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HMS Victory by dafi - Heller - PLASTIC - To Victory and beyond ...


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- Dr. Tentacle is still there to all eternity - he can´t move any more 

 

Are you sure - a week is a long time,

 

Do not worry, I will have a close eye on him :-)

 

Thanks Kevin, Ian and Channell

Edited by dafi
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Beautiful work, Dr. Dafi! 

 

Looking through several references on naval ordnance, I could not come across any that showed a second preventer breech rope.  Not sure where Goodwin got it from, but what the heck!  A quick look in Goodwin at the section on ringbolts etc for guns references the Shipbuilders Repository of 1789.

 

There is a great contemporary French drawing available via Wikipedia (i know, not the best of authoritative sources) - see http://en.wikipedia.org/wiki/File:Antoine_Morel-Fatio_pl10.jpg%C2'>

 

I also looked through Captain H. Garbett, RN, Naval Gunnery from 1897.  He has some great illustrations of late 19th century and older naval ordnance, but the only one of the carriage was again sans a second breeching rope.

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Hi Daniel

 

Two possible explanations:

 

Powder burning produces gases and heat. It's that heat that makes the gases expand and increases pressure within

the barrel eventually expeling the ball.

the metal of the barrel absorbs some of that heat. As it gets warmer and warmer less and less heat it absorbs leaving more

to expand the gases leading to increased pressure higher muzzle velocity and higher recoil.

 

That's one

 

Another would be that as the gun heats the outside diameter increases and the inner diameter decreases as the muzzle wall

expands and you have a tighter fit with less pressure loss.

 

 

But sincerely....... I really don't know

 

 

All the best

Zeh

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The last one is not correct: when an iron ring increases temperature, both the inside as well as the outside diameter increases.

Is a nice experiment at highschool: copper sfere with a diameter slightly below the inner diameter of an copper ring. Sfere won't go through Heat the ring, and the sfere will fall through.

 

My guess is a more violent explosion as the powder heats.

 

Jan

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Daniel,

 

I also like your 'kebab' stick idea, to get the pricker and then the drill into tight spaces. I'll have to try that.

 

I'm also enjoying the 'drama' of your Victory build. :)

 

Incidentally, in his 'HMS Victory, Owner's Workshop Manual', Goodwin says that all 24 and 32 pdr guns were rigged with breeching and preventer ropes, due to their heavy recoil. Also that with a standard charge and rope restraints this could be up to 11'.

Edited by Stockholm tar
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Well I just made it through your complete log for the first time finally. Seems I keep getting part way through and losing my place...

I must say... What an Amazing and Facinating idea exchange and I love your trial by fire methodology Dr dafi.

 

On the guns... I have no clue.... but..... the guns would heat from within the barrel, toward the outer surface. Heat energy always transfers from hot to cold. The powder end would also heat faster then the barrel end as it would be more exposed to the reaction and for a longer time. I visualize the barrel bore becoming teardrop shaped as it heated, at least within the expansion rate of the cannons material at a given temp.

 

Thermally conductive substances such as metals usually transfer heat efficiently, unlike ...say... glass. Thats why a quick change in glass temp on one side causes breakage. The barrel overall, to my thinking at least, would expand radially from the center and more at the flint end.

 

In rocket fuel trials early on. there were early problems in uneven burn causing the launch to be throw off its center of mass causing wobble, which usually lead to mishaps (ie big BOOMS). On a cannon, the walls attempt to prevent this wobble, but as clearances expand the wobble would cause the recoil to be less symmetrical or straight back. A small shift of momentum to the left or right could increase the force on a single sides breeching rope, possibly to its breaking strength, hence a second rope picked up the slack. 

Symmetry of burn would also be critical. In an internal combustion engine the spark plug placement is key to maximizing efficency in torque and HP. Thats why Fords Boss 429 had a semi-hemispherical head and Mopars had a full Hemispherical head design. This forced the redesign of the plug placement in the valve cover center, but creates a more centered push on the piston top. In comparison the cannon has two issues... the flint fires on top (center of the back would be optimal) and the compression surface (ball) is not flat. If the burn reaches the top of the ball before the bottom, I can see a cannon recoiling with a downward thrust as the unsymmetrical burn would cause the ball to spin which could cause lift at the back wheels. Combined that with any side to side action and I'd want a preventer rope. To avoid these issues engines are build to be at tolerance when at temp, but this wouldn't work with cannon as the clearance would be to close on cold fightings.

 

Something I did notice, previously you had one of the breeching ropes wrapped araound the lower back of carraige, but not so in the most recent modification (I think the rings make sense, as some slack helps absorb recoil). That carriage wrap, to me, seems important as it would help force a more symetrical recoil

 

Of course this is all hypothesis and I could be completely mad.

 

Oh and in the entranceway doors. You forgot Pocket doors as an option  :dancetl6: or possibly DeLorean-esk gull-wing doors.....

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Thank you all for your input! Very appreciated :-)

 

Next cleared up the breeching ropes on both sides ...

 

Victory-131019_1224.jpg

 

... especially the loop ...

 

Victory-131019_1228.jpg

 

... and also looked at both sides that the ropes won´t be stuck underneath the wheels.

 

Victory-131019_1226.jpg

 

Then checked the length ...

 

Victory-131019_1223.jpg

 

... and Jan was right, here comes Captain Hook ...

 

Victory-131019_1233.jpg

 

... and have him installed in all his glory.

 

Victory-131019_1235.jpg

 

Victory-131019_1247.jpg

 

Victory-131019_1244.jpg

 

XXXDAn

Edited by dafi
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Is that beast dead or merely sleeping?   Oh... it's flynot a parrot.  Nevermind. 

 

Good to read that you've solved the preventer rope mystery. 

 

At first I thought the "hot guns jumping and recoiling" was a bit of literary license on part of some authors.  But then, I remembered seeing some videos of American Civil War (aka, The Recent Unpleasantness) where the gunners were firing for effect (load as fast as they could).  I believe it was a competition to get 10 rounds off, points for speed and accuracy.  Last several shots made those cannon jump also. 

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Thank you Sirs!

 

And next Dr Tentakels wild cousins went too into the trap :-)

 

Victory-131027_1265.jpg

 

But then dafi got trapped himself ...

 

... to much flue - too much nice substances - and forgot on the left hand gun to lead the breeching rope through the big guidance rings on the side of the carriage ...

 

... where both red squares are , gun well glued, breeching ropes well fixed on the hull ...

 

... okokokokok, hard way, means taking the guidance ring out, opening it, putting around the breeching rope, refixing in the eyebolt and reclosing the ring ...

 

... everything in there, deep-deep-down inside the bowels of the Vic ...

 

... tight, dark, but luckily not steamy ...

 

... and somehow managed to fix and even the picture looks ok :-)

 

XXXDAn

Edited by dafi
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I made them both for the same length, respecting some a tad shorter if fixed on the hanging knee :-)

 

The given dimension is three times the length of the barrel, and this really is just about the right length as I could see on the model. Both have the same diameter.

 

The positioning of the ring on the side is very clever, as it keeps the rope clear of the hind wheels. But even with both ropes I managed to find an arrangement, where both ropes can be kept clear of each other and the wheels, as looping around the back of the truck or fouling the wheels would have had very unwanted effects ...

 

XXXDAn

Edited by dafi
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