Miniature naval guns

[DanLew]

Just found this forum.  Need some help and opinions on very miniature black powder cannons please.
I built a 1/24th scale radio control sailing ship - 7ft long, 6ft masts, etc.  See attached pics.
The model has 18 firing cannons - no projectiles.  I made the barrels from 1/8" brass pipe nipples.  The ID (bore) of the nipples is 0.269" and they are 1.5" long. (Nipple dims:  ID 0.269", OD 0.405", wall 0.068") The brass barrel is inserted into the bored out resin barrel to make a scale model carronade (pics show the parts and a finished carronade)
Glow plugs are used to ignite the charge.  They are threaded into the breech.
Current load procedure:
1. Insert and compress a small wad of flash paper (from a 1/2" x 1/2" square) against the face of the glow plug (seems to prevent plug fouling from direct BP contact that occurs if no paper used)
2. Add 1/8 teaspoon Goex fffg BP
3. Add a wad - have used foam plugs and felt squares
I'm trying to get as much smoke and sound as possible.  The problem is that smoke and sound are really variable. It seems to depend on the wad - material, how tight, how much wall friction and how far I push the wad into the barrel.
Any suggestions on getting more uniform shots?  Fired the guns many times and no problems so far, but are the barrels adequate for this use?
Here is a video link to a broadside being fired (the sound is fake and dubbed in):
http://www.rcgroups.com/forums/showatt.php?attachmentid=2144527
Thanks much. 

[dan610324]

thats a very impressive build

welcome to the board

the rule of thumb when it comes to cannons is that the wall thickness of the surrounding wall in the chamber area should be the same as the bore caliber
but in this case Im really not sure if thats needed

there is a smoke powder used in pyrotecnic effects that you could try to mix with the powder
I dont know the name of it or where to find it
but Im sure that some googling will help you with that info

[Cat Whisperer]

DanLew --

WELCOME to the board.  You asked a mouthful!

Can't respond right now, have to get a few hours of work done on the roof before dark.

Have you considered the 'ladyfinger' firecrackers?

[FTB1-SS]

That is one nice ship and cool vid...... welcome, try looking a for some info from fireworks groups/boards there are some compounds that can be added to the charge to produce more smoke in the small amounts you are using.

[Cat Whisperer]

Glow plugs -- cool idea.  We'd discussed them a few years ago, but I'd never seen one actually USED for BP ignition.

Uniformity of ignition.  I'd start by making sure everything was uniform - measure each bore diameter, depth and charge.  Ensure that all wadding was uniform in size and insertion.

My thoughts are that with minimal charges any differences would be easy for the ear to detect; where with larger guns/charges the pain of the sound would make differences difficult to detect.

[Double D]

Get rid of the flash paper and let the glow plug ignite the powder. Make a wad cutter to cut .269 diameter wads from a plastic milk jug.

Sooner or later you are going to rupture one of those barss tubes and wreck things.  I suggest you consider upgradeing you carronades to steel.

[DanLew]

Thanks for the quick responses.

I'm going to order some sch. 80 316/316L SS pipe to make new barrels.  The bore is 0.215, wall 0.095, still not 1:1 ratio but better than the brass pipe now used.  At a barrel length of only 1.5" and no projectile, that should be OK given the high pressure rated stainless pipe, no?

The glow plugs gum up really fast in the recessed tube where the filament is located if powder is used alone.  Misfires increase as the filament fouls. The glow plug is "on" for a very brief time, because the firing circuit has to trigger 9 guns in a rolling broadside in 10 sec or less.  The flash paper is a pain, but it definitely keeps the glow plug cleaner a lot longer and it fires really fast.

I read about smoke powder.  Contains strong oxidant.  Both smoke powder and BP say don't mix with anything.  Anybody know if mixing is OK?

Uniformity - have a custom sized ladle to measure the powder.  The flash paper is accurately cut into the same sized squares.  The big change in sound smoke seems, from testing, to be mostly related to compression of the powder and wad and by how tight the wad is. Generally, a tighte wad gives louder sound, but less smoke and a looser wad gives more smoke, less sound.  I've used foam and felt wads - hard to get uniform.  Trying to understand what might give loud report AND big smoke.  The plastic bottle wad sounds worth a try.

[Double D]

Stick with your brass tubes, just make some steel outer barrel. Get rid od the Resin.

