Runner calculations conventional guns bs inverters guns

[rollerGR]

1. setup with 4 bands 7.5mm 145cm on a barrel gun? Wtf, I might really convert one to 3x14.5 at 350% or 3x16mm 320% but I cant imagine the recoil... My Oceanammo Pelagic 120 triple 3x16mm 300% 4.5kg wooden gun already kicks hard.
- Muzzle everything sits pretty flush
- It might be muzzle lift, even with 150g extra on the muzzle head there is insane amount of force lifting it and since you are 1.5m away the lever created is insane. From that distance the hold is barely efective... A tiny lift can couse tremendous changes if it happens early in the flight.
- RUBBER RIPPLE EFFECT? This is something I am curious how big part it played. Ive had numerous times when the bands would get UNDONE (jump out of the bottom attachment point) DURING THE SHOT with like 15kg more or less preload. JUST HOW?!!!

Worst case my buddy couldnt get this shit to work on 120cm on heavy barreled carbon either. Rip slip tip when the shafts STEEL CABLE got ripped on the muzzle when the wishbones pinched it as it was flying and shaft went flying down into rocks. yaiks...
Got the video too from very close...

Rest points I am almost dead atm and tomorrow water day, but I do not think we can threat rubber propulsion speed with force on the same values as its non linear I believe?
The total potential energy of the loaded rubber CAN be the same in the equation, but it can be achieved by either more work or more speed no? My brain is fried atm.
If thats the case, the only reliable way would be to idealy separate each part of the energy release in segments to get proper datya but that would require something like 1k+ FPS camera at least and very fast shutter speed to calculate segments.

found the videos i had in mind


some old ones from a now defunct channel (Rip) but it's those kind of setups. oceanborns are lighter than 4.5kg and the recoil doesn't seem too bad. oceanammo as far as i know makes pistol grips which have very high offset and low offset is one of the main ways to reduce recoil due to reducing the lever arm and directing the recoil straight against our arm ergo some of our body's mass is added to the overall mass
what kind of shaft are you using? you could also experiment with pure latex 16mm bands cut at ~3,2 or 3,3 to offset a bit for the lower overall load

yes rubbers vibrating is a common issue and i've had it myself both in rollers and invert rollers but it's especially bad in rollers. a way to mitigate it is very big preload of ~1,8+ but the best way is by modifying how they tie or loop around the anchors/mushrooms
you can feel that in your hand as well just grab a piece of rubber with one hand stretch it with the other and release. it's going to wobble hard once it contracts back

yes force/energy and i guess speed too are not linear but exponential depending on stretch coeff which would also be affected by material properties since this plays a role too - i have done some digging around and if the UV coating is too thick it can make band difficult to load but at the same time reduce its energy potential since it does not behave in the same way latex does

yes total energy can be increased in various ways, more than one methods can work. some will add more recoil while others won't. increasing a rubber's speed (diameter or stretch) will also increase its potential work output but a higher stretch can also increase work done on the shaft due to a larger propulsion distance. not sure i got your question correctly so correct me if i missed the point. but generally we can achieve similar or identical energy with two different rubbers, one being thicker and stiffer at ~3,0 and the other being thinner at ~3,7.
theoretically the thinner and shorter band would be faster because its mass is lower while its force/energy roughly equal. higher energy means higher potential max speed above its standard threshold (in this case ~3,0 elongation) with force being near-equal and determining efficiency in affecting the shaft's energy/speed by working against drag/inertia
so theoretically slightly thinner bands with higher stored energy are more efficient than a thicker longer band of similar force, plus they have bonus increased work due to additional propulsion

 

[Sorcerer]

I've got one with ergonomic grip.
Currently 8x160 but I'm waiting for 8x150 drop barb from RA.
A bit short but it's almost impossible to get shark fin one at 160cm.
Last year was able to get pretty good season finisher with it landing the last hoo as I ordered the gun late. Will see starting September how it goes, but I have to figure out other BHW gun for me/clients that will be foolproof without putting more money on the line...
I think if you are to spend 300€ for a gun for BHW, spend a little bit more and seriously get the heavy wood. It's not that more expensive and you remove one huge factor for dialing the gun.

My buddy got new cressi victory 120 with triple 14mm and I must say I like the gun a lot, though again, waiting for September for real life results.
Cherokees have been really good for us since early models, salvimar hero would be probably the best cheap BHW gun if their triggers didn't suck ass and I am gonna go ape shit on salvimar again, oh boy the history loves to repeat, but this time I am gonna go really public with exposure.
Waiting for cease and desist letter lmao.

 

[Sorcerer]

Btw playing with tecnicaspearguns calculator.
When we have same force on the trigger (so total energy stored) in standard gun,
longer and thinner stretched bands win by huge margins with muzzle velocity.

So even thought the total energy delivered is the same, the application of it is different.
That's why knowing the point 3. Would be so interesting.
I get almost +6m/s with same energy stored.
3x14x380 vs 3x16x320

 

[rollerGR]

hmm 8mm mass is definitely contributing to the recoil. you could definitely get a 7,5 or even 7,25 but i don't know if that would be enough penetration for your needs

cheapest bw without recoil would probably be a beefed up invert roller with an added floater for buoyancy. but it would be difficult to use if someone has not used a gun like that before

Btw playing with tecnicaspearguns calculator.
When we have same force on the trigger (so total energy stored) in standard gun,
longer and thinner stretched bands win by huge margins with muzzle velocity.

So even thought the total energy delivered is the same, the application of it is different.
That's why knowing the point 3. Would be so interesting.
I get almost +6m/s with same energy stored.
3x14x380 vs 3x16x320

yes it's significantly more work done for the same amount of energy. additionally the shaft delays deceleration so it doesn't "bleed" as much energy compared to a more standard band length. in essence, the energy of the rubbers is the same but the shaft's energy is higher. similar reason rollers and invert rollers achieve higher energy with lower loads
the only issues with the calculator is that it does not calculate booster bands well and deceleration over longer distances but other than that it's a great tool to build on