Projectile devices?

I am thinking of making a projectile device. At the moment I have an unfinished bow that is drying out for a year, and a crossbow made out of office supplies. I was thinking of maybe a coil gun, but it seems a bit complicated. Any ideas?

Asked by dragonfathom 8 years ago


Coil gun projectiles?

Will solid discs (think coin-sized) work as coil-gun ammunition? Or is a hole in the centre absolutely required for the eddy-currents to flow?

Asked by Kiteman 7 years ago  |  last reply 7 years ago


How to calculate trajectory of projectile? Answered

How would I calculate the trajectory of a projectile with only the weight of the projectile, the velocity of the projectile at barrel, and angle of the barrel?  How did the artillery operators during WWII know how much powder to put or the angle of the barrel? Thanks for any help

Asked by electronicz 5 years ago  |  last reply 5 years ago



GPS Locator??

My brother and I are currently working on an air launcher projectile.  It is highly likely that it could go .5 to 1.5 miles.  We have the ability to test at this distance, however locating this costly projectile is likely to be difficult.  We have looked into gps trackers, however the cheapest one that would actually work was 500 dollars and if we had that kind of money we wouldn't need a gps tracker on the thing in the first place.  I just wondered if there was a quick and dirty way to make a short range locator.  I have heard of little bluetooth tracking stickers, but I wasn't quite sure if that would work to find a 1 foot long projectile in a square mile field.  This locator needs to be extremely shock resistant, fit in a container 7" by 1.5" and must weigh a minimal amount. We also are looking hopefully below 100 @most 150 dollars. 

Asked by jj.inc 5 years ago  |  last reply 5 years ago


Self loading confetti cannon Answered

I'm dressing up a golf cart for parade duty. I thought the "exhuast stacks" should be used for confetti cannons. However I don't want to stop jump out and dump more confetti down the pipe in the middle of the show. Any Ideas?

Asked by heathbar64 6 years ago  |  last reply 6 years ago


Specifics of building a multi-stage coilgun?

So I recently decided that I wanted to build a coilgun. I already knew how they function, and after some light research, I've got the main design already laid out. What I'm looking for now is some more detailed input on the exact power requirements, circuitry, etc. Specifically: Firing a standard .177 steel BB, I want to use many small coils in series as opposed to one/few large ones. From my understanding, this will provide better end speed while keeping each coil's power draw relatively lower, and thus safer. (Am I right about this?) How many coils should I use, what would be overkill, etc? Each coil will be triggered sequentially by a IR LED/photocell trigger system rigged through tiny holes drilled across the barrel. Will a simple on/off circuit suffice, or will the projectile pass by too quickly for the full charge to release? If so, I assume I need a system to trigger a full discharge when tripped. Correct or not, and if so, how? I'm also considering fitting an extra gate at the end to trigger a circuit to bleed any remaining charge. Ideas on this? What size of capacitors should I use, and how would I charge them? The only thing Google can seem to turn up is camera flash circuits, but I'd much rather have one tailor-built to the system's exact levels. I'm going to use a press/hold switch to charge them, and would like an automatic shutoff with an LED that comes on when they are charged, but turns off when I release the button. Kind of like a camera flash, actually. I'd like to fit it with a re-chargeable battery. What sort of power is required here? How many firings would I likely get per charge, etc? What sort of muzzle velocity can I expect? I don't want to kill bears with it, but soda cans would be nice. I don't want to waste my time fabricating it only to be able to stop it with my eyeball. Lastly, are there any other points of concern or things I should know? Thanks for any input, and if everything ends up coming together nicely, I'll be sure to properly document the process for everyone's enjoyment. :)

Posted by Skye Pyro 6 years ago  |  last reply 6 years ago


How to calculate projectile distance of a trebuchet? Answered

Hi! After looking on the net for calculations to predict the distance of a projectile launched by a trebuchet, I've not found anything useful. There are many variables and each one can be changed to alter the projectile distance and velocity. I am looking for a simple way to calculate this without calculus.Thanks again.?

