This video may be an example of my ability to make a simple concept complicated, but I'm sure if that's the case you'll set me straight in the comments. It took longer for me to finish with this video than it should have. Hopefully it's entertaining and gives you something to think about even if my own conclusions are less than decisive. I'm excited about other projects I have coming up, so stay tuned.
It looks to me like the firework fuse feeds in not just into the side but is also following the curve at a slight angle, maybe due to being wrapped into the paper or cardboard housing. This would give it enough thrust in that direction to effect the top-like spin that causes it to right itself before the main rocket fires. Then the spin acts as a crude rifling, giving it a stable line upward. It would also answer why the first is offset instead of centered; a middle mass burst would not allow for stability on an end and it would likely fire off randomly in one direction once the secondary kicked in.
2 things. 1 - it looks as though they're also weighted heavier towards the 'nozzle' end via a thicker clay wad & 2 - I further suspect you'll never truly understand how they work until you 1st build one & then improve on the design of them..... ..challenge extended?..😉
3:03 Awfully considerate of that glass to wait until the test was finished to crack. Honestly, though, I think you've hit the nail on the head with your revised hypothesis (not so sure about the tippy top one). Don't sell yourself short, either.
its the cooling of the glass that causes it to crack, not so much the heating. hence why glassmakers have to anneal their glass and cool it slowly over several hours in order for it not to crack / shatter.
@@yeet1337 i think so. im not 100% on all the details, but when I was at uni doing glass work they had big ovens that you put your work into so they didnt cool too fast and crack. with the heat being so focused on the glass pane and the rest of the pane being cool id say there would be a high amount of internal stress in that glass and even just a small temperature change would possibly causes the cracks to happen. im not an expert on it tho, just something I learned when I took glass as an elective at art school.
those are so fun! I always buy a few a few packs every chance I get. Ive wanted to slowmotion these for awhile but never got around to it. Im glad you did because you did it better than I would have :P Ive always thrown them when the fuse is almost done. they take off in very unpredictable way and its always a mini heart attack when they zip past your head.
The way it appears to me is that the hole in the side of the tube is not at a normal to the side but angled slightly, It is also not centered on the length. This gives the tube a spin along two axes, but it will preferentially spin faster about the axial center (think about the famous example of the ice skater spinning and bringing their arms in to spin faster because the mass is closer to the axis of rotation). The offset nozzle along the side gives thrust that also tries to rotate the tube somewhat perpendicular to this, but the tube is spinning axially so much faster that the radial thrust is only going to wobble it since the radial thrust will be rotating about the axial rotation and cancelling itself out since the thrust vector is constantly sweeping around the tube. However, the "ground effect" will tend to provide a larger radial thrust whenever the nozzle is pointing to the ground, so this will cause the radial thrust to be imbalanced when it is pointing down. The imbalance causes the lengthwise offset nozzle end to lift until the tube is closer to vertical and the ground effect cannot cause the imbalanced thrust. The tube at this point is nearly vertical but wobbling as the radial thrust is more or less the same as it rotates around the axial center. Now the bottom nozzle fires and shoots the whole thing up at a somewhat vertical angle. I hope I explained that well enough.
Do they spin in the same direction every time? That would be a good indicator of factory design rather than crude (albeit effective) construction. Seems like they did for the most part, but I might rewatch to check.
I had the same thoughts with the 2 axis offset on the thrust. the hole, and fuse, is notably drilled to one side of the tube, not dead center. and the ground-effect for righting the spinner. Of course once its spun up and upright it likely takes advantage of the gyroscopic effect to stablize it. especially since its spinning much faster on the narrow axis, than the wide one when its laying down. Which is also different from the ground spinners.
What I would like to see is placing the firework into a wheel bearing. Get a wheel bearing that has the same or almost the same ID as the OD of the firework. Lite the firework and film from the top. This will let you know if the burn is on a slight angle for the spin. If it is my guess is your guess could be confirmed.
I think I was thinking similar to what you explained but thinking of the firework as more of a gyro. As it spins on the axis you described, like a qyro, it will want to upright itself and stay on the center of the length. As it stands up, the wobble becomes less and less and by the time the bottom ignites it's almost standing straight up and down. With the continued spinning from the initial stream the tube will stay perpendicular to the ground (or flat surface) and the second blast sends it straight up. Just my thought.
I would also think to look at the firework head on to get a look at how far off the first initial jet is from 90 of the center axis of the firework itself, so even a small degree one way or the other would help the effect of getting it to spin, the ground effect helping to push it up on its tail end and start to spin like a top, and by that time it is pointing up and the secondary rocket kicks in, launching it into the sky.
I enjoyed thinking about this along with you in the video - the thought process journey is as enjoyable as any conclusion we may eventually reach. As a further experimental idea, I suggest trying to spin small cylinders on a flat surface, with no rocket thrust - I feel like there is something about the geometry of the contact point with the ground vs the rotation of the object that tends to drag the cylinder into an upright position
Clearly the alignment of the side nozzle provides a significant thrust vector tangential to the circumference of the cylinder. Combined with it's orientation relative to the CG, that's going to tend to make it stand up. If the thrust was also angled axially toward the CG, ti would make the object want to take off, without any help from the jet on the end. That said, it would require much more thrust, and it wouldn;t be as fast or impressive. This configuration would be much cheaper and much more exciting, which, after all, is the point.
As a mechanical engineer, I am in love with this design. It uses friction, the asymmetry of floor/sky + actio/reactio ("groundeffect"), conservation of angular momentum... all in a beautiful ballet with redunancies that lasts just a tic longer than a blink of an eye.
I'm a physicist, you're correct in your assumption with the spinning top. Horizontal rotation isn't energetically favourable, so that's why it eventually rights itself to vertical. But it's a very chaotic system so there will be a lot more things going on, but the angular momentum component will be the main explanation.
I think the secret is the hole formed by the fuse, and later the side exhaust, is not bored straight into the center of the tube. It is angled off to one side. This causes the exhaust to start a twisting motion which forces the tube to start rolling on the surface. When the exhaust starts firing down into the surface, that forces the tube to stand up. Now that it is in a vertical position the exhaust from the hole on the bottom of the tube launches it upward. Also, twisting motion from the side exhaust also has a rifling effect which will try to stabilize the upward direction of the tube.
Yeah same thought, also when looking at the slow motion i think there is a small time where the side thrust is pointing down(to the longer side of the tube. I think that is based on the positioning of the material with is around the fuse hole and above it. ) maybe this also brings a bit more of the tiny stand up force. To test it you should stick it again on wood and see from top perspective where the bust comes from.
