Pneumatic crossbow and other unusual arrows. Features of the use of bows and crossbows

Pneumatic can be not only a gun or a pistol, but also a crossbow. Today we are going to make the simplest model of a pneumatic crossbow. Naturally, what we create with you cannot be considered a full-fledged weapon, but rather this pneumatic crossbow will be only a model, on the basis of which handy craftsmen can make a more powerful and functional weapon. So let's get started.

To make a pneumatic crossbow, you need a block of wood about seventy centimeters long. You need to saw off a corner from the bar. This part will be designed for the handle of the air crossbow.

Next, we need to purchase a 60 ml (milliliter) syringe at the pharmacy. Actually, this syringe will be our pneumatic crossbow system. In a bar with a hacksaw, cut out a small slot in order to insert a protrusion for the fingers of the syringe. The syringe can be tied to the bar with ordinary adhesive tape (scotch tape, electrical tape).

Making a trigger mechanism for a pneumatic crossbow

Next, we pull the syringe plunger to the 40 ml mark and put a mark on the bar at the end of the stem stop plate.Near this mark on the bar (now it can already be called the bed of the pneumatic crossbow), screw a small piece of a wooden plate onto two self-tapping screws.

Next, you need to find a metal rod (rod) and drill a through hole through the plate and under its diameter. For the stem, you can use long bolts, which have a thread at the very end, which is then sawed off. However, if you have bolts with a solid thread along the entire length, then they can be grinded off on emery.

Now you need to cut out the trigger of the pneumatic crossbow from the same wooden block. At the edge of the trigger, we drill a hole for the diameter of the stem.Below the bed of the pneumatic crossbow we make an emphasis for the trigger lever.

As a stop, you can screw a narrow wooden strip onto the same self-tapping screws or glue a piece of the same bolt that we used to make the rod onto good glue. It remains to assemble a pneumatic crossbow, securing it with rubber.

Making a bowstring for a pneumatic crossbow

Now we need a medical tourniquet as a string. We measure the length as follows: we put it to the end of the crossbow bed and stretch it to the trigger rod, cut it off and fold it in half. Now we twist the medical tourniquet into a tube and wrap it with electrical tape at the edges and in two or three places along its entire length. We connect the edges of the bundle with a strong cord (thick silk thread) ten centimeters long. On the edge of the bundle, the cord is tightened with a knot, colloquially called a "stranglehold".

Making the barrel of a pneumatic crossbow

We cut off a piece of the dropper (it can also be purchased at the pharmacy, unless of course you have familiar health workers who have stocked up on such stuff for many years to come) and insert it into the tip of the syringe. We seal the connection with glue. Now we need to find a tube for the barrel. Any tube can be used, as long as it contains a bullet from pneumatics. A plastic shutter tube is ideal, but you can get your own ideas.

Insert the second end of the dropper into the tube and glue it again with glue. The tube-barrel is screwed to the stock of the pneumatic crossbow with the help of adhesive tape.

On the thrust plate of the syringe rod, cut (saw out) two triangular grooves so that they are opposite each other with their tops. This is necessary so that the bowstring cannot slip off the stem when fired. For better sliding, the syringe plunger is lubricated with oil.

The principle of the pneumatic crossbow

So, we finally make the assembly of our pneumatic crossbow. The thrust is put on the end of the crossbow stock (I think you guessed that for it there, too, it was necessary to cut a small groove) and is wound with a cord behind the syringe, putting it on the slots of the thrust plate of the syringe stem.

The air crossbow can now be charged. To do this, we pull back the piston rod of the syringe and hook it onto the trigger rod. We insert a charge into the barrel of the pneumatic crossbow. Take aim and press the trigger. The trigger pulls the rod down, the string is released, and the tourniquet pushes the piston forcefully into the syringe body. Under air pressure, the charge flies to the target.

Of course, if you don't have pneumatic bullets, you can use homemade crossbow darts instead.

Making darts for a pneumatic crossbow

Ordinary ear sticks are great for making pneumatic crossbow darts. You've probably seen these: plastic tubes at both ends, which are wound with cotton swabs. We remove the cotton wool from one end of the tube and insert a thick clamping needle there. The eye of the needle, despite the fact that it will fit tightly into the tube, is better to grease with glue. The hardened glue will prevent the needle from falling further into the tube when fired, nor from jumping out of it when removed from the target.

We insert the dart with the end on which a cotton swab remains into the barrel, and make a shot. Of course, after a few shots, the cotton will be gutted and the dart will become unusable, so I would advise you to come up with something more durable instead of a cotton thickening, but suitable for the diameter of the bore of the pneumatic crossbow. You can suggest your options. Good luck!

