Odd question - Son's Science Project

[Sharpsshooter]

I have a question relative to draw length and arrow speed that has little to do with practical archery.

In our house we are always looking for new ideas for science fair projects for the kids and my son wanted to do one for archery.  The idea is to test the theory that a recurve bow will shoot arrows faster than a longbow of equal weight, all things being equal.

I have two bows, a 35# Bear Grizzly and a 45# Neet Navajo.  I took the Navajo and measured the weight at various draw lengths and marked it at 35, 40 and 45 pounds.  I then took and shot the bows, the Bear at full draw and the Neet at 35, 40 and 45 pounds.  The draw length was 24, 26 and 28 inches respectively.  

My question is this:

Does draw length, at the same weight, affect the arrow speed at all?

TIA

If anyone is curious, I can post the results of his experiment.

[Bjorn]

As I recall 50@32 will be faster than 50@28 because the power stroke is greater for the longer draw length. But I don't think you are going to see differences at the shorter draw lengths for equal weights because the power stroke has not kicked in. Not an easy thing to test because the arrow weights and # for a given drawlength will be critical.

[Sharpsshooter]

Thank you for the reply.  I thought that there might be some difference, but I wasn't sure how much.  I think, for the purposes of a 4th grade science project, I will not worry about the draw length.

At the same draw length, shooting a 29" 2016 XX75 arrow with a 75 grain field point, the 35# @ 28" recurve comes in around 145 fps and the 45# @ 28" longbow is about 156 fps.  The longbow at 35# 24" is about 126 fps.

[Mark C.]

My son and I did a science fair project last year. It was a simple concept, all things being equal...we shot at different angles and measured the distance.....of each angle to distance. If you like this idea and your son waits till the last minute, and then you do 90% of the work..........I gaurantee a solid "C+"  

Mark,

 

 

[Bjorn]

Neat project and thanks for reminding me why I moved to California!

[ChuckC]

I am thinking that it is not as easy as that.  A lot of things can effect speed and delivery of an arrow and if you are comparing two bows, their own efficiency may have more to do with the delivered speed than anything else.
ChuckC

[Dave Worden]

My guess is, yes, the longer the draw length, the more energy imparted to the arrow, everything else being the same.  I have no idea if the amount of energy difference could be reliably measured in a simple experiment.