Adjustment of Spear guidlines

[Rocca]

So, a little background:
Low-profile spears are becoming more and more popular - the current guidelines for Class 3 weapon construction say nothing about a minimum diameter of weapons tip. Current foamsmithing techniques rely on the 2.5 inch rule for spear tip size. Ergo, some low-profile spear designs are designed with 2.5 inches in mind.

Spears with small heads hit too hard. The relationship between the increase in surface area and the increase in applied pressure (psi) is inversely proportional - if a spear head decreases in size, the pressure exerted will increase. Additionally, small impacts in the chest area can be extremely dangerous, (see http://en.wikipedia.org/wiki/Commotio_cordis, for one instance). Extra foam of the tip can help decrease the applied force, but the more foam, the higher the chance of bending, negating the foam in the first place.

Point:

I propose a rule change (though I don't know the specific wording) that would regulate the minimum size for spear heads. This would hopefully be a change that allows for the cool, lower profile construction that we have going on right now, but that would limit things to within reason. Basically, I don't think that the average hit test on small spear heads is sufficient enough to determine their safety, and, since smaller spear heads are dangerous, providing a minimum that is more around 3 to 3.5 inches (if thats enough) would be good.

*shrug* That's my two cents. I'd like it if people could discuss to get a feeling for this. I have run the numbers, etc. but I'm not 100% sure of the applicability of the calculations so would prefer if more experienced foam smiths and rule makers took this on. Also, yes, I got my rib broken by a LP spear at Chaos, but NO, I am not a wilting flower * about how i got hurt. It is precisely because I have been doing this sport for so long, and because of the bizarre nature of the impact, that has lead me to decide this would be a good idea.

[Magpie Saegar]

Spears with small heads hit too hard.

I've been hit by some that don't. And if they do, they should fail weapon check. As long as they don't hit too hard and don't fit into an eye socket, what other regulation is necessary?

[Rocca]

Its not the "feeling" of the hit per say (perhaps hard was the wrong word, maybe "too much penetrating force?) - the smaller impact means that the concentrated force goes deeper into the body, potentially causing more damage (or at least, that's my understanding of it . . . ). Also, the term "small spear head" applies to heads of many different sizes, so being hit by one that is fine may not be applicable to another small one because there is no size uniformity. Additionally, I think that yes, the eye socket rule is a good rule, but its not the only thing that should apply to spears - people are hit in the head way less with spears then other objects, spears tent to thrust at the feet or torso (just based on whats available really), so while the eye rule is necessary for minimum standards, I think another minimum would be beneficial.

[Big King Jimmy]

Just to let you know, Magpie is in Hydra with me, and as far as I know we built the first low profile spear heads. When he says small, he means exactly what you're referring to.

[Rocca]

Just to let you know, Magpie is in Hydra with me, and as far as I know we built the first low profile spear heads. When he says small, he means exactly what you're referring to.

Thank you, that will help.

Basically, I'm sitting here running numbers and looking at past injuries, and experience, and I'm worried about the safety of these things. I've been hurt before in Bele, and seen rib injuries etc., but "small spears blah blah insert first post" worry me. I'm glad that there are people who have really small spear experience with them joining this discussion. *shrug* I'm still not convinced, but then, arguments haven't really been put forward have they?

[bo1]

we, hydra that is, did start making the small headed spears a few year ago. we havnt had any injries with them of any significance. i was 2 feet away from you when you were injured, so i have a perspective on what happened to you at chaos.

the facts are, the spear passed check that day, and the following morning. so i think it is a safe weapon, i am sad that you were injuried but i think injuries happen. now i am going to make sure at fest that we check that particular spear thoroughly, i will most likely stick someone myself with it. the problem is most likely that people get lax on check and dont test to 100%.

i personally dont make low pro spears smaller than 2.75, but that is hardly much larger than what you were hit with. i feelings are that the 2.5 rule is fine as long as we check them to 100%.

[Magpie Saegar]

Yeah, what Big Jimmy said. And I own two "medium profile" spears that are about 3-3.5 inches. And I'm not saying you're right or wrong... I don't have a strong feeling here, just a little experience.

Do you know how the one that hurt you was made? I'm not at all an expert, but I know that there are some ways of doing it that just won't work.

Also, Arrakis should get in here. He and Poo both wrote tutorials that I based my spears off of (http://geddon.org/index.php/Low_Profile_Spear), and he generally is good at the numbers and such.

Or Chicken. He's been doing a lot of researching into developing new tech in this area.

[Rocca]

we, hydra that is, did start making the small headed spears a few year ago. we havnt had any injries with them of any significance. i was 2 feet away from you when you were injured, so i have a perspective on what happened to you at chaos.

the facts are, the spear passed check that day, and the following morning. so i think it is a safe weapon, i am sad that you were injuried but i think injuries happen. now i am going to make sure at fest that we check that particular spear thoroughly, i will most likely stick someone myself with it. the problem is most likely that people get lax on check and dont test to 100%.

