We Built The FASTEST Bow EVER (Almost Dangerous)

So, here's the thing... Well, first off, I was (and am no longer, but was) the director of engineering at a major bow manufacturer a few years ago. To meet our spec, we would design our bows to 100 dry fires. The goal is and always will be strength vs weight of the bow components. So, we would dry fire and see what broke, cracked, yielded, bent whatever and then "beef up" that component and dry fire again etc. So, once we got to where we could 100 times out of 100, get NO breaks, cracks, yields, bends, in anything with dryfires, that would be our final design for the year/series etc. Strings break, risers bend, limb pockets twist, limbs crack and delaminate (a lot), etc. Another thing is that we would test at IBO standard of 80lbs of draw weight and 30 inches of draw. That is the criteria that we would design our bows to. You can, and we did, build some custom bows for some really tall archers, ie 36-38" draw length, and some Africa hunts we would design bows to 120lbs of draw weight. These were custom built monsters. And, of course we would "play around" in the shop with these prototypes basicially, and when you get really long draw lengths, you can get some really good speed. But, the goal was to get a 5 grain arrow at 30inches of draw to as fast as possible of course w our speed bows. 5grain/lb arrow is the IBO standard, meaning at 80lbs of draw weight, we would shoot 400gr arrows. The biggest limitation, and it's the one that EVERY manufacturer runs into is the limbs. There are VERY FEW limb manufacturers, like VERY FEW, like... one, lol. There may be more now, but I doubt it. Anyway, basically the manufacturer would send us the spec sheet on all of their materials. We would work with the spec sheet and try and design the max load per the geometry for different matrices (layers) of materials that we had available. There is only so much you can do, before you load the limbs too much and they basically just crack and delaminate in catastrophic failure. So, again we would design and push the geometry to the max tensile (top of the limb) and compression (bottom of the limb) loads possible. Then once we designed the limbs and the geometry and the cam loading profile, we would test on the dry fire machine. 9 times out of 10 the manufacturer would be very, lets say lenient, on his spec sheet, and we would delam almost always from our first design. So then we would back off on our limb geometry until we could get the 100 dryfires wo LIMB failure. Then would would check everything else. Another common failure mode was the cam axle. It would bend, and of course we want the lightest bows possible, so then the limb pockets would twist as well. So, then we would do that for every design for the year, and we would shoot 10 shots with a "normal" arrow setup (3, 3 inch fletches, proper FOC etc), and send all of that data to the marketing group. Then the marketing group would have us cut off the fletches, use the pointiest field tips, use our machine to draw and shoot 10 shots (rather than hand held releasing) to get their speed numbers for the season, and take the fastest ONE (Usually about 10-15fps faster than hand held, normal arrow) shot and use that as their number for the marketing materials. No peep, no nock, bare string, unless we could play around with some crimp on nocks and different placement on the strings to get faster numbers. Sometimes we could, sometimes we couldn't, there would be a lot of trial and error. But, anyway, the moral of the story is, don't do what these guys did. Anything less than a 5grain arrow, and its only a matter of time before your bow explodes. Based upon what these guys were doing, I would say that the string/cables would be their first failure. They are not designed to be twisted that much. Better to just use shorter cables to begin with. The next failure would probably be the a tension crack on the top layer of the limb glass. As far as cable twisting and all of that, when you push things to the limit like this, sometimes its best to just get a custom cable made with fewer strands. What you want is a little "give" in the cable/string system. With a higher number of strands, its really a hard "shock" on the entire assembly upon release. What you want is just a little "give" to help reduce the shock once the bow becomes unloaded upon release. The limbs and the cam and the draw length are all a "system." You can (in essence) make the limbs thicker to get a higher poundage ( our African bows), and you can lengthen the limbs when you add draw length etc. So this "system" is designed to put the maximum load on the limbs at every point during the draw cycle, and change any one thing, ie cable length (cable twists), and it messes up the whole system. The next thing is the spine on the arrows. We would use high speed photography and see actually how far the arrows "bowed/bent" upon release. And, the "effective" spine is very dependent on the weight of the tip. So when these guys lightened the tip (75gr) they actually stiffened the effective spine of the arrow system. You can go down to a 4gr arrow, usually, with a light tip, and get some really amazing speed. In this case when these guys were shooting 95lbs, that would equate to about a 380 grain arrow. And, you SHOULD be safe for about 200-300 (maybe as many as 500) shots, depending upon the bow manufacturers own internal design criteria. But, anything less than 4gr and you are really, really pushing it, and it's just a matter of time. So, wear safety glasses, and a heavy coat, because that thing WILL explode on you. Also, these guys, even at what they were doing, I would completely disassemble the bow, look at the axles, spin them and see that they have ZERO wobble, and also the cam bearings may "hog out" and become a little egg shaped. So, just be careful out there guys.

