If you're interested in looking at other oxidizers, I can pass along some tips on N2O from the research I'm involved in. Our motors are on a bit larger scale, but liquid N2O is relatively safe if you follow a few main safety guidelines.
Oh boy that brings back memories! When I was still in highschool, I had made my own oxygen generator setup with an empty wine bottle, some hydrogen peroxide, hydrochloric acid and a rusty nail. I promptly decided to have fun with it, and start burning coal in a flow of pure oxygen. Which was quite fun until the vinyl pipe I was using touched the charcoal, and did exactly what you show at 7:17 : I had inadvertently built my first hybrid rocket! Watching the pipe wiggle on the ground as the flame front was progressing inside it, I stomped it to stop the flow of oxygen. The other end of the pipe promptly popped off the wine bottle with a small hydrogen peroxide geyser, and the combustion stopped. I then decided I would try again, this time adding a steel pipe at the end of the vinyl tube. That's how I inadvertently built my first thermal lance. After using the same pipe-stomping technique to extinguish it, I moved on to copper, which has a lower melting point, but is not flammable, even in pure oxygen. I had quite some fun by filling a hole in a brick with a mix of charcoal and small aluminium pieces, then adding a charcoal ember to it, and lowering that long copper pipe in the hole with pure oxygen coming out of it. It made a beautiful white light, with a weird flame on top, green on the inside and blue on the outside (I assume that's due to the copper from the pipe). It was giving off so much heat, I could lower the copper pipe without feeling any resistance, as it must have instantly melted in contact with the burning charcoal and aluminium. I've still kept the bits of molten metal from back then!
Hi, I'm actually a researcher working with HREs, currently writing my thesis on HRE scaling and the effects on performance in going larger while keeping scale. Our rocket is simulated using a combustion model my supervisor made (he's pretty brilliant, but very quiet hahaha). Our simulation model is HTPB and N2O however so far it agrees well with empirical models. Current issues are the regression rate ("burn" rate) of the fuel and stoichiometric length in design. Cantwell gave a good presentation on current developments, and a HRE with a single port giving comparable Isp to larger rockets is doable using GOX and highly refined (basically) candle wax with aluminum particles (I think it was 20% by weight?) below 10 micrometers. Anyways, if you get a big candle from Ikea, stick it in a metal pipe, drill a port into it, and run some oxygen through it, you can get a pretty good rocket out of it :p. Also, you need a proper converging diverging nozzle that needs to choke (at least above double atmospheric pressure if we're being conservative); that can be done, you need a 3D printer with machinable wax and you can make a decent casting with that. I should probably try all of this...but I need to write and i'm procrastinating right now >_>. Happy to answer any questions! EDIT: also, I can hear buzzing on your rocket, means the combustion is very unstable. This is a problem with HREs but can be greatly mitigated with a pre and post combustion chamber. Also to fly, you really do need a proper nozzle.
As a general rule, solid hybrid fuel should be quite opaque. If the fuel is translucent, infrared will heat all the fuel rather than only that directly in contact with flame. Wax is problematic, except for very short tests. One might do well to use HTPB with .5% carbon black at first, as adding metal powder makes matters a bit more challenging.
+nabil iben-sobih the go-to material for nozzles is graphite. Throat temperatures are quite high, and graphite will resist it if anything will - won't melt or spall, and are usually reusable after a simple cleaning. You can get fancier with larger nozzles with graphite liner and lesser materials for the bell/bulk of the nozzle. While graphite is somewhat expensive, you can go to "nozzle plates" (multi-venturi), where the graphite is a relatively thin circular plate with multiple small nozzles bored through. Weight and cost savings of as much as 10:1 can be achieved this way, venturi profile is less critical,/faster and performance loss over a single nozzle is usually minimal. Full size single nozzles need lathe machining, preferably CNC. Nozzle plates can be done with a drill press, and quite minimal manual lathe work. Most commercially made amateur high power solid and hybrid motors use graphite.
How do you get into the field of research like this ? I'm not gonna pretend like I am a expert or understand all the science behind rockets and space craft.
@@jillvalentinefan77 Are you referring to me? I simply got interested in rocketry beyond model rockets, read the relevant books, happened to have a number of friends also very deeply into the hobby. One of them designed, built, flew and sold (to others in high power rocketry hobby) "solid core" and hybrid motors into the 2000+ pound thrust range. Another was experimenting with tri-fuel/hybrid motors. We all wanted to build various designs of our own, and a local highschool had us show up for every machine shop adult course every summer for several years. We used to joke with the teacher that he must have failed miserably in teaching us, because we had to keep coming back. The whole point was to get access to decent machine tools. Part of what happened is that we all ended up making parts for each other's motors. It was our interest, so we had to understand *what* the part was for, and how it was designed. So we taught each other what we had learned in our various inherent specialties. I've made graphite nozzles both of the single venturi and "plate" varieties, for combustion chambers up to 8" in diameter. I've built combustion chambers for solids and hybrids, pre-heat shrouds for tribrids, interstage modules, electronics subsystems etc. Assisted in the manufacture of several kinds of rocket fuel, etc. Test engine fires, ground support, Launch Control Officer and so on. I wasn't quite bitten with the same level rocket-bug as the others, so my projects weren't quite as adventurous as theirs were, but I ended up understanding just about as much as they did. They pushed the envelope more than I did, and as a result had more failures than I, but, that was okay by them too. One of the things you learn in life is that people who do things they enjoy (which is what a hobby is), can often understand things far more deeply than those just drawing a pay cheque. It's not work, it's play. Even better if you can get paid to do something you'd happily do as an unpaid hobby. The best way to learn about basic rocketry is to get bitten by the high power rocketry bug. You can fly Estes rockets without learning a thing, but to successfully fly level 3 high power (my level of certification), you *have* to learn quite a lot, no choice. If you want to start, if you're very lucky, you'll have a high power rocketry group in your area and go to their launches, ask questions, and get yourself started. If there's no high-power group, look around for more serious model rocketry groups. They'll usually have a high power afficionado somewhere looking for some company.
The sausage triangle is a very good fuel. The oxidant may be N2O. The video is more about regulatability through pure oxygen, which is a good concept, but in reality it is necessary to first heat the fuel and it takes some time. Repeated ignition also requires several ignition attempts. Hydrazine engines can ignite themselves with a platinum grille even under vacuum. It is therefore very fast, safe and reliable. Therefore, it was used in the Apollo lunar return module.
Hey thanks for watching! I'd like to hear from you what you think of this more casual style of video compared to what I've mostly done in the past where everything is strictly scripted and overdubbed. Had this video been made in the way that I am used to it would have likely been much shorter and concise, but also contained much less information. I intend for most of my project tutorial videos to still be made in the same way they always have but this new format is something I've been playing with for my last 2-3 videos to see how well it's liked. Thanks to my Patreon supporters once again! Take a look at my page here and consider supporting my videos if you enjoy them: www.patreon.com/NightHawkProjects
This is amazing, thanks for sharing! I'm not a scientist, but I'm fairly certain the visual effect of the rocket core shrinking is caused by its IOR (index of refraction) decreasing as the temperature increases. As the temperature of the acrylic increases, its permittivity (also called dielectric constant) decreases, therefore so too does its index of refraction. The image seen through the transparent surface is becoming less refracted.
