HOLDING AN EXPLOSION at 20,000 fps – Smarter Every Day 156

HOLDING AN EXPLOSION at 20,000 fps – Smarter Every Day 156


Hey, it’s me Destin. Welcome back to Smarter Every Day (SED). So excited about this video In the last episode of SED I showed you my transparent potato gun, at 3,000 fps during the day. 3, 2, 1 But this episode it’s going to be the same transparent potato gun, meaning we can look directly into the science at night, at 20,000 fps. Google up! Science is about to happen. What happens, if I start the ignition of the potato gun from the back? vs. What happens, if I start it from the middle? I always thought it would have worked better if you go from the middle, ’cause you get even expansion of those gases. But, let’s record it in high-speed, and let’s see what the difference is, between the two. We’ll go from the back first! We got some potato juices in there. 3, 2, 1 (laughter) It’s like 9 o’clock. Alright, let’s see it in high-speed. It’s completely awesome. We saw that it started at one end and went all the way to the end. Now, I’m gonna take this, it’s a grill-ignitor, You can see the little zaps there. I’ve got electrodes, set up in the center of the potato gun and we’re going to zap it from the center and we should get a more even combustion, right? So, let me hook it up and then we’ll give it a shot. literally. Loading the potato gun again. 3, 2, 1 (laughter) It doesn’t get old! Was that cool, or what? Ok, so check it out, so this is my combustion chamber, right? The first time I shot this thing, it was a flint-sparker on the end of this thing, right? If I hold it, you can see a twist and I get the spark. What you saw on the second time – here are my electrodes that I told you about going to hit this button you can see
down in there. Can you see what I’m sparking right there in the middle? That’s how I fired that thing. When we
first start the combustion from the end it’s a wave you’ve got an oxygen/fuel mixture that
goes all the way down to the combustion chamber; when we start right in the
middle, we start to expand, we start using that
fuel and using that oxygen, but we run out of oxygen before we burn all the
fuel. We’re going to shoot this thing from the end, we’re going to zoom in with
a high-speed directly on the combustion chamber and we’re gonna see if we can
see that flame front moving one Mississippi two Mississippi three
Mississippi four Mississippi three two one Ok, before i show you the next slow mo, I
want you to understand that it has enough information in it to provide for
several phd’s ,so I want you to be on the lookout for a couple of key things that
I find interesting. #1 When the explosion moves
towards the closed off into the combustion chamber, unless the fuel/air
mixture is just perfect, sometimes you’ll run out of oxygen and
have unburned fuel this creates a compressed pocket of fuel,
that stays unburned until it turns into a rarefaction and pulls more oxygen back
in through the barrel, to burn it up #2 There’s something that
happens in combustion chambers called “sidewall cooling” basically the pipe
itself cools the gases down below the combustion point, so it can’t burn right next
to the wall this leaves more unburned fuel and
actually counts for most of the pollution products caused by the engine
in your car The slow-motion you’re about to see is
real. I haven’t ran the speed, to make it look more interesting, It’s just pure awesome footage. Straight
out of a high-speed cameras. Watch what happens, as the explosion over
expands, the system has to equalize so it pulls air back in through the barrel
,into the combustion chamber, which causes that fresh oxygen in the air to meet up
with the remaining fuel and start the burning process all over again. It’s a pretty inefficient way to burn a
fuel rich mixture; so I think my original hypothesis might
be wrong. I think it’s cool that when the gas
squeezes down into the barrel from the combustion chamber, it has to speed up so
that it can maintain the exact same flow rate One of the things I love about science,
is the ability to look at a complex dynamic system like this and try to
understand every physical phenomenon that’s occurring, but equally important to
me personally is the ability to look at footage like this and say “you know,
that’s pretty.” To summarize, what we’ve learned tonight,
think about this: when you have a combustion chamber we’ve learned that it depends not only
on the localized chemistry or the stoichiometry, the fuel/air mixture at
any point inside that combustion chamber; it also depends on how its vented it’s
really fascinating the dynamics of venting a combustion chamber effect
directly the ability to create localized pressures and rarefactions sometimes at
the end of the video when the add part comes up you kind of roll your eyes ,because
you’re not excited about it. Well, this time is different, you see,
SED is supported by audible.com and they have supported me for a
really long time and it’s a really big deal because it’s kind of expensive to afford videos like this. So, what I’m going to do is I’m going to
create an audible event so that you can remember to support SED at
audible.com/smarter. We’re going to create the same flame
front that we did before, only we’re not going to contain both sides of it we’re
going to vent one side I want you to listen to this huge
audible vent and then we’ll look at high speed ready? 3, 2, 1… It’s on fire! If you want to support SED,
feel free to go to audible.com/smarter. That’s a very audible event, I hope you
agree, anyway they have tons of free audio books.If you get a free trial at
audible.com/smarter I’m super stoked that they have chosen
to support smarter every day for so long they’ve been a very valuable partner and
I am very appreciative so if you want to support SED directly go to
audible.com/smarter get a free trial of audiobooks you’re going to get
smarter and you’re going to like it. So there you go, I hope you feel like
this video on your subscription if not that’s it. I’m Destin you’re getting smarter every
day have a good one (inaudible) i … going at
watermelons. Yeah and I’m record in slow motion You are? Yeah. Is that cool? – That’s what they all say…
You don’t do it at night too? Is that all right? – It’s your property, do
what you want to do on it. You do anything you want to do over here! You ain’t going to bother
me I think it’s time to go to bed