Asked by 3.1415 10 years ago  |  last reply 6 years ago


Deriving the maximum range and angle of a projectile

In a thread in the Green group, AnarchistAsian and I were discussing his coil guns. I posed the question of what range he could get, and he asked me to go through the physics derivation. Here it is, simplified to require just algebra and trig.The kinetic energy of the projectile E = ½mv2, gives v = sqrt(2E/m) as the speed at launch. Let θ be the angle at which you launch (θ=0° is horizontal, θ=90° is straight up). Then you can decompose the speed into two components: vh = v cos(θ) is the horizontal speed,vv = v sin(θ) is the vertical speed.Gravity only pulls vertically, so the projectile's vertical speed will be slowed down until it reaches its maximum altitude, then it will fall back until it hits the ground. The horizontal speed will remain constant until it hits the ground and stops. To figure out the range, you need to know the time t that the projectile flies before it hits the ground; then the range is just R = vhtEnergy conservation guarantees that it's downward speed at the end is equal to its original upward speed, just with a change of sign. That also means that the total flight time of the projectile will be half going up and half going down. Once you determine how long it takes to reach the top of its flight, you're done; just double that answer :-)In the vertical direction, the maximum heightH = vvt - ½gt2(you need calculus to derive this result). From energy conservation, the initial kinetic energy in the vertical direction, Ev = ½mvv2 must equal the potential energy at the top of the flight, Pv = mgH:mgH = ½mvv2H = ½vv2/gSubstitute this on the left hand side of the trajectory expression,½vv2/g = vvt - ½gt2vv2 = 2gvvt - g2t2vv2 - 2gvvt + g2t2 = 0(vv - gt)2 = 0vv = gtSo, t = vv/g = v sin(θ)/g is the time to reach maximum height. Double that as discussed above, and you get the range R = 2 sin(θ) cos(θ) v/g.Work out the angle that gets you maximum range by just plugging in different angle values and finding the one that is biggest.

Posted by kelseymh 10 years ago  |  last reply 9 years ago


How do you make a proper Trebuchet sling?

My group is doing a Trebuchet for Engineering class and we've built it and it's ready to go. But it's missing the sling. I've tried making a sling but I feel I've been doing it completely wrong. Because the projectile (wooden ball) would either hit flat on the ground or never release. I'm also confused as to how the sling works, I realize one end is tied to the arm and another is free floating and unhooks and releases the projectile, but how exactly should you do this? Is there any good tutorials that don't leave out details, or at least explain it a little better? Any help is greatly appreciated and will prevent us from failing.

Posted by caseyweed 9 years ago  |  last reply 9 years ago


Is there something else beside a marshmallow i can shoot out of a marshmallow shooter?

Marshmallow shootin

Asked by mrelement 8 years ago  |  last reply 3 years ago


is there a to use the big burst of energy from a capacitor to have enough energy to make a photon or ray gun of sorts? Answered

How powerfull would a capacitor need to be to do this, an what is the relation between volts and uF?

Asked by mikmkt93 9 years ago  |  last reply 9 years ago


how to build a coil gun

Good day , I would like to build a coil gun but I don't want to use the disposable camera method I want to build my circuit from scratch  , I'm asking for some guidance , can you help me please 

Asked by franzakeem 4 years ago  |  last reply 4 years ago


Improvements/Questions on Launcher Design?

Using the picture as a base. What do you think about this design for a smoke/whatever else launcher. The barrel will be made of pvp and have a hinge connecting the two pieces. On the non-detachable side will be a hook, and the detachable side will have a "hook grabber". The hook is some sort of bendable material that will lock around the grabber. The gun part of the pvc will have a slit cut into, like the one in the picture. A spring will be glued down in the butt end, and the opposite end of the spring will have some small object attached to it. This object will also have a very small hook coming off of it. To load the gun you will detach the hook and push in the smoke grenade as far as possible. When you can no longer, you you attach a wire that is coming off of the little black box detailed in the picture to a mechanism that is attached to the trigger. You then close the front part to allow for better travel. When the trigger is pulled, it will detach from the blackbox on the spring, causing the spring to release all of its tension. The smoke grenade will, obviously, be propelled through. So, my questions. Would this seem like it would work viably? How much distance would you say it could get? The smoke grenades would weigh around 11oz . Is there any major flaws? I believe that some sort of spring guide will be needed. Are these possible to construct yourself? I haven't done any projects with springs before, most of my projectiles have been launched via combustion, so this is new for me. Should there be an additions? Also, the way in which the smoke grenade is going to ignite is a striker on the side of it, along with the inner edges of the end of the barrel having a striker on it. When they scrape up at the speed they will be at, they would ignite, and a fuse would catch the flame and ignite the smoke grenade. I have done this on other smaller designs. It doesn't have near a 100% success rate, but it still works the majority of the time. Any suggestions for changing this? 

