What is a Gravity Knife? Delving Into the Force Behind This Blade

Knives themselves are one of the oldest of all man-made tools in existence. As the ages have passed, knives have continued to evolve. Today there is an incredible array of different types of knives available for purchase. They range from the simple and utilitarian to the ornate and beautiful varieties, and their uses and functions are just as diverse. With all the types of knives out there today, you may be asking, "What is a gravity knife? How can it be used? And what is the legal status of these blades?" Keep reading as we delve into the answers to these and many other questions about gravity knives.

What Is a Gravity Knife?

To provide a basic definition of the category... a gravity knife is any blade that utilizes the force of gravity and/or a simple, physical action (such as a twist or spinning motion) from its wielder to open. A gravity knife typically features an easy-to-manipulate locking mechanism, but these tools should not be confused with switchblades, which open via a built-in mechanism.

To expose the blade on a typical gravity knife, the user can simply execute a slight movement of the thumb and then flick the blade into its extended position with relatively little effort. This means that the knife itself can be opened with one hand as opposed to two, making it highly versatile for quick deployment in various situations.

A Rugged History:
Gravity Knives Through the Ages

Gravity knives stab on a tree branch

Gravity knives were invented to solve a simple problem that ultimately helped save lives. During World War II, soldiers on both sides of the conflict would come to use the blade during paratrooper drops. All too often, the jump and landing wouldn't go precisely as planned, and paratroopers sometimes got tangled up upon landing. With a gravity knife, access to the blade could be gained with the simple use of one hand and a couple of fingers at most. So, this device's highly useful nature often made the difference between being stuck or stranded and getting on the move again to execute the mission.

The first German version of the gravity knife was first made by Luftwaffe Fallschirmjäger-Messer, who pioneered its design. Then George Ibberson & Co. of Sheffield, England, produced another popular version a few years later. This version was more or less the same design as its German counterpart, although the British version sported either a plastic or wooden handle, depending on the design.

Continued Regulation

Since the end of World War II, the knives have been both a convenience and a headache for law enforcement. It's often difficult to distinguish a gravity knife from some of its "cousins" among blades, especially the switchblade and the butterfly knife. Because of this challenge and the apparently subtle differences between them, different laws apply in various U.S. states, counties, and municipalities, and this sometimes makes determining the legality of a give knife difficult wherever you happen to live and work.

In New York City, for instance, the NYPD is constantly on the lookout for knives of this nature. Even if the user mainly uses their knife for work-related purposes, it's still conceivable that this individual may be arrested for 'criminal possession of a weapon' if found with a gravity knife in NYC. This could occur in a situation as simple as being subject to a common search on the subway.

Knowing the Laws and Using Discretion

Gravity Knife placed on a cut tree branch

It's important to research and learn what the knife laws are in your area before carrying a gravity knife around, whether you conceal it or plan to hang it on your belt. Whether we like them or not, the laws on the books are highly enforceable. And no matter what your intended use for the knife is, a 'weapon possession' charge could have different levels of severity of punishment depending on where you are.

Of course, this article is no substitute for legal advice, so if you have more nuanced questions about the in's and outs of the law where you reside, be sure to consult an attorney or another knowledgeable professional.

Quick Notes on Knife Safety

When evaluating or purchasing any type of knife you intend to carry with you, it's important to remember that its proper use is subject to important "best practices," It's also critical to realize and respect how dangerous these devices can be. Observing proper precautions and safety rules can help mitigate these inherent risks. So when using a gravity knife, or any knife ,for that matter always remember the following key points.

  1. Always remember to keep your knives sharp. Dull blades are more likely to slip because of having to apply more blunt force when using them. Knife maintenance is easily kept up by making sure to sharpen the blade at least once a year... or more often if use the blade frequently.

