Congrats, its the birth of a new meme! Two projectiles with opposite velocities smashing into each other would be cool to watch. Maybe use metal projectiles and see if any welding occurs during smashing.
+Zhengqun Koo As much as I would love to fire metal balls I don't have a safe way to catch them afterwards. As it is the ping pong balls will go through 3/4" plywood, a steel ball would have more energy than a rifle bullet!
It's still cool to smash two projectiles with exact opposite velocities, regardless of material, right? Maybe something that will deform instead of shatter, like solid polystyrene balls.
You can make a good fragmentation trap by using a double-walled (with a few inches between the walls) plywood box filled with sand. That will take the energy out of any projectile pretty quick, and it's cheap. I'd like to see a small (a couple of mm diameter) metal projectile riding on the front of the ping-pong ball, with a plate with a hole in it to catch the ping-pong ball but let the metal projectile through (basically a sabot catcher).
I'd like to see a DSLR or similar set to long exposure capture the flash in a dark room. The high-resolution image of the flash might reveal something interesting.
+JMMC1005 When I get another paddle I will try a long exposure. The duration seems to be enough that the ball move 1/2 it's own length so there will be some blurring but I think the paddle will be much more detailed.
Yeah, it won't be sharp. But I've found with similar things, the single frame captures a lot of info about how the gas is flowing because of the directionality of the blur. At worst, it might look artsy.
Good luck with the new channel. Perhaps you should upload all you supersonic cannon videos there as well. I'll give it some initial content for people that stumble upon it while browsing around.
+neowiza360 Thanks, the first one will be up on Sunday (and hopefully every one after that). If anything really weird happens I'll be doing the full write-ups here as usual.
On the issue of auto detonation, it seems that as you pointed out that the dimples seem to be a dependent factor. One could speculate that it was the friction of the polymer bumps that caused localized heating leading to the ignition of the material. To confirm that it is localized heating, a V shaped fixture could be used that has a similar material (sans bumps) on the inside of the V. When the ball is shot into the V there should be localized heating as the edge of the ball contacts the polymer material. A flash should be seen from the two contacting edges confirming the theory.
I have wondered what would happen if I fired the ball into a transparent cone, like you said, to get the most compression. I'm not sure which material I could use that would stand up.
Quite a clever way to get around the last bit of air problem, it looks like there is still a tiny bit of air trapped behind the burst disk as it's inflated rather than deflated but I doubt fixing that will add much to the final speed. Easy way to test what is igniting. Find non-nitro balls and fire those. Less common but they are out there. A sheet of thick, soft, open cell foam, moving up to 2" or so at least might be fun. See if you can punch a neat hole in something that normally deforms. :)
+Electra Flarefire I have a couple non-nitro (50, because eBay) but I found them to be less satisfying to fire, thanks for giving me a way to use them! You're right, once the ball is within an inch or two of the end I can do much, but it is a lot better now than my original. I think I have some foam around here already, I'll add it to "the list."
I imagine the volume of your vacuum accumulator has to be right-sized; too large, and there'll be an inrush of reverse-flow air when its burst disc ruptures; too small, and there'll be back pressure. Maybe some sort of muzzle break (brake?) at the end of the barrel that's in the vacuum accumulator might reduce the effects of any back pressure; say a coupling attached to a length of swiss-cheesed pipe; that way, as long as the projectile makes it to the break before the back pressure begins to build in the v-ac, the pressure will not have a concentrated vector to counter the forward momentum.
I was thinking about adding some kind of break/brake to disperse the extra air that comes behind the ball. Right now I think I have WAY too much propellant air but it ensures that there is constant acceleration right up until the ball hits the last membrane. I'm not sure if air rushing back in would slow the ball very much, maybe if I had some smoke at the exit end and filmed it as the ball left to see how quickly the air begins to rush in and interact with the ball. I wish I had mentioned it in the video but I figured you might like to know that the ball accelerates at over 3000Gs from one end of the barrel to the other and if it were to hit something really solid the average force would be just over 1.5tonns! Kinetic energy is awesome.
Cool that is great.For a space cannon i was thinking of using back pressure to open the vacuum doors at the mussel. Oh well. My suggestion for something new is have a "cold shaped charge" to accelerate a the ping ball. I think it would look like two or more pipe focused onto the back of the ping pong ball. The difficulty would to make burst disc brake at the same time.
If you still have this rig around and would like to use it on a new demo. I am very interested to see just how far it wire fire a ping pong ball, even modified ping pong balls that have a bit more mass. I'll probably build a version of this to test for myself but how I found this was by looking into ideas for throwing rope for pulling cable over long distances through areas that have 4' x 2' triangles. So far air cannons are the only ones you really see distance and ammo test with, vacuum cannons there's very little about distance and a whole lot about their destructive potential at the muzzle.
Well, originally I found out about your channel from AvE (He mentioned you in one of his videos). But this particular video was suggested to me by RU-vid because I've searched for vacuum cannons a few days ago.
