Thanks for the feedback
psycix wrote:I'd like to share a few thoughts for improvement:
For more power, you could add some volume BEHIND the projectile, so that the pressure drops slower while the projectile travels.
One way to do this in a compact way is to create a coaxial tube around the launch tube, and drill a few holes in the side at the rear of the launch tube.
What if you would make the QEV dump an even higher pressure into the volume instead of releasing it? The pressure raises, the BD breaks (more cleanly due to more pressure), and the volume of air vents out near instantly, allowing the projectile to go.
What do you think?
The design is meant to be úber compact, which essentially means that currently all space is being used twice in there. By having space just for chamber air it strays from the original concept.
Of course by all means it can be done but I feel the best way to increase performance is raising the pressure.
On the alternative triggering method: I'm not convinced that would help too much, if you can use higher pressure in the QEV trigger, why not fill the chamber with it instead?
Also, if it doesn't work it now means the only way its going to fire is manually bursting the burst disk. Whereas physically ramming the burst disk can never fail on you, at worst the burst disk can be too tough and restrain the projectile while the air escapes.
I have got a new theory trundling about which should help the burst disk blow out instead of being punched out, less resistance for the projectile if the disk is greatly weakened before its shoulders try to muscle through.
A quick thought;
How much would the performance change if a tube was flared and silver soldered into the burst disk nut to extend the barrel twice as far as it is now.
It would give the launcher an appearance of a chamber and barrel with a mid valve. The barrel would be deceiving as it would look short but would pack the power of a longer barrel.
Again, this strays from the compact nature of it, as it is the projectile on launch almost doubles the length of the launcher before it finally lets go which is quite surprising to see...
The barrel would of course increase power but increasing barrel length will always increase power, in this case creating a dedicated barrel adds weight, length and added problems when fixing the burst disk due to a length of pipe now being on the clamp.
If on the other hand you increase the length of the main body, you increase the compressed air charge, the length of the "barrel" at the cost of a heavier projectile (the projectile has to extend the length of the tube).
Swings and roundabouts. I feel it's a reasonable tradeoff to have no barrel at all but have an extremely short launcher with an unbelievably large punch.
If you're wondering about efficiency by the way, consider how it fits together, the chamber volume is much less than the "barrel"volume which is literally the entire space of the projectile plus the empty space it leaves behind.
The projectile is ~57cm with an ID of 2cm, an OD of 2.5cm. Due to the way the nose was fitted actual internal is less than 57cm, perhaps 55cm.
I'm excluding the space between projectile and launch tube walls as I should really allow for blow-by as by nature it is not airtight.
So 55cm x 2cm diameter = 172.8cc
The barrel would be more or less 60cm and the ID of the launch tube is 2.6cm.
So 60cm x 2.6cm diameter = 318.6cc
PLUS the volume of the chamber
(until the projectile lets go that volume is still part of the system even though by conventional standards it looks insane as the volume being taken into account is now outside the boundaries of the pre-fired launcher)
So a total barrel volume of 491.4cc
Compare again to the 172.8cc of gas to start with.
Aroundabout a ratio of 10:28 between chamber volume and barrel volume.
Increased pressure and looking into ways of improving the projectile I feel are the ways forward. With over 1kpsi and still using the same 60cm long launcher tossing the 150g projectile massive range can be achieved.
All from a launcher which is lighter, shorter and simpler than a conventional one. Wahey