  2. Buying and using the right knife for your intended usage pattern is essential. There will always be judgment calls to make. You should consider a range of factors. What's the most appropriate size? What's the shape of the blade? What kind of edge does it have, and is that edge optimal or serviceable for materials you intend to cut t? The type of material you'll be trying to cut, score, or carve, for example, can make a huge difference when determining the proper tool to use. Only you can answer these questions, but they are worth asking every time you reach for a knife.

  3. Learn proper knife technique from someone with 'journeyman' or 'expert' status. This could be the person you buy your knife from or a trusted, knowledgeable friend. Usually the action you're performing will determine what kind of technique to use. Keep this in mind when consulting someone with that kind of expertise.

  4. When using a knife, make sure your hands are clean and dry.

  5. If the knife is not in use, make sure it's either closed or in its sheath, If you don't use a sheath, make sure your knife is put away in a matter that ensures when you reach for it, you won't get cut.

  6. Never cut or carve toward yourself or someone else.

  7. Be fully mindful and present when using your knife. Multi-tasking and split attention are the root causes of most knife accidents, whether serious or minor.

This is not an exhaustive list. There are other things to keep in mind when using a blade. Again, before attempting to use any kind of sharp object for practical, professional, or recreational use, always consult a professional beforehand if you do not already have the appropriate knowledge and experience.

What Types of Knives
Are Similar to a Gravity Knife?

When asking the question 'what is a gravity knife?', it's also useful to find out what a gravity knife is not. Because of the shapes and appearances of many gravity knives, they are commonly mistaken for other knife types considered more dangerous. Where you live and work, the laws may prohibit switchblades but not true gravity knives, for example. Let's proceed with a brief rundown of some other common knives, all of which are similar to gravity knives in at least one major respect, along with their key attributes and distinguishing features.

Butterfly Knives

A butterfly knife, also known as a Balisong, is a type of knife known for its blade's ability to be easily and thoroughly concealed. It may require a sequence of hand movements to open, but once opened, it locks into place and has a hilt that can be grasped with either one or two hands, depending on its size. Laws concerning ownership, concealment, and use of butterfly knives vary by state, and in some jurisdictions, there may be a pre-supposition that if you're carrying one, there is intent to use it to threaten or harm someone.

Many Balisong knive3s are valued as art and/or for their historical value. Even though the legality has changed over the years, the designs often carved or chiseled/welded into the metal work on a butterfly knife can be quite beautiful. However, their multi-step deployment actions and greater complexity overall make them markedly different from gravity knives.


Switchblade knives have mechanical opening capabilities (with most being button-triggered), and they are classified as concealed weapons, with harsh penalities for possession and concealment in many U.S. states. Again, the key distinction from a gravity knife in play here is the presence of a button or other quick-deployment mechanism that opens the knife, exposing the blade in a flash.

Depending on how it comes out of its shell or sheath, even the act of opening a switchblade can inflict damage. Generally speaking, gravity knives are much less of a risk to carry and deploy, and they operate similarly except for the action required to open one.

OTF Knives

This is a special variation of the switchblade in which a spring loaded mechanism causes the blade itself to emerge from a hole in the handle. OTF in this case stands for 'out-the-front.' They have a similar legal classification to other switchblades.

The Penny Knife

This is perhaps one of the most basic of all utility/multi-purpose knives, and its history is as old as its name. The reason it's called a 'penny knife' is because back when they were first invented in England, they could be bought or sold for one penny. These days the name is simply a placeholder for a basic utility knife. These knives have less risk associated with carrying them and have a variety of different uses as long as the task at hand doesn't require an enormous amount of effort to complete. It's not uncommon to see people with different types of penny knives on their key chains.


Gravity knife at the top of a solid rock with some cotton

So what is a gravity knife? Ultimately it's a tool that you can use for your own purposes. How you want it to look and what kinds of features it has are also up to you. Maybe there's a blunt end that you can use to hammer things, or a slot to cut twine or fishing line. We hope you now have a deeper understanding of what gravity knives can do and what to look for if you choose to purchase and carry one.

Featured Image: Image by HOerwin56 from Pixabay

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