Asked by Soldier62994 8 years ago  |  last reply 7 years ago



Is there and instructable for a projectile launcher make from knex that doesn't use rubber band propulsion?

Is there and instructable for a projectile launcher make from knex that doesn't use rubber band propulsion? I know that something like a catapult doesn't but i what something hand held? I would like a shotgun but a crossbow would do.

Asked by seanroberts 9 years ago  |  last reply 9 years ago


Zipdart help

I'm struggling to figure out why range is so low for this thing. The barrel ends right after the bands stop pushing the projectile, the effective length is over a foot for the barrel, and even after adding 15+ lbs of band power the projectiles are going maybe 40 ft no matter what projectile I use. Any ideas? 

Posted by Dreamwave 1 year ago  |  last reply 1 year ago


Could a coil gun's projectile escape earth's gravity?

If there were a Coil Gun, that was built to go across the United States and Canada border, for 2000km in a horizontal line, that would end at the end of a 'tunnel,' the projectile should hit escape velocity 11.2km/s and be out of the earth's gravity's field?Coil gun launch cost964 MEGA watts 10 cents per kwh (wholesale) from a power station$9,640,000.00 per launchNASA Space Shuttle launch costhttp://www.nasa.gov/centers/kennedy/about/information/shuttle_faq.html#10Q. How much does it cost to launch a Space Shuttle? A. The average cost to launch a Space Shuttle is about $450 million per missionhttps://www.instructables.com/answers/Space-Elevator-or-Lateral-Coil-Gun/

Asked by nfarrow 9 years ago  |  last reply 5 years ago


knex large gun help

Problem-i am building a large knex bazooka that needs a customized firing system. it needs to hold on to the projectile with some sort of fingers, which are to release when triggered from the rear of the holder, and the holder needs to ride in the rails of the gun, and it needs to be able to attach to a length of string. operation is-latch projectile in claws, pull both claw and projectile into barrel, pull to rear of barrel, stop motor, pull trigger, which through a series of levers will push to release on the back of the claw, launching the projectile. can anyone create such a claw as im stuck. ive got the gun, motor, gears, and projectiles, but i need some claw befor i build the trigger so they'll be compatible.

Posted by Nyanman 11 years ago  |  last reply 10 years ago


what websites have cheap components for coilguns?

I was just hopeing someone could help me find some websites that sell cheap electrical components like high voltage capacitors.

Asked by bobmcbob_345 9 years ago  |  last reply 9 years ago


How can I get a higher projectile velocity for my coilgun? Answered

I made a coilgun using 8 capacitors of 50V and 4700uf connected in parallel and powered by 4 batteries of 9V each. The coil is wound around a plastic tube over a length of 2 cm. However the projectile (an iron nail of 1 inch just popps out of the tube). How can I fire it at a higher velocity?   

Asked by coilgunfreak 5 years ago  |  last reply 5 years ago


Infrared Detector

Hello Everyone  I'm making a coil gun and not sure how to make a infrared detector, so when my projectile is going down the barrel an infreared sensor will detect the projectile and activate the next coil. Thanks Everyone 

