Explaing some bow tests to me

[Stringslap16]

So I am looking to get a new high performance low cost hunting bow.  One of the bows I am considering is a Predator Bows Hunter Model recurve.  Found a couple bow reports online, and it seems that the Predator (50.5# at 28") shot 454 grain arrows an average of 193 fps with fingers.  While a way more expensive DAS Dalaa fired (53# at 28") 350 grain arrows an average of 189 fps with fingers.  The Kinetic energy of the arrow was basically the same.   So a few questions.  Why does the Dalaa get beat speed wise by another bow of lower poundage with an extra 100 grains on its arrows?  And since Predator fired the extra 100 grains 4 fps faster how is the KE the same??  Physics guys what am I missing here?  On a side note, barring accuracy which wasn't tested the Predator basically tied the Black Widow tested, very interesting.

The details:

Model:
 Predator "Classic"
   
 Bow Specs:
 
 Bow Length: 60 inches
 Draw Weight: 50.5 lbs @ 28 inches
 Recommended Brace Height: 7 1/4 inches - 7 3/4 inches
 Physical Weight: 2 lbs 12 oz
   
 Test Results at 28" draw length:
 
 Stored energy: 47.72 ft-lbs
 Stored energy per pound of draw weight: 0.95 ft-lbs/lbs
 Arrow weight: 454 grains
 Arrow Speed: 198 fps   with mechanical release
 Kinetic Energy of arrow: 39.53 ft-lbs
 Dynamic efficiency: 82.8 %   (kinetic energy / stored energy)
 Arrow Speed: 193 fps   with finger release


Model:
 Dalaa with 21" Riser
  Bow Specs:    
  Bow Length: 64 inches
  Recommended Brace Height:

 7 1/4 inches - 7 3/4 inches
  Materials:  
  Limb Materials (layers from back to face): glass, carbon, two layers of maple, carbon, glass  
  Riser Materials: aluminum with synthetic grip  
     
  Test Data:
   
  Physical Weight: 3 lbs 7 oz
  Brace Height for Testing: 7 3/8 inches
  Draw Weight: 53 lbs @ 28 inches (AMO)
  Stored energy: 48.89 ft-lbs
  Stored energy per pound of draw weight: 0.92 ft-lbs/lbs
  Arrow weight: 344 grains
  Arrow Speed with mechanical release: 194 fps    
  Kinetic Energy of arrow: 39.79 ft-lbs
  Dynamic efficiency: 81.4 %  (kinetic energy / stored energy)
  Arrow Speed with finger release: 189 fps

[Stringslap16]

So who is the idiot that typed Explaing instead of Explaining? That would be me, nice.

[Orion]

Somebody's math appears wrong, or there may be a typo in one or more of the numbers.  For example, the weight of the arrow shot by the DAS bow would be about 6 1/2 grains per pound or draw weight.  That's a lot less than most bows are tested at.  I believe most tests are done at 9 gpp for uniforminty across tests/bows. An arrow that is both slower and lighter doesn't produce the same amount of kinetic energy as the faster and heavier arrow.

[Stringslap16]

That's what I was thinking

[O.L. Adcock]

That looks like Blacky's data and theres obviously a misprint on the Dalaa arrow weight. He does all his tests at 9gr/lb or very close to it. The Dalaa arrow weight should be in the 470 range, not 344. The KE's listed are for the mechanical release also, not the fingers. Those wanting a KE calculator, this is a good one:  http://home.att.net/~sajackson/ke.html

...O.L.

[toddster]

Bow test to me is, the one that feels right in my hand and I can hit what I aim at!!!  All the math doesn't matter.

[O.L. Adcock]

Stringslap, This is the test you are looking at. Looks like Blacky's numbers are correct. Where did you get 344?  http://bowreports.com/recurve-bows/predator/review-eng.pdf

Toddster, you use a 20# bow for brown bears, I'm sure!   ....O.L.

[30coupe]

O.L.

344 is what Blacky posted

 http://www.bowreports.com/recurve-bows/daala/dalaa.htm

Still gotta believe it's a misprint though.

