There are some complicated dynamics at work that can be difficult to untangle due to the stroke having almost as much influence on the cut in practice. I've done a lot of work studying the balance of axes, scythes, and other asymmetrical tools, including machetes, swords, cleavers, and so on. Presentation of the cutting line, mass distribution, and the spatial positioning of the edge relative to the range of motion of the stroke, as well as other factors, will compound to contribute to cutting performance. Isolating the edge forwards of the hand alone without an overall increase in blade mass, as in a khopesh, mostly influences the point at which the edge meets the target, allowing for greater impulse and follow-through at the expense of reducing the distance over which you are able to accelerate the weapon before impact. Would love to chat more about it but it's much more than I can cover in a RUclips comment.
Good comment though. Well stated. Favor the khukuri for chopping, but just bought a khopesh to compare that exact thing, mass at point of impact versus swing efficiency. Interesting topic, to be sure...
@@FerociousSniper I've given lectures on the subject but don't have any blog posts on it currently, I'm afraid. Apologies for the re-post. I accidentally sent one from my gaming channel 😅
I think also regards to your chopping theorem, its important that youre contacting earlier in the arc of your powerstroke and can exert more force over a longer time on what you're cutting
I absolutely think you're right about wrist angle being a part of it. And it'd also be interesting for you to revisit the Indian hilts on backwards curved blades that also "lock in" one's wrist and see if you feel (literally 😏) that the same benefit applies.
I chop wood with a parang and the blade being slightly forward of my wrist does make a lot of sense, keeping a stronger wrist makes it feel like I don't need to put as much effort in
When I used to help my brother-in-law chop wood, I got to use an axe that had a larger head than I was used to, and it did feel more 'right'. I put it down to just feeling a little safer with slightly more distance between my hand and the impact, but it was just a feeling.
Agree, Although there are backward curving parang designs too, the forward curving ones feels much better in the hand. It gives that satisfying bite feel to it when it hits the target.
Forward curved swords like a Falcata, Yataghan, Kukri and even Falx amongst other styles definitely cut way better IMO. Single edged sword's also have the mass of the spine directly behind it. The forward balance of some those swords helps. I love them, and think Sabres to Katanas are over rated. Let us bother Matt or Skall to commission a two handed yataghan. Love them. What is the proper name for that first sword he brought up? Yatagahn? Oh and draw cuts can be vicious as they kind of catch, and digs deeper as it drags.
I think your idea of wrist angle is valid. I have done extensive land clearing with both a straight machete and a kukrhi. Even with the machete being lighter and longer, I don't feel as tired when using the kukrhi. It also feels more powerful. Look forward to whatever testing you can do.
Amen to that. Used a khukuri to clear a firebreak lane, could not believe how easy it was compared to other tools I have used. Less fatigueing grip, letting it just rock in the hand, movwing through even two inch branches and vines in a couple chops. Almost as fast literally as the guts with chainsaws next to me. Totally convinced me of the difference in blade geometry for specific applications.
Feel free to correct me, but I believe having the forward curved blade puts the center of gravity forward as well. Mixed with wrist position, this would allow for more/easier penetration with chops.
As a blacksmith, I want my wrist to be pretty square when I strike like how you described with the forward curved blades and axes. Also as a blacksmith, forward curved blades Are harder to make, and sharpen lol.
Hi, Mat. I like forward curving blades. Here's a couple of ideas on why it's better; 1 ▪Forward Power Projection Ie like punches delivered in many traditional martial arts forms, you don't actually aim to hit the object you're targeting, but actually a bit of a distant behind it. Hence, a punch to the face isn't aimed at the face, but a distant beyond the face. So you're in essence punching through. Hence, the power projection is greater at the point of impact. A forward curving blade brings about the same effect as the the "feel" of the aim is "at the wrist". But the the impact of the forward curvature arrives first. Hence the wielder of the blade has the tendency to continue the drive forward until he feels the wrist has actually arrived at the blade. This driving through projects alot more power and hence, cutting action at the point of impact. Just like a traditional martial arts punch or strike. 2. Modified Drawing Cut Asian swordfighting techniques used alot of the drawing cut technique. For forward curving blade, the initial cut, which hacks through the target, is then followed by a drawing action. Ie the drawing of the blade to initiate its released from the body. Since the blade is forward curved, the wielder needs to only pull the blade in a straight back lateral draw as opposed to a more curved draw for a backward curving blade. The forward curving blade acts like a hook, to sort of hold the body and keep it in place. Even if the body were to fall backward, the fall of the body would still allow for the cut to take place. A rear curving blade in comparison will have the body falling away from the blade. This hooking effect, creates a longer contact to enhance the slicing action. I've tried this out using ripe papayas on my antique South East Asian, forward angled Moro Kerises and Sumatran Badeks. Welcomed comments from fellow enthusiasts here as I'm keen to expand my knowledge too.
Might be a fun and enlightening collab with Tod (along the lines of the "Weird historicals" series) for him to try making a reasonable forward-curving/forward-projecting blade that *isn't* a good cutter. Seeing why one doesn't work could help to pin down why most of them do work.
I've loved forward curving blades because of their aggressive aesthetic, their traditionally believed superiority as choppers, and because depending on the shape of the tip they can even give a stronger wrist alignment when thrusting, akin to a pistol grip. So yeah, I'd love to see more info quantifying the performance of such blades in chopping. However, my love for forward curving blades has forced me to come to terms with the seemingly far greater popularity of backward curves on curved blades. Which begs the question of why they're so much more popular. I suspect that a big part of it is that given the ubiquity of shields through most of history, the utility of a backward curved blade in delivering underhand and backhand pokes under, over, or around a shield was extremely useful. I feel like the popularity of cat's claw tips is additional evidence of this. Add to that the ability of a backward curving blade to give very long cuts, potentially with much of the length of the blade and that's probably the reason that form factor is so popular.
As a fellow fan of forward curving blades, I have also thought about this. I tend to think it’s much more to do with slicing length versus chopping power. I actually feel like a forward curved blade might be better suited for poking around shields than a backwards curved blade.
@@spleenjacobson203 As for some examples for weapons that are useful vs shields are the egyptian khopesh or the scythian/thracian/persian sagaris. In later periods where the sword becomes a 100% side weapon, these traits are found in polearm weapons like the various chinese Ji or Ge variations & the scythia/Crimean great axe (medieval two-handed weapon, similar to danish longaxe but usually longer, uses a Π blade to reduce weight and be nimble, in general big axes were favored in Crimea region). Shield walls in the dark ages were very common and the danish longaxe & the scythian great axe (also used by the sarmatians/alans) was used for that reason by the Varangian mercenaries (Norse, Rus, Saxon or Anglosaxon origin) of the Eastern Roman Empire against tired foes to completely rout them. As for the Ji/Ge it become just like the Halberd, especially as armor use was reduced. Egyptians primarily used maxes and spears if they didnt use missile weapons.
Thank you!!! I've never see sword videos that mention DRAWING the blade. Never thought of hitting at an angle would effectively narrow the edge - THANK YOU!!!
Sooo refreshing! It helps me in pulling myself together and finding a solid ground underneath my feet. Thank you. Greetings from Prague, Czech Republic.
From physics point of view the length of the effective lever is increased by placing the striking part in front of the handle which in turn increases the torque and thus speed and power. However the effect seems quite minor unless some very strong forward curve. Your axe for example would only get around 4% increase in toque (applied pythagoras' law and thought of the axe head and shaft as the legs of a right triangle and the effective lever as the hypotenuse and measured lengths by eye). The Problem with this idea is that increasing the length of the weapon would do the same thing and also increase reach.
Last point very good. Extends well into a general point about biomechanics. You want to hit your target at the point where 2 conditions are jointly maximised. 1. Acceleration of cutting edge. This maximises the force of the cut, past this point the blade slows. 2. Stiffness of body. By this I mean that you lose less energy on impact, the more your body gives, the less force is transferred to the target. So its not just having your wrist in a strong position, it is your entire body. To take your axe analogy, image in the head a few inches behind the handle and you are aiming to hit a targey a few feet in front of you. Generally speaking your swing is already finished upon the hit, there are fewer muscles in an optimal position. Finally, in prsctical terms, if you want to biomechancially put yourself in a better position to cut, you have to compromise by shifting your centre of balance more - which leaves openings. So you need to consider being able to cut well from more angles, without swinging wildly is just as important as the cut itself. Source: pure speculation.
I have realized that I have had quite a lot of problems with wrist extensions while using straight weapons (while training kali). This video was very helpful for how I can work this into future weapons! I appreciate it! ✨
The relationship between the angle of attack and edge geometry, and the strength vs wrist position concept are news to me. It's fun to learn something new.
I personaly think it might be a biomechinacal reason. Your wrist isn't that strong of a point in your body. In many positions it's just weak and will easly be overpowerd. Sow having your wrist bent into a cut will dempen the blow. There is how ever a position in which you can lock your wrist to such a degree that it's a rather strong point that's very unlikely to move. That's when you make a fist. Things that have the hitting portion infront are more likely to hit when your still making a fist aka the blow isn't dempining much and your able to maintain much more power from your strike. Sow I think it has to do with how the weapon functions in relation to the body and not with anything related to the weapon it's self.