Posted by jackopiny 4 years ago  |  last reply 4 years ago


Using LiPo batteries in coil guns

Hello all, this is my first post! I have been theorizing for a while about coilguns, and have been doing calculations. here is how it goes: A single Lithium polymer battery can hold up to 3.3 Ah and discharge at about 30c (safely). We multiply 3.3Ah by 30c and get 99 A of continuous discharge. That’s a LOT of current, but, it is still not enough to fire a good projectile. So, I’m planning on having four of these hooked up in parallel to give out 396A. This is quite a bit of dangerous current, so my wiring will have to be gauge-perfect. The magnetic field that this produces is about 9.9 teslas, as  twice much as your average MRI machine. Yes, I’m utilizing a miniature MRI to shoot stuff. If you want to know how much force an MRI puts out, here is a great video to show you https://www.youtube.com/watch?v=6BBx8BwLhqg. I am planning on having a 2,000 turn coil, with the average distance from the projectile being 1cm. The ammunition is going to be BB bullets, which means our cross-sectional area is at least 7.65*10-4m2. Using those numbers, the initial force on the BB is 3,015,030N. This is enough to lift up 25 semi-trucks. On paper, this seems magnificent. However, I’m accounting for about 2% efficiency, taken into account at this step, giving us 60,300N. This is still an enormous force to take to a .5g BB I’m implementing the Impulse to be .05s using standardized E = F * t,  this gives us 3,015 joules of energy. Huh. that’s way more than we should expect. Let’s take into account the 2% efficiency rating again, and we get a more realistic number: 60 joules. 60 joules is ridiculous for a BB pellet. We’ll use Ek = 1/2*m*V2 to solve for V. I got about 1,553 m/s. This is faster than most guns shoot regular bullets. I will be using a 2-stage setup, and will make sure to  use proper electrical equipment. My question to you is; How accurate are these calculations? if I build this thing, what can I excpect?

Posted by bjohnson45 4 years ago  |  last reply 4 years ago


Stun Arrow?

I know this sounds rambo but can it ezly be done? i wanna convert a basic aluminum hunting arrow into a stun projectile i was thinking mabey stacking some .5 farad caps? or would they even fit and rigging them to a disposable camera board just a thought

Posted by eckoside 6 years ago  |  last reply 6 years ago


projectile/ranged weapons (catapult, bow and arrow, rope dart)

Discuss ranged weapons

Posted by plasmaspy 10 years ago  |  last reply 8 years ago


Converting gravitational potential energy into air pressure to launch a projectile?

Hello my name is Aaron! I am a high school senior from northeastern Kentucky designing a pneumatic system of sorts for a science competition and need some help. I will be building a device that converts gravitational potential energy, from a falling mass, into air pressure (or possibly the movement of air depending on the design) to launch a projectile a specific distance (max distance needed is 8.25 m). What I am thinking about doing is using one double action pneumatic cylinder (DAPC) as a bellow in which a falling mass (max 3.500 kg at a max 90 cm) would strike its piston shaft, creating positive pressure within the system. With that positive pressure another DAPC’s piston would simultaneously strike our projectile sending it airborne in theory. Below there is an illustration of my idea, sorry about the poor quality. So what I need help determining is would this design work before I start buying parts? If so what approximate sizes should the two cylinders be and should they be different sizes to maximize the force exerted on the projectile? If you have any other ideas concerning the design or any questions about the project PLEASE feel free to share!!! Below are some of the design rules that pertain to this project along with some notes in italics about them. Thank you very much for your time in advance! ------------------------------------------------------------------------------------------------------------ Description:    -Prior to competition, teams will design, construct, and calibrate a single device capable of launching projectiles into a target and collect data regarding device parameters and performance. Design Constraints:    -The launching force must be entirely supplied by the gravitational potential energy from a falling mass less than or equal to 3.500 kg. Any device part whose potential energy decreases and provides launch energy is considered part of the mass. The mass may consist of multiple discrete parts, which together count as the total mass.    -During each launch, the gravitational potential energy must be converted to air pressure or air movement, which is then used to launch the projectile, either directly (e.g., pop gun style, etc.) or indirectly (e.g., using a pneumatic cylinder to swing an arm, etc.) All device air chambers must start at ambient air pressure and must automatically return to ambient air pressure.    -The launching device (would look similar to this with the adjustable angle to accommodate different ranges), including the projectile and all components, must fit within a 75.0 cm x 75.0 cm x 1.00 m box in ready-to-launch configuration, in any orientation chosen by the team. Weights used to stabilize the device must be within the box.    -The triggering device (would look something like this except elevated with a mass suspended ready to be released) in not considered part of the device and must not contribute energy to the launch. It must extend out of the launch area, allow for the competitors to remain at least 1.00 m away from the launch area, and does not need to return to the launch area after launch. The triggering device must not pose a danger to anyone due to flying parts or excessive movement outside the launch area.    -Teams must provide unmodified tennis, racquet, ping pong, and/or plastic practice golf balls to be used as projectiles. Teams may change projectiles for each launch.    -The launching device must be designed and operated in such a way to not damage or alter the floor.    -Electrical components are not allowed as part of the device or triggering device. The Competition:    -Two targets, designated by small marks on tape on the floor or panels lying on the floor, must be placed in front of and centered on an imaginary line parallel to the launch direction that bisects the launch are. Supervisors are encouraged to place sand, cat litter, or similar substance in the area around the targets to help indicate landing spots.    -The targets must be placed in front of the launch area at distances between 2.00 m and 8.00 m (in intervals of 10 cm). A distance of at least 2.00 m must separate the targets. Target distances must not be announced until after impound is over and must be the same for all teams. Room ceiling height should be considered when setting the distances.