Do not use schedule 80 pipe, it is welded seam pipe and not safe enough for this use.  Read this post to see why. Weld Seam Liners

[DanLew]

This is supposed to be seamless sch 80 SS pipe, from McMaster Carr.
http://www.mcmaster.com/#46755k111/=3dmkae

[Double D]

Simple enough clean the gun between shots. If for no other reason than safety.

Construct some properly made guns.  It's only a matter of time before you have a burst.  Yopu have spent a great deal of time to create a beautiful model, why cut corners.

There is a process called duplexing, where a small amount of smokeless powder is loaded under black powder. It is supposed to make for a cleaner burn.  It also generates pressure spikes and with your type of cannon construction this can be very dangerous.

Generally its considered dangerous to mix or blend powders.

I know we have some folks here who work with pyrotechnics and can advise you.  Normally we don't allow pyrotechic discussions on the forum.  This is such an unusual application that I am going let this one continue.

You guys jump in here and help this fellow.

[Victor3]

"I read about smoke powder.  Contains strong oxidant.  Both smoke powder and BP say don't mix with anything.  Anybody know if mixing is OK?"

 Some smoke compounds use potassium chlorate/perchlorate as an oxidizer. You don't want to mix it with anything containing sulfer (like black powder). Such mixtures can ignite spontaneously.

 Might try a little flour on top of the wad.

[DanLew]

DD,
Thanks for the pyrotechnics clearance.  When I asked, I didn't know it was off limits.
I can't turn 18 scale profile barrels.  That's why I went to lining the bored out available cast resin barrels with pipe nipple barrels.  What approoaches could I use to make "properly made guns".
Would that info show upon a search here or could you suggest other links please.
I really appreciate all the advice and knowledge here.  I'm learning a lot of new info really fast.  Thanks.
Dan

V3,
I tried talcum powder, flour, cream of wheat, superfine sawdust, etc but really couldn't see any of it when the gun was fired.

Cat W, tried ladyfingers very early on, but couldn't ignite them.  Tried cutting them in half but they still didn't ignite. Never got one to ignite in a barrel.

[dan610324]

why not make one absolutely perfect carronade pattern in the correct scale
make it in 2 pcs as they are now

then find a small foundry working with lost wax castings,
have them use your model as a master pattern for the castings

complete them the same way with the stainless liner
and you have a cannon strong enough to use ffffg powder

now I probably will be killed because saying that   

but with that small amount of powder I think its safe to use ffffg in a stainless steel lined bronze cannon without any projectile

ffffg is much faster burning powder, more explosive
that will probably generate much more noice with the same amount of powder


DO NOT TEST THIS IN THE BARRELS YOU HAVE NOW
THEY WILL MOST PROBABLY EXPLODE AND CAUSE SEVERE DAMAGE TO YOUR BOAT


you could try to make one testbarrel from a piece of solid steel that  got the correct safety proportions just to test if it makes any more noice
1/4" bore mean minimum 3/4" outer diameter in the chamber area
use that test barrel for all experimental with loads and smoke making

[DanLew]

Ok - the barrels I have are inadequate.
I can't turn 18 steel barrels (or even matched brass barrels).  Basically, I'm hoping to stick to available materials I can work with.
Looking at seamless high P sch 80 pipe in different sizes, I can slip fit 1/8" pipe into 3/8" pipe and get the composite barrel shown in the sketch.
It meets the criteria of a strong material and a combined wall thickness just a bit thicker than the bore.  There is a 9 thousanths clearance between the two pieces.
The two pipe lengths would be assembled as shown in the second sketch, with the outside abrrel only being in the breech area.  I could insert this assembly into my existing carronades (resin barrel shown in dk gray in profile sketch).
Does the sketch look like an acceptable way to go?

[Victor3]

 In my opinion, what you show above should be fine. Only possible weak point I see might be in the threaded area if your glow plugs are aluminum. Even so, with blanks, it should be okay. With the small charge you'll be using, you're not likely to experience a catastrophic failure.

 If anything, I think you might have the resin underlug break.

