Hey crna just wanted to say thanks for this thread, I never knew these knives even existed and making them pneumatic is even cooler, yours inspired me to give it a go and Im pretty pleased with the results, for now it's only spring powered but I made an addition to the knife that adds an o-ring and I will be soldering a shrader into the handle.
It's all brass, copper, and steel the blade is made from an old chisel, range with the spring is about 25 ft which I think is fairly good, hopefully can be improved with some higher pressure from the pneumatic.
Posted: Mon May 09, 2011 11:56 pm
by jackssmirkingrevenge
Nice, that looks like a pretty heft spring but I'll wager power as a pneumatic will be miles ahead, and will not sound as "twangy"
Posted: Thu May 12, 2011 7:45 am
by Crna Legija
Hey very nice work there jor2daje :thumbright:, looks great! When your get around to making it pneumatic keep the spring in to see if it helps, i was going to do that but cant find a stiff spring the fits. Thats why i when down the pneumatic route.
i also have an update, more damage pics/vid. its only at 100psi again, because i cant find something good to shot at.
edit [youtube][/youtube]
Posted: Thu May 12, 2011 6:30 pm
by shardbearer
crna legija, that is a really nice looking knife. The main problem with the QD is the really short "barrel" length, like an inch, and that is a beautiful solution. I am trying to think up an easier way to make one, but that seems pretty simple.
And jor2daje, nice job there. I like it. Should be pretty powerful with both spring and pneumatic.
Posted: Thu May 12, 2011 10:21 pm
by Crna Legija
the blade has about 10cm of travel thats like 4''.
Posted: Thu May 12, 2011 11:32 pm
by jackssmirkingrevenge
Looking great!
Don't youhave a wooden plank you can test it against with the pressure ramped up?
Also, does it fly straight over distance or is there a tendency to tumble? Where is the CG?
Posted: Fri May 13, 2011 1:34 am
by Crna Legija
it fly's straight for abut 5m then starts to go side ways, ill try get some shots at wood board.
Posted: Fri May 13, 2011 2:16 am
by shardbearer
About an actual ballistic knife:
The spring in these knives is powerful enough to propel the blade to about 6 meters (about 18 feet) or more at 63 km/h (39 mph). They were not without drawbacks however: Because the projectile blade had no aerodynamic or gyroscopic stabilization, it was only accurate out to approximately 3 meters. Any further and the blade would often tumble and land sideways or tail-first.
The only ways to stabilize objects are through spin, fins, or having the weight in the front, none of which are viable for knives.
Posted: Fri May 13, 2011 2:50 am
by jackssmirkingrevenge
shardbearer wrote:The only ways to stabilize objects are through spin, fins, or having the weight in the front, none of which are viable for knives.
Not necessarily. The "handle" can be made out of aluminium, which would put the CG forward with a heavy steel blade. You can even have a telescopic tube than extends on firing.
It would also make sense to have a high aspect ratio dagger-like blade fitted to a relatively wide "handle" in order to keep the CP to the rear, as well as improving penetration.
Posted: Fri May 13, 2011 4:21 am
by shardbearer
To improve range you could have the barrel cover the blade, but that would defeat the ability to use it as a normal knife while in the barrel. O rings on the handle would also help range.
I wouldn't be surprised if they had a knife, no shovel projectile for that thing as the piston is separate, it really is a question of "whatever fits in the barrel".
Posted: Fri May 13, 2011 5:36 pm
by saefroch
Was that link intentional, JSR? The site it led me to redirected my browser to an X-rated website and tried to load a virus onto my computer...
Posted: Sat May 14, 2011 1:03 am
by jackssmirkingrevenge
saefroch wrote:Was that link intentional, JSR? The site it led me to redirected my browser to an X-rated website and tried to load a virus onto my computer...
Certainly not my intention. It's a perfectly innocent youtube link!
Thats why i when down the pneumatic route.
as the piston is separate, it really is a question of "whatever fits in the barrel".