Asked by ahoback 4 years ago  |  last reply 4 years ago


When building a Coilgun, do i want higher capacitance or voltage? Answered

What is needed in the capacitor bank. For example could i use a group of 8,000uF 80v or would i need higher voltages up to around 400v?

Asked by pyroten 9 years ago  |  last reply 9 years ago


how can i make a railgun with a taser?

Theres lots of instructables about how to use capacitors for it, but i have a high powered stun gun, with more volts than any camera circuit capacitor bank. 1,800,000 V or 1800 KV. i know there has to be a way to do this. considering a camera capacitor only has about 330 V.

Asked by mikmkt93 8 years ago  |  last reply 7 years ago


trebuchet? Answered

I'm thinking about building a 1 meter high (working) model of a trebuchet. does anyone have advice on this, like what can go wrong, which materials, lengths, etc. and what could be used as a projectile? note: i know perfectly what a trebuchet is, and how it works. i just don't have experience with model building.

Asked by necropolian 9 years ago  |  last reply 9 years ago


help modify my paintball gun shoot at 400 psi , or 600 fps, im trying to convert it to shoot special paint projectiles

Im trying to modify an a5 tipman marker to shoot a specialised paint projectile im creating , basically a sniper round of my own disign, but i cant get the gun to volicity i need. im not overyly into pmnumatic sytems as i should be, so i need help. i want at least five to six hundred fps, as the projectile is about twice as heavy as a regular paintball, so at 300 fps for a standard round i fiqure 600 fps for a round that is double its wiehgt, any help on how to acomplish this would be great,

Asked by joshuasanders89814 9 years ago  |  last reply 9 years ago


Need help from archery/ siege weapon people?

So im planning to make a ballista for a school project. I haven't learned all that graphing stuff yet, so how do i determine the range of a projectile launched according to it's angle launched, mass of prjectile, and draw weight? i suppose it would go somewhat like (Mass of projectile) x (n constant) x absolute value of ({angle launched - 45 degrees} x k constant ) x draw weight x g constant sorry, im not good at math. would it work if I just flung projectiles and recorded distances and graphed that? or would I have to calculate each thing seperately? please help 

Asked by picklepie159 9 years ago  |  last reply 9 years ago


Connecting the coil and circuit in coilgun

When i connect the coil with the circuit, there spark in the switch. Is it because the switch doesn't strong enough ? The projectile didn't fly.

Asked by shinizaki 9 years ago  |  last reply 9 years ago


More things steampunkable

I have an old electric stapler slide that i will find a home for in a steampunk rifle as the projectile slide, Thoughts on this coolness?

Posted by The Ideanator 9 years ago  |  last reply 5 years ago


The halo needler, is it possible?

Is it possible? The idea is very practical, a set of crystal-like needles that are somehow shredded into small projectiles which seem to be propelled by some form of energy or plasma or something. If thought through, I think it would be feasible. Recources? Do we have enough energy to create even a rough prototype? Can we create a way to propel these projectiles witout an explosion but rather with, as I said before, plasma or an energy source? Give me your thoughts...

Posted by vroom...vroom... 6 years ago  |  last reply 6 years ago


[Coil-gun]What is size coil will work best with my capacitors?

I am building a Multistage coil gun and have some 450v 1000uf capacitors. I understand it is important to have the wire size and amount of turns correspond to the capacitor for maximum performance. I have also figured out that the coil should be about twice as long as the projectile. My projectile will be part of a nail.What gauge wire should I use and how many turns should my coil be? 

Asked by eskibro830 5 years ago


How strong is the human skull? What material can simulate its strength?

I been experimenting with projectiles, and been wondering what can I use to simulate a human skull. I've been shooting at a 1\2 inch thick peice of wood board, the projectile made it all the way through easily. When aimed at someones head, do you think this could peirce the skull and damage the brain, or do you think the bullet will just get stuck? How strong is the human skull anyway?

