SCREAMING Shotgun Slug - Rocket Nozzle Experiment

you're watching tough lady maths this video is made possible by generous support on patreon by our viewers rather than sponsorships by videogames mattresses and boxes or other stuff that you just don't want to see today we have a very interesting experiment involving the de Laval nozzle also known as the converging diverging nozzle sometimes called the CD nozzle the brainstorm and creator of this idea is sour towel from Israel now SAR is a candy maker by trade makes delicious candy but he also has a very creative mind and he's very talented for the tests he created seven of these de Laval nozzles and there were quite a few challenges that we had to overcome to make this test possible and I'll explain that in a few minutes invented in 1888 by a Swedish inventor Gustav de laval these nozzles were originally designed to direct high-pressure steam to drive steam turbines or turbines if you prefer but rocket scientists including Robert Goddard utilized the de Laval principle to convert high pressure low velocity gasses into a concentrated low-pressure but high velocity stream of gases coming out the nozzle but what will happen if we drive just the nozzle at a high velocity through the air will it create some sort of ramjet effect to actually increase the velocity well pretty unlikely that just is counter to what we know about physics but will it enhance the stability in any way or possibly just cause it to tumble through the air that's what we really want to find out now if we try to launch these at too high of a velocity that's not going to work because we have a shock wave forming at the nose called the bow shock and that would prevent any airflow from going through the nozzle at all so the first challenge is to keep these at a subsonic velocity next we need some kind of visual indicator to let us know when we have potential airflow through the nozzle now this is done with a very light weight paper plug that will just fall out if it's flying at a supersonic speed the plug will not fall out we'll also use some lightweight oil and some red dye which we may be able to see with the high-speed camera i've jabbered on long enough let's get out to the test range and see how these things fly we're up fifteen yards okay charge up the steam reservoir flux capacitors vacuum pump saw vacuum pump on our vacuum gun okay I am ready holy mackerel 891 FPS [Applause] even though we were well below the speed of sound Mach 1 the paper indicator plug remained inside the nozzle now this is a surprise to me because I thought if it's below the speed of sound there's no way the plug is gonna remain in there I've never seen a test like this done before so chances are you haven't either we managed to capture that one you'll see in the video how far that thing flew yeah and this is how I found it out there in the week yeah I mean sinner on there I didn't have you know I didn't give these things much chance of being accurately holed up together all the way ya know there's some plastic stuck in the back and bit of TP right there oh yeah the little plug there shouldn't have been it should have ejected it out but that one is still good perfect Danny is charging up the trebuchet ok the first one was very accurate let's see if that continues I'm ready Wow now in this shot we've reduced the velocity a little bit and sure enough our paper plug has fallen out the back now we do have the potential for air flow at this point but we're not seeing any indicator visually which would be the oil that's on the nozzle that would be atomizing as it's flying through the air even though this isn't flying at a supersonic speed it's still in that transonic range between Mach 0.72 and Mach 1 we won't have to reduce the velocity very much to bring it down to true subsonic velocities on a positive note at least the nozzles are stable in flight and they're relatively accurate to remarkably we were able to recover six out of seven projectiles in the test five of them were still in perfect condition after recovery okay let's see what does to a roll of wet toilet paper just because because we go ring out the shawarma new yeah okay adjust the pressure ruptured disks charge up the steam pressure on the steam catapult I'm ready we find that while I'll be surprised even though we got an error reading on the chronograph on this one it would be safe to say that the velocity of this one is probably a bit higher than even the first one not only do we have the paper plug still in place but we also have part of the gas seal component still lodged in the back of the nozzle I believe if we had allowed the nozzle to continue traveling downrange further allowing it to decelerate more all those components would eventually just fallen out the back Kevlar vest caught it huh cut that little bugger it had the back pushed out about three inches here wow that didn't think we had it to begin with bit but this is interesting because the paper mache little paper plug there it's well unless that's from the toilet paper it's either the toilet paper or some of this fiber out of the vid it's definitely paper okay but we'll have to see on the high-speed that's three out of three that's pretty good for capturing something like that that was a lot of energy for something that's sub subsonic yeah not bad at all all right okay let's play 25 yards that's usually closer than that okay I'm ready here we go just stuck right in it there's no results they little a toilet paper why'd you put in there to see if there was air flow through this row it all the way to here I saw a green part of the you know the Launch System the wad yeah I think it's been cutting discs out of that yeah and then it kicked out the little toilet paper wad when the lid tried to come back up through the hole okay it's a firmly embedded in there there's no air flow through that no air flow okay that's that shockwave in front well we're still subsonic though well there's still going to be a little bit of a wave in front right yeah we pushing a weak shock wave yeah it's pushing here yeah but again even at subsonic speeds it's it's not there's not a pressure to push it out no flew yeah you have an oil dupper never it's died up okay ready to run a ruptured disk in our vacuum cannon okay I'm ready all right here we go way to do it the best running away well I got smart huh as our outside air temperature increase throughout the testing so did our velocities we didn't compensate for that properly we were trying to reduce the velocity as we progress along but as you can see that was a little difficult to control so we're still in that kind of weird world of the transonic velocities so we'll reduce the velocity even more and get it into the true subsonic velocities and see what effect that has a tribute to Hickok or somebody I don't know a lot smaller target than what Hickok shoots at though yeah well we didn't bring any pots to smoke okay we got a little red dye on this one with some oil maybe we'll see a vapor cloud maybe okay I'm ready when you are in this test I was expecting to see visual clues indicating when we had airflow going through the nozzle so instead of visual clues we had audio clues which I didn't expect to you know I didn't expect these things that kind of whistled through the air like they did kind of a high pitch once we were able to get out of that weird transonic range and into true subsonic speeds that's when the magic kind of happens and we're actually getting that airflow like you would expect it to occur I expected it to occur at a little higher velocity than this though those things are pretty good about punching circles oh yeah like wad-cutters is the soda can getting those projectiles in perfect shape without 25 yards let's try out let's see if we could see anything different at 25 yards that vest took off like a scared rabbit I did too the first whistling nozzle phenomenon was not a fluke at all and we were able to repeat the results a second time even though we had the paper plug falling out of the back which would indicate a potential for air flow we never saw the visual clue of the oil or the red dye atomizing through the nozzle and out the back unfortunately but luckily luckily we had the audio clue of the whistling indicating we had flowed through the nozzle I hope that you also learned something from this video I sure did thank you for your support on patreon and channel membership

Channel: TAOFLEDERMAUS

Views: 505,677

Keywords: rocket nozzle, de laval, physics, rocketry, science, education, nature, experimentation, slow motion

Id: U0x85dNOwuM

Length: 13min 2sec (782 seconds)

Published: Mon May 06 2019