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The Cobra Venom

Unread postPosted: Tue Apr 14, 2009 6:14 pm
Author: Moonbogg
Introducing the "Cobra Venom" hybrid spud gun. If I am able to I would like make an insane pneumatic and perhaps a smaller piston hybrid for better portability and higher mixes.

(EDIT 10 years later, April 9, 2019. This cannon has served me with reliable performance for a solid decade. I just used it recently. This project was a 100% long-term success)

Specs:
2X hybrid/Advanced combustion
C:B Ratio: 1.22:1
Fuel-Propane/MAPP
1/4"NPT quick disconnect (Propane/MAPP)
Schrader valve (compressed air)
4.125" ID chamber X 18" long
1.87" ID barrel X 6ft long
2 spark gap spark strip
chamber fan-80mm 87CFM
stun gun ignition-150,000v
100% 6061-T6 aluminum construction-anodized, post weld anneal + T6 heat treat
2" Aluminum Camlock burst disc coupling & breech loading
1" ventilation valve-painted brass
1/2" X 12" Steel meter unit

Extras/misc:
Green laser (5mw) sight with pressure pad trigger on front grip
2" wide BLACKHAWK sling
UHMW bushings for smooth barrel movement
Black rubber grips
Modified project box enclosure with weather seal
Fan and Stungun toggle switches
Momentary pushbutton trigger
Bike pump with gage


Personal goal achieved:
Not a single hose clamp used and not a single wire visible on this cannon!!!! (besides laser cord)

http://www.youtube.com/watch?v=Nr-vXC8-qDM&fmt=18

PICS

Unread postPosted: Tue Apr 14, 2009 6:28 pm
Author: jrrdw
Outstanding build! I know I'm going to spend the next hour and half downloading the video. You shared the plans and everything, there should be a award given for times like this! PROPS Moonbogg, PROPS! :wink:

Unread postPosted: Tue Apr 14, 2009 6:36 pm
Author: MountainousDew
jrrdw wrote:Outstanding build! I know I'm going to spend the next hour and half downloading the video. You shared the plans and everything, there should be a award given for times like this! PROPS Moonbogg, PROPS! :wink:


I disagree... I think he deserves two awards! Great Job Moonbogg! I didn't understand most of the plans, but I understand the performance of the gun.

Unread postPosted: Tue Apr 14, 2009 6:37 pm
Author: LCTChamp
Wow it's absolutely gorgeous. It seems to be pretty accurate also. How far away were you on the shots? Are you only going to 2X because it is pressure rated to that or because it would kick to hard? I wish I had the money and/or access to a machine shop.

Unread postPosted: Tue Apr 14, 2009 6:46 pm
Author: MountainousDew
lctchamp wrote:Are you only going to 2X because it is pressure rated to that or because it would kick to hard?


Same question, and...
Is your chamber made of PVC? I wasn't sure because it says "aluminum construction" above.

Unread postPosted: Tue Apr 14, 2009 6:59 pm
Author: mark.f
Very nice!

I don't think I've ever seen a cannon this custom.

The fabrication itself is great, but that anodizing just sets it off. How much did you spend on this project???

Also, nice touch with the laser pointer, as well.

Oh, and, Duke Nukem... fun times... fun times...

Unread postPosted: Tue Apr 14, 2009 7:04 pm
Author: King_TaTer
I cried when I saw that you stole the name for an upcoming cannon of mine. :cry:

But I can't be upset you beat me to it fair and square and I know, you didn't steal it :) . Also I don't think my Advanced Combustion will be quite up to par with yours so it would seem like I'm trying to one up you. I did plan on incorporating Cobra somehow into the name though.

Back on topic:
Awesome work! :D It's one of the best Advanced Combustions I've seen in a while, and a HYBRID at that! Sounds kick ass when it fires. Exceptional accuracy is another thing I like about this cannon. You were able to consistently hit the targets you were aiming at. I'm starting to like the idea of laser sights, especially the green ones you can actually see. Not much left I can say other than great job. I hope to see more from you.

I do have one question. have you tried a pneumatic shot yet? If so it would be cool to see a video on it.

Unread postPosted: Tue Apr 14, 2009 7:31 pm
Author: Moonbogg
MountainousDew wrote:
lctchamp wrote:Are you only going to 2X because it is pressure rated to that or because it would kick to hard?


Same question, and...
Is your chamber made of PVC? I wasn't sure because it says "aluminum construction" above.