I decided to use your idea of this engine. I decided to make it a jet engine, with an after burner. Took a lot of time but I did it, a fully Manual throttle lever. I also made a auto starting sequence, I loved remaking your project and making a jet engine out of it. It uses jet fuel that I bought, really loud and produces a pretty good amount of force.
I would love to know if you measured the thrust of your rocket engine. I'd like to see how it varies with the "throttle". I also believe with a throttled engine like this you can never have an ideal DeLaval nozzle shape across the throttle range. The nozzle shape will only be good for a certain thrust and not another. You would probably maximize the nozzle for full throttle operation in a practical application. Anyhow, I like the style of video. I really like the detailed science explanation. I also love this subject matter. I would love to see if you can make a liquid rocket engine, Cody from CodysLab was working on one a while ago but has not done any videos about it recently.
I have not measured the thrust. Building a device to do so might be a future video if this one does well. I agree that there's no such thing as the perfect nozzle for a rocket with variable thrust, unless the nozzle is also variable. Mine was pretty bad though for any range. I'll make a better one if i try again.
NightHawkInLight I've built a simple low cost electronic thrust measurement system. I have the build and everything on video, I just have not edited the video for upload to my channel. If you do one, I'd be happy to help.
I loved how detailed the video was, I do enjoy you explaining things in a quick and easy understood fashion. The information is compressed in a way I can listen, and it's pretty hard for me to concentrate on things. Keep the good work.
Heating is a very known method to restore car lens, CD surface restore, etc. The shrinking effect it´s because heat produces a polymer chain re-arranging as the material goes to a fluid state. Very nice video!
The core flame is melting the machining marks that make it look opaque, and keeps it in a liquid state once burning, so you can see right through instead of seeing the light deflected off the rough machining marks.Much like you'd do by spraying water on a frosted glass with a cold liquid inside. It looks like it's shrinking because the necessary temperature to make the acrylic melt and burn with the oxygen, was acquired from the tip backwards because the ignition source is at the tip. As the interior started burning with the oxygen, it traveled back until it reached the source of the oxydizer. That good enough?
Hey NightHawkInLight, a quick critique/suggestion on your nozzle. if you look at the video, the exhaust isn't attached to the wall of the nozzle. This is flow separation, it happens when the pressure of the gasses in your exhaust are too far below atmospheric pressure, and the atmosphere forces it's way into the nozzle and pinches down on the exhaust giving you that little jet coming through. It's a pretty easy fix though through trail and error, just slowly shrink the outlet diameter until it sticks back to the nozzle wall. Also I'd shrink the center hole to about 7/8 of what it is now. edit: looking at it again, it actually seems like the pressure inside the acrylic tube is too low, so maybe an easier fix would be shrinking the diameter of the center hole to increase the pressure.
Regarding the apparent shrinking of the hole, here's my take. For a start, the hole appears bigger than it actually is because the surrounding cylindrical piece of acrylic is acting like a magnifying lens. At room temperature, the refractive index is about 1.47. As the layer of acrylic near the burning center heats up, the refractive index drops (in most plastics, the index goes down as the temperature goes up). The magnifying effect is then reduced, which makes the hole appear to shrink. Hope that makes sense!
Nice! I was comment searching for an answer. My best ideas had been uneven thermal expansion due to an uneven heat distribution, but the apparent change seemed to quick for that. One other idea I had tumbling around was that maybe a fusing of all the scratches and cracks from drilling allowed the clarity to extend further in.
My take home from this was anything that can burn can be moderated in the presence of varying degrees of oxygen, I wondered how the plastic rocket fuelled engines work. Thankyou
Is anyone else on here really annoyed when movies/TV use oxygen tanks as an explosive, because they say pure oxygen is an explosive? I love how you show how bogus that notion is!
An enclosed container of any gas under high pressure can be 'explosive' if heated high enough. Even water heated in an enclosed tank would be...even a water rocket tank will mechanically 'explode' if the pressure was high enough.
USWaterRockets I think what you mean is the big fireball you see in the movies, and yes it is extremely annoying. Only flammable compressed fuel can create a fireball
Damn, I've been subscribed for years and never spotted this video - just what we need in the UK where hybrid rocket engines are the only ones you can really build legally.
Make a graphite holder to encase the entire thing along with a couple of graphite/steel screws to hold the nozzle and the holder together. Make a bunch of those acrylic "fuel rods" but drill a hole at the side for a fire to be lit through an ignition coil. make 4 of those and attach it to a go cart with some excellent rudders/steering mechanism. I would love to see that, great job man! Also make it such that the acrylic fuel rods can be replaced easily so the go=cart can be re-used. If you wanna use this for an aerial vehicle you'd have to develop a very efficient way for refuelling XD
+James Di I think he was referring to why the burn regression rate at the forward end of the chamber was slower than at the back (nozzle) end. This is largely because the velocity of O2 is higher at the head end, and the OS s focussed more to a fine jet. As the O2 jet flows towards the back, it's slowing down a bit, expanding, and hotter (preheated). Which causes the acrylic to burn, and hence regress, faster. You can see a somewhat analogous effect visually at the nozzle itself, where the flame is not expanding to match the really coarse pseudo-taper he drilled. This is "classic" underexpansion of the exhaust. In more serious rocket design, not only does the nozzle venturi have to be precisely shaped to produce optimal thrust, you'd also shape the gas injectors to try to better balance the regression rates. Machining precise curves in nozzle venturi is quite hard if all you have is a manual lathe, rather than full CNC. In larger amateur hybrid motors they often "cheat", and instead of a single venturi, in a big fat chunk of graphite, the nozzle is often a much thinner graphite plate with numerous smaller venturi . This has two advantages. The shape of each venturi is less critical, and it's a much smaller chunk of graphite - cheaper and a lot lighter. As a side note, while Nitrous oxide is rather more difficult to obtain than O2, and isn't quite as energetic as O2, it is FAR SAFER than O2 in large part because it's not so aggressive. Secondly, since N2O is quite easily to liquify at room temperature, the oxidizer tank in an amateur hybrid doesn't need to withstand as much pressure as a O2 cylinder. It's effectively impossible to have liquid O2 at room temperature (it's vaporizing off at a horrendous rate) no matter what pressure you have it at, and for gas, you need much higher pressures to have nearly the same oxidizer capacity - MUCH heavier tankage. Further, by careful calculation you can pick the ideal injector size, so simple Nitrous liquid -> gas evaporation provides the pressure you need to run the rocket combustion cycle, and the pressure remains relatively constant until the nitrous runs out. Flying amateur rockets with liquid O2 is impractical (not to mention quite dangerous), very difficult to obtain, and if you use gaseous O2 in the tank, the delivery pressure varies wildly, and the thrust is no where close to being consistent. With O2, you generally have to use liquid O2 and pumps to get consistent thrust. O2 is ideal for demonstrations like this, where the overall visualization is more important than optimal thrust. But if you want to do high power rocketry with reliable and consistent thrust, DO NOT use O2, use nitrous. Leave O2 to the big boys with big bucks..
Not only will a poorly designed nozzle not produce optimum thrust, it might not even generate significant amounts of thrust at all. The nozzle throat needs to accelerate the gas to sonic, then expand it supersonically. In order to get sonic flow in the nozzle, you have to have at least 30-40 psi chamber pressure, which it looks like you didn't have since the nozzle was just press fit over the chamber. Thrust is linearly related to exhaust velocity, so if you aren't getting at least sonic flow, don't expect more than a pound of thrust at most.
