R/C Naval Combat

There are also these polayacene batteries:

http://www.goldmine-elec-products.com/prodinfo.asp?number=G13133A

I'm not too familiar with their technology or its environmental issues.

They list the diameter as 9.3mm which is a little too large, but I don't know if that includes the tabs on them.

a cap will discharge no faster than the resistance across it allows (or using a dead short, its internal resistance). they do have the ability to discharge quickly. Just like your sub-C's have the ability to discharge at 50-100 A or more but we only pull a couple out...

The springs I found were based on storing the approximately 4 calculated by john stored in a 1/4" projectile ball bearing...

quote:

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Originally posted by archer183

a cap will discharge no faster than the resistance across it allows (or using a dead short, its internal resistance). they do have the ability to discharge quickly. Just like your sub-C's have the ability to discharge at 50-100 A or more but we only pull a couple out...

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True, but don't caps generate a ton of voltage if left by themselves w/ no battery? Therefore the current will spike?

Someone with time & an o-scope?

the problem we have with a cap is that the stored energy is proportional to the capacitance times the square of the voltage... this means that if we try to pull a constant power output, the voltage will decrease rapidly, unlike a battery which will have a relatively flat discharge curve after the initial startup time.

The cap, on the other hand,if we maintain a fixed resistance to discharge through, we get an exponential decay for the voltage... which means a rapidly dropping off power after the initial launch... very hard to maintain a constant speed.

We have another issue... weight.

I was cutting brass tubing last night, getting ready to build a crude test torp, only to find that a hollow brass tube with ends plugged sinks like a stone.

The piece of tubing was 9/32" OD and 4.5" long, about the size I'm thinking for an average 1/72 scale torp.

Am I incorrect in thinking trapped air would make it more buoyant than any kind of floating material (foam, wood)?

I think that means we are going to have to explore lighter materials in construction... keeping the amount of non buoyant materials to the absolute minimum.

Which brings me back to my resin casting idea. If we cast as many parts in some kind of plastic, we should be able to keep the weight down.

I still like my idea of permanently casting the pager motor into the back of the torpedo body. I'm envisioning a 3 piece torpedo: the rear section has the pager motor cast in place and already has the fins attached, the rear section attaches to a center section (perhaps with a balsa wood core) that holds the battery/capacitor, and then the front section containing a warhead also attaches to the center.

yes, trapped air is better than foam. Here is a good test for you. Weigh your torp. then figure out the volume it takes up (if it is tube, that should be easy). Calculate the weight of water if that volume were made out of water. the difference (assuming that the torp with air weighs less) is the buoyant force

check out www.mcmaster.com for rigid thin wall plastic tube.

I just picked up some .47Farad, 5.5V caps (yes, I said 0.47 Farad) to play with.

Archer183,

Where did you find those caps?

In the scrap bin at work. They are a bit big at .8IN diameter, 0.3IN thick. You might check out the electronic goldmine or allelectronics (google)

You all might have a look at these clear packing tubes at mcmaster, they come in several suitable diameters and 4ft lengths.

OD Part # Cost (ea.)
0.28" 2044T41 0.66
0.40" 2044T42 0.86
0.53" 2044T43 1.14
0.70" 2044T44 1.29
0.79" 2044T45 1.43
0.93" 2044T46 1.71

There are also fluorescent light bulb safety shields that I'll be using. They come in 1" and 1 1/2" OD in various translucent colors. mcmaster catalog pg 680.

-iamscottym

i havent really been following this topic for a while, has anyone gotten to actually make a torpedo yet, or is everyone still working on the design? It will be a bittersweet moment, when a good captain fields good torpedos for the first time, a sad day for rookies like me.

I'm just waiting on parts. I ordered props from hobby lobby and some 400 size motors I've got laying around in a 1" FTC. An atmega 8bit micro and cheap gws esc will drive it on a 7.2V 1300mAh li-ion. I'm going to try static fins first and then play with gyros and servo actuated fins. A long lexan water tank would be really helpful about now!

Wow, i hardly understood a word you said. Good luck, it sounds like its coming along nicely, cant wait to see more on this.

don't worry too much about it.. it is probably at least a year away from anything even remotely reliable and useful and small enough... right now, several folks are working on just getting something going to prove out various aspects of the various designs.

Well, im still a year or so from getting my ship on the water, but i dont think they allow these in the IRCWCC, right? i would be saved then.

Boomer,

You don't have to worry, its unlikely that locomotive torps will be allowed in more than a few (if any) current clubs. Us torp guys have our eyes on the future...

Hope for the best and prepare for the worst. I am sure that some more clubs will realize that working subs and torpedoes will add even more depth to the hobby.

moved to other thread :)

Very true, this is a very interesting concept, and being a reality will be very nice. I personally wont build a sub, not enough interest, bet remember "know your allies well, know your enemies better". And yes, lots of issues, but to any innovative person, it will just be another cat-and-mouse game. I wouldnt mind a change in the ship lists, the speed charts are toosimple, and dont really accomadate for actual ships. But torpedos will be an interesting sight to behold.

Just to make sure this thread stays open as the "tech" thread on torps,

Lets continue to discuss tactics and rule changes on the original "Official Torpedo Thread" in the Next Gen Combat section.

Sure!

Let's have Justin relocate the off topic posts


Mike