100 thoughts on “HOLDING AN EXPLOSION at 20,000 fps – Smarter Every Day 156

  1. At about 6:15, does the gas speed up to maintain the same flow rate or is it due to the Venturi there and or the immediate cooling of the gas met by “cooler, fresh” oxygen?

  2. in the philippines we make that kind of cannons as alternative for fireworks and explosives during new year. Usually me make it from cans or bambooos or pvc pipes

  3. I am willing to bet that you have BEEN "witHOLDING AN EXPLOSION far greater than 20,000 fps – for ever"! If and when you ever get laid your load is going to damage some guys intestinal track up bad!

  4. I’d love to see some experiments with injecting nitrous oxide and other oxidizers at different times after ignition. More boom, please!

  5. So i was watching this and everything you said was interesting but i want to ask what the glowing streaks were in the finals stages of combustion? The best example i saw was at 6:00 minutes.

  6. You're chamber is set up incorrectly, it should burn all the fuel and you should only need a small spray of your fuel.

  7. at 5:31 to 5:35 as the second explosion is happening,
    in the center of the explosion,
    is that electricity from the rods being pushed off by the force?

  8. I like how you simultaneously explained it was the ad portion, described what you were doing, and rushed (safely) to keep your audience around.

    No loss of flow. Just a little extra speed at the end

  9. Hey destin I've been watching your videos for years and I rewatch your videos because they are that amazing but this is my first comment……like ever….but my question is in the high footage what is that really bright glow in the center of the flame and as the flame leaves the chamber I believe that it happens both ways of lighting it but the weird thing is is that as the flame leaves the chamber the very bright points of light as they leave there's a trailing effect you can really see it at the last up close footage of you holding it while firing I'd love for you to do a follow up video on this effect

  10. I don't know if you noticed it but that potato starts moving sooner and faster with the ignition taking place at the end rather than the middle.
    And I'm sure your neighbors are used to loud noises in the night. 😉

  11. And cool video, not a good idea looking into the barrel right after a shot, like looking directly into a damaged tire valve stem guts, even undamaged unless there's no air in the tire. How about a slow motion close up of sparks off a battery charger or a spark plug looking at what 1 individual volt(a bunch of electrons) appears like

  12. What I noticed, is that the Fuel, when started from the center, was influenced by Gravity, it started it's burn from just above the midpoint and worked it's way to the Top. This makes me think that a standard model for a Cars engine, might be more efficient if it were upside down, allowing the ignition point to begin at what would be the Top of the Cylinder, making the Combustion more efficient and burning more of the Fuel.
    Just a thought……

  13. Nice! I use static guard to ignite mine it doesn't leave a sticky film behind or make the end cap stick like hairspray does!