@Nick Moore, this channel deserves more attention. I would suggest to do some collaboration using the supersonic canon with some big youtubers, such as physics girl, slowmoguy, etc. to draw more attention.
you should link the new channel in the description, i havent found it in a quick search and i think it might dicourage some people if they have to search for the new channel.
I know you say the targets can't be flammable or explosive, but I'm very curious to know whether the shock of impact would be enough to detonate a (milligram) quantity of tannerite. The ping-pong ball doesn't have much energy, and tannerite isn't easy to set off - yet the very high velocity means there'd be a pretty decent shock at impact. Provided the quantities are kept very small, I don't see it being particularly hazardous. You'd just need enough to hear or see a little flash.
+JMMC1005 I had thought of it but I all of my equipment is in doors, I would rather not have unknown magnitude explosions. I may try nitrocellulose laquor though, it is more like what I get with the ping-pong balls.
That's fair enough, though provided you go small enough it's going to contribute much less energy than the ping-pong ball itself has - shouldn't be hard to calculate the potential energy of a given quantity.
Im not sure, the glow happens with impacts on other materials but the brightest is always the paddle. I should try sugar cubes and quartz to see how bright they glow, thanks for the idea. Also, how did you find this video, I just got a burst of views today.
Very nice! Subscribed and looking forward to more, Im sure you will have plenty of creative things to show with it! A neat challenge might to be to try to decelerate the ball while keeping it a ball! bubble wrap? heavy gas cloud? Polystyrene bean-bag fill? could be interesting :)
So far I have successfully caught 1 ball but it was subsonic, most of them shatter even when they hit my balled up shop towel. I will definitely try to catch one without breaking it (in a visually fun way), thanks for the idea!
well done, really interesting interaction with the racket. ping pong ball vs ping pong ball, dissolved and put on a racket ? (: putting up a new channel, if so, link to this ?
+knglaser Added the link to the description, I'll have to see if I can warm up a ball enough to deform it flat, otherwise I can just hit another ball directly.
Assuming your using your new Chronos camera for slow mo, I noticed you said at 1:49 that you were running at 37,000 fps. Chronos only goes to 19,500 I think it was. Using a different camera or was this a mistake? Just wondered. Not being critical. I like all your videos.
David, the Chronos' creator, talked with the sensor manufacture and was able to increas the top frame rate to 38,565fps at 336x96px. The resolution is quite low but still very usable, my old Casio EX-F1 was only 1200fps at 336x96 and I still managed to get some interesting shots. Thanks for asking, I'm not sure if David ever mentioned the frame rate boost outside of the kickstarter comments.
So you are saying all the new cameras will have this to use or is it a software/hardware mod? I thought the video looked good for that frame rate. Would love to have that rate available once I have the camera but like I said before, that is a ways off I think for me. Just bought a pc for $2600. Need to pay that off asap.
+55Ramius As far as I know it is now a standard feature added to the base software. I was surprised as well at the quality, the real hard part is getting enough light. I had 120w of LEDs about 6inches away to film that.
This is amazing! Have you thought of filling the pressure chamber with a light gas, like helium, to reach even higher velocities? Or preheating it with a heat gun? As for the target, how about something triboluminescent, like a block of sugar soaked with some wintergreen oil? Looking forward to seeing more of this!
I had thought about it but im not sure about the high speed camera, it's on the list and whether the high speed sees the flash or not I'll bet the normal one will see it. I have thought of using helium but getting a tank and regulator is pricey around here. If the cannon channel takes off I will be putting money back into the project to see if I can get up to the world record (over 800m/s)!
I'll try to advertise it then! Also, as an interesting target : how about a thick metal plate, thick enough so that it will easily withstand the impact. (like the back of a pan). That way, we can see the ball deforming under the impact.
A friend of mine is going to let me borrow a big hunk of lead. I plan on melting it into a think sheet to see if the ball can deform it at all. I also have a hardened steel brick around here somewhere, I'll give that a shot too.
What would be the difference between a vacuum cannon with -14.7 psig compared to a compressed air cannon with +14.7 psig? Let's say, same projectile weight and size? What would be their impact force and exit velocity from the tube?
The biggest change isn't really the extra pressure it's the weight. Because the ping pong ball is so light the weight of the air ahead of it is comparable to it's own. So just putting lots of pressure behind it would mean that you have to push not only the ball but the air in front of the ball as well. By vacuuming out the barrel the ball can accelerate un-restricted until it comes out of the barrel.
+Nick Moore What about the impact force when the projectile is out of the cannon and hit something. Let's say the vacuum cannon barrel is 10ft long and it's target is 15ft away from the tip of the cannon. Then the 14.7psig compressed air cannon barrel is 10ft long and the target is 5ft away from the tip of the cannon. Will they have the same impact force since they'll both be pushing/hitting 15ft worth of air molecules in front of the projectile? If not, then how many times stronger will the impact of the vacuum cannon hit the target vs the compressed air cannon. And how many psi of compressed air do I need to equal the impact of the vacuum cannon?
