What happens when a NERF dart breaks the SPEED OF SOUND?

oh but we're not gonna put this in a video right you just sealed your fate buddy Oh No hey guys recently I've been trying to make a super sonic nerf cannon and it's surprisingly hard to get one of these little one gram foam darts to go supersonic I got the idea after watching Jack oh whatever his video where he claims he can get a Nerf dart going Mach 2 1 3 5 1 which is pretty amazing if it's true I set out to make my own nerf gun even faster so I needed to upgrade his design he's using a solenoid valve which is probably pretty fast but not as fast as a burst disk is he uses 400 psi air and I'm gonna be using 600 psi helium I'm also going to be sucking all the air out of the barrel to create a vacuum on the inside of it otherwise when the Nerf dart goes down the barrel it encounters a lot of air resistance and steals some energy also I know it's been a really long time since I last posted in a video because this video just took a ton of time and energy and resources to make so I got to say thank you to Skillshare for sponsoring this video and thank you to everybody else for sticking around I really appreciate all of you thank you now it's time to start building that nerf gun I just found a lathe and I'm excited because it'll allow me to build cool things that I haven't been able to before but I'm still a little bit nervous about cutting threads fortunately it's not as hard as I thought it was let me show you first you select the threads per inch you want to cut then you set the threading dial to any number it doesn't really matter now all you got to do is engage the feed mechanism turn it on oh my god it's on fire how did that even happen the rest of the build was pretty uneventful so let's just skip ahead to the main attraction this is the supersonic nerf cannon it has three main parts pretty simple in design you have the pressure chamber barrel and vacuum accumulator and this is where you slept the vacuum from anyway so the pressure chamber just screws on and off just like this on the inside of the pressure chamber is where I put the burst disks I cut a group that holds an o-ring in there and keeps everything nice and airtight the burst disks are just cut from projector overhead film and I usually use about three of them to give them pressure of about 600 psi now getting up to 600 psi isn't easy so we're gonna need a special pump this is a special pump that I used to fill up my BB gun and it can pump up to 4,500 psi but it is very hard to do so it's time to do some tests and suddenly my brother was in town so he came over and we spent all day testing out the nerf gun first we tried it with just air and that got us about 1,100 feet per second which is pretty good that was definitely supersonic crack then we tried it with air and a vacuum on the barrel yeah I got us up to 1,200 feet per second 1,200 feet per second is really fast I mean we were able to punch through thin plywood with ease we could blow up tomatoes and even shatter glass with explosive results and this one's particularly cool I don't know what caused all those sparks but it was pretty neat I think it's because the Nerf dart is traveling so fast the air and the orange nose cone of the Nerf dart gets compressed so much it just catches on fire or ignites the rubber for a brief millisecond or something like that so naturally we tried shooting at it lighters but the flash is too brief for that unfortunately 1,200 feet per second isn't enough to punch through half-inch pine board though and also I can't get the Nerf dart to go any faster than that because if I just try to put more pressure in there the nerves are just comes out as blue confetti so I needed to figure out how can I make my gun faster and can I make my gun faster is there a limit to how fast you can push something so I need to answer that question and I did a bunch of research online and read a bunch of papers emailed some college professors and it turns out that projectile velocity is limited by how fast the gas that's pushing it can expand here's a graph that represents the speed the Nerf dart is traveling as it goes down the barrel say you launch it with a thousand psi by the time the Nerf dart reaches Mach 1 in the propellant gas the pressure behind it is only one-fifth of what it used to be so say you had an infinitely large pressure chamber that was pumped up to ten thousand psi as the Nerf dart travels down the barrel the pressure behind it begins to fall off even though the pressure in the chamber is unchanged so theoretically projectile speed is limited to five times the speed of sound but in practice it's usually about happiness eventually the pressure behind the Nerf dart will be so low that the pressure pushing it will equal to the force of the friction resisting it going forward and you will have no more acceleration okay one more thing I promise some of you might be wondering well why don't you use a supersonic nozzle behind the Nerf dart to make it go faster but this actually doesn't work turns out that nozzle can only be used to accelerate a projectile up to two point to four times the speed of sound in the driving gas and the speed of sound in compressed air is barely higher than it is normally anyway long story short instead of heavy old air we need to use the lighter gas like helium but why here you ask well the speed of sound in helium is three times higher than speed of sound in air so the pressure behind the Nerf dart will say higher for longer which brings us back to our nerf time whoo whoa that was a fun one all right now we've got a line of helium going right into the pump well awesome now we got the Nerf dart going 15 hundred feet per second and it can blast right through a half-inch pine board but unfortunately it's going so fast at a 1500 frames per second my camera only captures one frame of it we're gonna need a faster camera fortunately I met Matt from my X cameras and he's got a really amazing camera like the flagship model yeah the ice beats 720 yeah and that isn't a