FastGun SMS Derfflinger

Discussion in 'From Stem to Stern: Warships In Detail' started by NickMyers, Oct 10, 2015.

  1. NickMyers

    NickMyers Admin RCWC Staff

    Nov 15, 2007
    Federal Way, WA
    Derfflinger class battlecruiser
    WW1 German
    IRCWCC spec: 24 seconds / 100 ft; 4.5 units

    This was my first warship build, and as such, it has some flaws, some of which have been addressed, and some of which will probably be never addressed. I do not hold it up as a paragon of shipbuilding, it is in fact, a flawed ship, but it is a very reliable ship and battles well.

    As it is 4.5 units, I have opted for a 'more guns is better' philosophy, and run with 4 guns - dual sterns in D turret and sidemounts in B and C turrets, leaving myself with but a half unit pump. Strategy wise, this means I cannot wade into the fray and trade sidemount fire. In effect, this means you must play as a super-cruiser: wicked stern guns w\ sidemounts of when you have a golden opportunity.

    We shall begin with the overview
    overview - bow.jpg
    overview - mid.jpg
    overview - stern.jpg
    You can rapidly note that I'm missing a few cupolas on the port side here. Our local North Carolina's have been interested in testing the durability of my topside elements this year. You might also note that my forward superstructure is missing the armored con, and is otherwise incorrect for the Derfflinger. I was halfway through building it according to plans when I realized that Derfflinger had a simpler arrangement, and did not remove the extra bits and did not get around to building the rest.

    My guns all have fixed wooden blocks holding the barrels for a steady firing position.
    I fly red flags in every battle and am always on the flagged team. Just part of the bravado. Derf has flown a red flag in every battle it has been in.
    Poking out of the forward stack you can see a little float. It is tied off on about 8 ft of line inside the super. You might be able to pull the ship up by it, but I don't think that would end well, its job is purely to mark the location in murky water.

    You should be able to quickly note here one reason the Derfflinger can be so successful despite its length: it has very little area exposed above the waterline.
    Fore&Aft she sports armor belts if you choose to model them (I did) - these have saved me from a lot of damage
    belt-bow-detail.jpg belt-bow.jpg belt-stern-detail.jpg belt-stern.jpg

    For props I use two 1.5" 4 blade props, one here has a blade broken off, and typically there are a pair of 1.5" drag discs on either side, with a dummy prop abutting them for looks. 2 battles ago I got tangled up with an Invincible whose drags hang too far off the side and actually lost my starboard set. The port set got bent around and half torn off a few weeks ago at the Seattle Mini Maker Fair.

    My main shaft stuffing tubes were originally the telescoping brass that is so common in the hobby. After 2 years both had been dented, bent, or otherwise damaged, so with the help of @Hovey they were cut out and we replaced them with some serious stainless steel tubes with oilite bushings. No more bending problems.
    The rudder is a 2 in-a-line (tandem) arrangement. IRCWCC rules state that they both must be operational, so the forward one is a tiny little stub while the after rudder gets all the size. The IRCWCC rules do not prohibit horizontal features, and so I have small ones on here. They may help a small amount. I've never spent much time playing with rudder combinations on this particular ship.

    Deck hold downs are machine screws, soldered on to wingnuts, which are in turn run down into blind teenuts in the subdeck.
    I use a cordless screwdriver for quick and easy access and closing pond-side.
    If the batteries fail me or I forget to bring it, I can still easily work them by hand thanks to the wingnuts.

    A, B and C turret covers are all 3d printed ABS. D is my last remaining resin cast. All covers are mounted on PVC knockout plugs, with material removed as needed. The plugs grip the PVC barbettes readily enough but are easily removable from them for gun access.
    In the stern I have plugged the inside of D with blue poster putty to reduce the ingress of water.
    All live barrels are stainless steel and are sleeved with clear tubing to protect vs incoming fire. Dummy barrels are thick walled brass and also sleeved for consistency and because I like them better not looking like a brassy moonscape.
    WillCover likes this.
  2. NickMyers

    NickMyers Admin RCWC Staff

    Nov 15, 2007
    Federal Way, WA
    Below decks...
    I used to have a coil gun in the the B turret, but had consistent troubles with it. This abomination was a 2am 'I'm tired of messing with this' solution. Basically this is a straight magazine with the middle replaced by a length of tygon tubing. a little plumbers putty and a tightly cinched zip tie on each end and it holds pressure well enough to fire hard.

    I use a 9oz bottle, which is 2-3 times more than I actually need, but I have the space and its light. The most forward thing in the ship is the lightweight aluminum regulator. The neck of the bottle sets in a cradle that angles it such that liquid co2 will not be passed into the regulator. There is a block at the bottom of the bottle to ensure it cannot slip out of position. You can see the solenoid for the forward sidemount here, fed from a Y off the main line.

    Blast shielding/internal armor is provided by the grey PVC shower liner. It is hung on hooks extended from the subdeck so that it can be removed if you need better access to the backside of the balsa.

    You can also see here an aluminum cross member. This is a piece of angle aluminum. I bought the hull from someone else who had installed a subdeck already, that subdeck is what you see here (sans aluminum crossmembers) - essentially two pieces of wood on either side joined by glue/epoxy at fore and aft by small pieces of 1/8" at deck level. In retrospect I would have been happier removing that and putting in a one-piece subdeck. Lessons learned. If I keep this ship for a few more years, I may yet do that.

