Do you worry about Front of Center?

[nchunterkw]

I measure that way because an arrow flexes about the midpoint if the shaft during flight and flexes at the balance point at impact. So I want to know where the balance point is with respect to the center of the shaft because that is where the shaft will be flexing regardless of how long the point is.

[Lake shooter]

Maybe so, but we're talking arrow flight here, not flexing after impact.

[Limbs and Sticks]

FOC really over rated, at the speed these bows shoot today it really DON'T matter when hunting if you can build a arrow to fly where you aim, in 3D the pro's use 10 to 12% FOC.

Wes

[nchunterkw]

Maybe so, but we're talking artow flight here, not flexing after impact.

Either method is fine. The method I use is the AMO standard.
Here's some good info on the topic.

http://archeryreport.com/2010/09/arrow- ... calculate/

[awshucks]

Ask Danny Miller about FOC and sit back and listen..... He's told me he'd shoot 100% if he could get it, lol.

For a 20" [all I shoot] arrow, just figure the diff from middle to balance point and multiply times 5%.........Close enough for me.

To get that figure for other length arrows, divide the length into 100%

[nchunterkw]

Ask Danny Miller about FOC and sit back and listen..... He's told me he'd shoot 100% if he could get it, lol.

For a 20" [all I shoot] arrow, just figure the diff from middle to balance point and multiply times 5%.........Close enough for me.

To get that figure for other length arrows, divide the length into 100%

I have done just that and you are exactly right. He likes high FOC arrows.

FWIW your formula is the AMO std too. dividing by 20 (your arrow length) and multiplying by 5% are the same thing.

[flightattendant100]

At a normal hunting type range, ( less than 30 yards) you can darn near shoot rocks out of your Excal and make a kill shot. Quality shafts, proper fetching, and. Quality broadhead= you got no problem. Anything better than minute of whitetail, is just icing on the cake.Have fun, experiment, play around with the set ups, but most will shoot good. It's a great situation to be in.

[awshucks]

FWIW your formula is the AMO std too. dividing by 20 (your arrow length) and multiplying by 5% are the same thing.

Didn't know that........I just 'figured' if a 20" arrow is 100%, each inch is 5%. It's all good.......

[vixenmaster]

No i don't worry about the arrows FOC. I make my arrows n test their flight out to any distance i expect to get a clear clean shot on my game. The farther i shoot the more wt. in my arrow i want fer momentum & penetration

[tomasw1]

Thanks for the replies. I'm an IT guy so I love plugging the numbers and all the research. Certainly an OCD type with this stuff. You guys are sure a great resource, thanks again.

[ehntr]

Confucius say: He who loads up front end........leaves his worries behind.

[strum]

im of the school of thinking that says we definitely need the front to weigh more than the back .but I don't really think about it much anymore ..back when we were shooting 30" arrows out of our 200fps verticals I think it made a world of difference and I used to measure and balance and calculate..
Its interesting to play with the numbers and try things. im just too lazy now

[nchunterkw]

Confucius say: He who loads up front end........leaves his worries behind.

[Walkin]

Here's some more info to fry your brain with.

An arrow is a rocket; a coasting rocket whose fuel burnt out when it lost contact with the bowstring.

In a rocket there are 2 main points of concern; the CG (center of gravity) and the CP (center of pressure). The CG is where the actual rocket balances if you were to put it horizontally on a knife edge. If you make a 2 dimensional cutout of the rocket on a stiff piece of cardboard and then place that cutout horizontally on a knife edge, the CP is where the rocket profile cutout will balance.

Rockets rotate about the CG axis. All resistance forces that stabilize a rocket like the air pressure hitting the body and fins(fletchs) act at the CP.

As long as the CP is behind the CG the rocket will try to stabilize itself and keep its head into the direction of travel. CP ahead of the CG and it will tumble head over heels.

The distance that the CP is from the CG is a force moment; it is a torque force. That equates to the amount of force that the rockets' fins or arrows' fletch in this case, contribute; bigger fins equals more stabilization force equals more drag and possibly over stabilization, if it becomes a high frequency oscillation.

So you see, Front of Center is an over simplified way for the average Joe to think about arrow flight.

Stay tuned, next weeks discussion will include hot topics such as spin stabilization and the ever present northern hemispherical Coriolis Effect; bring your Tylenol.

Worried,
Joe

[ehntr]

Here's some more info to fry your brain with.

An arrow is a rocket; a coasting rocket whose fuel burnt out when it lost contact with the bowstring.

In a rocket there are 2 main points of concern; the CG (center of gravity) and the CP (center of pressure). The CG is where the actual rocket balances if you were to put it horizontally on a knife edge. If you make a 2 dimensional cutout of the rocket on a stiff piece of cardboard and then place that cutout horizontally on a knife edge, the CP is where the rocket profile cutout will balance.

Rockets rotate about the CG axis. All resistance forces that stabilize a rocket like the air pressure hitting the body and fins(fletchs) act at the CP.

As long as the CP is behind the CG the rocket will try to stabilize itself and keep its head into the direction of travel. CP ahead of the CG and it will tumble head over heels.

The distance that the CP is from the CG is a force moment; it is a torque force. That equates to the amount of force that the rockets' fins or arrows' fletch in this case, contribute; bigger fins equals more stabilization force equals more drag and possibly over stabilization, if it becomes a high frequency oscillation.

So you see, Front of Center is an over simplified way for the average Joe to think about arrow flight.

Stay tuned, next weeks discussion will include hot topics such as spin stabilization and the ever present northern hemispherical Coriolis Effect; bring your Tylenol.

Worried,
Joe

We're supposed to say "This is not rocket science".

I can talk mean aerodynamic chord and the distance (arm) X weight = moment (tourque) effect..................but rocket science.......no nothin bout that.