It's a conceptual model, not a functional model, meant to be built by people at home. Will it launch a payload? No, it wont. Will it teach a child, or function for a demonstration of, how a rocket engine combusts, while making a fairly impressive visualization? Yes, it will. I'm pretty sure he knows the has little to no thrust, but it DOES explain the concept of hybrid rocket engines.
Thrust is not related to exhaust velocity, specific impulse is. Thrust has many variables, e.g. nozzle size, shape, expansion ratio, type of propellant, pressure in combustion chamber etc.
KersZZ Thrust is absolutely related to exhaust velocity. The thrust equation is T= mdot*v_exhaust +A_exit(P_e-P_a). And for an optimized nozzle with Pa=Pe the only participant in the thrust equation is massflow times exhaust velocity. Isp (specific impulse) is simply exhaust velocity divided by 9.81 (g).
Very impressive! I'm a student at a Swedish university and currently working on somewhat similar hybrid-rocket-related projects for both my masters thesis and in a separate student project. To answer your question about what happens at 8:28, I believe this is the fuel grain forming a fuel vapour zone, with heated and vapourized fuel flowing inwards into the oxidizer stream where it is ignited. Because it is not hot enough to glow, it gives the impression of the fuel grain 'shrinking' but if one looks carefully, one can faintly see the 'real' edge of the solid fuel grain which is regressing outwards. For an illustration of this, see page 589 (figure 15-7) of G.P. Sutton's Rocket Propulsion Elements, 7th ed.
No. Because air is only 20% oxygen the other 80% will cool off the fuel as it blows past faster than the oxygen can feed the flame and the rocket will go out.
Amazing ... I thought I was going to be bored out of my wits, but I really learned something today. The charcoal and oxidizer mixture caught my attention. Good job explaining how all this works.
@Pen is the funny thing is you dont have to search for any dangerous and in some countries illegal stuff because youtube rubs these videos under your nose until you watch them to get rid of the youtube suggestion xD
Totally awesome video, we used to mess around with that stuff in high school! Acrylic tubes Bring back memories for me. When you drilled that tube It brought back memories from high school, because when you would grind on acrylics, there is a certain smell comes from manipulating the acrylic ! Awesome video 10 thumbs up by Roger Ebert
Good job, great view of the inside. Don't worry about the nozzle being perfect on a "proof of concept" motor. Going bigger than optimum keeps the thrust down and gives a longer burn time, both desirable when you just want to burn it and see how it does. I'm not sure exactly how they determine nozzle size on a hybrid, but on a solid motor, it's some serious math. On a hybrid, you do have another advantage in that chamber pressure is limited by the oxidizer pressure so if your nozzle is too small, you just need to use a oxidizer pressure within the working limits of the motor casing and it won't overpressure as it would if it were a solid propellant. (chamber pressure at or above oxidizer pressure will cut off the combustion)
Indeed, probably potassium nitrate. Potassium nitrate + sulfur + charcoal is black powder, the propellant most often used in fireworks. In amateur rocketry is it also popular to use sugar as a fuel (rocket candy), again with potassium nitrate as oxidiser.
Big or small, metal, generally powdered spherical aluminum, is the fuel and needs a binder like HTPB or PBAN to hold the powdered oxidizer, and the metal together. The binder also burns in the process as a fuel.
Toast the oxidizer is most likely potassium nitrate because it is very easy to get. you can get it in some tree stump remover if you get the right brand.
Since you like Wiki, here is also an excerpt on Space Shuttle Solid Rocket Booster or as you said "...the very stuff NASA boosters use": 'The rocket propellant mixture in each solid rocket motor consisted of ammonium perchlorate (oxidizer, 69.8% by weight), atomized aluminium powder (fuel, 16%), iron oxide (catalyst, 0.2%), PBAN (binder, also acts as fuel, 12%), and an epoxy curing agent (2%).[7][8] This propellant is commonly referred to as Ammonium Perchlorate Composite Propellant, or simply APCP. This mixture gave the solid rocket motors a specific impulse of 242 seconds (2.37 km/s) at sea level or 268 seconds (2.63 km/s) in a vacuum. The main fuel, aluminum, was used because it has a reasonable specific energy density of about 31.0 MJ/kg, but a high volumetric energy density, and is difficult to ignite accidentally. The propellant had an 11-point star-shaped perforation in the forward motor segment and a double-truncated-cone perforation in each of the aft segments and aft closure. This configuration provided high thrust at ignition and then reduced the thrust by approximately a third 50 seconds after lift-off to avoid overstressing the vehicle during maximum dynamic pressure (Max Q)"
And directly from an academic source can be found this excerpt from Sutton's 'ROCKET PROPULSION ELEMENTS' 7th edition on pages 475-476: "3. Composite propellants form a heterogenous propellant grain with the oxidizer crystals and a powdered fuel (usually aluminum) held together in a matrix of synthetic rubber (or plastic) binder, such as polybutadiene (HTPB)*. Composite propellants are cast from a mix of solid (AP crystals, Al powder)* and liquid (HTPB, PPG)* ingrediants. The propellant is hardened by crosslinking or curing the liquid binder polymer with a small amount of curing agent, and curing it in an oven, where it becomes hard and solid. In the past three decades the composite propellants have been the most commonly used class. They can be further subdivided: (1) Conventional composite propellants usually contain between 60 and 72% ammonium perchlorate (AP) as crystalline oxidizer, up to 22%aluminum powder (Al) as a metal fuel, and 8 to 16% of elastomeric binder (organic polymer) including its plasticizer." (2)-(5) talk about other formulations that can include RDX, nitroglycerine, etc for higher energy ( Isp ). You can reduce or even eliminate aluminum from APCP but at greatly reduced performance relying only on the binder as fuel.
If I had to guess, either the acrylic itself is expanding from the heat, or the opaque layer of acrylic leftover from friction with the drill is being melted and returned to a more transparent configuration. As the point of combustion moves backwards, the source of heat moves backwards and thus the effect. lensing from the case itself is probably exaggerating the size of the layer so it looks like the core is dramatically shrinking/opaque layer is very thick when its probably only a small amount. I could figure it out with two minutes of hands-on testing, but that's my best guess for you from looking at it here.
enjoyed the video. Small point however - the oxidizer just needs to grab an electron with great force ( very simply put). it does not need to release oxygen but it does what oxygen does in a Redox reaction.
xWood4000 socialism ;) what's good for one is good for all, what's bad for one is bad for all. Risk of injury, risk of death, risk of weaponization. Banned.
I didn't have a setup available to measure it. Due to the inefficient nozzle probably only around 5lbs. Acrylic isn't an ideal fuel in any case, it just makes a good demonstration because it's clear. Using a good nozzle, proper fuel, and an oxygen valve that can dump oxidizer quickly you might be able to get in the range of 50lbs of thrust out of the same size rocket.
That is a very good, educational video! However, aren't you a bit concerned about wearing gloves when holding something under a drillpress? It was strikty forbidden in our metalshop to do so.
I know this is a year late, but the pulsing effect is likely due to shocks. When a nozzle is not ideal, shocks form inside. When a shock forms there is a pressure difference from one side of the shock to the other. This pressure difference causes the shock to move, because the conditions by which the shock formed are not the same. The shock eventually exits the nozzle and a new one forms. This is likely what is causing what you are detecting as the pulse.
