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Cannon #5 - Metered Pilot Isolated Piston Hybrid

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Cannon #5 - Metered Pilot Isolated Piston Hybrid

Unread postAuthor: PCGUY » Wed Sep 02, 2009 11:55 pm

Cannon #5

(Manometrically Metered Pilot Isolated Piston Hybrid )

Final Judges Score Chart
-Idea 5.4/20
-Use of materials 3.2/5
-Creativeness 2.1/10
-Quality of build 2.5/5
-Function 7.3/10

This cannon is part of the SpudFiles Innovative Contest. For details see here...
http://www.spudfiles.com/forums/spudfil ... 19233.html

--Details and pictures from cannon builder--


Chamber: 2" SCH 40 galvanized, 12" long, plus a lot of fittings.

Barrels: .5" copper 10' long, in 5' segments. 2" EMT conduit 10' long, also in 5' segments

Valve: .75", .5" porting, O-ringed piston. O-Rings allow pilot to be filled to a different pressure than the chamber, allowing opening pressure to be adjusted Independently from mix #.The dead space is filled with caulk, so the air spring has an acceptable compression ratio.

Piston: Machined aluminum, 2 O-Rings. Re-enforced rubber sealing face


Mix: 2x-10x (limited by compressor)

Ignition: Camera flash/ Iggy coil. The trigger electrodes can be hooked up to any extension cord, allowing me to be 250 feet away when I fire the cannon. The most I ever use is 50 feet.

Spark plug: Drilled out bushing/ filed down automotive spark plug JB-Welded together.

Meter: modular quick connect, manometric.

fuel meter:

air meter:

nozzle: homemade venturi designed to aid in fuel mixing, as I was having problems with this earlier. IIRC, the holes are .02" diameter


nozzle before insertion into tee

Noise level: Surprisingly quiet when a paper towel wad is used with 10' barrel. Multiple echoes around my rural neighborhood when shooting blanks. Absolutely deafening in my basement at 2x with no barrel.

Future upgrades:

-bolt action system for 1/2" copper barrel

-2" piston valve, magnesium alloy for 40% less weight, if I can find some rod for less than $80 shipped. I may melt scrap, but melting several pounds of flammable metal that will evolve hydrogen and steam if it contacts water seems rather unsafe. I also lack a suitable inert gas cylinder.

-Barrel supports!!!

Innovative design:

-Ignition system that uses extension cords to extend range, without buying extra wire. (currently too ghetto to include pictures of)

-Pilot area sealed from chamber to allow opening pressure to be controlled separately from mix number

-Nozzles to aid in fuel mixing (see above)


AA vs milk jugs of water (hgdt says 1000fps)

AA vs. steel plate (1000fps)

hardened steel nail vs. steel plate (1500fps)
Nail after shot

golf ball ricochet off steel plate (283fps based on video)
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Last edited by PCGUY on Fri Apr 16, 2010 1:07 am, edited 4 times in total.
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Unread postAuthor: Hubb » Thu Sep 03, 2009 9:27 am

Idea - 5
The only innovative part that I think is worth mentioning is the independent "pilot" area to control the opening of the piston.

Use of Materials - 5
The builder did use the materials as intended. It's nothing new, but they are used right.

Creativeness - 1
Again, nothing new. This is nothing more than a hybrid launcher. It does have the piston valve rather than a burst disk, but that's been done several different times.

Quality of Build - 3
It just uses pipe fittings. We see those every day. It's nice, but not different.

Function - 10
I'll give it a good score here because it does seem to function as intended.
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Unread postAuthor: MrCrowley » Thu Sep 03, 2009 8:23 pm

Idea: 5
Everything seems to have been done before, even the 'air bumper' in the pilot to control when the piston opens has been done before. Nonetheless, you don't see piston hybrids very often, nor ones built this effectively.

Use of Materials: 5
Nice touch with the venturi fuel nozzle, good improvisation with the materials at hand.

