Brace Height and Arrow Speed

[lonbow]

That's really interesting! So the difference doesn't seem to be that huge. DC, could you do the same test with different arrow weights from maybe 7 to 12 ggp? It would be really interesting to see, if different arrow weights behave differently. Did you use the same string for your tests or different ones?

[PatM]

What do you guys think of the statement that no  bow pushes the arrow more than 19 inches?

That statement is compete and utter nonsense!
Take a warbow (or a Yumi!) for example at 32" draw ... the arrow doesn't leave the string after 19".
Maximum acceleration is probably pretty much as soon as it is loosed, BUT it is still accelerating.
If the bow stopped pushing after 19 inches we would see the arrow leave the string after that!
I think the bloke doesn't understand the difference between velocity and acceleration.

As an example if you are in a car and yo floor it. Maximum acceleration is pretty much once it gets some grip and overcomes the initial inertia. Then it accelerates smoothly, pretty smooth the rate of acceleration starts to drop off BUT it is still accelerating.... it may still be accelerating when it hits 70mph, but only slowly ... doesn't mean it's stopped being pushed.
Del
 

   You could take that up with Larry but just be aware that he tends to get pouty and belligerent when someone questions his status. 

[Badger]

   Larry and I have been friends for a long time but I would have to disagree with that statement also. I am guessing that he feels the arrow leaves the string before the power stroke is completed. I think in some cases it may on bows with very low early tension but I think most bows are pushing right up to when the bow hits brace height.

   I tested speeds with different brace heights quite a bit, I came to the conclusion that if there was a difference it was negligible. This was one of the first things I checked when I got into flight shooting as the popular belief was that lower brace heights give better speeds. A better tuned bow is far more important than any minuscule difference that might be detected.

[Stick Bender]

I think Del nailed it down on his first post the reflexed FG bow really has nothing incomon with a self bow braced height wise , There is a much larger brace height window with FG bows I have braced FG bows I have built between 7 1/4 & 9 " with minimal change in arrow speed but I never brace any self bow I have made over7 in. I think arrow flight out trumps arrow speed for me brace height wise !

[Knoll]

Thank you, DC, for following through with the testing.

[DC]

That's really interesting! So the difference doesn't seem to be that huge. DC, could you do the same test with different arrow weights from maybe 7 to 12 ggp? It would be really interesting to see, if different arrow weights behave differently. Did you use the same string for your tests or different ones?

Yes it was the same string. I've only got two arrows that I use on my shooting machine. They are carbons. Reason is, I do my testing in the garage so there is only seven feet from the bow to the target. The arrows are still going crooked from going around the bow and I've broken more bamboo arrows than I care to mention. So, no, sorry, I'd rather not do more tests.

[PatM]

How center shot the bow is likely plays a fair bit into this.   Lowering the brace height on a typical selfbow is just going to create interference when shooting the same arrows. 

[DC]

Good point. The arrow I was using is very stiff. It's a carbon 300. I just checked the spine and it's 90 some pounds. A tad stiff for a 40# bow

[bradsmith2010]

what about testing  4 inches to 6 inches with a proper arrow,,
also the 4 inch brace should be a bit less in draw weight, so if it shot the same fps with less draw weight, that would be a difference,,
I have tested many times,, and maybe I am biased,,,, but have seen a 2 -3 fps difference,,
this was not off a machince so my test may not be accurate,,
I did read in volumen one, that it would make a difference as well, ,just saying
your arrow should not be going crooked even at close range

[DC]

As I explained I use a carbon arrow for strength so the spine is way out. I just grabbed an arrow out of the junk bin at the range because I was tired of breaking arrows. Once I get a few limper carbons it may start to sort itself out. Even with my best arrows that fly very true I don't believe they are going straight six feet from the bow. It's got to take longer than that to straighten up. Even when I was shooting properly spined arrows from the machine the arrows always hit the target at an angle.

[Stick Bender]

 I would think the fps gain would have to do with the FDC on any given bow in other words a highly reflexed sinew bow has probably more to gain then a self bow with 1" of set the more early draw tension I think on the glass recurve in the vid the working curve had a lot to do with the neutral gain in fps !

[DC]

That crossed my mind. If you have a ton of early draw weight you will probably gain more speed but my gut says it ain't going to be more than a pound or so. This might mean a yard to a flight shooter which can be a big deal but it won't mean beans to a hunter. Like you said a couple of post back, arrow flight trumps speed.

[bassman]

He is referring to his recurve bows

[bradsmith2010]

my arrows hit the target straight at 6 feet, I shoot inside some,,at very close range,,
wouldnt want you to break any more arrows for sure, ,but having an arrow hit straight at close range is possible,,,for sure,,,my inside target is a bag target,, it wouldnt break an arrow anyway, it has some give to it,, I dont have any experience with carbons,,
all my arrows are wood,,

[DC]

I'll see what I can do. Maybe check all the alignment on the machine but it's more than likely spine or recovery time. Not sure what I can do with that.