Produced by "Arcus Arrowstar" (pictured) the Austrian arms company SEMEX GmbH, founded in 1994 and providing supplies, in particular, to law enforcement agencies.

The energy source is a 16-gram can of liquefied carbon dioxide. It is possible to order an adapter for a much more familiar 12-gram. The pressure regulator in the basic version is set to 48 bar, which allows about 20 shots with a muzzle energy of 10 joules (a 17 joule version is also available). For Germany, where the familiar 7.5 Joule limit exists, the pressure is set using a 33 bar spring. This "F-variant" is already capable of firing 40 shots with a projectile speed of about 40 meters per second.

Now about these shells themselves. Weighing 9.5 grams, the hand has a caliber of 5.9 mm. The fact is that in Austria there are no restrictions on muzzle energy for such samples, but there is a 6 mm unlicensed caliber threshold.

Why did we suddenly remember this not-so-new shooter? Firstly, it is really quite original, nothing like it comes to mind. And secondly, our colleagues from the Kalashnikov magazine visited the IWA-2018 arms exhibition in Nuremberg and could not pass by the novelty from SEMEX GmbH - the Viper large-caliber arrow. In the photo, he is captured against the background of the "Arcus Arrowstar".

Indeed, judging by the arrows presented right there, the caliber is something about 9 mm, or even more. Alas, the manufacturer did not provide any specific performance characteristics of the "Viper". Which is understandable: if you look closely, you will notice the inscription "prototyp" on the body of the device.

It practically does not differ from spear guns, except that it uses not compressed air when cocking, but liquefied carbon dioxide in cans. That is, it is nothing more than an ordinary gas-cylinder pneumatic pistol, where the projectile is not bullets-balls, but arrows. Its sighting range with an arrow of 6 mm caliber and weighing 9.5 g is about 15 meters.

The fundamental difference from underwater weapons is that the latter cannot be used in the air. In a dense medium, which is water, the process of firing is "slow and sad", and on land the speed and, accordingly, shock loads on the seals and, in general, the entire mechanics, which are not designed for such a thing, will sharply increase. By the way, that is why it is impossible to shoot empty from powerful air rifles, bows and crossbows - without a bullet / arrow, which take and carry away a significant part of the destructive energy.

P.S. But you haven't seen yet another creation of the famous German inventor Jörg Sreiv. By the way, he created a six-barreled pneumatic crossbow from underwater guns - the original "Volcano Falanx" :)).

You can get acquainted with him in more detail on our VK page - Arbalet-airgun: crossbow pneumatics hunting weapon.

Pneumatic Line Throwers

In addition to the semi-toy samples described above, there are very serious products that perform no less serious tasks. These are, first of all, various kinds of line throwers used, for example, when mooring ships or by rescuers (in the photo, the rescue pneumatic line thrower "Owl").

His throwing range is limited by the length of the line - 100 m, no difference, vertically, horizontally or at any angle.

There are more long-range counterparts, for them we are talking about hundreds of meters, for example, like the ISTA-240.

The technique of firing from it is very similar to that for anti-tank grenade launchers.

Hunting pneumatic arrows

Of course, gunsmiths could not pass by the pneumatic principle.

A few years ago, a little excitement was caused by information about the appearance on the market (albeit foreign) of a certain superweapon - Airrow Stealth Model 8S1P (pictured)

Either a CO2 cylinder or compressed air was used as an energy source. This sub- $ 2,000 sample sent a 16-inch boom 2512 (Easton XX75) at speeds up to 600 fps, or over 180 m / s. Such indicators are unattainable even for modern block crossbows, a kind of "ceiling" for serial models is still 410 fps.

One point was completely unclear - what to do with the plumage? For devices operating at short distances, it is not necessary, but it does not interfere with water at all. But for the declared speeds of the Airrow Stealth, the distances must be hundreds of meters. It has been suggested that some cunning modifications of arrows are used here, which, like cruise missiles, opened the plumage after flying out of the barrel. As it turned out, there was a clue in the barrel - it was no coincidence that the manufacturers asked for such sums for their products, since the design turned out to be very complex.

In fact, in this case, the standard crossbow arrow acted as an over-caliber projectile and with the "heel" removed, turning into an ordinary aluminum tube, it was simply put on a thin inner barrel. Well, the thick outer one served as a kind of curly guide, inside which the feathers of the stabilizers and the blades of the hunting broadhead tips slid without being damaged.

