Posts: 158
Joined: 1/20/2006 From: Yorktown Heights, NY, USA Status: offline
My valves arrived today and it was right down to the lab for a test session... It did not go as I had hoped. Pscartozzi was right on the money about the rapid firing of several bb's at once. I suspect it is a venturi effect. Essentially, as the first bb is fired the next few bb's are pulled into the "breech" by the air (CO2), flowing past the loading hole. A single bb loading system is a must in this case. Unlike pscartozzi, I am not using a modified airsoft gun mechanism. My design is all new scratch-built, very similar to the T-34 system pscartozzi made.
I might have a solution to this problem, but it will take time to develop. Besides the single bb theory, a fast acting triggering system must be developed as well. Updates to follow...
Posts: 977
Joined: 1/12/2007 From: Clifton Park, NY, USA Status: offline
As I mentioned, it's a black science in the beginning. It will take a few configurations to get some traction. I remember my first few tries being dissapointing. I've made some progress on a simple cycle breach made from styrene and brass tube. You should be able to duplicate easily. Back to the lab with you, we're almost there.
Posts: 158
Joined: 1/20/2006 From: Yorktown Heights, NY, USA Status: offline
The mad Doctor has been at it again... As was previously noted, there was a problem with multiple bb's being fired at one time in my gun design as well as pscartozzi's T-34 setup. I have come up with a gear driven loading mechanism that so far works well on the bench test.
I used two of the small nylon drive sprocket output gears that came with the tank as original equipment, shaved off the long flanges and drilled one of them out to fit my barrel, and CA glued it in place. The other gear was CA glued to a servo wheel. As you can see in my fuzzy picture, I made a wooden block to hold the mantlet and barrel. I was thinking to make a new one out of plastic, but maybe the wooden one will work for a while until I get all the bugs worked out.
In the wood block which I will call the "breech" from now on, I drilled a hole for the barrel and a hole for the bb's to load, ( the vertical hole in the top). The barrel has a hole drilled in it to allow a bb to drop in, with a small piece of poly tubing shoved in the back to prevent the bb from rolling backward, thereby allowing another bb to load. In the front of the loading hole, I drilled a tiny hole and inserted a tiny piece of rubberband in it to prevent the loaded bb from rolling forward, allowing a second bb to load, but when fired the rubberband will bend/stretch,squish and allow the bb to move down the barrel and out. I don't know how long the rubberband will last, but it was all I could come up with so far.
Now is where the gears and servo come in to play... On my Spektrum 6 channel radio, I have a landing gear switch and a flap switch, (ch 5 & 6). The gear switch, when pressed to the "down" position will turn the servo with the gear glued to it, thus turning the barrel with the gear glued on it 180*. In this "down" position, the bb loading hole will be facing down, sealed against the wood body of the breech, in effect preventing any air blowing out the hole= more power per shot. At this point, the flap switch will be activated to fire the bb. I still have to devise a fast acting triggering device, but I may have an idea in the works. I'll need to do some more research in that. After the bb is fired, I hit the gear switch again, servo turns back to the original "up" position, loading hole in the barrel is aligned with the loading hole in the breech, bb drops in. Hit the gear switch again, and the barrel turns once more to the "down" or firing position.
I still need to secure the servo to the breech, and I'll be using aluminum brackets for that. I have spent a lot of time just sitting on my floor looking at the millions of parts I've aquired for this mod, thinking and re-thinking how to do it. It's fun, but also frustrating. Next update in a few days... my brain needs a rest.
Posts: 1
Joined: 3/12/2007 From: masterton, NEW ZEALAND Status: offline
hi,barry from new zealand,a couple of months ago purchased a hl tiger 1.all works well apart from the plastic breach which i have made from brass.i have been following your ideas on the co2 powered gun with interest.20 odd years ago with spare time in the workshop i built a 177 bb gun using an air duster and compessed air.the hard part was stopping all the bbs firing out like a machine gun.finally came up with the shuttle idea.it has fired thousands of bbs with 100% success.the air passing thru the shuttle pushes it forard closing off the loading tube,returning for the next shot.the spring needs only to be very light.an indent ball just forward of the breach stops the bbs falling out,also uses a very light spring.i use 177 steel bbs.no idea of the velocity but it hits real hard.would pass straight thru the plastic tank.not a toy.the barrel is commonly available 1/4" brass tube with an id of approx .180" not sure of the gauge.have not tried lead bbs but i think they would work as well and not ricoche as badly.let me know what you think.i also have an idea for a trigering mechanisim using a servo and hammer(like a gas co2 pistol).regards barry
Posts: 977
Joined: 1/12/2007 From: Clifton Park, NY, USA Status: offline
Barry, Good to hear from you. Glad that our mad scientist work is appreciated. As you can see, we are working on a good loader/breach mechanism. I think a decent milling machine and lathe would solve most of these problems but oh well.
I just want to increase the FPS to allow me to break 6mm paint balls from 50 ft.
I'll probably have a go at this myself. I am going to build a stug III and I see this as being the perfect platform for a CO2 gun. No rotating turrent, just some elevation mechanics.
Posts: 977
Joined: 1/12/2007 From: Clifton Park, NY, USA Status: offline
Anyone making any progress out there. My Tiger gun is complete now. Still have to finish the T34. Anyone else have anything to post? I'm looking for inspiration.
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All Forums >> RC Cars, Buggies, Trucks, Tanks and more >> RC Tanks >> RE: My ultimate HL airsoft upgrade 
RE: My ultimate HL airsoft upgrade - 
As was previously noted, there was a problem with multiple bb's being fired at one time in my gun design as well as pscartozzi's T-34 setup. I have come up with a gear driven loading mechanism that so far works well on the bench test. 