I really appreciate Will Wheaton for doing this video. It just shows that he's more than just a pretty face who appeared on Star Trek once or twice. ;-)
Try using N2O cartridges for a better oxidizer. It will also keep the weight and size down since they are about the same size as CO2 cartridges. This will help you if you want to get airborne hybrid rockets.
The core looks the way it does because you are basically flame polishing a tube. With acrylics you can turn a matte edge completely clear with a quick burst of high heat run along the edge. So whats happening here isn't that it's catching fire but the heat builds up to the working temp for it to polish and smooth off. So rough and opaque to smooth and transparent! ;D
8:29 I think it changes from cloudy to clear because the drilling cause scratch marks on the inside. But when the engine turns on, the scratches have a high surface area and burn away quickly.
thanks for making such nice educational videos..I actually learnt a lot of stuff about the thrust of rocket ..and such channels should really grow if science lovers exists..😃
the acrylic burns on the inside or appears to be boring due to something i remember as flame polishing. Im not 100% sure if thats what it is but usually when making acrylic fish tanks we use a torch and burn it to make it appear clear in areas that are not visible. such as when we sand the side or like how you drilled through it. I do believe thats why the acrylic appears to be burning
I think the shrinking of the inside is due to diffraction. When you drill it it leaves a rough finish which just diffuses the light but when it is melted it gives a clear smooth finish and as it is a curve it diffracts the light more.
Nice work. You could try to make a mechanism that holds the flap cap onto the barrel. It might be too slow because starting the moment the projectile is released, the flap could start leaking air. if you manage to only open at high pressure, the flap can make optimal use of the energy to open quickly as all the air to push it open is still in the tube. This, just like the alu cap will cost energy as the projectile will hit a compressed air bed just before it comes out. But is will give you faster reloading. Add a small magnet on the plunger and the projectile this way you can make the diameter of the projectile bigger so that you have less air leakage during the forward movement of the projectile. The fact that you could add tape tells the projectile is not snug enough in the tube.
It looks like it shrinks because the cut you made in the middle roughened the surface of the inside of the acrylic tube making it less see-through. When you started burning it it burned away that rough layer and made it see through like the rest of the tube.
How many of those 2-ounce oxygen tanks did you go through during this project? They go so quick.
For this one? Only two. For my thermic lance project, like 10.
NightHawkInLight wow 2 amazing youtubers who grown my actually knowledge i love you guys !!
Cody'sLab I love both your channels. you have both have been a great inspiration to me.
If you're interested in looking at other oxidizers, I can pass along some tips on N2O from the research I'm involved in. Our motors are on a bit larger scale, but liquid N2O is relatively safe if you follow a few main safety guidelines.
Can you come up with a way to measure the thrust? I would love to know how much thrust this is generating.
Oh boy that brings back memories!
When I was still in highschool, I had made my own oxygen generator setup with an empty wine bottle, some hydrogen peroxide, hydrochloric acid and a rusty nail.
I promptly decided to have fun with it, and start burning coal in a flow of pure oxygen. Which was quite fun until the vinyl pipe I was using touched the charcoal, and did exactly what you show at 7:17 : I had inadvertently built my first hybrid rocket!
Watching the pipe wiggle on the ground as the flame front was progressing inside it, I stomped it to stop the flow of oxygen. The other end of the pipe promptly popped off the wine bottle with a small hydrogen peroxide geyser, and the combustion stopped.
I then decided I would try again, this time adding a steel pipe at the end of the vinyl tube. That's how I inadvertently built my first thermal lance.
After using the same pipe-stomping technique to extinguish it, I moved on to copper, which has a lower melting point, but is not flammable, even in pure oxygen.
I had quite some fun by filling a hole in a brick with a mix of charcoal and small aluminium pieces, then adding a charcoal ember to it, and lowering that long copper pipe in the hole with pure oxygen coming out of it. It made a beautiful white light, with a weird flame on top, green on the inside and blue on the outside (I assume that's due to the copper from the pipe).
It was giving off so much heat, I could lower the copper pipe without feeling any resistance, as it must have instantly melted in contact with the burning charcoal and aluminium.
I've still kept the bits of molten metal from back then!
So you had enough hydrogen peroxide to create enough oxygen to make a thermal lance?
Caju sounds like the DHS might not like you
Ok
Wow that’s so cool ✨✨✨
That very first start up at 8:00 is really impressive to say the least! Thanks for sharing!
johnnyq90 fancy seeing you here
It was lit.
johnnyq90 I love your videos!
Dude can u try to do it yourself?
Oh hi!
your eyebrows make you look sincere
when has guys get their eyebrows done, smh
Hansolo lol
Hansolo but his beard is asymmetrical so I don't trust him
Yeah I see Ted Cruz too.
casey b Ted Cruz got them creepy jowls that make him look like he's wearing a mask like in point break
Excellent video. Felt very educational.
Grant Thompson - "The King of Random" yes it did
Grant Thompson - "The King of Random" night talk and you should do a colab! it will be crazy what you guys can come up with!
Omg I have seen u and Cody I'm subbed to both of u
Grant!!!
Cody AND you? This is amazing!
Sweet! Thanks so much for the link!
Hey
A man has fallen into the river
@@WhiteBuzzardP in lego river in lego si-ver. Start the new rescopter!
Hi, I'm actually a researcher working with HREs, currently writing my thesis on HRE scaling and the effects on performance in going larger while keeping scale.
Our rocket is simulated using a combustion model my supervisor made (he's pretty brilliant, but very quiet hahaha). Our simulation model is HTPB and N2O however so far it agrees well with empirical models. Current issues are the regression rate ("burn" rate) of the fuel and stoichiometric length in design.
Cantwell gave a good presentation on current developments, and a HRE with a single port giving comparable Isp to larger rockets is doable using GOX and highly refined (basically) candle wax with aluminum particles (I think it was 20% by weight?) below 10 micrometers.
Anyways, if you get a big candle from Ikea, stick it in a metal pipe, drill a port into it, and run some oxygen through it, you can get a pretty good rocket out of it :p. Also, you need a proper converging diverging nozzle that needs to choke (at least above double atmospheric pressure if we're being conservative); that can be done, you need a 3D printer with machinable wax and you can make a decent casting with that.
I should probably try all of this...but I need to write and i'm procrastinating right now >_>. Happy to answer any questions!
EDIT: also, I can hear buzzing on your rocket, means the combustion is very unstable. This is a problem with HREs but can be greatly mitigated with a pre and post combustion chamber. Also to fly, you really do need a proper nozzle.
As a general rule, solid hybrid fuel should be quite opaque. If the fuel is translucent, infrared will heat all the fuel rather than only that directly in contact with flame. Wax is problematic, except for very short tests. One might do well to use HTPB with .5% carbon black at first, as adding metal powder makes matters a bit more challenging.
+nabil iben-sobih the go-to material for nozzles is graphite. Throat temperatures are quite high, and graphite will resist it if anything will - won't melt or spall, and are usually reusable after a simple cleaning. You can get fancier with larger nozzles with graphite liner and lesser materials for the bell/bulk of the nozzle. While graphite is somewhat expensive, you can go to "nozzle plates" (multi-venturi), where the graphite is a relatively thin circular plate with multiple small nozzles bored through. Weight and cost savings of as much as 10:1 can be achieved this way, venturi profile is less critical,/faster and performance loss over a single nozzle is usually minimal.