I'm not really sure. I think it's possible to get the ball up to any speed using just compressed air but the pressure required goes up fast. The other limit is how much you can accelerate the ball, right now the balls are pulling more than 3000Gs in the barrel (the ball weighs 18lbs for that time!), much more than that and they will shatter.
I have been trying to get a retroreflective sheet to work in a schlieren setup for a while as the mirrors required for a normal setup start around $300. If I can ever get it to work I will share it for sure!
+Y2KNW Funny you should mention spam, it's 80 years old this year and I blew a can away last weekend to celebrate, the video should be ready and up near the end of the month!
I thought you said no hazardous or poisonous materials? There could have been enough botulin toxin in that nasty old spam can to wipe out Southern Ontario. :)
I'm curious about the difference in damage between the ping pong ball itself and the air that comes after. A simple experiment would be to shoot the same material twice once with a ball and once with nothing (but air) to see how they differ.
Thank you for this. I've been getting frustrated with my cannon. -28 inHG and the ball only even makes it out of the barrel half of the time. That accumulator will solve that problem. Not sure how it's sleeved though....oh well, I'll figure it out. Thanks
Regarding that flash of light, take a look at this ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-k5MORochIDw.htmlm8s He shot a prince Rupert's drop with ak47, and there was a flash of light too!
Different charging gasses ought to affect the projectile velocity; I think Helium is supposed to work rather well in these devices due to it's low viscosity and inertia, but I suspect perhaps some of the heavier gasses (CO2, water vapour) might work better for accelerating heavier projectiles...
The record holder (over 800m/s!) has been using helium on a very similar cannon, if I can ever get my hands on a cheap tank and regulaor I will be switching over. Water vapour might work well in a slightly different application if it were superheated and then released like the Mythbusters hot-water tank rocket.
I'm confused by this. Isn't the maximum rate of compressed air exactly the speed of sound? How can you accelerate something faster than that without using another gas such as helium? I don't doubt you can since there are many other reports of supersonic+ vacuum cannons using just compressed air, I just dont understand how it's possible.
I'm still not 100% sure how the speed limit works for vacuum cannons. I suspect that in a very short barrel with no ball it might be possible to have air rush in at higher than mach 1 but without enough force to do any work. As the barrel gets longer the atmospheric pressure has to move more and more air through the length and you end up with a lower average speed. I found lots of conflicting ideas about how and if it is possible/impossible to get a mach 1 cannon with vacuum alone.
So now that you have developed your own particle...er, ping pong ball.. accelerator, I assume the next step is to try to raise the energies sufficiently to form more massive ping pong balls from collisions? In any case, isn't the classic target ballistics gel?
Yes! I am working on getting some for less than the $50 a block it goes for online, probably use bulk powder and make my own. With any luck I will have ping-pong-helium within a few months, the guys at the LHC better look out.
I just discovered this video and realized you designed the same vacuum chamber at the end of the barrel like the ones they made at smarter everyday. Only that you did it 3 years earlier.
Wow, I somehow missed this when you first posted it. Very clever design with the additional accumulation chamber up by the muzzle! How do you make the burst discs? Or do you buy them?
The exit end is just one layer of mylar, the high pressure one is 3 layers, tuck tape, mylar and tuck tape again. There is also a little nichrome wire between the wires for triggering.
Hey. I was just thinking if you wanted to get the speed of that ball up you ought to consider decreasing the temperature of the air and maybe using air with high percentages of carbon dioxide. The kinetic energy of the air is proportional to its mass so if you up that you may be able to significantly increase the speed of the ball. Most of the other readily purchasable gasses much heavier than air are super flammable so that would most likely be a disaster but maybe a non flammable once would increase that speed by even greater amounts. Doing this with an isolated system of a shitload of carbon dioxide might just increase the speed by nearly 70%. You should try it.
I have heard arguments in both direction for the "weight" of the propellant gas. Helium is used in NASA's "Light Gas Guns" that fire steel BBs up to 7km/s and in the world record holding ping pong cannon which is over 800m/s. I do have access to cheap CO2 though so I might give it a try.
You need to have a picture of the ball going through the racket.. or something like that... you have are video good enough for the 20 millions views!! but you need to spice it up man!!!
This is amazing! Seeing something as light as a ping pong ball obliterate just about anything. Out of curiosity, does the ping pong ball have a hole in it, and does the air inside of it also evacuate? If so I would be curious to see what would happen if you were to seal it completely!
+rowan Bloemhof The balls are completely sealed as far as I can tell, when they are manufactured the two halves are glued together. If I can figure it out if they are sealed I'll be sure to mention it.
Interesting, over here they often have 2 small holes opposite of each other. My guess would be because of safety regulations, hazard of suffocation etc.
Fantastic video and what a what a device! As for suggestions: Ballistic gel would be very interesting as it would offer a nice parallel to many gun channels on YT.
Thanks, it is literally a blast to operate. I have been trying to find a cheap source of mix-it-yourself gel so that I can make a nice big block of it but I really have no idea how much damage a ping pong ball could to.
