Ballistic Engineering: Online and Face-to-face STEAM Lessons for Kids

(For Miguel, Julian and all my former colleagues in C.I. Miguel Caballero S.A.S. Thanks for the bulletproof memories!)

Hello! My name is Mario. I'm a STEAM teacher and a Maker. But during five months of my life, I had the privilege of working in one of the strangest places ever: a famous bulletproof clothes company.

How strange was that place? Well, imagine a factory where fancy bulletproof clothes are created for presidents and personalities, body armor for law enforcement officers, and heavy plates for military aircraft and small naval ships. It was like working in Q's laboratory and living in a "Mythbusters" marathon of only gun-related-myths episodes, all at the same time. I was in charge of the ballistic and quality test of the products. Even I was shot by my boss with a Magnum, a well-known tradition in that company (don't worry! I never show this video to my students.)

Now, as a STEAM teacher, I like to apply some of my little experience in that area, and teach my students (kids age 8-14 years old) about BALLISTICS!

Wait! Don't run away! Ballistics is not only weapons and forensics! I'm not training your kids to be assassins! (that would be cool, but not very ethical...)

Ballistics is basically the part of Physics that studies the launching, flight behavior and impact effects of projectiles. Probably your kids are already learning that in the curriculum of their school, specially in the part of gravity, velocity and trajectory of launched objects. And several classic STEAM projects use ballistics (catapults, marshmallow shooters, blowguns, bottle rockets, crossbows, and so on). However, a lot of teachers don't like to use the word "ballistics" because we are exposed mostly to the violent connotation of that word ("a ballistic missile was launched", "we are waiting for the ballistic analysis on the crime scene"). Ballistics is not only about launching a projectile, but also about how to stop it before it causes any serious damage.

This area has several real world applications, like:

• Sports: ballistics helps to understand how our favorite soccer or baseball player hits a ball and the forces acting over it. Also, it helps to design better balls, sport shoes and protection equipment to reduce the risks of trauma in catchers.
• Safety: any projected thing can become a projectile: a brick falling from a construction, a pebble hit by a lawnmower, an asteroid coming from the space. Even a bird flying against an airplane or a biker being projected from his motorbike during an accident behave like projectiles when they crash at that speed. Understanding ballistics helps scientist, engineers and designers to create better protection equipment and more resistant structures and materials for those situations.
• Space Exploration: well, you cannot design and launch a rocket without a deep knowledge in ballistics. Also, your starships, satellites and martian rovers need to be designed to resist the impact from meteoroids and space junk.
• Military, Law enforcement and personal protection: obviously, ballistics are involved not only in weapons design, but also en body armor to protect the lives of the persons exposed to that risk: cops, soldiers, humanitarian organizations deactivating landmines, bodyguards, presidents, and Steven Seagal (don't ask.)
• Forensics: probably the most popular application thanks to "CSI". Useful to determinate the homicide weapon, ammunition, angle, distance and all that technical blablabla we hear in the news channel and TV series.
• Rescue: helmets to protect firefighters and life guards. By the way, have you seen those sweet Batman-like line throwing guns used by rescuers during floods? BOOM! Ballistics!

In this instructable I will teach two STEAM Ballistic Engineering activities for kids age 8 to 14 years old. These activities have been tested with success:

• Air-powered Cannon (online lesson): this project will focus in the traditional application of ballistics (launching a projectile). I won't go deep in theory there, because as it was mentioned before, this is covered by Physics curriculum and hands-on projects. However, I will explain how this activity was created specifically for distance learning during pandemic times.
• Ballistic Protection Challenge (face-to-face lesson): Hopefully, the pandemic will be over on next year; schools will return to normality and we can do again this lesson. In this activity, the teacher will create a spring-powered launcher, and kids will be challenged to create a paper structure strong enough to stop the projectile before it hits an action figure. It's a risky activity, but with adequate safety measures, it's a fun one.

(DISCLAIMER: Some of the activities described in this instructable, specifically the second part "Ballistic Protection Challenge", involve shooting fast plastic projectiles in a classroom, with some risk of wounds and injuries. Follow all safety measures during all the steps of this activity and always use protective equipment. The author and Instructables.com are not accountable for any problem or legal issue derived from the execution of this activity, so replicate it under your own risk and responsibility. NOTE: the kids appearing in some of the photos and videos were recorded and photographed with their parents knowledge and consent, for the social media of our STEM center.)

