(My Fantasque in the foreground, with Ben Lee's HMS Cossack in the back ground, at the North American Big Gun Open (NABGO), on July 12th of this year) Just a few musings from a hardcore Big Gun destroyer captain... Destroyers are challenging to build, engineer and campaign. In practical terms, they are the smallest combat warships, in terms of displacement, in either Fast Gun or Big Gun. They are not for rookies, either in terms of engineering or operation. Destroyers, by design, are long and slender, designed for speed. They are not very good in turn fights, as a rule, but if you can build a fast destoyer, you can use its speed to your advantage. I run a Fantasque, a member of the "Terrible" class of French "super destroyers." These were large destoyers (3' long in 1:144 scale), and the fastest destroyers ever built, even to this day (46 knots top speed). This class also carried mines and torpedoes. Mine currently has twin torpedoes mounted on each side, but I have tripple tubes waiting to be installed. Because destroyers have such small displacement, there are some very real challenges the captain must overcome in order to be successful. Some of these are: Inherently unstable, which means that very part and piece has to be weigned and carefully placed for stability. Very limited hull capacity for air and equipment, so they can't take much hull damage, and they are prone to sinking if the captian isn't extremely careful (and lucky). Because space and weight allowances sre limited, there are few options for armament. Also because space and weight allowances are limited, there are few options for batteries and motors. With those limitations, it's very difficult to get a destroyer such as the Fantasque up to its top speed, and to keep it there for any length of time. A slow destroyer is a sitting duck. Because of the same space and weight limitations, every piece of onboard equipment must be miniature in size, which often means expensive, with limited choices. You may need to make your own pump, for example, and your guns or torpedoes may need to be custom built to fit in the hull. OK, so much for the challenges. Destroyers can be a lot of fun to build, engineer and campaign, if you can minimize the weight and "footprint" of the onboard equipment, and if you can keep the speed up, and if you can learn how to hit and run. A destroyer can be launched and retrieved with one hand, and can be shipped as luggage on an airliner. (The Fantasque in the photo was checked as luggage, to and from NABGO.) Destroyers don't need much storage or bench space, and they look pretty cool, too. Rob Wood Visit this site Combat ready: le Fantasque DKM Lutzow USS Cimarron (fleet oiler) LST 325 On the ways: DKM Bismarck PT 109
Thanks for the compliments! Both of the destroyers in the photo use loose-cell battery holders, with 6 AA NiMH 2700 mAh Lenmar batteries, for a total of 7.2 volts. Both destroyers run at around 37 knots with that setup, and will run at top speed for over 30 minutes. Ben and I have done a lot of experimenting with battery/motor pairings, looking for the perfect combination, and I believe Ben is satisfied with his setup, since the Cossak's top speed was around 37 knots. For my Fantasque, however, I'm still looking for sustained 46 knots. I have two new motors installed right now, and will be doing sea trials on Sunday, so we'll see.
looks like she is armed only with torpedos. Have you come up with a way to arm the main batteries as well? I have a Mogador that I have been working on for some time now. I have found some very small, Hi rpm and hi tor motors that run on only 9 volts. with those installed I will have displacement to arm a turret or two.
um working on a Scipione Africno (Capatini Romani)um at 4.5 lb with all the stuff in and i still have 1 lb to go .so un looking to add more battery
I'm not certain whether or not your Mogador is Big Gun or Fast Gun, but a Mogador has about 10% more displacement than the Fantasque, and as I have quite a bit of lead for ballast, I'm thinking that, if you're careful, you should be able to arm the two forward guns in a Mogador, as well as arm torpedoes. It really depends upon how much overall weight you're carrying, and how it's distributed. Over the past few years, I've experimented and replaced larger, heavier equipment with smaller, lighter versions, in hopes of building up enough "ballast credit" to arm a gun or two. I have the credit now, but the big problem is space for increased gas supply and, in the case of a couple of bb guns, ammo, the guns, and plumbing. I'm not sure in my case that adding a couple of bb guns would be worth the effort, since the 1/4" torps carry a pretty nice punch. One bit of technology that really needs development in the Big Gun sector is centralized CO2 supply. We have it in the form of regulators and bottles (or disposable canisters, in the case of my Fantasque), but we still have separate accumulators for each gun (or pair of guns). I've been working with Dave Seibel in my club to develop a set of triple torps (left and right) for my Lutzow, with a shared accumulator. Since we ordinarily don't use more than one accumulator at a time, the obvious efficient solution would be to use a centralized accumulator, and tap it for whatever weapon we want to fire. My prototype is functioning, but still needs some leak management to make it combat ready.
In your case, I'd definitely be looking at a 10-c (or better) 6v or 7.2v sub-c racing pack. There should be plenty of room available for that, and the weight allowance is more than sufficient.
