Rob Allen | Max Spear Velocity | Part 3 | 2023
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- เผยแพร่เมื่อ 5 ก.ค. 2023
- Stay tuned for the blooper reel at the end of the Video!
In this specific video, Rob introduces Dylan to speak further on the Maximum Spear Velocity. He will explain the testing process and the results we have achieved in more detail. Stay tuned for the blooper reel at the end.
Please enjoy the video and make sure to like and subscribe.
Have any questions?
Comment down below.
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AGAIN!, Please Please Please test an invert roller! this is amazing guys, keep the hard work.
We are, but not ready to show 😜👍
Please use bearings in all 4 pulleys!
@@dustsnow666 We only use top of the line ceramic bearings. None of our rollers are made with plastic bearings or bushes.
Fantastic video. Well explained and very informative.
👍👍
Excellent! This video will provide those who continue to attempt to squeak out ever increasing performance from their gun, (yes I am guilty of this) a tidy rational perspective of what can be obtained with keen focus on the limits of material supplying the power. One cannot supercede Physics nor material science, only optimize given physical constraints. Correct me if this is off, the key is impulse duration distributed over distance and time. Bravo. Cheers
👍👍
Great vid makes a lot of sense…
Very nice explanations & graphics! Love this as I am in love with numbers and hard facts as well :) Regards from Panama and best wishes!! >
Regards, to you to and thanks for the positive response 👍👍
Great video keep making the best spears RA
We will. Watch this space for up and coming improvements with spears.
Awesome video. Loving this type of content.
Two days prior to watching this I just set up a 900 RA gun with a roller, 16mm bands and bought a spare 7mm shaft. Wish I’d had waited a few days 😂.
So from what I can gather, the main advantage if went to a 7.5x16 would be penetration, due to the weight of the shaft. Apart from that accuracy, speed and distance between both setups (7mmx14mm and 7.5mm x 16mm) would be quite similar?
Cheers.
Yes correct. 7mm will work better with a 14mm and a 7,5mm with a 16mm rubber. It is not that 7mm will not work but as shown, it will become overpowered and you will have less accuracy. Also, not really talked about in this video, the higher speed of the rollers with the lighter spear causes way stronger vortices that can suck the shooting line into the roller.
@@RobAllenSpearfishing Thanks. That’s what I call customer service! Thanks for that info.
@@sailingpacificstar 😜👍
Lol reminds me of some guys that used to put 18/20mm bands with 7.5 mil spears. No clue how they loaded that thing either.
have you experimented with a inverted roller? Because of the pulleys the spear should accelerate at twice the speed the rubber contracts
Yes, still busy with testing.
Awesome video
Great data
With regards to the foregoing information in this video, Would it be fair then to say that a:
Stock 1.2 RA snapper roller (14mm band & 7mm shaft)
would perform very closely to a:
Stock 1.2 RA tuna roller (16mm band & 7.5 shaft)?
🤔🤔🤔🤔
Would you be able to do a test on that?
Or if you have already let us know the results?
Keep up the awesome work
Loving the science behind it
Both will basically get the spear up to similar speeds but the 7,5mm, being heavier will have more impact and penetration.
For interest sake, try the same test, but keep the mass constant by increasing the diameter of the spear and shortening the length. This might make the spear more rigid and maybe provide more force or well in theory
In a previous video we have shown that by decreasing the mass of the spear for a constant set of rubbers, the force seen by the spear is reduced at the end of the barrel. A more rigid spear will likely not make much difference to the barrel exit speed, but may help the spear maintain speed down range as the spear would flex less which should reduce drag.
@@RobAllenSpearfishing Yes your right but that's when the bands stay constant, what if you add more "power" by increasing band diameter?
For example 140cm 7mm shaft weighs 420g (standard 14mm band rob allen 100cm roller setup), which is exactly the same as a 120cm 7.5mm shaft (standard 16mm band rob allen 80cm roller setup). So does this mean you can use 16mm band on this spear due to the increased rigidity and then resulting in a faster shot? Its about a 11% decrease in mass when compared to standard overhang, so in the formula F = ma, force remains constant so acceleration increases by 11%, but does it get restricted by the maximum acceleration of the latex? Would be interesting to see how this setup will compare to the standard 100cm 7.5mm shaft roller setup and how it compares to the standard 80cm 7.5mm shaft roller setup.
@@JSJ-mn8wg It may increase the velocity toward the end of the shot but would likely not increase it as the spear leaves the muzzle, due to the bands being the limiting factor. You also would not be able to wrap the shorter spear with a shooting line in the open muzzle configuration which may cause issues.
So with a 7mm shaft on a traditional 2 band gun do the results indicate 14mm bands would be well suited? Thx for all these vids
Yes, 2 x 16mm are way to powerful and overpower the spear making it inaccurate.
Thanks for another great video.
It would be really interesting if you could do a range/penetration chart for all your guns, or at least the main variants in both standard and roller.
It's hard to compare, say a 800 Tuna vs an 800 Roller Tuna.
Does one fire further, or hit harder? Is a double wrap the limitation to either option, and therefore they are equal in distance range?
Snapper vs Tuna, roller vs standard, etc etc.
Thanks
We make so many different guns and have many set up options, sot to do an extensive trial like this will take ages. What we have learnt from this testing is, if you get the spear up to max speed, no mater how you are driving it, you can't make it go faster.