A bunch of people (including Matt in the video) have already said the thing about wrist position but I just thought I'd add a few additional thoughts on that same thing. 1. Instead of phrasing it as wrist position you can also think of it as the angle my arm must be it (for the same wrist position), this can be a useful way to veiw it too (I think) given how powerful the muscles of the wrist vs the arm are. 2. I believe that elbow muscles are significantly more powerful when the elbow is in a bent position. There are atleast a few potential biological reasons for this like where exactly the attachment points are on the forearm bones, how the muscles' deformation impacts the positioning of and forces acting upon the individual strands and acting proteins in the muscle fibres, the impact of them having to stretch of their complementary muscles (especially if all your muscles are a bit tense cus you might die). 3. The forwards curve may sometimes be essentially necessary to reach a place at all. If I imagine trying to cut upwards into the inside of someone's thigh or groin or up into their armpit the angle of my arm is such that, short of kneeling down, a straight blade just isn't really going to connect. At best it'll hit them mostly front on, which may be useless if I was targetting that point specifically to exploit the common lack of armour there. I also think that it could be interesting to explore the positioning of different thrusts with different shaped blades because a forwards curve facilitates thrusts more directly in line with your forearm, potentially making them more powerful thrusts but also restricting the arm position they can be made from. While a straight blade allows thrusts to be performed up from a low arm position, and lets your wrist-sword joint form a significant angle allowing to thrusts around objects.
This may be difficult to explain, but watching the motion of the blades I can see it: the ace is easiest to see: the point of the forward curve (on the axe where the head protrudes forward from the shaft) becomes a second fulcrum. At the point in the swing where impact would occur, the edge begins to also swing in an arc simultaneously down AND toward the person swinging. All fulcrums in moving in this swing have longer levers behind them, so they are increasing the force in the smaller arc swinging back toward the cutter as well. It’s essentially a “compound blade” at that point.
I think you are on the right track with th extended wrist theory. Whenever hitting a target, it is important to be in a strng position to be able to put one's entire body's strength to the highest possible degree behind that position. It allows for powerful hits, sturdy blocks and strong defense against disarm attempts, or against pushes into the weapon after it being blocked. Simply put, with the wrist not fully extended, the wrist is way more braced against vibrations coming back to the hand from the hit. That really does sound like the most likely explanation for why these blades feel like they cut better. For a very similar reason, very rattly handle feels feeble and very unpleasant to use and cut with.
Your comment, at the 10:00 mark, about wrist angle, is I think the answer. A comparison of a modern double-bitted axe (straight grip coaxial with the straight handle, used in logging) and a modern single-bitted axe with a curved grip area supports this. The single-bitted axe is more comfortable to use. A double-bitted axe with a single-bitted axe handle would be pointless. Splitting mauls usually have straight handles, but they rely much more on the weight of the head than axes do. Note that the single-bitted axe geometry falls in the middle of the range of the weapons you displayed (kukri, sosun pattah), although the sosun pattah you display seems to be of a much less curved variety. Most of the ones I've seen have a continuous curve along the back edge from guard to tip.
An addition to the point about the wrist angle. If the point of impact is ahead of the lever and your wrist is straight, that means your body is still accelerating the lever at the moment of impact compared to a straight blade where you will physically start to deaccelerate the lever to either avoid over extension, over balancing or to change the direction of the blade into recovery, and just like a compression spring has the least amount of power at full extension, the same is true for our joints and muscles, their effect is the most powerful half way between full extension and full contraction.
I always figured one reason why curved blades (both backwards and forwards) tend to cut better is because the energy from the impact is focused on a smaller surface area on the target than it typically would be with a straight blade. It becomes a little bit more like a point as opposed to a line, or rather a shorter line as opposed to a longer line.
*Look at airplane wings and drag.* *As I said in Shad's video, I always thought it had to do with aerodynamics.* For those who don't know / forgot, drag is the resisting force pushing against an object in motion in fluid mechanics. The shape of an object collects a certain amount of drag when moving through the air, and we know curves cut through the air better and more efficiently than straight angles and boxes. It's one reason why economical cars have so many curves and box trucks can be such gas guzzlers. The nature in which airplanes (aeroplanes) fly changes dramatically when you fit it with straight wings versus swept and curved wings, even when nothing else about the aircraft is altered. Planes with fat, wide, long, rectangular wings are more often designed for long loiter time (hanging out over a target in the air), generally increasing lift and resisting tendencies to adjustments from the environment. However, this shape actually slows down the airplane, or at least limits it's speed capacity, with greater drag. Wings that are swept-wing (curved or angled) can cut through the air faster while using less power. The shape changes the aerodynamic center, increase Mach-number capability by delaying to a higher speed the effects of compressibility (abrupt changes in the density of the airflow), e.g. combat aircraft, airliners and business jets, and reduces bending moments under high g-loadings. Flying wing design aircraft have _the_ lowest drag problems, but have the most trouble maintaining balance and control. . It stands to reason that a straight blade incurs more drag than a curved sword does. You might be able to test this by putting swords in wind tunnels.
I have a repro two banded muzzle loading musket made in England years ago by Parker Hale. I got an original Enfield bayonet for it. It has that Yadzighan (? Spelling) blade. This narrative gives it an additional purpose. Thank you.
Don't threaten me with an hour(s) long video of epic backyard cutting with dozens of swords! Because I will make popcorn and watch that. Maybe twice just to teach you a lesson.
I think it comes down to leverage and force concentration. The longer the distance of the lever (your arm + the blade) for your strike, the greater the force at the end, and the sturdier the lever (being able to keep the wrist locked while also reaching outwards with a forward-curved blade) translates to greater follow-through on impact in an ideal scenario. Then you have the nature of the edge like you noted 'pushing' forward in the cut, great for vulnerable targets like arms would easily be fully within this cutting area and get the fullest effect from the 'push' of the cutting motion when it impacts, creating greater cleaving effect. Finally, the edge contacts a smaller amount of the target at first and dramatically widens its area of contact to spend that momentum rapidly.
Mr. Easton, you should add a part to explain this with a farm or garden sickle or billhook, because more people have sickles or billhook at home. They have a long history and are common throughout the world. Of course you also know that such agricultural tools were used as weapons. However, Like sickles and axes, the sheaths of forward curved blades are more difficult to make.
If you look at civilian utility axes, the end of the handle usually curves forward to enhance the degree to which the blade is "forward". I think it's simply a matter of getting a better extension of your arm, while keeping your wrist angle natural. This has a couple important effects: 1) This practically eliminates wrist effort and fatigue, as the ax simply "holds itself" outward due to centrifugal force. You aren't exerting any wrist torque controlling the handle angle. This is important because your wrist muscles are weak, with little leverage, compared to your other arm/back muscles. 2) It provides the best distance from your elbow to the ax head. The handle and arm are practically straight. Besides the obvious safety aspect of keeping that further away from you, it simply provides a lot more impact velocity for a given amount of arm swing angular velocity. The bottom line is that more kinetic energy is in the ax head and less kinetic energy is "wasted" in swinging your own arm around. There's also something of a trebuchet-like "whip" effect, which has the effect of transferring kinetic energy from the swing arm to the ax head. The rotation of the ax itself "whips" the ax head forward while simultaneously slowing your arm. This only works if your wrist is somewhat "limp", but if your wrist is bent almost as far as it can go, then it will be resisting the ax handle's rotation rather than flowing with it.
I think both the momentum of the thing moving forwards is a factor, and I would also mention (many other people are bringing up biomechanics points) that it would change how you need to rotate and which muscles you need to exert. With a back-curved blade with longer strokes I feel the need to control for a long time through the strike and use up my arm muscles a lot, with more forwards-curves needing a lot more exertion early on from the fingers, especially the pinky, but then the momentum essentially takes over. So it makes sense for short weapons, especially ones that wouldnt do much damage without more chopping in, not having much bladeage (a word?) to shear with or acceleration at the tip. I would also add that back-curves shorten your reach (at natural arm extension the centre of percussion still hasn't reached the target, so the cut has to be pulled for longer, and with the arm muscles), so curving them forwards (getting the angle of attack benefit from a curved blade) and then recurving back brings the point back on line and restores your reach, at the cost of control during the actual stroke (if it's very short that's minor). I do think that non-recurved forwards-curves, eg. the Japanese forwards-curved Katana, dont make much sense, the risk of getting an enemy stuck in the middle of it would suck. Even Kukris recurve slightly. The Katana takes this to the extreme in that the whole thing is a banana, ie the handle continues the curve of the blade backwards. To the extent that's deliberate and they actually thought about it, it'll have the effect, assuming I'm right, of maximising reliance on the skill of the swordsman and relying entirely on the muscles (obviously it still has *some* momentum) rather than a "fire-and-forget" power stroke.
I might be completely wrong about this analogy, but when you thrust with a longer spear, a smaller movement of your arm(s) means a more impactful thrust because there's length moving at once behind the point. I feel like the same might be true of forward-curving blades and axes, where even that slight protrusion means that, for a brief moment, all the energy put into the swing of the entire weapon rests on whatever it hits before your arm goes past the target. Just in instinctual thing.
