Dirt Nap DRT Single vs Double Bevel BROADHEAD BATTLE

[Bowhuntr64]

Now this is a fun one. Check it out. I have a similar one comparing Iron Wills coming soon.

 

[Ryan]

I find the amount of spin on the single bevel interesting. Sometimes people make a big deal about how much spin and increases trauma single bevels do because of the spin. But 25 degrees over 10 inches isn't much. In that case four laded heads cause a more trauma. That said these are four blade heads so the bleeders may increasing friction and decreasing the spin. A comparison of Grizzly single edge vs Grizzly Bruin (Double edge) would clear that up.

 

[firehuntfish]

I find the amount of spin on the single bevel interesting. Sometimes people make a big deal about how much spin and increases trauma single bevels do because of the spin. But 25 degrees over 10 inches isn't much. In that case four laded heads cause a more trauma

The "spin" that a single bevel, 2-blade broadhead generates is designed to have two-fold effect. The main benefit from the single bevel design is to create mechanical leverage to aid in splitting bone and not necessarily to create more trauma in the would channel. Dr. Ashby proved that certain single bevel designs actually do achieve this quite well in repeated testing on actual animal bone.

The second benefit from the spin generated by a single bevel design is that it helps to initiate immediate shaft rotation as soon as the nock leaves the string which greatly aids in quicker shaft recovery and better accuracy.

That said these are four blade heads so the bleeders may increasing friction and decreasing the spin.

Great point and it begs the question why bother to make this broadhead in a single bevel if you are going to install bleeder blades that would likely significantly diminish any rotation created by the single bevel in the first place. It's a gimmick that contradicts the physics.

 

[Ryan]

The "spin" that a single bevel, 2-blade broadhead generates is designed to have two-fold effect. The main benefit from the single bevel design is to create mechanical leverage to aid in splitting bone and not necessarily to create more trauma in the would channel. Dr. Ashby proved that certain single bevel designs actually do achieve this quite well in repeated testing on actual animal bone.

The second benefit from the spin generated by a single bevel design is that it helps to initiate immediate shaft rotation as soon as the nock leaves the string which greatly aids in quicker shaft recovery and better accuracy.



Great point and it begs the question why bother to make this broadhead in a single bevel if you are going to install bleeder blades that would likely significantly diminish any rotation created by the single bevel in the first place. It's a gimmick that contradicts the physics.

The bleeders are not a gimmick since they will assist in cutting more within the cutting diameter of the blades while the single bevel appears to help split any bone better. I'll take that any day. Though I'm not a huge fan of how this broadheads bleeders were placed within the ferrule. Seems to create a weakness.

Anyway, good tests.

 

[BSO Dave]

The bleeders are not a gimmick since they will assist in cutting more within the cutting diameter of the blades while the single bevel appears to help split any bone better.

@Ryan,
The bleeders do appear to be a gimmick on this particular design. The bleeder blades will hinder the ability of the single bevel to rotate which is the entire point of the single bevel design in the first place. If they wanted to add them to the double bevel design that's fine, but on a single bevel head it kinda defeats the purpose.

As @firehuntfish mentions, Ashby has done the work on this extensively and proved that single bevel designs absolutely create rotation and have a distinct mechanical advantage when the angle of the bevel is of a certain degree. Adding mass to the design in the form of bleeders or even a bulky ferrule would certainly create momentum robbing friction.

 

[Ryan]

@Ryan,
The bleeders do appear to be a gimmick on this particular design. The bleeder blades will hinder the ability of the single bevel to rotate which is the entire point of the single bevel design in the first place. If they wanted to add them to the double bevel design that's fine, but on a single bevel head it kinda defeats the purpose.

As @firehuntfish mentions, Ashby has done the work on this extensively and proved that single bevel designs absolutely create rotation and have a distinct mechanical advantage when the angle of the bevel is of a certain degree. Adding mass to the design in the form of bleeders or even a bulky ferrule would certainly create momentum robbing friction.

I wonder if bleeders to the rear would work out better. Like the Kudupoint + version. Also makes for a stronger ferrule.

 

[BSO Dave]

I wonder if bleeders to the rear would work out better. Like the Kudupoint + version. Also makes for a stronger ferrule

I get what you are saying, but if you are choosing a single bevel design specifically for its superior ability of splitting bone, I wouldn't want anything that would add friction including bleeders or a bulky ferrule that isn't tapered to reduce friction.

If your goal is to maximize trauma and penetrating bone is not the paramount concern, there are lots of other broadhead designs that will do that better than a single bevel, 2-blade design with or without bleeder blades. If you can't penetrate the ribs on a Cape buffalo for example, there won't be a wound channel to concern yourself with...