This is great! This effect is basically the reverse of spinning a AA battery like a spinning top! While the rpm of the battery is high it will stand on end but as it slows down the battery becomes less stable and tilts until spinning to slow and lays on its side and stops, a combination of centrifugal and gyroscopic force
As a kid I used to play with empty soda cans. When you lay one down on its side and place your fingeron one ends and press until it slides out from under it, it will start to to spin and it it will lift axially sometimes even standing straight up. I think this is a similar effect.
I would do this in elementary school with crayola marker caps. press down on one side, it would shoot out some distance while spinning rapidly. Usually would lift one side into the air and sometimes finish standing on end..
The Coanda Effect from the off center axis side exhaust causes the exhaust flow to adhere to the side of the cylinder in an angular 2-D fashion. Primarily circumferential but including an axial component pointing to the shorter end. This resulting lower pressure areas combined with the flat surface high pressures in the 2 axes and rapidly accelerating spinning gradually cause the erection of the cylinder. The secondary gyroscopic effect providing basic but wobbly vertical stability. Ultimately the end exhaust nozzle ejection gases erupt providing powerful vertical forces and the firework shoots upward until the fuel is exhausted. I am being semi-serious about this. But, even to me, it smacks of over analysis. Great video. No. A Fantastic Video. This should be shown to anyone with an aptitude and interest in science and critical thinking. One of the best I’ve seen in a while. With no preference of gender, racial or any other category. You either love this stuff or you don’t. You can teach it (force it down their throats) to people who are indifferent but that will be wasted effort. I’m 60 years old and I was glued to the screen to see the slo-mo video and hear your analysis. Unfortunately, that is not what Public and most Private schools are promoting and teaching today. Sorry for preaching but this is a great video. Keep up the great work.
Weight distribution changes with fuel exhaustion. The firework is exhausting it's fuel from one end. So the heavy end is the opposite end. The rotation makes the firework spin like a top. By the time the rocket stands on the heavy end the firework starts jet from the heavy end changing from a top to a rocket.
This is what I was thinking too. Is the firework bottom heavy to start with? As the spin fuel is burnt, the centre of mass changes and the lighter end would lift. To demonstrate the effect spin a cylinder full of clay and it will stay rotating on the same plane. Then spin a cylinder that has only been half filled with clay at one end and the cylinder and the lighter end should lift up if the rotational speed is high enough. The thrust from the fuse hole being offset from both the radial axis and the initial centre of mass gives the tube enough momentum to spin. As the fuel is depleted the centre of mass moves away from the fuse hole thrust causing the tube to lift at the lighter end because as the centre of mass moves, the rotational axis moves with it. At some point the two axes of rotation meet and the tube is now aligned for the lifting charge to ignite.
NightHawkInLight, I saw this before and fell upon this video again. This time I had a fresh look and studied your slow motion videos. One thing I noticed is that the fireworks burns at the top, making the unburned powder below. This heavier weight would tend to be at the bottom and the burning section at the top, like a plumb bob. Then the powder continues to burn and the flame hits the open core which exhausts out the bottom.
What's crazy, is that they are quite a complicated mechanism, but they are reliable albeit being made of crappy cardboard and clay. It should be an inspiration for rocket designers :p
“That was a mouth full of words and every one of them might be wrong.” 😅 First time watching your videos and I am subscribing bc of that line. Doing the work to test the science and still admitting possibility of error! 👍
haha nice man your a pyro dude! i been making fireworks since the 80's! i would say that the bottom has more weight in clay then the top causing the "weeble wobble" effect. the fuel above is also a different composition then the rocket fuel used for lift. also the hole coming out of the side should be entering on a slight angle rather then just straight in but not sure.
Dude, vid and footage is Amazing. The whole thing fluently speaks to my preferred style of learning. First you present a succinct, pithy hypotheses. Then make verbal statements supporting your hypothesis and then the best for last. You SHOW ME how your idea plays out clearly in slo mo. I love pyro and am grateful to you for sharing how things work. It’s a behind the curtain glimpse of how the wizardry of pyro magic happens. SALUTE
an object, if allowed to rotate freely, will do so in the axis of least moment of inertia. MI directly propotional to radius. You are right, in this case keeping jet one eccentric to one side makes the other side heavier, which makes spinning on that side more stable (stable equilibrium) long enough for the second jet to fire.
Flying fireworks were illegal where I grew up. We found a way around that as children that I never understood. We found that if you lit then threw one of the "ground bloom" fireworks into the lake about 50% of the time they would fly out of the water similarly to these fireworks being demonstrated. I would love to see a slow motion video of this phenomenon.
Thank you Ben for always doing a stellar job at explaining what you think is going on and ALWAYS being humble in the process, that alone speaks volumes as to what kind of man you are!👍👍😁😁
Interesting... I might know but am equally unsure... I remember being taught that objects only stably spin around axes of maximum and minimum moments of inertia. Books can spin flat like a frisbee about an axis perpendicular to the pages or side ways around an axis parallel to the spine (assuming portrait format) but cannot be stable end over end. This firework will only be stable spinning on its end as the maximum inertia is shared by two axes sideways through the cylinder. The off-centre thrust especially with ground effect can kick it to transition, as can friction at the bottom like the tippee-top. That’s my guess anyway:) great video
It's a variety of effects that give it it's properties like you said. The main one though is the gyroscopic precession like Euler's disk. And thank you for the slow motion on those, I wondered these things too.
They seem weighted towards the thruster end. Maybe you can follow up with a video where you show the center of gravity while it's laying on it's side. I don't know if you can use bamboo skewers to do that but that is what I would try. Awesome stuff as always! I'm binging your channel during the covid-19 shelter in place. Stay safe and thanks for the great content!
I think it tends to stand upright because the propellant burns from the fused end making it lighter in weight. The bottom end must be where it is because it has still unburned propellant making it heavier. But of course I'm only taking a guess......
@David Barr They aren't right though... There's a giant tunnel in the bottom half... That's way less material then a tiny fuse. Idk how you thought they could be right lmao
@@SylasTheGreat a giant tunnel... through a piece of clay at the base. if you pause it at 3.00 and have a look at the clay on the top part of the bottom section (above the 'tunnel') you can see it angles towards the fuse hole ever so slightly, which I bet changes the centre of balance and spin axis ever so slightly, but probably just enough.
@@SylasTheGreat How is it lighter on the bottom when ignition starts from the top where the fuse is? The other thing to consider is centrifugal force and motion added to the mix.
