Kinetic energy---- got my eyes opened!!

[ron w]

I had a 55# @ 28" Bear recurve [Kodiak Hunter] that I shot thru a chrony years ago. I shot shot 4 shots with 2216 shafts 30 1/2 long 125 gr up front. I draw just over 29". 4 shots were 170-173 fps. I did it again and it was the same. I would feel confident shooting that set up at anything I would ever hunt anywhere,any place! I think the arrows were around 575 GR.

[RC]

I would`nt sweat it. My set-up a 47@27 Mohawk with a 570 grain arrow shoots maybe 160. I shoot the broadhead through most every critter I shoot and I usually shoot Big broadheads.
  When I shot the bow through the chrono the fellas at the "pro" shop were snickering a little in fun till we started talking about how "many" dead critters. The icing on the cake was when I showed them a judo point and told them I set my sights while I hunted.RC

[Kentucky Jeff]

When I was shooting long range highpower rifle I learned why velocity is less important than mass (bullet weight).

Mass is the only part of the equation that doesn't change.  All things being equal a light projectile will loose velocity faster than a heavy projectile.  When you talk bullets a slow 190 grain .308 bullet at say 2650 fps will outperform a fast 155 grain bullet at say 3050 fps at 1000 yards.  Because its not the muzzle velocity that matters but the retained velocity.  

The bullet isn't affected by the wind at the muzzle nearly as much as when its 1,000 yards downrange.  And a 190 grain bullet will be going faster than the 155 at 1,000 even though it started off slower.  Not only does it beat the lighter bullet for velocity but its also heavier and therefore harder for the wind to blow than the lighter bullet.  I've shot too many 1,000 yard matches and have proved this to my satisfaction many times over.  The guys who worshipped at the alter of speed and shot light bullets consistently got their clocks cleaned by guys who shot big slow bullets at long range.  Before someone chimes in and tells me the Palma load is 155 grains I'll let you know that that's a product of the Palma rules and the bullet cannot weigh more than 10 grams.  Trust me, they'd be shooting 175-190 grain bullets if the rules allowed.

So how's all this apply to arrows.  Well, think about it.  First, the observation that kinetic energy is a poor predictor of arrow performance is spot on.  There are a ton of factors that diminish the kinetic energy of an arrow.  Heat for example...as the arrow goes through flesh the friction from the blade and shaft passing through the animal generates heat.  Not much I know....  But that heat is energy from the arrow and detracts from the ability of the arrow to do meaningful work.  There are a ton of other factors as well.  But the point is that velocity is less important with most trad arrow performance than arrow mass.  Obviously this isn't a linear equation.  At some point in the curve velocity becomes important.  But the mass doesn't change.

[stujay]

550 gr arrows 165-170 fps, sounds bout right to me.
Questions: is it quiet?, Is it smooth? Is it balanced and not too heavy or too light? Does it hit where you look and are you pleased with its feel in the draw and after release? If your answers are yes, you've got a winner in my book.

[JParanee]

Macksdad

I was surprised at how slow my Buff was also

Really nice shooting bow but not a speed demon

It even likes a longer hence softer arrow than my other like set ups

From what I have been told by Bowyers like Fedora is that colder makes for faster

I am getting around 175 with a  530 grain arrow out of a 55 pound at 28 inch Buff

It still scales around  54 pounds for me

Maybe your chrono is off try another

[JParanee]

Sorry double post

[jax]

I don't think it really matters unless you are into physics.

[gonefishing600]

Originally posted by Kentucky Jeff:
So how's all this apply to arrows.  Well, think about it.  First, the observation that kinetic energy is a poor predictor of arrow performance is spot on.  There are a ton of factors that diminish the kinetic energy of an arrow.  Heat for example...as the arrow goes through flesh the friction from the blade and shaft passing through the animal generates heat.  Not much I know....  But that heat is energy from the arrow and detracts from the ability of the arrow to do meaningful work.  There are a ton of other factors as well.  But the point is that velocity is less important with most trad arrow performance than arrow mass.  Obviously this isn't a linear equation.  At some point in the curve velocity becomes important.  But the mass doesn't change.

Ok, work with with me a little here!!

Mass and speed are the two main components of kinetic energy.

Let’s say you came home and your wife had cut all of your bows in half, so you decided to end your life by stepping out in front of on coming traffic. I don't know about you, but for me, I would want to pick the biggest and fastest semi-truck I could find, lots of kinetic energy here, I'm talking massive. Forget about the small economy cars.

So what has this to do with arrows? Big and fast = more killing power. I didn’t say light and fast!