I think the wrist position is a longer conversation, because it also means the rest of your arm is in a different position, and also it means the blade will impact during a different point in it's pendulum motion. I want to imagine an analogy of the bucket of water being swung around the body to hold the water in the bucket. I also want to imagine an analogy of stability between balancing a stick above your hand, vs. allowing it to hang. (prop plane vs. fighter jet). When propellers are designed for steady speed, they are long and straight, when propellers are designed for heavy load (boat props) they curve back hard and are short. When propellers are designed for rapid acceleration and deceleration, they are also steeply curved and shorter. Hydraulic joints are another place where an offset can result in a leverage advantage or stability advantage.
I agreed on the way it works like a woodaxes, which is also for meat knife, to prevent blades stuck on target, wood or bone just by rotate it upward from wrist, the blade are easy to release from stuck positions.
I don't know mathematically why, but consider the earliest chopping tools the hand axe. It is held with the blade preceding the arm out of the fist. It focuses the energy of the basic primate overarm blow and doesn't break its efficient body mechanics. Chopping (not slicing) with one that trails the hand will put extra stress on the grip while delivering less impact since it comes past the point of optimal energy transfer for the motion.
I picked up a Bushmanster (United Cutlery) knife described as a Kukri with a 12" blade. Howiever the back of the blade is fairly straight since it has a sawback. I wnated this as a bush knife that could cut materials more sturdy than would be vulnerable to a machete. Here in New England most of our large bushes have woody stems. The blade is made of aus-6 stainless steel HRC 55-58
As many will know, in all martial arts, a strike is more effective when it is focussed behind the target, as the blow is still getting forward momentum after it hits, so rather than the power being at it's peak when the wrist is fully extended, the push continues and allows the blade to be withdrawn faster for another blow before the wrist is at its weakest point.
I think the wrist angle is just one of several factors that all combine to mean more mass (both that of the tool and of the wielder) and thus more energy brought to bear behind the edge more directly at the moment of contact. Specific technique is a huge variable, but the mass with a backward curved blade is more inclined to lead the point of impact so that the energy delivery is more drawn out with the follow-through. A straight blade then has poorer energy transfer at the point of contact than the forward swept blade and than the backward swept blade in the follow through, but can more readily mimic (to a degree) the effect of either through adjustments to technique.
Weird little thing that I dont know if people really consider... When I was training martial arts, part of what I was taught when say for example throwing a strike at someone's face... Don't try to punch their face, try to punch through it, envision punching the back of the skull. Basically... hitting things hurts. Your brain automatically tries to "pull back" just before the moment of impact. So you try to trick the brain by making it think the impact (aka the pain), will occur later than it actually does, so you hit with more force. Possibly something similar can be coming into effect which forward set blades help offset by delivering the impact before the brain expects it, helping you to hit with more force and less of that automatic pullback?
I think two downsides to forward curve as opposed to reverse curved are 1. reverse curved blades are easier to draw from their scabbards in a hurry (like Iaido) and 2. they can glide through a target on horseback while a forward curved would have a harsher impact, and may even cause it to be accidentally dropped.
About the 'feeling' of a better chop from forward facing blade: the unknown quantity probably isn't the forward tilted edge angle at impact, because the more comfortable wrist angle will subtract and replace it, making the impact more like 90 degrees. I think it's other factors. Vibration and wobble after impact have an enormous effect on depth of cut. A strike with the middle of a crescent style sickle has great chopping power for example. The middle has more chopping power than the tip where the impact angle is greater that 90 degrees, and a much better chop than a similar weight straight or regular curved blade has. Upon impact, blades wobble and twist and lose a lot of energy. Impact to the middle of a forward curved blade is more stable. Unfortunately the issue is also confused because most forward facing fighting blades are heavy near the tip, all end weighted blades chop better than even balanced blades. An apples to apples test would be perhaps be a Kukri vs a machete, or a narrow scimitar vs a Ethiopian Shotel.
This is damn interesting! I have often wondered about this exact thing. I hope you dive deeper into this topic and can get some tests set up! Looking forward to it.
I'd definitely love to see testing on this. I wonder how you'd set it up. You would want multiple blades (or other implements) that are as close as possible to identical, except for the curvature of the blade. Same weight, same edge, same grip, same balance.
Forward weighted blades are easy to align BEFORE swinging (Gravity). Backward swept blades are easy to align WHILE swinging (Aerodynamic drag). Likewise, the center of gravity of the former is typically further from handle; the mass helps prevent changes to edge alignment. The latter lacks mass so that aerodynamic drag helps align the blade.
The wrist seems a valid reason. I've also heard it said that having a forward projecting blade makes it so that you are favoring mie the back and shoulder muscles when hitting rather than mostly the wrist and elbow so that your blows have more power
I have an old bowie knife. The tang is parallel with the leading edge, not the spine. So when I am holding it with the false edge foward, it is slightly angled foward of the handle. I'm excited to restore it, and do test cuts with the false edge.
No, it is not about the angle of rotation, but about the angle of the edge. The backward curved slices because the force is angled with the blade. the strait is still slicing a little because center of rotation is moving around to make the swing. The front angled blade can make the angle of cut perpendicular to the edge and therefore doesn't slide/slice and all force is goin into the cut. The blade you have can both slice with the tip and cut in the middle. But you can change how you draw the swing and cut with the tip by trusting your swing, and you can slice with the middle by dragging your swing.
8:49 It is true Matt, the physics of our skeleton and having the blade in front of the lever as you put it, mean that you are continuing to push forward and into and remain in contact longer with more of your skeleton and muscles aligned into the direction of the cut. This part of wrist angle and force direction is a lot like why a paraplegic runner with blades is faster. The entire reason a sword is dangerous is because of the long lever and concentration of force on the edge, a forward curved blade is just mathematically maximizing the amount of energy your skeleton can transfer. Same reason pushing a couch moves it more than kicking it. And the angles with the blade and before the wrist are the same as why bent knees can land quietly and softly but more rigid knees are louder. Because physics is all about the equal and opposite reaction, like using a long, wedged lever to get a force advantage over another warrior. Look at an eagles talons or a vipers fangs, all working under the same principle of maximum force into a point. Like opposite shock absorbers or landing gear, same angles at play here but it's clearer mechanically. The plane would break if it simply landed on sticks so that shock absorber increases the time and spreads out the force absorbed. ...but the aircraft weighs the same to the ground see? More cut per amount of meat that moved it. Math & physics, eventually the best blades become claws and fang shaped. Weapon history and animals evolved the same solutions because physics dictates it. It's also why airplane wings, bird feathers, turbopump rocket engines, jet engines, submarine screws, shape of ships, shape of a feather, shape of a whale... And we literally did get to all that science from exactly what you are doing now, logically thinking with a blade in your hand. Took a few hundred years but we don't call them turbine blades or propeller blades for now reason. It's blowing my mind now that you've started that path over from scratch and already are halfway there to some of the logical math of flight itself. What you've done with an axe is turn a small flat contact area into a more optimal force transfer structure, all by alignment of your body to better take advantage of the force multiplication physics gives you. Cheers mate.
Notice the distance from the hand to the axehead edge is bigger than the shaft. Therefore, in a forward projecting blade, the hitting force is comparable to that of a longest staight blade.
Honestly, even when I was just learning what a sword WAS, as a tiny little kid, I wondered why swords were curved backwards instead of forwards: a forward-curved blade seemed like the most natural thing in the world, if you wanted to cut harder.
I use a Kershaw 18-inch brush knife, no longer made, but resembles their "Camp 10". It has a forward curved blade. In comparison to my Collins machete with a 24-inch blade, it is much more efficient, despite the shorter blade. Other than blade mass, the one thing that seems to make a difference is how much more comfortable it is to cut with. You use your wrist and arm less to deliver the edge to the piece you are cutting. It is less tiring to use.
The Dacian Falx is one of the few weapons that caused the Romans to change their equipment in reaction (ridges on helmets to reinforce them, if memory serves).
Having chopped enough wood with the Khukhri, I'd say you are correct in your assessment. It is usually used as a machete over here in my state atleast & everyone keeps one for general purposes ranging from gardening to animal slaughter.
I think the edge alignment effect might enhance the wrist aspect: I tend to find that it takes a firm grip to keep my khukri aligned, so I naturally grip it tighter. This might have been a benefit for less trained users, who would otherwise not need to keep a firm grip, and thus would loose the benefits of such, if they hadn’t needed to grip it tighter.
Definitely is wrist alignment for me (much older woman, not the strongest wrists). It's why for chopping heavier things in the kitchen (meat, nuts) is easier with even a "light" cleaver than a heavy chef's knife. (Chopping small hard things with a knife is done by "rocking" the chef's knife over the herbs, celery, whatever with a hand on the back to weight it and a hand on the handle...and I just realized, looking againk that the cutting edge of a chef's knife and *some* cleavers has a slight backward curve...also those "rocker" blades. Hmmm. Never thought about things like "edge geometry" and curve direction for a kitchen blade before. THANK YOU. Anyway, I've only ever fenced with a straight blade, so clearly (age nowithstanding) maybe it's time to get a curved blade and try it.
I think mass is the larger factor. Most (not all, but most) weapons that have that edge forward design, also have more mass further away from the hand so they strike "with more authority". Much like a sword that is balanced 8 inches from the hilt as opposed to one balanced at 4 inches; the closer to the hilt the balance point is, the quicker and more nimble the weapon is, but with a reduced chopping/cutting ability.
This is a great area for discussion, and your video has just given me a crazy line of thinking to explore! Let me see if I can capture something on camera really quickly...