By and large, the Airrow Stealth cannot be called a crossbow either. Yes, the technical solutions used in it are very ingenious, but nevertheless the device itself is nothing more than an air gun (gas-cylinder or pre-pumped), on the basis of which it was created. The manufacturing company, in fact, specializes in the production of air rifles. They are mostly known among hunters, as the model range covers all major calibers - from the classic .177 for the "air" to the mighty 38th.

The same can be said about the new product on the market - from the well-known manufacturer of air rifles and pistols, the Crosman company, also produced under the Benjamin brand.

This is a very real hunting machine, producing a solid 450 fps with a hunting arrow weighing 375 grains, or almost 140 m / s. These indicators are quite enough for this:

Of course it is impressive. And yet the deadly "Pioneer", like the previous model, is also not a crossbow. This is, in fact, the same air rifle with a pre-pumped PCP (see ""), which served as the basis for our hero. Here he is, dear, "Crosman Benjamin Bulldog .357 Realtree-Xtra":

Moreover, the domestic arms company "Dubrava" (formerly "Luftmaster"), known for its PCP rifles "Lesnik" and a novelty of the market, began accepting orders for the "Lesnik" pneumatic arrow launcher "Kashchei".

It is based on the same technical solutions as the Pioneer, only the price, for obvious reasons, is completely different. By the way, "Kashchei", so as not to conflict with weapons legislation, is certified as "a device for assembly, rescue and reconnaissance work in hard-to-reach places." Well, what a good idea. I'm a little familiar with the developer, I've seen test shots - impressive.

Topical insert. The first shots of "Kashchei" with a chronograph showed the following results: with a heavy 640-grain hunting arrow, the speed was 78 m / s, i.e. "Muzzle energy" of the order of 126 joules. With the 350 grain arrow, standard for many manufacturers of throwing weapons, speed indicators will grow to about 105 meters per second.

Supplement January 2020

Think, " Mountain air

By the way, since August 2016, even ordinary serial PCP rifles can also be used to throw heavy hunting crossbow bolts (see "").

On the picture "".

It would seem, what's the difference, what and how the projectile pushes, the main thing is that there was an arrow in its role. But, following this logic, APS (Special Submarine Assault Rifle) can be ranked among crossbows.

Something is clearly not right here ...

Unusual crossbows and bows

So far we lacked the main characteristic of classic arrow throwers - where is the bowstring !? It is she who transfers energy from elastic elements. And it doesn't have to be flexible shoulders. Since ancient times, weapons have been known that used, say, torsion bars.

In this role, rubber, like underwater crossbows, or a spring can also act. But the latter are both conventional twisted and gas, that is, pneumatic.

Spring-block "Cobra"

And such devices do exist. I already mentioned one of them in the article about. This is an ultra-compact spring-type compound bow "Cobra" on the base.

The author is the famous designer of mechanical bows Bogdan. He went to "Cobra" for more than one year, there were also "Phantom", "Rustle", and only God knows the number of intermediate options. The speed indicators of the product reach 85 m / s at the maximum tension force, which can be adjusted from 22 to 27 kgf. For such a tiny little one, this is very, very good.

Bogdan also had a Piranha spring-lever bow (not a blocker) and a Shadow mechanical bow, where rubber bands were used as elastic elements (pictured).

In general, our home-builders have a lot of similar designs, albeit not to such a degree of elaboration. But some go even further.

Unique "Vacuum Crossbow"

In the photo below the vacuum crossbow "Dust" (by the names of the authors). The device is patented, including in Canada.

The principle of operation is no longer based on high pressure, but, on the contrary, on the vacuum of air. That is, the classic "gas spring" is the opposite.

Unfortunately, the authors in the description do not indicate the speed of the arrow among the tactical and technical characteristics, limiting themselves only to the data on the thickness of the punched steel sheets. Judging by them, it is comparable to the average "blockman" with GOST shoulders at 43 kgf (95 lbs). On the personal site in the section "Experimental Crossbows" the authors gave approximately the same values.

In any case, a huge work has been done, the design turned out to be quite complex and really unique. If we abandon the problems of practical application, then the flight of engineering thought deserves the closest attention.

Well, very sharp "Praying Mantis"

Talisman Crossbows took a more traditional path. In her products, the nitrogen-filled gas spring works, as it should be, for compression, plus - the ability to adjust the "power" has been added.

