It's called a "Bernoulli Pump" and we used them in the Navy to multiply the volume of water that our pumps could move, for about the same power. A stream of moving fluid (air being a fluid here) tends to draw surrounding fluid along with it. the air is compressed and pressurized by the plunger, pushing it against the primed dart, and the release is the air rebounding like a spring let free: equal and opposite reaction means the launcher and the dart air pushed away from each-other. upon release; the air is high pressure at the face of the plunger and the rear face of the forward dart, but it's motion in the middle is suddenly flipped to low pressure. (until equilibrium is reach based on the mass of the air, if your barrel were long enough and the system were sealed, you could stop the dart dead in the tube as the air is "stretched", until it's density (and thus, pressure) is too low: making a vacuum force where atmospheric pressure is pushing the dart into the blaster, rather than out.) (this flip commences from about the middle of the mass of the compressed air, and radiates outward rapidly) the low pressure of the moving air "sucks" (rather, the higher pressure of ambient air is pushing) the dart forward. If you ran constant air through it with a compressor air tank, you could continuously feed darts into it without having to feed them all the way in front of the moving air: the Bernoulli Effect would draw them forward into the moving stream of air. EDIT: spelling
"If you ran constant air through it with a compressor air tank, you could continuously feed darts into it without having to feed them all the way in front of the moving air" Sounds to me like Matt needs to look into a fully automatic nerf air-tank-powered blaster now!
So are you saying the plunger system is not necessary, and it can be replaced with a compressor or that the plunger system can have the air compressor feed darts as it recocks without pulling air ?
im loving all of these stupid simple solutions to things, like putting water on the dowels to make them expand. The blaster's design is also pretty awesome
Gotta admit, the dart head as a dampener is pretty smart. Love your ideas, may not be good for quick firing, but they work and its goofy yet useable and reliable.
Holy cow, this channel's production quality has skyrocketed since I first subbed. Great to see the work you continue to put into making these projects!
The reason why the dart is pulled by the action is probably the same reason behind a "vacuum ejector", the movement of a higher pressure air passing through a channel can create a vacuum.
Honestly, probably the best "build explanation" section I've seen out of any of the building channels I watch, because you went step by step on everything and explained how you did pretty much every little section, while most building channels tend to just cover the key points.
I have recently begun building my own homemades (following nerfhaven guides) and I am inspired by your precision and ingenuity. They make me want to bring another level of polish to my blasters :) keep up the great work!
Dude you are such an awesome channel! It’s fascinating watching you build these and all the unique techniques you use, like just adding water to expand the wood, I’d have never thought of that.
To test if it’s a drop in air pressure in the barrel is what moves the dart forward, you could test using shorter barrels so that there is still pressurized air when the dart leaves the barrel.
I think the key moment for the back dart is when the front dart exits the barrel. The higher pressure air is then connected to the outside atmosphere, which sucks it forward, which in turn propels the back dart as a temporary low pressure region is created behind the air wave escaping the barrel.
The reason i think the dark that is loaded moves up into the chamber is due to a vacuum being formed. As the first dart ejects out of the barrel it creates a tugging force or vacuum, and the other dart wants to move to help reduce the vacuum as the air on the other side wants to get in. But once the first dart leaves the barrel the vacuum dissipates as air rushes into the barrel of the gun. leaving the second dart ready to to fire.
I think that effect is the same principle as fluid hammer ('water hammer') Though the net pressure never drops below atmosphere, gas movement has an inertia that creates a vacuum when the plunger suddenly stops. This similar in principle to the Venturi effect, though the configuration likely means it is not truly Venturi
The sealing dart could be being pulled along with the air after the fired dart leaves the barrel, the excess air rushing past with less resistance might be able to pull the back dart forwards. the lower pressure idea makes sense as well though, might be worth making a test breech with pressure gauges to see what's happening.
Dude, I gotta say your fabrication techniques are really smart. By the 5 minute mark I had learned 3 new things for fabrication. Heve you ever thought of doing a series on fabrication?
Love this kind of content. I'm trying to remake my nerf collection after mom sold it (without my consent). I might just start building my own blasters!
