Design Details for R/C Square Rigger Operating Systems - Page 12 - RC Groups
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Dec 29, 2011, 05:37 PM
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FIRING GUNS - electrical ignition of 22 rimfire

Here's a concept drawing for an electrically fired 22 cal BP blank rimfire revolver mechanism.
Next is to figure a best way to get 1/4 rotation of the cylinders to align each new blank exactly with the stub barrel.
With the 9 guns on Syren, all will be on a solid base that slips into place on deck, with all guns aligned in the gunports.
To clean, the whole assembly can be pulled.
To reload, the cylinder pin is pulled and the cylinder pulled free.
The positive electrode is lightly spring loaded to just contact the cartridge rim.
With a very short cylinder - it should be only as long as the blank casing - and a very short barrel, and with a short BP charge, barrel pressures should not be too high. So maybe cylinder made up of sched 80 pipe would be adequate.
All this has to be fairly simple and low cost because for 18 guns, that's a lot of separate parts and assemblies.
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Dec 30, 2011, 09:43 AM
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Do any of you have the number of grains you're currently loading into the guns today? I still have the prototype Ray sent me and am going to bring it with me to the gunsmith tonight. I'd like to be able to tell him the size of the load when we talk. This will give us a good reference to the load in the .22's.

This assumes we get past question #1 - Am I legally able to purchase/possess .22 cal BP blanks in NYC. If the answer is no, he may not go beyond that in conversation.
Maybe I'll call first and possibly save myself the gas money.

To your design - do we need to rotate the cylinder at this point? If using electric ignition, could we not keep the cylinder static, provide common ground and an electrode to each blank. Then using a system simliar to what I designed previously, trigger them separately? For the barrel, we can modify a similar design from maxtronic's setup. This would aid in legal issues as the system couldn't be made to fire a real bullet, as well as limit fragments from exiting with velocity. This does create a potential back pressure scenario that we'd need to test and I'm not sure if there's any concern with chain firing as the blanks are factory sealed.
Dec 30, 2011, 12:01 PM
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Firing Guns

warpd - I can't remember the grains used and don't have access to my old notes. Maybe its posted somewhere.
But the amount of FFF BP, very loosely packed, is about 3/8" high in a 1/4" OD tube.

My impression on the NYC legality is that if its used for theatrical use, blanks are OK. If you call the online place that sells them, they will be able to tell you if they can ship to NYC.

On the separate ignition for each barrel topic....with just 9 guns on each side, using a common ground, the amount of wiring and complexity of the rotary switch becomes a pain in the butt. Having 36 separate positive leads to all the individual 9 barrels on both sides would be a birdsnest (for my skill level anyway).
Also, the rotary switch size and contact spacing limits the number of contacts that will fit in 360 degrees.
Now thinking that a pre-cocked firing pin for each barrel, triggered as the blannk comes into position, may be the way to go. Lot's of testing to be done...
Dec 31, 2011, 11:56 AM
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Sorry this was posted in the wrong thread while on my phone...

Good news (for you guys, not so much me). I spent about two very informative hours at the gunshop. He did chuckle at first, and then tell me what I pretty much know - i cannot legally purchase or possess ammo. And technically, once I put BP in one of the cannons, NYC would consider it a weapon (to the letter of the law). (I am not a legal theater company so the theatrical plan doesn't apply) Beyond that and me telling him our intentions; showing him Dan's old prototype cannon and all of our design drawings; he even asked about video so I pulled up some of Ray's youtube footage. He was very helpful. As soon as I get in front of my PC with my notes, I will post everything.
Dec 31, 2011, 12:15 PM
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Minutes from chat with Gunsmith.

-If we make our own cylinders and barrels Brass will work fine for .22 cal BP blanks as BP is a progressive burn. It wouldn't work with newer smokeless rounds - which we luckily won't use.
-He suggested using spent .22LR casings cut down to the size we needed (at the point he mentioned this, I told him about the .22 cal short BP blanks that Winchester sells. He wasn't aware of them, but said "well that would surely work)
-He showed me a series of Vest pocket pistols sold by North American Arms... THEY ARE SMALL. the cylinders hold 5 .22 rounds. He showed me how they could work well with some modification. However, at around $200 per gun, that's a bit pricey, HOWEVER, the size and layout does closely match Dan's design so this is a good sign.
-he also brought up an idea in line with Jerry, on using Percussion caps, some loose BP and nitrate paper (or even a piece of flash paper) in a muzzle load, place the cap first, then BP then paper to hold in place. We could use the same Kricotronic style method to trigger the percussion cap. He believes that would provide a good sound, smoke and flash while keeping pressure to a safe level. This is of course loadable into a cylinder directly (if using a cap & ball style cylinder) or into a spent .22 casing (if using a breech load cylinder design).

I would need to obtain a pistol license (and a .22cal handgun) to be able to purchase the blanks "legally." They are my ideal preference in this as they are ready to use. I would rather spend the $8 for 50 rounds than spend some hours filling cartridges, so I may have to look into this.
I may try mocking something up in wood.

