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Old Jan 11, 2012, 08:48 AM
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kotori -
The BP burns and ejects leaving only a heavy "tarry" residue in the barrel. With teh single shot guns, they needed to be cleaned about every 5 loads. Can you tell us more about your guns and "more than 5 rounds"?

Warpd - i shot them off indoors (in a small garage) and the sound wasn't overwhelming at all. I shoot a 9mm Sig, much much louder. I would say that the BP loads Ray and I shoot are sometimes as loud or louder than the 22.
The smoke is there, but in no way the big cloud necessary for effect in a breeze on open water.

I have a new design completed and will test today, using straight BP loaded into a chamber and ignited by a single-use, thin copper wire that will totally burn-off instantly when powered, giving a faster and more sure ignition than the nichhrome reusable igniters now used (which can't be overpowered or they will be damaged)

Also, teh design is front ignition. Will see how that works for smoke and sound in testing later today.

My Trial version of Corel Draw expired - need to scan and post hand drawings....
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Old Jan 11, 2012, 09:21 AM
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You might look at .32 casings. You can buy just the casings, load them with what you like (including wad) and they're center-fire which means you can replace the cap or use the hole in another way. They'll last forever in these conditions - you'll lose more than you'll ever wear out. You can cut them shorter if need be too.
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Old Jan 11, 2012, 10:21 AM
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Dan,
Thanks for the relation to the 9mm. Having just when shooting for the first time a few weeks ago, that was very easy to relate. What is your test rig like? Did it fire through a barrel? I'm trying to envision the smoke you're describing. I'm guessing that it didn't "ball up" like the current guns, but expand and dissipate more evenly? It sounds like there's less grains in the .22 compare to your loads??

Jerry,
Can you provide a link to the casings? I've been searching but I must be looking for the wrong thing. Also, do you know the dimensions of these .32s much like what Dan provided earlier on the .22? I'm assuming a .32" diameter, but what about length and the rim size?
Gun dog has a .32 BP blank in this size, but WOW, it's over $25 for a case of 50! Big jump from the less than $10 on a .22... Now I know why I want to purchase a .22LR pistol... LOL
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Old Jan 11, 2012, 10:58 AM
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In looking, I found .25 center fire casings instead: http://www.firstclassbulletsandbrass...%26aid%3D57%26

These aren't primed, which means you have to get primers and press them in.

Specifications
Case type Semi-rimmed, straight
Bullet diameter .251 in (6.4 mm)
Neck diameter .276 in (7.0 mm)
Base diameter .278 in (7.1 mm)
Rim diameter .302 in (7.7 mm)
Rim thickness .027 in (0.69 mm)
Case length .615 in (15.6 mm)



Again; these are reusable - the .22 rim fire casings are not. They're only slightly larger. Just prime them, drop some powder in and wad with a bit of TP. You could put some pistol grease on them too, if you like.
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Old Jan 11, 2012, 11:31 AM
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Firing guns

Just tested a 15gr BP load in a test gun with front end ignition. A LOT OF SMOKE!!! It's breezy and cold here today, but teh cloud was still impressive - much more than I remeber from the current guns. There is a "whoosh" sound, no bang, but smoke is the really desired effect. Any sound from a reasonable load on a model will fade badly from out on the water anyway.

So, I'm focusing on BP loaded into powder chambers (cylinders) drilled into a delrin magazine block. 5 or more simple holes (5/16"D, 1-1/8" deep) is all that's needed - no casings etc. Fill is extremely fast with the calibrated BP loader I use. Then simply place the ignition wire in the slot provided and then cap-off and waterproof by pressing in a 1/4" long piece of foam backer rod as a wad.

Ignition was instantaneous. I really see a big potential improvement over the current guns in firing reliability, quantity of smoke and now the multi-shot capability.

I'll post hand sketches and a couple pics soon. Drawings when my new Corel software arrives.
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Old Jan 11, 2012, 12:13 PM
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Firing guns

Prelim sketches, some pics of the proposed multi-shot, hand-load, BP gun system.
Hope it conveys the idea....
Really limping along with no graphic or decent photo editing software...

The drawing shows copper wire as an igniter. Very thin nichrome worked muchbetter in the test. Note that the load moves into alignment with the stub barrel (by a simple servo-ratchet mechanism) and a rotary switch may still be used to control rate of fire. BUT it will be possible to align the barrel tube holes, ignition wire location and gun frame contacts so that the sliding movement of the magazine block will both align the gun barrel with the stub barrel AND align the contacts to fire the gun.
Note taht all the individual gun frames will be mounted on a single base with the slide advancing mechanism. To clean/reload, the whole set of magazine blocks (connected by threaded rods) will be removed. With the auto-BP-loader, loading will be fast and EZ.

The single tube block is oversized and for testing only. Actual magazine block will be 1/2" thick delrin, with at least 5 drilled barrels (maybe more). I don't even think a brass tube liner will be needed.