Posted by IlluminatedAntichrist 10 years ago  |  last reply 4 years ago


convert coilgun to railgun? Answered

Can I convert the coilgun into a railgun by replacing the firing tube with two rails? Should the current pass through the rails only for a moment (as in the coilgun)? Which can accelerate a projectile to a higher velocity? 

Asked by coilgunfreak 5 years ago  |  last reply 5 years ago


Exotic ammo

I was looking at exotic gun ammo and pellet gun ammo and i was wondering if there was any exotic ammo you guys know of for any type of weapon the launches projectiles.

Posted by Iwantbigboom 7 years ago  |  last reply 7 years ago


electromagnetic gun

Can anyone help me makig an electromagnetic gun, to shoot projectiles at high speed using magnetic wire, capacitor etc, from where can i get a 300 volt capacitor = not from camera =,,,,,,,,,please help guys.......

Posted by ayushdubey12 6 years ago  |  last reply 6 years ago


Calculating Speed?

If you have an object with a mass of 2000 grams, and it has an average force of 635.029 kg pushing it for a distance of 6.096 meters before it becomes a free-flying projectile.  How fast is the object traveling after the 6 meters and how do you calculate it.

Asked by jj.inc 6 years ago  |  last reply 6 years ago


Best voltage for coil gun?

In my coil gun project I have 36 330v 120 uf flash capacitors. When I had them arranged in 4 banks of 9 linked together in series (.5*1200*1200*1000e-6 = 720J) the projectile could easily punch through cardboard. But when I tried to increase the power by making 7 banks of 5 giving me (.5*2100*2100*500e-6 = 1100J) the projectile has trouble getting through cardboard. The coil I am using is 50 feet of 22 gauge wire. Is there any thing that I am missing? Thanks.

Asked by eskibro830 6 years ago


air cannon burst switch or light switch help

I am trying to build an air cannon with a circuit that opens the solenoid valve for certain amount of time (0.5 seconds) when I hold down the button, or detects, with a photo gate, when the projective leaves and shuts down the solenoid. So far I have a circuit that will shut down the solenoid when the projectile reaches the end of the barrel, but the solenoid turns back on when the projectile clears the optical sensor(optical switch). This is because I would still be holding down the button. Any tips to get the solenoid to stay turned off? It should probably stay off until I hit a reset switch.

Posted by dogsrcool2me 11 years ago  |  last reply 11 years ago


knex trebuchet

I have made a knex trebuchet which is about 3 feet in length and 2 ft in height. The frame is strong. It can fire quite far but I'll get measurements tomorrow It can fire anything that fill fit unfortunately it doesn't use weights as a power source due to having nothing that could be heavy enough to fire it so, I put loads of rubber bands on it. its fire using string which is attached to the projectile and the other end of the string is connected to the arm which when is up right the string detaches and the projectile is released. At the moment is can fire about 20ft and gets loads of air time. about posting this: I will test it tomorrow and iron out any problems and make it perform better. after all of that I will post it. my thoughts: I think this is the best trebuchet to be posted :)

Posted by smidge147 10 years ago  |  last reply 6 years ago


High school senior project: something I can construct and donate to the physics department any suggestions?

I want to build a demonstration unit that would be useful for the physics teachers.  It has to be fairly challenging to construct, but not impossible or particularly costly.

