Fair enough pmdevlin I accept what you are saying, however it started as a motor not being big enough for the size of the propeller and then went on further as the shaft was 4BA not 4mm and I could not locate a smaller prop, a plain brass tube and stainless shaft has been fitted,way back in the 60's when it was first started and as I knew nothing about boats in 2015 when I finished the basic structure, I did not know that it would have been the smart thing to fit a shaft with bearings. So this is the way I am going to go, I have ordered the 850 brush motor and the adapter to fit the motor shaft to my red coupling,this I have been assured will be more than big enough to drive the prop without getting hot or needing a water jacket, if this is the case when I fit it and sail it, then result, if not I will then have to go down the path that you suggest, I have nothing to lose trying the larger motor and everything to gain if it works. By the way the batteries are all new
I looked at the Cornwall model site and saw that, what i have decided to do is to leave the two Ni cad batteries in situ and I have weighed the rear/mid section lead weight and it is just 56 grams heavier than the 12 volt 7 amp/h lead acid alarm battery so I will use the 12 volt battery and ditch the lead, the weight of the boat will be the same, I also trimmed the lead at the front end so the bow will come up a fraction more. I have taken the prop of and measured it to be a 55mm, so I am going to fit the water intake, hopefully with some advice from the forum "techys"as to the position, in the photos this is where I can fit it so it is out of the way of the rudder and prop.what do you reckon, I can then get a suitable motor with a water jacket which will be happy to run on 12 volt with enough power not to get hot turning a 45 to 50 mm two blade "x" prop, as suggested by pmdevlin, I may get the Lloydsman up and running as all that needs is dusting of and batteries charging up, (two 12 volt 7amp/h in parallel) and the receiver from the commander fitted although I have not floated it I bought it as a complete working model in 2015, so it is about time it came out of dry dock, also I can look to repairing the rigging and finishing the Odessy Yacht I bought at the same time as the Llyodsman also in dry dock.
Thank you gents, I will get a bigger motor and reduce the prop size as I do not want it any faster than it is, also a smaller prop as everyone has said will reduce the power drained from the battery, I have a water scoop and tubing so will be fitting that today and will fit a water jacket around the motor, also I am thinking weighing the lead weight fitted in the compartment behind the motor and replace some or all of it and fit a 12 volt 7 amph sealed lead acid battery, presumably this will last longer than the present batteries fitted, or will it?
Allen and Doug I see that you both do not sail with or belong to a model boat sailing club so are sailing mainly on your own. Most model boat clubs will have completed a risk assessment and produced guidance and club rules to protect both the members and public. If the waters are Council owned this can be quite a task and can result in permission being removed if not followed. Waters are not easily found and can be lost because of the actions of one individual. Whilst I can sympathise with the desire to recover a sinking/stopped or sunken model there are ways to do this safely. We have an RC rescue boat but I have also used long poles and fishing rods with lines. We also have waders to allow recovery from near the bank under trees etc as well as a boat and life jackets, if necessary, but not I suggest without having help on shore in case of difficulties. You are of course entitled to risk your own life but this is a hobby for me and I suspect many of our members and I prefer to avoid unnecessary life threatening risks. Dave
Hi. The HK controller is an Aquastar 120Amp water cooled which has suffered all of the burn outs and never failed. SKU: 9052000008. The failed motors were all 2848SL 3900kv Brushless Inrunner (WaterCooled) SKU:3900-2848SL. I have my doubts about the specifications as their watts and amps do not add up. I have a temperature sensor on the motor sending info back to the TX and usually after a full charge and a fast run it would get to 60°C, then I would cool it to 45°C before the next run it burnt out at 85°C when I wasn't paying attention. The new motor runs at about 45°C how ever hard it is pushed. Still using the 120A ESC. The new motor was in the HK sale and I don't think they do it now SKU:S2858-2630. It just happend that the water jacket for the failed unit fits it.