[dan610324]

start making 1 of the liners and test with ffffg powder
I must agree with Victor here , the underlug will be a weak point in this design
maybe you should make it in steel and solder it to the liner, at least thats the way I would do it.

when it comes to the smoke I got an idea

when you load the barrel you first put in the flash paper and powder as usual,
then you add a smoke powder "cartridge"
made from kitchen plastic foil , 2-3 layers of plastic foil filled with a small amount of smoke powder
then the wad as usual
in that way the smoke powder have no contact with the black powder until you fire the gun

[Victor3]

"add a smoke powder "cartridge"
made from kitchen plastic foil , 2-3 layers of plastic foil filled with a small amount of smoke powder
then the wad as usual"

 Problem here is that with smoke compounds, they generally need high sustained temps to ignite. They also burn fairly slowly and need to stay in one lump to work well. Even if a "cartrige" of the stuff were to survive intact after firing (not likely), it would appear as a smoking 'tracer' flying through the air.

 Black powder by itself is probably the best white smoke-producing, fast burning stuff available.

 As an alternative to smoke, steel wool, fine mesh titanium or magnesium can be safely mixed with BP for a flash effect.

[dan610324]

yeah , but he wants more smoke .
must be a way to produce some extra smoke

[Double D]

There is only so much room in this tiny barrel.  Add chemicals reduce powder.

You mentioned not being to able to get firecrackers to ignite.  How much BP were you using.  Table spoons are for cooking and not shooting.  Get a proper measuring device and measure your charges.  The fuses on the firecracker should be cut in in half and 10 grains or less of FFFG or even FFFFg in this application could be used.

As far as fouling your glow plug, swab or flush your bore with water to rinse the fouling out between shots.

[thelionspaw]

Where are you located and where do you launch?  I'd sure like to see this masterpiece.

rc

[DanLew]

Thanks for the patient, continuing advice.

1. I'm going to failure test a current brass barrel.  Triple charge (3 x 1/8 teaspoon) with 2 x felt wad.  Also ordered some SS pipe to make the two layer composite barrel for testing.
Also talking to an expert machinist with a pattern tracer on his lathe about cost of making scale barrels with safe dimensions.
This quote is from the Cannon-Mania website.  It indicates thinner walls than the 1:1 bore to wall thickness mentioned the posts above.  Which is good?
"The diameter of the muzzle (open end of the barrel) should be roughly twice the bore diameter.  This means a .25 inch bore diameter should have a muzzle of .5 inch, and walls, 1/8 inch thick.  A .5 inch bore diameter should have a 1 inch muzzle, and a wall thickness at least .25 inches."

2. Measuring.  I use "1/8 teaspoon" to indicate the amt of fffg Goex used. I actually measure that amount with a powder ladle made for loading directly into the muzzle.  See picture.  Seems to be very reproducible.  A table I saw on Cannon-Mania indicates that 1/8 teaspoon is about 10-15 grains.

3. Did try flash powder.  Used the superfine metal powder part of the two part flash powder mix.  Mixed some in with BP. Did add flash but it pretty much eliminated any smoke.

4. Ahhh.... firecrackers WITH powder.  Did not try that.  Tried to ignite the crackers alone.

5. I'm located in Minneapolis MN

[dan610324]

that quote is dangerous thin,  VERY DANGEROUS 

rule of thumb is same wall thickness as caliber in chamber area

ok maybe thats slightly over built for blanks , but what do you prefer ??

 a safe barrel or a blown up boat with possible damages to people also ??

[BoomLover]

A very nice job on your ship model. I like the cannons, too, and a great little powder ladel. All around fine workmanship! BoomLover

[Double D]

You will not find Cannon Mania as a reputable or creditable resource.  Some of the information on theire website is contradictory and some safe, and some unsafe.  They are such an unreliable resource, I no longer list them on the Internet resource list for Cannons.  You do business with them at your own risk and peril.

Triple charge with a wad should produce a failure. If it does then your guns are real unsafe.

You might consider contacting our board sponsors for your cannons built out steel.

The powder ladle is for putting powder in the tube, not measuring.  Get a scale and measure, you'll get better results.

We may all seem very negative in our responses to your ideas, but in fact we are not!  This is a very interesting project and we are all very excited about helping you get it right!!!

Normally Minneapolis is just a gas stop on the way to see my Grandkids, but I would be willing to stop longer to see your ship in action!!!