[NDTerminator]

I presume you are talking about the bow tests in TB Magazine.

I read them all too, and have come to the conclusion the only part I care about is the arrow speed with finger release.  These are always high due to the unrealistically light weight arrow used in this testing, and that the bows are not set up for hunting.

I have come to the no doubt heretical conclusion that a group of say, 60" 50# bows, shooting the same weight arrow drawn to 28", will almost without exception shoot within 10FPS of each other.  Doesn't matter if it's the least expensive Korean import or an Americam made production, or even most costly semi-production or custom.

These tests bear this out, as does my less scientific testing of shooting my own bows over my chronograph with various weight arrows.  Next to arrow weight, I have come to the conclusion a clean release has the greatest bearing on arrow speed.

So it comes down more to a perception and personal prference/pride of ownership type thing, more so than a performance issue (handshock & handling issues aside, as you won't discover them until you shoot the bow awhile).

Put another way and using extreme examples, if a #50 Korean import costing $240-$290 shoots say, 185 FPS, and a #50 semi-production costing $875 shoots maybe 190 or so, is it worth roughly $100 per each extra FPS to justify buying the more expensive bow?

Just some food for thought...

[Stringslap16]

has to be a typo...

yeah I want to get a purty custom someday, but right now I want the best performance I can get for my $$$

[O.L. Adcock]

Yep, just a typo.

NDT, "I have come to the no doubt heretical conclusion that a group of say, 60" 50# bows, shooting the same weight arrow drawn to 28", will almost without exception shoot within 10FPS of each other."

If you narrow it to 60" bows, maybe...What is 10fps? It's a good 45 pound bow performing as well as poor 50#...It's a good bow shooting as well at 26" as the other at 28"+. Lump "glass" bows in general and you'll find 20+ fps difference between them. Not a big deal if you can/are shooting more bow then you need. Folks like to recommend biginners "shoot as much draw weight as you can accurately"...Good advice...Why shoot a 60# bow and get 50# worth of performance out of it? The latter is as valid as the first...O.L.

[O.L. Adcock]

NDT, " #50 Korean import costing $240-$290 shoots say, 185 FPS, and a #50 semi-production costing $875 shoots maybe 190 or so,"

Yep, I can show you examples of $1000+ dollar recurves what won't out shoot those $300 over seas bows. Do you know which ones they are?...That's the reason for these tests.

"only part I care about is the arrow speed with finger release."

A bow thats 5fps faster then another off the machine will still be 5 fps faster with both shot with fingers. If a person understands that, both numbers are valid whether stated or not. The split stays constant whether drawn to 24" or 30" also.....O.L.

[NDTerminator]

I knew my opinion would be viewed as that of a heretic...

Of course O.L., I was referring to your stuff and a couple other makes/models when I stated "almost without exception" in my second paragraph.

However if you are going to quote me, at least use the entire sentence so as not to add spin.  For clarification here it is;

"Put another way and using extreme examples, if a #50 Korean import costing $240-$290 shoots say, 185 FPS, and a #50 semi-production costing $875 shoots maybe 190 or so, is it worth roughly $100 per each extra FPS to justify buying the more expensive bow?

Seems to have a different and very clear meaning when the entire thing is used, doesn't it?

The point is valid, whether you agree or like it.
If 5FPS faster is worth $500 more to a prospective buyer, then he has a helluva lot more money than me to throw around.  

As a purely practical matter, at 20 yards when hunting both will perform only as well as the shooter.  In my experience the deer don't know or care if they were arrowed with a $250 bow or the $875 model...

I fully agree that both the machine release and finger release numbers are valid, however until I hunt or do my shooting with a machine release, that data is at best interesting but not terribly useful...

[O.L. Adcock]

NTD, I wasn't including mine in the mix either...I know they are over priced and not being able to afford a custom bow on an enlisted man's pay is what got be started building bows to begin with. The price ratios sounds about right considering all our back door social programs. If I could find good workers for $100 a week, I too could crank out $300 bows! I just heard of another American arrow company sending it's production to China, and we wonder why?   ....O.L.