The reason I'd think of is that the forward angle forces you to apply pressure while you draw the cut. With backwards curved blades, it would be very easy to only cause a shallow cut when you move the wrong way...
When an axe bounces out of the cut, it jumps out and back toward the user. This shows that some of the forces are traveling in a vetcor back towards the hands of the user. With the cutting surface in front of the hands, more of that force is transfered into the cut, if the cutting edge is in line with the hands, more of this force is watsed with the cutting edge being thrown backwards.
I think that the forward curve chops better because the weight or center of mass on the blade is forward of the lever. This would impart the energy of the swing faster or earlier in the swing than a straight or rear curved blade. Also the sweet spot for chopping is more concentrated than the others.
For testing, ideally you’d find someone willing to make three blades that are as similar as possible except for being forwards curved, backwards curved, and straight.
the Yataghan blade is a really well thought of design since it is forward curving but is still a compromised cut and thrust design and it can also go in and out of a simple straightforward sheath easily
The reason axes has the edge in front of the handle has nothing to do with cutting. The handle is simply less likely to break this way. It is the same with hammers, although hammers don't cut. The shock of the hit/cut has to travel along the head before it reaches the handle, which serves to dampen it. I suspect the same is somewhat true for forward-curved sword blades. For backward-curved blades, I buy into the theory that it helps with getting the blade out, especially for riders. All the other effects, I suspect they are small to negligible. Many people throughout history perhaps believed that curved swords cut better, but I've yet to see a test of this hypothesis.
Many thanks for this video! That’s a very interesting and, I am sure, controversial, topic. I am not really convinced about the angle of attack with various blade designs. I see it this way: The density of air is way lower than the density of the target. This makes the hands (and thus the handle) travel on, drawing the blade through the target regardless of its shape. The chopping makes contact and bites into the material, the slicing finishes the action. Draw cuts thus automatically occur. I really have a hard time considering the postulated, somehow automatic, push cut by Khukris, but I have to try this once. Sounds interesting. According to these ideas, the cut can be done with extended sword with good structure to transfer the energy, still allowing for follow-through. According to my experience, cutting with extended blade is usually preferable in a tactical fighting context but also to enhance the velocity of the cutting section of the blade. I really wonder, what your thoughts are in this regard.
I wouldn't be surprised if there was a psychological component at play too... it's a lot easier to hold the mindset of "punch three inches inside the target" if the thing you're impacting with is three inches ahead of the point you can most intuitively feel the position of. It's not that it's impossible or hard to do otherwise but, like the edge alignment advantages, it just makes "doing the right thing" feel like the natural way to do it. Cycling on a gentle downhill slope doesn't make you a better cyclist, but it still makes you faster.
I thought about this and like how an axe has more chopping power because the force is being applied through a smaller area. The forward curve in say a kukri would have a similar effect to an axe. And also thanks for the info
Another aspect of forward curved blades is tip angle. Some forward curving blades cut in the tip. The Dacian Falx , the middle eastern Jambiya, or even the fairly modern Russian empire Kindjal (when held with the blade forward) These types of forward curved blades have a rip and tearing effect. The Jambiya in particular cuts quite like a giant cat or bears claw.
- I agree, any curvature makes chop cutting easier because the user doesn't have to draw the tool and can focus on the impact - forward curvature for wood chopping is useful mainly because you can aim at a point on a flat surface - in combat, forward curvature makes the weapon more resourceful because you can get around a shield better - in combat, backward curvature makes the weapon more nimble in the defensive as it is less likely to get tangled Do you think a blade which is offset forwards but curves backwards (e.g. falchion, khopesh, even a machete) deserves its own category?
they are better because the blade is always ahead of your hand. we naturally know where our hands are and when hitting things with tools/weapons we instinctively know roughly when to stop the swing. and if the blade is ahead of that point where we stop the swing it bypasses our instinct to look after our hands and not to over exert them. its basically a way of having a stronger chopping action because we don’t realize how far forward the blade is…
I think pressure also plays a factor. Axe whole stick and axe weight is in it. Similar to forward curve blade you have pressure of the rest of the sword behind it.
The leading edge is ahead of the center of gravity. When you swing you aim to hit with the centre of gravity. Thus it hits before the gravity point. Like punching through, instead of punching to tap/slap.
9:05 when you said edge angel and corrected yourself I thought that it was also correct because the convex grind has a lot to do with why the axe penetrates. An ax with a thin bevel like a knife wouldn’t probably. but I think it depends greatly as well on how much weight is in the end of your blade.
Related to the blade being in front of the axis of motion, I wonder if psychologically that has an effect on the user improving their follow-through. The blade hits sooner than would be subconsciously expected based on the position of their arms, so they keep pushing more at the moment of impact. At least for amateurs. Like, when punching a wood board, part of what stops people is they punch for the board but you're supposed to be trying to punch behind the board. So a trick could be to make the board closer than it looks to improve follow-through. Forward-curved blades could have a similar effect.
I am not a physicist but I would think that, to maximize impact energy, you want the weapon's center of mass as close as possible to your target's point of impact. A forward curved blade, as an axe, seems to help in this respect. An axe is perfect to maximize the impact energy. A forward curved blade will not be as good but, as a sword, has other advantages/uses. It should make the curved blade even more effective, from this point of view, if the blade was made slightly wider and thicker (i.e. heavier) towards the area that is supposed to hit the target.
Working with the Greeek kopis, I think the forward curve, as well as the swelling of the blade in the xiphos, aid in draw cuts. The rearward curve of tulwars, etc. make draw cutting easier. But is "ease" the only way to benefit? The forward curve makes it "harder", but it does so because it forces the blade to bite deeper and remain in contact longer as the blade is drawn back. This results in deeper slices. I wonder if the driving force between the ancient penchant for forward curving blades and the later for rearward was better steel, requiring less pressure to cut with a more consistently sharp edge and a longer stroke length or radius of cutting. Perhaps a forward curve allows you to get the most out of a draw cut with a shorter blade.
Matt, what are your thoughts on the Nepalese Kora sword? I own two antique Kora swords I found in the basement of a local high-end antique and art store…the owners of the establishment felt them too “ugly” for display, and sold them to me for $85.00 US Dollars, and $125.00, respectively…ironically, the piece that sold turned out to be a form of Pattern wielded steel known as “quam”, or gravel was the piece that sold for $85.00…I later returned and purchased the remaining antique swords in the barrel…one is a “Firangi” Talwar, with a blade that was made in either France or England, I was told, and the other is a Shamshir with a Talwar hilt; the knuckle bow has been removed at some point in the weapons history… I’m a huge Star Wars fan-(I’m 50)-and was overjoyed to see a shortened version of the Kora being carried by the Gammorian Guards hired by Boba Fett…I readily admit, Mr. Easton, that I was rather hoping to see what kind of Kora sword you might have in your collection…I must also admit to some envy on my part…you seem to be living my dream life, sir! Best wishes from a fan from across the pond…as a Bowie enthusiast, you might like to know that I have the extreme good fortune to live in a state-(Vermont, located in the NorthEastern portion of the United States)-where it is perfectly legal to wear swords and large knives. HEMA isn’t a well known thing in my part of the world, and as I’m originally from the state of South Carolina, I wear a D Guard Bowie from Windlass as part of my daily load out. I’m truly a lucky man. Stay sharp, Mr Easton!
I wonder if there might be a psychological aspect to it. When thinking of a weapon as straight line extension of the arm, you strike such that the end of that extension hits the target with the most force. If at the end of the extension there's a downward angle, 90 degrees for an axe, the end will be more thoroughly embedded in the target because the swing hasn't finished after the target has been struck.
You could probably train with a straight blade to aim slightly beyond/behind the target and still get the strong-wrist effect but it's just natural to do so with a forward curve or edge.
Be careful of ascribing the chopping motion to the wrist solely. What we're dealing with are potentially four arcs of motion from trunk, shoulder, elbow and wrist. So we're generating radial force and the most force will be put into the target when the blade is at 90degrees to the surface. I suspect the forwards positioned blade makes it easier to contact the surface perpendicularly while taking into account the complex arc and relative positions of strength of the pivot points along the way. Curvature of the blade is in part a way of reducing surface area and thus increasing pressure at the contact point.... improving penetration (not necessarily shear force which is different)
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There are some complicated dynamics at work that can be difficult to untangle due to the stroke having almost as much influence on the cut in practice. I've done a lot of work studying the balance of axes, scythes, and other asymmetrical tools, including machetes, swords, cleavers, and so on. Presentation of the cutting line, mass distribution, and the spatial positioning of the edge relative to the range of motion of the stroke, as well as other factors, will compound to contribute to cutting performance. Isolating the edge forwards of the hand alone without an overall increase in blade mass, as in a khopesh, mostly influences the point at which the edge meets the target, allowing for greater impulse and follow-through at the expense of reducing the distance over which you are able to accelerate the weapon before impact.
Would love to chat more about it but it's much more than I can cover in a RUclips comment.
There is a discord now!
Good comment though. Well stated. Favor the khukuri for chopping, but just bought a khopesh to compare that exact thing, mass at point of impact versus swing efficiency. Interesting topic, to be sure...
Do you work for Baryonyx Knive and Tool?
Where can I find more info?
@@FerociousSniper I've given lectures on the subject but don't have any blog posts on it currently, I'm afraid.