The founder of the company Phil Abrahams, a mechanical engineer and designer by education and work experience, is also an experienced hunter who prefers precisely crossbows and air rifles. It was a sin not to combine the two approaches! And, it should be noted, it turned out very badly.

Interestingly, the nomenclature includes both block and recursive models. Both go under the general name "Mantis" ("Praying Mantis") - "Compound" and "Recurve". The pulling force is adjustable from 200 pounds for the first and 20 for the second to absolutely monstrous, especially for the block scheme, 300 lbs / 136 kgf! According to official information, the compound is capable of overclocking a 400-grain bolt up to 450 fps at maximum, and in the Elite version generally up to the sky-high 500 (152 m / s)! Moreover, booms weighing from 300 to - don't believe it - 1000 grain, or 65 grams, are allowed for use.

The area of ​​application is appropriate - hunting for deer, elk, bears. The price, the same for block and recursive, is also impressive: $ 2,358.

The handy-big-headed Samodelkin are haunted by the unique designs of antiquity. One of these is the multi-shot arrow launcher with more than two thousand years of Cho-ko-nu history:

By the way, the domestic arms company Dubrava (formerly Luftmaster), known for its Lesnik PCP rifles and the ultra-compact Anchutka, a new product on the market, has begun accepting orders for the Kashchei pneumatic shooter created on the basis of Lesnik.

It is based on the same technical solutions as the Pioneer, only the price, for obvious reasons, is completely different.

Supplement January 2020

Shooter "Mountain Air": our next response to the overseas "Pioneer"

My colleagues warned me ahead of time about the imminent start of production of the device presented below - almost two months ago, at the beginning of December 2019. Well, here's the long-awaited novelty on the arms market!

Think, " Mountain air"(Pictured) from the NKVD company could become a bestseller not only in our country. The same famous "Benjamin Pioneer Airbow" produces seemingly the same 450 fps, but with an arrow weighing only 375 grains. And at the same time it costs from $ 999, and not with us, unfortunately. Yes, with a set of arrows, but this is not ice - the bolts are original, “pioneer :)), ordinary crossbow bolts will not work ...

It is clear that it is difficult for any manufacturer to compete with the global “Crosman Corp” (now “Velocity Outdoor”, see “). But - honestly! - I would like to wish our colleagues success, including commercial. Moreover, they have another premiere on the way - a "universal soldier" :)) with interchangeable barrels, capable of acting both as a shooter and a classic PCP rifle.

P.S. So, according to just received strictly confidential information, "Mountain Air" just replaced the hero of Russian folk tales.

Someone came up with a bright thought: is it necessary to buy a new weapon at all and is it possible to somehow adapt existing rifles for hunting a big game? The idea of ​​its implementation was visited, of course, by the Americans. If only for the simple reason that they have a 50-caliber (12.7 mm) PCP pneumatics in completely free circulation, which allows, roughly speaking, to push a slightly modified arrow with a tail and a hunting tip into the barrel. Here's what they did.

In August 2016, the company "Air Venturi" presented its development - "Air Bolt" to the court of the shooting public.

The characteristic thickening on the “heel” (shank) of the arrows immediately catches the eye. It is this that creates a hermetic seal when the bolt is inserted into the barrel until it stops. This is exactly how it looks on the 50-caliber "Dragon Claw" produced by the well-known Russian airgunners of the South Korean company "Sam Yang".

It is clearly seen that the muzzle allows the use of not only ogival sports tips, but also hunting blade tips. True, the barrel length must be at least 22 inches, or 560 mm. Any 12.7mm PCP rifle will do.

At the same time, the owner of PCP pneumatics not only saves a thousand dollars or two on the purchase of additional "shooters", but also receives significant tactical and technical advantages over them, thanks to the exceptional power of serial 50-caliber rifles. The Big Bohr propels a 22-inch heavy hunting arrow weighing 430 grains (28 grams) to a mind-boggling 500 fps (feet per second), or 152 m / s. A set of 6 of these bolts costs about $ 145.

Let me remind you that the vast majority of modern hunting block crossbows give out a maximum of 410 fps, with about 350 grain arrows. The Pioneer Airbow can do more - the 375 grain arrow develops 450 fps - but it falls short of the Air Venturi's output. Really unique in design, the Airrow Stealth Model 8S1P is striking with its 600 fps (180 meters per second!), But it uses a lightweight 125-grain (no tip) 16-inch arrow, not very suitable for game hunting.

The explanation is simple. Both companies do not have in their lines powerful pneumatics at the level of the upper bar of the "Big Bore" class.