So does it really matter, I think it does. If we compare apples with apples, such as; Same draw weight, different limb materials, same arrow weight, and then measure the speed of that arrow, and calculate the kinetic energy, we are then able to make a more informed decision about the bows we want to purchase.

For example,  if you where comparing two bows of different draw weights, and the lighter bow could produce the same kinetic energy as the heavier bow shooting the same arrow, which bow would you choose? Or, if you knew a particular material would produce more kinetic energy, wouldn't that narrow your search?

Iron sharping iron!

[Blacky]

Macksdad,

there's something wrong with your measuring equipment, since an arrow weight reduction of 120 grains only gave you 10 fps more speed.

This reduction should have given you close to 30 fps more speed. FWIW

Blacky

[macksdad]

My chrono is brand new, however in todays world that doesn't mean much I am sure it could definitly be faulty. How do I check it,  only way I know would be to shoot something with a known speed through it. Like a rifle that I know the muzzle velocity of or put it side by side with another chrono.

[hybridbow hunter]

Originally posted by Blacky:
Macksdad,

there's something wrong with your measuring equipment, since an arrow weight reduction of 120 grains only gave you 10 fps more speed.

This reduction should have given you close to 30 fps more speed. FWIW

Blacky

No Blacky, thats sounds correct.
10 gr add weight is close to 1 fps loss of speed for trad gear. The speed loss you mention is what happen more likely with compound bows (10 fps for 30 gr)

[Pinelander]

I've chronographed a lot of bows. Most good bows will shoot a 9 gpp arrow at 180 fps with finger release and 28" draw.

Your Buffalo is shooting a 7.6 gpp arrow at 180 fps with a 29" draw?

The bow is slow, or the chronograph is way off. Probably the latter.

- Dave

[MCNSC]

I learned this the hard way. If you are happy with your bow don't shoot it thru a chrono.  

[Blacky]

I beg to differ hybridbow hunter. I test trad bows since 1996 with a shooting machine and have done extensive testing with different arrows. It takes 3 - 6 grains of weight to gain or lose 1 fps in speed. At least thats my finding with over 100 different longbows and recurve bows tested.    

Blacky

[MCS]

How far would you stand from the crony when testing?

[Troy Breeding]

I look at it as stated earlier. If your happy with you bow stay away from the chrony. I seen several bows damaged just so the shooter could say my bow is the fastest.

Troy

[L82HUNT]

My chrono just said my Centaur Carbon Elite shot a 420 grain arrow at 50@27" my draw, at 171 fps.  Im pretty sure its off.

[macksdad]

MCS, I was standing at various distances from 5 ft to 20 ft. ,and I am very happy with the performance of my bow. I was just curious as to the real numbers of its performance. I dont plan on changing my setup at all. Just was surprised at the numbers.

[hybridbow hunter]

Blacky,
with respect 2 to 3 fps variation for 10 gr is too much.
i and few other friends on the french traditional archery hunting forum also tested most of bows of north american brands and bowyers products. We do our testing under strict protocol using shooting machine, accurate bow weighting for draw force curve. Bows are tested all with astroflight 12 strand pre stretched string custom made for each bows and bows are tested ready-to-hunt with average brace height (according to the bowyer) and same string silencers put at 1/4 of string length . Our test are devoted to give the performance that "Average Joe" will get from the bow in real life conditions for hunting from 8 gpi to 14 gpp. Our tested bows are the bows we purchase as customers,( most of all are in the 48-53# @ 28" range),  so there is no commercial bias nor "specially-made-for-test bows".
If you look to the following graphs of several different , but fairly known, bows and brand you will see that whatever the bow design or level of performance for a given design, 10 gr leads to approximately 1 to 1,5 fps variation for 100+ gr weight modification
As exemple here you can see very fast hybrid (ACS), fairly fast hybrid (Fedora xtrem), fairly fast recurve (RER)  and low average speed recurve (BW PSA)
All graphs are done by one of us, engineer and physics university professor. Him and i, as a neurosurgeon, are really concerned about accuracy and rigorous scientific approach when doing this (as hobby  LOL)
Regards
Laurent


For each bow (BLUE LINE= speed) 1st Graphs is arrow speed/arrow weight in grain and 2nd Graph is arrow speed/ arrow speed in gpp

(GREEN LINE is "rendement"=dynamic efficiency )
(RED LINE is "energie cinetique"=kinetic energy)


             
           

             
           

             
         


             
           

[ishoot4thrills]

hybridbow hunter, impressive stats. Difficult to follow, but impressive.        

Blacky(R. Blacky Schwarz) is the dude who does all the bow testing for Traditional Bowhunter magazine. I'm pretty confident in his results/experience.

Maybe your testing parameters are somewhat different, resulting in different results.    

In my opinion, the difference isn't worth argument.