I felt like a kid again! ))) p.s. Ben, if you want your brain to explode try to figure out a "Spinning T-handle in zero gravity" effect. There are videos on youtube showing this amazing effect (of t-handle spinning in the air and flipping back and forth at the same time).
take the spinning top and record it. now play the footage backwards. that's how the rocket stands upright except rather than normal force it uses a pressurized jet of burning fuel decelerating spinning top versus accelerating spinning rocket both changing angular momentum, transitioning from upright and spinning to laying down and not spinning or vice versa tippy tops work on the same principle but are a different application of it.
To be honest, I think you hit the nail right on the head with that"really long mouthful of words...", That the friction from touching the ground, with the spinning motion creates a simple spinning top type effect, then a short burst from the tiny rocket engine that by necessity is pointing straight down and spinning, no tail needed. Thanks for the video, very interesting.
pls do a collaboration with the slow mo guys or smarter everyday to film even more impressif firework ignition from the inside with your glasplatt technic, it was awesome
As usual a superb video !! I was thinking of a way to test the ground effect.... Maybe you should try the same things you did in the video but on a metal mesh surface. It would allow must of the thrust to go through the surface, so the firework would maybe take longer to stand up right. (the mesh might cause a friction problem ... )
It would be really great (technically difficult to achieve, of course) to see them go off in free air rather than close to the ground. I bet that would help unlock the effect of having that solid plane of the ground causing them to go up. Another idea is to set them off inside a half sphere and see if they tend to go up or more perpendicular to the surface of the bowl. The fact that the flat surface is perpendicular to gravity may be significant. Being able to observe them in freefall reduces or eliminates gravity. Angular momentum is definitely a factor. Changing center of gravity. Air resistance, perhaps even magnus effect to some degree. Probably even The Dzhanibekov Effect.
Initially I imagined it similar to a lemon, where you start spinning it on its side and its rotation translates to the adjacent axis and spins on its end. Then when you mentioned the tippe top I was even more convinced I was correct. But seeing it in slo motion, it seems the side vent it slightly off center so it rolls around and is just pushed upright by the jet of exhaust.
When the firework's initial exhaust is pointed upwards or anywhere pointing up, it pushes the firework to the ground, but there's no downward movement due to the ground blocking it, but when it's pointing down, there's nothing holding against the firework on the upper part, therefore it's pushed upwards. When the firework is lifted up, the gyroscopic precession and other things play their part.
I’m refraining from reading the comments just to keep my thoughts trained on what my intuition was telling me, and I didn’t pick up on you mentioning anything about it: mass! Or rather, center of mass. I’m not a rocket expert, but a center of mass is crucial in getting right in rocketeering (thanks Destin!). I’m wondering if the burned fuel from the spinner nozzle end of the firework causes a shift in mass in such a way to force the firework upright while spinning. My guess is this would cause the center of mass more towards the large nozzle. I also think that there probably is some gyroscopic procession or however it’s spelled that helps exploit the shifting in weight to cause it to be upright. Maybe you could do an experiment that shows a spinning rod (with unsymmetrical distribution of weight to one side) while prone/horizontal, will want to stand up straight with heaviest part on the ground, and lighter upwards. Thanks for the video and for sharing the unsolved problem with others :)
My favorite firework I've ever seen used was dark turquoise blue and said SHAZAM in bright turquoise on the side. Its size was about halfway between one of these and a stick of dynamite, and it was completely nuts. In a crowd of people who loved fireworks and in North Dakota where the 4th of july is world war 3 every year, not a single person there had seen anything like it. Somebody lit it, threw it out in the street, and it spun for a second before it sounded like a jet flew overhead and it shot straight up into the stratosphere and disappeared forever. I've never been able to find one for sale or even in a youtube video ever since, and out of everyone there that day, we all only had the one. A single firework that just totally bamboozled everybody and vanished from our lives forever.
note, patreon email telling me about this video had a bad link to the video. i had to go to patreon and then click on the video link there to get here.
This brought to mind two old youtube videos: "Spinning Tube Trick Explained" by Veratasium, and "Strange Spinning Tubes - Numberphile" by Numberphile. In that situation, the tube, despite not having a rocket on it, still lifts up a little off of the surface.
Kinda figured the thrust imparted rotation around it's length and it pushes of the ground standing it up then firing it's thrust. Figured it out before seeing slowmo :D. In the end you mentioned how it's not just the ground effect though and I believe you're correct. I think the off entered thrust corrects this. If you think about it the thrust will always have a larger radius when it is spinning at a tilt. Just a junior physics major, hope this helps.
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I am looking at this as a spin balanced system very much like a spinning top, as you suggested . The side exhaust is pushing in all directions (with a slight angle to incur rotation), preventing it from falling in any one direction (would imagine speed of rotation is a factor) and once it is semi balanced the flame will simply push it up.
so the first fuse lights, it's positioned to make the tube spin. if the thrust of that gets close to the flat surface, it has something to push against other than the air. so more of the energy emitted is converted into thrust? this then pushes that end of the tube vertically, the spinning creates a gyroscopic effect too, so then it's vertical and semi-stable, it kicks on it's main thrusters! i really love the part when you cut one in half and stuck it on some glass, that looked really cool!
Ahahahaha, i knew it! That slowmo footage got me so excited to see it and confirm my theory. I didnt know how to explain it but i imagined it in my head the same way it was shown, and it made me so happy to see. i love this cannel
I think high speed cameras were invented to frame fireworks, and I love it ! I played with this kind of firework when younger, I had some with two holes on either side of the cylinder, one up and one facing down. The firecrackers flew systematically but only by rotation, it was not a propulsion. I never found them again later.
You should tear one down, remove the fuel, then try and build an enclosing case of your own. Maybe you can design different cases to see how it affects the spin and flight path. I really loved watching this and appreciated the slow-mo sound fx. XD
Love the disc golf basket in the background. Nice touch. You also need to take into consideration manufacturing defects or variances in chemical make up. They are cracking these thing put pretty fast. The nozzle geometry could be different from one to the other. Just my two cents. Love your videos always so informative and thought-provoking.
I must have gone through 1000s of those as a kid. Cool to see how it all worked. - the cut in half glass shots are awesome. (It’s also heavier at the bottom because of the clay and unburned fuel so that may be why it stands on end as the exhaust pushes it up a bit?)
You should refer to some of the (many) videos on the "Intermediate Axis Theorem" This is why the thing stands up and spins. The math is a pita, but it boils down to having a positive feedback whenever there is a deviation on the less-stable axis.
I can tell the internet is wearing down on you. Intelligence doesn't hold a flame to curiosity and willingness to follow the scientific method. I always appreciate watching your videos. You do great work.