Full size single nozzles need lathe machining, preferably CNC. Nozzle plates can be done with a drill press, and quite minimal manual lathe work.
Most commercially made amateur high power solid and hybrid motors use graphite.
How do you get into the field of research like this ? I'm not gonna pretend like I am a expert or understand all the science behind rockets and space craft.
@@jillvalentinefan77 Are you referring to me? I simply got interested in rocketry beyond model rockets, read the relevant books, happened to have a number of friends also very deeply into the hobby. One of them designed, built, flew and sold (to others in high power rocketry hobby) "solid core" and hybrid motors into the 2000+ pound thrust range. Another was experimenting with tri-fuel/hybrid motors. We all wanted to build various designs of our own, and a local highschool had us show up for every machine shop adult course every summer for several years. We used to joke with the teacher that he must have failed miserably in teaching us, because we had to keep coming back. The whole point was to get access to decent machine tools.
Part of what happened is that we all ended up making parts for each other's motors. It was our interest, so we had to understand *what* the part was for, and how it was designed. So we taught each other what we had learned in our various inherent specialties.
I've made graphite nozzles both of the single venturi and "plate" varieties, for combustion chambers up to 8" in diameter. I've built combustion chambers for solids and hybrids, pre-heat shrouds for tribrids, interstage modules, electronics subsystems etc. Assisted in the manufacture of several kinds of rocket fuel, etc. Test engine fires, ground support, Launch Control Officer and so on.
I wasn't quite bitten with the same level rocket-bug as the others, so my projects weren't quite as adventurous as theirs were, but I ended up understanding just about as much as they did. They pushed the envelope more than I did, and as a result had more failures than I, but, that was okay by them too.
One of the things you learn in life is that people who do things they enjoy (which is what a hobby is), can often understand things far more deeply than those just drawing a pay cheque. It's not work, it's play. Even better if you can get paid to do something you'd happily do as an unpaid hobby.
The best way to learn about basic rocketry is to get bitten by the high power rocketry bug. You can fly Estes rockets without learning a thing, but to successfully fly level 3 high power (my level of certification), you *have* to learn quite a lot, no choice.
If you want to start, if you're very lucky, you'll have a high power rocketry group in your area and go to their launches, ask questions, and get yourself started. If there's no high-power group, look around for more serious model rocketry groups. They'll usually have a high power afficionado somewhere looking for some company.
TIL: anything is a rocket if you throw enough oxygen at it
What I was thinking lol
Or fluorine, which can burn with concrete
Yeah, just put some oxygen up someone’s but and put a fire in their mouth and boom!
The sausage triangle is a very good fuel. The oxidant may be N2O. The video is more about regulatability through pure oxygen, which is a good concept, but in reality it is necessary to first heat the fuel and it takes some time. Repeated ignition also requires several ignition attempts. Hydrazine engines can ignite themselves with a platinum grille even under vacuum. It is therefore very fast, safe and reliable. Therefore, it was used in the Apollo lunar return module.
Justin Clonts turbojet engine is the simplest engine type
Hey thanks for watching! I'd like to hear from you what you think of this more casual style of video compared to what I've mostly done in the past where everything is strictly scripted and overdubbed. Had this video been made in the way that I am used to it would have likely been much shorter and concise, but also contained much less information. I intend for most of my project tutorial videos to still be made in the same way they always have but this new format is something I've been playing with for my last 2-3 videos to see how well it's liked. Thanks to my Patreon supporters once again! Take a look at my page here and consider supporting my videos if you enjoy them: www.patreon.com/NightHawkProjects
NightHawkInLight dude your vif was erpic
NightHawkInLight early as fuck right?
NightHawkInLight love the longer, more casual format!
NightHawkInLight This longer/casual format is perfect!
Your production quality is always very high, so I prefer this type, since it saves you so much time... :)
This is amazing, thanks for sharing!
I'm not a scientist, but I'm fairly certain the visual effect of the rocket core shrinking is caused by its IOR (index of refraction) decreasing as the temperature increases. As the temperature of the acrylic increases, its permittivity (also called dielectric constant) decreases, therefore so too does its index of refraction. The image seen through the transparent surface is becoming less refracted.
Fantastic video! I guess you also learned in the process of making this video, how quickly those Home Depot/Lowes O2 tanks discharge for 10 bucks. :-)
I decided to use your idea of this engine. I decided to make it a jet engine, with an after burner. Took a lot of time but I did it, a fully Manual throttle lever. I also made a auto starting sequence, I loved remaking your project and making a jet engine out of it. It uses jet fuel that I bought, really loud and produces a pretty good amount of force.
Glimple Bort what chemical actually is your jet fuel?
where did u buy the jet fuel?
@@christian_scr Obama
UGGHHH!!!!!! I want more!!!! I’m so much learning in this channel. Thanks bro. God bless and may we learn more from you.
You did a better explanation of a solid fuel rocket than any other ones I've seen, love it!
I learnd more from you than most education channels on tv
Referred to the same video for inspiration for my final year project ! Cool to see someone remaking it again. So much fun!
I would love to know if you measured the thrust of your rocket engine. I'd like to see how it varies with the "throttle". I also believe with a throttled engine like this you can never have an ideal DeLaval nozzle shape across the throttle range. The nozzle shape will only be good for a certain thrust and not another. You would probably maximize the nozzle for full throttle operation in a practical application. Anyhow, I like the style of video. I really like the detailed science explanation. I also love this subject matter. I would love to see if you can make a liquid rocket engine, Cody from CodysLab was working on one a while ago but has not done any videos about it recently.
I have not measured the thrust. Building a device to do so might be a future video if this one does well. I agree that there's no such thing as the perfect nozzle for a rocket with variable thrust, unless the nozzle is also variable. Mine was pretty bad though for any range. I'll make a better one if i try again.
I'd be curious how much of a difference in thrust a well shaped nozzle versus your crappy nozzle actually makes.
Epithemeus Look up Convergent/Divergent nozzles. When done correctly, they can give many times the thrust of a cylindrical opening.
NightHawkInLight I've built a simple low cost electronic thrust measurement system. I have the build and everything on video, I just have not edited the video for upload to my channel. If you do one, I'd be happy to help.
Aerospike nozzle. Solves a lot of problems.
ARE...........YOU............A..............ROBOT
Just putting 'Rocket Scientist' on my CV now. :P
I loved how detailed the video was, I do enjoy you explaining things in a quick and easy understood fashion. The information is compressed in a way I can listen, and it's pretty hard for me to concentrate on things.
Keep the good work.
Does the core look like it's shrinking as it catches fire because its index of refraction changes as the surface heats up and melts?
You beat me to it. As it goes molten its refraction index changes. Great mind urdnal.
urdnal Uhh .... yeah... okay. If you say so. 🤪
Really?
I was thinking about simply moisture vaporizing away but ok einstein
@@tako1257 Where would the moisture come from?
Heating is a very known method to restore car lens, CD surface restore, etc. The shrinking effect it´s because heat produces a polymer chain re-arranging as the material goes to a fluid state. Very nice video!