This has less to do with that I was injured (I've been injured before, and seen injuries from weapons before) and more to do with the response I've received from doctors and engineers about the exact nature of the force, surface area being the primary component. Also, when I run the numbers, it seems a little ridiculous to be so lax about the increase in applied force. Also, seeing someone get injured doesn't really give you any more perspective on the safety of the weapon - checking it afterward does, which you and I both apparently did. That's the reason I think this needs discussed - that spear style passes weapons check but, in my opinion, applies too much force when not applied to the relatively flat surface of a back (which is were we weapons) .

[Spike]

Basically, I'm sitting here running numbers

Also, when I run the numbers, it seems a little ridiculous

Show us all these numbers you've been running.

[The Great Gigsby]

A spear with a 5" profile can be just as dangerous as a spear with a 2.5" profile.

Actually, adding mass to a weapon in the misguided attempt to make it hit more "softly" can make it even less safe and is an extremely foolish way of fixing a problem.

[edit]Case in point: I passed a fatty Edhellen spear at WW7 (actually from your group Rocca, although that's beside the point) that ended up getting slammed straight into my solarplexis. I spent the next two minutes dry heaving in pain. Spears are gonna have a ton of force behind them, there's no way around that.

I'm in the **** happens camp. We should evaluate how we construct and test our gear instead of adding restrictions.

[Cade]

I also think we need to be testing weapons better.

Every time i see checkers test spears, its always two handed which is not the same as being hit with a 100% one handed thrust. I can take a spear and knock someone back with a two handed thrust to the torso. I can then take that spear, step back a few feet and knock the same person on their * with the same spear one handed leaving them on the ground gasping for breath.

I don't pretend to understand or know the math, but one handed spear hits harder. Maybe something to do with acceleration? Why aren't spears checked for one handed thrusts?

[Big King Jimmy]

That's pretty simple, with one hand on a 7 foot spear, you have zero control. You're trying to stab someone, we use the back because it's the easiest place to do it over and over consistently connecting.

[Cade]

That's pretty simple, with one hand on a 7 foot spear, you have zero control. You're trying to stab someone, we use the back because it's the easiest place to do it over and over consistently connecting.

With all due respect i disagree. Hitting a completely motionless target from a fixed distance one handed is not difficult.

Hitting a moving target, from a variable distance who more than likely has a shield one handed is harder, but by no means is it so hard to do that one handed spear shouldn't be checked. I would say most of my spear kills come from one handed stabs.

I think the question becomes, does one handed spear hit harder than two handed? If the answer is yes then we need to start checking spears for high impact one handed stabs regardless of how rare or common they are.

A spear with a 5" profile can be just as dangerous as a spear with a 2.5" profile.

Actually, adding mass to a weapon in the misguided attempt to make it hit more "softly" can make it even less safe and is an extremely foolish way of fixing a problem.

The extra weight added to a spear to make it 5 inches rather than 2.5 is really negligible. Its measured in ounces, not pounds...so its not like your doubling the weight. the extra padding that doubling the tip size will support would more than make up for the increase in mass.

[The Great Gigsby]

How does requiring a weapon to be bigger make it inherently more safe? It only exacerbates and complicates the problem.

[Cade]

How does requiring a weapon to be bigger make it inherently more safe? It only exacerbates and complicates the problem.

If we were talking about simply requiring the spear to be of a larger size without requiring more padding to be used on the tip then you would be correct, but we aren't. Bigger doesn't make a weapons safer, but more padding does make it safer.

Right now a 2.5 inch wide spear head can only support so much padding on the top without flopping over. A 5 inch head could support more.

I am not advocating requiring a rule change here. In fact i think requiring a minimum is unnecessary. I simply think checking one handed stabs will do the trick and having spears fail weapons check will lead to people adding padding to the tip to make it pass. If people have to increase the diameter of their spear to do it then so be it. The logical outcome is that spears will increase in diameter for a while till someone figures out how to do a low profile spear safely again.

If people are getting hurt by low profile spears, then weapons check needs to be better. This forces the spears to be built more safely, which leads to fewer people getting hurt. No new rules necessary.

[Big King Jimmy]

I would say most of my spear kills come from one handed stabs.

I was about to tell you you were doing it wrong, but now I realize that I think you're talking the "hand at the back of the spear, dude just out of my reach, lunge stab" and not the "This is totally awkward, I'm holding the middle of this spear and trying to do some weird underhand or overhand thrust."

[Rasheab]

Or "pool cueing" it? (Forward hand guides, back hand provides power.)

(Not sure if that's what you were talking about Jimmy, so tossed it in in case.)

[Cade]

I would say most of my spear kills come from one handed stabs.

I was about to tell you you were doing it wrong, but now I realize that I think you're talking the "hand at the back of the spear, dude just out of my reach, lunge stab" and not the "This is totally awkward, I'm holding the middle of this spear and trying to do some weird underhand or overhand thrust."