I hear you on the mess of wires. Sounds like a single electrode and rotating cylinder is the way to go. This does jive with the Gunsmith's feel that directly aligning the round to the barrel (with a blocker bar of sorts in front) is the better way (from looking at it on paper). I had drawn out a design that had a conical tube inside. He said that could possibly lead to some unwanted back pressue and maybe cause a chain fire. Will try to post some drawings and other info this weekend... Happy new year's all.
Dec 31, 2011, 07:29 PM
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Firing Guns

warpd - great info from the gunsmith. thanks for taking the time to get it.

here are some thoughts on gun operation. Ray - chime in here because you have a great perspective on this too.
When actually sailing the model and trying to maneuver into a firing position relative to the enemy (AKA Ray and Surprise), the gun system needs to be pretty simple to operate and very reliable. Things like firing the guns individually, etc take a secondary priority to controlling the ship (and doing video and maneuvering the chase boat!). Basically, a continuous slow rolling broadside gives the most bang for the buck. Onlookers seem to like the sequence of shots and the clouds of smoke. Fire all the guns too fast and its over before people can react and respond. Fire too slow and the broadside seems disjointed. I think I fire 9 guns in about 10 sec, and Ray maybe at a similar rate. That seems like a good rate for public display.
So a new system would be nice if it had a single control that started a timed firing sequence of all the guns in a group.
I'm still thinking a low RPM gear motor with belt or mini-chain drive to turn the cylinders, with the cylinders positioned to fire in slow sequence as the single drive unit turns them all at once.
harder to explain than draw. more later....
Jan 01, 2012, 01:03 PM
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Sounds like you need a first mate!. Ha, don't we all. I am definately all in for simplicity in firing. Having flown scale warbirds, dealing with 9 channels while keeping my eye on the bird the entire time to avoid a tree...or the ground... I guess, im coming from a different angle on what's complex and busy. So feel free to remind me im going overboard once in a while. Lol.
I may have some more info worth posting from the chat, but I need to review the notes some more and find time to sit. Holiday weekends are too busy.
Jan 04, 2012, 08:47 PM
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Firing guns

Black Powder

Warpd asked how much black powder is used in the guns on my Syren and Ray's Surprise.

We use a custom built filler that dispenses a fixed volume of BP. I measured the total dispensed weighht of 31 charges = 27grams.

That's 0.87g/charge.

1 gram = 15.4 grains.

15.4 x 0.87 = 13.4grains per charge
Jan 04, 2012, 09:39 PM
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Firing guns

Here's a conceptual sketch of a 3-barrel/gun cannon to fire a 22 short BP blank with electrical ignition.

The weight of a 3 barrel gun may not come out too badly because each barrel element in the cylinder is only about 1/2" long. A single current gun on Syren is 66grams. The 3 barrel sections on this design will weigh about 18 grams, so a complete gun will likely be in the same weight range as a current single barrel gun.

The electrode (7) is held in place by a spring (6) to insure contact with the rim of the cartridge (5). The electrode is a tungsten welding electrode - cheap and will hold up to the electrical arcing at the rim contact point. The gun frame (3) will be 1/4" PVC sheet stock - plenty strong and easily cut and bonded.
The "stub" barrel (1) will show through the gunport. The cylinder (Sketch B) will be made up of three pieces of sch 80 brass pipe, each about 1/2" long.
Sch 80 has to be used because sch 40 has too big an ID (see Sketch A). The sched 80 will need to be reamed out very slightly to accept a 0.22 cartridge.
Stub barrel mounting screw (2) will hold the stub barrel in place and serve as a blocking pin in the barrel to prevent shooting any projectile.
The cylinder is held in place by the cylinder shaft pin (8). Pull the pin to drop the cylinder for reloading.
BIG DESIGN GAP: How to rotate the cylinder to precisely align with the stub barrel and the firing electrode. Thinking of using the cylinder shaft pin(8) as a hub for a belt drive going from gun to gun. The belt drive would rotate the pin (which would be keyed to rotate the cylinder) using a gear motor.

I used only three barrels per gun because 4 got a bit bigger and heavier, and for a total of 18 guns x 3 shots per gun - or 54 shots, or 6 broadsides per outing, I thought that would be enough. Also, 3 barrels allows more alignment latitude (120 cylinder rotational degrees per barrel) tha 4 barrels (90 cylinder rotational degrees per barrel).

Still an early concept design, but at least seems feasible at this point.

NOTE: I ordered a box of 22 cal, short, BP blank cartridges to check out smoke, sound, recoil, etc.
Jan 05, 2012, 08:10 AM
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Firing guns

Ok, multi barrel cylinders, rotation mechansims, etc....
That was Gatlin Gun....move ahead in history to...
Machine gun with gun belt! (Not to the AK yet....)