Rob, Very nice write up and ship!! Looks real nice. I see you have a PT boat under construction. Now thats a challange!!
its fast gun and my is battery 9.6 racing pack and one gun http://www.rcnavalcombat.com/FileManager/Storage/633526131461662500.png its a dark but the only picture i have rite now
Thanks! I'm getting a little carried away with detailing on the destroyer, though, but I just wanted to spiff it up. You can't see Ben's Cossack too well in the background, but he's got very detailed ships, and at the same time, they're also very respectable combat boats. He's a true inspiration! The PT boat is sort of like the Holy Grail for 1:144 miniaturization fanatics. I've got it running and steerable, but there's a long way to go to make it capable of doing any damage.
about 40 mins. then it slows down i mite go with 2 9.6 batterys but i dont no yet open for any battery 2.lb or less
There are several reasons why the battery might run down after 40 minutes. One (of course) is that the battery simply doesn't have enough indicated amperage to do what you're wanting it to do, and another is that the battery is worn out. Before adding the weight of a second battery, you might consider replacing the pack with another 9.6v pack with a higher amp rating.
this is what i have i pick it up at raidoshack Ni-MH 9.6V battery pack. One 9.6V, 1600mAh Ni-Cd battery pack jest to get started i also have 2 of these http://www.radioshack.com/product/index.jsp?productId=2102827&cp=&sr=1&origkw=motor&kw=motor&parentPage=search so do i need help
A few more questions to help me get the whole picture: 1. Do you have a pump? 2. Are you getting the speed you want, even though the battery lasts for only 40 minutes? 3. How much running time have the motors had? 4. Are you running your prop from a gearbox, or is it direct drive? 5. How is the prop shaft connected to the motor or gearbox? Are you using dogbones, or some other method? 6. Are your props both easy to spin by hand, or does one (or both) seem a bit stiff? 7. Can you send me a link to details about the battery pack?
1 yes 2 yes 3 new 4 direct drive 5 dogbones 6 easy to spin 7 http://www.radioshack.com/sm-buy-the-rc-car-battery-pack-and-charger-on-http--pi-2103206.html
OK, here's happiness: http://www.all-battery.com/index.asp?PageAction=VIEWCATS&Category=186 Pick any MiMH battery pack on this page, live long and prosper. You can almost triple your running time with a 4500, or more than double it with a 3600 or a 3800. Leave everything else in your boat the same. That's my advice, and I'm sticking to it.
sweet thank you i figured it out to day when i look back on the topic and saw 2700 mAh . so the more the better .thank you for happiness site my Destroyer is about 120 days from battle .still dont know what to go with popit or Solenoid have both whats better on co2
Batteries are rated by voltage (in this case, 9.6 volts), and by amperage, which is the actual stored energy in the battery, and is also referred to as the capacity of the battery. Think of the battery as a fuel tank, if it helps to understand it, since we are literally draining the "fuel" (capacity) from it as we run propulsion motors, pump motors and servo motors. Each of these motors "draws" (drains) amperage from the battery, according to its size, the amount of work it is doing, and - most important - the efficiency at which it operates. Cheap motors tend to draw more amps, because of the poor quality of the materials they're made from, the number of windings, and the way they are constructed. I personally believe in spending a little more for motors, just to increase that efficiency, because the combined total of draw of all of the various motors determines how long you run, how fast you run, and how big of a battery you need to have. But that's me. When you look at one of the small batteries we use, whether NiCad or NiMH, you will usually see the capacity (amperage) rating on the side, measured in mAh, as in 2700 mAh. mAh stands for "milliamp hour." A milliamp is 1/1000 of an amp. One thousand milliamps = 1 amp, and 1000 milliamp hours = one amp hour, which means you can draw a total of one amp for an entire hour. 2700 mAh on the side of a battery pack means, in a perfectly charged, perfect world, that you can draw 2.7 amps for one hour. So, strictly from a math point of view, if you had a couple of propulsion motors that each drew one amp as they drove one prop each on the pond, a couple of small servos that you used occasionally (rudder and firing valves), a small pump and your receiver, you could conceivably run the entire boat for about an hour with that 2700 mAh pack. But that's in a perfect world. In actual operation, sticking linkages, unlubricated prop shafts, misaligned couplers between the motors and shafts, dirt and corrosion on contacts and connectors, cheap motors and weeds on the pond, all combine to rob you of capacity. So, even though your math tells you that you ought to be able to run at full speed for an hour, you might find that you are only running at about 50% efficiency, and are therefore only getting 30 minutes of top performance out of your pack. Your choices then are to increase the efficiency of your onboard equipment, and clean the weeds out of your pond, or increase the capacity of your power source. That usually means a larger battery pack, but at the same voltage as your smaller capacity pack. It's really important to do regular maintenance, which includes cleaning, lubrication of all onboard mechanical devices wherever friction is likely, checking to see that you haven't damaged or bent linkages, therefore making your motors work harder, replacing equipment that doesn't operate smoothly and steadily, and to also use the best equipment you can afford. If you don't follow a pretty rigid maintenance checklist, you might consider it, and following it religiously. If not, increasing the capacity of your battery pack will only be a temporary solution. It's the sum total of the battery pack capacity, the careful charging of the pack, the types of wire and connectors you use, and the quality and health of all of your equipment combined that makes the difference between a thoroughbred and a defenseless garbage scow out on the pond. By the way, I forgot to ask you: How do you run your receiver on 9.6 volts? They're only rated for 6 volts. Do you use an ESC? To answer your question about poppet valve vs solenoid, it's purely a subjective choice. A solenoid valve is theoretically more efficient than a poppet valve, because it eliminates a servo and mechanical poppet valve pair, but I see people having problems with reliability with both approaches. The best way to approach it is to talk to guys in your club (assuming you're in a club), and see what setup they're using.