"Crosman", covering with its nomenclature, perhaps, all segments of the world pneumatic market, produces only one model of a really serious caliber - "Bulldog" in versions ".357" and "Bulldog Realtree Xtra". But 357 is far from being 50. "Bulldog", in fact, served as the basis for the creation of "" (pictured).

The Swivel Machine company specializes in hunting pneumatics in calibers from 177 (4.5 mm) to 38, that is, 9 mm. Therefore, the cunningly conceived and skillfully executed "" (in the photo below) in its initial performance characteristics could not compete with the 50 caliber characteristic of heavy machine guns.

"Air Venturi", as we can see, did not delve into the jungle of precise mechanics and, without affecting the classic design of standard PCP rifles, focused on the modification of ammunition. Borrowing, it seems, the idea of ​​sealing the boom shank from Krosman. The result is not bad: the accuracy of the Air Bolt is consistently about an inch (2.54 cm) at a thirty-meter distance, according to the test firing results.

As we have seen, the manufacturer initially focused exclusively on heavy duty 50 caliber (12.7 mm) rifles. And now it was the turn of their younger brothers.

So, " Seneca Recluse 500cc Ultimate Hunters Combo"(Pictured) is nothing more than the South Korean" Sam Yang Recluse ".357, that is, in 9 mm caliber. Actually, the contribution of "Air Venturi" was reduced to a complete set of the product with six arrows of its own design "Air Bolt" and a removable shako (quiver) for them. Well, and a quick-detachable muzzle attachment for hunting arrows with broadhead blade tips. Naturally, weapons can be fired both with them and with standard bullets. By the way, in 2018, "Air Venturi" released a 50-caliber double-barreled gun. « » , which is also capable of shooting shot!

The differences between new and old ammunition are immediately apparent. Most likely, the lack of feathering in the 9 mm versions will negatively affect the shooting performance.

Addition. November 2019

By the way, until recently, only one point remained unclear: even the diameter of the bore of a 50-caliber barrel is unlikely to allow inserting an arrow with a plumage. At least with the one shown in the company illustrations. Indeed, it is so. But rifles really shoot! How it turns out - look at the video.

brother 12.03.2014 - 12:18

Hello everybody. I hang out more often in pneumatics sections. Bows / crossbows are not my passion. Therefore, please do not cling to the terminology.

In general, there was a reason to think: should I buy a crossbow?
The sick head immediately began to think about it: is it possible to do it?
Of course, thoughts got in on how and from what, but how does it work for a bow / crossbow ...

As a result, a schematic diagram of a chain hoist crossbow was born on the GP.
The idea is in the picture, nothing tricky, you will understand everything yourself.

However, I will also mention a little theory, which led me to the schematic.
I came to the conclusion that in order to obtain the most effective crossbow, one must strive for 2 conditions:
- the wingspan should be made as small as possible;
- the springing element should have the smallest possible difference of forces cocked / uncocked.
A picture of the theory is attached.
I think I was far from the first to come to this conclusion. Polyspasses work on these principles.

And these conditions are perfectly suited to the polyspass on the GP.
With the effort of a good crossbow in the cocked state 80-100 kg, a "platoon" of 40-50 cm and in the presence of 2 "winches" of the chain hoist, our GP should provide an effort of 320-400 kg at a stroke of 10-13 cm.
It is quite possible to make such a GP. Moreover, with a difference in efforts of less than 10%, which is unlikely for the forces of other "springs" on bows and crossbows.

It turns out that by "cutting" the wingspan to 8-10 cm and constructing a GP with an effort difference of less than 10%, you can build a crossbow that will have no equal in the world.
(that's so modest 😊)
By the way, in the picture with the theory of the difference of efforts cocked / almost UNCocked from the "point of the arrow" to the roller of the chain hoist, I laid 20%. GP can be made with a smaller difference, but I suppose the "spring" will be much worse (even with the best samples).
So in practice, the efficiency of the GP-polyspas will be much greater than in the picture.

However, such a scheme may well be muddied up with a conventional linear coil spring instead of a GP. But the difference in effort, subsidence ...

I was not engaged in the construction of the prototype because I have not yet decided on the question: do I need a crossbow at all?
But I decided to throw the little idea to the masses - maybe it will be useful to someone.

brother 12.03.2014 - 12:51

I ran through the first 40 pages, looked at the pictures ...

I'm afraid that I have proposed something fundamentally new.
Something that, with the same cocking force, will fire an arrow at a speed at least 2 times faster than any of the options seen there.

And it will be much easier to do than most of the structures seen there.