Fun video! The set up was 3.3 grains per pound roughly in a short amount of time the limbs will give. IBO is 5 G per pound and was set a long time ago, a person would think tec advances would allow us to drop to maybe 4 to get greater speeds but ive pushed it and it doesent last long. Also, 44 years old now and use to shoot 83 lbs black night and a 80 lbs PSE for a short while and if you LOVE shooting now you will when your my age too...take care of them shoulders, no good repair surgery really available.

Two tips for the chronograph. It works by checking the time between 2 "shadows" cast by a projectile going over the top - the first at the first light gate and the second at the second light gate. So, 1: You are right about your indoor lights. They flicker 60 times a second so both gates see a shadow 60 times every second. It can't tell if that shadow is the projectile or not. The sunlight is constant so no confusing flicker. and 2: You are standing too close to it. The front gate is being triggered by the arrow but the string is still pushing it so it is still speeding up. You would see a higher and truer speed if you stood a couple feet further back from the chronograph, give the arrow time to be off the bow before you trigger the first light gate.

If anyone was wondering that arrow at 17 minutes when he upped the poundage to 90 was off camera in under one frame lol

Now that's my kinda bow :)

I built numerous bows in the 1980's that were in the 100-135# range. They were all round wheel bows back then. I was shooting 620-1200 grain arrows out of them. Still have the 135# bow, but can't pull it anymore. Fun to watch young guys with good shoulders mess around. I really enjoyed those days. Thanks for the video Chris!

If you’re going to use your ProChrono inside, you’ll need a light kit for it to work properly. Great video! Thanks for sharing. 👍🏹👊

"I don't read the instructions, because I'm a man..." "Well everyone, it's a couple days afterwords. And we figured it out." Yep, checks out.

You need to try APA king cobra bow it will be faster than that at that poundage by far

I'm old enough to remember when Beeman started making carbon arrows. My dad was a very avid bow hunter. I remember the day he picked up his new Beeman carbon hunters.After shooting Easton XX75's for years seeing the speed and penatration of those carbons was unbelievable. It was crazy the lazer beams that Onieda Eagle would shoot lol. Blast from the past. Back when overdraws for shorter faster arrows were a thing

You need natural light for that chrono, the frequency of indoor lighting in Hz is basically flickering. Therefore the projectile is passing during an absence of full light, the sun doesnt flicker, it's a constant source.

If you want more, try the Mathews Monster Safari, 85 pounds and 350 fps out of the box If you pump it at 95# and use a lighter, shorter arrow, May be you can up to 400fps

Would be interested to see Chris do a bow build on a Mathews Safari

I can just see the Mathews engineers cringing when you loaded them limbs!! Your a brave man

Jim Burnworth is on video like, 10 years ago shooting an arrow over 400fps out of a Bowtech... and he didn't even "soup up" the bow to do it.

Chris bee: 90 is so heavy Cam Hanes: 90 is a warmup

Put a string of White LED’son top of those skyscreens. I will work everywhere.

I was actually wondering what those compound bows are capable of if one puts them through the stress you did . A really cool experiment I thought . I’ll leave the 100 pound stuff to my long bow though . A little safer lol Again cool experiment. Cheers

the brace height also increased which resulted in less time of the string pushing the arrow that's why the speed not jumping up so much

High Country Archery had a bow, the X-12 I think, that advertised 400 fps with their super light speed pro arrows. I never saw it in person but I remember reading about them.