^ yea this. The hand at the back of the spear.

[Arrakis]

Okay.

So.

The issue at hand is not as simple as the "size" of the foam head you, the weapons checker or opponent on the field, can see. The primary influence on energy transfer and pressure at the apex of a spear thrust is a factor I'm going to term the Solid Base Diameter. Let's define that: Solid Base Diameter is the minimum distance across tip of a spear where the impact energy is within 5% of maximum. That is, if you were to hit somebody, it's the size object they would feel like was hitting them. The spear impact will transfer energy to the target just like an object of that particular size.

Example: You build a spear the old-fashioned way. The SBD is 1.3~1.8", thanks to the bandshop core and some additional support near the core due to the stiffness of bluefoam (depends on taping method). Getting stabbed with this spear is like getting hit with a 1.5" diameter object that has been slowed down some percent based on the padding on top of the spear.
If, instead, you build a spear from my tutorial, you end up with an SBD of about 2.2". Getting stabbed with this spear is like getting hit with a 2.2" diameter object slowed some percent due to tip padding, with a commensurately lower level of pressure at the impact point.

So, as long as people are building their cores out properly, either with a base of extremely tightly compressed bluefoam cylinders or a solid base of higher-density foams (4# EVA, 6# PE) and capping them with something stiff before adding their tip padding (which should be absolutely no less than two layers of blue and a layer of 1.25" of Ensolite), these new spears are SAFER than the old kind. Technology ensures it.

However, how do we catch when they aren't being built out properly and prevent small SBD impacts to our bodies? We remain vigilant. The only good way to catch a low-pro spear with an improperly-built base is to know what they should feel like and fail them when they don't feel right. Ask the owners about the construction, too. Squish the tip hard with one palm and see if you can feel a smaller area pushing on your palm that you should. That sort of thing.

Sorry about your rib, Rocca, but I don't think increasing tip size is going to help anything. If nothing else, where does that leave swords with stabbing tips? Javelins? Stab-only daggers?

[Elebrim]

Hold on a second, Arrakis. I think you left out a necessary spear design to be considered.

You mention the SBD of 1.3-1.8" and compare it to the SBD of 2.2" to make the point that the new low-profile spears are safer. And it is true that the older foam-football-on-a-stick style spears are going to be less safe than newer tech. But the standard spear you see on an event field isn't normally of that older style. It is more along the lines of the Edhellen build of layered foam providing a circular base on which to mount the half-football of open cell. This spear would have a much larger SBD, probably of at least 6-8" that is then decelerated by the open cell padding of the half-football.

So yeah, the 2.2" is safer than the 1.3-1.8" for sure. But it's definitely not as safe as a 6-8" SBD spear. It seems to me that given this information, the trend over time for spear SBDs went from narrow to bigger (i.e. safer in most cases) and now is trending back toward the narrow. If the new tech is actually returning spear designs to a place from history where injuries were more likely, this is something we should be careful about before making low-profile spears a universal concept.



And just to add onto the point about weapon checking - It's important, but in cases like this the standard "back check" is just not sufficient. We check weapons on an area of the body which is more damage resistant and broader than other areas - and it's those other areas that are more likely to be hit. Sure, the worst offenders will get caught, but what about all those that are "eh, it's ok" or "bring it back tomorrow" that are borderline? Passing those through is extremely risky because those are the ones that are going to be the most dangerous when they target any other area on the body.

Anyone thought of spear checking on a shoulder? A calf or thigh? A stomach? That'd be a much better measure for questionable weapons.

[Arrakis]

Hold on a second, Arrakis. I think you left out a necessary spear design to be considered.

You mention the SBD of 1.3-1.8" and compare it to the SBD of 2.2" to make the point that the new low-profile spears are safer. And it is true that the older foam-football-on-a-stick style spears are going to be less safe than newer tech. But the standard spear you see on an event field isn't normally of that older style. It is more along the lines of the Edhellen build of layered foam providing a circular base on which to mount the half-football of open cell. This spear would have a much larger SBD, probably of at least 6-8" that is then decelerated by the open cell padding of the half-football.

Pretty sure you didn't really understand what I was talking about. Old-tech spears like you're talking about can be forty-five inches across and covered with a yard of open cell. They STILL have an SBD of ~1.5" because a wrap of bluefoam is never going to give you the core push-through reduction of a solid base design like Pre-Compressed Cylinders (PCC) or Solid Block.

I had no idea people ever put a football on a stick without bluefoam under it. Probably because I can't fathom an idiot with a tiny enough brain to think that that's a good idea being able to breathe and walk simultaneously. I was talking about wrapping your tip to 4" with a long strip of bluefoam, capping with two layers of bluefoam, and then adding a trimmed half-football of POOF foam. It's NOT as good a design for preventing pushthrough as a PCC or Solid Block design! It's just not! It might hit "softer" to somebody not getting mega-jacked with it, but it hits at least as hard as my 2.75" wide spear does if you hammer somebody who isn't looking.

