Cast of bows, short vs long?

[skychief]

All else being equal (yes, I know, hardly possible), which bow will be quicker, longer or shorter?

Mainly interested in how length affects speed of recurves, more so than longbows.

Thanks for your thoughts, Skychief.

[Thumper Dunker]

I think this is right. The limbs are the same stuff and thickness. You shorten them and they become stiffer just like arrows so the short one will be higher poundage and quicker short limbs have less area to move and they do it faster. but the longer limbs will be smoother . more relaxed. ?  But woods and other materials are almost never equal.

[damascusdave]

I have what is supposed to be one of the fastest recurves ever made, a Hoyt Desperado, and the formula on that one is a 23 inch riser with extra short limbs...I just finally figured out how to set up my Chrony so it works most of the time and I have been running arrows from quite a few bows over it...my conclusion when it comes to speed is that nothing is conclusive, nor do I really care how fast a bow is...shoot reasonable weight arrows with sharp broadheads accurately and they will all do the job

DDave

I think with some bows the longer ones may be quicker because of the part of the limb that is doing the work.

[ChuckC]

I have to believe that just because a bow has 40" or only 20" limbs it doesn't mean all of the 40" limbs will bend or bend well, meaning mass in motion and return, nor does it mean that very limber 20" limbs may not have more actual mass in motion than the others.  

I know I didn't say that well, but, Lots of physics and motion dynamics going on here.
CHuckC

[mike g]

I'm no rocket scientist....
Butt isn't speed and cast, Two different things..?
    A friend of mine had a Blackwidow recure and I had my HH Big 5.
    Arrows and poundage on both where the same, His bow was faster than mine on the chrono, But my Bow would cast an Arrow further....

If a slower bow can shoot an arrow farther, that increased cast distance would have something to do with the arrow flight.  If the BW made the arrow go through a lot of squiggles, that will eventually slow it down.

[WESTBROOK]

Two arrows of the same weight launched at the same elevation...the faster one will go farther...it has to. Provided they are properly tuned to the bow they are shot from, as Pavan implied.

[ChuckC]

Yup, as soon as the arrow leaves the bowstring, it stops getting pushed.  All else equal, the one going fastest at that point goes farthest.
ChuckC

[skychief]

I posted this because I have been shooting a 56" recurve that seems faster than my longer bows of the same draw weight.

It seems I have read differing opinions on which would be faster in the past.   Maybe we need a rocket scientist for "the" answer.  Lol.

[McDave]

Originally posted by ChuckC:
Yup, as soon as the arrow leaves the bowstring, it stops getting pushed.  All else equal, the one going fastest at that point goes farthest.
ChuckC

I agree with your statement, as far as it goes, but let's examine what might not be equal:

1.  More fletching on the faster arrow could slow the it down to the point that the arrow with the slower initial speed passes it downrange.  The extreme example of this would be a flu-flu, but simply having 4" feathers on one and 5" feathers on the other could make the difference as well.

2.  Assuming the faster arrow is a lighter arrow, the arrow with the slower initial speed might pass it downrange, as lighter arrows are slowed down more by air drag than heavier arrows.

3.  Taking the subject a bit farther, it is possible that bow A will shoot a light arrow faster than bow B can shoot the same light arrow, whereas bow B might be able to shoot a heavier arrow faster than bow A can shoot the same heavier arrow, because of differences in bow design.  I've heard (and here I might be getting on shaky ground, because this is outside of my direct experience) that a bow with a long riser and short limbs is optimized for shooting light arrows fast, whereas a bow with a short riser and long limbs is optimized for shooting heavier arrows.  So it is possible that one bow might win the speed contest with light arrows, while the other bow might win the speed contest with heavier arrows.