Storch 03/12/2014 - 12:52

IMHO the second picture is wrong! There will be no gain in force! Blocks must be MOBILE !!! And so there is a direct transfer of effort.

brother 12.03.2014 - 12:57

I accept.
But this is even better - the GP is needed for less effort.

brother 12.03.2014 - 13:01

Efficiency comes from the very small scope of the "bow" and the corresponding angles of application of forces to the arrow during acceleration.
And also from the very small difference in spring forces charged / discharged, which is provided by the GP.

And the effort will increase on the rollers or not is not important.

PS: getting an effort of 100-150kg on the GP is generally a trifling matter.

PS2: and yes - by narrowing the scope of the bow we also increase the "acceleration distance" at which the acceleration force is applied to the arrow. Another factor FOR.

ADF 03/12/2014 - 13:11

You need a piece of chain hoist in it. Otherwise, in the above diagrams, the spring will mainly accelerate itself, and not the thrown body.

ADF 03/12/2014 - 13:23

0. Crossbows based on springs, including gas ones, are not new among homemade people. And they are all with blocks;
1. There is no question of where to get the spring on the bow. Because normal bows and crossbows are not made from springs (because of the danger when they split, because of the large moving mass). Shoulders on any (!) Bows and crossbows are easily bought, and whoever is not lazy - glued from composites with any required characteristics;
2. Non-linearity (although, according to Hooke's law, the force of the springs is just close to exactly linear in the entire operating range) is never a problem or a stumbling block.

brother 12.03.2014 - 13:29

bows and crossbows - do not make of springs

I asked you not to cling to the terminology: a polycarbonate spring remains a spring in its shape and principle of action.

Non-linearity (although, according to Hooke's law, the force of the springs is just close to exactly linear in the entire operating range) is never a problem or a stumbling block.

GP is also linear, there was no talk about it. It's about a small difference in effort.
In order to obtain a 10% difference in effort on a conventional spring, it must be "compressed" by 90% of its capacity in advance, in order to use only the range from 90 to 100%. For GP this is not a problem.

brother 12.03.2014 - 13:47

1 linear spring instead of 2 non-linear springs.

Here I meant the nonlinear trajectory of the point of application of the force. (at springs)

PS: the range of a classic bow narrows when cocked and increases accordingly when fired. Correspondingly changing the angles of application of forces and reducing the efficiency of boom acceleration.

PS2: I believe that the different deformation / force characteristics of two different bow halves is also a factor in shooting accuracy.

brother 12.03.2014 - 14:05

I knew it 😀

The truth is difficult, then how!
I think the crossbow will be simpler, and the scope can be reduced to a minimum. The schematic diagram about the theory clearly shows how much the swing affects the efficiency of overclocking.

PS: I guess that bow was designed for reasons of compactness, not overclocking efficiency, and just subconsciously went the right way.

PS2: by the way - I looked more closely at the pictures of that bow. There is a standard GPU from the rack without a headroom. The difference in efforts will be 25%. Conclusion: the designers did not think about efficiency at all.

gunslk 03/12/2014 - 14:49

If you have a head and hands, and saturation with pneuma, try without threads, so that the piston pushes the arrow right away, you will reach 200 m per second, there will be happiness.

brother 12.03.2014 - 15:09

And here a colleague is right:

the spring will accelerate mainly itself, and not the thrown body

the rod is heavy - the boom is light ...

The presence of a working winch doubles the force on the spring, but doubles the speed of the bowstring. 2 winches - 4 times ...
Polyspasses were not invented in vain ...
True speed transfer from bowstring to arrow is a separate topic (picture with theory).

I agree that in the very first picture of the winch I did not succeed. And I wanted as many as 2 pairs 😊

ADF 03/12/2014 - 15:09

gunslk
... immediately so that the piston pushes the arrow

And the piston will fly out after the arrow ... 😊

"rope" (passed through smart-ass blocks) in bows and crossbows is not needed for a simple reason. It converts the movement of a slow and massive spring into the fast movement of a much lighter boom.

In pneumatics, where gas springs are used, the link between the spring and the small bullet is air. The spring does not push the bullet directly there either - guess why! 😊

brother
... The difference in efforts will be 25%. Conclusion: the designers did not think about efficiency at all.

