denser than steel, allowing one to use less lead in a smaller shape to achieve the same weight. Lead is much more malleable than steel and can be formed into aerodynamic shapes quite easily. The weights on 'Jove' present a large, flat face to the wind, creating resistance via its mass and its shape.
- Fletching is perhaps the most critical part of the dart's design. Proper fletching actually prolongs the arrow's flight, and as the plumbata is a weighted, thrown arrow, that applies here as well. Here is an article about arrow fletching that is very informative (https://www.advancedhunter.com/arrow-fletching/) should you be curious.
Feather fletching is also very light...ten times lighter than Jove's. Feathers are also much thinner and more aerodynamic (well, birds use them) than my cardboard vanes. Any mass in a plumbata that is not concentrated in the front weight is baggage and reduces the overall energy, thus distance or hitting power, of the dart. Jove's vanes provided guidance but offered much higher wind resistance, drag, and adverse weight effects than real feather fletching would.
So, in summation, the results of my testing represent the low end of plumbata performance. Significant improvements in ballast material and shape as well as the use of feather fletching would result in significant improvements in the numbers we achieved.
Need to break for a while. I'll be posting more soon.
Brucicus
My plumbata testing has continued over the past few days and I believe it is incumbent upon me to post my results whether good, bad, or indifferent. So I shall be doing that over the course of a few postings. I shall try to post all the relevant information and attempt to do so in a logical progression. Please feel free to critique or to ask questions.
Let's start-
I.) Test plumbata
The first order of business was to make a plumbata or two. So I did. One I used for testing and it remained unaltered during the tests. I named it 'Jove'. The other was a 'test bed' model which I used to test the effect of different weights, different shaft lengths, and different fletching/vanes. Only the results of the test model (Jove) will be reported here.
Below are two fotos of 'Jove' for your viewing pleasure.
Here are its vital statistics :
Components
Shaft - oak wood dowel (3/8th" diameter, 17" in length).
Weight - Two large steel nuts, each of which weigh 49g (98g total).
Fletching/Vanes - Cut from cardboard (Amazon delivery box) covered with duct tape for durability.
Binding Material - Glue, applied via a hot glue gun (a cruel mistress, indeed) and duct tape.
Total weight of finished dart - 135g
Aerodynamics
This test dart, Jove, is decidedly LESS aerodynamic than plumbatae used by the Romans. Here is how and why:
- 'Jove' utilizes steel for weight, not lead. Lead is much denser than steel, allowing one to use less lead in a smaller shape to achieve the same weight. Lead is much more malleable than steel and can be formed into aerodynamic shapes quite easily. The weights on 'Jove' present a large, flat face to the wind, creating resistance via its mass and its shape.
- Fletching is perhaps the most critical part of the dart's design. Proper fletching actually prolongs the arrow's flight, and as the plumbata is a weighted, thrown arrow, that applies here as well. Here is an article about arrow fletching that is very informative (https://www.advancedhunter.com/arrow-fletching/) should you be curious.
Feather fletching is also very light...ten times lighter than Jove's. Feathers are also much thinner and more aerodynamic (well, birds use them) than my cardboard vanes. Any mass in a plumbata that is not concentrated in the front weight is baggage and reduces the overall energy, thus distance or hitting power, of the dart. Jove's vanes provided guidance but offered much higher wind resistance, drag, and adverse weight effects than real feather fletching would.
So, in summation, the results of my testing represent the low end of plumbata performance. Significant improvements in ballast material and shape as well as the use of feather fletching would result in significant improvements in the numbers we achieved.
Need to break for a while. I'll be posting more soon.
Brucicus
