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Aeolus's Trident- MAJOR UPDATE! 11/26/2010

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Aeolus's Trident- MAJOR UPDATE! 11/26/2010

Unread postAuthor: saefroch » Mon Aug 30, 2010 11:37 am

I have been slowly becoming more and more dissatisfied with my previous pneumatic model. The most significant issue that I had with the previous build was its sheer size (which lead to a host of other problems). Thus the Trident (technically renamed Aeolus's Trident to differentiate from the Trident Antenna Launcher).

Specs:
Valve: Barrel-sealing piston valve (now with internal check valve)
Piston check valve cracking pressure: 5.4psi
Barrel: 0.364” x 18” (now 0.364" x 36")
Chamber volume: 5.38 in3
C:B ratio: 3 (now 1.5)
Port diameter: ~0.364"
Max operating pressure: ~2,000psi
GGDT muzzle velocity prediction @ 1,000psi: 912fps

The main purpose of the Trident is a test facility (and entertainment :D). I originally planned to experiment with different piston designs, but later concluded by simulations in GGDT that no design will have any appreciable benefit over the UHMWPE-based check valved piston it currently uses. The Trident is extremely portable, and has a very small chamber volume, actually 1.4 times the displacement of the second stage on my pump. Future plans for the Trident include evolution into a QDV hybrid. Due to lack of funds and design flaws in current QDV hybrids, development has been delayed somewhat.

The original piston design for the Trident was simply a solid steel piston with an o-ring firmly attached to the front as a sealing face. Unfortunately, the steel rod I used was significantly less than .5" in diameter, so I wrapped it in scotch tape to minimize the size of the equalizer hole. After two shots, the scotch tape had to be replaced. Not the best system. Check-valved piston made from UHMWPE with a very durable o-ring as the sealing face, and the back drilled out as the housing with a button-head bolt to form the housing for the check valve.

08/25/2010: Design is functional, now working on moving my piston stop forward, decreasing pilot volume and preventing the front of the piston from catching and shearing off on opening.
8/29/2010: Tested to 160 psi. Piston now seals at 40 psi, added a bumper to prevent damage to the piston, and reduced pilot volume.
8/30/2010: Completely leak-free up to 160 psi.
9/1/2010: First damage shots. Need something that's stable. Will be looking into ball bearings, slugs, and darts.
9/6/2010: Work on pump delayed :evil: Did some experimenting with GGDT... and it predicts no muzzle velocity increase with a UHMWPE piston having 1/8th the mass of the solid steel one I'm currently using. :roll: Gonna try anyway when I get my hands on materials.
10/17/2010: Parts ordered and shipping. Pump should be operational within the week. Expect much higher pressures and lower piston densities.
11/06/2010: Currently working on incorporating a check valve into the piston. Hopefully that'll be finished within a week and I'll have an almost maintenance-free design.
11/20/2010: Check-valved piston almost finished. The rear seal seal fits a bit tight into the valve housing so it's kinda like stuck right now. Plus I discovered today that my gauge somehow broke itself while not in use. :evil:
11/27/2010: Tensile strength of UHMWPE is terrible. By the time I'm done the piston will probably be mostly steel again. :roll:
11/28/2010: Piston very much improved. No problems up to 650psi, no replacement gauge yet so I dare not push farther.
11/29/2010: IT WORKS!!!!!!!!!

Damage at 1,000psi vs 1/16th steel plate. Amazed it didn't go through, but it was directly against the backstop(pre-check-valve).
Image

MASSIVE UPDATE
Check-valved piston (old pictures of the failed design have been replaced):
Image
Image
The piston was extensively modified from the original design and build, due to the terrible tensile strength of UHMWPE and its tendency to be extruded through an o-ring.

Shorter piston travel (I went to re-take this picture then realized my scope is in the way :roll:):
Image

Quick-disconnect rotated, stock modified to actually be effective, 3' instead of 18" barrel, and 4x scope (The bend is a result of some crookedly machined threads, I'll hopefully be replacing the crookedly threaded part with the next McMaster order.) I rotate the stock 1/4 turn clockwise for operation, it's just set like that so it can be filled:
Image
Image

What I did to be able to film that. The trident is sitting in for the camera... which doesn't like the lighting. Couldn't get a clear photo, since it was focusing on the ladder.
Image

Most impressive picture is of the first can, other pictures available on request :wink:.
Image

Finally penetrated the steel plate, at point-blank range with a deck nail
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Videos compiled to one, will be updated with progress:
[youtube]http://www.youtube.com/watch?v=t11363SkEU4[/youtube]
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Last edited by saefroch on Fri Apr 01, 2011 8:44 pm, edited 35 times in total.
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Unread postAuthor: Labtecpower » Mon Aug 30, 2010 12:25 pm

Very clean cannon, nice!
I dont know if you have the optimal C:B ratio, maybe you could optimise it with GGDT, as I think it's way too short.

