The History
The Düsseldorf fire-fighting boat was developed and built by the Rheinwerft company of Mainz-Mombach, and it is operated in the Ruhr industrial region of Germany. The vessel is designed specifically to cope with disaster situations, such as a ship on fire, a major oil leak or a harbor system in danger of explosion, and its fire monitors, operating at a pressure of 10.5 bar, can hurl water or foam 145 feet high and a distance of up to 310 feet. The two V-12 engines produce a total of 930 kW (1260 BHP), giving the boat a maximum speed of around 23 mph.

The Model
The Romarin kit of the Düsseldorf fire-fighting boat is large and capacious enough to accommodate all the equipment required to emulate the wide-ranging facilities of the full-size vessel. Optional working systems include the fire monitors, crane, anchor winch, radar, searchlights, blue light, horn and siren, and also the sound of the diesel engines. The plastic hull is moulded in thick-walled material, and it offers plenty of space for the numerous mechanical and electronic parts required for the auxiliary working systems. The model is propelled by two proven MAX Gear power systems, giving it an impressive turn of speed. Four large rudders guarantee extreme maneuvering capability both forwards and astern. The fire monitors can be swiveled horizontally and vertically from the transmitter, and with the recommended electric geared pump they can fire a jet of water a distance of 20 feet. If a working boat crane is fitted, the vacuum-moulded rowing board can be raised, swung outboard and lowered to the water in true scale style.

The TD SR12 receiver is equipped with a triple antenna (2×2.4G & 1×900M) design that provides multi-directional wide coverage for the remote signal and is designed for RC users who want to benefit from resilience and long-range in their radio communications.
TD SR12 also provides a socket that can be used to connect the NFC Switch panel to enable the built-in Power Switch function. Dual-power provides a safe and efficient way to power the system with your power sources connected via a pair of standard XT30 connections. The dual-power consumption system is designed to operate in balance mode, where it consumes the power line from either power source depending on which has the higher voltage. With a built-in black box module, the data (Power & Signal related) under unusual status during the flight can be recorded by TD receivers.
The configurable 12-channel ports are a big feature of TD SR12, each channel port can be assigned as PWM, SBUS, FBUS, or S.Port. With the FBUS protocol, the Tandem series receivers can open up the possibility of seamlessly pairing with multiple telemetry devices (Neuron ESC, Advance Sensors, etc.) as well as simplifying the builds setup.

I like the new motor, it has a higher voltage rating than the Graupner 400 which is 6 volts.

I trial fitted a thermal switch to the fans in the dummy motor, which is mounted on the 540 motor. It starts the dual fans at 30deg C and switches off at around 20deg C. Bit hard to hear in the vid (plus the YT transfer removed the middle of the vid, -there was a gap before I put the soldering iron on again,- and at the end don't know why it does this, - doesn't like the format I think😠) Anyhoo, not doing it 3 times! (clipped the end 10 secs off the previous try as well😠)

Fan switch is powered at 8v via a small voltage reg from the main battery (3s 2200 20c) and works pretty well. All fully hortomatic like😊

A bit more refinement on the timing but getting there. Finally got the voltage regs from China to complete the system. A bit noisy, as the water pump is dry,- quietens down with water. Switches in stages using Grahams magic timer, - 1. smoke on, 2. water and air on. There is actually smoke running constantly at a reduced level once everything is running, but very hard to film. I could turn it up but I don't want it to look like it's on fire😂

Had a large moment of enthusiasm yesterday and fitted the jet unit and associated bits. Then it was time to wet its bum for a test. First off, the jet wouldn't suck water without pushing the stern down slightly, (as I expected due to the boats' light weight.) I added 300g to the stern and she was away😊 Happiness filled I were😁!. Reversing bucket works very well (even though it's a bit of a blob on the transom). You really need one if you don't want to go forward forever, trying not to 'sail yourself into a corner'.

I Need to waterproof the pushrod holes in the transom but the bellows I bought are too stiff and compress too much, so I'll have to come up with another method, (probably some deflectors for a start. Only a problem when in reverse with a bit of throttle on. Plenty of power with the 2s I was using, but motor is rated 12-24v so it would scream, -even with a 3s. I'll start with 2s and see how it goes. Might have an initial blast on the lake this week if all goes well, although I'd like to finish the deck bits first.

