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An advantage of a wharncliffe blade is that it cuts with full power to the tip. This is due to the angle of force where the force is more likely to remain perpendicular to the target. This is especially advantageous in pocket knives where the blade length is short (relative to swords) and the impact relies more on a chopping motion instead of a slicing motion. In most pocket knives, there is not a lot of blade length to slice the blade against the target, which is generally much more efficient for cutting than chopping (e.g., it requires less force and is much easier to slice a tomato by slicing a knife vs. trying to press straight down against the tomato).

With regard to pocket knives, would a slight hawkbill profile be even more advantageous to a wharncliffe profile? It seems this would allow for more advantageous force vectors as long as the hawkbill is not too curved where it would impede stabbing. One situation where a hawkbill may be advantageous - imagine your wrist is bent backwards where a wharncliffe is moving parallel to the target. A hawkbill, under the same motion, would instead impart a force to the target.

A downside to a hawkbill profile is that it would impart forces that might cause a lock to fail - e.g., imparting force that causes a folding knife to close on one's fingers.

Another advantage of a hawkbill profile is that it increases the usable blade length without increasing the legal length. Generally, the blade length is measured in a straight line between the blade tip and either the end of the cutting edge or end of the blade stock. Since a hawkbill is curved, you gain more cutting edge relative to legal restrictions on blade length.

Would a slight recurve improve the Yojimbo/Yojumbo further? I would appreciate your thoughts.

The Yojimbo 2's blade was designed specifically with MBC principles in mind, so I don't think giving it a hawkbill profile (even a "slight hawkbill") would fit within that framework, at least based on what little I know of Janich's system.

From a pure utility/non-SD perspective however, I think a hybrid hawkbill/wharncliffe blade might be useful in certain situations.

Funnily enough, I often carry a Tasman Salt 2 SE (a serrated hawkbill) & a Yojimbo 2 (plain edge wharncliffe) at work: the former for cutting rope & pallet straps, the latter for more typical warehouse cutting tasks. I have often wondered if a knife that combined elements of both blade shapes would be a "best of both worlds"-type solution or if it would just be compromise solution that would be mediocre at both tasks.

chiselman wrote: ↑

Sat Sep 19, 2020 1:46 am

Another advantage of a hawkbill profile is that it increases the usable blade length without increasing the legal length. Generally, the blade length is measured in a straight line between the blade tip and either the end of the cutting edge or end of the blade stock. Since a hawkbill is curved, you gain more cutting edge relative to legal restrictions on blade length.

Would a slight recurve improve the Yojimbo/Yojumbo further? I would appreciate your thoughts.

It's not exactly what you are describing, but have you looked at the Matriarch 2's "reverse S" blade? Anecdotally, I've heard that recent releases of the Matriarch 2 have a less pronounced hawkbill tip (possibly a CQI feature) and it seems to me like it could be a good platform to test your ideas.

Could you possibly post a picture of a sketch of this blade shape you're describing? I'm interested.

There are definitely old sword variants that have a sickle/hawksbill configuration. They lack stabbiness, although one could say the same for any blade where the point is not in line with the grip.

Hi Chiselman,

Welcome to our forum.

sal

chiselman wrote: ↑

Sat Sep 19, 2020 1:46 am

A downside to a hawkbill profile is that it would impart forces that might cause a lock to fail - e.g., imparting force that causes a folding knife to close on one's fingers.

IMO, it would actually be the opposite; a hawkbill, during its proper and intended use, would be LESS likely than some other designs to have pressures placed on it that would cause the lock to fail. During pulling cuts, which the hawkbill is designed for, the blade is actually being forced more in the direction of the open position, as opposed to having heavy or sudden pressure placed on its blade spine.

Unless, perhaps, someone is trying to stab directly forward with it. Then, depending on the amount of curve to the blade, you’d be making contact with the end of the blade spine, which wouldn’t make any sense.

Jim

It completely depends on how you use a knife. Some people are really into hawkbills and karambits for lets just call it mbc stuff.

I would lean the opposite direction. Stabbing does damage. I am not a fan of giving up the ability to stab if I thought I might need to do it.

With that said, you need to be able to "use" any knife before having a preference. You need to have training.

James Y wrote: ↑

Sun Sep 20, 2020 1:42 pm

chiselman wrote: ↑

Sat Sep 19, 2020 1:46 am

A downside to a hawkbill profile is that it would impart forces that might cause a lock to fail - e.g., imparting force that causes a folding knife to close on one's fingers.

IMO, it would actually be the opposite; a hawkbill, during its proper and intended use, would be LESS likely than some other designs to have pressures placed on it that would cause the lock to fail. During pulling cuts, which the hawkbill is designed for, the blade is actually being forced more in the direction of the open position, as opposed to having heavy or sudden pressure placed on its blade spine.

Unless, perhaps, someone is trying to stab directly forward with it. Then, depending on the amount of curve to the blade, you’d be making contact with the end of the blade spine, which wouldn’t make any sense.