    Moving amidships...
    Below you can note that I am not prone to neatly routing my wiring. Visible here from is a mess of brightly color connectors hookign to a breadboard - these are all the solenoid wiring, heading into the board where their flyback diodes are located. To the right of that you can see my radio box, above which lies my 45A mtroniks viper marine ESC, and below the radio box you can jsut make out the heatsinks of my pump ESC, a random plane ESC I picked up. Right of the box is the solenoid for the C turret sidemount, and you can also see the fill ports for the dual sterns. You should also be able to see in this picture that I favor bussing my power together rather than making a a large number of joins at connectors.
    Originally built to mount 2 6v 12 AH SLA bricks, these lovely aluminum angle battery trays will conveniently also fit LiFePO4 20AH blocks, which is what I have been running this year.
    I wired up battery harnesses and then scotchkoted the terminals to prevent them from being shorted on the battery trays.

    A closer look at the electronics...
    The flyback diodes...
    I could probably do away with this all together, or greatly simplify it by moving the diodes elsewhere, but I'm a bit stubborn and I don't have problems with my solenoids, so I'm not messing with it. Besides, it gives @Hovey and @Maxspin something to make fun of besides my half unit pump. It is also not a very pretty solder job

    My radio box has at first glance a lot of penetrations, but most of these wires are actually not penetrating. From the inside I have a single penetration each for + and - servo power which is bussed to other servo channels that need it. Each of throttle, rudder, and pump have a penetration for Signal. There is a 1/8" piece of ply adhered to the surface of the box to provide more thickness, then thru-holes were drilled, followed by a pressfit copper pin, to which wiring was soldered. Either side of a set of pins is the correct half of a servo lead. There are 4 more penetrations for the source power for the solenoids and 3 switched lines to control them. The whole affair is scotchkoted on the outside to seal against moisture ingress.
    My receiver is taped to the upper side of the box, one more little thing. If a little moisture does seep in through the box seal, it is less likely to reach it in its lofty perch than if it was sitting in the basin on the box. The antenna are taped out of the way.
    I'm using microswitches, at the time it was a concession to save a little coin. Now I'm just sticking with them because they're there and they work.
    Generally I minimize the number of times I open my box, the avoid getting debris into the sealing area and to prevent any of those 'well that was stupid' moments that so often involve liquids.

    This box is not technically rated for immersion, so I will probably be scotchkoting this RX this winter. Its predecessor was.

    My pump ESC had a horrid heatsink design, esentially two thin pieces of aluminum with a very poor thermal adhesive between it and various chips. I replaced that with a copious amount of copper and a much better thermal adhesive. It is overkill. The ESC itself was then slathered in scotchkote, as is my preference.
    As part of my winter maintenance, the scotchkote around the wires will get cleaned up and reapplied.
    Notice color coded connectors at work - blue is for pump. I really like powerpole connectors for any ship that has the internal space.
    Panzer likes this.
  3. NickMyers

    NickMyers Admin RCWC Staff

    Nov 15, 2007
    Federal Way, WA
    On to the stern!
    Motors and pumps and guns and more! This is where the action is, and it certainly shows when trying to fit everything in.

    This is the underside of the stern deck plate. You can see the dual stern mags, with wrapping to protect against marauding things that make dents, the coil in C, and the cutout for the top of the pump motor to fit. Yo ucan also see the pump outlet line, which is annoyingly connected to the deck, making working in the backend of this ship that much harder. I need to remedy that.

    Drive motors. A pair of Mabuchi 550s, exact RPM @ 6V I don't recall. Theyre hooked up to Traxxas villain gearboxes, into which my industrial grade stainless steel stuffing tubes are slid.
    You can also see the 2 accumulator tanks for ready-air for my dual sterns, a piece of foam that reduces the debris reaching the pump, the pump well stands empty in this photo as the pump has been lifted away with the stern deck. You can also see the two fuse holders, one for each motor. I like my motors fused individually. I'm odd like that, it works for me. I also do not solder wires directly to my motors, instead using female spade terminals to slide on, thus I can swap out motors pondside in a hurry if needed. My pump is wired the same way, using flag terminals for a 90degree fitting.

    Below can be seen the twin solenoids for the dual sterns, and the rudder servo, currently a HobbyKing 'waterproof' servo, which is probably no more waterproof than the Traxxas one it replaced, but a good deal cheaper. The bbs are clustered around a magnet epoxied into my waterchannel. I have several placed through the channel to collect loose shot.

    The rudder gears are from ServoCity, as are the hubs they mount on. The excessively stout pushrod is another item that is overkill. I bought the proper hardware to redo it 'right', but why fix what works? The gearing ratio is such that with the Traxxas servos and their terrible throw I still get enough movement, but with the HobbyKing and its full range of throw, I actually have to dial down the throw to about 50% on the radio.
    Panzer, Beaver and Tugboat like this.
  4. Captain obvious

    Captain obvious Active Member

    Jul 19, 2016
    Hastings, MI
    Nice, Thank you for sharing.