Just waiting for some Voltage regs to come so I can complete the electrical side with the fancy bits.. The mechanical and electrical sides are as good as done, Grahams timer is working perfectly, with the water pump and air pumps hooked up (going to install a VReg on each one plus the smoker).

Working on this idea for a bit more refinement on the exhaust smoke idea. Graham mentioned these timers were worth a look, so I purchased a few from Ali Express for about 90c each. They work well for an off/on set-up but not quite as well for an on/off set-up. They are variable from 0-12 secs and have a lot of possible uses. I was trying for a puff of smoke at start-up (which in my application works in conjunction with the twin sound units (HSL and ST) and this initial test seems to work ok (bit of refinement with timing and air pump speed required yet). Already have the smoke going well but there's always a little morsel to add (ref Mr Creosote)

I'll be using the small 5A voltage regulating bucks in the models (the ones shown are just for testing) with one 2s LiPo running 2 regs,- one for pump, and one through the timer for the smoke pen. You can see the timer working with no input from the TX in the vid, When fitted, both will be switched on/off simultaneously with the solenoid 'latching' power on/off, circuit (thanks to Graham for the layout) using the left stick.
JB

Think I've finally sorted the mixing smoke and water for exhausts problem. Graham has already done his using the same pen / e-cig unit but with some nice electronic controls for the on off system, but not having the electronic abilities I've just gone with a more basic method. Wired up the pen and installed a filler tube (2 tubes are better - one for a breather) these are capped after filling to prevent air getting back from the pump. This system has a water pump, an air pump and the smoke unit, (all adjustable with their own voltage buck) Thanks to Martin for his pen suggestion. I was previously using large capacity elements fitted in various containers for my experiments (truckloads of smoke available) but these pens are great for tight spaces and don't draw much current.

Air, and a small amount of the cooling water are mixed by venturis just short of the exits (the air pushing the smoke and blowing the water clear of the smoke tubes). I've fitted the same system into my ST but am still waiting for the air pump from China (postal system problem there, then Chinese new year holidays with new rules apparently) Get the odd bubble at rest but with the low exhaust you can't have everything.
Latest vid with boat in the tank.

JB

Hooked it up to test exhausts and set the voltage a bit higher (2.6v) to show a bit more smoke. It can go to 3.5V but the test V reg Buck wont handle it (I've fitted a fan but still gets hot quick on 3.6V although not quite as bad.)
JB

Still waiting for a better air pump so thought I'd try whacking 2 pumps on and upping the voltage from 2 to 2.5V Works a lot better but smoke still a bit slow. If I blow gently into the air tube I get massive clouds of smoke (hence the need for a better pump) Sorry about the crappy vid,- camera lens has a cloudy spot and not so good inside.
JB

Just trying a few more things while waiting for more bits to arrive. This time using a small ESC for the smoke, and using CH 6 (rotary pot) on the TX. Water is adjustable with the voltage reg but could be hooked to the motor ESC as well, with a voltage reg used to set max flow. I'm just using the Heng long smoker box (modified) for this test.

Found a way of pulsing the water using the pump of a dead smoker (Hen Long smoker that is) In this test I used a pump to prime the smoker pump (smoker pump on 2s) and the rest is just syphoning through the pump to the smoker. You can vary the amount of 'spitting' from the exhaust by running the pump at low voltage or maybe using a peristaltic pump with a small flow.

I did not connect the fan powered smoker unit as I ran out of silicone tube, but the result should be the same as the last vid but with 'spitting' water. Using the smoker pump for water is not perfect as it would need sealing properly, and it's cumbersome, but you will get the idea. I have ordered a couple of small air pumps, so might have another crack when they come. I'll use them at the exhaust to disrupt the water flow if they are powerful enough, rather than use the smoker pump.

Found a sound by accident which sounds quite a bit like the sound of the GM Detroit 453 2 stroke diesels fitted to this boat (still has these today) Vid from cockpit is the sound I discovered while mucking around with some old electric motors, and my new voltage controllers which just turned up.
I'll add the link to the real engine for comparison (next post here). Sounds to be revving really high but being 2 stroke it's only doing around 2800 rpm!

JB