Creativeness: 2
Been done before.

Quality of build: 3
Not much to screw up on when you use normal pipe fittings, but it is still built well implementing a few good ideas and a well made o-ringed piston.

Function: 9
It seems to work well, aside from the fact the builder had problems with metering to begin with.
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Unread postAuthor: starman » Thu Sep 03, 2009 9:35 pm

Score Chart
-Idea (20 pts max) 7 - Just a piston hybrid. While not many are around, not much to score on innovation.
-Use of materials (5 pts max) 3
-Creativeness (10 pts max) 4 - Fuel mixing venturi nice touch
-Quality of build (5 pts max) 3
-Function (10 pts max) 8 - Lack of barrel supports
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Unread postAuthor: clide » Fri Sep 04, 2009 1:27 pm

-Idea (20 pts max) 6
Neat, but not really new

-Use of materials (5 pts max) 3

-Creativeness (10 pts max) 1
Not really seeing anything

-Quality of build (5 pts max) 2
The piston is nice

-Function (10 pts max) 6
It seems to work based on the video, but with apparently no breech loading device I'm not sure the cannon is getting much functional use out of the piston. Also with no holder for all the components it is probably a bit of a pain to setup.
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Unread postAuthor: jackssmirkingrevenge » Fri Sep 04, 2009 11:13 pm

-Idea (20 pts max) - 5
-Use of materials (5 pts max) - 3
-Creativeness (10 pts max) - 2
-Quality of build (5 pts max) - 2
-Function (10 pts max) - 7
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Unread postAuthor: jrrdw » Sat Sep 05, 2009 8:36 am

Idea: 2 nothing new.

Use of materials: 4 he used them.

Creativeness: 1 nothing new.

Quality of build: 4 it is put together nicely.

Function: 10 it works like it's sapposed to.
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Unread postAuthor: CS » Sat Sep 05, 2009 4:26 pm

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Unread postAuthor: jagerbond » Wed Sep 09, 2009 1:22 am

-Idea 6
-Use of materials 2
-Creativeness 3
-Quality of build 1
-Function 7
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Unread postAuthor: sgort87 » Fri Sep 11, 2009 3:55 pm

Idea: 6
There really isn't anything new on here, as already said.

Use of Materials: 1
There are a lot of extra fittings on there that just clutter things up. Next time, try to find fittings that will give a more compact and simple design.

Creativeness: 2
There isn't much of anything clever in here besides the mix nozzle, and even then, I've seen it before.

Quality of Build: 3
For the materials chosen, it was put together pretty well.

Function: 4
Sure, it functions as intended, but it isn't a practical shooting device since it takes so long to set up and has no automation at all.

Don't let this discourage you from trying again. Here's your prototype, now go and build something fantastic with this concept using better materials and automation.
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Unread postAuthor: Brian the brain » Sat Sep 12, 2009 5:18 pm

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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: inonickname » Sat Sep 12, 2009 10:46 pm

-Idea: 4; Not new. Piston hybrids have been done, the only innovative part I see is the independent pilot filling.

-Use of materials: 3; These parts are available to everyone; so it's great in the thought that it could be attempted by many people but unfortunately seems a little 'run of the mill'.

-Creativeness: 3; Similar to the idea part. It's been done, and the parts seem rather 'stock'.

-Quality of build: 2; it's put together neatly, but there is unfortunately a lot of parts which are as they can be bought; some customization wouldn't go astray.

-Function: 8; it's a piston hybrid. No burst disks is excellent. The independent pilot filling no doubt offers improved performance over a normal piston hybrid.
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Unread postAuthor: THUNDERLORD » Sun Sep 13, 2009 6:43 pm

Well the "J" shaped nail was also innovative IMO.
IDK how a "piloted piston hybrid" gets piloted(?)
Seems very innovative pilot on it, Guess I've got something to study later.
I like the over-under design too!!! 8)
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