Making test tube liquid rockets

this video has been sponsored by Nord VPN you can get 66% off your plan today by going to Nord VPN comm slash Nile red a few months ago I made some super concentrated nitric acid which was close to a hundred percent my main purpose with that video was to explore some of its different properties and of course to also show that it can light common lab gloves on fire so when working with it you either need to use a different type of glove that's chemically resistant or to just wear none at all at the end of the video I did a small demo where I added it to kerosene and I showed how it made it burn a lot better I also briefly mentioned that this mixture of nitric acid and a fuel is commonly used in liquid propelled rockets however at the time I really didn't know much about rockets in general so I didn't go into any real detail after posting that video though I got a lot of comments encouraging me to explore liquid rockets in general a patron of mine was even kind enough to send me a book called ignition by John Clarke I initially planned to just read the book for fun but by the time that I was about halfway through it I knew I had to try out some of it for myself however the book was very clear about how dangerous this could be so I was careful to only choose the reactions that I felt comfortable with when it comes to liquid rockets most of them are based on a by propellant system where a fuel and an oxidizer are reacted together to generate the thrust these are some of the common by propellant mixtures and they generally fall under two main categories hypergolic and non hypergolic the non hypergolic ones need an outside ignition source to get the reaction going but the hypergolic ones reacts so vigorously with each other that they self ignite on contact on a small scale most of the non hypergolic combos require a somewhat complicated set up to fire mixing the fuel and the oxidizer in the right ratio can be really hard and it also requires an outside ignition source I've never seen the done on lab scale and this is what the typical professional set up seems to look like on the other hand for the hypergolic s-- i just need to mix together the two liquids and it can even be done in a test tube periodic videos has already covered this topic a little and this was a cool clip from one of their videos they had this cool setup where they filled two containers with a fuel and an oxidizer and then they let them mix together [Applause] I might try something like this when I get a bit more comfortable with how this all works but for now I'm just gonna be sticking with test tubes an oxidizer that's commonly used his pure nitric acid and I had some on hand from the previous project that I mentioned before for the fuel there were many options but I just went with aniline because again I already had it Adaline was tried early on as a rocket fuel but it was never really used mostly because of its freezing point in its pure form it freezes at negative 6 C which meant that it could only be used in warm climates people tried to mix it with other fuels to lower this freezing point but no one was ever really successful the main fuels that are used now are hydrazine and hydrazine derivatives but hypergolic Lee annalen should give a similar result so as I said before the setup is pretty simple all I needed was a test tube and a small amount of the nitric acid and the aniline I started by adding the nitric acid to the tube and then a drop-wise added the aniline there was a slight popping sound the moment it touched the acid and it made me flinch a bit it never ended up firing but there was clearly a reaction going on that was causing the aniline and the nitric acid to boil I decided to try it again but this time I added a lot more Annalee initially it was just like before and it just cost with the oil but then it suddenly ignited after these two runs I was getting a bit more comfortable with this mixture so I decided to just shoot in a bunch of the aniline all at once the reaction seemed to be quite fast though and I felt that it would start igniting before us even able to add all the aniline to get around this I shot it at the wall of the tube instead of directly into the acid I was honestly a bit nervous to do this but the result was definitely worth it there was also a second firing which was kind of interesting I waited for the tube to cool and for all the gases to go away and then I broke up all the solid stuff I'm not a hundred percent sure what this is but I imagine it's a nice combination of carbon and a bunch of side products I think that most of the Adaline though was converted to gases like steam co2 nitrogen and nitrogen oxides in full-sized rockets this residue can also form and it can cause the combustion chamber to get jammed up I think the amount that was formed here was excessive though because my ratio of aniline to nitric acid was definitely not ideal also a real rocket maintains a much higher temperature which helps burn everything away I decided to try it again with a bit more of the two components and the result was quite similar the initial delay before firing seemed to be a bit smaller but I think this was just because my first run used very little of both chemicals the next thing I wanted to see was how it behaved in a smaller tube this other one was both a lot shorter and thinner the first thing that I noticed was that it seemed to have a smaller ignition delay so on the computer I went through the footage frame by frame to see if this were the case what I found was that on average the smaller tubes took about 12 frames from the moment of contact and the larger ones took about 20 considering that there's a 17 millisecond got between each frame this means that on average the larger tubes took about a hundred and thirty six milliseconds longer to fire I think the reason for this was the initial expansion of gas which caused the liquid in the small tubes to mix a lot more violently I don't know the exact reason for this but I imagine it just came down to space where the larger tube had a lot more of it to accommodate the expanding gas in any case though I think the ultimate effect of this was a more vigorous mixing of the liquids and a faster ignition you listen closely in the larger runs there's a very distinct boiling sound as the vapor builds up followed by a nice pop but in the smaller tubes it seems to happen way faster and all the sounds just get jumbled together and the last thing that I noticed was that when I slowed things down the ignition point for the smaller tubes seemed to be consistently higher than the big ones I think this makes sense with what I found so far and the more vigorous reaction is able to push the gasses further before they ignite however because the smaller tube was so much shorter the ignition happened really close to the end of it after noticing this my friend suggested shortening the tube even more to see what would happen so I got out my dremel