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Revell Gato Class Submarine Conversion.

I am about to start the most ambitious project to date. This one will be running alongside the three others currently on the go, The Police Boat which is nearly completed, The Dusseldorf Fire Boat which is well underway and the PTB upgrade. My intention is to change this Revell model into a static dive radio controlled Submarine. I am lucky that Martin555 has agreed to help whenever I get stuck which will be invaluable since he has already almost completed the same. I started by purchasing the model from Amazon for less than £50. I have also purchased the water tight tube for the electronics. I will make the end caps and sealed internal plugs from some 80mm diameter nylon I had at work. It will now come in handy that I am a toolmaker and have a considerable array of machines at my disposal. I will turn the plugs next week and find suitable o rings. I have started to prepare the hull. There is an enormous amount of work required to adjust the standard kit. A lot of cutting and drilling. I have prepared the split lines and glued in the alignment pegs. I have ordered suitable shafts and from the USA. They should be here in a couple of weeks. Next job is to stick the two halves together and start the cutting.

5 years ago by MouldBuilder

Forum

Graupner Closing

Sad that their components will no longer be available - the geared motors sets - the outboard motors - - shafts etc etc etc . All very useful items to say nothing of the kits they produced. Wonder how much the closure will affect the model aircraft fraternity?????????

4 years ago by redpmg

Forum

Magnetic motors

Hi Martin, "This type of motor would be good if you could control the speed." Since the motor uses permanent magnets on both stator and rotor the speed will also be permanent and unalterable, as both magnetic fields are constant. To alter the speed of the vessel (or go astern!) you would need to alter the pitch of the prop and hence the thrust. 'Variable pitch !' This is the operating principle of constant speed turbo-prop aero engines for example. VP props are also used on many ships these days. Needs some intricate gearing built into the prop hub, and controlled by !? 🤔 Control shaft running inside a hollow prop shaft? Don't know of any model versions on the market so if you find one, or come up with a way to DIY one I'd be MOST interested.😉 A constant speed version driving a generator might be useful though👍 IF it has enough torque. Might work with a decent gearbox? Cheers, Doug 😎

5 years ago by RNinMunich

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Martin Westquay's Piper Cub ;-)

Hi Martin, most of us played with the Keil Kraft & Veron kits in our youth. The small kits fitted the pocket money slot very well - most succumbed early - have memories of Jetex units climbing away from your new model on their own - never to be found. Others succumbed to the force of a penny Ronden "Flash Bomb" lit on launch - spectacular. Then there were the larger kits - rubber powered built with fathers assistance - home carved - which flew out of sight - also never to be seen again. One climbed out on a thermal until a dot in the sky - turned up on a farm 20 miles away unscathed - always had name and address/phone no on a small card on the models.....Later the usual ED Bee's , Allan Mercury 1.5's etc . Watched a 40" span Piper of mine trying to take off with a friends clapped out Bee - ran the length of the rugby field and lifted just in time to intercept the posts............ Have 90% of the flying scale model plans - always mean to build one but designing and making commercial kids kits on the Laser intervenes. So far Land Rover series 1 , Defender, Suzuki SJ410 , Generic Jeep, Willys 1946 Jeep, Pitts Special , Tiger Moth and Eurocopter - all made with 3mm MDF - either fully designed or heavily modified by myself.

5 years ago by redpmg

Forum

Magnetic motors

I have been thinking with the idea of magnetic motors and trying to get away from normal . At the moment I am unable to spend much time in my little workshop (health reason) So I have had these crazy ideas buzzing around in my head. Normal this leads to me making something different. Martin.

5 years ago by Martin555

Forum

Propeller direction.

Hi DG, Thank you. It goes to prove that you are never to old to learn. I thought that there was a worldwide standard. Looking at the video it reminds me that I had some friends that worked with a cavitation tunnel, and they would never talk about there work there. Obviously we all were doing MOD work at the time. However it is interesting to see the different results that different have. Thank again. Martin.

5 years ago by Martin555

Response

Re: Joining the fuselage.

As the submarine does not have to move very fast and has two motors driving 35mm , does anybody have a suggestion on how many rpm the shafts need to go. I am sure that torque is more important than rpm but a forward speed of around walking pace should be enough. Your thoughts would be appreciated. Peter. BTW jb, the bow planes are in the kit, the actuating mechanism is the item I have to figure out.

5 years ago by MouldBuilder

Response

Re: Revell Gato Class Submarine Conversion.

Hi Bill. You have made a really nice looking model. This project will take a while but I am looking forward to it. The , shafts and joints can be found on ebay. The item number is 273490619808. The seller is rc-sub-workshop. They are a little expensive but they do come with all of the required parts. I will let you know what they are like when they arrive. They are coming from Hong Kong I think. Peter.😊