Asked by danielsb7676 6 years ago  |  last reply 6 years ago


A Hybrid of Coil and Rail gun

So I said i'd throw this up in the comments section on Youtube not too long ago, and I don't like it when something easy and free doesn't happen. This is some ideas and observations that have to do with coil guns (mostly). I'm in the process of finishing up several projects, so my resources are kinda spread out. I should have a prototyped coil gun finished in 2-3 weeks though, so if this doesn't clear things up, hopefully that video will. I should point out, I am a chemist with expertise in biochemistry, not electrical engineering. Basically my idea is to combine a railgun and a coil gun for the expressed purpose of avoiding the pitfalls that a pure coilgun or a pure rail gun have. At present, none of the designs out there would be capable of competing with an actual gun. By mixing the two, i'm hoping to get something that might eventually be capable of doing so. So.. I've included a very poor drawing (I'm not an artist). The barebones circuit is sketched in the lower right hand corner. The gun barrel, which is a piece of aluminum tubing split into two pieces to sever as a rail system, is sketched in the upper left, and again in the middle figure to show how to integrate the coil and rail system. Looking at the circuit design, you can see that this starts off as a very basic capacitor-inductor circuit. The charge is purposefully allowed to trickle through the circuit until the coil reaches saturation and the capacitor(s) are charged. When the trigger is pushed, the inductor side of the circuit has to dump into the rail system to complete the full closed loop. Because of the ferromagnetic material (the brown stuff), the magnetic force persists for a while (that is to say, it has high reluctance). The ferromagnetic material does one other thing that is important here. It forces the middle of the coil to be far off center. The coil is pulling the projectile into the middle of the magnetic field, but that is not necessarily in the center of the winding. Adding ferrite, or other high reluctance material, towards the end of the barrel biases the field towards that end.  At the same time that the coil stops getting current, the rail system become active. This allows a charge to pass through the bullet/projectile, and, even though the majority of the force is going to be caused by the inductive coil, the rail system allows an eddy current to setup in the bullet. This does several things. First the bullet doesn't have to be iron, nickel, or cobalt. With a stray eddy current in the projectile, any conductive material will work. The advantage here is that once the current stops, the non-magnetic material stops being  to the magnetic field, preventing backwards acceleration of the projectile as it exits the barrel.  Second, Rail systems and coil systems are not often used because they are perpendicular to one another, but, this can be used to put spin on the projectile, in a similar manner to rifling in a barrel.  After the projectile is fired, the circuit is open, preventing excessive electrical discharge.  My circuit design is really badly drawn... =T if it needs more explanation please post up questions. 

Posted by Qcks 4 years ago  |  last reply 2 years ago


Knex "K*bot" competitions (kbotworld.com)

Http://www.kbotworld.com/ I was bored and decided to google "Knex". What I found was very interesting. Apparently there are competitions for Knex robots that do battle with each other. As I read this I thought about how us Knex gunners at Instructables could easily dominate these competitions; because we are the kings of Knex warfare. We could have a collaboration group based around K*bots, where we will post ideas and eventually have designs for the ultimate robot. Then when the competitions come around we could find somebody who lives closest to the competition to build the robot and enter on behalf of our collaboration.But there's a catch: There are rules, an one rule states that projectile weapons are banned. But I believe there are ways around this, as the exact ruling on this goes:"Projectile weapon systems which can launch a K'NEX part clear off the K*bot are banned due to safety reasons. Any other weapons systems which the organizers deem too dangerous will also not be permitted." This could easily be avoided by fixing the projectiles to the robot. For example: My cannon could use an extremely long bullet that has rods in the back of it, preventing it from ever leaving the robot while still delivering a deadly impact. But don't forget that weapons NOT based on guns will also be essential.So what do the rest of you think?

Posted by oodalumps 11 years ago  |  last reply 8 years ago


What happened to all the categories?

Just wondering what happened to a lot of the categories? When I used to come on this site there were a lot more, including the good 'ol section (forgot the name) dedicated to 'unrefined' projects (ie. constructing projectiles out of office supplies, constructing devices that could cause potential danger if misused, pyrotechnics, etc). Anyone know?

Posted by Rauffle 10 years ago  |  last reply 10 years ago


Is there an equation to figure a set amount of PSI to a recognizable, or commonly used force measurement?

What is/is there an equation to figure the speed a projectile travels, based on the PSI or force applied? What would this force be? k/h | fps | m/h | m/min. | k/min.|

Asked by PKTraceur 9 years ago  |  last reply 9 years ago


K'nex Chat

Get on and get into building better guns! Join me and other builders here. http://cbe002.chat.mibbit.com/?channel=%23kichat&server;=irc.darkmyst.org

Posted by Knex Lego Maniac 5 years ago  |  last reply 5 years ago


friend's project

A friend of mine is in the metals class at my school and he asked me for some ideas (since they can make whatever the want on this last project) on what his final project should be. He's thinking something like a trebuchet or something else that launches projectiles and causes pain (or just fun). It would be awesome if some of you had any ideas or instructables for his project. If you do, please tell me!

Posted by wingman246 11 years ago  |  last reply 11 years ago