Tell ya what. Go get one of each design and get some of that permanent deformation foam and impact-colored carbon paper that they use for impacts testing and hit that foam with both spears. I guarantee you'll have a much darker, much smaller circle in the middle of the old-tech impact than in the middle of the low-pro impact. That's the difference between low and high SBD spears. The smaller the darkest circle, the smaller the SBD. Ask Oznog if you don't believe me.

[Elebrim]

I had no idea people ever put a football on a stick without bluefoam under it. Probably because I can't fathom an idiot with a tiny enough brain to think that that's a good idea being able to breathe and walk simultaneously.

I have seen them; they exist. Just saying.

I was talking about wrapping your tip to 4" with a long strip of bluefoam, capping with two layers of bluefoam, and then adding a trimmed half-football of POOF foam. It's NOT as good a design for preventing pushthrough as a PCC or Solid Block design! It's just not! It might hit "softer" to somebody not getting mega-jacked with it, but it hits at least as hard as my 2.75" wide spear does if you hammer somebody who isn't looking.

Thanks for the clarification. I went ahead and read through both your tutorials (jav and spear) just to make sure I didn't miss anything. I would raise two points for you to consider:

One: newer tech can be integrated into older designs. While you may be comparing the two layers of blue foam on top of a Bandshoppe pole method to your PCC/solid block method, it would be simple for someone to use a PCC/solid-block design - including the leather cap - to make the older, wider method work just as well as the new for core push-through reduction.

Two: not everyone building a low-profile design will use your exact method. Think of all the people who don't troll the boards (80% of the game, arguably), see low-profile spears at an event, and then build their own without asking about physics questions or foam types used. They'll basically use the "old method" and put two blue caps on a low profile spear head.



We should segregate the ideas we're debating. Using PCC/solid block is one new piece of tech. Using a narrow profile design is new tech. We're not debating the former, but rather the latter. So assuming that all other conditions are equal, is a narrow profile design safe by comparison?

[Arrakis]

Certainly, in all likelihood, using newtech features on a 4"-wide spear head will produce a softer, comfier head. However, I contend that a 2.75"-head spear built properly with the newtech is just as safe, as far as inflicting bodily harm goes, as a newtech spear with a 3" head or a 3.5" head. I think the question here is: Can we check low-profile spears in such a way to guarantee their safety at least to the same degree as we can guarantee the safety of javelins and red weapons?

It's not traditionally been the purview of the Book of War to specify precise construction, so it may be difficult to legislate spearheads with larger SBDs and less push-through. Too, simply calling for an increase in minimum size is unlikely to solve the problem. Also, the recent (~3+ years) trend has been towards not preventing good foamsmiths from making nice weapons just because some people can't make similar weapons safely.

It's an interesting problem.

[Theros the Large]

And just to add onto the point about weapon checking - It's important, but in cases like this the standard "back check" is just not sufficient. We check weapons on an area of the body which is more damage resistant and broader than other areas - and it's those other areas that are more likely to be hit. Sure, the worst offenders will get caught, but what about all those that are "eh, it's ok" or "bring it back tomorrow" that are borderline? Passing those through is extremely risky because those are the ones that are going to be the most dangerous when they target any other area on the body.

Anyone thought of spear checking on a shoulder? A calf or thigh? A stomach? That'd be a much better measure for questionable weapons.

Weapons are checked the way they are due to the fact that the weapons checkers are not testing one weapon. They are being hit numerous times with multiple weapons for an extended period of time. Hitting weapons testers in the back is the only way to keep them from being injured from repeated strikes.

How many full power spear shots are you willing to take to the stomach or solar plexus? How about right into the tip of your knee cap? That would be a really great place to test out your theory. Too bad that you would probably be sidelined for the day, if not the entire event if any of those weapons were unsafe. Thanks for volunteering to help with weapons check, enjoy your medical bills.

I understand your point but it is just not feasible to test weapons in that fashion.

I would like to see how many genuine injuries have been caused by the new "low profile" style spears. Does anyone have any stats on that?

[bo1]

i also would like to see the applied force number that rocca is using, perhaps i am mistaken in the saftey of hydra spears, but for now i stand behind our 2 year saftey record.

as for changing the testing, better weapons checking is always a focus, and never gets any momentum. the problem is that there is no regulated way to test weapons with any mode of cost effectiveness. it would require expensive force plates and swinging machines. probibly with pneumatic pistons to change force easily.

[Azgarehta]

I just attempted to build my first low profile spear. I can tell you that using the old method of blue cylindar over bandshoppe, even with a leather cap doesn't soften the blow as much as his PCC/solid method. I put 2 layers of marine foam and a block of grey on it and the tip folded over.

The design is good, but its very advanced and has to be followed TO THE LETTER. This means that weapons checkers have to be extra vigilant with these weapons, just like they do with reds and arrows.