[DanLew]

You guys don't seem negative at all.  I'm re-thinking everything now after getting your responses.  It's just a matter of how I get things done with the resources I have.  Also, I think I'm still learning a lot from all this, so I'm not finalizing my thinking just yet.
I am pretty stuck on the flash paper to keep the glow plug clear, though  : )

A key question - I think I can get carronade profile barrels turned - for sure in brass,maybe (but not likely) in stainless.  Would this profile (see pic) in brass be safe enough for the 10-15 grain (is that right for 1/8 teaspoon of fffg Goex) charge with felt wad?

DD, or anyone else... - any time (before the lakes freeze over) you want to come to Mpls, let me know.  We can go sailing and fire off some broadsides.

[Double D]

Brass might work, but to my eye, since you have so much invested already, I would go with the steel barrels. The original incarnations of the guns you are using were iron and painted black.

Before you get to hung up on the flash paper, do some experiments and determine if it is the sorurce of your ignition issues...I think it is.

Witha good tight fitting wad pushed down tight over the powder, you will get better powder ignition and it will burn cleaner.  You could also make a paper cartridge using the flash paper or the nitrated paper used in making paper cartridge.

Here is a link on how to make foil wrapped cartridges. Making Cannon Cartridges

Substitute the nitrated paper for the tinfoil.  You wouldn't need a wad.

Dixie Gun works and Buffalo Arms both sell nitrated papers.

[DanLew]

Double D -

Thanks for all your interest.  I really appreciate all the thought and time you're giving to this.

Brass might work, but to my eye, since you have so much invested already, I would go with the steel barrels
The only reason I would do brass vs SS is if the guy who has the lathe can't turn eighteen SS barrels.

Before you get to hung up on the flash paper, do some experiments and determine if it is the sorurce of your ignition issues.  
I did use just powder with no flash paper.  The first couple or three shots are OK, but then ignition starts to get iffy.  What happens is that the glow plug has a very small diameter recessed tube.  The filament is a coil deep in that tube. The tube fills with residue and swabbing doesn't get it out.  I had to pull the plugs and shoot a very fine stream of ammonia or vinegar into the recess and use a fine bristle brush to work out the gunk.

I usually fire about 5 to 10 broadsides at an outing.  With the flash paper wad, there is almost no gunk at all in the recess or around the filament.  It makes a big difference.  Also, I shoot plain flash paper charges for testing the circuit and guns.  Just a small wad, but it makes a "whoosh" and a flash and I can tell if the circuit, the guns and the firing rate are OK.  The flash paper ignites instantly and really never misses.

could also make a paper cartridge using the flash paper
I have made cartriges with flash paper tubes filled with powder.  The make loading a lot easier than the ladle method.  But what happens is that the cartrige is ejected before full burn, and I get a bang and a smoking "tracer".  Very cool effect, but can't have it do that because other ships are usually around at our shows (and they are flammabe!), and I think some people in the crowd would freak out if they thought the cannon was actually shooting a "projectile" of some sort.  The cartriges are wound around a 3/16 tube - pretty small to work with, but they are pretty neat.  I still had to use a wad.  Maybe I'm not compressing the powder enough?

The effect now is pretty good, but I would like to get as much more a cloud of smoke from the broadside than I do now.  One thing I tried with Pyrodex was mixing in some "smoke oil" for model train smoke makers. No real effect other than it seemed to reduce the bang per amount of powder used. 
I haven't tried smoke oil in BP yet.  Any thoughts on that?

[DanLew]

Battle pic.

This pic shows the frigate Surprise, a 9ft long three masted model built and sailed by a good friend from Kentucky, taking a broadside across the stern from my two masted brig Syren (about 7ft overall length).  Both are 1/24th scale.  We sailed together last fall in Minnesota on Grand Lake near St Cloud.  Planning another face-off on Sep 20-21 here in Mn again.

The pic shows why a blank charge with low mass, non-flammable wads are needed for our "playtime".

In even a light breeze, the smoke dissipates pretty quickly.  That's why I'm trying to maximize smoke.

[KABAR2]

Question are you firmly set on glow plugs?  you could have a traditional barrel made and use rocket ignighters with  the same results.
and they may actually be cheaper than the glow plugs even though you have to replace them every time.

[Double D]

Not stainless steel, 1018.

I agree with Kaber, about rocket igniters.

Also since swab won't work flood the bore with a syrings and then swab.


To maximize smoke turn off the wind...wait cxan't do that....