Everything You Need to Know About Gravity Knives

Ah, Gravity Knives. Very few knives garner the sheer interest that gravity knives do. I was never sure why. I’ve held dozens of them in my career at Blade HQ, and to me, they’re just another knife mechanism. Another method of opening a cutting tool for whatever jobs your daily life throws at you. To me, they have never been scary. In fact, I think they’re some of the safer knives out there, but more on that later. 

I think the intrigue comes from the name. Gravity is one of the four fundamental forces of physics – alongside electromagnetism and the strong and weak nuclear forces. Like the others, gravity is present whenever matter is present. It is inevitable, strong, and holds the universe together. Surely a knife with a name like that is super cool! 

Or maybe it’s just people remembering the trauma of constantly losing at Halo to some try-hard with a gravity hammer. Maybe a gravity knife has the same, well, gravity. 

But one way or the other, search engine analytics reveal that there are literally millions of you who want to know more about gravity knives, and I’m here to help you. Let’s do this! 

What is a Gravity Knife?

So far as knife enthusiasts are concerned, a gravity knife is any collapsible knife that is primarily opened by the force of gravity. Often, they have a mechanism that will keep them safely in their handle to prevent accidental opening. 

It is important to note that that definition excludes knives that can be opened by force of gravity but are designed to be opened another way. For example, many folding knives can be opened with a forceful flick of the wrist. Because these knives have thumb studs, thumb holes, flipper tabs, etc. they are not considered gravity knives by knife enthusiasts.

Gravity Knife History

It’s hard to say what the first gravity knife was, but the first to gain mainstream attention was the Flieger-Kappmesser (translates to “aviator’s knife”). This was a large folder designed for German Luftwaffe pilots and air crews. It had a locking blade that opened by force of gravity, as well as a marlinspike. The blade was used to extricate the parachutist from a tangled chute in an emergency. The marlinspike was to untangle and repack the parachute after a successful jump. 

The reason the Luftwaffe wanted a gravity knife is because it could open easily with only one hand and collapse well enough to fit in a pocket. That way it wasn’t a burden to carry on a cramped plane. 

In the 1990’s, the American High Altitude – Low Opening (HALO) jumpers needed a knife for the same purpose. But when they called Tony Marfione and asked for help, he didn’t give them a gravity knife. He gave them a legendary single-action OTF, the Microtech HALO. 

The HALO proves that for their original purpose of extricating their user, gravity knives have become antiquated. But those knives were still useful for a myriad of other tasks, and the gravity knife lives on today. 

Are Gravity Knives Safe?

Gravity knives are also safer for their user. Since they’re opened by the same force that grounds all of us, their action is intuitive. A gravity knife will never surprise you by how it behaves. No springs, no détentes, no funny business. 

Speaking of détentes, a folding knife has détente that holds the knife closed, and it must be overcome to launch a knife open. This puts a lot more force behind the knife to open it. If you’re not careful, that force can bury the knife in your thigh. Gravity knives work differently. To open one, you disengage the lock, and aim the knife down. Gravity will pull the blade out. If you want it fast, aim it straight down. If you want it slow, aim it at an angle and let the friction of the action slow it down. Either way, the knife will NEVER open any faster than 9.8 m/s².  

Unless you’re on Jupiter, in which case it could open at 24.79 m/s². But if you’re on Jupiter, you have much bigger problems than the speed of your knife opening. 

Are Gravity Knives Useful?

Gravity knives make use of the force that humans are most familiar with. Often when a user pulls out his or her knife, his or her hands are already full. It’s much easier to part with only one hand than two. That said, in today’s day and age, most pocket knives can be operated one-handed. 

Gravity knives offer the luxury of the user never having to touch the blade. This means that many gravity knives can be double-edged! Twice the edges, twice the edge retention, twice the cutting power. Double-edged blades also pierce much easier, so if you need to poke stuff, a gravity knife might be a good choice. 

What Are Some Good Gravity Knives?

Gravity knives aren’t super common, but they’re coming into vogue now more than ever. We expect to see some awesome new stuff in the upcoming months, but we’ll show off some of our favorites here. 

Reate EXO

This is one of the most unique knives I’ve ever held. When you disengage the lock, it allows the entire frame of the knife to drop out of the handle. The blade slides in and out via that frame. Once its open or closed, you can pull the frame back up with your fingers. It’s a great EDC knife, and an excellent conversation starter. 

Paragon Warlock

This one sets the standard of what a tactical gravity knife can be. It has a unique clam-shell opening mechanism. When you press on the pivot, the handle separates and the blade can swing free. When you let go, the handles snap back together. It’s a big, overbuilt knife, and with its dagger blade, it’s a formidable tactical companion. 

CIVIVI Elementum Button Lock

While not typically referred to as a gravity knife, the Elementum Button Lock does fit the definition. When you press the button, the blade can swing open or closed. It’s a very usable design, and it’s close enough to a traditional folder that it won’t turn any heads. 

AGA Campolin Dragonfly

If you’re on a budget, this is the gravity knife for you. It’s the least expensive knife on this list, and its mechanism is just plain fun. The blade is housed in the handle, and a swing cover keeps it there. With a flick of the wrist, the cover opens and lets the blade out. With another flick, the blade swings open and the swing cover turns into the locking mechanism. It’s a useful knife with an addictive action! 

Are Gravity Knives Legal?

The short answer is maybe. Knife laws are extremely vague and differ at federal and state levels. It’s hard to know what’s legal and what isn’t. Here at Blade HQ, we are committed to following the law, but the fact that the law is so confusing has caused us grief more than once. 

The best information I can give you is that gravity knives might be legal in some jurisdictions, and the only way you can find out is to seek qualified legal counsel in your area. You might try your luck with your district attorney’s office. Give them a call, and they will either answer your questions or point you to someone that can. 

If you’d like more information on knife legality, Knife Rights and the American Knife and Tool Institute can provide. 

Why Buy a Gravity Knife?

Gravity knives are useful, safe, and super cool. They are a unique and innovative contribution to the world’s cutlery collection, and they have some interesting history to boot. If a gravity knife speaks to you and you’re confident in its legality, you should pick one up! It will serve you well for decades. 

That said, gravity knives are a bit niche for my taste. If I could only have one knife for the rest of my life, I wouldn’t pick a gravity knife. But I am not burdened with such a decision, and I proudly have a gravity knife in my collection, and I hope to get a few more soon.