Bow Calculator

[gfugal]

You might try using a graphical solution at 10 x 10 squares per inch, and there are some online graphing apps around also.  But as you pointed out, the extra precision is needed with the data collection.

That might work but I don't think it would be as accurate. After more study, I'm thinking the method I'm using is as accurate as it can be. The limiting factor isn't finding the area but ensuring you have enough measurements. I included a picture to further explain what I'm doing.

In actuality, I think the challenge with bows, is not measuring the energy in or out, but rather identifying and rectifying the causes of the losses. Have you had a chance to look over some of Bakers essays, in addition to Koois?

I wholeheartedly agree. The thing is you don't know what losses your bow has without measuring the energy in and out. you can have pretty close ideas based on feel, or you can do the normal steps to eliminate it, but ultimately actually having a measurement can only help pinpoint those concerns. I just see it as a measurement telling you what you've got, just like we measure draw length, draw weight, flight distance, arrow speed or whatever. All those things technically don't need to be measured. I can get a feel for how far a bow is drawn, or a feel of how heavy it is, or a feel for how far/fast it shoots; it's just nice to have data to back up what I feel.

I haven't been able to read any of those essays. Will a google search pull them up?

as for some of the other spreadsheets, one can find the underlying formulas. it would be interesting to see if any adjust for the mass at each station along the limb.

It would be interesting to examine their formulas. I'm not a pro at excell though so I'll have to look up where to find them. For example Alan's sheet calulates numbers into a cell but when you click on the cell there is no formula so their hidden somewhere else. They account fro mass at other points so I would assume the do in their calculations.

[Badger]

You might try using a graphical solution at 10 x 10 squares per inch, and there are some online graphing apps around also.  But as you pointed out, the extra precision is needed with the data collection.

That might work but I don't think it would be as accurate. After more study, I'm thinking the method I'm using is as accurate as it can be. The limiting factor isn't finding the area but ensuring you have enough measurements. I included a picture to further explain what I'm doing.

In actuality, I think the challenge with bows, is not measuring the energy in or out, but rather identifying and rectifying the causes of the losses. Have you had a chance to look over some of Bakers essays, in addition to Koois?

I wholeheartedly agree. The thing is you don't know what losses your bow has without measuring the energy in and out. you can have pretty close ideas based on feel, or you can do the normal steps to eliminate it, but ultimately actually having a measurement can only help pinpoint those concerns. I just see it as a measurement telling you what you've got, just like we measure draw length, draw weight, flight distance, arrow speed or whatever. All those things technically don't need to be measured. I can get a feel for how far a bow is drawn, or a feel of how heavy it is, or a feel for how far/fast it shoots; it's just nice to have data to back up what I feel.

I haven't been able to read any of those essays. Will a google search pull them up?

as for some of the other spreadsheets, one can find the underlying formulas. it would be interesting to see if any adjust for the mass at each station along the limb.

It would be interesting to examine their formulas. I'm not a pro at excell though so I'll have to look up where to find them. For example Alan's sheet calulates numbers into a cell but when you click on the cell there is no formula so their hidden somewhere else. They account fro mass at other points so I would assume the do in their calculations.

   We usually figure that our losses come from vibration and hysterisis. The vibration losses can be attibuted to several things. Heavy outer limbs have more momentum as the move forward and the weight of the arrow is not always enough to keep them under control. This cause some amount of distorsion in the limbs where all the power is not going into the arrow. It can be difficult to isolate where exactly the losses are comming form. It can be done but I think it is too much work to do it manually.
   My favorite methos I used only one time, I used extremely heavy arrows to the point where the virtual mass was only about 7% of the arrow weight. I then progressively used lighter arrows. I was able to extrapolate out a pattern that I felt allowed me to seperate the hysterisis from vibrations with reasonable accuracy.

[willie]

That might work but I don't think it would be as accurate.

I'm gonna  bet that you grew up in the computer age, and you do know, that you are asking questions to a lot of old timers here?  Actually you might be surprised that quite a few of the worlds engineering feats were accomplished with not much more than graphical solutions, and we sent men to the moon in the days of the slide rule.....

Ok, I will stop ranting, and move on.  The essays that come to mind were published primarily in TBB series.  Bow Design and Performance in the 1st, and Design and Performance Revisited in the 4th. You can find quite a bit of his Tims work (and more) discussed in the archives at Paleoplanet, along with helpful info about some of the spreadsheets discussed earlier.
 
Actually google can help searching the forums, as it often returns better results than the forums own search  feature.    something like         hysteresis site: http://www.primitivearcher.com
   
or                                                           spreadsheet  site:http://paleoplanet69529.yuku.com

browsing thru all of a selected authors posts works even better


try rows above and below row 100 on woodbears sheet