[varadin]

I know this may have been hit on a bit but I cant stress it enough about when checking polearms.

A heavy(hard) hit needs to not be a push. It NEEDS to be a Slaming popping motion where all the impact happens in an instance not a heavy shove forward. Checking a spear impropperly pushing people leads people to think its nice and safe and then on a true POP of a spear it bottoms out or compresses too fast and causes HUGE injuries.

The size of the spear never matters, its all in the checking.

[Satanaka]

Hmmmmm..... interesting read.

BUT- last time I was helping with weapons check at an Octoberfest- the smaller spear heads failed due to hurting. This was checked by 3 different Herlads (many years experience & different realms)
Each person looked at them and checked them and we used several different people to test them on.

That is what I know and experienced with the small headed spears.

[Elebrim]

Theros - Agreed. I wasn't arguing to change the standard factory-line check altogether, but more how to approach questionable or borderline weapons. Re-checking against the back may not clearly spot a problem.


Azagarehta - Thanks; that was basically the point I was trying to make earlier. Though there is a way to make the new designs safer, i.e. with newer methods, the design itself isn't universally safe to make any which way you slice it.

I would hate to give people the impression that this method is the new norm, then have 80% of people build it wrong and create a whole generation of unsafe spears.

[Rocca]

Hey guys - Sorry I've been out of it for so long, I haven't had a chance to read your posts. Thank you for talking about this by the way . I went to PAX (which was tons of fun) and caught some sort of evil bug, but I will try and have the numbers that I ran up by tomorrow, though by now it may be a moot point!

[Arrakis]

Hey guys - Sorry I've been out of it for so long, I haven't had a chance to read your posts. Thank you for talking about this by the way ;). I went to PAX (which was tons of fun) and caught some sort of evil bug, but I will try and have the numbers that I ran up by tomorrow, though by now it may be a moot point!

UNNNGHHHH DID YOU GET TO PLAY THE DUKE NUKEM FOREVER DEMO?


Also, I don't know if I made it sufficiently clear that I believe that low-profile designs should really only be undertaken by truly competent and advanced foamsmiths. I wasn't even going to wiki my design for at least another year or so, but other low-pro designs started appearing and I wanted to get what I consider "the best way" to do it out there for people.

[Azgarehta]

I will say that the tutorial and instructions are top notch. I've only got a year and a half into the sport, and have only built a handful of weapons. It'll take me another year or two worth of foamsmithing to get all the concepts down and make a low profile.

[Rocca]

UNNNGHHHH DID YOU GET TO PLAY THE DUKE NUKEM FOREVER DEMO?

No, I didn't wait in the line . I saw some of it being played though. Looks like a pretty cool game. Also, you totally should get NBA Jam if you have a Wii- that game is the ****.

Now, for an incredibly long post involving numbers. I have tried to lay everything out as I was looking at it. I also had some numbers about crash's and impacts and average force applied to cause injury etc. from autopsy reports but my computer restarted so I will have to search the internet again (my history cleared so I can't just go back). But here are the numbers that I was using.

...............................................
So, the numbers I ran are sort of taken from this thread on this martial arts forum: http://www.martialtalk.com/forum/showthread.php?t=16026

Velocity of the fist = displacement of the fist / time required to complete the displacement

Acceleration of the fist = change in velocity of the fist / time required to achieve the final velocity.

Force of the fist = mass of the fist (including arm and some of torso) x acceleration of the fist. As it applies to the punch, force is of no concern if it misses the chin. If it strikes the chin, then an important consideration is the amount of pressure the fist applies to the chin.

Pressure of the punch = force of the fist / striking area of the fist. Thus the smaller the striking area of the fist, such as the first two knuckles versus the entire front of the fist, the greater striking force.
I don’t actually know the mass of a spear. I don’t currently have any on hand so I am taking the shipping weight from Edhellen (6lbs) as a max figure and then going with what I think it normally is, around 4lbs. For the low profile ones, I have no idea so it would be nice for someone to get the data so I can plug that in. Also, I am ignoring the “arm and torso” part of this equation, because since we are comparing spears just on the impact site size, the torso part would remain the same so can be cancelled out.
Mass of spear: 2.7216kg (6lb spear)
1.8144kg (4lbs spear)