I say again: the (more uniform) effort throughout the entire working stroke is not critical for crossbows and bows. At the end of the working stroke of the bowstring, the entire structure (except for the arrow) must already be slowed down, accelerated - it is late and useless, effort is not needed. And the diagram of the accelerating force on the working section of the movement of the bowstring is perfectly tuned by eccentric blocks, especially since there are blocks this way and that, as they increase the coeff. transfer of energy from the shoulders to the projectile. On top crossbows (like so-15), the course of the ends of the shoulders is literally a few centimeters, with the course of the bowstring - half a meter or even more. And it will fire arrows with NSP 120-140 m / s.

Kainyn 03/12/2014 - 15:18

ADF
The spring does not push the bullet directly there either - guess why! 😊

thick, does not fit into the trunk?

gunslk 03/12/2014 - 15:36

Well, I didn’t write that the spring would push the thrown body, I wrote the piston.
Why can't the spring push the thick piston? Why can't this thick piston, pushing air in a thin channel, transform slow motion into fast one?
Why can't the last piston be light?
Why doesn't the last piston fly out with the bolt and detach?
Why would this piston not even fly out, but rest against the end of the barrel? (Such schemes have long been used in noiseless firearms)

The threads and shoulders limit the exit speed as the increase in speed approaches a blank shot. Decrease in shoulder span - loss of accuracy.

ADF 03/12/2014 - 15:50

The boom-butt piston is a classic speargun, however. 😛

brother 12.03.2014 - 15:59

Underwater, however ...

It may sound like a paradox to you, but under water a slow and heavy arrow is much more effective than a light one with a high initial speed.

gunslk 03/12/2014 - 16:07

Piston under the ass of the shot, under the ass of the bullet, ... the container ...
Yes, ... Probably more an underwater topic ...

brother 12.03.2014 - 16:10

The threads and shoulders limit the exit speed as the increase in speed approaches a blank shot.

And we will first increase the speed by 4 times, and then we will lose a little on the threads and shoulders 😊

Decrease in shoulder span - loss of accuracy.

If there are 2 arms (like 2 independent springs / springs) and they have different force curves, then YES.
Both with one and with 2 shoulders, a lot will depend on the quality of the rollers (their eccentricity, knocking on the bearings ...) ... but this is a separate topic ...

ADF 03/12/2014 - 17:24

brother
Underwater, however ...

It's exclusively about constructiveness.

brother 12.03.2014 - 17:59

It's exclusively about constructiveness.

How is a propeller different from a propeller? ...
Constructive without application ...

ADF 03/12/2014 - 18:14

brother
How is a propeller different from a propeller?

The fact that there are no propellers in the Russian technical language. Ask any pilot - he will immediately explain to you that the propeller is on Carlson's zeppe. 😀
It's like asking a sailor where he sailed. 😊

(call for offtopic)

delete 03/12/2014 - 22:42

what my themes set as an example

I, too, here bother with a crossbow on the GP

I even made a breadboard to test the theory

so far slowed down a little, with the design, but soon I will definitely embody it in metal

gunslk 03/14/2014 - 08:47

brother
And we will first increase the speed by 4 times, and then we will lose a little on the threads and shoulders
..

It is enough to increase the speed by at least 1.4 times, so that the threads and shoulders are scattered at different angles. They restrict b in a different way. 😀

brother 14.03.2014 - 10:13

STE mustache is understandable ...
Energy is also required to spin the rollers, the rope is longer and heavier (and it will also have to be accelerated). The higher the speed of the rope, the greater the angular speed of the rollers (the load on the bearings, which also slow down. It is no coincidence that the more severe the apparatus, the larger the diameter of its rollers ...).
But STE mustache common diseases of all polyspasses and a topic for another conversation.

brother 14.03.2014 - 10:29

By the way:

It is enough to increase the speed by at least 1.4 times, so that the threads and shoulders are scattered at different angles.

1.4 times relative to what?

I got on a video here, about a tactical polyspass ...
http://www.youtube.com/watch?v=chscJyx2GKU

The ratio of wingspan to platoon length was striking ...

ADF 03/14/2014 - 12:58

The TAC-15 is a fairly well-known top crossbow due to its aggressive advertising.
But the main thing in it is that the left and right shoulders move in opposite directions when fired and are synchronized so as not to cause unnecessary recoil and unnecessary vibrations in the system. Although this is not the only blocker where the shoulders jerk perpendicular to the direction of the shot.

brother 14.03.2014 - 15:06

Yes, I mean the speed that he gives to the arrow ...
To compare with it 1.4 times? Or what other?

In terms of

so that the threads and shoulders are scattered in different corners

brother 14.03.2014 - 15:17

The ratio of wingspan to platoon length was striking ...

I will demonstrate in pictures:
Cheap polyspass

The scope is almost twice the size of the platoon.