Apologies for the re-post. I accidentally sent one from my gaming channel 😅
I think also regards to your chopping theorem, its important that youre contacting earlier in the arc of your powerstroke and can exert more force over a longer time on what you're cutting
It's kind of like the "don't punch his face, punch behind his head" from boxing/martial arts
I absolutely think you're right about wrist angle being a part of it. And it'd also be interesting for you to revisit the Indian hilts on backwards curved blades that also "lock in" one's wrist and see if you feel (literally 😏) that the same benefit applies.
I chop wood with a parang and the blade being slightly forward of my wrist does make a lot of sense, keeping a stronger wrist makes it feel like I don't need to put as much effort in
When I used to help my brother-in-law chop wood, I got to use an axe that had a larger head than I was used to, and it did feel more 'right'. I put it down to just feeling a little safer with slightly more distance between my hand and the impact, but it was just a feeling.
Agree,
Although there are backward curving parang designs too, the forward curving ones feels much better in the hand. It gives that satisfying bite feel to it when it hits the target.
Forward curved swords like a Falcata, Yataghan, Kukri and even Falx amongst other styles definitely cut way better IMO.
Single edged sword's also have the mass of the spine directly behind it. The forward balance of some those swords helps.
I love them, and think Sabres to Katanas are over rated. Let us bother Matt or Skall to commission a two handed yataghan.
Love them. What is the proper name for that first sword he brought up? Yatagahn?
Oh and draw cuts can be vicious as they kind of catch, and digs deeper as it drags.
I think your idea of wrist angle is valid. I have done extensive land clearing with both a straight machete and a kukrhi. Even with the machete being lighter and longer, I don't feel as tired when using the kukrhi. It also feels more powerful. Look forward to whatever testing you can do.
Amen to that. Used a khukuri to clear a firebreak lane, could not believe how easy it was compared to other tools I have used.
Less fatigueing grip, letting it just rock in the hand, movwing through even two inch branches and vines in a couple chops. Almost as fast literally as the guts with chainsaws next to me. Totally convinced me of the difference in blade geometry for specific applications.
Feel free to correct me, but I believe having the forward curved blade puts the center of gravity forward as well. Mixed with wrist position, this would allow for more/easier penetration with chops.
Yep, I agree
As a blacksmith, I want my wrist to be pretty square when I strike like how you described with the forward curved blades and axes. Also as a blacksmith, forward curved blades Are harder to make, and sharpen lol.
Hi, Mat.
I like forward curving blades.
Here's a couple of ideas on why it's better;
1 ▪Forward Power Projection
Ie like punches delivered in many traditional martial arts forms, you don't actually aim to hit the object you're targeting, but actually a bit of a distant behind it. Hence, a punch to the face isn't aimed at the face, but a distant beyond the face. So you're in essence punching through. Hence, the power projection is greater at the point of impact. A forward curving blade brings about the same effect as the the "feel" of the aim is "at the wrist". But the the impact of the forward curvature arrives first. Hence the wielder of the blade has the tendency to continue the drive forward until he feels the wrist has actually arrived at the blade. This driving through projects alot more power and hence, cutting action at the point of impact. Just like a traditional martial arts punch or strike.
2. Modified Drawing Cut
Asian swordfighting techniques used alot of the drawing cut technique. For forward curving blade, the initial cut, which hacks through the target, is then followed by a drawing action. Ie the drawing of the blade to initiate its released from the body.
Since the blade is forward curved, the wielder needs to only pull the blade in a straight back lateral draw as opposed to a more curved draw for a backward curving blade. The forward curving blade acts like a hook, to sort of hold the body and keep it in place. Even if the body were to fall backward, the fall of the body would still allow for the cut to take place. A rear curving blade in comparison will have the body falling away from the blade. This hooking effect, creates a longer contact to enhance the slicing action.
I've tried this out using ripe papayas on my antique South East Asian, forward angled Moro Kerises and Sumatran Badeks. Welcomed comments from fellow enthusiasts here as I'm keen to expand my knowledge too.
Might be a fun and enlightening collab with Tod (along the lines of the "Weird historicals" series) for him to try making a reasonable forward-curving/forward-projecting blade that *isn't* a good cutter. Seeing why one doesn't work could help to pin down why most of them do work.
I've loved forward curving blades because of their aggressive aesthetic, their traditionally believed superiority as choppers, and because depending on the shape of the tip they can even give a stronger wrist alignment when thrusting, akin to a pistol grip. So yeah, I'd love to see more info quantifying the performance of such blades in chopping.
However, my love for forward curving blades has forced me to come to terms with the seemingly far greater popularity of backward curves on curved blades. Which begs the question of why they're so much more popular. I suspect that a big part of it is that given the ubiquity of shields through most of history, the utility of a backward curved blade in delivering underhand and backhand pokes under, over, or around a shield was extremely useful. I feel like the popularity of cat's claw tips is additional evidence of this. Add to that the ability of a backward curving blade to give very long cuts, potentially with much of the length of the blade and that's probably the reason that form factor is so popular.
As a fellow fan of forward curving blades, I have also thought about this. I tend to think it’s much more to do with slicing length versus chopping power. I actually feel like a forward curved blade might be better suited for poking around shields than a backwards curved blade.
@@spleenjacobson203 As for some examples for weapons that are useful vs shields are the egyptian khopesh or the scythian/thracian/persian sagaris. In later periods where the sword becomes a 100% side weapon, these traits are found in polearm weapons like the various chinese Ji or Ge variations & the scythia/Crimean great axe (medieval two-handed weapon, similar to danish longaxe but usually longer, uses a Π blade to reduce weight and be nimble, in general big axes were favored in Crimea region). Shield walls in the dark ages were very common and the danish longaxe & the scythian great axe (also used by the sarmatians/alans) was used for that reason by the Varangian mercenaries (Norse, Rus, Saxon or Anglosaxon origin) of the Eastern Roman Empire against tired foes to completely rout them. As for the Ji/Ge it become just like the Halberd, especially as armor use was reduced. Egyptians primarily used maxes and spears if they didnt use missile weapons.
Thank you!!! I've never see sword videos that mention DRAWING the blade. Never thought of hitting at an angle would effectively narrow the edge - THANK YOU!!!
Sooo refreshing! It helps me in pulling myself together and finding a solid ground underneath my feet. Thank you. Greetings from Prague, Czech Republic.
From physics point of view the length of the effective lever is increased by placing the striking part in front of the handle which in turn increases the torque and thus speed and power. However the effect seems quite minor unless some very strong forward curve. Your axe for example would only get around 4% increase in toque (applied pythagoras' law and thought of the axe head and shaft as the legs of a right triangle and the effective lever as the hypotenuse and measured lengths by eye). The Problem with this idea is that increasing the length of the weapon would do the same thing and also increase reach.
Last point very good. Extends well into a general point about biomechanics. You want to hit your target at the point where 2 conditions are jointly maximised.
1. Acceleration of cutting edge. This maximises the force of the cut, past this point the blade slows.
2. Stiffness of body. By this I mean that you lose less energy on impact, the more your body gives, the less force is transferred to the target.
So its not just having your wrist in a strong position, it is your entire body.
To take your axe analogy, image in the head a few inches behind the handle and you are aiming to hit a targey a few feet in front of you. Generally speaking your swing is already finished upon the hit, there are fewer muscles in an optimal position.
Finally, in prsctical terms, if you want to biomechancially put yourself in a better position to cut, you have to compromise by shifting your centre of balance more - which leaves openings. So you need to consider being able to cut well from more angles, without swinging wildly is just as important as the cut itself.
Source: pure speculation.
I have realized that I have had quite a lot of problems with wrist extensions while using straight weapons (while training kali). This video was very helpful for how I can work this into future weapons! I appreciate it! ✨
The relationship between the angle of attack and edge geometry, and the strength vs wrist position concept are news to me. It's fun to learn something new.
I personaly think it might be a biomechinacal reason. Your wrist isn't that strong of a point in your body. In many positions it's just weak and will easly be overpowerd. Sow having your wrist bent into a cut will dempen the blow. There is how ever a position in which you can lock your wrist to such a degree that it's a rather strong point that's very unlikely to move. That's when you make a fist. Things that have the hitting portion infront are more likely to hit when your still making a fist aka the blow isn't dempining much and your able to maintain much more power from your strike. Sow I think it has to do with how the weapon functions in relation to the body and not with anything related to the weapon it's self.
A bunch of people (including Matt in the video) have already said the thing about wrist position but I just thought I'd add a few additional thoughts on that same thing.
1. Instead of phrasing it as wrist position you can also think of it as the angle my arm must be it (for the same wrist position), this can be a useful way to veiw it too (I think) given how powerful the muscles of the wrist vs the arm are.
2. I believe that elbow muscles are significantly more powerful when the elbow is in a bent position. There are atleast a few potential biological reasons for this like where exactly the attachment points are on the forearm bones, how the muscles' deformation impacts the positioning of and forces acting upon the individual strands and acting proteins in the muscle fibres, the impact of them having to stretch of their complementary muscles (especially if all your muscles are a bit tense cus you might die).
3. The forwards curve may sometimes be essentially necessary to reach a place at all. If I imagine trying to cut upwards into the inside of someone's thigh or groin or up into their armpit the angle of my arm is such that, short of kneeling down, a straight blade just isn't really going to connect. At best it'll hit them mostly front on, which may be useless if I was targetting that point specifically to exploit the common lack of armour there.