Acceleration of spear(?):
I couldn’t find any numbers that simulated a spear thrust, so I went with punch data found online. An average spear thrust, since it has two hands, should be something like a punch right? So, if we assume it is THE SAME as a punch, here are the numbers I found. http://www.fileguru.com/Knockouter-Punc ... Meter/info
Ricky Hatton’s max velocity (left hook): 51km/h (14.2m/s), average: 40km/h (11.1m/s),
So, let’s say that’s the max velocity shall we? How long does it take a spear user to get to that speed? (technically, it’s the deceleration of the body that actually dictates how much pressure is applied at the end of the thrust, but the numbers here are for a body that doesn’t move at all, so they will be over the top.) After timing some spear thrusts, (both from online videos and from test myself) it takes between .3 and .6 seconds to get the trust in. This means that, the acceleration of a “max velocity” strike is between 47.3m/s/s and 23.7m/s/s and the acceleration of an average velocity strike is between 37m/s/s and 18.5m/s/s.
Force of Spear: mass x acceleration= force in newtons
Force, 6lbs spear:
Max strike max: 2.7216kg x 47.3m/s/s = 128.7n
Max strike min: 2.7216kg x 23.7m/s/s = 64.50n
Average strike max: 2.7216kg x 37m/s/s = 100.7n
Average strike min: 2.7216kg x 18.5m/s/s = 50.3n
Force , 4lbs spear:
Max strike max: 1.8144kg x 47.3m/s/s = 85.82
Max strike min: 1.8144kg x 23.7m/s/s = 43.00
Average strike max: 1.8144kg x 37m/s/s = 67.1n
Average strike min: 1.8144kg x 18.5m/s/s = 33.6n

So, now to the real question: How does dramatically does the pressure of the spear change with the smaller surface area?
We have so far seen that the force of a 6 lbs spear is between 50.3 (total min) and 128.7 (total max). No low profile spear is this heavy, so we can basically only used the 4lbs numbers. (which I am only now realizing . . . why did I do all of that extra math! ). So the 4lbs strkes vary from 33.6n -67.1n and 43.0n-85.82n. What is the difference in pressure if there are to spears, one with a 5 inch head and one with a 2.5 inch head, that are the same weight?
Pressure=force/striking area.
5 inch spear: (Surface area of 0.4m2)
Maxmax pressure: 85.82/ 0.4m2 = 214.55 pascals
Maxmin pressure: 43.0n/ 0.4m2= 107.5 pascals
Averagemax pressure : 67.1n/ 0.4m2= 167.8 pascals
Averagemin pressure : 33.6n/ 0.4m2= 84 pascals
2.5 inch spear : (Surface area of 0.2m2)
Maxmax pressure: 85.82/ 0.2m2 = 429.1 pascals
Maxmin pressure: 43.0n/ 0.2m2= 215 pascals
Averagemax pressure : 67.1n/ 0.2m2= 335.5 pascals
Averagemin pressure : 33.6n/ 0.2m2= 168 pascals
So, as one would expect, when the surface area is halved, the applied pressure doubles.
………………………………………………….

So, those are the numbers I was running. These numbers are a simple doubling of the force however these numbers do not taking into account the actual pressure of the impact when the body gets hit. The deceleration of the spear when it hits the body differs with different amounts of foam and surface area.
Additionally, I had some autopsy reports and some medical papers about thoracic trauma that went into detail about the different types of “penetrating” impacts that different surface area’s had on the thoracic area. My computer restarted so I will have to find them again, but what it comes down to it a smaller area of impact breaks the natural elasticity of the thoracic area (which is the most elastic part of the body). This is why getting hit by a baseball at the same pressure can break a rib where getting hit by a board with the same pressure wont (something about elasticity of ligaments on rib cage . . . I will try and find it.)

*phewh* . . .

That was a long post. Sorry about the length, but those are the numbers. I am sure some of you have a better handle on this then I do, but that’s what I was looking at. Also, I think the discussion about the way we check spears is important – that may be the key, if the surface area is not.

[Arrakis]

...
What is the difference in pressure if there are to spears, one with a 5 inch head and one with a 2.5 inch head, that are the same weight?
Pressure=force/striking area.
5 inch spear: (Surface area of 0.4m2)
Maxmax pressure: 85.82/ 0.4m2 = 214.55 pascals
Maxmin pressure: 43.0n/ 0.4m2= 107.5 pascals
Averagemax pressure : 67.1n/ 0.4m2= 167.8 pascals
Averagemin pressure : 33.6n/ 0.4m2= 84 pascals
2.5 inch spear : (Surface area of 0.2m2)
Maxmax pressure: 85.82/ 0.2m2 = 429.1 pascals
Maxmin pressure: 43.0n/ 0.2m2= 215 pascals
Averagemax pressure : 67.1n/ 0.2m2= 335.5 pascals
Averagemin pressure : 33.6n/ 0.2m2= 168 pascals
So, as one would expect, when the surface area is halved, the applied pressure doubles.

The only problem with this particular set of calculations is here. Listing assumptions for any given operation, as I will be telling my physics students this year, is always a good way to catch problems. Here, the chief assumptions are a) that the mass of the spear is the only mass contributing to the force of the blow and b) that the easily measureable frontal surface area of the spear is the actual impact area as far as distributing force is concerned.

That factor, the "Effective Area" is closely related to SBD (solid base diameter, which I talk about above). For an old-tech spear with a tapered head that goes from 3" across to 5" across at the slope of the POOF Football that makes up most of its head, the effective area is probably something like 2.5", being generous with the self-support characteristics of a generously assumed 3 layers of blue under the POOF. For an Arrakis-design lo-pro spear, it's something like 2.3-2.5" (almost the whole width of the spearhead). So, assuming the same weights, the difference in impact pressure between a 2.5" EA old-tech and a 2.2" EA new-tech (pessimistic estimate) is a ~1.3x higher impact pressure for the lo-pro.