Here's another I prepared earlier, I found the file for it on Thingiverse, unfortunately the file made a boat 300mm long, so I printed all the parts at 200% size👍 I've got all the running gear for it now except for the water jacket for the brushless motor, come on China, get your finger out! Cheers Wayne
Hi Allan If you had water cooling and it was provided by your pump then it would seem the prop was far to coarse a pitch for you fast motor and very powerful battery which was quite capable of delivering well over 200 amps through the 160 amp ESC. Your comment re the power delivered rather confirms this, and holding a model at full speed to test is only possible for about 5-10 secs max. You need to get a much smaller and less coarse pitch 3 blade prop plus a wattmeter to measure the current to make sure you are no where near the max ESC current. Personal experience suggests this should be less than half the rated Max so say 70 amps for your ESC. Testing should be brief and stopped immediately if the current being taken is above 20-30 amps. Smaller props will reduce the current to an acceptable level and your model will go faster and for longer. As a guide 14 volts at 70 amps will be using 980 watts so you will perhaps appreciate why cooling is necessary. Also at such high currents the wiring from battery to ESC then motor will need to be capable of carrying such high currents. As there are three wires to the motor and the power is pulsed at high frequency they are usually not as heavy as the battery to ESC. Your battery to ESC connectors also need to be capable of high current such as Deans, Euro or bullet type. Having looked on U-tube it does appear that others have had similar experiences with this ESC. The specs say it is capable of running at 14.4 volts so when you buy a replacement I would ask your local store to run your motor with the ESC and your battery to ensure it works OK. If they have a wattmeter ask them to test the open current then also buy the wattmeter and a smaller 3 blade prop of slightly less diameter than that of the motor without the water jacket. Do a final brief test at home holding the model and see briefly what the wattmeter reads, this will be near the max current draw. If it's too high you need a smaller prop. There are several Perkassa builds on the site and some use brushless with success. If you search you will find details of their power train which may help you choose the best set up. I do hope you will soon have your model speeding round your lake. Dave
PS Allan, there are several water jackets / spiral tubing available for cooling brushed motors, try Hobby King, or just get some alu and silicon tubing and make your own. Apply some heat conducting paste between the jacket or tubing and the motor casing (as used in the electronics industry for mounting power transistors, processor chips etc) available in tubes also in model shop site for a few dollars. Good luck
Hi Allan Was the boat in the water or on the bench? There are several posts online indicating that you cannot run this ESC without water cooling. You did say you needed a separate water cool motor. Is it possible the motor or ESC water jackets were blocked? Hope you can find a solution Dave
Hi Robert, I saw that post when researching this boat, it helped me decide how to continue building the kit. If I do not want to use a water-jacket style motor, is there a motor you would recommend. I have several battery packs; One pack is a 4200 - 7.2 v NIMH The other are two packs both being 2400 - 7.2 NIMH these are with connectors to allow longer run time. Thanks, Ron P.S. I am relatively a new builder.
Hi Simon. The two holes are just so that I could pour some Z-Poxy in after the skins were on, helps seal every thing. The motor is a brushed motor, and I had the water jacket, so it will be fitted, don't think it will need it though. If I ever change the brushed motor for a brushless set up the water cooling is already there. Alan
Thanks Alan, your boat looks really nice, why the 2 holes in the fore deck? I have only just started the build I will post some pictures later. I see you have a water cooling jacket on your motor , I will be buying a new motor as the only power sources I have are sails , this is my first motor build. Is it worth getting a water cooled motor . Simon.
Here's the history bit so pay attention... Many years ago as a boy in the fifth year of my north London secondary school, circa 1971, our woodwork class was given the option to make something of our own choice. Having mastered the majority of joints, wood turning, finishing techniques and the making of table lamps, stools and bookshelves etc. this seemed a good idea, so myself and a fellow classmate and model making chum asked if we could construct a model boat. The teacher, on hearing that it was to be from a kit and not from scratch was a little surprised but agreed. So my friend and I jointly invested about 20 quid in an Aerokits 34.5 inch RAF Crash Tender from Blunts' model shop in Mill Hill (long since gone like many others) and we set about construction during lesson time and sometimes at break times. I recall we used "Cascamite" to glue it all together on the advice of the woodwork teacher because neither 'Scotch' glue nor PVA was suited to marine construction. Good progress was made over the course of our last year at school but it was never fully completed, only requiring painting, running gear and detailing. My friend decided that he needed to withdraw from the project as he was enrolling in a college away from home to study for a career in the merchant navy and I agreed to buy out his share and continue with the project. And so it was that I carried on with the painting and installing the running gear which consisted of a 1.5 cc marine diesel engine, water pickup, prop shaft and rudder and a MacGregor radio system with a stick for steering and a single button for speed control. The engine and radio came from Michael's Models in Finchley (also long gone) for £20 as my elder brother, who had started a Saturday job there, was able to get a staff discount for me. The diesel engine was noisy and smelly and a pig to start with a leather thong around the flywheel and I decided to abandon this means of propulsion (I foolishly ran it for slightly too long 'dry' and melted the soldering around the brass water jacket!). By now I had graduated from my part time job in Woolies to an engineering apprentice with Post Office Telephones and my new income of 20 quid per week could support my modelling and electronics hobbies after my contribution to the household for my keep. So off to the model shop to buy a Taycol Supermarine electric motor, two 12v volt lead acid batteries and a suitable charger. The diesel came out and was sold on Exchange & Mart and the mount and coupling re-made to accommodate the new Taycol motor. What an improvement that was! I can't remember now what speed controller or servo I used but whatever it was did the job, and it went like the clappers on Friary Park boating lake (also long since gone) even though the radio control system was a bit crude with the non-proportional steering and 'blip' throttle control. The boating took a back seat when I acquired my driving licence and my first car (a rusty old Cortina Mk 1) and I also got involved in sound recording for radio. I decided to sell the boat and bits for £60 through Exchange & Mart and bought an Akai 4000DS tape recorder and a 'Chilton' audio mixer, built a home studio and along with a good mate of mine started making radio commercials for the new commercial radio stations including London's Capital Radio. We even won a 'Campaign' advertising award for one of our efforts! And so after several years as a 'phone engineer I moved into professional recording for A/V and broadcast and then into TV production. Fast forward to today. Semi-retired with grand kids and with more free time on my hands I still had an interest in model making so In Jan 2016 went to the Model Engineer exhibition at nearby 'Ally Pally'. It was there that I saw an RAF crash tender just like the one I built all those years ago and got into conversation with the chap on the stand. This re-ignited my model making interests and I researched the hobby and that model in particular.