Anyway...on to getting materials for the build....when I get more time....
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Old Jan 11, 2012, 12:36 PM
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Dan,
Interesting new design... Do you see the ignitor wire surviving the blast, or will that need to be changed/replaced with each new load?
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Old Jan 11, 2012, 02:32 PM
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warpd -
Ignitor wire is now disposable. That is desirable:

In current guns, the nichrome wire must be given enough voltage to heat quickly and fire the charge, but not so much as to melt the wire. It's a careful balance requiring constant battery voltage (so a high capacity 10AH D cell 3V pack is used to prevent V sag during firing). Each ignitor - for all 18 guns - has to be exactly the same length to perform the same.

With a disposable ignitor wire, it can be undersized (small diameter) so it will heat very fast and burn out. Now the batt voltage is not so critical, the firing is very fast, etc. The batt V can be way in excess of what it takes to simply heat the wire - so the critical voltage balancing act is no longer necessary.
The system batt V sag and capacity will be a big factor with a multi shot broadside because the batt has to maintain adequate voltage for, say 5 x18guns = 90 shots! With a fixed ignitor wire, there is no way the V curve of teh batt would be flat enough to get repeatable ignitet performance over 90 shots. It's edgy now with only 18 guns when a second set of charges is fired.

If it all works, this system has potential to be the best of the gun versions to date. This will be generation 4.

The loading of the new system is easy: the attached set of 9 magazine blocks, 5 holes each, is set on end. The spring piston auto loader is used to precisely add the BP to each of the 45 barrels (insert loading tube into barrel, squueze piston, release - done). Then a short igniter wire is slid into teh slots, ends sticking out to allow contact with the electrodes in the gun frame. Then a 1/4" piece of foam backer rod (closed cell waterproof) is pressed in as a wad to compress the powder and seal the charge in place. No flash paper, guncotton, brass shells, etc necessary - only about 15gr of FFFG BP, 1" of very fine nichrome and 1/4" long piece of foam backer rod.
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Last edited by DanL; Jan 11, 2012 at 02:40 PM.
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Old Jan 11, 2012, 03:02 PM
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Nice! The only thing I can thing of, which I'm sure is already on your radar, is the alignment of the tube to the short barrel such that the wad is expelled and doesn't jam the system. I'm guessing the barrel would be a slightly larger diameter to accomodate?

To hold the nichrome and also act as a contact, what about something much like the metal component on the top of a roll of floss?
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Old Jan 13, 2012, 12:23 PM
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Firing guns

Warpd - stub barrel will be slightly larger ID than individual gun barrels. Stroke length/alignment will come from spacing of cogs activated by servo stroke. Alignment between guns will be by threaded rods connecting the individual magazine blocks.
The igniter wire will be slid into slots and pulled back and under 1/8" copper rivet heads.
Drawing shows latest ideas. Size shown holds about 15 grains (by weight) of FFFG BP. Delrin bBlock is 1.5x3.5x0.5", with five 11/32" x 1.25" holes.
I'll try to get vid of test gun shots when it warms up (only 6F here now).
Note front ignition - taht seems to give much better smoke & flash result. Seems to be a "burn" rather than explosion - good effect for the scale cannons...also likely minimal pressure.
(New drawing software - Corel Draw - very nice...)
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Old Jan 13, 2012, 12:49 PM
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Rivet heads, same idea, but MUCH more elegant than dental floss clips!

Looking pretty nice!

Which version of Draw did you get? I was looking at X4 ($37) and X5 ($67)
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Old Jan 17, 2012, 08:04 AM
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Firing Guns

Here's a shot at a design for the ratchet mechanism to move the magazine blocks exactly one barrel forward. The slots in the ratchet blocks will be angled saw kerfs, spaced the same as the barrels in the mag. block.
The arm on then servo will be articulated to be solid on the fwd stroke and to bend on the reverse stroke. An additional arm will lock into a groove to prevent backing of the magazine blocks.
Any ideas at a design to simplify this function?
1,2,3 - stroke of servo moves blocks forward exactly one tube
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Old Jan 17, 2012, 08:31 AM
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Looks great, Dan
This looks like a manual control on a 2-way switch on the radio. Click back, then click forward to advance to the next barrel. Is that what you're thinking?

I'll ask my LHS if there might already be such a mechanism out there.
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Old Jan 18, 2012, 09:00 AM
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Firing Guns

Mounting multi-fire guns with sliding magazine blocks looks like it will be tricky because of the curve of the deck. The drawing is a close approximation of how the system will look.
I'm thinking the gun frames will be mounted on a thin, solid, one-piece base o hold them in precise position. All the blocks will be attached to each other by single pieces of threaded rod, and move together through their respective gun frames.
There will have to be some flex between the blocks because of the curvature of the deck.
The ratchet mechanism will probably be between guns 4 and 5 because there is no room forward and steering gear takes the room on deck aft.
Still a lot o detail to work out for this to be functional.....
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Old Feb 16, 2012, 01:34 PM
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Firing Guns

Latest gun system design info posted at:
http://www.rcgroups.com/forums/showthread.php?t=1136541

Posted there because its getting to specific design for the Syren, and to keep the Syren post a bit more active. Seems it was about to disappear....
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