Speed... Curiosity only

[Tracker0721]

What I was thinking Del was the obsidian wasn't casting a shadow the same through each sensor so it'd be just like when shooting shiny pellets and causing the sensors to figure the wrong speed. That's why people color their pellets black at the nose when they're getting big differences in FPS. I was just spit balling with the feathers height. Didn't get to shoot today but will tomorrow.

[Drewster]

Seems so me like you're spending a lot of time worrying about arrow weight when you could be practicing your accuracy......and if you could hit where you need to, the arrow weight won't make any difference.

[BowEd]

Just a comparison here that is related.Years ago a big game hunter Elmer Keith solved the penetration problem for African big game by going with a heavier bullet for better penetration.Instead of a lighter bullet with more powder.Same principal with arrow shafts also.
Shoot an arrow in water once.It goes deeper with more punch than a lighter lead bullet.All because of the mass the arrow carries.
With archery what's most important overall is placement and flight amongst other things of course.When you get it all together it can count in a situation that needs it.
Flat shooting 11 grain per pound arrow at 20 yards is what I go for and use hunting.That's all I want to practice with too so I can become as accurate as possible since I'm not the best shot all the time.....lol..So my 52#@28" bows that I like to shoot will shoot a 560 to 580 grain arrow consistently somewhere around 155 to 160 fps.Some bows have shot better into the 170's.Those I'll shoot a heavier arrow yet into the 600's or more.Goal here is to enjoy the lighter draw weight with the punch of a heavier bow.

[Tracker0721]

Yes Drewster, I could be practicing accuracy but wouldn't you wanna know the optimum arrow weight for your bow? Then figure the optimum point weight to shaft weight? Haha I take it not but still! I mean, I practice my accuracy everyday. I was just curious at the start what other people where getting and if it could be used to make something primitive more modern. But now that Del brought up the point about an optimum spot, my curiosity wants to find it.

[Badger]

   Your optimum spot is easy to find. The heaviest arrow will always be the slowest yet carry the most energy. You need to find an acceptable arrow weight for the game you are killing that is fast enough to be accurate with. Your 475 arrow is plenty heavy enough for deer and gives you good speed, I don't think I would want to go below 150 fps so if I were in your shoes I would choose something about 500 to 550 grains.

[bigcountry]

I think some are getting energy and momentum mixed up a bit.  Energy out of a "system" should not change much but is dominated by velocity.  Hence why velocity is squared. 

But for primitive archery or even for compounders, momentum is king for penetration.   MassXvelocity.  That's the reason, most 45-70's will outpenetrate a 30-06, even if they have the same energy or even if 400gr projectile has less energy than the 150gr out of the 06. 

But momentum on the other hand is key for penetration.  Your 770gr arrow will carry more momentum. 

This is the age old argument folks have talked about around campfires, where you have one group, usually younger gen, who think super fast whiz bangs are best, and old timers like Col. Cooper always thought heavier is better.  I myself like to keep my arrows around 150-160fps, that way my mind does not have to totally retrain to shoot different bows.

[BowEd]

Tracer0721....The principals versus primitive to modern are the same.Don't know quite what you mean by that question making something primitive more modern.Your subject is tip toeing around making primitive bows efficient I'm gathering is what you mean.What Badger is saying is correct just from my limited experience compared to his since he has tested countless more bows than me.There can be quotes of deer shot dead with 350 grain arrows but I'm sure the placement was right.At close range it's practically irrelavent anyway [under 20 yards].The longer the distance shot the lighter arrow will lose more energy while the heavier arrow will maintain more when hitting the target.I don't have a graph to prove this just experience shooting things that's all.If I could be a crack shot at 50 yards that would be nice but I'm not.Not even close to that.....lol.When hunting I want as many things in my favor as possible no matter what.It's good you are shooting first off to find out that's what's most important too.You'll find out soon enough what pleases you.

[Del the cat]

I think some are getting energy and momentum mixed up a bit.  Energy out of a "system" should not change much but is dominated by velocity.  Hence why velocity is squared. 
...

What you say makes sense, but isn't actually quite right.
Look at the graphs I plotted...
Yes energy out doesn't change much, once you have a heavy enough arrow
You'd think the velocity squared would dominate... but below that optimum weight. it doesn't!
Again see the graph... with the lightest bolt I got over 200fps, but the energy (and momentum) was far less than the heaviest arrow.
That's the whole point of doing all those tests and plotting the graph.... to see where common sense and intuition breaks down and and the actual performance of the system takes over.
The optimum is the arrow that is getting close to that maximum energy, whilst having the highest velocity, and thus most momentum, which is what I think you were alluding to.
Taking it to the limit, the arrow with zero mass is fastest, but it has no energy or momentum
Del

[JW_Halverson]

I am still going to say the lighter arrow is THE best choice.  And here is my reasoning:
1) it has more than enough weight to penetrate a deer.  Deer are not armor plated, no matter what the .300 Win Mag shooters may think.  A sharp projectile moving at the speed of this arrow is more than sufficient to pass thru both sets of ribs and set the lungs to bleeding profusely.
2) a heavier arrow will suffer more drop on trajectory based on distance from the shooter to the target, requiring split second calculations and opening Pandora's box by adding another level of complexity. It's the plate spinner in the circus...he keeps adding plates and having to dash  back and forth to keep it all up in the air at once.  Great fun only happens when it all crashes to the ground. 

