What Is A Gravity Knife? How Does It Work?

One of the most intriguing knives out there is the gravity knife.

It’s a knife that has a blade concealed in the handle, and the blade opens by the force of gravity.

It makes a really interesting sound when it’s released and it’s a blade that collectors, knife enthusiasts, and outdoor enthusiasts seek because of how useful they are and their cool design.

However, the knife has a pretty complex reputation as it’s prohibited in some countries, including the United States.

In this article, we’re taking a close look at what this knife is, its history and how it came to be, as well as why it’s illegal and if you can get one for yourself.

Keep reading to learn more!

What Is A Gravity Knife?

In short, a gravity knife is a tool with a folded blade in the handle.

And by the flick of the wrist and the help of some gravity the blade will get released.

The purpose of this knife is to allow users to release it with one hand, so if the other hand is busy they can still use the blade.

This is a tool used by a lot of different people from dockworkers all the way to carpenters.

A lot of these knives also have a sharp spear folded into the handle that people can use for a variety of things.

One of the most famous instances of a gravity knife being used is when parachuters get stuck in trees when landing.

Using only one hand, they can easily cut through their lines and get back on the ground.

These are also very practical outdoor tools since the blades are usually very high-quality and can be a great help when out on an adventure.

Sadly, while this is a very handy tool to have, the legality of it is pretty complex in a lot of countries, and not everyone can own one, but we’ll talk about that some more later.

A Brief History Of Gravity Knives

The original purpose of a gravity knife was for paratroopers who get stuck during their landing, since it will allow them to safely release the blade and cut themselves off their parachute.

And like a lot of things, this particular tool finds its roots in World War II.

It was developed in Germany since German soldiers at the time oftentimes found themselves stuck while landing on the ground.

And since most knives at the time required both hands to open and it would be really difficult if not impossible to use both hands when in a situation like that, the gravity knife mechanism was created to allow troopers to do everything with one hand.

Speed was a necessity since getting stuck in a tree for a prolonged amount of time puts soldiers at risk of getting caught and captured.

Eventually, a couple of German soldiers were caught by allied forces with these blades on them.

These tools were brought back to the United States and the United Kingdom after being confiscated and were later on called gravity knives since they used gravity to release the blade.

The invention was rather new to the allied forces.

In fact, the gravity knife came even before a reliable switchblade design was conceptualized.

The first knife of this kind was made by the German airforce and in Germany, it was called Luftwaffe Fallschirmjager-Messer.

After the British forces discovered the knife, the government ordered the Sheffield-based company, Ibberson & Co., to manufacture the same tools for the Special Operations Executive.

They eventually made 500 models that were then given to the government.

These versions of the tool had either smooth wood or textured plastic scales, which was the only thing that really set them apart from their German counterparts.

Since its inception, there has also been a rise in what is called “false gravity knives”.

These are blades that are able to be released by the force of gravity but wasn’t intended by the manufacturer to do so.

There are a lot of these types of knives out there, so make sure to thoroughly inspect the blade before getting one for yourself so you don’t end up with a false gravity knife.

How Does The Knife Work?

These knives work by relying on gravity or inertia to release the blade.

At the time of its invention, spring-loaded mechanisms had yet to be commonly used, so there was no chance of that being included in the design of this knife.

The only other blade that could be opened with one hand at the time was a combat knife, and those can be really bulky and probably wouldn’t be able to stay in its sheath for a parachute landing.

But the gravity knife is compact enough to fit in a zippered pocket, which was one of its main attractions.

To open the blade, all you have to do is point it to the ground and gravity will do its job.

When it isn’t in use, the lever mechanism built into the knife keeps it locked in place.

Once the blade is out, you can flip the lever back so it keeps the knife from slipping back in.

Even today’s modern versions of this tool use the same simple mechanism and if the lever is flipped, the blade will just slip out of the handle.

To close the knife, all you have to do is switch the lock and it will slide back into place and you can put it back in your pocket really easily.

What Are The Types Of Gravity Knives?

While the designs are usually consistent with these types of blades, there are a couple of different types that you would need to know about.

Standard

This is the common type of gravity knife that is almost identical to the ones used in WWII.

It looks like a standard folding knife with a lever on the side, and to open it, all you have to do is flip the lever and flick your wrist.

The intertia from the flick of the wrist causes the blade to come out of the knife while switching the lever will lock it in place and make sure that it doesn’t slide back into the handle.