But! My lo-pro, at 87" (7'3") on bandshop, weighs 33oz (2#1oz). An oldie on 1.25" PVC weighs a lot more than that, but I don't know how much more and I don't know how much an oldie on bandpole weighs. So, there's the weight difference, too.

-----------

Then, there's the fact that the forces we really need to measure are the impact forces applied to the body. That means knowing the time it takes during a spear impact for the velocity of the thrust to fully stop (the de-acceleration time). That times the effective mass of the spear divided by the effective area of the impact will give us effective applied impact force. Otherwise, we can use de-acceleration time and your original force calculation to determine applied impulse, which could also be a useful measure, perhaps.

Anyway, the things that makes a weapon feel like it hits too hard are a) padding insufficiently stiff and thick, bottoms out and allows core to be felt through the strike (i.e., using open cell over a core, too little padding, etc.), b) padding does not adequately lengthen the de-acceleration time of the shot, causing a higher amount of force to be transferred to the body (i.e., foam too stiff, too much tape, etc.). Of course, the wider the effective impact area (similarly, SBD), the easier it is to achieve sufficient padding so that a) doesn't occur. That's why a questionable old-tech can hit great on Light and Medium and really hurt on Hard while a properly made Arrakistech will hit identically on all three strikes with the only factor changing being amount of pushed-over-ness.

Anyway, yeah, the things that could make a new tech low-pro spear hit too hard are primarily: 1) Too little padding (I recommend at least 7/8" of ~2# foam like bluefoam and at least 1 5/8 of ensolite) over the effective tip of the core and 2) too small an SBD. You'll notice that reason 1) here is caused by b) above and reason 2) here is caused by a) above. So, Yeah, I don't know. Make sure there's plenty of squish on any spears you pass, makes 100% certain you can't feel ANYTHING REMOTELY like core push and then make sure it hits good and feels like it's at least almost as wide as it is when it hits you.

*shrug* /long post




tl;dr: Herp derp math and spears, don't make a spear under 4" in diameter unless you know what you're doing, and even then, you should probably use the methods I use in my wiki article to make your spear safer.

[Forkbeard]

Here's my experience.
I have limited my spear heads to 3" I use the denser then softer eva stack design with a little nerf foam on the end.
I think they would be safe at 2.5", but I make them 3" so they always pass, and they do. Nobody eve3ry get's hurt, or complains overmuch.
Rhinos low-pro spear at chaos was cool.
The one made by the guy from Ered Duath, however, sucked monkey *. It nearly tore my face off.
The way I see it, spears are one of the weapons that people mostly feel are lame, safe weapons to hand to new people. Sometimes they are in the hands of good spearmen who can really hurt people one handed if they want to.
The way to make you spears last and always pass is to make them to balance between "ultimate rubber weapon" and good, safe and longlasting. It keep everybody happy and keeps the heralds off your back when somebody is dry heaving on the ground from your lovin.
FB

[bo1]

thank you rocca for posting all that. it is good work and i do enjoy your opinion on the matter. i disagree with you, but dont think that i dont respect your opinion.

arrakis i new you would see the same problem i did with the math. i know for a fact that my spears are lighter than any old tech giant poof. that and the mechanic of being stabbed is so very significant in generating force. the actaul force of a stab varies greatly.

but even with all this, i have no problem with going to a 3" minimum for greens longer than 6 feet. that way all the min reds dont need to me modified. but this will likely not go anywhere, with your equation, a 3" vs a 2.5" is like 10% change in force, not very significant.

[Forkbeard]

I also would support a change to 3" on weapons over 6' long. But I'd rather seen more instructions and encouragement bent toward people just making them like that on thier own.
Very, very few people can make them under 3" and have them pass consistently. The difference in force is negliable, but the lifespan of the weapon is affected greatly unless the builder really did their job. One of the great things about a spear is a good one last about for **** ever. I have every confidence my 3" spearheads will last 10 years.
I think popular culture can do alot of good here.
FB

[Slagar]

Sometimes, I freaking love these boards. This was cool to read. Thanks for taking the time to post.

Now who wants to make/sell me a high-tech lo-pro 8 footer?

[Azgarehta]

Yes, I'd be on board for the 3" ruling for spearheads. Makes them hit less hard, last longer, and gives a little extra room for non-scientist weapon builders to be able to make a safe weapon.

[Slagar]

See, the problem there is that you're legislating construction methods, and crippling the advancements made by the experts. If somebody can make a safe, passing, lo-pro spear, then to outlaw it is pretty stupid.