Hi Brian I am not sure which model you are referring to but your description of period photos suggests it is from the late 1930's and yes they were not a planing hull. Does your model have one or two props? A few pics of the model would help, you can upload by clicking the yellow box to the left of this input panel. Brushless can be a bit daunting at first experience but they are not difficult to use once you are familiar. You will already have seen they have three input wires and these need to be connected to an individual Brushless ESC for each motor. Doesn't matter which wired connect to which socket on the ESC but if your prop spins the wrong way you can swop any two connections to change the directiopn. The kv rating refers to the unloaded speed of the motor for every volt you apply so for say a 1000kv motor supplied with 11.1volts the motor would spin at 11100 revs. There are two types of brushless motor "in-runners" and "out-runners". This refers to the construction used with in-runners generally being less bulky. The outrunners will produce more tork and can be more suited to slower speeds. If you need to water cool the in-runners have a jacket fitted around the motor body whilst the out-runners use a water cooled mounting attached to the bearing. Both are suitable but I personally prefer Out-runners. For your model I suspect an inrunner may be preferable due to the restricted space available. Unlike brushed motors brushless do not like being overloaded and work best when they can achieve their max efficiency at near max revs. They have a max watt rating which should not be exceeded (Watts = Amps x Volts). The casing may be marked with numbers 42-56 which is the diameter 42mm and length 56mm. In my 48" Sea Queen I use a 42 size 850Kv water cooled motor of 700 watts and it is happy driving a Prop Shop prop of 42mm at 45 amp on full throttle. To measure your wattage you need to acquire a Wattmeter to measure the actual current draw with the model in the water. This will give an indication of the max current at max load as you hold the model stationery. If the watts are greater than the motor's rating you need to reduce the prop size/pitch. I like scale props so use 3 bladed brass and avoid using racing plastic/nylon props as they can overload the motor. The ESC should also be of a sufficient rating to handle the running current, I usually try for at least a 50% margin ie 75amps for a 50amp max current. Finally your setup must be really secure (I know from personal experience) and free running. The revs produced are possibly higher than what you may have experience before and any fault can and will escalate very quickly. At high currents the motor coils will fry in about 2 seconds should anything stall the motor and you can expect to see smoke and a ruined motor. If you post some pics we can give you more detailed help on your particular setup. Dave
Hi I peek the motor and speed Controller can you all tell me if its the right speed controller for the motor r not? heres the Specs:Turnigy AquaStar 4084-620KV Water Cooled Brushless Motor RPM/v: 620kv Winding: 2.5Y Max voltage: 37V (10S) Max Current: 105A Max Watts: 3050W Resistance: 0.03ohm No Load Current: 0.7A Can Diameter: 39mm (actual motor diameter) Can Diameter inc. Water Jacket: 49mm Can Length: 84mm Shaft Size: 5mm Weight: 508g Motor Connector: 4mm bullet plug and heres the Speed Controller im going for Specs: Voltage Input: 2~6 LiPoly cells (6~18 NiMh) Continuous Current: 120A Burst Current: 720A BEC Type: Switching with on/off switch BEC Output: 6V@5A Motor Connectors: 4mm Servo lead: JR style Servo Lead length: 300mm Water Cooling Pipe: 3mm I/D~5.4mm O/D Dimensions: 68.5x39.4x32mm Weight: 160g many thanks cliff