Speargun muzzle velocity

1."I see this item as a tool for evaluating my own designs mostly. I don't see a big market where diver would really want this." Agree

2. "As for the Big boys, making Guns and Pole spears, I'm sure they already have their designs completely tested for this kind of basic stuff."
:thinking: Maybe it is just me not paying attention or it is true that I have yet to see ANY gun / band / spear maker EVER post ANY FPS (feet per second) numbers about their product. I continually read/hear terms like "shoots fast, slow, lots of penetration, accurate, shoots hard", etc. But I cannot ever remember seeing a true FPS written about a speargun shaft speed. Way back in the day before the wheel in archery, we were happy to get 175+FPS from our recurve bows. We didn't REALLY know how fast/slow our arrows were UNTIL we began using arrow chronographs. With the advent of arrow chronographs and the invention of the wheel on archery bows, arrow chronographs have played a HUGE role in arrow speeds and bow design. Arrow speeds have climbed from 150 to 300+fps and there is talk of 400fps designs coming, all with the help of chronographs. IMO, speargun design is much the same as archery bow design, in the context that the stored energy of the archery bow limb and the speargun band function through stored energy to propel the arrow or spear. Granted there are HUGE differences between a 200gr arrow shot through the air and a 60inch SS spear with a string attached shot through the water, but the some same concepts of trajectory, speed, and kinetic energy apply, and a spear chronograph could be a very useful development tool. IMO

Years ago Tin Man wrote about ideas of how to measure spear speed that seemed like a good approach to measuring spear speed. Perhaps his approach could be investigated.

I got fairly close with my test tank and a 1000 frame per second camera. Tin Man and I shot several short videos to study muzzle characteristics on some of his projects, and on the first rg I built to try to separate a few myths from facts, so I could design rg's based on science rather than conjecture. I put a piece of white plastic sheet with stripes every 2 inches opposite the camera, and could actually count the frames as the shaft left the gun, thereby allowing velocity to be calculated. It was a crude system by any standards, but it worked. It was also a PITA to use with the way things were set up, so I shelved the idea until I could build a new test tank (wider to get a better video shot), with a side window so the camera could shoot the video from the outside of the tank.

Because of the above, actually building the guns became more fun than rebuilding the tank and testing stuff, so the tank sits there, still a mystery to the neighbors (It's for training racing Koi! :laughing3:). It's on the list, but not on the top of the list, so I'll get back to it one of these days. For now, building guns that are a little different is more fun, so the test tank will have to wait for another day. But it's out there, waiting....

Quote from hau

1." I continually read/hear terms like "shoots fast, slow, lots of penetration, accurate, shoots hard", etc. But I cannot ever remember seeing a true FPS written about a speargun shaft speed.

Yep, I read it all the time, kind a like little kids in the school yard saying my Dad is stronger than your Dad.

Do they really know how fast it is and consider it IP. (intellectual property) or do they fly by the seat of their pants?

Lots of claims out there that they make the fastest and best product on the market, and they back it up with added sales hype.

Knowing the actual speed profile over time along with the mass of the projectile ( Shaft, pole spear, etc. ) opens up lots of great information to maximize designs.

Lots of other factors as well, but a good start. High speed camera was one thought I had, but it looked on the spend-y side.

WOODGUY, how long is that tank you made? What did you make it out of? My tank is a deep long, slow moving pool in a local river. This tank is free is use, but weather, run off from rain makes it not practical year round. This worked great when I did an evaluation of my Koah gun I bought a year or two ago.

Momentum changes can be measured too, but that's a different setup. Not seen any chatter on that topic.

The use of sound recording by Tromic was a very clever method as well.

I'll have to run all of this by "Carnac the Magnificent"

Reference link on him on Anodizing.

http://spearfishing.world/spea…pears-need-anodizing.html

Dollar and donut says he will get into the aspects of the initial acceleration of the shaft before Maximum velocity is obtained. That is where the real fun stuff is happening.