Out The Front (OTF)

This is the second type of gravity knife that makes a couple of improvements over the original design used by soldiers.

The main difference between this variation of the knife and a standard one is that the blade is designed to withdraw back into the hilt.

On OTF models, you’ll usually find the lever on the front of the hilt.

Other Varieties

While those are the two main types out there, you can still stumble upon different variations on the gravity knife if you do enough exploring.

For example, the models used by British troops during the war looked a lot different than the German model because it had a smooth wooden finish, but other than that the design remained mostly the same.

Most people won’t know this, but technically, a butterfly knife can also be considered a gravity knife.

This is because it doesn’t use any mechanism to open up, instead, it uses inertia.

Can I Own A Gravity Knife?

Now it’s time to take a dive into the complicated history of this tool.

From WWII up until 1950, it was perfectly legal to own one, whether you were military personnel or a common citizen.

However, during the 1950s, the tool became very popular amongst young gangsters along with pocket knives and switchblades.

These tools were also seen a lot in movies and other media being promoted as “cool tools”.

It was because of this that lawmakers began questioning having these tools, as they saw them as dangerous objects to own.

So in 1954, the city of New York passed a law that made owning small knives and switchblades illegal.

And four years later, in 1958, gravity knives were included in the law and made illegal as well.

New York wasn’t the only state to pass a law like this, for example, Colorado banned the ownership of these tools as well and even tried to categorize other small blades as gravity knives, making those illegal as well.

The ban led to thousands of arrests over the years as many legislators believed that carrying one of these tools made someone more likely to be part of a gang.

However, most of the arrests made were of people who were simply using it as a utility tool.

In fact, a lot of the people arrested needed to have a small blade at work as it was an essential part of their tool kit.

In New York alone, thousands of people who needed to use a gravity knife at work were arrested not knowing that the knives were even illegal in the first place.

Because of that, the initial law that banned the knives lost public support, especially from law-abiding citizens who simply did not know that gravity knives were illegal.

The ambiguity of the law led to a lot of people who had no criminal intent whatsoever, to be arrested and punished.

Luckily, in 2019, the city of New York began reviewing the law.

A federal district court that analyzed the law concluded that the definition was too vague, which could lead to a lot of misinterpretation.

The federal district court declared that the law was unconstitutional and had to be repealed.

So in May of 2019, New York City declared that gravity knives were utility tools needed by a lot of people and legalized the use and ownership of these blades again.

While that may be great, most other states out there have yet to do the same, but New York City could be a good start.

In fact, after they were legalized in New York, the state of Ohio began reviewing their own ban on knives as well.

Now that public perception has largely shifted concerning these tools, a lot more people are interested in getting their hands on one themselves.

And depending on the state you live in, you might actually be able to!

So if you plan on buying a gravity knife to use as a utility tool, just remember that the laws on the possession and sale of these tools can vary from state to state, so make sure to read up on whatever laws your state might have on them before getting one for yourself.

If you don’t, you might risk getting arrested for breaking a law you didn’t know existed.

Where Can I Get A Gravity Knife?

Assuming you live in an area where these knives are legal, there are actually a couple of places you can get one yourself.

One popular option with a lot of enthusiasts is having one made by a bladesmith.

That way, they can specify all the features they want, and in some instances, even the materials to be used in construction.

However, not everyone has access to a bladesmith, and some might not even be able to craft a gravity knife themselves.

So if you don’t want to have one custom-made, you can always go to the wide variety of stores available online.

We recommend that if you do buy your knives online to go for trusted brands such as Paragon and AKC.

Paragon’s Warlock and Phoenix models are among the most popular with enthusiasts, while the AKC Gravit-E model has also gotten a lot of positive reviews.

Conclusion

So there you have it.

That’s about all you’ll need to know about gravity knives, from their history to the vague and complex ban on them, all the way to how you can get one yourself.

It’s very important to remember that state laws on these tools vary, so check carefully before going out and getting one yourself.

But if you’re lucky enough to be living in an area where these tools are legal, then all you’ll have to do to own one is head to your local knife shop or check out the options online.

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My name is David Strong. I'm a knife expert and a US Marine veteran. I used to fight in Iraq, so I gained lots of combat experience there, especially when it comes to combat, tactical, and outdoor knives. And this blog is where I share my expertise with you alongside my friend Andy.