Force draw curve data?

[Eric Garza]

I have a theory I want to explore, but to do it I need data. Specifically, I need data on the force draw curves of wood bows of various sorts. I have data from a few bows that I have made, but that is not enough. I am particularly interested in getting force draw data from longer bows, including straight-stave bows, reflexed bows, and deflex-reflexed bows. Anyone willing to collect data from bows they have lying around and send it my way? Or send along data they already have?

[lleroy]

you might want to try out this: https://www.virtualbow.org/
can simulate force/draw curves on any bow design you can think of building.
takes a lot less time than actually making each bow :-)

[Eric Garza]

Thanks, but I want data from actual bows, not from a computer simulation. I spent years developing simulation models like the one you linked to, and as a consequence do not trust them much anymore.

[Marc St Louis]

There is some data here

http://www.primitivearcher.com/smf/index.php/topic,5717.0.html

[Eric Garza]

Thanks! I will search for other force draw curves and hope to find a few more posts like this.

[Lefty38-55]

Like what DETAILS? Pound reading at each inch of draw? Beginning at what draw or pull length? I have 2 self bows I can test/measure.

Hopefully you or the data can confirm, support or modify the oft-quoted dictum that a “well made self-bow should give a minimum bow speed in FPS of (100 + the bow pull weight at the rated draw length)”.

[Eric Garza]

I am less interested in the speed of the bows than in the shape of the force-draw curve. I am particularly looking at what different side-view profiles do to the inflection point between the initial energy storage and the start of the upwards curve where bows start to 'stack'. I will post results when they are ready.

[DC]

I have a bunch of graphs but unfortunately I can't relate them to bow shape any more. Just the graph wouldn't be much use I guess.

[Eric Garza]

Yeah, if you cannot tell me side-view profile to go along with each graph, that will not be helpful.

[PatM]

Maybe you could figure out  shape based on the data?  That would be a good test too. 

[Badger]

I am less interested in the speed of the bows than in the shape of the force-draw curve. I am particularly looking at what different side-view profiles do to the inflection point between the initial energy storage and the start of the upwards curve where bows start to 'stack'. I will post results when they are ready.

      That is a defective formula of very little use. It was based on all weight bow shooting at 500 grain Arrow.

[Eric Garza]

Steve, what formula are you referring to? I am not following you.

[TimBo]

I think he was referring to “a well made self-bow should give a minimum bow speed in FPS of (100 + the bow pull weight at the rated draw length)”.

[Del the cat]

The FD curve of every ELB and warbow I've made has been remarkably linear.
https://bowyersdiary.blogspot.com/search?q=FD+curve
Del

[willie]

 a fixture I built a while back could just as well be used to plot fd curves. Different limbs could be easily mounted to compare. adjustable for deflex or reflex and riser lengths.

http://www.primitivearcher.com/smf/index.php/topic,62820.0.html