I think you got it. I just found those things last 4th of july, been trying to figure them out ever since. All I needed was your high speed camera, thanks.
theory : the cylinder is initially bottom heavy because of quantity or/and type of the second stage propellant.So, while the first stage burns and the stabilizing spin initiates even more propellant is burnt from the first stage /top and therefore when the time comes for the second ,still heavy ,stage to ignite the whole thing has balanced/righted itself on the vertical axis and off it goes . Nice videos as always !
Seems pretty simple. The hole at the side ignites, and it starts rotating. Once it intersects ground once, the momentum kicks it up and further spinning occurs, when the initial charge pierces into the main tube, the mini stabilized rocked pop up. Ingenious and simple. I'm pretty sure it has to do with the way the hole is drilled in the body. Is it offset from the center axis towards the chamber?
ok, my guess is..... the exit hole is not only tangential to it length but as you also pointed out tangentially to its axis. this creates a spin in 2 axis. one of those spins is high energy, axially, and one of those spins, along its length, is low energy and used to help start a gyroscopic procession so that the point of contact will shift as friction grabs hold. because of the spin tangential to the axis it also rotates and when the jet is blowing into air it only has so much mass to push against (and/or is just pushing down in with gravity) but when it rotates about and faces down it has the "ground effect" or something to push against (and/or is blowing in a direction not forcing the body against a solid surface) which starts to stand it up. when it stands up you develop the friction point along its annular face which combines the low energy spin and high energy spin combine to finish standing it up. think 'spins faster, when the procession wants to bring the axis of rotation over the friction point as the friction point is brought under the axis of rotation. because the speed of rotation is increasing as force is continued to be exerted you see the gyroscopic procession work backwards then you are used to seeing (as it gets slower it processes more is now happening in reverse. gyroscopic recession?) this brings the body to line up in a direction mostly up when the launch charge ignites, and, as its still spinning while being launched you now have a rifling effect to stabilize it in flight and through doppler effects and hiding or exposing the noise source on the front or rear side of the body as you view it you get the warbling effect in the sound.
5:24 the first thing I thought was "top". Then the super slow mo and you could see the jet pushing off the ground and starting the uprighting process. Have you measured the angle of the side jet (possible up or down angle besides somewhat tangential - wrong word I'm sure)? Is the bottom half weighted at all? Love your videos and how you explain your thinking and process.
THANK YOU THANK YOU I LOVED IT!! It is so fascinating in SloMo TO SEE how the little stinker (pun intended) orients itself to prep for the launch!! AND, DID I MENTION I LOVED THIS VIDEO!! KEEP UP THE GOOD WORK!!
I think you're on the right track with the friction idea. I used to take batteries and marker lids and such and spin them on the table. What you do is lay ir flat on the table and put your finger on one of the ends. Then you press down hard until it pops out from under your finger with a great deal of spin. It will shoot out and away until you perfect the pulldown and back method. but you'll see it does the exact same thing as these fireworks. It shoots out spinning on its long axis and quickly stands up but then drops back to riding on just the bottom edge of the battery until it loses all of its momentum and stops. Try it yourself. Film it in highspeed even. You'll see it spins up and stands up just like your fireworks only with no thrust from black powder.
I would assume the distribution of the fuel also distributes the weight. The first burn rotates on its axis vertically because it’s mass is decreasing while the second lot of fuel still has all its weight at the bottom.
This video may be an example of my ability to make a simple concept complicated, but I'm sure if that's the case you'll set me straight in the comments. It took longer for me to finish with this video than it should have. Hopefully it's entertaining and gives you something to think about even if my own conclusions are less than decisive. I'm excited about other projects I have coming up, so stay tuned.
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It looks to me like the firework fuse feeds in not just into the side but is also following the curve at a slight angle, maybe due to being wrapped into the paper or cardboard housing.
This would give it enough thrust in that direction to effect the top-like spin that causes it to right itself before the main rocket fires. Then the spin acts as a crude rifling, giving it a stable line upward.
It would also answer why the first is offset instead of centered; a middle mass burst would not allow for stability on an end and it would likely fire off randomly in one direction once the secondary kicked in.
2 things. 1 - it looks as though they're also weighted heavier towards the 'nozzle' end via a thicker clay wad & 2 - I further suspect you'll never truly understand how they work until you 1st build one & then improve on the design of them.....
..challenge extended?..😉
This question has literally kept me awake at night. I do appreciate the difficulty in saying that without sounding sarcastic.
making your own versions of it will prove your theory
3:03 Awfully considerate of that glass to wait until the test was finished to crack.
Honestly, though, I think you've hit the nail on the head with your revised hypothesis (not so sure about the tippy top one). Don't sell yourself short, either.
You can really see heat conduction with the glass. It takes some time and that's really wonderful somehow
its the cooling of the glass that causes it to crack, not so much the heating. hence why glassmakers have to anneal their glass and cool it slowly over several hours in order for it not to crack / shatter.
@@brapamaldi Oh, I didn't know that! Is it because some parts cool down faster than others and the slight contractions cause it to crack?
@@yeet1337 i think so. im not 100% on all the details, but when I was at uni doing glass work they had big ovens that you put your work into so they didnt cool too fast and crack. with the heat being so focused on the glass pane and the rest of the pane being cool id say there would be a high amount of internal stress in that glass and even just a small temperature change would possibly causes the cracks to happen. im not an expert on it tho, just something I learned when I took glass as an elective at art school.
The glass is like ta-dah and then starts shaking it's jazz hands awaiting the applause!
those are so fun! I always buy a few a few packs every chance I get. Ive wanted to slowmotion these for awhile but never got around to it. Im glad you did because you did it better than I would have :P Ive always thrown them when the fuse is almost done. they take off in very unpredictable way and its always a mini heart attack when they zip past your head.
The way it appears to me is that the hole in the side of the tube is not at a normal to the side but angled slightly, It is also not centered on the length. This gives the tube a spin along two axes, but it will preferentially spin faster about the axial center (think about the famous example of the ice skater spinning and bringing their arms in to spin faster because the mass is closer to the axis of rotation). The offset nozzle along the side gives thrust that also tries to rotate the tube somewhat perpendicular to this, but the tube is spinning axially so much faster that the radial thrust is only going to wobble it since the radial thrust will be rotating about the axial rotation and cancelling itself out since the thrust vector is constantly sweeping around the tube. However, the "ground effect" will tend to provide a larger radial thrust whenever the nozzle is pointing to the ground, so this will cause the radial thrust to be imbalanced when it is pointing down. The imbalance causes the lengthwise offset nozzle end to lift until the tube is closer to vertical and the ground effect cannot cause the imbalanced thrust. The tube at this point is nearly vertical but wobbling as the radial thrust is more or less the same as it rotates around the axial center. Now the bottom nozzle fires and shoots the whole thing up at a somewhat vertical angle. I hope I explained that well enough.