The core flame is melting the machining marks that make it look opaque, and keeps it in a liquid state once burning, so you can see right through instead of seeing the light deflected off the rough machining marks.Much like you'd do by spraying water on a frosted glass with a cold liquid inside. It looks like it's shrinking because the necessary temperature to make the acrylic melt and burn with the oxygen, was acquired from the tip backwards because the ignition source is at the tip. As the interior started burning with the oxygen, it traveled back until it reached the source of the oxydizer. That good enough?
Incorrect. The acrylic is melting and changing its index of refraction. This is probably the overwhelming contributor to this optic effect.
Hey NightHawkInLight, a quick critique/suggestion on your nozzle. if you look at the video, the exhaust isn't attached to the wall of the nozzle. This is flow separation, it happens when the pressure of the gasses in your exhaust are too far below atmospheric pressure, and the atmosphere forces it's way into the nozzle and pinches down on the exhaust giving you that little jet coming through. It's a pretty easy fix though through trail and error, just slowly shrink the outlet diameter until it sticks back to the nozzle wall. Also I'd shrink the center hole to about 7/8 of what it is now.
edit: looking at it again, it actually seems like the pressure inside the acrylic tube is too low, so maybe an easier fix would be shrinking the diameter of the center hole to increase the pressure.
Regarding the apparent shrinking of the hole, here's my take. For a start, the hole appears bigger than it actually is because the surrounding cylindrical piece of acrylic is acting like a magnifying lens. At room temperature, the refractive index is about 1.47. As the layer of acrylic near the burning center heats up, the refractive index drops (in most plastics, the index goes down as the temperature goes up). The magnifying effect is then reduced, which makes the hole appear to shrink. Hope that makes sense!
I think you are right I just wrote a comment basically saying the same thing before I saw yours.
Nice! I was comment searching for an answer. My best ideas had been uneven thermal expansion due to an uneven heat distribution, but the apparent change seemed to quick for that. One other idea I had tumbling around was that maybe a fusing of all the scratches and cracks from drilling allowed the clarity to extend further in.
Learning the basic for aeronautic physics with NightHawkInLight huh?
This is gonna be really useful to me!
"A friend gave me some random bits of graphite" - rocketdweeb cries in envy
That was absolutely fantastic. I am by no means a scientist but understood this video anyway.
Please build a Hybrid Rocket that can fly, and if you can, put a goPro on it
i am.
@@justanotherasian4395 You don't.
ROCKAT Nani
@@justanotherasian4395 You're building a prototype but It doesn't flies yet.
@@中二病-y5j YET. I said im building it i never said it was complete
My take home from this was anything that can burn can be moderated in the presence of varying degrees of oxygen, I wondered how the plastic rocket fuelled engines work. Thankyou
Is anyone else on here really annoyed when movies/TV use oxygen tanks as an explosive, because they say pure oxygen is an explosive? I love how you show how bogus that notion is!
ayee, i know you, as well as i agree with you're statment, i whould give anything to see a movie with 100% accurate science.
An enclosed container of any gas under high pressure can be 'explosive' if heated high enough. Even water heated in an enclosed tank would be...even a water rocket tank will mechanically 'explode' if the pressure was high enough.
USWaterRockets I think what you mean is the big fireball you see in the movies, and yes it is extremely annoying. Only flammable compressed fuel can create a fireball
USWaterRockets who does that
Deadpool just did it. It's been done before in more obscure shows/films.
Damn, I've been subscribed for years and never spotted this video - just what we need in the UK where hybrid rocket engines are the only ones you can really build legally.
Very interesting and awesome rocket
Make a graphite holder to encase the entire thing along with a couple of graphite/steel screws to hold the nozzle and the holder together. Make a bunch of those acrylic "fuel rods" but drill a hole at the side for a fire to be lit through an ignition coil. make 4 of those and attach it to a go cart with some excellent rudders/steering mechanism. I would love to see that, great job man! Also make it such that the acrylic fuel rods can be replaced easily so the go=cart can be re-used. If you wanna use this for an aerial vehicle you'd have to develop a very efficient way for refuelling XD
I watched this video a while ago and it still blows my mind. Awesome job nighthawkinlight
It doesn't shrink, it's just the refraction changes due to liquification of the inside wall of the combustion chamber.
+James Di I think he was referring to why the burn regression rate at the forward end of the chamber was slower than at the back (nozzle) end.
This is largely because the velocity of O2 is higher at the head end, and the OS s focussed more to a fine jet. As the O2 jet flows towards the back, it's slowing down a bit, expanding, and hotter (preheated). Which causes the acrylic to burn, and hence regress, faster.
You can see a somewhat analogous effect visually at the nozzle itself, where the flame is not expanding to match the really coarse pseudo-taper he drilled. This is "classic" underexpansion of the exhaust.
In more serious rocket design, not only does the nozzle venturi have to be precisely shaped to produce optimal thrust, you'd also shape the gas injectors to try to better balance the regression rates.
Machining precise curves in nozzle venturi is quite hard if all you have is a manual lathe, rather than full CNC. In larger amateur hybrid motors they often "cheat", and instead of a single venturi, in a big fat chunk of graphite, the nozzle is often a much thinner graphite plate with numerous smaller venturi . This has two advantages. The shape of each venturi is less critical, and it's a much smaller chunk of graphite - cheaper and a lot lighter.
As a side note, while Nitrous oxide is rather more difficult to obtain than O2, and isn't quite as energetic as O2, it is FAR SAFER than O2 in large part because it's not so aggressive.
Secondly, since N2O is quite easily to liquify at room temperature, the oxidizer tank in an amateur hybrid doesn't need to withstand as much pressure as a O2 cylinder. It's effectively impossible to have liquid O2 at room temperature (it's vaporizing off at a horrendous rate) no matter what pressure you have it at, and for gas, you need much higher pressures to have nearly the same oxidizer capacity - MUCH heavier tankage.
Further, by careful calculation you can pick the ideal injector size, so simple Nitrous liquid -> gas evaporation provides the pressure you need to run the rocket combustion cycle, and the pressure remains relatively constant until the nitrous runs out. Flying amateur rockets with liquid O2 is impractical (not to mention quite dangerous), very difficult to obtain, and if you use gaseous O2 in the tank, the delivery pressure varies wildly, and the thrust is no where close to being consistent. With O2, you generally have to use liquid O2 and pumps to get consistent thrust.
O2 is ideal for demonstrations like this, where the overall visualization is more important than optimal thrust. But if you want to do high power rocketry with reliable and consistent thrust, DO NOT use O2, use nitrous. Leave O2 to the big boys with big bucks..
And KOR, love you guys. Keeping the light alive dudes. Well done.
Not only will a poorly designed nozzle not produce optimum thrust, it might not even generate significant amounts of thrust at all. The nozzle throat needs to accelerate the gas to sonic, then expand it supersonically. In order to get sonic flow in the nozzle, you have to have at least 30-40 psi chamber pressure, which it looks like you didn't have since the nozzle was just press fit over the chamber. Thrust is linearly related to exhaust velocity, so if you aren't getting at least sonic flow, don't expect more than a pound of thrust at most.
It's a good working model of a tube, burning from the inside. It is not rocket, it is not a rocket model.
I mean, the title says "Hybrid Rocket" so I'm not sure I follow
It's a conceptual model, not a functional model, meant to be built by people at home. Will it launch a payload? No, it wont. Will it teach a child, or function for a demonstration of, how a rocket engine combusts, while making a fairly impressive visualization? Yes, it will.
