RE: Total arrow weight
 

I thought some more about my last, and I answered my own question......A tractor trailer hits harder than a pick up, even if the pick up were going alot faster.......Momentum, yes?

Ok.....BUT, we aren't talking about 60,000 pound trucks here....we're talking about an arrow w/ a good sharp broadhead on the front of it, and 57 GRAINS of weight difference.....With the flatter trajectory I'm getting now.....I think I'm in a win/win situation....

RE: Total arrow weight
 

MO,
I agree, the numbers sound crazy...that's why I don't like to use KE for much, if anything. The formula for momentum is weight x speed / 225218. According to your numbers, the heavier arrow is producing 0.5322 slug-feet and the lighter arrow is carrying 0.5065 slug-feet. This amounts to 5% less energry for the lighter arrow. When you combine this slightly lowermomentum of the lighter arrow with the fact that the heavier arrow will slow down less quickly over a given distance due to air friction, then the increase in momentum will be more like 8% for the heavier arrow over the lighter one. You are correct, however, that this is merely academic if deer is the largest game you will be hunting. But I'm hoping that I was able to make a complicated idea somewhat easy to follow so you can see why I choose the heavier arrow; that 8% gain may just be the amount that I need to get through a shoulder blade after apoorly placedshot. I practice every day to not need that extra, but I still consciously make the choice to take the best chance I have got to the woods. Good Luck!

RE: Total arrow weight
 

Ok, that's the FIRST time I've seen it explained that way, and the first time I've seen the formula for momentum.....I'm not sure what the heck slug feet are, but I can only guess them to be pretty slimy, much like the slug...[&:]

Actually, thank you a bunch, I understand perfectly now.....I was messin around w/ OnTarget2 last night, and the downrange speed difference of those 2 arrows isn't much, only like 4 fps if I remember correctly....Thanks again, great explanation!

RE: Total arrow weight
 

There is a problem with your numbers.You don't hardly EVER get an increase in ke when going lighter.



Usually there is another problem,like underspined arrows not being as efficient and/ or tune causing a problem.;).Didn't you have problems with this?



friction is idependant of speed once an odject is moving,faster DOES NOT mean more friction.

http://hypertextbook.com/physics/mechanics/friction/ you have to go way down to the bottom right before problems to read this statement.


I actually have a Machinist Handbook that staes that friction decreases as speed increases.Laws of dry friction.



But I would choose the heavier if I could get that kind of speed from a 425 grain arrow,hell,I don't get that from a 365 gr arrow.

RE: Total arrow weight
 

Being from Idaho I too likea heavy arrow for elk. For me a 400 grain arrow is light and I will not dip below that even though the arrowweightlaws changed for this year. We can now use a300 grain arrow,for all big game if weso wish provided we use a fixed blade broadhead.IMO thats way to lightno matter what the circumstances are,heck even a 450 grain arrow like my 7595'sgold tips XT's. Which are mycurrent elk arrows, are on the light side for elk. But on the flip side I sure wish I had a lightweight arrow set up just for antelope out of blinds where the shots can tend to be on the long side.Antelope are smaller than thewhitetails around here and their skin is very thin. Compared to mule deer and elk their bones are easy to slice, breakand penetrate, for most arrow broadhead combo's. Overallit doesn't takea lotKE for a pass throughon them.With that said I am in the process doing this right now for my switchback XT.That bow fully set up isa nice small package thats fitsperfect in blinds. My new Drenalin is comming soon and these last two years I have used the 05 Switchback as my main elk/deer hunting bow. So between them (Drenalin, 05 Switchback)I will have to decide what bow I really like the best for my main hunting bow and what bow will play the back up for this year. That's leaves the XT just sitting waiting to never get used unlessI make itinto aantelope hunting bow. lol Pathetic I know but hey I try hard to play will all the toys in the toy box. lol It might just be a good pay off too come fall!After all I can goantelope hunting knowing that I don't have to play switch a roo with my arrowsat the start of elk/deer season(august 30)which happens to be the middle of the antelope season(august 15 till september 15). In the pastwhen I have archery antelpe hunted I have always justused my elk hunting set up which is awesome under 40 yards. But longer than 40 yards my arrows that drop like rocks. Yes it should be nice, oh wait I just had another idea, maybe my antelope set up will also be a perfect turkey set up. :DWho knows?:Dlol

RE: Total arrow weight
 

KE is good, but its not everything. Momentum is much more important with regards to HUNTING. A heavier arrow will always penetrate better. For 3D and target, a lighter arrow with a flat trajectory is preferable, all you need the arrow to do is stick in the target.

For the smallish whitetails in the south, I don't think it matters much. But if you are going after those big northern/midwestern deer or any big game, I would take a heavier arrow in spades. You aren't giving up much by shooting 275 instead of 305. Your bow will be quieter anyway, and I'd rather have stealth than speed.

RE: Total arrow weight
 

Agreed, and yes, I did. BUT, when I changed to my lighter arrows they were also stiffer so I was able to increase the poundage a little to get it where I like it. The arrows I had before were indeed underspined, so I had to turn the poundage down quite a bit for them to spine properly....These new arrows also seem to transfer energy much more efficiently as well.

RE: Total arrow weight
 

With that kind of energy to be honest it doesn't matter. Both will be overkill for deer and most other animals in the states. I ran both arrows and the numbers are very close for both KE and momentum, and trajectory is fairly close at normal ranges as well.

As far as heavier arrows being quieter or having less shock, well at one time I would say that were true. Or if you were shooting a cheap or old bow. However with the newer bows and stuff we put on them I don't think it matters much. And that really isn't a super light arrow anyway. My bow will shoot arrows that weigh under 300 grns just as shock free and quiet as arrows that weight 500 grns. However I shoot a bowtech Mighty Might VFT that looks like a simms advertisement;). If I did the same thing on my 2000 darton yukon stripped down it would make a difference, but I honestly don't think a huge difference.

I would go with the arrow that spines best and shoots the best out of your set up. In the end that will be the most important thing.

Paul

RE: Total arrow weight
 

So please post this so that others don't get the impression that they can go lighter with arrows without changing anything and increase ke,this doesn't happen hardly ever.;)


The ke increased because the poundage increased.

RE: Total arrow weight
 

Yes, the KE increased because poundage increased, BUT, even before I increased the poundage the KE only dropped by 2 ft. pounds, and from 76 to 74 didn't really matter a hill of beans, especially when I figured in the added benefit of flatter trajectory.