In this exercise, designed for online education, kids will develop a pneumatic cannon that can launch a soft foam projectile. Each kid will have access to a bag with materials to create this prototype, and the teacher will explain step by step how to assemble it. At the end, students can experiment with different launching angles and see which one helps the projectile to fly further.

One of the biggest curriculum challenges that this pandemic brought for STEAM centers and teachers is how to teach engineering with online lessons.

Before COVID-19, I used to teach ballistics using classic projects from aerospace engineering curriculum, a professional straw-rocket launcher and a bottle-rocket launcher. However, some of these projects were not suitable for home learning; the mentioned specialized devices may cost between USD $50 AND $300, and for obvious reasons, it's not reasonable to send one per home. After some changes, I was still short on one project. I needed a solution for my online lessons and I needed it pronto!

I had to work with the following constraints:

• The materials of the project had to be sent in a bag to each home; and due to staff limitations, the bags had to be prepared by only one person (me).
• Easy to teach in front of a computer.
• Easy and safe to build for a student, with little or no assistance from parents during a 1-hour lesson, but not too easy that can be finished in 5 minutes.
• Materials had to be VERY affordable, reusable and easy to find in a time when our usual providers are in lock-down.
• No use of glue of any kind (specially hot glue and superglue) to avoid accidents, reduce costs and minimize risks of kids damaging their devices.
• WOW effect.
• Value for money. Parents are paying for STEAM lessons, and they expect projects to look like something that justifies the investment. I know, a good STEAM teacher can make a good lesson using just paper airplanes; but our clients won't pay for something they perceive their kids can do by themselves without assistance.

After some brainstorming, I created this syringe-rocket kit to use in my lessons. Even you can adjust the cannon's angle, for different ballistic-related experiments. I will show how to build two different versions of this project, each one with its respective benefits:

Mark 1: the prototype. Main advantage: kids can use it also as some kind of handheld "gun", adding some play value. Disadvantages: materials may be trickier to find depending of the country, and it's not as stable as the Mark 2.

Mark 2: the improved version. Main advantage: It has a protractor for more accurate experiments involving launching angles. Disadvantages: precut wooden blocks can be hard to get or to prepare for big groups of students. Recycled wood may work, but be ready for an afternoon cutting identical pieces for every student.

SUPPLIES

FOR BOTH VERSIONS:

• 1 Big syringe - 20 ml (drugstore)
• 1 Small syringe - 5 ml (drugstore)
• 1 wooden tongue depressor (drugstore)
• 1 rubber hose for the syringes (hardware store. Or you can buy and intravenous line in a drugstore, and cut it in segments)
• 1 screw for aluminum sheets, or 1 M3 screw with metal washer (hardware store)
• 1 cheap small screwdriver (hardware store). Don't forget to remind kids that SCISSORS AND SCREWDRIVERS ARE TOOLS, NOT TOYS (This sounds like an unnecessary advice, until you start seeing kids putting the scissors in their mouths.)
• 1 small roll of adhesive tape (any store)1 scissors (not provided in the materials bag. Probably kids have scissors at home)
• 1 projectile. I used a precut soft foam curler (from a beauty shop) with a hard plastic nucleus from a pen. You can also try with NERF darts. Simplest solution: the plunger from the small syringe will be available, so you can use the black rubber part as a projectile.

MARK 1 VARIANT:

• 1 Hard plastic hair curler (beauty store). Any plastic cylindrical container of the same dimensions may be used, but probably you will need to open some extra holes.
• 1 thin skewer stick for kebab (super market). The diameter must be enough to fit through the hard curler holes, in a tight way.

MARK 2 VARIANT:

• 1 protractor
• 1 wooden block, approximate dimensions: 2.5 cm x 2 cm x 12 cm
• Double sided tape

SPECIAL SAFETY CONSIDERATIONS:

• Some wooden pieces will need to be sent with pre-made holes.
• Use new syringes. It's preferable to send them still in their original package. However, remove the needles before sending them.

