Continuing with the arrowdynamics theme, today we take a look at what is happening with a broadhead. The broadhead model I decided to use was one modeled after the Montec broadhead. I chose this one for several reasons, among them the fact that the Montec is a one piece broadhead which makes the geometry easy to model and the chance of strange things happening in the analysis minimal. Also, I have used the Montec and was curious about how it would perform.
The first image shows a pressure plot of the broadhead from the side with the pressure plot going through the center of the arrow. What was a bit shocking to me was how big of a high pressure area built up in front of the broadhead. I had assumed that the cut on contact head and very sleek/sharp design would minimize this up front area. There is also high pressure in the gaps of the blades. Low pressure areas are between the the blades near the head and of course immediately behind the blades. The low pressure areas behind the blades are very big and as discussed in the previous post, cause a backwards suction on the base and slow the arrow down.
This view shows is looking straight down from the top of a blade with the pressure plot running through the center of the arrow again. The low pressure areas really show up well in this plot and show the fairly large area behind the blades that will contribute to slowing the arrow down.
The final drag force on the entire arrow assembly was 0.03342 lbf. This is well over two times the highest drag that the arrow using the EZ-pull tip experienced. I would be very curious to hear what broadhead designers consider when creating a new broadhead besides the strength and cutting ability of the heads. Do they consider the drag forces in flight important? I plan on toying with improving this particular model to better match an actual Montec and then seeing what, if any changes could be made to it to decrease the drag forces and increase the arrow’s ability to maintain speed and energy during the flight.
Loading ...