Jim

Agreed, at least in the ways I use my hawkbills. Generally any pressure from the cut would be pulling the blade open rather than closed. Using one to slash like a claw would have the same effect, although I've never used mine this way.

Hi Chiselman,

A lot of the performance characteristics of both of these blade patterns depend on what is the task?

Hey Julia,

Using a slashing motion with a Hawkbill really depends on the handle. If there is no "expansion" on the rear of the handle, and the hawkbill snags, if will pull the knife out of your hand.

sal

Once the blade begins to get a negative angle, it's going to have more leverage in a slashing arch motion. The problem with a hawkbill is that it's really easy to hook and snag and yank the knife out of your hand. The happy compromise here is probably a kukri, but even with those if you look at the handles they have a huge pommels to help you hang onto the handle better.

To be clear, I don't claim to know jack crap about self defense, I look at this stuff from a practical perspective, and I think if I were to end up in a knife fight where I had to defend my life with either a Yojimbo 2 (or Yojumbo) vs a Civilian or Spyderhawk I would hands down choose the Yojimbo because it will slash with authority, it's less likely to snag and get pulled from your hand, and most importantly it can also effectively thrust/stab. Much of these types of self defense attack motions loosely translate into everyday knife uses where these same qualities make a Yojimbo more versatile in day to day use than a Civilian or hawkbill.

The Spyderco P'Kal has a slight hawkbill curve, and as I understand it, is designed for stabbing and ripping motions in the reverse grip. I've long wondered if its handle contours would make it work comfortably for more mundane EDC tasks in a normal forward grip.

Hey, Chiselman and All:

Thanks for an interesting discussion.

Mikey177 beat me to the punch in referencing the P'Kal, which I believe has the exact blade shape Chiselman was describing. My testing experience relies primarily on using various shapes of training blades with partners and doing live-blade cutting on Pork Man and other targets. Training with partners validates the suitability of a particular blade shape for my preferred system of tactics. When I've tried radically curved hawkbills with MBC skills, they tend to snag on limbs, preventing a clean follow through and requiring you to "back off" on the cut to finish the motion.

When the same blade shape was used in live-blade cutting on Pork Man, the problem was even worse. If I started the cut with the heel of the edge, as the edge cut into the tissue, the blade point would hook over the dowel that simulated bone. At that point, I either had to articulate my wrist to an uncomfortable degree to contour around the dowel, or I had to back out of the cut.

Hawkbills with significant curve to the edge do have the ability to puncture with the point during a cutting action, much like an animal's claw. They then shear from the tip to the heel of the edge. This can be a very powerful cutting action, as long as you precisely control the depth of the initial penetration so you don't hit bone. That takes a lot of skill when targeting limbs. Radically curved hawkbills also completely lose the ability to thrust with conventional body mechanics and require specialized technique.

Hawkbills with a slight concave to the edge profile are much less prone to snagging and can offer slightly increased pressure at the very tip of the blade. The trade-off is a lower point profile that, again, makes thrusting with conventional technique more difficult. For edge-out applications, I wasn't able to tell much difference between their cutting performance and the performance of a good Wharncliffe. From an angular thrusting perspective, I found I often hit with the spine of the blade instead of the point. Again, it depended upon the exact profile of the knife.

Circling back to the P'Kal, it's important to understand the dynamics of the blade curve and their effect during various tactics. The curve of the P'Kal blade actually replicates the radius of the arc of the arm from elbow to hand--the motion of the backhand "P'Kal Jab." This puts the point below the bottom of the fist for maximum energy transfer and accuracy with that tactic. Interestingly, this is the same principle of the Warrior knife, but that arc was based on the full motion of the arm with the origin at the shoulder and incorporating a secondary bend at the elbow. Actual P'Kal tactics involve thrusting and then shearing or clearing on retraction. If you want to hook limbs, you articulate your wrist. If you want to cut, you simply pull back. While devastatingly effective, they're harder to express as true defensive actions in a self-defense context.

Where Chiselman's idea really shines is with non-locking folders. When I travel in Europe, where the carry of one-hand-opening, lock-blade folders is often illegal, I carry a hawkbill slipjoint as my folder. The slight concave curve of the edge amps up the blade's cutting power, keeps the blade open during use, and "reminds" me not to thrust with it. Even though it doesn't lock, all the core techniques of my MBC system can be done very effectively with it. During the weeks before I travel, I also train exclusively with a folding trainer that has a broken lock. It will "stay" open, but not "lock" open. I reprogram my tactics to eliminate thrusts altogether.

One final point--literally--is that many people are critical of the Yojimbo 2 because of its perceived tip weakness. Most of the people who complain about it don't actually own one and haven't broken a tip, but that's apparently irrelevant. Nevertheless, if you wanted to incorporate a slight hawkbill concave to the edge, you'd run the risk of making the tip more fragile--unless you added "meat" to the spine of the blade above it.

Like most things in life, it's a compromise... Again, thanks for a great discussion.

Stay safe,

Mike

Fascinating insight, Mike. Thank you!

Time for a Hawkbill UKPK, I think... The only Hawkbill slipjoints I’ve seen are pruning knives.