I also think that it could be interesting to explore the positioning of different thrusts with different shaped blades because a forwards curve facilitates thrusts more directly in line with your forearm, potentially making them more powerful thrusts but also restricting the arm position they can be made from. While a straight blade allows thrusts to be performed up from a low arm position, and lets your wrist-sword joint form a significant angle allowing to thrusts around objects.
This may be difficult to explain, but watching the motion of the blades I can see it: the ace is easiest to see: the point of the forward curve (on the axe where the head protrudes forward from the shaft) becomes a second fulcrum. At the point in the swing where impact would occur, the edge begins to also swing in an arc simultaneously down AND toward the person swinging. All fulcrums in moving in this swing have longer levers behind them, so they are increasing the force in the smaller arc swinging back toward the cutter as well. It’s essentially a “compound blade” at that point.
If you ask Lindybeige, he'll probably tell you it's because they can go round corners and the object being cut isn't ready for it.
I think you are on the right track with th extended wrist theory. Whenever hitting a target, it is important to be in a strng position to be able to put one's entire body's strength to the highest possible degree behind that position. It allows for powerful hits, sturdy blocks and strong defense against disarm attempts, or against pushes into the weapon after it being blocked. Simply put, with the wrist not fully extended, the wrist is way more braced against vibrations coming back to the hand from the hit. That really does sound like the most likely explanation for why these blades feel like they cut better. For a very similar reason, very rattly handle feels feeble and very unpleasant to use and cut with.
Your comment, at the 10:00 mark, about wrist angle, is I think the answer. A comparison of a modern double-bitted axe (straight grip coaxial with the straight handle, used in logging) and a modern single-bitted axe with a curved grip area supports this. The single-bitted axe is more comfortable to use. A double-bitted axe with a single-bitted axe handle would be pointless. Splitting mauls usually have straight handles, but they rely much more on the weight of the head than axes do. Note that the single-bitted axe geometry falls in the middle of the range of the weapons you displayed (kukri, sosun pattah), although the sosun pattah you display seems to be of a much less curved variety. Most of the ones I've seen have a continuous curve along the back edge from guard to tip.
An addition to the point about the wrist angle.
If the point of impact is ahead of the lever and your wrist is straight, that means your body is still accelerating the lever at the moment of impact compared to a straight blade where you will physically start to deaccelerate the lever to either avoid over extension, over balancing or to change the direction of the blade into recovery, and just like a compression spring has the least amount of power at full extension, the same is true for our joints and muscles, their effect is the most powerful half way between full extension and full contraction.
I always figured one reason why curved blades (both backwards and forwards) tend to cut better is because the energy from the impact is focused on a smaller surface area on the target than it typically would be with a straight blade. It becomes a little bit more like a point as opposed to a line, or rather a shorter line as opposed to a longer line.
*Look at airplane wings and drag.*
*As I said in Shad's video, I always thought it had to do with aerodynamics.*
For those who don't know / forgot, drag is the resisting force pushing against an object in motion in fluid mechanics. The shape of an object collects a certain amount of drag when moving through the air, and we know curves cut through the air better and more efficiently than straight angles and boxes. It's one reason why economical cars have so many curves and box trucks can be such gas guzzlers.
The nature in which airplanes (aeroplanes) fly changes dramatically when you fit it with straight wings versus swept and curved wings, even when nothing else about the aircraft is altered. Planes with fat, wide, long, rectangular wings are more often designed for long loiter time (hanging out over a target in the air), generally increasing lift and resisting tendencies to adjustments from the environment. However, this shape actually slows down the airplane, or at least limits it's speed capacity, with greater drag.
Wings that are swept-wing (curved or angled) can cut through the air faster while using less power. The shape changes the aerodynamic center, increase Mach-number capability by delaying to a higher speed the effects of compressibility (abrupt changes in the density of the airflow), e.g. combat aircraft, airliners and business jets, and reduces bending moments under high g-loadings. Flying wing design aircraft have _the_ lowest drag problems, but have the most trouble maintaining balance and control.
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It stands to reason that a straight blade incurs more drag than a curved sword does. You might be able to test this by putting swords in wind tunnels.
I have a repro two banded muzzle loading musket made in England years ago by Parker Hale. I got an original Enfield bayonet for it. It has that Yadzighan (? Spelling) blade. This narrative gives it an additional purpose. Thank you.
Don't threaten me with an hour(s) long video of epic backyard cutting with dozens of swords! Because I will make popcorn and watch that. Maybe twice just to teach you a lesson.
Great point, blade forward much better feels much more comfortable in the hand and you seem to get more torque.
I think it comes down to leverage and force concentration. The longer the distance of the lever (your arm + the blade) for your strike, the greater the force at the end, and the sturdier the lever (being able to keep the wrist locked while also reaching outwards with a forward-curved blade) translates to greater follow-through on impact in an ideal scenario. Then you have the nature of the edge like you noted 'pushing' forward in the cut, great for vulnerable targets like arms would easily be fully within this cutting area and get the fullest effect from the 'push' of the cutting motion when it impacts, creating greater cleaving effect. Finally, the edge contacts a smaller amount of the target at first and dramatically widens its area of contact to spend that momentum rapidly.
I think the wrist angle point is a good one. I think that's why hammers and mallets (tools and weapons) are designed that way as well.
Mr. Easton, you should add a part to explain this with a farm or garden sickle or billhook, because more people have sickles or billhook at home. They have a long history and are common throughout the world.
Of course you also know that such agricultural tools were used as weapons.
However, Like sickles and axes, the sheaths of forward curved blades are more difficult to make.
If you look at civilian utility axes, the end of the handle usually curves forward to enhance the degree to which the blade is "forward". I think it's simply a matter of getting a better extension of your arm, while keeping your wrist angle natural. This has a couple important effects:
1) This practically eliminates wrist effort and fatigue, as the ax simply "holds itself" outward due to centrifugal force. You aren't exerting any wrist torque controlling the handle angle. This is important because your wrist muscles are weak, with little leverage, compared to your other arm/back muscles.
2) It provides the best distance from your elbow to the ax head. The handle and arm are practically straight. Besides the obvious safety aspect of keeping that further away from you, it simply provides a lot more impact velocity for a given amount of arm swing angular velocity. The bottom line is that more kinetic energy is in the ax head and less kinetic energy is "wasted" in swinging your own arm around.
There's also something of a trebuchet-like "whip" effect, which has the effect of transferring kinetic energy from the swing arm to the ax head. The rotation of the ax itself "whips" the ax head forward while simultaneously slowing your arm. This only works if your wrist is somewhat "limp", but if your wrist is bent almost as far as it can go, then it will be resisting the ax handle's rotation rather than flowing with it.
I think both the momentum of the thing moving forwards is a factor, and I would also mention (many other people are bringing up biomechanics points) that it would change how you need to rotate and which muscles you need to exert. With a back-curved blade with longer strokes I feel the need to control for a long time through the strike and use up my arm muscles a lot, with more forwards-curves needing a lot more exertion early on from the fingers, especially the pinky, but then the momentum essentially takes over. So it makes sense for short weapons, especially ones that wouldnt do much damage without more chopping in, not having much bladeage (a word?) to shear with or acceleration at the tip. I would also add that back-curves shorten your reach (at natural arm extension the centre of percussion still hasn't reached the target, so the cut has to be pulled for longer, and with the arm muscles), so curving them forwards (getting the angle of attack benefit from a curved blade) and then recurving back brings the point back on line and restores your reach, at the cost of control during the actual stroke (if it's very short that's minor). I do think that non-recurved forwards-curves, eg. the Japanese forwards-curved Katana, dont make much sense, the risk of getting an enemy stuck in the middle of it would suck. Even Kukris recurve slightly.
The Katana takes this to the extreme in that the whole thing is a banana, ie the handle continues the curve of the blade backwards. To the extent that's deliberate and they actually thought about it, it'll have the effect, assuming I'm right, of maximising reliance on the skill of the swordsman and relying entirely on the muscles (obviously it still has *some* momentum) rather than a "fire-and-forget" power stroke.
The kopis/falcatta looks cool as heck, and that is why people used forward-curving swords.
I might be completely wrong about this analogy, but when you thrust with a longer spear, a smaller movement of your arm(s) means a more impactful thrust because there's length moving at once behind the point. I feel like the same might be true of forward-curving blades and axes, where even that slight protrusion means that, for a brief moment, all the energy put into the swing of the entire weapon rests on whatever it hits before your arm goes past the target. Just in instinctual thing.
I think the wrist position is a longer conversation, because it also means the rest of your arm is in a different position, and also it means the blade will impact during a different point in it's pendulum motion. I want to imagine an analogy of the bucket of water being swung around the body to hold the water in the bucket. I also want to imagine an analogy of stability between balancing a stick above your hand, vs. allowing it to hang. (prop plane vs. fighter jet). When propellers are designed for steady speed, they are long and straight, when propellers are designed for heavy load (boat props) they curve back hard and are short. When propellers are designed for rapid acceleration and deceleration, they are also steeply curved and shorter. Hydraulic joints are another place where an offset can result in a leverage advantage or stability advantage.