Whoa, thanks for the positive comments everyone! The cannon could handle more pressure. I just figured I would keep the factor of safety as high as possible.
I have never made a hybrid before so I was nervous with the extra power, so I started at 2X. I might go 3X, I duno. When I did the analysis on the cannon the aluminum didn't start to even bend until like 600psi or something, but that was a virtual test, not a real one. So I know I am totally safe with 2X, but it could very likely handle quite a bit more. Oh, but according to HGDT 3X would not provide much benefit over 2X unless I lengthened the barrel. So 2X really is the sweet spot for this baby in regard to power efficiency and safety.

There is no plastic on the gun, besides the project box. Its 100% heat treated aluminum for superior strength.

Unread postPosted: Tue Apr 14, 2009 8:42 pm
Author: sputnick
That perfectly square bit at the back is just crying for some form of shoulder support, that would be super bad ass. unlike all those little deep voice quotes in the video...

Sweet gun man, I am so tempted to put a laser on something now, I had almost completely forgotten about the idea!

Unread postPosted: Tue Apr 14, 2009 8:53 pm
Author: elitesniper
AW..I was hoping youd shoot the car.. :(
jk!
VERY,VERY,VERY! VERY!! Nice cannon! Bookmarked!
Is it anodized or painted?
And how many milliwatts is the laser?

Unread postPosted: Tue Apr 14, 2009 10:00 pm
Author: POLAND_SPUD
I suppose that the distance between him and the target was no more than 10 meters...

still the laser sight looks very very cool but it isn't really all that practical for long range shots... even with a quite powerful gun a marble (16 mm / 5 g) would need about 0.7 second to travel 80 meters (you can test it in ggdt and I tested it shooting today :-D ) so there is bound to be quite a lot of drop.. and lasers are no good for bullet drop


@King_TaTer
great gun.... it's quite compact for it's power and very nicely built...

duke nukem? man.... you're old :wink:


all of those CAD drawings make me think that the spuddign community is making a huge leap... now I have to mention what dewey does for the community by creating sketchup models of fittings and valves... I don't think he gets enough respect for what he does for all of us
:roll:

Unread postPosted: Tue Apr 14, 2009 10:35 pm
Author: grock
nice gun. as to your sabots, try getting a piece of newspaper, ball it up, stuff it down the barrel, then take another piece and fold it into a rectangle about an inch wide and wrap the golfball in that (like saturn's rings, not all over) to keep it centered in the barrel. should help some, but it looks like youve got pretty good accruacy anyway

Unread postPosted: Wed Apr 15, 2009 12:40 am
Author: VH_man
beautiful. Simply beautiful.

This is my favorite hybrid on this site. Officially.

Proboably the only hybrid i know of that looks just like a normal combustion though haha. its why I like it so much though.

Unread postPosted: Wed Apr 15, 2009 1:00 am
Author: Moonbogg
grock wrote:nice gun. as to your sabots, try getting a piece of newspaper, ball it up, stuff it down the barrel, then take another piece and fold it into a rectangle about an inch wide and wrap the golfball in that (like saturn's rings, not all over) to keep it centered in the barrel. should help some, but it looks like youve got pretty good accruacy anyway


Dammit!! Thats perfect! Nice idea. I can't wait to try it. It really sounds like it will work. Like you said, the ring keeps it centered and the wadd behind it simply blows it out. Thank you.


POLAND_SPUD wrote:I suppose that the distance between him and the target was no more than 10 meters...

still the laser sight looks very very cool but it isn't really all that practical for long range shots... even with a quite powerful gun a marble (16 mm / 5 g) would need about 0.7 second to travel 80 meters (you can test it in ggdt and I tested it shooting today :-D ) so there is bound to be quite a lot of drop.. and lasers are no good for bullet drop


As mentioned at the end of the video the golf balls spin so hard its funny. They have done in-flight curves at nearly 45°!! Straight up! So distance and accuracy with golf balls is limited. The shots were around 10 yards from target except for the last one. That last potato shot was about 20 yards maybe. Not bad for a spud.
Oh, the laser has elevation and windage adjustment, so you can easily dial it in for whatever range you are shooting at, just like a real gun would. With better sabots the golf balls ought to fly pretty straight and certainly much farther in an accurate fashion. Some of my shots that day were really straight with great power. It seems I got lucky with those crappy sabots here and there.
Thanks for the feedback.

elitesniper wrote:AW..I was hoping youd shoot the car.. :(
jk!
VERY,VERY,VERY! VERY!! Nice cannon! Bookmarked!
Is it anodized or painted?
And how many milliwatts is the laser?

Anodized. The laser is 5mw, the maximum US legal limit. I updated the specs to show this. Thanks.

Edited to post HQ video version:
http://www.youtube.com/watch?v=Nr-vXC8-qDM&fmt=18

Unread postPosted: Wed Apr 15, 2009 3:49 am
Author: Xerxys
You need to fire ten thousand bbs simultanainiously. Then we will see the true power of this beast.