Any damage pics coming soon ?
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Unread postAuthor: saefroch » Mon Aug 30, 2010 1:28 pm

Saefroch wrote: The main purpose of the Trident is a test facility. I plan to use the small size of the valve to my advantage; I am now able to use a .6” drill press chuck to machine pistons from various materials.

I still have the 3ft long barrel used on my other cannon in the basement, which I may stick on there after I'm done experimenting with pistons, but for now the C:B ratio is of relatively little concern to me.

Preliminary damage pics will appear when I can get something good to shoot. I'll probably be making some sort dart or "bullet" out of steel scrap.
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Last edited by saefroch on Mon Sep 06, 2010 8:12 am, edited 1 time in total.
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Unread postAuthor: Gun Freak » Mon Aug 30, 2010 4:42 pm

Looks awsome and clean, I like the piston, it is a good idea. How often does the seal blow out? Also I think somebody beat you to the name Trident. It is a hunk of DWV of a cannon that PCGUY posted a while back.
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Unread postAuthor: saefroch » Mon Aug 30, 2010 4:48 pm

How often does the seal blow out? Not yet. It might come off if I get to 500 psi, but it's very firmly attached right now. The McMaster-Carr item # is 5308T247. I used a clamp and screwdriver to force the o-ring onto the piston.

Darn, guess I'll have to change the name. Everyone's been calling it a trident, so it'll just have to be some variation on that.
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Unread postAuthor: Lockednloaded » Mon Aug 30, 2010 4:57 pm

keep the name it fits. I like the layout, but do you plan on getting an hp setup to push it to its limits
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Unread postAuthor: saefroch » Mon Aug 30, 2010 5:58 pm

Saefroch wrote:very small chamber volume, actually 1.4 times the displacement of the pump I am (still) working on (and shouldn’t be for much longer).


I broke my pump a while back and started on this project. At that point I had only pushed the pump to 360 psi. I predict with my weight that I can reach 680 psi, and my predicted dead volume should only limit me to 1,100 psi. A thread will be posted when the pump is finished. I know that I can exert 170% of my weight in force against a pump already, so who knows how high I'll be able to push this, given some time. :twisted:
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Unread postAuthor: c11man » Wed Sep 01, 2010 11:38 am

nice clean build, odd chamber design :shock:

i like the piston design but the oring might have issues coming off at high pressures.

how did it take you 90minutes to make just the piston? also i suggest boring out the back of the piston to reduce weight by alot improving preformace.
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Unread postAuthor: saefroch » Wed Sep 01, 2010 11:53 am

"odd chamber design" is intended to increase flow into the valve and look pretty.

Like I said, somehow I don't think that o-ring will come off at high pressures. It's not exactly your normal o-ring. OD: .5" ID: .25" and much harder than a normal o-ring.

90 minutes on a drill press trying to cut a groove 1/4" deep and 1/4" wide with maximum precision, then putting that cone shape on the front to help me force the o-ring on. To actually get it on I set it on the front of the piston, set it in a clamp and threw all my weight onto the clamp. When that didn't get it on all the way I jammed a screwdriver between the clamp and the o-ring and it popped on.
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Unread postAuthor: saefroch » Mon Sep 06, 2010 8:13 am

Bump for some damage pics and additions to the build log.
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Unread postAuthor: Crna Legija » Mon Sep 06, 2010 8:29 am

use a angle grinder to do the cutting while its in the drill press and it would have taken 1min, i used it in my 3way the first grove i did with a hack saw blade and it took 10min i was like ''fuk dat ima use the grinder' and it was way better, i finished it with a file.

you should drill out the back fill it with foam.
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Unread postAuthor: saefroch » Mon Sep 06, 2010 8:54 am

-_- I'm definitely using my angle grinder next time I make something on a drill press like that, took freakin' forever.

Saefroch wrote:Did some experimenting with GGDT... and it predicts no muzzle velocity increase with a UHMWPE piston having 1/8th the mass of the solid steel one I'm currently using. :roll:


I'll try reducing the piston weight at some point, but because of that prediction... it's not exactly at the top of my list.
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Unread postAuthor: Crna Legija » Mon Sep 06, 2010 9:08 am

Saefroch wrote: with a UHMWHDPE piston


lol where are you geting Ultra-high-molecular-weight polyethylene High-density polyethylene :lol:
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Unread postAuthor: saefroch » Mon Sep 06, 2010 12:21 pm

:oops: I honestly thought it was UHMWHDPE :oops:
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Unread postAuthor: jackssmirkingrevenge » Mon Sep 06, 2010 1:18 pm

Well put together, the piston is particularly sexy, though performance will definitely benefit from a lighter design :)
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