Trying to use a belt to rotate all the cylinders into a precise position led to using a gunbelt approach. Requires only one barrel per gun with a receiver, has room (on Syren) for SIX cartridges per gun, and the "belt" (actually a very stiff or even solid strip) can be easily and precisely ratcheted forward by a servo stroke.
Does seem to require 22 cal blanks vs 'home rolled" cartridges though.
That will require the success of electrical firing of the rimfire, or a re-cocking mechanism witha trigger/sear/hammer action for each gun.
New concept drawing attached of the single belt - shows 6 belts representing the forward shift of the single belt to position a new cartridge in each gun. Working on a gun design that allows the belt feed....
Jan 05, 2012, 09:33 AM
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Dan, interesting idea!
I had been thinking about a way to rotate the electrode and leave the blanks in place. The electrode would have a touch more tolerance on it's rotation and we'd be able to "lock" the rounds in alignment with three inner barrels that would angle into the singular muzzle opening. I have a rough sketch at home, that I will upload tonight.

I (still being newer to this) am still attempting for a some what scale design. Being 1/20 scale gives me a bit more size to work with, so I'm hoping that's the trick.

Taking into account, the cost of the blanks, the ability to work PT and STBD, and the additional design challenge, I think you are right with sticking to three rounds per gun in the "standard" design.
The gunbelt seems interesting, but I'm still trying to visualize the device which holds the rounds. Also, I realize we'd be sailing with 108(Syren), 120 (Rattlesnake) and... wait for it.... If Ray arms ALL gun ports, up to 216 rounds on Surprise! Seems like a lot of munitions on the ship. I know we don't "have to" fire all charges every time we sail, but I'm just wondering if there's any reason for worry with that many blanks on the ship. Just having my dooms-day hat on here.

Let us know how the blanks work out! Since I can't order them, I can't try them myself at this point. I really want to though.. LOL
Jan 05, 2012, 09:57 AM
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Firing guns

Here's a "gunbelt" approach that simplifies a lot....
Jan 05, 2012, 10:16 AM
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The simplest notion of this would be a stick feed - a flexible belt or links would require a spring/gas system to chamber and extract the cartridges. Your "stick" would not only hold the cartridges and advance them, but would serve as the breech block so the cartridge would not have to be pushed into and extracted from a chamber.

If the cartridges aren't too strong, the gun barrels could angle down in back, through the deck, and the whole mechanism could be hidden below leaving fairly scale looking guns on deck.

The "stick" could be changeable and slip onto a trolley set-up so reloading would be easy - just remove the spent stick and insert a loaded one.

The crude drawing attached isn't to scale, (are they ever?) but I hope illustrates the idea. Sorry, I'm on my laptop waiting for my replacement power supply to arrive for the desk-top PC.

Anyway - the stick is Delrin, Teflon, hardwood, whatever. The cartridges friction fit into it. The breech block at each gun backs up the cartridge against recoil and holds the firing electrodes. The barrel is copper tubing slightly curved to get everything below deck.

This assumes the blanks are low powered enough to not blow this all to bits - BP starter pistol blanks should be ok.
Jan 05, 2012, 10:40 AM
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Firing guns

Thanks for chiming in....
It would be graet to have scale guns and the mechanism under deck like you show.
No way I can get under my deck again, so I'm left with option of a set of non-scale firing guns for sailing battles and a separate set of scale guns for display.
The stick idea is great. The "belt" idea kind of morphed into short "sticks" like you show, but all connected by threaded rods (to fine tune spacing and cartridge location). The whole "belt" assembly holds the cartridges and slides through each gun body, aligning with the barrel of the gun. Each body has it's own eelctrical contacts to trigger the rimfire. The cartyridges stay in place after firing and the stick slides to position the next new cartridge.
A single servo, per side, does a full swing through a ratcheting mechanism that advances all the attached "sticks" in the "belt" the precise distance to the next cartridge in the stick. The belt "stick" shown is 3/8" thick PVC, drilled to hold six brass tube liners (1/4" brass tube, ID = 0.222"), which in turn holds the 0.22 blank.
The big challenge is whether the rimfire can be triggered by arcing current on the rim using a short piece of tungsten welding rod as the electrode.
Should have some blanks by early next week to start testing...lookout fingers....
Jan 05, 2012, 12:00 PM
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Jerry... Nice Carronade... I used the same one off the web! I have a variation on that. I just did a kindergarten version in Paint so as not to wait until 10pm tonight. So sorry for the poor graphics... again

Do you know how many grains are in the BP blanks?

Ok, so in the crayon drawing. I have set up for 4 rounds. The green circles show the cross section of the barrel at that entry point from the charge (4 red circles) to the exit at muzzle (4 tubes cut and linked into one. I'm thinking to mold this in resin or wood and sleeve the inner tubes with brass.
Each blank lines up with a tube and has it's own hot (common ground) running to under deck where the will be a servo controlled selector. This will be mechanical off one servo (this will look similar to Dan's gunbelt design). Doing this allows only one hot wire to each gun from the triggering system eliminating 40 or more extra wires. Personally, I thinking avoiding a rotating cylinder and risking misalignment is preferable. The diameter of the cannon at the point where the blanks are loaded is just less than an inch.. possibly 7/8's depending on wall thickness.

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