I agreed on the way it works like a woodaxes, which is also for meat knife, to prevent blades stuck on target, wood or bone just by rotate it upward from wrist, the blade are easy to release from stuck positions.
I don't know mathematically why, but consider the earliest chopping tools the hand axe. It is held with the blade preceding the arm out of the fist. It focuses the energy of the basic primate overarm blow and doesn't break its efficient body mechanics. Chopping (not slicing) with one that trails the hand will put extra stress on the grip while delivering less impact since it comes past the point of optimal energy transfer for the motion.
I picked up a Bushmanster (United Cutlery) knife described as a Kukri with a 12" blade. Howiever the back of the blade is fairly straight since it has a sawback. I wnated this as a bush knife that could cut materials more sturdy than would be vulnerable to a machete. Here in New England most of our large bushes have woody stems. The blade is made of aus-6 stainless steel HRC 55-58
All about the wrist. Glad you mentioned it
As many will know, in all martial arts, a strike is more effective when it is focussed behind the target, as the blow is still getting forward momentum after it hits, so rather than the power being at it's peak when the wrist is fully extended, the push continues and allows the blade to be withdrawn faster for another blow before the wrist is at its weakest point.
I think the wrist angle is just one of several factors that all combine to mean more mass (both that of the tool and of the wielder) and thus more energy brought to bear behind the edge more directly at the moment of contact. Specific technique is a huge variable, but the mass with a backward curved blade is more inclined to lead the point of impact so that the energy delivery is more drawn out with the follow-through. A straight blade then has poorer energy transfer at the point of contact than the forward swept blade and than the backward swept blade in the follow through, but can more readily mimic (to a degree) the effect of either through adjustments to technique.
Mate, I think you nailed it! I would love to see you and Todd investigated further.
Weird little thing that I dont know if people really consider...
When I was training martial arts, part of what I was taught when say for example throwing a strike at someone's face... Don't try to punch their face, try to punch through it, envision punching the back of the skull.
Basically... hitting things hurts. Your brain automatically tries to "pull back" just before the moment of impact. So you try to trick the brain by making it think the impact (aka the pain), will occur later than it actually does, so you hit with more force.
Possibly something similar can be coming into effect which forward set blades help offset by delivering the impact before the brain expects it, helping you to hit with more force and less of that automatic pullback?
My guess was always just a smaller area of potential contact
Forward curved actually means more area of contact, at least on relatively rounded objects.
I think two downsides to forward curve as opposed to reverse curved are 1. reverse curved blades are easier to draw from their scabbards in a hurry (like Iaido) and 2. they can glide through a target on horseback while a forward curved would have a harsher impact, and may even cause it to be accidentally dropped.
About the 'feeling' of a better chop from forward facing blade: the unknown quantity probably isn't the forward tilted edge angle at impact, because the more comfortable wrist angle will subtract and replace it, making the impact more like 90 degrees. I think it's other factors.
Vibration and wobble after impact have an enormous effect on depth of cut. A strike with the middle of a crescent style sickle has great chopping power for example. The middle has more chopping power than the tip where the impact angle is greater that 90 degrees, and a much better chop than a similar weight straight or regular curved blade has.
Upon impact, blades wobble and twist and lose a lot of energy. Impact to the middle of a forward curved blade is more stable.
Unfortunately the issue is also confused because most forward facing fighting blades are heavy near the tip, all end weighted blades chop better than even balanced blades. An apples to apples test would be perhaps be a Kukri vs a machete, or a narrow scimitar vs a Ethiopian Shotel.
This is damn interesting! I have often wondered about this exact thing. I hope you dive deeper into this topic and can get some tests set up! Looking forward to it.
I'd definitely love to see testing on this. I wonder how you'd set it up. You would want multiple blades (or other implements) that are as close as possible to identical, except for the curvature of the blade. Same weight, same edge, same grip, same balance.
Forward weighted blades are easy to align BEFORE swinging (Gravity). Backward swept blades are easy to align WHILE swinging (Aerodynamic drag). Likewise, the center of gravity of the former is typically further from handle; the mass helps prevent changes to edge alignment. The latter lacks mass so that aerodynamic drag helps align the blade.
The wrist seems a valid reason. I've also heard it said that having a forward projecting blade makes it so that you are favoring mie the back and shoulder muscles when hitting rather than mostly the wrist and elbow so that your blows have more power
I have an old bowie knife. The tang is parallel with the leading edge, not the spine. So when I am holding it with the false edge foward, it is slightly angled foward of the handle. I'm excited to restore it, and do test cuts with the false edge.
No, it is not about the angle of rotation, but about the angle of the edge. The backward curved slices because the force is angled with the blade. the strait is still slicing a little because center of rotation is moving around to make the swing. The front angled blade can make the angle of cut perpendicular to the edge and therefore doesn't slide/slice and all force is goin into the cut. The blade you have can both slice with the tip and cut in the middle. But you can change how you draw the swing and cut with the tip by trusting your swing, and you can slice with the middle by dragging your swing.
8:49 It is true Matt, the physics of our skeleton and having the blade in front of the lever as you put it, mean that you are continuing to push forward and into and remain in contact longer with more of your skeleton and muscles aligned into the direction of the cut. This part of wrist angle and force direction is a lot like why a paraplegic runner with blades is faster. The entire reason a sword is dangerous is because of the long lever and concentration of force on the edge, a forward curved blade is just mathematically maximizing the amount of energy your skeleton can transfer.
Same reason pushing a couch moves it more than kicking it. And the angles with the blade and before the wrist are the same as why bent knees can land quietly and softly but more rigid knees are louder. Because physics is all about the equal and opposite reaction, like using a long, wedged lever to get a force advantage over another warrior.
Look at an eagles talons or a vipers fangs, all working under the same principle of maximum force into a point.
Like opposite shock absorbers or landing gear, same angles at play here but it's clearer mechanically. The plane would break if it simply landed on sticks so that shock absorber increases the time and spreads out the force absorbed. ...but the aircraft weighs the same to the ground see?
More cut per amount of meat that moved it. Math & physics, eventually the best blades become claws and fang shaped. Weapon history and animals evolved the same solutions because physics dictates it.
It's also why airplane wings, bird feathers, turbopump rocket engines, jet engines, submarine screws, shape of ships, shape of a feather, shape of a whale...
And we literally did get to all that science from exactly what you are doing now, logically thinking with a blade in your hand. Took a few hundred years but we don't call them turbine blades or propeller blades for now reason.
It's blowing my mind now that you've started that path over from scratch and already are halfway there to some of the logical math of flight itself.
What you've done with an axe is turn a small flat contact area into a more optimal force transfer structure, all by alignment of your body to better take advantage of the force multiplication physics gives you.
Cheers mate.
Notice the distance from the hand to the axehead edge is bigger than the shaft.
Therefore, in a forward projecting blade, the hitting force is comparable to that of a longest staight blade.
Honestly, even when I was just learning what a sword WAS, as a tiny little kid, I wondered why swords were curved backwards instead of forwards: a forward-curved blade seemed like the most natural thing in the world, if you wanted to cut harder.
I use a Kershaw 18-inch brush knife, no longer made, but resembles their "Camp 10". It has a forward curved blade. In comparison to my Collins machete with a 24-inch blade, it is much more efficient, despite the shorter blade. Other than blade mass, the one thing that seems to make a difference is how much more comfortable it is to cut with. You use your wrist and arm less to deliver the edge to the piece you are cutting. It is less tiring to use.
I think that first Indian re-curved blade is my favorite and second would be a Saxon sword always got a soft spot for Saxon swords
Best explanation of this I've heard
The Dacian Falx is one of the few weapons that caused the Romans to change their equipment in reaction (ridges on helmets to reinforce them, if memory serves).
Having chopped enough wood with the Khukhri, I'd say you are correct in your assessment. It is usually used as a machete over here in my state atleast & everyone keeps one for general purposes ranging from gardening to animal slaughter.
"Have you seen those warriors from Hammerfell? They have curved swords! CURVED.... SWORDS!"
I think because of the geometry, and the fact that it's swung rather than thrusted, it slices deeper and deeper as it is swung and dragged.
I think the edge alignment effect might enhance the wrist aspect: I tend to find that it takes a firm grip to keep my khukri aligned, so I naturally grip it tighter. This might have been a benefit for less trained users, who would otherwise not need to keep a firm grip, and thus would loose the benefits of such, if they hadn’t needed to grip it tighter.
Definitely is wrist alignment for me (much older woman, not the strongest wrists). It's why for chopping heavier things in the kitchen (meat, nuts) is easier with even a "light" cleaver than a heavy chef's knife. (Chopping small hard things with a knife is done by "rocking" the chef's knife over the herbs, celery, whatever with a hand on the back to weight it and a hand on the handle...and I just realized, looking againk that the cutting edge of a chef's knife and *some* cleavers has a slight backward curve...also those "rocker" blades. Hmmm. Never thought about things like "edge geometry" and curve direction for a kitchen blade before. THANK YOU. Anyway, I've only ever fenced with a straight blade, so clearly (age nowithstanding) maybe it's time to get a curved blade and try it.
I think mass is the larger factor. Most (not all, but most) weapons that have that edge forward design, also have more mass further away from the hand so they strike "with more authority". Much like a sword that is balanced 8 inches from the hilt as opposed to one balanced at 4 inches; the closer to the hilt the balance point is, the quicker and more nimble the weapon is, but with a reduced chopping/cutting ability.
This is a great area for discussion, and your video has just given me a crazy line of thinking to explore! Let me see if I can capture something on camera really quickly...
The reason I'd think of is that the forward angle forces you to apply pressure while you draw the cut. With backwards curved blades, it would be very easy to only cause a shallow cut when you move the wrong way...
When an axe bounces out of the cut, it jumps out and back toward the user. This shows that some of the forces are traveling in a vetcor back towards the hands of the user.
With the cutting surface in front of the hands, more of that force is transfered into the cut, if the cutting edge is in line with the hands, more of this force is watsed with the cutting edge being thrown backwards.
Much how a pointy tip helps a thrust penetrate, a curve also concentrates force on a smaller point.
I think that the forward curve chops better because the weight or center of mass on the blade is forward of the lever. This would impart the energy of the swing faster or earlier in the swing than a straight or rear curved blade. Also the sweet spot for chopping is more concentrated than the others.
Center of percussion is forward. Makes less nimble but a bit more formidable.
For testing, ideally you’d find someone willing to make three blades that are as similar as possible except for being forwards curved, backwards curved, and straight.
the Yataghan blade is a really well thought of design since it is forward curving but is still a compromised cut and thrust design and it can also go in and out of a simple straightforward sheath easily
also Yatagan looks freaking cool !
one of the coolest looking blade in my opinion
The reason axes has the edge in front of the handle has nothing to do with cutting. The handle is simply less likely to break this way. It is the same with hammers, although hammers don't cut. The shock of the hit/cut has to travel along the head before it reaches the handle, which serves to dampen it. I suspect the same is somewhat true for forward-curved sword blades.
For backward-curved blades, I buy into the theory that it helps with getting the blade out, especially for riders. All the other effects, I suspect they are small to negligible. Many people throughout history perhaps believed that curved swords cut better, but I've yet to see a test of this hypothesis.
I'd speculate that the mechanically advantageous wrist angle is actually the most important part.
Many thanks for this video! That’s a very interesting and, I am sure, controversial, topic. I am not really convinced about the angle of attack with various blade designs. I see it this way: The density of air is way lower than the density of the target. This makes the hands (and thus the handle) travel on, drawing the blade through the target regardless of its shape. The chopping makes contact and bites into the material, the slicing finishes the action. Draw cuts thus automatically occur. I really have a hard time considering the postulated, somehow automatic, push cut by Khukris, but I have to try this once. Sounds interesting. According to these ideas, the cut can be done with extended sword with good structure to transfer the energy, still allowing for follow-through. According to my experience, cutting with extended blade is usually preferable in a tactical fighting context but also to enhance the velocity of the cutting section of the blade.
I really wonder, what your thoughts are in this regard.
I wouldn't be surprised if there was a psychological component at play too... it's a lot easier to hold the mindset of "punch three inches inside the target" if the thing you're impacting with is three inches ahead of the point you can most intuitively feel the position of. It's not that it's impossible or hard to do otherwise but, like the edge alignment advantages, it just makes "doing the right thing" feel like the natural way to do it.
Cycling on a gentle downhill slope doesn't make you a better cyclist, but it still makes you faster.
I thought about this and like how an axe has more chopping power because the force is being applied through a smaller area. The forward curve in say a kukri would have a similar effect to an axe. And also thanks for the info
Another aspect of forward curved blades is tip angle. Some forward curving blades cut in the tip. The Dacian Falx , the middle eastern Jambiya, or even the fairly modern Russian empire Kindjal (when held with the blade forward) These types of forward curved blades have a rip and tearing effect. The Jambiya in particular cuts quite like a giant cat or bears claw.
- I agree, any curvature makes chop cutting easier because the user doesn't have to draw the tool and can focus on the impact
- forward curvature for wood chopping is useful mainly because you can aim at a point on a flat surface
- in combat, forward curvature makes the weapon more resourceful because you can get around a shield better
- in combat, backward curvature makes the weapon more nimble in the defensive as it is less likely to get tangled
Do you think a blade which is offset forwards but curves backwards (e.g. falchion, khopesh, even a machete) deserves its own category?
I think you're right about the wrist angle idea, but also that it applies to the swing itself! When the hand passrs the body you start to lose power.
they are better because the blade is always ahead of your hand. we naturally know where our hands are and when hitting things with tools/weapons we instinctively know roughly when to stop the swing. and if the blade is ahead of that point where we stop the swing it bypasses our instinct to look after our hands and not to over exert them. its basically a way of having a stronger chopping action because we don’t realize how far forward the blade is…
I think pressure also plays a factor. Axe whole stick and axe weight is in it. Similar to forward curve blade you have pressure of the rest of the sword behind it.
You hit it with wrist angle, I think- that's a strong position. And you *feel* the power delivery with those blades.
I always also kinda assumed it's because you can use more of a pulling motion like with a sickle
Thank you!!! I have wondered about this for a long time.
Main factor in my opinion: The length of the blade through which the force is transferred
The leading edge is ahead of the center of gravity. When you swing you aim to hit with the centre of gravity. Thus it hits before the gravity point.
Like punching through, instead of punching to tap/slap.
9:05 when you said edge angel and corrected yourself I thought that it was also correct because the convex grind has a lot to do with why the axe penetrates. An ax with a thin bevel like a knife wouldn’t probably. but I think it depends greatly as well on how much weight is in the end of your blade.
Related to the blade being in front of the axis of motion, I wonder if psychologically that has an effect on the user improving their follow-through. The blade hits sooner than would be subconsciously expected based on the position of their arms, so they keep pushing more at the moment of impact. At least for amateurs.
Like, when punching a wood board, part of what stops people is they punch for the board but you're supposed to be trying to punch behind the board. So a trick could be to make the board closer than it looks to improve follow-through. Forward-curved blades could have a similar effect.
I am not a physicist but I would think that, to maximize impact energy, you want the weapon's center of mass as close as possible to your target's point of impact. A forward curved blade, as an axe, seems to help in this respect. An axe is perfect to maximize the impact energy. A forward curved blade will not be as good but, as a sword, has other advantages/uses. It should make the curved blade even more effective, from this point of view, if the blade was made slightly wider and thicker (i.e. heavier) towards the area that is supposed to hit the target.
Working with the Greeek kopis, I think the forward curve, as well as the swelling of the blade in the xiphos, aid in draw cuts. The rearward curve of tulwars, etc. make draw cutting easier. But is "ease" the only way to benefit? The forward curve makes it "harder", but it does so because it forces the blade to bite deeper and remain in contact longer as the blade is drawn back. This results in deeper slices.
I wonder if the driving force between the ancient penchant for forward curving blades and the later for rearward was better steel, requiring less pressure to cut with a more consistently sharp edge and a longer stroke length or radius of cutting. Perhaps a forward curve allows you to get the most out of a draw cut with a shorter blade.
Matt, what are your thoughts on the Nepalese Kora sword? I own two antique Kora swords I found in the basement of a local high-end antique and art store…the owners of the establishment felt them too “ugly” for display, and sold them to me for $85.00 US Dollars, and $125.00, respectively…ironically, the piece that sold turned out to be a form of Pattern wielded steel known as “quam”, or gravel was the piece that sold for $85.00…I later returned and purchased the remaining antique swords in the barrel…one is a “Firangi” Talwar, with a blade that was made in either France or England, I was told, and the other is a Shamshir with a Talwar hilt; the knuckle bow has been removed at some point in the weapons history…
I’m a huge Star Wars fan-(I’m 50)-and was overjoyed to see a shortened version of the Kora being carried by the Gammorian Guards hired by Boba Fett…I readily admit, Mr. Easton, that I was rather hoping to see what kind of Kora sword you might have in your collection…I must also admit to some envy on my part…you seem to be living my dream life, sir!
Best wishes from a fan from across the pond…as a Bowie enthusiast, you might like to know that I have the extreme good fortune to live in a state-(Vermont, located in the NorthEastern portion of the United States)-where it is perfectly legal to wear swords and large knives. HEMA isn’t a well known thing in my part of the world, and as I’m originally from the state of South Carolina, I wear a D Guard Bowie from Windlass as part of my daily load out. I’m truly a lucky man.
Stay sharp, Mr Easton!
Wowie first! Forward blades ftw.
I wonder if there might be a psychological aspect to it. When thinking of a weapon as straight line extension of the arm, you strike such that the end of that extension hits the target with the most force. If at the end of the extension there's a downward angle, 90 degrees for an axe, the end will be more thoroughly embedded in the target because the swing hasn't finished after the target has been struck.
I believe that design guides inside and cut.
You could probably train with a straight blade to aim slightly beyond/behind the target and still get the strong-wrist effect but it's just natural to do so with a forward curve or edge.
Be careful of ascribing the chopping motion to the wrist solely. What we're dealing with are potentially four arcs of motion from trunk, shoulder, elbow and wrist. So we're generating radial force and the most force will be put into the target when the blade is at 90degrees to the surface. I suspect the forwards positioned blade makes it easier to contact the surface perpendicularly while taking into account the complex arc and relative positions of strength of the pivot points along the way. Curvature of the blade is in part a way of reducing surface area and thus increasing pressure at the contact point.... improving penetration (not necessarily shear force which is different)