Do they spin in the same direction every time? That would be a good indicator of factory design rather than crude (albeit effective) construction. Seems like they did for the most part, but I might rewatch to check.
I had the same thoughts with the 2 axis offset on the thrust. the hole, and fuse, is notably drilled to one side of the tube, not dead center. and the ground-effect for righting the spinner. Of course once its spun up and upright it likely takes advantage of the gyroscopic effect to stablize it. especially since its spinning much faster on the narrow axis, than the wide one when its laying down. Which is also different from the ground spinners.
What I would like to see is placing the firework into a wheel bearing.
Get a wheel bearing that has the same or almost the same ID as the OD of the firework. Lite the firework and film from the top. This will let you know if the burn is on a slight angle for the spin. If it is my guess is your guess could be confirmed.
I think I was thinking similar to what you explained but thinking of the firework as more of a gyro. As it spins on the axis you described, like a qyro, it will want to upright itself and stay on the center of the length. As it stands up, the wobble becomes less and less and by the time the bottom ignites it's almost standing straight up and down. With the continued spinning from the initial stream the tube will stay perpendicular to the ground (or flat surface) and the second blast sends it straight up. Just my thought.
I would also think to look at the firework head on to get a look at how far off the first initial jet is from 90 of the center axis of the firework itself, so even a small degree one way or the other would help the effect of getting it to spin, the ground effect helping to push it up on its tail end and start to spin like a top, and by that time it is pointing up and the secondary rocket kicks in, launching it into the sky.
Admitting that you may be wrong, and others correct, is itself a sign of being smart :-)
I enjoyed thinking about this along with you in the video - the thought process journey is as enjoyable as any conclusion we may eventually reach.
As a further experimental idea, I suggest trying to spin small cylinders on a flat surface, with no rocket thrust - I feel like there is something about the geometry of the contact point with the ground vs the rotation of the object that tends to drag the cylinder into an upright position
Same with a hard boiled egg- spin one flat and it will stand up!
Clearly the alignment of the side nozzle provides a significant thrust vector tangential to the circumference of the cylinder. Combined with it's orientation relative to the CG, that's going to tend to make it stand up. If the thrust was also angled axially toward the CG, ti would make the object want to take off, without any help from the jet on the end. That said, it would require much more thrust, and it wouldn;t be as fast or impressive. This configuration would be much cheaper and much more exciting, which, after all, is the point.
Great idea cutting them in half and gluing them to a pane of glass! You got some really good shots. Well done mate.
Yeah, that had me mesmerized.
true ..true .
Especially seeing a glass shattering.
@@TheRealIHP i saw that and now have to test if i can use these to cut irregular holes in glass. welp guess its time to buy some glass and fireworks
As a mechanical engineer, I am in love with this design. It uses friction, the asymmetry of floor/sky + actio/reactio ("groundeffect"), conservation of angular momentum... all in a beautiful ballet with redunancies that lasts just a tic longer than a blink of an eye.
So now that you understand the physics, it is safe to assume your next video will be a DIY giant speed ball? PLEASE! PLEASE! PLEASE!
You made me realize that we haven't had a DIY firework video from NightHawk in a long time.
@Zephyr Haven Rocket candy would be very nice.
First a diy ball mill for making the BP.
Volvary because UA-cam turned pc and deranks and demonetizes those types of videos:/
Speed ball? No cocaine and heroin does not a good video make
I'm a physicist, you're correct in your assumption with the spinning top. Horizontal rotation isn't energetically favourable, so that's why it eventually rights itself to vertical. But it's a very chaotic system so there will be a lot more things going on, but the angular momentum component will be the main explanation.
I think the secret is the hole formed by the fuse, and later the side exhaust, is not bored straight into the center of the tube. It is angled off to one side. This causes the exhaust to start a twisting motion which forces the tube to start rolling on the surface. When the exhaust starts firing down into the surface, that forces the tube to stand up. Now that it is in a vertical position the exhaust from the hole on the bottom of the tube launches it upward. Also, twisting motion from the side exhaust also has a rifling effect which will try to stabilize the upward direction of the tube.
Yeah same thought, also when looking at the slow motion i think there is a small time where the side thrust is pointing down(to the longer side of the tube. I think that is based on the positioning of the material with is around the fuse hole and above it. ) maybe this also brings a bit more of the tiny stand up force. To test it you should stick it again on wood and see from top perspective where the bust comes from.
could the "bottom" of the rocket have a higher weight distribution also? the side nozzle then pushing it up vertical on to its "base"
Yeah, he never mentioned that at all. Need more info.
This is great! This effect is basically the reverse of spinning a AA battery like a spinning top! While the rpm of the battery is high it will stand on end but as it slows down the battery becomes less stable and tilts until spinning to slow and lays on its side and stops, a combination of centrifugal and gyroscopic force
As a kid I used to play with empty soda cans. When you lay one down on its side and place your fingeron one ends and press until it slides out from under it, it will start to to spin and it it will lift axially sometimes even standing straight up. I think this is a similar effect.
Jackson Cunningham I think you should’ve drink less soda
I would do this in elementary school with crayola marker caps. press down on one side, it would shoot out some distance while spinning rapidly. Usually would lift one side into the air and sometimes finish standing on end..
Jackson Cunningham i cant figure out how this is supposed to work.
As a kid, My parents bought me toys....
Only kidding Jackson.
You can also do this with chapstick! I immediately thought of doing that as a kid when I saw this video.
The Coanda Effect from the off center axis side exhaust causes the exhaust flow to adhere to the side of the cylinder in an angular 2-D fashion.
Primarily circumferential but including an axial component pointing to the shorter end.
This resulting lower pressure areas combined with the flat surface high pressures in the 2 axes and rapidly accelerating spinning gradually cause the erection of the cylinder. The secondary gyroscopic effect providing basic but wobbly vertical stability.
Ultimately the end exhaust nozzle ejection gases erupt providing powerful vertical forces and the firework shoots upward until the fuel is exhausted.
I am being semi-serious about this. But, even to me, it smacks of over analysis.
Great video. No. A Fantastic Video. This should be shown to anyone with an aptitude and interest in science and critical thinking.
One of the best I’ve seen in a while.