  14. A couple come home from a night out. "Honey. Why is our window smashed and why is our lounge room covered in f**king potatoes?"

  15. you should Have Tryed To put the Potato underhalf way the Barrel. then fill up with gas. then Press the potato all the way down. Would that do Any Difference O.o you know because its Under pressure

  16. 20000 feet per second is extremely unlikely considering that the 50 BMG is only moving at around four thousand feet per second… but still an awesome video.

  17. How about multi-point ignition, specifically; 3 parallel circuit electrodes at 5, 50 and 95% chamber length. May be a more efficient combustion process. Maybe overpressure.

  18. 7.30
    You can pause on the flame when it shoots out and you'll get nice clear snaps of it.
    Doesn't match with the fake graphic enhanced animation at the end.
    I don't understand why you'd put up misleading content which can be easily fact checked.

  19. The last one I made I was shooting tennis balls about 1/4 mile. I put a T at the top of blast camber with bbq lighter in top and the T doubles as handle. Then in back of blast chamber I put a metal valve stem from a truck wheel. Spray starting fluid in for about 6-7 seconds then put air compressor on stem till you hear ball start to slide. Then hit the ignitor. Boom mahahahahaha

  20. I've been watching for awhile. I'm a auto technician and your videos are always refreshing to watch. Nothing but problem solving and learning. If you only knew how good of a mechanic you would be

  21. I would love to see the shot with some 'debris' like spaghetti wire or nails in the chamber. The chaotic geometry is supposed to speed of the flamefront a lot.

  22. Have you put oxyhydrogen/HHO Gas from electrolysis into the chamber. The ignition rate is much faster and burns 100% completely because it burns at 44,000 ft./s I have made a cannon that shoots rubber balls 300 feet into the air with very small amounts of oxyhydrogen gas. That would be using 1/3 of your chamber.

  23. 0:51 I live in the country, the neighbors would think i am out shooting my cows. yup they are psychos. But do that in the cites i think it is a call down to the Sheriffs office.

  24. So flipping cool I can't stand it. I love that the mid barrel ignition makes the fuel burn multiple times. It's like the tube is breathing. There's just so much to see. I could probably watch this dozens of times and still notice something new. You provide an incredible service to people through your videos. Thanks for being awesome!

  25. Did I miss the word "propagation"?
    The ignition of any firearm should begin at the rear of the fuel/charge creating a burning and continually pressure wave that propagates forward accelerating the projectile to the maximum possible velocity.
    By igniting it in the center half of the pressure wave is headed the wrong way, at least initally until it hits the rear cap (with arguably much more force than it would if ignition began at the cap).
    Also, by drilling two holes in the center of the chamber like that you've compromised its burst limits.. I'd throw that mess away before it rips your stomach open.
    With a cap failure it simply blows out the back, harmlessly, as it should. (which is why the flint igniter is a bad idea too with a hand/fingers in the way)

  26. Using two different types of ignition sources kind of adds a variable that can skew your results.. am I wrong? I made a tater Cannon using the guts from a 800000 volt taser and let me tell you, it is violent! I have plans to make one out of copper tubing that uses an oxy acetylene mix as my fuel and a 1 million volt taser as my ignition… if I don't die, maybe I'll send you the video.. P.S. the tighter your projectile fits in the barrel, the higher muzzle velocities you will achieve. So I stopped using potatoes and started using those little rubber feet that are on the bottom of those walkers that old people use..the combustion makes them expand just like a pellet in an air rifle. Also u can put washers inside of them for a more forward c.o.g. and to add weight.

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