Brutal HPA BBMG idea

[jackssmirkingrevenge]

Much better now In your own time of course

[inonickname]

any takers?

Yep, how thick do you need the lexan disks, and any other parts as well?

[jackssmirkingrevenge]

Yep, how thick do you need the lexan disks, and any other parts as well?

Too late, looks like they've already been made!

As a side note, hadn't you flirted with this idea as well?

[inonickname]

Well, where's this gatling gun then?

Yeah, I originally thought of a rotary valve to feed each barrel and either a central magazine or a smaller centrifugal one for each barrel. Then that progressed to having a single long magazine down the bottom which fed spherical ammo into each passing barrel, and a constant flow of gas up the top. That was canned after worries of the ammo jamming inbetween the rotating mechanism (aka- the mag not feeding quickly enough) and wouldn't have been very efficient. If I can find suitable barrel stock (2mm for lead shot would suit me) then I guess I'll do it (with a vortex block from an onboard 30 bar supply which could act as a foregrip or from an airline). The only bore I have a large supply of spherical ammo for (and have barrels for) is..16mm.

[Brian the brain]

The only bore I have a large supply of spherical ammo for (and have barrels for) is..16mm.

Yes...that would be a problem.

[jackssmirkingrevenge]

It's up to the postman now (who still hasn't delivered my bloody servos, I should have checked the feedbackbefore ordering )

Assuming a BB feeds every 0.02 seconds from a typical vortex block, the barrels spinning at a relatively low RPM (say 1000) should not cause feed problems while still allowing a suitable high rate of fire.

As to barrel-chamber sealing, I was thinking about something like the attached diagram, having a sliding "piston" through which the ammo would travel, held in place against the rotor by pressure differential. This would of course cause friction but if anything it will help keeping the revs down

Yes...that would be a problem

Problem... or opportunity This is the beauty of working on a smaller scale though, projects that would otherwise seem out of reach are suddenly a lot more feasible, and using HPA small doesn't necessary equal weak.

[ramses]

some leakage would be desirable to keep a BB right against the plate to feed.

[USGF]

JSR,

The rubber might be a good thing. I have tried this in the past. The timing gets bad and the balls get caught in a shearing situation. Balls in shear not good.

USGF

[jackssmirkingrevenge]

Balls in shear not good.

He of the massive drill press has spoken

Fair comment, but small balls + 850 psi = fast balls, plus the RPM will be fairly low.

[jackssmirkingrevenge]

I've revived this concept using an idea I had proposed to Brian back on spudtech while discussing an efficient design for a marble machinegun, it's basically a variation of the "valveless" idea where the ball valve replaces the detent:



I'm using a 1/8" (5mm porting) ball valve this time around to avoid the jams that plagued the first prototype. The seal at the breech is necessary in this case as the ball valve is no longer sealing properly having been damaged with jammed 1mm BBs in a sentry gun prototype. The advantages of this setup however is that you need a lot less ball valve movement to fire as it is effectively only acting as a detent, and of course the tight breech should reduce rate of fire.

The prototype is curing, testing after at least 24 hours:

[bradisfun]

looking good cant wait 2 see more