Hi Doug, I have used the floating periscope on my other submarine too. On that one there are two sets of two. If the periscope tubes slide easily and the float is big enough then it will work. I have used aluminium tubes on the HMS Triumph. The U boat scopes are both aluminium. They are loose so I can put one or both in before sailing. The floats are balsa wood and painted for sealing.
My suggestion would be to contact the Kehrer shop directly. They are most likely to answer any of your queries. Looking at the booster nozzle it looks like a circular section squeezed into a smaller square with the cross fins to straighten out the jet thrust.
My crew were made by Shapeways. Somewhat expensive, but I needed an unusual scale. I asked a question and the designer got back to me. I was able to select from a few different groups and he also did a few pose mods. The crew is available as U-181. I think they can be scaled down to any scale, although the Revell U-boat crew are also available and a lot cheaper. Some of them now sail on my 1/72 Z39 destroyer. So far I have put 6 crew members onto the boat and I have 6 remaining. They are mainly for the front 105mm and rear 37mm guns, and more sitting (for the seats on the wintergarden). My periscope has a very simple working method. A balsawood cylinder at the bottom of the periscope. Sub dives and the periscope comes up. Sub surfaces and the periscope goes down.
There are 2 ballast tanks 750ml each - allowing nearly 1.5kg of ballast. I have only fixed half the crew to the boat, and only some key ones in the conning tower. You cannot see them when at a distance and certainly not underwater, so a calculated view. They do stand out on the photos so it looks more realistic. I think the newer tube internals allow for smaller subs but there is hardly any space left within this model.
[Score: 9/10] 77"/17500g U-181 Capable of 4mph and a runtime of 90mins Twin Propellors (3 Blade 35mm) Geared to a Mabuchi 550 (3 Blade) Powered by NiMH (6v) 10Amp/h Batteries Controlled Through MTroniks 20A ESC - Comments: This is an Engel kit, but heavily modified. The deck was replaced with 2mm polycarbonate and slots cut with a slotting tool on a lathe/drill. There are 3 access hatches instead of the original 1. The internal layout was completely revised. The dive system is the Engel Tmax that works very well. There are too many other changes to mention, but suffice to say they were to make the submarine more realistic and also easier to maintain.
Hi Boatshed, Fortunately my submarines and I are safely on the other side of the planet. I agree with Doug. Communication and common sense are essential to happy sailing. 😎 However, a colleague of mine that sails his subs in close proximity to others including out of control yachts, feels the need for a sign. It severely detracts from the realism of the model and has still been run into. Perhaps a 'muppet' flag on 'power boats' will make them obvious and enable local submariners to dive to safety.
An anecdote. My HMS Triumph submarine has a piano wire antenna with the periscopes (not the working antenna) bent to a diamond shaped tip (for safety). A few years ago in the same venue as my previous post above, HMS Triumph was submerged and heading roughly towards the jetty. Hard to know exactly where. I decided to surface to be safe. At the same time three large swans were gliding along gracefully in the vicinity. Suddenly one of the large swans went vertically upwards about two or three feet with his large wingspan fully well extended. The sub's antenna has come up right under his bottom and given him the surprise of his life. The sub surfaced after a few more seconds directly under where he was. It may have got kicked down in the scramble. No damage to either but for the few of us watching it was hilarious. No video unfortunately or it may have gone viral.
There is an old British war movie 'Appointment with Venus', about the rescue of a prize cow. It features a Fairmile D in some great scenes. If one is building a Fairmile D then the boats in this movie will provide inspiration.
Hi Rowen, I have had water cooling on all my patrol boats running at 12Volts, whether brushed or now brushless. For the brushed motors I have used aluminium tube coils with water pickups between the propellers and rudders. I did try water jackets a couple of times but found too much friction loss and therefore lack of flow. For the newer brushless outrunners I use a brass tube soldered to a brass plate across the front of the motor fitted between it and motor mounting bracket. I agree with Doug with regards to the disconnection of the red wires on the ESC's. This is now common practice, especially if you have an external receiver battery.
This Higgins PT boat was built and sailed by a good friend of mine. It is scratch-built. It uses a single Turnigy 3639 1100kV brushless motor and LiPo battery. It is pretty new and has not had its number painted on as yet. Its performance is excellent.