So in theory, range on a roller, when compared to a non-roller should be much the same. The variability is that the roller will take slightly longer to get to spear up to max speed, therefore the recoil will be less. The non-roller will push the spear up to max in a shorter stroke, causing more recoil. This recoil can cause muzzle lift and kick the back of the spear around causing an oscillation, slowing the spear down a little and, disturbing the flight and therefore accuracy.
This is why we recommend a single wrap for non-roller and double wrap for rollers. Remember this only all works if the guns are set up correctly. Age of rubber, length, type of rubber, water temp etc are all factors that can mess with this. I also think, the "dialed in" set up on a roller is a smaller window than that of the non-roller.
@@RobAllenSpearfishing Thanks for such an in depth response. I guess I'm struggling with the transfer from a simple single band light weight RA to your Roller Tuna. It aims high and doesn't float, those things ill get used to.
I'm not sure where I stand with my benefits, as it's thrown my aim and although shorter, is also heavier.
I'm wondering if I could have got what I needed with less weight by going for a Sparid or snapper.
Other than lack of kick back, what have I got over those guns with the T roller.
I understand its all complicated and nuonced, so there's no one explication. I guess max range with minimum barrel length was my initial reasoning for choosing the 800 Roller from my 1000 single band RA
@@MarshallRoad There are so many "trade offs." Inaccuracy can also be due to rigging. You might be getting muzzle wraps without realizing it. This is just a suggestion, it is super important to keep the shooting line as tight as possible. Some even prefer to use a spear with the shooting line through the spear ahead of the wishbone notch. We have just started to make a full shark fin spear option, with a hole through one of the fins.
In terms of buoyancy, only way to increase it is to go with a Timberline gun that has the timber to increase the lift.
My gun is an RA 800 Tuna Roller off the shelf, set up from factory.
I got the impression from Coatmans videos that all rollers shoot high, so I assumed it was this.
@@MarshallRoad Double check that your barb is closing fully. A sticky barb can make it shoot high.
Very apparent from the test shots that the recoil is also very important and id guess the limiting factor on power in a set up? Even with reduced recoil from the roller the recoil was still causing the spear to deviate from its orginal line.
Agreed.
@@RobAllenSpearfishingcan you give the rubber length used?
@@spearo16 The rubbers would have been the standard set up we use on a roller when setting up for a7,5mm spear. Basically a single 16mm, stock standard.
Hi RA, thanks for helping us shoot fish.
Trying to set up a 7mm 120 sparid with RA roller head
I want to purchase premade RA rubbers. Will the 16mm over power the shaft? Im leaning towards 14mm premade with my 7mm shaft
Yes, 16mm with a 7mm will over-power the set up. Use 14mm for 7mm spears.
Fantastic! ordered from Diversworld. Thanks heaps bro
Hi Mr Allen, would rail guns produce the same result? Are you recommand roller guns more nowadays over rail guns? lol Kind Regards, Rui
I have Speargun 90cm with roller head. 6.5mm shaft. What rubber bands would you advise me?
Try 50cm each x 14mm band.
@@RobAllenSpearfishing Thank you. 👍
Could it be that momentum of the larger spear is greater and therefore maintain a higher energy state to lessen the effect of drag despite the slower acceleration?
The inertia of a heavier spear does help it maintain speed if the drag conditions were the same as on a light shaft. Drag does still seem to be a larger factor though and in a previous video, we saw an identical spear fired from different guns slow down at a different rate due to the drag effect of the shaft bending.
@@RobAllenSpearfishing Thanks for the reply. I am very interested interested in that sort of thing and spent a lot of time pool testing. There are obviously pro and cons to everything. Personally it came down to preference. My strategy is light, surgical strikes. I use a 90cm roller with a 14 rubber and short 6.5 spear most of the time (even large yellowtail at Struis). I de-power the rubber with string extensions for reef fish. I therefore use one gun for everything from yellowtail to hotties in the kelp.
@@hendrikvogel262 Always a hard one to quantify as there are so many variables. Pool testing is always a good idea to understand how the setup should be and what works for you in your diving environment.
Idk if my “results” agree with yours, they seem to. All I know is I went to 14mm bands at about 350% stretch, I felt like my accuracy improved a lot and my penetration.
All depends on spear weight.
..that dylan speaks english like a german speaking english. where he from ?
That's an engineering accent for you😅😂
What is an actual max speed in m/s? Thanks.
30m/s is average. The max speed can vary a lot pending the water temp. 28 to 35m/s is what it is.
@@RobAllenSpearfishing Thanks. I suppose it is a material limit.
The Young's modulus of rubber is 5 MPa, the density 1200 kg/m³, so the speed of sound is ~60 m/s. Slings might have a bit of different values as a rubber, but +/- the same, and they can't decline themselves faster as speed of sound. More slings or more strong slings means faster acceleration and more recoils only.
Maybe we can get higher max speed with an inverted roller, because the "rope" moves twice faster as slings.
The invert roller may allow more force to be available to the spear toward the end of the gun, but won't necessarily double the speed of the spear.
We are hoping to do some tests on invert rollers soon and will post results as soon as we do.
so 16mm for 7.5mm it is
Yes 👍👍