My tank was from some OSB I had forever, and was 16" high x 16" wide x 24' long, and was designed primarily for testing fairly small guns, with the idea that I could add another 8' section if I got into testing longer guns. I coated it with the liquid rubber used on roofs here. It worked pretty well, but I knew it was the wrong material when I built it- I just wanted to see how the concept worked before I spent a lot of $ on it. The "high speed" camera is definitely low end, but again I wanted to prove the concept. I got next to no helpful input, so I concluded either no one had done much, or they had decided not to share what they knew. Like I said earlier, I just wanted to see if a low cost version was do-able, and the video shots of guns functioning was the primary purpose, the velocity measurement secondary. The tank is spongy in places (Duh- what'd you expect with OSB?), so the next one will be .080" or so aluminum, but I've got too many projects ahead of it to say that will be anytime soon. Here's the thread on it: http://spearfishing.world/spea…d-speargun-test-tank.html

Tank looks great. The depth is good enough to account for gravity dropping the shaft. assume you are aiming to account for that.

What kind of cost did you have for your camera? What was the frames/sec specification? The Camera will give so much info on the harmonics of the spear as well as speeds. Getting into the dynamics of the flight is real interesting stuff.

Thanks for posting the link to the tank, I missed that one. Wonder what the cost of Lexan or Plexiglass would be to make say a 40 foot tank? Throw in some 2x4 ' s and some nails for the nail gun. Maybe ABS sheets? I do have a plastic welder that I don't use too often. Water tight welds might be another challenge for me.

If it's under $500 might be worth doing. All I need is another project thou. At least I got space in back yard to build it, the wife might not like it. but that is another issue.

Sure would be a nice controlled test bed. I could keep all of the electronics out of the water besides the sensor arrays. Could mount arrays every 5 feet to give a nice time profile.

Could also just buy a high speed data acquisition card for computer and do away with electronic design.

Attached is a titanic model my buddies made. It was remote control and was made for a local city here for a summer carnival. They had a smoke generator in there too. That's what you get when a couple Mech Engineers and a few fabricator have time on their hands. Wonder if I can talk them into making me a tank.

i remember a vid that victor abellan did on how he measured the speed of his shot. I believe this is it, fast forward towards the end...

abellan spearguns ballistics tests- pruebas balisticas 2012 - YouTube

You guys are barking up the wrong tree....I'm proud my shaft shoots slower.:yay:

My 7mm airbalete shaft leaves the muzzle @ 27 meters per second though.

Bar code readers and black and white marked cordage were used for this black op back in 1998. Tromic on here has a better speed tester if you search his posts. I'll try to link them tonight if I can.

Cheers, Don

( I found a old post I made in 2010 here:
In the interest of safety to the kids and moms next door.

Bar code reader and a black indexed line to pull,but pool tests can be very dangerous. I have seen a 6' 3/8 shaft from a 54'' gun with 5 bands put a shaft 3'' through a 4x6 timber and a exterior wall @ a friends dive shop pool. I was behind the line of fire filming the target when I heard a loud noise underwater.
Thank god no one was walking on the sidewalk in front of the dive shop The only thing that stopped the shaft was the last two of the 6 tabs.

I look at my personal guns just as tools of my sport, matched to the size of the game, I try to get within 20 feet Max and much less if I am skilled enough in the water dance. I see myself as a fly fisherman with a breath hold and no bait. Don't get me wrong I used to love the long shot and the lucky one as well from time to time.

I'm am a sinner when it comes to very dangerous gun tests, the mishaps have been many over the years when I did stupid shite in and out of the water. Thank god the worst was ten stitch's on my best friends hand.

Cheers, Don

AQUATECH Speargun

Here is a old link to Sergiy Kravancenko's tests. (2004)
I'll find Niko's work soon...

Cheers, Don

Here is a image of Tromic's speedometer. I hope he will reply to this thread as he has a mechanical friction based tester as well.

Cheers, Don

Sorry guys I can no longer find Niko Brummers images of his tester.
Most of my stored ones are on a old vintage computer I have off line.
Maybe Popgun Pete can help me if he saved them?