5 years ago by MouldBuilder

Forum

Prop size and speed

Hi, If you have a left hand and a right hand propeller then you will need to reverse one of the motors. As for I think that at the and of the day you will have to experiment to find out what suits your needs as you must remember that you are dealing with scale models and that the water it is on is not at the same scale. A 2-blade propeller produces two pressure pulses per revolution, whereas a 3-blade propeller will produce three smaller pulses per revolution for the same amount of total thrust. As a result, the 3-blade prop will be inherently smoother and therefore quieter. A 4-blade propeller can improve all those characteristics that make for practical, all-around boat performance. Four-blade props usually have a lower pitch to keep the rpms the same as a 3-blade. But are 4-Blades Slow? So, why might a 4-blade generally be slower than its 3-blade counterpart? To be honest, many 3-blade/4-blade speed comparisons are simply not fair. That’s because the respective in question are simply different styles, designed with different purposes in mind—different diameters, rakes, cupping, and blade shapes. If however, for comparison purposes, we take two , identical in design (blade shape, diameter, rake, cup, etc.) that are appropriate for a given application, and simply add a propeller blade, we get a truer representation of just where the difference lies. The addition of the extra blade causes increased drag, which, in turn, requires more horsepower, in order to achieve the same rpm. Since the horsepower is limited, the rpms drop, and the speed will tend to drop with it. This is why, when going from a 3-blade to a 4-blade, the pitch is dropped an inch, or more, in order to keep rpm parity. It is this difference in pitch that causes any potential speed differentials between the 3-blade and the 4. I don't know if this will help you but this is a complex subject and you could get your self totally bogged down with all of the theory. Martin.

5 years ago by Martin555

Blog

WTC/Sub Driver.

Hi Guys, Just a little update on the home made WTC. Tested in Bug Blue, I had to add a little weight under the tube and held it there with elastic bands. It floated level so I submerged and surfaced it quite a few times and worked fine.(no leeks) But the battery on charge until fully charged. Unfortunately when I temporarily fitted it in my Gato and connected the universal joints to the prop shafts, then I ran both forward and reverse slowly at first then at full rev’s, it sounded like a cement mixer full of rocks and extremely loud. So I switched it all off had a cup of Coffee then went back to it , I switched it on but nothing happened. I have had a quick look at it and the battery and fuse is ok. (I suspect the remote switch) I will have to open it up to investigate further but I am doing other things that the moment so as soon as I get the chance I will. One of the photos is the WTC on the surface the other submerged, you can see in the submerged photo the ballast party balloon full of water. Martin.

5 years ago by Martin555

Forum

Tamar Lifeboat

Hi Want to change to brass on Model Slipway 1/16 Tamar Lifeboat. Lost one of the original plastic propeller supplied in kit , and looking at Roboesch 40mm brass as replacements . Not sure whether to go for 3 or 4 blades and type A or C Type props. Good speed from the supplied props with kit running with brushless Tornado 3536 1050kv on 3s lipo. Any recommendations of what to go for would be helpful. Thanks

5 years ago by alan50

Forum

Tug towing

The Decaperm 6v geared is 1:2.75. And very high torque, so it ought to swing a pretty big prop. Measure the prop diameter when you get home as well, also the number of blades. Have you considered experimenting with different ? That can radically change a boat's performance with little effort. Props can be expensive, but you can buy a few cheap ones, or borrow some from a club colleague for experiment. Either increase the diameter or the pitch (or both!) if possible, or go for a 4-bladed one rather than 3-bladed.... I don't know about a Kv/torque relationship - the key distinction is inrunner (high speed/low torque) vs outrunner (high torque/lower speed). Although that is a very general statement, and almost certainly untrue for some motors. KV is a measure of how many revs per volt you can expect. So an 800KV would give you 4800 revs at 6v - not a lot, though that depends on the prop, of course. I normally go for around 1000Kv, and run at 7.2v. Voltage is important for a brushed motor - the brush gear is designed for a particular voltage and will wear badly with increased volts. Brushless do not have this problem, and can run on a wide variety of voltages. Running at 24v is quite possible... The ESC you want for a brushless is simply one that can handle the maximum current your motor will draw - which you can either look up or measure with a Watt Meter. The key concern I usually have with brushless motors is thermal. They are normally designed for aircraft use, where they will get lots of air cooling, and we are putting them in sealed enclosures. Unless you want to water cool, I would suggest running a brushless well down below maximum power, to keep the temperature down. So overspec it, or run with a lower than maximum voltage...

5 years ago by DodgyGeezer

Forum

Motor, speed controller

All got off ebay. The drone boys use this sort of thing extensively. Go there and google the items below. I have added approximate current prices - but I can recall getting some items considerably cheaper.... FPV Mini Digital Video Camera - about £6 Eachine RC832 Boscam 5.8G 48CH FPV Receiver Combo - 5.8Ghz Tx and Rx - about £14.80 7 inch Professional FPV Aerial Photography Monitor For Ground Station - about £17.50 FPV-Pro-DVR-Mini-Video-Audio-Recorder - about £11.30 Plastic-FPV-PT-Pan-Tilt-Camera-Platform - 99p! I also got an extra stick - about £10, a nice plastic box - about £25(!), and various connectors, switches, etc. The box contains a gel battery for the video, which can power the main R/C transmitter down the connector line - that's what the buttons and voltmeter on the panel are for... Note that the video transmitter runs hot - most of them seem to - which is fine on a drone, but thermal control needs some consideration on a boat. You can see a little heat-sink that I added.... P.S. Oh, and you'll need to arrange a 180 deg servo for the panning... P.P.S. You might want to consider a clover-leaf aerial. That enables what they call 'circular polarity' transmission, which is really useful for drones when the transmitting aerial is performing contortions in the air. For boats, a vertical aerial pumping out vertically-polarised waves may suffer from 'bounce' off the water surface, which turns the reflected waves horizontal. But these are very cheap anyway, and can be experimented with - a bit like different ...

5 years ago by DodgyGeezer