With no preference of gender, racial or any other category. You either love this stuff or you don’t. You can teach it (force it down their throats) to people who are indifferent but that will be wasted effort. I’m 60 years old and I was glued to the screen to see the slo-mo video and hear your analysis.
Unfortunately, that is not what Public and most Private schools are promoting and teaching today.
Sorry for preaching but this is a great video.
Keep up the great work.
teachers should reference this video when teaching about forces, rotations, center of mass and so on in physics. Cool video indeed
Weight distribution changes with fuel exhaustion.
The firework is exhausting it's fuel from one end. So the heavy end is the opposite end. The rotation makes the firework spin like a top. By the time the rocket stands on the heavy end the firework starts jet from the heavy end changing from a top to a rocket.
Exactly what came to my mind when I saw the fuse burning through the glass.
Pretty much this. Also the rotation plays a non-negligible factor, but other comments sum that up pretty well
it is weighted heavy at the start I have ariel that is heavy at 1 end with side exit turns vertical then blades turning cause flight
This is what I was thinking too. Is the firework bottom heavy to start with? As the spin fuel is burnt, the centre of mass changes and the lighter end would lift.
To demonstrate the effect spin a cylinder full of clay and it will stay rotating on the same plane. Then spin a cylinder that has only been half filled with clay at one end and the cylinder and the lighter end should lift up if the rotational speed is high enough.
The thrust from the fuse hole being offset from both the radial axis and the initial centre of mass gives the tube enough momentum to spin. As the fuel is depleted the centre of mass moves away from the fuse hole thrust causing the tube to lift at the lighter end because as the centre of mass moves, the rotational axis moves with it. At some point the two axes of rotation meet and the tube is now aligned for the lifting charge to ignite.
@@maxximumb Oh of cause! Nice spot!
NightHawkInLight, I saw this before and fell upon this video again. This time I had a fresh look and studied your slow motion videos. One thing I noticed is that the fireworks burns at the top, making the unburned powder below. This heavier weight would tend to be at the bottom and the burning section at the top, like a plumb bob. Then the powder continues to burn and the flame hits the open core which exhausts out the bottom.
What's crazy, is that they are quite a complicated mechanism, but they are reliable albeit being made of crappy cardboard and clay. It should be an inspiration for rocket designers :p
nraynaud1 i wouldnt call it complicated, its a tube with a hole in the side and a plugged end full of black powder
@@Videoswithsoarin there is a *LOT* of physics and chemistry at work when it comes to fireworks.
even the very simple ones like firecrackers.
Imagine how dizzy the astronauts would get..........
Most rocket motors are already made out of cardboard and clay
Rather it's itself an inspiration from rocket science buddy ✌🏻
“That was a mouth full of words and every one of them might be wrong.”
😅
First time watching your videos and I am subscribing bc of that line. Doing the work to test the science and still admitting possibility of error! 👍
nighthawk does not put out a ton of videos but i believe he is one of the smartest people on the planet.
Watched the slow-mo footage and turns out I was right. It's all magic.
haha nice man your a pyro dude! i been making fireworks since the 80's! i would say that the bottom has more weight in clay then the top causing the "weeble wobble" effect. the fuel above is also a different composition then the rocket fuel used for lift. also the hole coming out of the side should be entering on a slight angle rather then just straight in but not sure.
Slow motion cameras,
Essential need for curious minds ! 😊
Thanks for sharing and take care. 👍
Dude, vid and footage is Amazing. The whole thing fluently speaks to my preferred style of learning. First you present a succinct, pithy hypotheses. Then make verbal statements supporting your hypothesis and then the best for last. You SHOW ME how your idea plays out clearly in slo mo. I love pyro and am grateful to you for sharing how things work. It’s a behind the curtain glimpse of how the wizardry of pyro magic happens. SALUTE
Maybe the bottom is heavier, that's why it aligns vertically?
an object, if allowed to rotate freely, will do so in the axis of least moment of inertia. MI directly propotional to radius. You are right, in this case keeping jet one eccentric to one side makes the other side heavier, which makes spinning on that side more stable (stable equilibrium) long enough for the second jet to fire.
Yeah but maybe like tippy top. It had its heavy side up!
Another interesting video, I too have found the mechanics behind these fascinating.
Very cool to see them in slow mo.
Flying fireworks were illegal where I grew up. We found a way around that as children that I never understood.
We found that if you lit then threw one of the "ground bloom" fireworks into the lake about 50% of the time they would fly out of the water similarly to these fireworks being demonstrated.
I would love to see a slow motion video of this phenomenon.
Thank you Ben for always doing a stellar job at explaining what you think is going on and ALWAYS being humble in the process, that alone speaks volumes as to what kind of man you are!👍👍😁😁
Interesting... I might know but am equally unsure... I remember being taught that objects only stably spin around axes of maximum and minimum moments of inertia. Books can spin flat like a frisbee about an axis perpendicular to the pages or side ways around an axis parallel to the spine (assuming portrait format) but cannot be stable end over end. This firework will only be stable spinning on its end as the maximum inertia is shared by two axes sideways through the cylinder. The off-centre thrust especially with ground effect can kick it to transition, as can friction at the bottom like the tippee-top. That’s my guess anyway:) great video
I was thinking the same thing and you explained it perfectly!
It's a variety of effects that give it it's properties like you said. The main one though is the gyroscopic precession like Euler's disk. And thank you for the slow motion on those, I wondered these things too.
“Which you should not do.” *nearly gets hit by firework*
Well then, he made that point well.
Doesn't matter how long it took you to figure it out be proud you think like that how the art works rather than just being simple and enjoying it
try it again on surfaces of varying friction coefficients!
They seem weighted towards the thruster end. Maybe you can follow up with a video where you show the center of gravity while it's laying on it's side. I don't know if you can use bamboo skewers to do that but that is what I would try. Awesome stuff as always! I'm binging your channel during the covid-19 shelter in place. Stay safe and thanks for the great content!
I think it tends to stand upright because the propellant burns from the fused end making it lighter in weight.
The bottom end must be where it is because it has still unburned propellant making it heavier.
But of course I'm only taking a guess......
@David Barr They aren't right though... There's a giant tunnel in the bottom half... That's way less material then a tiny fuse. Idk how you thought they could be right lmao
Torque. Torque points toward the fuse end. If the fuse was flipped around, it would point away.
@@SylasTheGreat a giant tunnel... through a piece of clay at the base. if you pause it at 3.00 and have a look at the clay on the top part of the bottom section (above the 'tunnel') you can see it angles towards the fuse hole ever so slightly, which I bet changes the centre of balance and spin axis ever so slightly, but probably just enough.