Cheers, Don

Here is Tromic's work in detail.

Measuring speed of the shaft | Page 6 | DeeperBlue.com Forums

He did a great job digging into this.

Don, My goal was not to evaluate spear gun shaft speeds and performance. I had seen various testing and web links on the topic. It only makes sense that this has been done.

I just want a Tool to measure more accurate changes for drag on various spear tip designs. Depending on which gun or Pole spear is shooting it was not the real goal, but relative numbers to evaluate drag reduction features. Quantifying the hydrodynamic effect was all I wanted to do.

Curious to some of the safety issues you had.

[QUOTE=Linghunt;88214

Curious to some of the safety issues you had.[/QUOTE]

1.My my first house had a pool.;) that was the big problem.;)
2. I was young and fearless.
3. On a leased house I was in I was displaced from the pool for 2 weeks while it was being re-cemented and painted. After the refill I was back in with a long 4 band gun shooting at my 3/4'' target with a high speed re-geared super8 camera. The test shot went perfectly through the only single 3/8 shaft hole and buried the 17/4 tip so deep that I could not remove it by hand. I never heard the landlords car door slam as he stopped by to inspect the recent pool work.:@
I'll be back to this...

Cheers, Don

Quote from Don Paul

I never heard the landlords car door slam as he stopped by to inspect the recent pool work.

Cliff hanger, The Story is just starting to get interesting? How old were you then?

Quote from Linghunt

Cliff hanger, The Story is just starting to get interesting? How old were you then?

30 but still dumb.:D;) I got evicted even after I paid cash for the pool re-drain, dry out and repair.

I'll start with F-up lesson # 1. Don't leave a un-doweled, un-sealed gun floating in your buddies over heated pool for 24hrs after a 6hr target session and night on the town, then resume testing the 3/8 shaft, 4 band beast. My best friend yelled ''hey can I shoot your gun''? .... things soon went very bad when the handle sheared off, cut his thumb web 3'' and I had to stop the bleeding. That gun soon had a 3/8 Ti threaded rod running through the stock.

Cheers, Don

I guessed wrong, figured the landlord was a Hells Angeles type with a chain belt, and he gave you a beating.

My guess is he doesn't rent to spearo-s anymore. Probably on his tenant application form now.

Quote from Linghunt

I guessed wrong, figured the landlord was a Hells Angeles type with a chain belt, and he gave you a beating.

My guess is he doesn't rent to spearo-s anymore. Probably on his tenant application form now.

Funny thing how we sometimes go back to trace our good times and share our stories. Just a few weeks ago I was down on Lido Peninsula on the bay and drove by my old hooch to show my 14 year old boy as I told him the story, now the property is 4 waterfront condos at 800k each.:@ but they will never have as much fun in that pool as I had.:D

Sorry for the side track guys.. on with the logarithmic decrement, laminar flow and dreams of dimpled spearshafts.;) I dream of going to the Bahamas someday, whittling a handle from a piece of drift wood, cutting a band from a truck inter tube and sharping a length of 1/4'' rebar on the concrete curve....all the while dreaming of clear warm water, tanned and oiled goddess's on towels as I swim out to the reef without a wet suit, but visions of a nice hogfish cooking on a coat hanger spit.

Cheers, Don

Cheers don! Cheers to that vision

Quote from Don Paul

Sorry for the side track guys.. on with the logarithmic decrement, laminar flow and dreams of dimpled spearshafts.;) I dream of going to the Bahamas someday, whittling a handle from a piece of drift wood, cutting a band from a truck inter tube and sharping a length of 1/4'' rebar on the concrete curve....all the while dreaming of clear warm water, tanned and oiled goddess's on towels as I swim out to the reef without a wet suit, but visions of a nice hogfish cooking on a coat hanger spit.

Cheers, Don

Thankfully this island is big enough to have an airport and still be able to get shipments from www.spearfishing.store :thumbsup2:

Don Paul---I love the side tracks sir. Thanks for sharing. :toast2: