Chronograph bow speed?

[LittleBen]

This isn't something talked about much on here, and I'm not even sure this should be here in the Bowyers Bench, but what the heck.

Has anyone chronographed their homemade bows?

I recently learned that there is a chronograph at the archery club I shoot at (I was living in the dark apparently). Since then I've chronographed two bows, it was interesting to compare different styles of bow at similar draw weights with the same arrow. And also to compare homemade bows to factory bows.

I'd be very interested to hear wht kind of speed (because it relates to efficiency) of homemade bows. I'm particularly interested in wood bow numbers.

I was very suprised to find that one of my wood bows shot within 2fps of a friends glass recurve at the same (or exteremely close) weight (40-42# @ 25"). My bow is a longbow not a recurve, makes me think I'm not taking full advantage of the recurves because of a shorter draw.

Lastly, I would ask that if you have a chrono, and you're going to try chronographing a bow or two, please try to include the speed with an arrow as close to 500gr as possible (just for the sake of consistency).

Thanks!

I'll start:

white oak backed ipe - 60" 40-42# @25" 137-140fps @ 515gr

holmemade recurve (don't know the model) I believe it's 58or 60", ~40# @ 25" 140-142fps @ 515gr

[Roy from Pa]

Geeze 137 to 142, Ben. Yer doing something wrong then cause I kin throw an arrow faster than that...  

[PEARL DRUMS]

Draw weight plus 100 fps is pretty standard for most bows.....within reason of course.

[Bowjunkie]

What's a chrono?

[Roy from Pa]

It's a compound bow tool that guys in Virginia use... LOL  

[John Scifres]

Somewhere is a chart of the first MOJAM bow testing.  I think maybe in Vol 4 of the Trad Bowyer's Bible.  In essence, we concluded that wood bows vary considerably by maker and design but a well made wooden bow will shoot an arrow pretty damn fast    

I'll look when I get home at the more scientific conclusions.

The weight plus 100 with a 10 grain per pound arrow is a nice benchmark.  In other words, a 50# bow, shooting a 500 grain arrow, will shoot 150 FPS.  Lots of variables though.  Enough to make most conclusions really fuzzy.

[LittleBen]

haha How did I know I was gonna take heat for this!?

Roy, welcome to being 5' tall ...thats what you get man, short arms and low fps!

I'm not too worried, most of the deer I see around here in semi-urban northern virginia hunting are like 70lbs soaking wet. Makes for an easy drag out of the woods (i mean out of the backyard).

[takefive]

IMHO those are really good numbers especially for drawing @ 25".  Curiosity got the better of me and I broke down and bought a chrono a while back.  It was somewhat of a humbling experience.  Out of the 3 wooden bows I shoot regularly, only my BBO (copied Roy's to the best of my abilities) consistently hits DW + 100 fps.  The other two are about 10 fps slower.  Underachievers I s'pose, but I still love 'em       I think my cedar arrows are closer to 450 grains, but I'll chrono my bows again and post the numbers.  Probably won't have time until the end of the week.  I know that there are a lot of variables;  draw length, string thickness and material, etc.  Also have it on good authority that lighter carbon arrows shoot about 10fps faster.  Don't ask me how I know that    :rolleyes:

[Roy from Pa]

LOL Benny. I have never shot my BBO bows through a chronograph. If I did I'd prolly be eating Crow:) But I would guess 135 to 140, cause about 45 pounds is all I desire to shoot anymore. Thing is though, the dead deer never heard the arrow coming...

[John Scifres]

BBO's, especially R/D versions, can be made to perform right up there with glass bows.  I'm talking selfbows mostly when I talk about the weight plus 100 benchmark.

[Bowjunkie]

Yeah Roy, REAL bows!    

[John Scifres]

Some selfbows, built right on the margin and tillered by an expert can come close to BBO/Glass bow speeds.  But on average, if you are beating weight plus 100, you are doing very well with a selfbow.

[halfseminole]

It was mentioned in my Penobscot thread that a longer draw length will increase speeds.  How does that add into these calculations?  I mean, I see people with 26" draws, but mine is fully 36"-that should change things, all things considered.  I did take enough physics to know that.

[John Scifres]

That is one of the many variables.  Overall, the longer the draw, the more efficient you can design a bow.  But, that doesn't mean an efficient bow can't be designed for shorter draws.  Many a buffalo fell to a 20" draw plains bow.

[halfseminole]

That seems counterintuitive-it would seem to me the longer the limbs, the sloppier you can be and it still work.  Shorter limbs would have to be designed better simply to function.

[MoeM]

I remember Kenny`s test thread- there was a large difference in speed between 28 and 30" - First Iwondered but imagine 10% more draw with same bow causes 10% more weigt AND 10% more powerstroke my understanding of physics tells me it`ll give bout 15% more speed; 160fps towards 184fps can "make a difference" ^^

[John Scifres]

Working and being efficient are different things.  And limb length and draw length are different things.

[Black Mockingbird]

I bought a chronograph(the extractor of truth) a few years ago as a tool to help me build more efficient and better performing bows...I thought my bows were pretty quick until I shot em thru my new toy...they were all mostly average to sub par,and only one being above average....you have to be careful with them as they can be +/- 10 fps depending on how you draw and release the bow...a slow draw all the way to anchor and then a long hold will be considerably less than say a flight archers release...you have to be consistent everytime you shoot an arrow if your doing it by hand and not with a shooting machine...

Your numbers to me seem kinda slow to what can and should be achieved with that type of bow...I don't like posting speed numbers unless it was witnessed by someone as well...but I have made 25" draw self bows shoot a 10 grain per pound arrow in the mid 170's....I'm not a fan of the general rule of draw weight plus a hundred yards..cus that's only with a 500 grain arrow...and its a unfair advantage as some bows are just not gonna shoot that weight arrow well coming out of the bow...arrows have a lot more to the speed than people think...in flight archery the arrow is half the equation IMHO..I like the general rule of shooting 10 grain per pound arrows from a bow to test it...as most bows will shoot that arrow well enough to get a good enough read on how efficient the bow really is....a good self bow should shoot in the 160's,and a smoking fast self bow should shoot near in the 180's...a good all wood laminate should be in the 170's,and some of the fastest all wood laminates have shot in the 190's...but only a handful of bowyers on the planet are capable of such numbers...

[Roy from Pa]

Hey Chris, bring that with ya the next time you come over to build bows. I'm curious what my bows will shoot.

[Black Mockingbird]

Okay Roy... but don't cry when it says 0 ... lol