Author Topic: how much faster is a recurve than a strait tip bow?  (Read 19157 times)

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Offline George Tsoukalas

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Re: how much faster is a recurve than a strait tip bow?
« Reply #90 on: April 28, 2017, 02:53:34 pm »
Brad, very impressive. Jawge
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Offline bradsmith2010

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Re: how much faster is a recurve than a strait tip bow?
« Reply #91 on: April 28, 2017, 03:33:33 pm »
thanks Jawge, I just got lucky on that piece of wood,, but have always felt the straigt tip bow was underated,,, this discussion has brought to light alot of interesting views, and I am less confused at this point,, and feel that the recurves can be faster,, but not as much as some had indicated in the past,, I think some of the conclusions have been very realistic,, (-S

Offline Stick Bender

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Re: how much faster is a recurve than a strait tip bow?
« Reply #92 on: April 28, 2017, 04:50:41 pm »
 This is a very interesting topic hope it keeps going but common sense tells me at a Certain length there is probably diminishing return recurving and if you have a strait limb bow at the lightest durable mass and recurve it & takes additional set it probably is going to be a slower bow then if just left strait but there is so many dynamics at play on this topic ,length,self bow, sinew, composite,bendy vs handled bow, etc it's hard to compare apples to apples 
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Offline sleek

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Re: how much faster is a recurve than a strait tip bow?
« Reply #93 on: April 28, 2017, 06:46:31 pm »
But they do so with less leverage
Hence recurves. Its the best of both worlds. You get the leverage and good string angle of a longer bow from the recurves/"levers" but also shorter limbs so they can rotate quicker when they snap back to brace.
I've been considering that since i typed my reply. I have almost run out of arguments for my initial view point and am leaning towards recurves having an advantage.
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Offline upstatenybowyer

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Re: how much faster is a recurve than a strait tip bow?
« Reply #94 on: April 28, 2017, 07:32:13 pm »
This thread puts me in the mood to build a recurve.  (-P )W(  :BB   (SH)  :G
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Offline bradsmith2010

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Re: how much faster is a recurve than a strait tip bow?
« Reply #95 on: April 28, 2017, 08:23:00 pm »
Sleek I like it that you can outthink your self,, very postivie,  :BB

Offline sleek

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Re: how much faster is a recurve than a strait tip bow?
« Reply #96 on: April 29, 2017, 02:37:06 am »
Just putting puzzle pieces together. I may not have all of the pieces, but with enough, i can rekcon what the rest are.
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Offline sleek

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Re: how much faster is a recurve than a strait tip bow?
« Reply #97 on: April 29, 2017, 03:54:28 am »

WARNING. THIS POST MAY CONTAIN TRACES OF NUTS

If you get leverage and reduced string angles from recjrves, I can assume only they are because of each other. Leverage is a function of string angle.

If I take this and run with it,  then the lower the string angle the more leverage I have. This creates in my mind a recurve that at full draw never has the string leave it. My mind instantly compares two recurves, one with large radius, the other small. The string angle stays the same no mater the radius as the bow is drawn. So now my mind favors small sharp hooks for weight reduction.

To carry this though further, my mind visualizes a recurve fashioned so the string just begines to come off the end of the recurve once full draw is hit. Any more wood in the recurve beyond where the string just comes off is waisted weight. 

I now compare bow lengths. To keep the string on a short bows recurves you may need hooks that are 90 degrees. But if you lengthen the bow a certain amount, you could get away with 30 degree hooks and still keep the string on the recurves to that last inch of draw. That allows you to take advantage of the longer bows advantage of having a naturally lower string angle even without recurves.

I imagine in my mind a small recurve the radius of a golf ball vs one the radius of a bowling ball. The amount of string that comes into draw as the bow is drawn is much less on the golf ball sized recurve, forcing tje limb into more bending and stress. The bowling ball recurve lets off more string as the bow is drawn stressing the limb less because less bend is needed to reach full draw because more string is coming into the draw.  To allow myself to elaborate and be more clear, its a distance/circumference thing. The larger the radius the longer the string is that sits on it etc...

What advantages could be had with either situation? Well, the larger recurve is less stressed so the limbs can be mkre narrow to allow less limb mass. Also, the bending could be more focused towards the fades allowing for less bending limb and less vibration losses. The tighter radius would require a longer working section of limb to handle the fact that it is more stressed. This would allow it to have more losses due to vibration.  However tip mass does come into play as well with the obvious benefits.

I draw the conclusion now that a shorter bow with larger diameter recurves is the best bet. Seems the best of all worlds. Large radius recurves reduce how much beding is needed, keep the recurves narrow enough to reduce weight and remain stable. The shorter limbs will be less stressed and have less vibration, allowing for thicker wider limbs to fo the work. Ideally,  if a bow could be so designed, it would bend only out the fade then go straight to large static recurves. Keeping in mind as well, we want to keep the effective length of the bow as short as possible  to take advantage of the fact objects spin faster in tight arcs such as the arc formed as the tips come around to full draw.