Fastest arrow with enough momentum and energy to penetrate is the simplest solution. 

[bradsmith2010]

I agree that the 150fps  is a good starting point for hunting arrow speed,, I have hunted with bows that shot faster and slower,, it is good to know what your hunting set up is doing,, for me,, I am going to limit my shot to closer with a slower bow,,and if the bow is faster,, I may stretch it out a few yards, but like to keep the shots close for hunting,,, once it gets past 15 yards a  deer can move quite a bit,, I like the closer shot with higher percentage of success,,   I used to shoot a sinew bow 65# at 25 and it would shoot a 500 grain arrow close to 180 fps,, and even then at close range the deer would often be in a different position when the arrow got there,, I experienced this many times,, and was always amazed ,,,, so the older I got the closer I shot,,

JW,,,, I agree with you,, but if you make your shot closer ,, the heavy arrow is still going to be effective ,, there will be minimum drop to 15 yards,,
I agree the faster arrow does give you a slight advantage,,,,especially if you plan to shoot say out to 25 yards,, for me I feel like once you get to that range,, accuracy and deer movement can be an issue that even the lighter arrow can't compensate for,,  I guess my point is , ,that the closer you shoot the less effect the arrow weight plays in taking the game,,, if both arrows shot great out of my bow it would be a toss up for me,, I would shoot the one that gave me the most consistent accuracy,,

[bigcountry]

I think some are getting energy and momentum mixed up a bit.  Energy out of a "system" should not change much but is dominated by velocity.  Hence why velocity is squared. 
...

What you say makes sense, but isn't actually quite right.
Look at the graphs I plotted...
Yes energy out doesn't change much, once you have a heavy enough arrow
You'd think the velocity squared would dominate... but below that optimum weight. it doesn't!
Again see the graph... with the lightest bolt I got over 200fps, but the energy (and momentum) was far less than the heaviest arrow.
That's the whole point of doing all those tests and plotting the graph.... to see where common sense and intuition breaks down and and the actual performance of the system takes over.
The optimum is the arrow that is getting close to that maximum energy, whilst having the highest velocity, and thus most momentum, which is what I think you were alluding to.
Taking it to the limit, the arrow with zero mass is fastest, but it has no energy or momentum
Del

Really, its whatever floats your boat, but in the fella's example of his two results momentum is higher with 770gr setup.  And with all things being equal, will out penetrate high lighter setup.  what many are not factoring in the fact is harder you hit a medium, the harder it hits back. The surface tension changes with velocity.  That's just physics.

[Mac43560]

Exactly JW.  An arrow is a cutting tool that creates a channel the same way other ones do.  There is negligible difference between temporary and permanent wound channels.  There is little shock in the sense a bullet would give a prey.  There is no conical wound expansion.  There is no "takedown" power.  A bow is not a gun, it's a bladed hole puncher.  Every deer I've shot has been a through and through.  You either hit the heart/lungs or you're going to be disappointed at one point or the other.  Accuracy and speed.  I can buy the cheapest hunting weight arrows I can and shoot it from my pse and as long as they don't explode upon release, I feel confident it will kill whatever animal you want if it's accurate.   Because it shoots twice the speed of my trad bows. 

[JW_Halverson]

I think some are getting energy and momentum mixed up a bit.  Energy out of a "system" should not change much but is dominated by velocity.  Hence why velocity is squared. 
...

What you say makes sense, but isn't actually quite right.
Look at the graphs I plotted...
Yes energy out doesn't change much, once you have a heavy enough arrow
You'd think the velocity squared would dominate... but below that optimum weight. it doesn't!
Again see the graph... with the lightest bolt I got over 200fps, but the energy (and momentum) was far less than the heaviest arrow.
That's the whole point of doing all those tests and plotting the graph.... to see where common sense and intuition breaks down and and the actual performance of the system takes over.
The optimum is the arrow that is getting close to that maximum energy, whilst having the highest velocity, and thus most momentum, which is what I think you were alluding to.
Taking it to the limit, the arrow with zero mass is fastest, but it has no energy or momentum
Del

Really, its whatever floats your boat, but in the fella's example of his two results momentum is higher with 770gr setup.  And with all things being equal, will out penetrate high lighter setup.  what many are not factoring in the fact is harder you hit a medium, the harder it hits back. The surface tension changes with velocity.  That's just physics.

But there is no bow built that will cause an arrow to suffer from those effects.  Hydrostatic shock is outa the realm of possibility even today, April 1st!

[jeffp51]

I really like the physics part of the archery too--not so much that I want to go out and buy a chrono or chart force draw curve, or anything,  but the intersection between theory and practice is great.  Keep it coming.

[Tracker0721]

I love all the knowledge and ideas that get tossed around and shared here. My idea is using steel you'd want the bone crushing KE. Using obsidian that doesn't really matter so the optimum speed to weight would be ideal then