Take the foamy curler and carefully remove the metal wire inside. Probably you will need some pliers to cut or bend the hook at the end. Then cut a segment of the same length of the plastic piece you will stuff inside it. If you don't have the top part of a pen, you can use the cap that covers the needle from the syringe. The idea is to insert a piece to add some weight to the projectile and close completely the center, to avoid leaks. Or again, you can use the black rubber part from the smaller syringe's plunger.

Remove the plunger from the 5 ml syringe. Then, connect both syringes using the hose. It's important to check that both ends of the hose fit perfectly in the syringes, or kids will struggle to connect them. If that's the case, try to broaden each end of the hose, inserting some scissors or needle nose pliers.

To launch the projectile, first you must fill the 20 ml syringe with air. Then, insert one third of the projectile into the 5 ml syringe. Aim and press the big syringe until the projectile is launched, the same way a cork flies from a champagne bottle.

Take the tongue depressor and open three holes: one on each end and one on the center, being careful of not breaking the wood. The perfect tool to do that is a hole puncher. Actually, you will need only one hole. The other two are in case the kids want to experiment with different positions for the launcher, or if they accidentally break any part of the depressor.

Take the hard plastic hair curler. Probably it will come with a rubber band, so remove it. Confirm that the circular end opposite to the hole is clear, and open a small hole, where the aluminum-sheet screw will be inserted. You can use a small screwdriver, a drill with a small drill-bit or even, some pointy scissors. Don't make the hole too big, or the screw won't keep the tongue depressor in site.

Take the curler, the tongue depressor and the screw. Attach the depressor to the curler using the screwdriver.

Then, insert the kebab skewer through two of the curler's holes.

Attach the 5 ml syringe to the kebab skewer, using adhesive tape. Fasten the syringe in two points, so it doesn't move.

Fill the big syringe with air, insert the projectile and shoot!

Check if the protractor has a hole in the center point. If the hole is too small or absent, open it using pointy scissors or a drill. If the plastic is too fragile, use a soldering iron.

Take the tongue depressor and mark two holes: one at the end, aligned to the center point of the protractor; and the other one aligned to the small numbers in the degrees area. Then, open those holes using the hole puncher.

Take the wooden block and the protractor, mark the center point in the block, and drill a small hole where the screw can be screwed.

Stick two pieces of double-sided tape on the back of the protractor. Or if you prefer, send some segments of double-sided tape over a cardboard piece, so kids can stick them by themselves.

Remove the protective layer from the double-sided tape and stick the protractor to the wooden block, checking that the center point of the protractor is aligned with the previously drilled hole in the wooden block.

Attach the tongue depressor to the center point of the protractor, using the screw and a screwdriver.

Attach the 5 ml syringe to the tongue depressor, using adhesive tape. Fasten the syringe in two points, so it doesn't move.

Fill the big syringe with air, insert the projectile and shoot!

The advantage of this model is that you can see exactly which launching angle they are using and experiment with different trajectories. Kids can investigate which angle allows their projectile to fly the longest distance.

In this exercise, kids will develop a Ballistic Solution (a wall or castle) to stop a projectile before it can touch an action figure located behind that wall. Each kid will have access to only 20 sheets of A4 paper and 3 meters of masking tape. During Medieval times, cities had to resist sieges by armies with catapults, trebuchets and ballistas, so military engineers had to design and create better walls to resist those attacks. Also, armies had to develop armors for soldiers and horses, to protect them from enemy attacks. Kids will have between 30 and 40 minutes to complete their task. After that, the teacher will test each one of the ballistic solutions and how they protect the action figure.

A Ballistic Solution is a barrier, armor or plate able to absorb the kinetic energy from a projectile, in a way that it cannot harm the user. These barriers usually have special materials (like the famous Kevlar, invented by Stephanie Kwolek, that is just one of several types of "bulletproof" materials, like amides, poly-amides, acetylene, special ceramics and metals); and also, special configurations (the order you place the layers of materials.)

