Arrow weight vs force draw curve

[Selfbowman]

So I don’t high Jack the other thread I’ll ask question here. I’ve noticed that shooting to light a  flight arrow I guess that drag  takes over and the arrow just dies as it comes out of the bow. If to heavy I guess gravity takes over. So by doing your math thing with numbers in your  force draw some how compute the ideal mass or arrow weight. And yes I know mass placement is huge in the arrow.

[Del the cat]

Not sure you can calculate it directly, or from the force/draw curve.
But by plotting arrow speed vs arrow mass for a selection of arrow weights you hopefully you'd be able to see the point at which going lighter doesn't pay off in terms of the energy the arrow is carrying. Mind that's another can of worms... do we need arrow momentum (mass x velocity) or kinetic energy 1/2 m x v squared.
This post shows from my blog what I mean.
Del
https://bowyersdiary.blogspot.com/2011/11/mass-velocity-and-energy.html

[mmattockx]

Arvin,

What you are asking is not just about arrow mass, it involves the aerodynamics of the projectile as well. To incorporate bow dynamics, arrow dynamics on release and the aerodynamic performance of the arrow all into one model is a massive project that would be equivalent to the research required for several PhD theses.

The one way I can think of to directly measure arrow performance in flight is using doppler radar to track the arrow in flight and measure/calculate its velocity along the flight path. This is how some bullet companies do research on bullet shapes and calculate the ballistic coefficients for their bullets. The problem there is gaining access to those facilities and if the systems they use will work properly with arrows instead of bullets.


Mark

[Selfbowman]

Thanks guys. The math went over my head but I sort of understood your explanation. So far I’ve just been going on arrow weight that has previously broke records. Arrow dynamics’s also plays a huge part along with spine. I’ve got some flight arrows of days gone by. We haven’t improved on there design much at all. These arrows are from the fifty’s I think.

[willie]

Arvin,

a massive project that would be equivalent to the research required for several PhD theses.

I think Mark is accurate about developing computations....
But perhaps there is a way to experiment with what you have to get useful info..

if one assumes an arrow dies fast because of excessive velocity loss before the arrow settles into stable flight, then observing initial velocity out of the bow and the velocity at some shorter range rather (than shooting for distance), might be a way to find which arrows work best out of your bows with your releases.

What is the longest shot you could take at your shop if you set up a range?
What kind of group can you shoot at that range?

[bassman211]

The Turks way back when, tapered there flight arrows both ends to the middle, with tiny fletching, and shot arrows in the 220 to 250 gr. range as I understand it, They used over draws in some cases on there bows, and would heat there bows before shooting for distance in some cases. Some recorded distances they shot were not in the realm of reality in my mind. I still can't conceive it in my mind, and have no clue of the math, and physics involved.

[Muskyman]

I really don’t have anything to add to this conversation but, I started wondering what the heck is force draw curve. Looked it up and how to calculate it and now I’m going to have to calculate it on one of my bows.    Well maybe I am.

[Mo_coon-catcher]

What you need is two chronographs. A shoot through for up close and a Labradar style so you can measure velocity at the bow and set the other up for 100yards out. For your purpose you can just run with the given numbers to find out the rate of velocity drop per distance or can use the numbers to calculate the ballistic coefficient. This is how the average rifleman calculates the bullets BC from a specific barrel as it almost always varies from manufacturers given number. I think there are more radar style chronographs than Labradar but they were the first commercial one. I also recommend the Caldwell G2 geography for a shoot through. I rarely have reading errors and tested with a magneto speed chronograph with a rifle, it’s dead on with its readings.

Kyle

[Mo_coon-catcher]

I just did a quick read on the Labrador and it already tracks velocities every 5 yards or so out to 100 yards, or however far you have to shoot. So would be great data for flight shooting and you wouldn’t need a shoot through chronograph too unless you want it for velocity verification. But it’s not cheap and requires an extra accessories to work with arrows.

Kyle

[mmattockx]

I think there are more radar style chronographs than Labradar but they were the first commercial one.

The Garmin is currently the hot one to have. A buddy has one and it is very slick. Easy set up, does a bunch of the math for you on standard deviation and other statistical measures. I don't know if it tracks velocity over multiple ranges like the LabRadar does.

https://www.garmin.com/en-CA/p/771164


Mark