6 replies to this topic

[Azrael0987]

I'm currently working on a design in my head for a relatively small but decently powerful air blaster. I'd like to use an expanded hornet tank, and integrate that into the overall blaster design itself.



In the design shown in the picture (it was done at school with no access to shmee's writeup so that's why the Tee and tank part is a little off) the air input from the pump would go directly into the tank itself, and not through the rear air input of the hornet tank. Would that cause the tank to not seal properly? Backpressure tanks use the first pump to push the piston forward and begin to fill the tank. So before I start on this design I want to make sure it's not flawed to begin with. I did start thinking up this design after seeing Venom's venomaxx, so maybe he can shed some insight on the matter.

Any help or answers would be appreciated.

[Drev]

I am pretty close to finishing my blaster with a hornet tank expansion. Mine was based after the one that Ahtanie did. Sadly, that writeup is gone, but hopefully I can explain it. What I did was fit the back half of the tank into 1" PVC and drilled holes in the back of the hornet tank. Then I glued some vinyl tubing to the air input of the tank. After that, I put an end cap onto the other end of the PVC and drilled a hole in it to run the tubing through the back. I will have a picture up once I get home later today. Everything was solvent welded together to make sure no air leaked. Also, I used some JB weld to be safe. As for the air input problem, I think it has to go into the back. I'm not positive, so don't hold me to it, but it seems like it is the easiest way to do it too. I think Venom used a method similar to the one I that I used because he puts the tank in another piece of bigger PVC. This isn't confirmed, but it is my best guess.

[TantumBull]

The seal seats when air from the back pushes it forward, in my limited understanding. I actually have an expanded hornet tank lying around somewhere, I could probably throw on a barbed fitting and try it if you'd like. Or you could do the same yourself with a spare hornet tank, it need not be expanded to test this. Is there a real reason you need to pressurize it from the side? If not then why bother.

[Azrael0987]

It was only an initial design I thought up, so i'm not set on it. I realized it may not work and didn't want to finalize it then have to start over. In that case I'll change the design. Im thinking expanding the way schmee did it, then connect that down to snap on tee that holds the pump. Then just routing some tubing into the rear of the tank as normal. It would also be an easy way to make a handle for the blaster this way.

[Majestic]

As a modder who deals almost exclusively in back-pressure tanks, I would suggest that if you fill the tank from anywhere but the original input on the back the piston will not be able to move forward to seal the outlet. Also if you add a tank expansion to far rearward on the tank, all of the air in the prime chamber will not be able to escape before the air in the main chamber starts to escape. This will lead to reduced ranges. There is a discussion of some of the phenomena complete with diagrams to be found here.

[Azrael0987]

Thanks for the great information everybody. I'll work on the second design and let you all know how it goes. It may be a few weeks with school and other things keeping me busy, but im hoping it turns out well.