Some fun facts, probably not for kids, but to ruin your action movies forever (sorry!):

• The term "bulletproof vest" is not completely accurate. It's better to say "body armor", "ballistic vest" and "bullet-resistant vest".
• Ballistic protection is about compromises. The usual ballistic vest can protect you only against handguns. Only military grade vests with heavy ceramic plates can protect you against assault riffles, but they are heavier and recommended only if you are really entering a war-zone. The higher protection level you have, the heavier the armor will get, the slower you will become.
• Ballistic materials and efficiency can also be affected by humidity, weather conditions, fungus and even if you are wearing a larger size or a smaller size of vest. That's the reason ballistic vests have an expiration date, and it's not wise to wear them after that day.
• A ballistic vest is not a magical protection. It may be vulnerable to arrows, tasers, knives and other melee weapons. There are special vests against those threats; however, it increases weight and price.
• Every country has its own ballistic standards and levels, depending of the usual weapons you can find on the streets. An American ballistic vest (NIJ 0101.07 standard) may be useless in Russia (GOST R 50744-95 Standard), because they were subject to different tests and besides, post-soviets use armor-piercing bullets in their handguns, something not very common in United States handguns.
• In the TV Show "Titans", Jason Todd didn't shut up for the whole episode, boasting about how awesome, light and bulletproof his new Robin suit was because it had Zylon fibers. Zylon is an infamous material: it offers great ballistic protection, but it degrades very quick with humidity, long-term use, and temperature exposure. Basically, several nights sweating while he is fighting against the scum of Gotham city will make that body armor useless.
• Ballistic vests and plates are disposable after being shot (so, if you have a ballistic vest, don't test it, or it would become useless after that.)
• Ballistic vests need your body fat for full protection effect, so trying to use one as a shield without wearing it would be useless. Your breastbone (the bone protecting your heart) has low fat tissue; for that reason, that area needs a reinforcement. But that's not only for cops and soldiers; baseball players (catchers) have a type of ballistic vests to protect them from the lethal effects of a high-speed ball hitting their hearts.

Classroom Activity - Instructions and Safety measures:

This is a risky activity, but if you follow all instructions and safety measures, it will have a great WOW effect.

1. Before the lesson, build the Ballistic Tester: a spring-powered gun that will shoot the projectile against the ballistic solution. I disassembled mine to show you in the next steps how it was built. You can create your own solution (for more ideas, check this instructable, and also this one), but don't build it as a handgun! Doing that will increase the risk of shooting accidentally in the wrong direction, resting accuracy to the experiment and risking the life of you and your students. If you can fix it to the table using screws, and aiming it in one single direction, that would be ideal. Also, don't make a projectile with pointy parts.
2. Test your Ballistic Tester several times before the lesson, and check that the trigger is strong and doesn't release accidentally.
3. Align two tables as a Ballistic Test Area, marking the spot for your Ballistic Test. More or less 1 meter way, mark the Ballistic Solution spot. The action figure must be 10 cm away from the Ballistic Solution.
4. Using masking tape, mark a Safety Line, 2 meters away from the tables. If you can reinforce that area with other physical barriers (chairs, safety tape), that would be great. Nobody can enter the Testing Area without your permission, specially during the Ballistic Test.
5. When the lesson start, instruct your students about safety rules and the importance of following them. Also, tell them that the activity will be interrupted if anyone is not following the safety measures. If any of the attendants see that there is a risky situation or that someone is not following the rules, that kid of teacher has the power to shout "STOP THE TEST!"
6. After explaining them the activity, kids will have 20 sheets of A4 paper, 3 meters of masking tape and 30-40 minutes to use their imagination and create the best Ballistic Solution. After that, everyone will stay in the Safe Area and witness the test.
7. During the Ballistic Test, everybody must wear safety goggles. Safety face shields are ideal. Also, don't forget to keep a First Aid kit in the area.
8. Never aim or shoot the Ballistic Tester against persons or animals, not even as a joke! Also, always keep control of the Tester. Keep your face way of the cannon when you are loading it.
9. Participants will stick their Ballistic Solution to the respective spot, using adhesive tape.
10. Points will be awarded to each participant this way: 0 points if the projectile completely penetrates the Ballistic Solution and hits the action figure causing its fall, or if it blows away both of them; 1 point if the projectile doesn't penetrate the Ballistic Solution but makes it fall over or pushes away the action figure; 2 points if the Ballistic Solution completely deflects the projectile without stopping it, while the action figure is safe and standing; and 3 points if the Ballistic Solution completely stops the projectile, even with penetration of the barrier, with no harm to the still standing action figure (complete absorption of kinetic energy). Now, probably this sounded unfair but, why a penetrated barrier gives more score than a barrier that deflects the projectile? Well, a ricocheting bullet may still harm people unlucky enough to be in its trajectory. If you want a less violent example, think about a baseball or soccer goalkeeper's glove that protects the hand of the player, but how useless it would be if it allows the ball to slip. But if you want to give the same score in both cases, it's your choice.
11. Before the test, when each student is sticking their Ballistic Solution to the table; and after the test, and when you and the student are inspecting the results, the Ballistic Tester must be unloaded and you must keep all the projectiles in a safe area (better with you). This is to avoid getting hurt if the Tester activates itself (this may happen if the trigger is defective or when the plastic of the projectile starts to wear down after several shoots), or if some naughty kid decides to shoot it when you turn your back.
12. Only the teacher is allowed to activate or use the Ballistic Tester. All kids must be in the Safe Area.
13. Don't do this activity alone. Have an assistant that helps you writing the score in the whiteboard, supervising their kids when you have your full attention in the test, or calling for help in an emergency.
14. It's very unlikely the projectile has deadly force. However, the effects of it impacting a human face won't be nice at all. If you don't feel confident about this activity, your Ballistic Tester is not reliable, you don't see safety conditions are being fulfilled or kids are not behaving according to the rigor of this experiment, CANCEL THE ACTIVITY. It's better to change the project, reschedule the lesson or refund the money to the parents, than facing the health, psychological, reputational and legal consequences of an accident. It would be a great idea if parents sign a liability waiver before the lesson.