Of course, i reserve the right to be wrong.
« Last Edit: April 29, 2017, 04:03:54 am by sleek »
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Offline Marc St Louis

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Re: how much faster is a recurve than a strait tip bow?
« Reply #98 on: April 29, 2017, 08:22:05 am »

WARNING. THIS POST MAY CONTAIN TRACES OF NUTS

If you get leverage and reduced string angles from recjrves, I can assume only they are because of each other. Leverage is a function of string angle.

If I take this and run with it,  then the lower the string angle the more leverage I have. This creates in my mind a recurve that at full draw never has the string leave it. My mind instantly compares two recurves, one with large radius, the other small. The string angle stays the same no mater the radius as the bow is drawn. So now my mind favors small sharp hooks for weight reduction.

To carry this though further, my mind visualizes a recurve fashioned so the string just begines to come off the end of the recurve once full draw is hit. Any more wood in the recurve beyond where the string just comes off is waisted weight. 

I now compare bow lengths. To keep the string on a short bows recurves you may need hooks that are 90 degrees. But if you lengthen the bow a certain amount, you could get away with 30 degree hooks and still keep the string on the recurves to that last inch of draw. That allows you to take advantage of the longer bows advantage of having a naturally lower string angle even without recurves.

I imagine in my mind a small recurve the radius of a golf ball vs one the radius of a bowling ball. The amount of string that comes into draw as the bow is drawn is much less on the golf ball sized recurve, forcing tje limb into more bending and stress. The bowling ball recurve lets off more string as the bow is drawn stressing the limb less because less bend is needed to reach full draw because more string is coming into the draw.  To allow myself to elaborate and be more clear, its a distance/circumference thing. The larger the radius the longer the string is that sits on it etc...

What advantages could be had with either situation? Well, the larger recurve is less stressed so the limbs can be mkre narrow to allow less limb mass. Also, the bending could be more focused towards the fades allowing for less bending limb and less vibration losses. The tighter radius would require a longer working section of limb to handle the fact that it is more stressed. This would allow it to have more losses due to vibration.  However tip mass does come into play as well with the obvious benefits.

I draw the conclusion now that a shorter bow with larger diameter recurves is the best bet. Seems the best of all worlds. Large radius recurves reduce how much beding is needed, keep the recurves narrow enough to reduce weight and remain stable. The shorter limbs will be less stressed and have less vibration, allowing for thicker wider limbs to fo the work. Ideally,  if a bow could be so designed, it would bend only out the fade then go straight to large static recurves. Keeping in mind as well, we want to keep the effective length of the bow as short as possible  to take advantage of the fact objects spin faster in tight arcs such as the arc formed as the tips come around to full draw.

Of course, i reserve the right to be wrong.

Could be you think too much  :OK
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Offline sleek

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Re: how much faster is a recurve than a strait tip bow?
« Reply #99 on: April 29, 2017, 12:21:56 pm »
How else am I supposed to do anything that mimics intelligence?
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Offline bradsmith2010

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Re: how much faster is a recurve than a strait tip bow?
« Reply #100 on: April 29, 2017, 12:37:53 pm »
a strait tip bow so relaxing,,  (SH)

Offline Badger

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Re: how much faster is a recurve than a strait tip bow?
« Reply #101 on: April 29, 2017, 01:18:52 pm »
  Sleek, I htink you have a pretty decent concept except for one thing. A bow with big recurves reduces leverage at brace so it pulls harder. As it starts to lift off it gradually starts returning leverage and at the end still maintains lower string angles which increases leverage. This basicaly gives you a smaller difference between starting pull weight and final pull weight. Adding up to more stored energy. So take away leverage at the begaining and slowly give it back.

Offline sleek

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Re: how much faster is a recurve than a strait tip bow?
« Reply #102 on: April 29, 2017, 01:30:13 pm »
Would that mean there is a better shape for a recurve other than round to take full advantage of that concept? An elliptical shape recurve for example? Or more like, one that gets a tighter radius closer to the tip, visualize an elf shoe tip. The curve starts off large and tightens up as it goes... curly cue
« Last Edit: April 29, 2017, 01:33:21 pm by sleek »
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Offline bradsmith2010

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Re: how much faster is a recurve than a strait tip bow?
« Reply #103 on: April 29, 2017, 01:39:45 pm »
you guys are hurting my head,, but in a good way :BB

Offline Marc St Louis

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Re: how much faster is a recurve than a strait tip bow?
« Reply #104 on: April 29, 2017, 01:46:39 pm »
If there is an optimum shape of the recurves themselves then I have never found it.  I have tried large curves and small ones and found that there is no difference in performance between the 2; in fact I would suspect that the small curves would be better for flight shooting due to their lighter mass.  The one major difference I have found is that smaller recurves are less prone to introducing twist in the limb
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