holmegaard challenge--all bows finished...pics galore

[Josh]

  give me a little while on that one. 

[medievalhamster]

Sorry, lemme try and explain things a little more...

The site Canoe linked to has a decent way of finding arrow speed without a chrono. (There's a better way to do it but maybe I'll start a thread of it's own for that)

However, I also has a little function to find the kinetic energy of an arrow.

Their equation is (arrow weight)/450*(arrow speed)^2

That would give you twice the kinetic energy in ounce feet.

After a correction to units to get foot pounds which is much more relevant given it's one of the British units of energy (I sure ain't measuring arrow energy in BTUs) you get the corrected equation of:

(1/2)[(arrow weight)/(437.5*16)]*(arrow speed)^2

If you still don't get it, don't worry the average on my thermo test that we dealt with KE on was 53 (I got a 74) so most college students don't either.

[Canoe]

Howdy M.Hamster and all,

Yes!  Please do put together a user friendly page with (perhaps) examples and charts showing / describing those Arrow Speed and Kinetic Energy formulas.  If you put some energy into it, the page would be very helpful to alot of archers here on PA.

And, maybe they'll move it to the Archive Library section for easy reference.

Thanks for your interest,
Canoe

Sorry, this seems to have gotten somewhat off topic.  But actually, I think it's applicable to this thread especially because we're compairing bows including; speed and energy, as well as smoothness of shot, accuracy, etc.

[OldBow]

Whew! You've have been busy! All holmegaards bookmarked for Sept Self BOM which is coming up next week

[Parnell]

Hey Radius - I had the second blow on me last night.  Had it tillering, pulling with a scale and not going over 45#.  It was flexing 10" and broke with no warning!  I'm wondering if the dimensions I had for the 55" length and 2" wide levers is fundamentally trouble.  That 2" is too wide for a shorter limb length of say, 14 inches working?  What do you think?

[radius]

Hey Parnell,

The first one i made in this group of three was the 2" wide limb, 12" from the start of the fades to the start of the taper down to the lever.  Maybe ur gung ho?  maybe the wood is too dry?  Maybe there was a glitch in that g'damn board and you got two breakers.  Doesn't matter.  Keep trying.  I broke one last night, 54" recurve.  God, if i'm gonna stay home on a friday night, at least the bow shouldn't break!

[Parnell]

Saw the link for the recurve break, nuts!  Looks a lot like the break I had last night, too.  Mine was close to the handle.  Oh well.  Movin on...

[J05H]

All right, let's all be honest now!  How many of you right now have a "holmie" on the bench or at least have a stave/board set aside to become a holmie?

I do. I didn't care for the design much until Radius started this project, but now I love it.

awesome, Josh, let's see what you come up with!

Unfortunately, it didn't turn out to well. While tillering, I heart the dreaded "tick" sound. I looked all over but I couldn't find anything, so I decided to just move on. I tillered it out to 30# @ 26" and did some finishing on it, shot a few arrows and then I heard it again. That time when I looked it over I found the crack. It goes in about a 1/2" from the edge of the limb and its about an 1/8" deep. The limb is only about 3/8" thick to begin with. I can still brace it, and the tiller still looks good at brace height, but I know if I try to draw it at all, its gonna snap. I've got a pic of  the crack, although you can barely see it.



I'm thinking I might try putting a hickory backing on it and re-tiller it. Until then I'll just set it aside. By the way, sorry about your recurve.

[radius]

oak is not bad, but i'm thinking 2" wide minimum to be on the safe side, and somehow you gotta keep the pressure away from the inner limbs...

[JW_Halverson]

I've given up on the neighbor letting me harvest his 8" diameter elm tree since he seems to think it adds some shade to his front yard, so I dug out a bur oak (Quercus macrocarpa) stave that was curing in the garage.  The stave is 83" overall, has 45 degrees twist (all in the upper 24 ", easy enough to take out with gentle heat), and has two knots on opposite sides about 66-68 inches from the base end.  These knots have 1 1/2 to 1 5/8 usable wood between and they cause a small dogleg in the grain of the wood.  Eleven growth rings per inch, 8 of those growth rings in the outer half inch. 

My goal is a holmie for a 30 inch draw coming in around high 40's to low 50 # draw weight. 

To determine bow length, I use the "double the draw length plus 10%" for the usual flatbows, but with a holmie there is less limb doing the bending, so I wonder what formula should I use for this sasquatch armed kid with the 30" draw?

[radius]

Cool stuff!

It's almost like a chapter in the bibles this project.

The best thing about board bows is that you can make them really wide.

aw gee

[dragonman]

Well done  Radius getting this experiment together, thats a lot of information to learn and must have helped many bowyers, good work

[radius]

thanks dragonman>

you never know until you know.  I'll play this game again, with staves of osage or hackberry or elm or whatever i can trade for this yew. 

The bow with the 1:1 ratio turned out the best.  after this i make some white oak recurve 1.75" wide based on how well the limbs on this bow performed.

[VenomBOWslinger]

funny to see this post resurfaced...Whats up Radius???

[radius]

funny to see this post resurfaced...Whats up Radius???

Dude, i miss bowmaking.  All my stuff's in storage.  I am moving tomorrow, out of this city where i have lived for 18 years.  Yesterday i split some yew, and don't have time to work on it. 

So i'm going over my old threads and i saw i missed a comment that i wanted to respond to.