What probably happens to the dart is that it gets sucked in, and then the opening behind it gives an easier way for air to release pressure through the back as soon as the dart passes the hole
Bernoulli's principle is probably drawing the second dart forward. You can check by loading just one dart and providing a constant stream of air through the barrel.
Oh, that is so cool! My initial thoughts on how this might work led me to a different idea... -plunger pulls from front to back -Muzzle is capped with a moving cover -Pull a vacuum in front of the dart and put the pressure behind it -when the plunger bottoms out (or some threshold is hit) open the muzzle cover basically a combination pressure and vacuum cannon. Hmmmmmmm
I think maybe the air is grabbing the holes in the head of the dart, which pulls it forward. You might be able to test that by getting half-length darts with a solid tip (or just cutting regular Nerf darts in half) and see if there's any difference.
I totally thought this was going to be a venturi effect type thing and I imagine that's what pulls the second dart forward, reduced by the fact the othsr dart raises the pressure.
The air traveling out the barrel has momentum it lowers the pressure at the rear enough to have the outside pressure apply a small force to the second dart. You can look at different ways to measure any reward force to disprove the compression/bounce theory. You can also look at building other seals around the rear of the beach that would help prove the greater air pressure behind the dart or just directly pressure ahead of the breach.
I'm probably never going to build a Nerf blaster in particular but i really like the construction techniques you used, i will adopt some of them. If i don't forget.
Cool video as always! I wonder if you've ever considered making a "shell" or "cover" for one of these completed projects to go around the components to give it that finished Nerf blaster look, just for fun.
There is a good chance that the rushing air drags the dart a bit. It can also be that after the dart is released that the moment it leaves the barrel the pressure for a second is flushed out by momentum which in turn creates a temporary low pressure zone until the atmosphere refills that area. Hell, it could also just be the intial kick and the dart collides with the plastic lock and the foams elasticity knocks it forward. More data is needed.
9:55 the awnser to your confusion is suction and yes there is suction created while blowing in a 3 way tube even if it only goes one direction it will create suction on the 3rd hole that was an old old way to create a vacuum
I think you could get a cleaner slot in the barrel using an end mill in the drill press and clamping the tube to the aluminum, then just sliding the aluminum back and forth. It would get rid of those wavy edges and allow for more consistency in slot with, while also taking less time and precision.
Similar to the Venturi effect, when the air pushes the first dart through the barrel, as the rear dart is not a perfect seal, it will draw that along for a moment as the high speed air passes by. Similar to how a Dyson bladeless fan works. (or a venturi oxygen mask for the old as hell current/former emergency healthcare peeps)
I think what happening is the dart in front is a projectile while the rear dart is the rear seal of the barrel, and when the front dart moves the rear dart acts similar to a air restrictor, because there is a small vacuum on the head of the dart, causing the outside air pressure to push the rear dart forward.
Wow. These nerf blasters are getting better and better. You should try making a nerf blaster machine gun that can be set up on your car or something. Maybe even add a place where you can sit to control it by hand instead of remote control
How did you come up with the idea for the brown jig to mark the spots to drill out the pump grip slot? Did you see it somewhere else or did you have to come up with it in your own
interesting design, it reminds me a bit of those lever repeaters, the design could certainly use some improvements though, best of luck! btw I'm still kind of mad that you didn't violate physics.
Do you post files anywhere? I love scavenger-type blasters and this is super clean. Combine the single-chamber with an inline/RSCB clip and you’d have more loaded capacity, though IME single loading is plenty effective.
If there's negative pressure in the barrel, than it might be a good idea to try and use a shorter one to check for that. After all, negative pressure in the barrel would indicate that the projectile is also being pulled backwards midway, so changing it out for the future blaster might be a good idea if that's the case
I'd try shorter barrel lengths, to see if the rear dart still gets sucked forwards, that vacuum effect might be a hint at lost velocity if it's helping pull the rear one at all right at the end. That or it's an impulse due to equalizations, that might be prone to happen regardless of barrel length. Does this also happen if you mount it in a vice or rest the lower tube against a table and shoot over it? Plunger slaps the gun, paddle on the blaster slaps the dart. Those are my possible theories.