@@brapamaldi it's still lighter on the bottom so it still doesn't work
@@SylasTheGreat
How is it lighter on the bottom when ignition starts from the top where the fuse is?
The other thing to consider is centrifugal force and motion added to the mix.
@3:16 - AWESOME idea, and great execution. LOVE that visual.
This is very cool slow motion. (sad no ending bird clip)
love the way this way shot. really makes viewer think
I felt like a kid again! )))
p.s. Ben, if you want your brain to explode try to figure out a "Spinning T-handle in zero gravity" effect. There are videos on youtube showing this amazing effect (of t-handle spinning in the air and flipping back and forth at the same time).
Yes! 3 axes of rotation with different center of mass. It's cool & must see.
This is probably my favorite novelty firework. I just love the sound they make. I'd buy a box of them over ground blooms any day.
take the spinning top and record it. now play the footage backwards. that's how the rocket stands upright except rather than normal force it uses a pressurized jet of burning fuel
decelerating spinning top versus accelerating spinning rocket both changing angular momentum, transitioning from upright and spinning to laying down and not spinning or vice versa
tippy tops work on the same principle but are a different application of it.
To be honest, I think you hit the nail right on the head with that"really long mouthful of words...", That the friction from touching the ground, with the spinning motion creates a simple spinning top type effect, then a short burst from the tiny rocket engine that by necessity is pointing straight down and spinning, no tail needed. Thanks for the video, very interesting.
pls do a collaboration with the slow mo guys or smarter everyday to film even more impressif firework ignition from the inside with your glasplatt technic, it was awesome
god yes this
Love how you have your own disc golf cage in your back yard great way to practice the short game.
if this were kerbal space program I'd say it was gyroscopically stabilized. Spinning stuff goes straighter because it averages out. Handy in flight.
That half firework was pretty dope. First time I've seen that
I think if you watch regular ground bloom fireworks AND the helicopter version in slow motion, you'll be surprised! 😉
Yep i think so too
Omg thank you so much sir!! Now I understand how & why these little novelty fireworks work!
The cut away of the firework is amazing, it's so similar to solid rocket boosters used for spaceflight!
As usual a superb video !!
I was thinking of a way to test the ground effect....
Maybe you should try the same things you did in the video but on a metal mesh surface. It would allow must of the thrust to go through the surface, so the firework would maybe take longer to stand up right.
(the mesh might cause a friction problem ... )
I found it by looking at Ben on a Japanese TV show! Please do your best to make fireworks!
These are also my favorite fireworks thanks for the great footage of them and starting a discussion
It would be really great (technically difficult to achieve, of course) to see them go off in free air rather than close to the ground. I bet that would help unlock the effect of having that solid plane of the ground causing them to go up. Another idea is to set them off inside a half sphere and see if they tend to go up or more perpendicular to the surface of the bowl. The fact that the flat surface is perpendicular to gravity may be significant. Being able to observe them in freefall reduces or eliminates gravity. Angular momentum is definitely a factor. Changing center of gravity. Air resistance, perhaps even magnus effect to some degree. Probably even The Dzhanibekov Effect.
Initially I imagined it similar to a lemon, where you start spinning it on its side and its rotation translates to the adjacent axis and spins on its end. Then when you mentioned the tippe top I was even more convinced I was correct.
But seeing it in slo motion, it seems the side vent it slightly off center so it rolls around and is just pushed upright by the jet of exhaust.
Me: Sis what do you think? You figured it out?
Sis: It flies straight up because it does that's why.
Such wicked filming angles! Nice work!
Could try and make one of these for yourself? That would be something I would like to see.
When the firework's initial exhaust is pointed upwards or anywhere pointing up, it pushes the firework to the ground, but there's no downward movement due to the ground blocking it, but when it's pointing down, there's nothing holding against the firework on the upper part, therefore it's pushed upwards. When the firework is lifted up, the gyroscopic precession and other things play their part.
I’m refraining from reading the comments just to keep my thoughts trained on what my intuition was telling me, and I didn’t pick up on you mentioning anything about it: mass! Or rather, center of mass. I’m not a rocket expert, but a center of mass is crucial in getting right in rocketeering (thanks Destin!). I’m wondering if the burned fuel from the spinner nozzle end of the firework causes a shift in mass in such a way to force the firework upright while spinning. My guess is this would cause the center of mass more towards the large nozzle. I also think that there probably is some gyroscopic procession or however it’s spelled that helps exploit the shifting in weight to cause it to be upright. Maybe you could do an experiment that shows a spinning rod (with unsymmetrical distribution of weight to one side) while prone/horizontal, will want to stand up straight with heaviest part on the ground, and lighter upwards. Thanks for the video and for sharing the unsolved problem with others :)
My favorite firework I've ever seen used was dark turquoise blue and said SHAZAM in bright turquoise on the side.
Its size was about halfway between one of these and a stick of dynamite, and it was completely nuts.
In a crowd of people who loved fireworks and in North Dakota where the 4th of july is world war 3 every year, not a single person there had seen anything like it.
Somebody lit it, threw it out in the street, and it spun for a second before it sounded like a jet flew overhead and it shot straight up into the stratosphere and disappeared forever.
I've never been able to find one for sale or even in a youtube video ever since, and out of everyone there that day, we all only had the one.
A single firework that just totally bamboozled everybody and vanished from our lives forever.
note, patreon email telling me about this video had a bad link to the video. i had to go to patreon and then click on the video link there to get here.
This brought to mind two old youtube videos: "Spinning Tube Trick Explained" by Veratasium, and "Strange Spinning Tubes - Numberphile" by Numberphile. In that situation, the tube, despite not having a rocket on it, still lifts up a little off of the surface.
I thought exactly that this was going to happen no joke
That cut in half firework was oddly satisfying to watch in slow mo
Excellent video as usual. :-) Check out the desalinator I told you about, I just uploaded it.
I've never heard of these things before, but they're freaking amazing, that sound they make is straight out of a cartoon! XD
You really dont need to light them with a fricking blowtorch.
You sir have clearly never owned a blowtorch.
It's a lot faster and more reliable to use a blowtorch
@@gabedetter1570 Did you just assume my gender?
Kinda figured the thrust imparted rotation around it's length and it pushes of the ground standing it up then firing it's thrust. Figured it out before seeing slowmo :D. In the end you mentioned how it's not just the ground effect though and I believe you're correct. I think the off entered thrust corrects this. If you think about it the thrust will always have a larger radius when it is spinning at a tilt. Just a junior physics major, hope this helps.
I am looking at this as a spin balanced system very much like a spinning top, as you suggested . The side exhaust is pushing in all directions (with a slight angle to incur rotation), preventing it from falling in any one direction (would imagine speed of rotation is a factor) and once it is semi balanced the flame will simply push it up.
Okay the shot of the firework cut in half on the glass was soooooo freaking cool!! Awesome video!
Dude that shot of the motor cut in half was SO COOL
so the first fuse lights, it's positioned to make the tube spin. if the thrust of that gets close to the flat surface, it has something to push against other than the air. so more of the energy emitted is converted into thrust? this then pushes that end of the tube vertically, the spinning creates a gyroscopic effect too, so then it's vertical and semi-stable, it kicks on it's main thrusters! i really love the part when you cut one in half and stuck it on some glass, that looked really cool!
Keeping the glass crack in the slow mo shot excited me way too much 😂
I burned some magnesium in a glass ashtray once and it cracked/exploded.
This video makes me remember Mythbusters because your high-speed shots are so perfect.Well done man
Ahahahaha, i knew it! That slowmo footage got me so excited to see it and confirm my theory. I didnt know how to explain it but i imagined it in my head the same way it was shown, and it made me so happy to see. i love this cannel
fascinating! I love how you go back to figure out something puzzling you way back in childhood.
I think high speed cameras were invented to frame fireworks, and I love it !
I played with this kind of firework when younger, I had some with two holes on either side of the cylinder, one up and one facing down. The firecrackers flew systematically but only by rotation, it was not a propulsion.
I never found them again later.
You should tear one down, remove the fuel, then try and build an enclosing case of your own. Maybe you can design different cases to see how it affects the spin and flight path. I really loved watching this and appreciated the slow-mo sound fx. XD
Love the disc golf basket in the background. Nice touch. You also need to take into consideration manufacturing defects or variances in chemical make up. They are cracking these thing put pretty fast. The nozzle geometry could be different from one to the other. Just my two cents. Love your videos always so informative and thought-provoking.
Ground effect + spin stabilization for the win.
Nice video. I love these things. They spin so fast they sound like a dremel or air tool. Was hoping you would give us the rpms...
I love that glass crack. Slow-mo of it was beautiful
I must have gone through 1000s of those as a kid. Cool to see how it all worked. - the cut in half glass shots are awesome. (It’s also heavier at the bottom because of the clay and unburned fuel so that may be why it stands on end as the exhaust pushes it up a bit?)
You should refer to some of the (many) videos on the "Intermediate Axis Theorem"
This is why the thing stands up and spins. The math is a pita, but it boils down to having a positive feedback whenever there is a deviation on the less-stable axis.
I can tell the internet is wearing down on you.
Intelligence doesn't hold a flame to curiosity and willingness to follow the scientific method. I always appreciate watching your videos. You do great work.
l loved that glass cracking sound effect
I loved those zips fireworks!
This slow motion footage is so cool
These fireworks were some of my favorites the speed & sound they make is so cool and they were cheap.
I think you got it. I just found those things last 4th of july, been trying to figure them out ever since. All I needed was your high speed camera, thanks.
theory : the cylinder is initially bottom heavy because of quantity or/and type of the second stage propellant.So, while the first stage burns and the stabilizing spin initiates even more propellant is burnt from the first stage /top and therefore when the time comes for the second ,still heavy ,stage to ignite the whole thing has balanced/righted itself on the vertical axis and off it goes . Nice videos as always !
Love the cutaway view of the firework!!!
Thank you for your great documents, wish I could watch these when I was in school, but that would have been in the 60`s.
What an AWESOME video😍😧👍 and 1:06 when VTech kicks in xD
Extra thumbs up for the disc golf basket!
Seems pretty simple. The hole at the side ignites, and it starts rotating. Once it intersects ground once, the momentum kicks it up and further spinning occurs, when the initial charge pierces into the main tube, the mini stabilized rocked pop up. Ingenious and simple.
I'm pretty sure it has to do with the way the hole is drilled in the body. Is it offset from the center axis towards the chamber?
ok, my guess is.....
the exit hole is not only tangential to it length but as you also pointed out tangentially to its axis. this creates a spin in 2 axis. one of those spins is high energy, axially, and one of those spins, along its length, is low energy and used to help start a gyroscopic procession so that the point of contact will shift as friction grabs hold. because of the spin tangential to the axis it also rotates and when the jet is blowing into air it only has so much mass to push against (and/or is just pushing down in with gravity) but when it rotates about and faces down it has the "ground effect" or something to push against (and/or is blowing in a direction not forcing the body against a solid surface) which starts to stand it up. when it stands up you develop the friction point along its annular face which combines the low energy spin and high energy spin combine to finish standing it up. think 'spins faster, when the procession wants to bring the axis of rotation over the friction point as the friction point is brought under the axis of rotation. because the speed of rotation is increasing as force is continued to be exerted you see the gyroscopic procession work backwards then you are used to seeing (as it gets slower it processes more is now happening in reverse. gyroscopic recession?) this brings the body to line up in a direction mostly up when the launch charge ignites, and, as its still spinning while being launched you now have a rifling effect to stabilize it in flight and through doppler effects and hiding or exposing the noise source on the front or rear side of the body as you view it you get the warbling effect in the sound.
5:24 the first thing I thought was "top". Then the super slow mo and you could see the jet pushing off the ground and starting the uprighting process. Have you measured the angle of the side jet (possible up or down angle besides somewhat tangential - wrong word I'm sure)? Is the bottom half weighted at all?
Love your videos and how you explain your thinking and process.
THANK YOU THANK YOU I LOVED IT!! It is so fascinating in SloMo TO SEE how the little stinker (pun intended) orients itself to prep for the launch!! AND, DID I MENTION I LOVED THIS VIDEO!! KEEP UP THE GOOD WORK!!
So glad you're still making videos ❤️
I think you're on the right track with the friction idea. I used to take batteries and marker lids and such and spin them on the table. What you do is lay ir flat on the table and put your finger on one of the ends. Then you press down hard until it pops out from under your finger with a great deal of spin. It will shoot out and away until you perfect the pulldown and back method. but you'll see it does the exact same thing as these fireworks. It shoots out spinning on its long axis and quickly stands up but then drops back to riding on just the bottom edge of the battery until it loses all of its momentum and stops. Try it yourself. Film it in highspeed even. You'll see it spins up and stands up just like your fireworks only with no thrust from black powder.
I would assume the distribution of the fuel also distributes the weight. The first burn rotates on its axis vertically because it’s mass is decreasing while the second lot of fuel still has all its weight at the bottom.