Originally Posted by
bigcountry
I asked you specifically if you had a bolt and arrow wieghing the same with the same drag, same fletch would the bolt loose KE and speed faster. You said yes. Remember. You then said there is no way both could have the same drag. This is correct, if that was the case, a set of arrows would all loose energy different.
Ok, lets start there. Do you agree with these equations? If you do agree, these are the basics for Newtons law. These are the basics and start for bernoulli's equation and fluid and gas dynamics.
KE=mv^2
V=Vo+aT
A=F/m
F=d/dt*(mv)
Fd=1/2*p*u^2*Cd*A(area, not accel)
Drag Force Equation (Blevins, 2003 and Munson et al., 1998 and others)
F = 0.5 C ρA V2
Notation
(ft=feet, g=gram, hr=hour, kg=kilogram, lb=Pound (force), m=meter, N=Newton, s=second)
Our calculation allows you to use a variety of units with all of the conversions completed internally. The units below are consistent units for the drag force equation.
A = Reference area as (see figures above), m2.
C = Drag coefficient (see figures above), unitless.
F = Drag force, N.
V = Velocity, m/s.
ρ = Density of fluid (liquid or gas), kg/m3.
Acceleration is a function of the sum of drag coef. of both air of an arrow in flight and arrow itself. In other words, its negative, it never gains speed after it leaves the string. Acc is positive as the Fstring is pushing on the arrow or bolt until it release that arrow or bolt. If both projectiles have the same drag as shown with the Fd (force of drag), it is phsically impossible for the bolt to drop quicker. Unless in the article the bolt is heavier, fatter diameter, fatter head, larger fletch (i.e. more drag). And it could be. The only thing that could get the bolt to drop faster is gravity due to more wieght or more drag.
So in the article did they claim to have the same wieght, same diameter shaft, same fletch same point? Its that simple. Work with me. Does it specify?
I promise, I will not be rude, I will not call you dumb, I will treat you with respect, I will work out this problem and prove to you with elementary math and well known and accepted physics. Just work with me. What makes this arthor so much more an authority on this?
I replied to you
if "
everything" was equal then you were right but I also said this isn't the way the two are set up. They don't shoot the same size and weight arrow and I said this over and over so don't try and deny it. Xbow hunters can't take an arrow out of my quiver and expect it to work like it does from my bow. Like I stated the xbow will drop faster and doesn't have the range a vertical bow does.
It says this about the arrow...
.Most manufacturers suggest arrows that are over 400 grains. There is so much energy transferred in a launch that the shorter arrow must be heavier to withstand the force.
I knew you would question the authors credentials. I can't tell you but maybe you can write and ask. All I know is I have read the same thing in other places. It's just a misconception many have that the xbow is a 100 yard weapon. It's just part of the ignorance people have about the xbow and xbow hunter.
I just hope we can get over the lazy slob stuff and respect them as fellow hunters. Thats all.