and I cut off about a quarter of it the first attempt kind of worked but a lot of the contents were just thrown out of the tube all the streaks of white smoke are from drops of nitric acid falling back down the second try was really interesting and I think it only just barely ignited and when I went frame by frame I was really intrigued by what I saw the fire started way up in the vapor cloud and then it traveled up to like the rest of the vapor and down to the liquid mixture run was the best out of all of them it ignited just barely outside the tube and it gave a really nice sound as well we figured that the length was probably close to the limit but we wanted to see what would happen if it were even shorter so I got out the dremel again and I cut some tubes in half the first run was a total failure and everything was just thrown from the tube you can even see some aniline and nitric acid splattered on the back wall the next one was also a failure and it was again just a puff of smoke for the last one though I tried adding a lot less aniline and I actually got it to ignite from these tests I couldn't really conclude very much but tube length was obviously affecting ignition I think the major reason was all the splashing that I mentioned earlier and when the tube was too short it just ejected everything before he got to the ignition point because I knew that the larger tubes didn't splash as much I figured that at the same length they should still be able to fire so I cut them down and tried it a few times and every time I was consistently able to get it to ignite I also didn't need to use Lausanne allene and I just blasted it in like I normally would after doing all of this I was starting to get a feel for how this reaction behaved and I felt comfortable trying one last thing this is a photo of what a typical rocket engine looks like on the inside notice how the combustion chamber is more or less cylindrical just like the test tubes however it then quickly gets more narrow before opening up to the nozzle the general name for this is a convergent divergent nozzle or a de Laval nozzle I don't want to get much into the physics of it but the overall idea is that it converts the thermal energy of the expanding gases into kinetic energy the gas is forced through this thinner area called the throat which greatly increases its velocity in most cases the gas before the throat is moving at subsonic speeds but afterwards it can be going as fast as 10 times the speed of sound after the throat the gas expands and as it does so it pushes on the nozzle there's also a strong pushing force at the back of the combustion chamber and together this is what makes the rocket move I wanted to see if I could kind of mimic this with a test tube but of course I was a little bit hesitant because I didn't want it to explode i heated them using a torch and then I stretched them out to try to mimic the throat the larger tubes were a lot thicker so it was more comfortable starting with them for the first run I used the one with the least narrow neck [Music] the result was almost the same as the UH narrowed tube but it gave me the confidence to push it a bit further the biggest difference for this one was definitely the initial pop that it made I don't think the microphone was able to pick it up very well but it was significantly louder I did a couple more runs of this to build my courage and then I moved on to the smaller ones the glass in the smaller tubes were a lot thinner and there also wasn't nearly as much space to accommodate the gas expansion this meant that not only were they weaker they'd probably have to withstand a higher pressure which meant they might break just like before I built it up slowly and I started with one that was only narrowed a bit then I nervously tried a much thinner one and it was a complete failure not only they spray the back wall with aniline but it never fired however I still thought that it kind of ended up being interesting I decided to try it again and for the next two runs it still didn't fire the reason for this seem to be similar to before where it was splashing we too much and stuff was getting injected from the top from my earlier test with the shorter tube I saw that adding less and allene could still get it to fire so I decided to try that here I also shot it more directly into the side of the tube so that it wouldn't just be blasted into the acid this time it actually worked and the tube also didn't explode so I decided to try it three more times with a thinner throat [Music] [Music] anyway for me this project was just an introduction to the whole world of liquid propelled rockets I definitely plan to explore more rocketry in general and I think for the next one I'll look into some of the other hypergolic oxidizers and fuels however I'm not exactly sure when I'll be able to do that because I've been having a lot of trouble getting my hands on the hydrazine based fuels in the end I'll make them if I have to but if any of you guys know a source that I can get it from please send me an email over the years I've heard a lot of horror stories about people losing passwords or banking and credit card info because they've done something as simple as checking emails or social media while on public Wi-Fi so before I go I just want to give a quick shout out to the sponsor of this video Nord VPN Nord VPNs are really easy to use service that helps keep your information safe when you're on the Internet even when you're in trustworthy places like hotels you can have sketchy people trying to sniff out your info this was an issue that I always had at the back of my mind but it especially became anxiety inducing once I started this YouTube channel so to me the most important feature is that Nord VPN encrypts and anonymizes all of the data before sending it out this means that even if someone did intercept my data it would mean nothing to them it works on phones tablets and computers and it supports both iOS and Android I personally use it the most on my phone and it's really easy once the app is started I just need to click this one button wait for it to connect and I'm done so with that being said if you're interested in keeping your info safe online you should definitely sign up for Nord VPN they're offering all my viewers 66% off two year plans which you can get by going to Nord VPN comm slash Nile red or by just using the code Nile red as usual a big things goes out to all my supporters on patreon everyone who supports me can see my videos at least 24 hours before I post them to YouTube also everyone on patreon can directly message me and if you support me with $5 or more you'll get your name at the end like you see here [Music]

Channel: NileRed

Views: 2,203,464

Keywords: nile, red, science, chemistry, rockets, liquid, rocket, hypergolic, aniline, nitric acid, vpn, surfing, net neutrality, online privacy, consumer vpn, nilered

Id: OszX18NLtrY

Length: 18min 16sec (1096 seconds)

Published: Thu Oct 04 2018