Recurve Question

[SAM E. STEPHENS]

Say you have two recurves that are the same in every way , make , woods , ect. But one is 50#@28 and the other is 50#@30.The one is shot at 28in and the other is shot at 30in.What is the gain with the extra 2in in draw , how much is gained with the extra power stroke of the 2in with everything else being the same ( also same weight arrow ) I know the arrow wont be same spine with the two bows so we will say same weight arrow.And this can be two bows at any weight just one at 28in and the other at 30in ,or the question could be what is the gain per inch of draw past 28in in a bow of the same make 60#@28 , 60#@29 , 60#@30 , 60#@31 ,ect. I have been asked this many times cause I shoot a 30in draw.And I dont know the right answer , or is an answer not there to be had.Some bows are better than others and a 50# bow by maker xxx is as fast as a 55# by maker yyy. I dont know I just always say its a little faster and hits abit harder cause the extra powerstroke.Not that I give a rats butt about speed but I do care about a nice heavy arrow busten critters....
,,,,,,,Sam,,,,,

[FerretWYO]

Two inches of draw makes a pretty big difference. Even a 1/2 in can make a noticable difference in performance Speed being the key factor. The arrows will be flatter and hit harder the more time they spend on the string.

[crazymoose]

Just a note for every inch in draw length you gain approximately 2.5 lbs per inch.
So that being said a 50# bow at 28 inches drawn to 30 inches now becomes 55 lbs give or take.
As mentioned by FerretWYO even a 1/2 inch can make a difference.

[khardrunner]

crazymoose, I don't think that is what he is asking. He has narrowed it down to a difference in draw length alone. His examples were:

50@28 and 50@30

So, the gain in poundage between the 2 draw lengths is negligible. The key here is how much does "string time" effect the arrow speed.

[FerretWYO]

Originally posted by crazymoose:
Just a note for every inch in draw length you gain approximately 2.5 lbs per inch.
So that being said a 50# bow at 28 inches drawn to 30 inches now becomes 55 lbs give or take.
As mentioned by FerretWYO even a 1/2 inch can make a difference.

As mentioned he was asking about two bows same weight at different draw lengths for this situation.

[tradhunter]

The longer draw , even at the same # will be faster all things els being equal....the extra 2 inches is worth several pounds against the shorter length. It is the same weight,however more work is being done in the longer draw.

[SAM E. STEPHENS]

We are on the right track , Is a 50#@30 like a say 55#@28 Same type bow same arrow weight ect...
???????????

[3arrows]

15 to 20 fps.

[Archie]

Isn't there some Dr. Somebody out there who can give reliable info on this?  That longer power stroke has got to be measurable.  Why doesn't some bowyyer with a Hooter Shooter -- and a few bows to cycle through -- take an afternoon and do some testing?  Black Widow?  ACS?  Bigfoot bows?  

I've been waiting for an answer on this for a long time.  Sounds like a GREAT article for TBM, too.

[wingnut]

typically you gain 4-5 fps with each inch of draw.  So this should yield 8-10 fps gain in the 30" over the 28".

Mike

[Orion]

Even when the poundage is held constant, Mike?  I agree you would get that gain if the poundage increased from 28 to 30 inches, but he's saying the bow weight is the same 50#@28 vs 50#@30.

[FerretWYO]

Originally posted by Orion:
Even when the poundage is held constant, Mike?  I agree you would get that gain if the poundage increased from 28 to 30 inches, but he's saying the bow weight is the same 50#@28 vs 50#@30.

Yes even with the weight constant.

[wingnut]

Yes because you draw two more inches the area under the draw curve increases (stored energy, Efficiency stays the same, so the speed increases.

That's why I can shoot 50 @ 30.5 for moose.  Well that and the ACS-RC limbs. . .LOL

Mike

[Over&Under]

I agree with Mike and Randy...

All things equal - bow wood, length, type, arrow etc...if you are HOLDING 50 lbs when you draw the first bow to 28" and you are HOLDING 50 lbs when you draw the second bow to 30" - the bow drawn to 30"(even though the draw weight is the same) will have better performance because of what Mr. Westvang said...Its all about the draw curve and the stored energy...

[CoilSpring]

Sam,
In your example, you gain 10% stored energy behind that arrow when you draw the 50#@30" bow.

Archie,
I'm no Dr., but I have been blessed with a "graph-making" mind.          And, I like purdy pictures & crayons, so I made a few assumptions to help explain the 10% increase in stored energy.

   

Caution...this is what happens when you're "batching it" for the weekend.

But seriously...as said above...the bowyers on this site know their bows and can give you their bows' numbers off the top of their heads.  They are the true Tx.D's, Doctors of Toxophilia.        

[dragonheart]

Originally posted by wingnut:
typically you gain 4-5 fps with each inch of draw.  So this should yield 8-10 fps gain in the 30" over the 28".

Mike

Ditto, been my experience.

[Sixby]

I would think you would not gain over a couple of fps at the most when all other things are perfectly equal except the draw length. I would say 2 fps per inch would be max./ I bet
Bob Morrison knows . Trouble with most of us is haveing two bows that really are exactly the same in every respect except poundage to check./ You would definately have to have two foam core limbs to really find this out so that core tensil strength did not enter into the equasion.
God bless you all, Steve