I'm pretty sure he knows the has little to no thrust, but it DOES explain the concept of hybrid rocket engines.
Thrust is not related to exhaust velocity, specific impulse is. Thrust has many variables, e.g. nozzle size, shape, expansion ratio, type of propellant, pressure in combustion chamber etc.
KersZZ Thrust is absolutely related to exhaust velocity. The thrust equation is T= mdot*v_exhaust +A_exit(P_e-P_a). And for an optimized nozzle with Pa=Pe the only participant in the thrust equation is massflow times exhaust velocity. Isp (specific impulse) is simply exhaust velocity divided by 9.81 (g).
Very impressive! I'm a student at a Swedish university and currently working on somewhat similar hybrid-rocket-related projects for both my masters thesis and in a separate student project. To answer your question about what happens at 8:28, I believe this is the fuel grain forming a fuel vapour zone, with heated and vapourized fuel flowing inwards into the oxidizer stream where it is ignited. Because it is not hot enough to glow, it gives the impression of the fuel grain 'shrinking' but if one looks carefully, one can faintly see the 'real' edge of the solid fuel grain which is regressing outwards. For an illustration of this, see page 589 (figure 15-7) of G.P. Sutton's Rocket Propulsion Elements, 7th ed.
Awesome video. Could a less efficient version be made using regular compressed air?
No. Because air is only 20% oxygen the other 80% will cool off the fuel as it blows past faster than the oxygen can feed the flame and the rocket will go out.
NOx (laughing gas) might.
it's N2O
Amazing ... I thought I was going to be bored out of my wits, but I really learned something today. The charcoal and oxidizer mixture caught my attention. Good job explaining how all this works.
How to attract the attention of the FBI, CIA 101.
You do realize you can buy far more powerful rocket engines pre-made for model rocks right?
@Pen is the funny thing is you dont have to search for any dangerous and in some countries illegal stuff because youtube rubs these videos under your nose until you watch them to get rid of the youtube suggestion xD
+Anubis Why would he thrust you?
Nah. It's not like they really have any legal methods for just tracking people down for looking up this sort of thing.
Yes, I love my model rocks!
Totally awesome video, we used to mess around with that stuff in high school!
Acrylic tubes Bring back memories for me. When you drilled that tube It brought back memories from high school, because when you would grind on acrylics, there is a certain smell comes from manipulating the acrylic ! Awesome video 10 thumbs up by Roger Ebert
I would guess some pretty foul fumes. Good ventilation is key here... Cool rocket motor.
Cool video, I actually learnt something from RUclips today
Need to figure out how to make these into an rc model
Good job, great view of the inside. Don't worry about the nozzle being perfect on a "proof of concept" motor. Going bigger than optimum keeps the thrust down and gives a longer burn time, both desirable when you just want to burn it and see how it does. I'm not sure exactly how they determine nozzle size on a hybrid, but on a solid motor, it's some serious math. On a hybrid, you do have another advantage in that chamber pressure is limited by the oxidizer pressure so if your nozzle is too small, you just need to use a oxidizer pressure within the working limits of the motor casing and it won't overpressure as it would if it were a solid propellant. (chamber pressure at or above oxidizer pressure will cut off the combustion)
Loving the new style man, keep it up!
NightHawkInLight you have really inspired my son some much thank you :)
Awesome, what's the powdered oxidizer you used with the charcoal? Was it Potassium nitrate?
yes it is
Ynze Selders maybe potassium chlorate?
Indeed, probably potassium nitrate. Potassium nitrate + sulfur + charcoal is black powder, the propellant most often used in fireworks.
In amateur rocketry is it also popular to use sugar as a fuel (rocket candy), again with potassium nitrate as oxidiser.
He said in a comment above that it is actually KNO3
Ian Soede Yes, I was reinforcing the idea... wtf ahah
IT WAS AWESOME. I GOT SUCH USEFUL IDEAS TO MAKE A ROCKET.
How much actual thrust do you think the engine produces?
that was freaking awsome! thanks to you patrons for paying this guy!
What was the powdered oxidizer made of again? Sorry if i missed it :/
There are many solid oxidizers. The one i show is potassium nitrate.
Big or small, metal, generally powdered spherical aluminum, is the fuel and needs a binder like HTPB or PBAN to hold the powdered oxidizer, and the metal together. The binder also burns in the process as a fuel.
Toast the oxidizer is most likely potassium nitrate because it is very easy to get. you can get it in some tree stump remover if you get the right brand.
Since you like Wiki, here is also an excerpt on Space Shuttle Solid Rocket Booster or as you said "...the very stuff NASA boosters use":
'The rocket propellant mixture in each solid rocket motor consisted of ammonium perchlorate (oxidizer, 69.8% by weight), atomized aluminium powder (fuel, 16%), iron oxide (catalyst, 0.2%), PBAN (binder, also acts as fuel, 12%), and an epoxy curing agent (2%).[7][8] This propellant is commonly referred to as Ammonium Perchlorate Composite Propellant, or simply APCP. This mixture gave the solid rocket motors a specific impulse of 242 seconds (2.37 km/s) at sea level or 268 seconds (2.63 km/s) in a vacuum.
The main fuel, aluminum, was used because it has a reasonable specific energy density of about 31.0 MJ/kg, but a high volumetric energy density, and is difficult to ignite accidentally.
The propellant had an 11-point star-shaped perforation in the forward motor segment and a double-truncated-cone perforation in each of the aft segments and aft closure. This configuration provided high thrust at ignition and then reduced the thrust by approximately a third 50 seconds after lift-off to avoid overstressing the vehicle during maximum dynamic pressure (Max Q)"
And directly from an academic source can be found this excerpt from Sutton's 'ROCKET PROPULSION ELEMENTS' 7th edition on pages 475-476:
"3. Composite propellants form a heterogenous propellant grain with the oxidizer crystals and a powdered fuel (usually aluminum) held together in a matrix of synthetic rubber (or plastic) binder, such as polybutadiene (HTPB)*. Composite propellants are cast from a mix of solid (AP crystals, Al powder)* and liquid (HTPB, PPG)* ingrediants. The propellant is hardened by crosslinking or curing the liquid binder polymer with a small amount of curing agent, and curing it in an oven, where it becomes hard and solid. In the past three decades the composite propellants have been the most commonly used class. They can be further subdivided:
(1) Conventional composite propellants usually contain between 60 and 72% ammonium perchlorate (AP) as crystalline oxidizer, up to 22%aluminum powder (Al) as a metal fuel, and 8 to 16% of elastomeric binder (organic polymer) including its plasticizer."
(2)-(5) talk about other formulations that can include RDX, nitroglycerine, etc for higher energy ( Isp ). You can reduce or even eliminate aluminum from APCP but at greatly reduced performance relying only on the binder as fuel.
The "shrinkage" that you see in the acrylic tube is just the flame smoothing/polishing the uneven marks made with your drill press.
How loud was that graphite capped rocket engine
If I had to guess, either the acrylic itself is expanding from the heat, or the opaque layer of acrylic leftover from friction with the drill is being melted and returned to a more transparent configuration. As the point of combustion moves backwards, the source of heat moves backwards and thus the effect.
lensing from the case itself is probably exaggerating the size of the layer so it looks like the core is dramatically shrinking/opaque layer is very thick when its probably only a small amount.