TAC15:

The platoon is clearly larger in scope.

Well, the diameter of the rollers ...

ADF 03/14/2014 - 15:18

Many top blockers shoot 120..140 m / s, kakbe. But I have not heard above 140 yet. Can you do 200 m / s? 😊

brother 14.03.2014 - 16:42

120 - regular crossbow arrows. I will not venture to name the exact mass, so as not to lie ...

gunslk 03/14/2014 - 22:03

brother
I saw a lot of ordinary crossbow arrows in the net: wooden, aluminum, 14 ", 17", 20 ", with different tips ...
Not to mention the short ones for crossbow pistols ...
Everything seems to be of very different masses ...

If all of them are fired at approximately the same speed, it can be fundamentally important for understanding the principle of the crossbow.
So I ask the regulars - is it so?

http://www.archery.ru/PDF/Predchuvstvie_poleta.pdf
Page 20

brother 17.03.2014 - 10:28

There is no answer to my question in the article.
Only confirmation of my assumption that arrows are of very different masses: from 15 to 40 grams, the difference in masses is more than 2 times.

The external ballistics of arrows and the speed with which they "break off the bow" of the same crossbow / bow are NOT the same at all.

Apparently chronographs are not held in high esteem by crossbowmen 😞

Soviet man 03/20/2014 - 01:16

About a year ago, on the vastness of YouTube, I met a topic about crossbows: http: //www.youtube.com/watch? V = 8h920whj4KA
might come in handy, not quite pneumatics, vacuum ... 😊

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The invention relates to pneumatic throwing weapons, in particular to crossbows, and can be used in sports shooting, hunting, as a weapon of self-defense or as a toy. The crossbow has a buttstock, a stock, an air accumulator with a rod extending by means of compressed gas with a block at the end. One end of the cable of the cable-block system is fixed on the pneumatic accumulator body, while the other is connected to the boom pusher. When the trigger is pressed, the cable pulls the pusher with the boom along the guide groove in the stock in the direction of the shot. EFFECT: high speed of boom departure. 3 ill.

The invention relates to pneumatic throwing weapons, in particular to crossbows, and can be used in sports shooting, hunting, as a weapon of self-defense, as a toy. Known crossbow for shooting arrows with a rigid tail, containing a butt, stock, trigger, pneumatic accumulator with a rod. This crossbow is known from FR 2380525 A1, cl. F 41 In 11/00, 13.10.1978 and by the greatest number of features in common with the claimed invention, is the closest analogue (prototype). However, this crossbow, due to its high inertia, does not allow obtaining a high speed of arrow departure. The technical problem to be solved by the invention is to increase the speed of the boom. This problem is solved due to the fact that a crossbow for firing arrows with a rigid tail unit, containing a butt, a stock, a trigger, a pneumatic accumulator with a rod, according to the invention is equipped with a boom pusher and a cable-block system including a block installed at the end of the rod and thrown over it a cable, with one end attached to the body of the pneumatic accumulator, and the other - to the boom pusher. The invention is illustrated by drawings, where Fig. 1 shows a crossbow in an uncocked state, in Fig. 2 - a crossbow in a cocked state, in Fig. 3 - section A-A in Fig. 1. The crossbow contains a butt 1, a stock 2 with a guide groove, a pneumatic accumulator 3 with a rod 4. The cable-block system includes a block 5 installed at the end of the rod 4, and a cable 6 thrown over it, one end attached to the body of the pneumatic accumulator 3. There is a pusher 7 on which fixed the other end of the cable 6. The crossbow has a trigger 8, an arrow 9. The crossbow works as follows. Force P is applied to the pusher 7 and additional force is applied to the rod 4. In this case, the pusher 7 is retracted and fixed by the trigger 8. After that, the boom 9 is installed in the bed 2. When the trigger is pressed, the trigger 8 releases the pusher 7 and the boom 9 goes forward. The strength of the battle depends on the pressure created in the pneumatic accumulator 3 when the crossbow is cocked. In this case, no gas is consumed. The energy of the compressed gas is used, i.e. a pneumatic accumulator with a rod extending due to compressed gas with a cable-block system moving the boom pusher along the groove.

Claim

A crossbow for shooting arrows with a rigid tail unit, containing a butt, a stock, a trigger mechanism, an air accumulator with a rod, characterized in that it is equipped with a boom pusher and a cable-block system, including a block installed at the end of the rod, and a cable thrown over it, fixed at one end on the body of the pneumatic accumulator, and the other on the boom pusher.