There hasn`t been much activity on this board lately either. Whats up? Everybody busy building stuff? Oh well. I`ve been working on 2 guns actually. I had talked about bulding a combustion powered bullpup rifle. I`ve split that one project into two. The rifle I jsut finished is a combsution powered rifle.
Pics here:
http://filebox.vt.edu/users/eneblett/Photo...bust1%20001.jpg http://filebox.vt.edu/users/eneblett/Photo...bust1%20002.jpg This gun is more of a technology demonstrator than a pratical rifle. Its about 5 feet long. And its pretty heavy. And its bulky. And its kinda frail. And.....you get the picture.
The technical stuff:
The propellant is 50/50 WD-40 and hairspray. That seems to be the most reliable for combustion. The large tank on the bottom is the fuel tank. Fuel is sprayed in through the ball valve and then the valve is shut. The tank is then pressurized with the pump on top. This pressurizing acts to do 2 benficial things: 1)Allows for 4-5 shots before requiring a repump or refuel and 2) greatly increases the O2 in the fuel-air mixture. Once pressurized the trigger on the grip is pressed and a small amount of propellant is released into the combustion chamber (the tank right above the fuel tank). A shell is then loaded into the breach and the rifle is ready to fire. Simply click the aim-n-flmae and you launch a dart about 200 feet. To prep the next shot the shell is removed, the fuel trigger is depressed, and a new shell is loaded. Thats it. The ROF is decently high for a combustion weapon. But the gun is still combersome and a pain. There is still an issue of reliability with the fuel igniting on command. If it fails to ignite usually if you spray a little more into the chamber it works. The breach is a very simple design. To load a shell you pull the barrel forward and insert a shell. Rubber bands hold the shell sandwiched between 2 O-rings. Pretty much the same sealing as in the bolt rifle.
Testing the rifle:
The rifle will consistently shoot a dart 150 feet. With a good tight dart and the correct fuel/air mixture it will shoot about 200 feet. Good figures, but the CO2 rifle will shoot about 150 feet and it is MUCH easier to use and aim.
It was fun building this gun and it works well. But I don`t think I would ever want to use it in any kind of battle
Semi-automatic Bullpup Rifle:
I am still making the bullpup rifle. It has been commited to CO2. I am very pleased with the performance of CO2 and now that I can get upwards of 20 shots per cylinder I beleive it is worth it. This rifle will be true semi-auto. Using a sprung bolt and the addition of a simple piston valve it should work quite well and efficiently. I haven`t thrown together a drawing of the semi-auto action yet but I`ll try soon. The gun will be about 30 inches long and use the same shells as my other rifles. The magazine will be a sprung bottom feed magazine of about 6-7 rounds. As in a bullpup setup the mag will sit directly behind the handle in the stock. The shells will eject out the right side of the stock via a dynamic shell ejector. I`ll post more on this gun when I make some siginificant progress on its construction. Right now I am jsut cutting pieces.
Combustion Rifle --- And Recent Developments, 200ft nerf rifle
Mar 23 2003, 09:41 PM
SWEET MOTHER OF GOD!!!! That thing is more like some pimped up sci-fi gun than a bull pup. Bullpups are supposed to be small. Good effort though. Also remind me never to play if your using that in a game...I'd rather not suffer 3rd degree burns from flaming foam. 