This is the Ballistic Tester I use in my experiments. It has four basic components:

• Projectile: I made mine using a plastic ceiling mount bracket for curtain (hardware store). If you cannot find one, a PVC pipe with a PVC cap attached at the end will do the trick.
• Base: I created it with an old PC screen base and the top case from a stapler, attached with bolts, washers and nuts.
• Spring Cannon: I used a plastic pipe from a NERF gun and a long spring I had in my workshop. You can use a bigger PVC pipe segment and PVC cap where the projectile can slide easily. The spring must be attached to the cannon using a screw. I also used zipties to attach the cannon to the base.
• Trigger: it was made using a plastic piece that can be coupled to the cannon, a metallic angle bracket to keep the projectile in position; and a bolt, a washer and two nuts to attach the bracket to the plastic piece. Also, I added a plastic cap to the bracket, so I don't hurt my finger when I release the trigger.

You will also need screwdrivers, pliers, cutters and the always useful Dremel rotary tool for drilling holes and cutting plastic and PVC parts.

Using the Dremel with a cutting disc, I created a notch in the pipe, not too small that the trigger cannot enter, and not too big that the projectile gets broken at the first launching. At least 5 mm of the trigger must fit inside this notch.

I placed the top case from the stapler over the PC base for screen, and attached them using bolts and nuts. I used the Dremel to drill the respective holes.

I inserted the spring inside the plastic pipe, and fixed it using a screw.

On the opposite end, I cut an notch, where the trigger is supposed to pass trough to lock the projectile.

I cut another notch on the plastic piece. I attached the metal bracket and test that it can rotate in a good way, and also, that it can pass through the notch.

At the end of the bracket, I placed a plastic piece for more comfort for the finger.

I inserted the canon inside the plastic part of the trigger until both notches were completely aligned. There was some space between both of the parts, so for a better fitting, I added some insulating tape to keep both parts in place and avoid movement. Adding screws for a safer union is advisable, unless they interfere with the spring and the projectile free movement.

I used two zipties to attach the cannon to the base: one passing through the hole near the spring's screw, and the other one attaching the middle part of the cannon to the stapler case. It's also advisable to use screws; however, the zipties were good enough.

Insert the projectile inside the canon. When the projectile and cannon notches are aligned, insert the trigger. Again: always keep your face away from the cannon when is loaded. Check that the projectile is completely locked in a stable way. Aim the cannon to the Ballistic Solution and when everything is ready, shoot!

That's all for the moment. Have fun and stay safe!