We start making rules against certain builds just because some people * 'em up, the level of weapon-making in our game goes downhill pretty quick. This problem is handled at check, same as all the other ones like it. If you are a little wary of lo-pro spears, test all 5-10 of them at any given event extra thoroughly. Pass or fail them on their own merits. Creating a blanket rule like this causes weapon tech to stagnate in the long run, and is just plain unnecessary.

[Poo]

See, the problem there is that you're legislating construction methods, and crippling the advancements made by the experts. If somebody can make a safe, passing, lo-pro spear, then to outlaw it is pretty stupid.

We start making rules against certain builds just because some people * 'em up, the level of weapon-making in our game goes downhill pretty quick. This problem is handled at check, same as all the other ones like it. If you are a little wary of lo-pro spears, test all 5-10 of them at any given event extra thoroughly. Pass or fail them on their own merits. Creating a blanket rule like this causes weapon tech to stagnate in the long run, and is just plain unnecessary.

QFT. Don't be fascists.

[Arrakis]

Next Northern event I'm at (probably either late summer '11 or later, ugh), I'd be very happy to build one of my spears in person for anyone who wants to see the process. I'd just need someone to donate a stick of bamboo or bandshop and someone to either handsew a cover for it or let me use their sewing machine for a few minutes. I'd probably even sell it cheap to whoever donates the core.

[Poo]

I have a bandpole spear that needs to be redone, i'll strip it and bring it if this is a sure thing. Lemme know about pricing.

[Rocca]

Hey guys -

I'm back from a 10 day internet hiatus. Thanks for discussing this in so much depth. It seems to me that, while I still think a rule change would be good and no more limiting than the 2.5inch rule currently is to experimentation, the key for these low profile things is PERFECT construction methods. I don't know how we can emphasize that for new foamsmiths (we've all met one that thinks that their **** first blue is awesome and now that they've made that they're gonna make a scythe ) but if we could emphasize it it seems like a good idea. Also, earlier people were talking about how to check spears properly. Do we have a written down version of the checking guidelines? I learned to check in person from someone else, and honestly still hone my skills at larger events, but if someone is from way out in nowhereland they wouldn't know how to do it and do it RIGHT. Anyone know if we've got something like that?

[Isk]

I am coming late to the discussion here, but wanted to chime in and first underscore Arrakis' emphasis on the importance of the SBD. You see this in Oznog's research with arrows as well and it applies to javs and pretty much all stabbing weapons which strike with a much smaller surface area. The solid base diameter is the area that spreads the force of the impact. This is why Dag adopted their new rules about the base size for javelins and arrows. A solidly built base that will evenly distribute the thrust is THE key to making a safe spear/javelin/arrow/stabbing weapon. I don't think that can be overemphasized.

With the discussion of changing the minimum diameter I also wanted to bring up one point that has only been lightly touched on and that is javelins. I don't see any reason why a 6 or 7 foot javelin (yes it's difficult to make a passing, durable 7 foot jav, but it's legal) would be treated any differently than a spear for this discussion. I agree most strongly with what has been said regarding proper weapons checking and personally I would really rather not see the rules changed so that javelins are any bulkier than they already are. If anything I'd prefer to see the max weight reduced for javelins, not the head size increased. Checking should, as has been stated, include careful attention to whether the head is pushing through in the center or whether an appropriate SBD is in place and the pressure is well spread across the face. Checking really needs to be taught in person, at an event. Until the nowhereville folks come into the fold by attending events and learning to check there, they will be out of touch with Bel no matter what is written down. That said, I have used this guide on geddon to help my guys get the idea.

I feel with good weapons check the newer, low-profile designs are as safe as the couch-cushion or poof spears as big as your head. Honestly, I would prefer to be stabbed by my 2.75" low-profile spears than a couple of the monster spears I have met.

[Azgarehta]

I'd like to get a rundown from Arrakis or one of the other spear experts on what things to go through to determine a good vs. bad build of a low profile in weapons check. Also, what should we be looking for on one that is breaking down? Tip fold? Sweet Spots? Obviously hit test is going to be the main deciding factor. With larger spears you feel that pressure and push, the low profile I made has more of a pop to it.

[Poo]

If your low profile spear is folding, i'd rebuild it. One of the things i love about low profile spears is that, with how i make them, i can use scraps, and it takes a very short amount of time. I rebuild my spears pretty often to keep them safe.

[Elebrim]

Brief tangent: Just had my point about 80%+ of the game not being online proven at Equinox. I helped check and failed a new fighter's low-profile spear that he had built after hearing about the design from fellow unit members who had been out to more events. It hit way too hard. I gave him construction advice after the fact and recommended that look up different instruction guides online, but he had never been online apart from his own web board and hadn't heard of any of these resources to begin with.

Thought that story was applicable. You may now return to the conversation.

[Sir Par]

And I did the stabbing! The spear failed on the medium hit, and from the look on Elebrim's face it was pretty brutal.

[Elebrim]

Yes, that was you, wasn't it? It was great sparring with you on Saturday, by the way.