I could figure it out with two minutes of hands-on testing, but that's my best guess for you from looking at it here.
You look like Ted Crus with a beard and mustache
*Cruz
Huh? Ivan that was a compliment....
enjoyed the video. Small point however - the oxidizer just needs to grab an electron with great force ( very simply put). it does not need to release oxygen but it does what oxygen does in a Redox reaction.
Dude look like Ted Cruz's son
he looks more like Shia Lebeouf tbh
SR71Blackguy Shia is bae you shut your mouth
I watch all your videos I really like them I really like how you edit, and the way you enunciate when you're speaking.
i would install it on my wifes bicycle
No No No, that would be crazy dangerous for her............ ; -)
@@sonnyburnett8725 "; -)"?!
I love this new format, it contained much more detailed information! thank you!
HE LOOKS LIKE TED CRUZ
I first thought "Hey, Will Wheatons brother!" But now Ted Cruz can't be unseen...
he is so relaxing to listen to.
Why is this probably forbidden in Finland? It doesn't harm anyone.
Why is EVERYTHING forbidden in Finland
The Crow But you can build rocket engines in USA so why not here?
xWood4000 socialism ;) what's good for one is good for all, what's bad for one is bad for all. Risk of injury, risk of death, risk of weaponization. Banned.
Stop with this train of insults or I will ban from the channel.
civil law confirmed.
I knew from the image exactly what it was you made, even before watching. Thanks, Scott Manley!
how much thrust does it make
I didn't have a setup available to measure it. Due to the inefficient nozzle probably only around 5lbs. Acrylic isn't an ideal fuel in any case, it just makes a good demonstration because it's clear. Using a good nozzle, proper fuel, and an oxygen valve that can dump oxidizer quickly you might be able to get in the range of 50lbs of thrust out of the same size rocket.
Couldn't you have rested the rocket against a weighing scale?
Why are People disliking this? It is interesting and cool!
*YOU CAN SHUT OFF A SOLID FUEL ENGINE* all you have to do it cut it in half before the side thats burning reaches the end or top
ive had to before.. lol
well if ya think about it that way i suppose lol unless you throw the burning chunk immediatly into water
Very safe, very easy and definitely something you would do in a flying rocket to modulate the thrust lol !
Not to mention a lot of solid rocket motors are burning their whole length at once.
nice dude thanks
GREAT....Very nicely explained...I'm fasinated with Hybreds
That is a very good, educational video!
However, aren't you a bit concerned about wearing gloves when holding something under a drillpress? It was strikty forbidden in our metalshop to do so.
When the thing is round it can't hurt you if it gets caught and start spinning so it was ok not to use gloves in this particular instance.
"[...]so it was ok not to use gloves[...]"
Right, NOT wearing gloves on a fast spinning machine is what I was told to do.
Reread my comment not only the part you're interested in.
Oh my god, the irony.
Looks like your god didn't help you learn English
Thanks for putting in the time and effort for this video.
It is really sad that firework rockets are getting replaced with bombs.
citation needed
Your videos are like primitive technologys vids. few and far between but I wait patiently and am always entertained! Great Vid!
it seem to pulse a bit no?
I know this is a year late, but the pulsing effect is likely due to shocks. When a nozzle is not ideal, shocks form inside. When a shock forms there is a pressure difference from one side of the shock to the other. This pressure difference causes the shock to move, because the conditions by which the shock formed are not the same. The shock eventually exits the nozzle and a new one forms. This is likely what is causing what you are detecting as the pulse.
@@rogeredge1604 2 years *
@@orkanozgur3749 Thanks. Last month it said 1 year.
8:16 Flame polishing, the high temperature melts the machined part and produces a clear, smooth finish. Look it up ,it's cool.
like the vid.. But come on man. At 9:00 min.. That's a recipe for getting your finger ripped of or degloved..
Those are nitrile gloves. They're thinner than a piece of paper and are way too weak to drag your hand into a bit.
NightHawkInLight
I know.. I'm worried about his hand.
Wouldn't do that barehanded.
bruh yeah
xD ya
I really appreciate Will Wheaton for doing this video. It just shows that he's more than just a pretty face who appeared on Star Trek once or twice.
;-)
it isnt rocketscience, oh wait it is.
Man, your macro shots are amazing.
ow man you make me cringe because your holding the nozzle while drilling it, and i advise not to do that.
The drill press is not very strong. It can be stopped by hand the way I have the belt routed.
love how you're holding that tube most of the video ;)
I love your videos! I like how you held that plastic tubing in front of you for almost five minutes, for no apparent reason! 😂
Loved your Video! And you seem to be a likable chap!
Try using N2O cartridges for a better oxidizer. It will also keep the weight and size down since they are about the same size as CO2 cartridges. This will help you if you want to get airborne hybrid rockets.
N2O is a better oxidizer in rockets than O2 due to it's ability to be liquid at a higher temperature correct? So better density?
+Nathan Campbell That's what i thought
NightHawkInLight Yea, basically it has a more efficient exothermic decomposition of the oxidizer molecule compared to O2.
Nathan Campbell how to fit a bomb on a rocket and hit it on the target ?or atleast far away ? 😊
The core looks the way it does because you are basically flame polishing a tube. With acrylics you can turn a matte edge completely clear with a quick burst of high heat run along the edge. So whats happening here isn't that it's catching fire but the heat builds up to the working temp for it to polish and smooth off. So rough and opaque to smooth and transparent! ;D
8:29 I think it changes from cloudy to clear because the drilling cause scratch marks on the inside. But when the engine turns on, the scratches have a high surface area and burn away quickly.
Another great video by nighthawkinlight
excellent explanation of everything
Thank you senator Cruz !
These video always amaze me! Thanks NighHawkInLight and thanks to have help smartereveryday too for his last video! Colaboration make great stuff!
thanks for making such nice educational videos..I actually learnt a lot of stuff about the thrust of rocket ..and such channels should really grow if science lovers exists..😃
the acrylic burns on the inside or appears to be boring due to something i remember as flame polishing. Im not 100% sure if thats what it is but usually when making acrylic fish tanks we use a torch and burn it to make it appear clear in areas that are not visible. such as when we sand the side or like how you drilled through it. I do believe thats why the acrylic appears to be burning
I think the shrinking of the inside is due to diffraction. When you drill it it leaves a rough finish which just diffuses the light but when it is melted it gives a clear smooth finish and as it is a curve it diffracts the light more.
Nice work. You could try to make a mechanism that holds the flap cap onto the barrel. It might be too slow because starting the moment the projectile is released, the flap could start leaking air. if you manage to only open at high pressure, the flap can make optimal use of the energy to open quickly as all the air to push it open is still in the tube. This, just like the alu cap will cost energy as the projectile will hit a compressed air bed just before it comes out. But is will give you faster reloading. Add a small magnet on the plunger and the projectile this way you can make the diameter of the projectile bigger so that you have less air leakage during the forward movement of the projectile. The fact that you could add tape tells the projectile is not snug enough in the tube.
incredible work sir
thank you giving this information and your theory is very good ....keep posting this kind of video
Thanks for all the work you put into producing these videos. You do a fantastic job on them and I learn a lot on all of them. Keep it up!
It looks like it shrinks because the cut you made in the middle roughened the surface of the inside of the acrylic tube making it less see-through. When you started burning it it burned away that rough layer and made it see through like the rest of the tube.