Just curious as to what the average time it takes for a mechanical head to open up after contact? What I was thinking is this.........even opening up instanteously upon the point contacting resistance, the arrow is already moving, so its obvious a little time and distance will have occurred before opening. Wouldn't a slower arrow open a hair quicker than a faster arrow? Have any studies been done on this?

Not bashing mechanicals....just looking for some information.

According to Rocket,it is just the opposite.

A larger cut head requires faster speeds so it will fly open quicker.I quess it could be described as springing open. I do not know if this is the reason for sure but it seems like I read it on their site.


Arthur did a poll on here a couple years ago asking about the success of mechanicals and although the poll was a small number of people,it seemed that the people with quicker setups had better results.

there are 2 types of mechanical broad heads. ones that open after penetration and ones that open at point of impact. if you check out the various types of mechanicals you'll see that this is based on there design. the point of impacts work better as they leave a hole at the impact point. leaving a better blood trail. good luck!!

hmmm.... that one took an extra bite of deer sausage to mull over!

OK, if I'm understanding your query right -- and I think I am -- the speedat which the action of the blades opening might change based on arrow speed, but the distance the arrow travels while opening would remain the same. I'll try to explain.

If the point of the blade has to come into contact with, let's say, deer hide, and that medium grabs the point and starts leveraging it backwards to open the blade into its full-width cutting diamter (I'm thinking of my Rocket Aeroheads here), it really doesn't matter how fast or slow the arrow is travelling -- just that the arrow has enough kinetic energy to absorb that action (and the resulting loss of energy absorbed by that act) and keep on trucking through. Whether that action happens quickly or on a more slower basis should be a moot point; it would happen in the same distance.

Is that kinda what you were thinking about?

I guess Greg(scratching my head) as I type this.[X(] I should go read 5shots tests again. I think what I really am after is how far will the arrow travel after impact before opening? I suppose that does depend on the design.

I see both sides of the coin on this one. I guess the only way to be sure would be to have a high speed camera and get the photos to look over. anyone whant to donate a camera? LOL it would be nice to have one, but I just ain't got the cash to dole out for one![]

I can tell you this , all the deer I have seen shot with vortex minimax heads , maybe 15 now , have had a 2" hole on impact and exit , and all have been passthrus . I dont know if its the design [probably] , being a 2 blade , and the fact that the blades swing freely , and are held by an o-ring

I don't know how long it takes them to open, but in my tests with Shockwaves, Rocket Steelheads and Rocky Mountain Assassins (once I got the Steelheads and Assassins fixed where they would open properly[>:])...

They all punched little bitty holes in the front side of a water-filled 1 gallon milk jug and they all made full cuts on the back side of the milk jug at 290 fps. 290 fps = 3,480 inches per second. With a milk jug being some 6" across, you're talking about fully opening within 17/10,000ths of a second.

But I'd imagine they'd open somewhat differently when contacting skin and flesh instead of plastic and water and at different speeds.

i believe that is so. All 6 deer I have shot with swing open mechanicals have had great, large entrance wounds. As large as any with a muzzy or TH. They punch nice big holes on the near side.

The bottom line is: regardless of whether a mechanical broadhead opens on impact or during penetration, they must open to function as a broadhead.