[Score: 9/10] 58"/9000g MTB741 Fairmile D Capable of 9mph and a runtime of 65mins Twin Propellors (2 Blade S Type 40mm) Direct Drive to a Graupner 700BB 12V (2 Blade S Type) Powered by NiMH (12v) 9Amp/h Batteries Controlled Through MTroniks 30A Tio x 2 (10Amps) ESC - Comments: 1/24 Scale. Scratchbuilt from John Lambert Drgs & photos. It took 3.5 years. Plywood bulkheads, pine stringers & balsawood planking, then fibreglassed. Superstructure balsawood. Guns scratchbuilt from tinplate and brass. There are 2 motors and drive trains powered by 2 x 9cell NiMH D cells x 9Ah. 6 pdr guns rotate. 20mm oerlikon rotates and elevates. Radio is Futaba 2.4 GHz
Mr. Grumpy - The reason for a hovercraft skirt is to provide a flexible seal between the craft and the ground/water surface. If everything was flat and smooth, then a shirtless hovercraft would probably work, as a uniform cushion of air could be maintained. Unfortunately this is not reality. I used to like the concept of a hovercraft and once keen to model one, but having seen real ones and models lack of directional control have gone away from the idea. Another reason for the skirt - bouncing off nearby objects in the vicinity of the hovercraft.
I have scratch-built a Fairmile D in 1/24 scale. if you look through my posts/videos you will see it. I used the Lambert-Ross Allied Coastal Forces book for the plan that I scaled up. Perhaps I should enter it in my boat harbour. Anatomy of a Ship is also a good source of information. I built mine from Balsawood/Pine and fibreglassed it. Attached are a few photos. Watch the videos. They may inspire you. I have previously posted these links under videos. https://www.youtube.com/watch?v=a3KotucrlzE&t=20shttps://www.youtube.com/watch?v=Ny718cnD6sQ&t=166s
Hi Graham, There have probably not been any answers so far because we are most possibly speechless. If you go back and read through the comments above you will see that most of the problem has been the large overpowering of your boat (1690 Watts - according to info provided by DaveM), coupled with an inadequate drive train. So with all this knowledge available you have asked our opinion of the Graupner 500ECO - one of the largest motors in that range. This is quoted at 1440 Watts. This may not rip the drive train out as quickly as the other motor did but has enough torque to do so. In my opinion I think you could try a motor producing under 500 Watts and see how that goes - with a 5mm shaft.
Thanks Dave, Eventually we will have put together a body of knowledge that model boat builders can use with some certainty. At present the information is sketchy, hard to find and sometimes ambiguous. The motor designers and manufacturers have not been very helpful. For my La Combattante iii missile boat I used two Hobbyking Keda 720kV motors rated at 215 Watts and 19.3amps max. They were the first brushless motors I tried. I was not sure how many amps they would draw, so I connected an ammeter and fitted my video camera so it read the amps whilst operating. At full speed they used only 8 amps each. Each of the batteries is from 12V made from 9 x NiMH 9Ah D Cells. I easily get over an hour run time at good speed. The boat is 1605mm long so not small. This information may help someone.
Graham, I have attached the same table that Doug sent me. This has the relevant information you seek. According to the table attached the Graupner 500 kV ECO has a specified output of 1440 watts and 80Amps. Strangely the 400 kV ECO has a specified output of 2010 Watts. So the 1440Watt output is questionable and may be a typo based on the other entries in the table. more likely to be 2440Watts In any case you need a 5mm diameter propeller shaft. For shaft alignment i use a brass tube that slides snugly on the propeller shaft and then on the motor shaft. When the tube rotates/slides well on both then the shafts are aligned. I then fit the motor mounts, check and tweak the alignment if necessary, remove the tube and replace with a universal coupling. If the motor or propeller shafts are a different diameter then I insert the relevant size smaller tube inside the larger of the tubes. This method is simple and has served me well, including for larger IC engine powered boats belonging to friends. Haig
Thanks Dave, In common car language that is a V12 in a Ford Fiesta, with the Fiesta drive train. In some ways I believe the brushless motor manufacturers/sellers are responsible for the confusion. Mostly we see the kV, physical size and the number of Lipo cells required. You need to dig deeper to find out the Watts. The kV basically gives the RPM only. No mention of amps and power. We don't buy cars and motorcycles based on the engine RPM do we? Typically if you look at the reputed Graupner Speed Brushless range, they have low kV specs, but the differences between a 400kV 7.4V, 400kV BB 11.1V and a 400kV ECO 14.8V are 130W, 1100W and 2010W respectively. A huge difference. When viewing the on-line retail sites, including Graupner, they all look the same (maybe the same photo), but they are all very different motors. Without the rated amps and Watts (not published) the buyer is left unclear as to what they should buy. Brushed motors are more clearly defined. I must thank Doug for helping me out with Graupner brushless specs when I required assistance.
I get my Raboesch propellers from Cornwall model boats - and I am in Australia. It would be very interesting if there was a video made at the start of this post. How many Watts of power is that motor producing. That is the question I would have asked at the time.