Quote:
Originally Posted by Knotter
Many guys, including myself obsess(ed) about the bow we shoot and give only casual thought to the quality and integrity of the projectile. Too often the arrows and BHs get treated like an accessory. I have overheard some interesting conversations at the range/bow counter about how fast a bow is etc. For IBO speed the arrow they are using is effectively a soda straw with an aluminum insert and tiny field point. No talk of momentum, cutting performance, efficiency, bow noise.
Shooting proficiency is a whole other factor that is too often cited as a be all/end all response to arrow component selection. How many times have you seen a response like "put 'er where it counts and it don't matter"? What if the shooter freaks out and misses "where it counts"... That's where the killer arrow comes in to increase your odds a little.
Try this as a mental exercise... spend 20 minutes and develop the best/most lethal arrow you can and THEN worry about a bow that can shoot it well.
According to Ashby's studies. All other things things being equal :
1-cut on contact heads penetrate further than punch through style, and penetrate further on average than mechanicals (some fail to open). this equates to an immediate reduction of momentum.
2- tanto tips curl/bend/fail less often than other styles of tips... probably a reason why many millitary knives carry this profile.
3-a slick surface (arrow and BH) and reverse taper on an arrow penetrate further.
4 -Two blades penetrate further than 3 or 4.
5- Single bevel Broadheads continue to rotate after contact (it's only one factor). I wouldn't expect your best arrow to split the heavy part of a scapula no matter what. On marginal hits they do more damage than double bevels.
Now the other parts of the arrow....
6-Brass and steel inserts fail less often than aluminum inserts.
7 - EFOC arrows penetrate further than non EFOC. Something to do with less flex/oscillation. This is easier to do with heavy inserts.
8- Heavier arrows penetrate further... added benefit of possibly reducing bow noise ( a more efficient bow/arrow setup).
9- a thinner arrow penetrates further.
If each of these factors increase the results by even a few percent each it could be the difference between a hero shot and a sob story.
My $.02
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Very good information here but one little observation test is that some compound bows do not maximize momentum with a heavy arrow!..... because there is too much inertia to overcome out of the hole.... (comparison to type of prop on a boat) A high speed prop has more top speed but on a heavy boat it is not effective enough unless you pour the horsepower to it....
Now lets take a 60lb compound bow.... I have found that by figuring out where momentum is maximized with it may be with a 540 grain arrow but... because its initial speed is down it has a quicker drop....
When I look at the fact that arrow placement is most important I blalnce weight with trajectory and many people are shooting a hunting arrow between 380 and 450 grains....with a compound bow....
Momentum is a very simple measure it is velocity times mass.... however because KE is what bow produces and that amount of KE is fixed based on its draw weight and length. As the bow cycles this Energy is transferred into three types of KE, mechanical energy of the arrow, and sound/noise/vibration....and heat; efficiency is expressed as percentage of KE being transferred into work or mechanical energy....
Heavier arrows will make bow quieter as well adding to efficiency.... but the bow needs to overcome the inertia of the arrow.... think of an infinitely heavy arrow.... the bow cannot overcome that inertia....and there would be a rebound effect... (archer would collapse eventually) an infinitely light arrow and there is no mass to absorb the energy meaning 100% is being transferred into noise, vibration, and heat (a dry fire) and is damaging as well....
so again there is a balance, a heavy enough arrow to get the required penetration (once arrow has passed through extra penetration is a waste).... while having a reasonable trajectory....
BUT there is also a point where momentum is maximized on a bow and depending on the draw cycle.... Here is what happens with my old target bow...
2712 indoor target arrow = 720 grains x 180 fps = 129,600 units of momentum, (Bow is quiet)
2315 indoor target arrow with 180 grain tips = 540 grains x 245 fps = 132,300 units of momentum.... (Bow is quiet)
Medallion outdoor FITA arrow = 380 grains x 295 = 112,100 units of momentum (bow gets louder) flattest trajectory out to 90 meters.. (also most consistent at long distance)
3D Arrow... 310 grains x 315 fps = 97,650 units of momentum
(bow is very loud) but has very flat trajectory out to 50 yards
Now this is initial momentum only... how they retain speed or momentum down range and the resulting effect on trajectory is huge...
Now in a brand new test bow....
Going in reverse....
310 grain arrow = 340 fps = 105,400 units of momentum (bow is loud)
380 grain hunting arrow x 320 fps = 121,600 units of momentum (bow is quiet)
405 grain hunting arrow x 296 fps = 120,000 units of momentum... (bow is quiet)
540 grain arrow x 220 fps = 11900 units of momentum....
As one can see this bow is designed best for a 380 grain hunting arrow to maximize momentum, with the extreme hard cam and overdrive style eccentric it really has a hard time getting a heavy arrow out of the hole and going.... light arrow it can get going fast and then the overdrive at the end gives a little additional kick that really kicks the speed up.... the string speed on these bows are incredible and have been built from the ground up to maximize hunting arrow characteristics...
I know what started as 2 blades vs.3 got into this but the single biggest factor in creating drag as an arrow goes through an animal is surface area, dull blades have more surface area, 3 blades have more surface area....
then broadhead shape.... steep angled broadheads have a higher angle of incidence....and slow down faster but low angled broadheads have less angle of incidence thus penetrate further... BUT HAVE MORE SURFACE AREA... thus the balance again....
then blade thickness and cutting diameter... the wider the wound channel the less the penetration...
for me I use the broadhead for the job, for my 45 lb longbow I use low incidence, heavy broadheads, because momentum is maximized with heavy arrow with that bow and need to aid penetration... got pass through on a doe at 15 yards....
with my compound when I put a 75 grain muzzy MX-3 (380 grain arrow) THROUGH a moose at over 50 yards I probably could have added 3 more blades.... however I was glad for flat trajectory....
At the end of the day they all do the job, One final comment is that with higher speeds coming from a compound is that with a 3 blade broadhead it is self correcting in flight as the potential planing vectors cancel out....
with 2 blades there is a potential planning angle that will exaggerate improper tuning... i.e. arrow spine thus why spine is so critical especially with my trad setup....
I have personally taken many dozens of big game animals with two blade heads with compound... back in the day it was Bear Razorhead or NAP Razorback style heads...
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