very amazing camera so we'll be able to see exactly what's going on with the Nerf dart and yeah blow some stuff up with it so the problem with the Nerf dart is it keeps exploding and of blue confetti out the other side of the barrel the pressure just goes into the Nerf dart and shoots the orange cap right off so we thought about reinforcing the Nerf dart so this is what we thought we wrap the Nerf dart in some shipping tape like the clear shipping packing tape and then we put a ear plug in the back of it so that way the pressure will just hit the ear plug and push it down the barrel instead of going into the dart and blowing the cap off of the dart so hopefully this will survive long enough to do some damage to a tomato which is our first target Andy found this about 10 feet away in the garage underneath the bench it's warm but that's probably from the lights did you notice how warm it is yeah the Nerf dart definitely went all the way through the tomato but it was vaporized in the process when we looked at the pieces of tomato afterwards it was just covered in blue confetti from the Nerf dart all right now it's time for the ultimate challenge do you think it'll go through it's gonna be a good good fight we're try to shoot through this half-inch pine board went through dude that was a lot of work so there's the entry there's the exit and to split the board right in half no that was oh oh what the that was a dart that wasn't in there it went clear through the pine board and just left a perfect hole through it which is pretty amazing happens pine board so now what we're doing to prove this is going supersonic we're using a technique called schlieren imaging which basically lets you see disturbances in the air so we have a mirror down there that's focused into the camera I don't know if you can see the mirror because it's kind of dark yeah but there's a point-source light source here just little tiny LED light that bounces over there and then you can see kind of the reflection of the LED can you see it yeah so it goes there and it goes into the camera and unless you see disturbances in the light first I'll show you the subsonic Nerf dart and you can just see it kind of goes through the air and there's not really too much disturbance in the air a little bit of stuff in front in the back of the nerve target but let's try the supersonic Nerf dart you can clearly see a shockwave in front of the Nerf dart and that's just called a bow shock and an interesting thing is you can tell how fast it's going by the angle of the shock wave coming off the front of the Nerf dart next we're gonna be looking at my BB gun which shoots subsonic I try to keep it subsonic but this one was an alloy pellet that was going almost or pretty much the speed of sound and you can see that the waves coming off of it are a lot more rounded they're not angular this thing is traveling just at the speed of sound since we have this fancy set up I thought we could try some other things this is my golf ball cannon my friend also tried clapping and yelling but it wasn't loud enough to see on the camera so let's try something a little bit louder nope it didn't blow up this was a mixture of nitrous oxide and propane and you could see some shock diamonds right when it blew I've also been curious how much gas escapes the propane torch when I light my golf ball cannon and it's not as much as I thought at all and of course we had to try the giant capacitor blowing up a banana oh that's satisfying you thanks for coming down man absolutely yeah and there is two PI X cameras for letting us is this super awesome high-speed camera yeah really helped us see what's going on with the Nerf darts as it came out like yeah they're for sure and we can see we can see go right through the wood and then we could see the shotgun with the schlieren imaging yeah how's awesome never done that before and it was so cool thank you for seeing the unseen is always fun yeah thank you and IX cameras for contributing that to the video well they never came down this video probably wouldn't have even been out for another six months with no videos so thanks for helping me get that video fine can't wait to see it yeah cool see you later sit earlier in the video I mentioned my partnership with skills share and if you don't know what skills share is it's an online learning community with over 17,000 classes and things like video editing film production app development and all kinds of other business classes a premium membership gives you unlimited access to high-quality classes taught by professionals in their fields so you can improve your skills and use them to unlock new opportunities doing the jobs you love Skillshare is also more affordable than most learning platforms out there with an annual subscription the feat comes down to less than ten dollars a month I mean come on if you're gonna spend 20 bucks on this you might as well spend 10 dollars on this just cuz you got a cool skin doesn't make you a good player trust me I know and hey you probably noticed my new logo and channel art well a good logo is very important that's pretty hard to do also so why not learn from the best errand wrap one has a series of design classes on Skillshare not only is it about logo design the series will also help you learn the basics of the program plus he's a pretty cool dude anyway the first 1,000 people to click the link below gets to three months of Skillshare premium so click that link below thanks for watching the backyard scientist ork

Channel: TheBackyardScientist

Views: 8,297,872

Rating: 4.88727 out of 5

Keywords: Nerf, Supersonic, Supersonic nerf, nerf gun, the backyard scientist, science, schrilian, high speed, high speed nerf, projectile speed, maximum projectile speed, physics

Id: s2yIMJ4iayg

Length: 11min 26sec (686 seconds)

Published: Sat Apr 28 2018

Reddit Comments

[u/Umikaloo]

I'm pretty sure that at those speeds, it's safe to call it a gun and not a blaster.

[u/northbay_nerfnoob]

He should 17/32 brass it.

[u/Ilive4airtime]

Ehh, 9/11, not good enough