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
Fuck, this is mesmerizing...
That is honestly some of the most beautiful slow motion I've ever seen, Destin. Never would have thought that the explosions would be so smooth looking... Makes me think of my own potato cannon a bit differently. It was also super cool to see the oxygen being drawn into the chamber after the potato left the barrel!
Thanks for another great video.
I think everyone would love to have a cool neighbor like that guy at the end of the video...
"Hey, I'm gonna be shooting this really loud thing while you're in bed"
"You do anything you wanna do, you ain't gonna bother me"
Brings to mind this hybrid rocket engine made out of a transparent acrylic pipe and gaseous oxygen: https://www.youtube.com/watch?v=TLPWqCMb7DE
I now have a strong desire to make a potato gun.
And eat french fries.
I hope to one day love something as much as this guy loves his potato gun hahaha
When I was in HS myself and a couple of friends built a potato gun. Barbecue ignition and a good-sized chamber. We took it a few miles outside of town into the desert and we were launching potatoes and having a great time. Then a cop car pulls up and we're scared shitless. Cops get out and walk towards us. There's no hiding this thing as it was almost as tall as we were.
Umm
We were just testing out this potato gun we built......
[Cops look at each other]
[Looks back at us]
We fired off a couple of potatoes and they were excited as all hell. Told us to keep it outside the city or else we'd be in trouble. Pretty awesome story. Makes me feel old as fuck to think, "back in my day the cops wouldn't treat you like a terrorist for shooting potatoes".
Edit: Just a tip for those who will build one after this. Not sure if it's in the video but aerosol deodorant is much better than hairspray. No sticky residue that glues the chamber shut and it smells a bit better.
Man I love that guy. I mean, man, I love you /u/MrPennywhistle...
And not in a, "I watched while you slept on my couch" sort of way. Although, you do this thing with your nose that is soooooooo cute when you're sleeping.
Come back to BC. Lets do more stuff!
Point it at a plate and bam! Instant baked potatoes