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I do have an inrunner, Doug, for my CNC outboard, but the one we're talking about here is an outrunner as it's the outside that spins and the innards which are bolted to a thick bit of aluminium. You can get the idea from the picture. My dear bride has just bought me an early Christmas present of a new camera which, I hope will take pictures clearly when the sun isn't shining. So my pics should improve soon. Martin
Although have modeling experience, all my earlier vessels used brushed motors. This was my first brushless. The model is now running well, but thought, for the benefit of others considering this transition to summarize my experiences. Must stress the performance of a brushless motor is incredible when compared to a similar sized brushed; for a vessel such as this they are almost obligatory. They are worth the trouble! Had been advised that the best powertrain installation for a 37” Brave Borderer is either a single or twin screws, not three. This was good advice! Much heartache could have been avoided with a single screw installation. Unfortunately, that is not the correct layout for a scale builder. Tried three major powertrain iterations, with several variations within each group. All motors are 28mm O/D : 1) The original installation used 3 x 4600kV inrunner motors with 30 A ESCs. Had bought these items used. The motors were too fast and had little torque. The ESCs also did not have adequate capacity. The result was erratic performance, a high fuse failure rate and the eventual failure of an ESC and motor Picture #1. 2) First upgrade was to 2 x 2400kV inrunner motors, using 50A capacity ESCs. The centre shaft was fitted with a brushed motor. This combination did work, although suffered greatly from motor “squeal” and “stutter”. Eventually a motor burnt out and failed. Picture #2 3) Upgrade two: retained the 50 A ESCs, with 2 x 2600 kV outrunner motors, again with the brushed inner shaft motor. Reprogrammed the ESCs to soft start parameters. Much better, performance and reliability can now be considered acceptable. The squeal and stutter are largely corrected It has justified the challenges of getting here. Picture #3 Have tried both 2 and 3S Li-Po batteries, suggest use the minimum voltage needed to achieve the desired performance. Higher voltages translate into faster response and performance, but with less control modulation. The model can be easily overpowered. In summary, from my experience. For a marine application; chose low (under 2000kV) kV rating motors with an outrunner layout wherever possible (produce more torque than inrunners). Use ESCs with a ratings comfortably in excess of the motor ratings, fit fuses to supplement any ESC protections. Ensure the ESCs are programmed to “soft start” characteristics. Also, the obvious check of making sure shaft alignment is correct is even more important with the higher speed capability of brushless motors. In spite of the trails, cost and tribulations of getting here. Have enjoyed the challenge and the end result does justify the means. Also, do not finally fit the deck until you are satisfied with the performance. Making the changes described with limited access would have been very difficult and frustrating.
Hi chaps jim dogge here, im just about ready to fit out my wave princess with some sort of motor and bits. I have allsorts of outrunners and ESC to match aeroplanes but havent a clue as to where to start. A 1.5 diesel, whats that equivalant too is the weight thrust formula the same for boats. l would prefer to stay with out runners, the cooling aspect is no problem l did it for a living. a prop size how is that worked out for a boat.
Hi all, here's progress on the Darby One Design. Got these pics just before it started peeing down, so no Chris-Craft pics. Fitted a brushless outrunner I found in a box. Might work, might not... Home made prop shaft/tube, home made off-set rudder. Planked balsa top cover to keep weight down. 1/6th scale 26"long, 10" beam. Thick grey cellulose primer to act as a light filler for scratches, etc. Martin
[Score: 9/10] 29"/1200g Avanti Capable of 15mph and a runtime of 5mins Single Propellor (2 Blade X Type 35mm) Direct Drive to a OBL29/19-15M (2 Blade X Type) Powered by LiPoly (11.1v) 15Amp/h Batteries Controlled Through BLC-40M (25Amps) ESC - Comments: ARTR fast electric by Thunder Tiger. Deep vee powered by Ripper Brushless outrunner. Will reach 30mph+ when flat out. I replaced the radio that came with the boat with stick operated Futaba T2HR as I preferred "stick" to wheel for sailing fast boats. Initial problem was slight leak where stern tube passes through the transom but soon fixed it with epoxy. Electrics are in a box at the stern which is appears to be water resistant. Though not for a raw beginner, it is great for a second boat especially if someone is hoping to move on to a 6S . If not , it makes a good all rounder and is ideal for club fast electric racing and it performs well when doing tight turns. Boaty
Been researching the squeal and stutter on other websites and conclude RFI is probably not the major contributor. Others attribute it to a mismatch in the ESC / motor timing, which seems more likely. Whatever caused it, resulted in the affected motor failing. Which came first, the failure causing squeal or squeal causing failure is open to conjecture. Much to my surprise the manufacturer has decided to replace the motor under warranty. In the meantime, the motors I had planned to use originally (2800kV Outrunners) came into stock, so purchased a couple. Until now have had to use the ESC default settings as did not have a programming card. This also arrived with the motors. Following advice from another contributor reprogrammed the motors with “softer” start and acceleration settings. Fitted and tried the new motors and settings. On the bench, the squeal and stutter have almost gone. The motors are also more tractable. As the brushless motors are now going to be used for high speed operation only, with slow on the centre brushed, thought could simplify the controls by putting the brushless ESCs on one control system using a “Y” lead. However, this introduced inconsistent and erratic motor responses. Reverted to the two previous separate controls, port and starboard. On the water the performance is fine, as is the reliability. The 2S battery gave almost half an hours operation. The bow lifts nicely with both 2 & 3 S Batteries; plenty of spray. Hopefully resembling a 50 knot vessel! Another adjustment is needed to the transom flaps to try to hold the bow down later as she accelerates. Feeling now to finally be making progress with this model. The squeal has not gone, nor has erratic motor operation. The squeal is high pitched screech, rather like treading on a budgie! When it happens, bringing the control back to neutral and advancing it again almost always overcomes it. The erratic operation happens also when starting and is rather like the motors are not getting a signal to react to the control. Again, returning through neutral briefly seems to correct it. The revised motors and ESCs have increased the weight to 6lbs for the hull including all running gear, excluding batteries and superstructure. Whilst still trying to control weight have concluded this figure is satisfactory as the performance certainly is.
Hi Ira, Aha! the 1/20 version. So she has some carrying capacity👍 Here's a recommendation from RC Groups- "I have a 1/20th Elco hull based on a John Drain keel and bulkhead kit from Australia. It is powered by three 3548 770KV outrunners turning 1 1/2" three blade props, three separate ESC's, and three 3500mah 4 cell LiPo battery's. Running weight is 16 lbs., capable of speed far in excess of scale, run time is great. " Sounds good to me! For reference; I have a 28" version, being renovated and upgraded. It has 2x 2832 brushless driving 3 blade 35mm props. Guy I bought it from said it was too fast for him! I'm considering adding an independent centre motor, a simple brushed job for slow cruising / manoeuvring. So the above seems reasonable for a 4footer of 16lb. Cheers, Doug 😎
Thanks, Doug, the blue brushless is held by something that grabs the smaller cylinder and the rest spins round, ergo, outrunner. If I ever make a lightweight I might try one in there. The brushed 400 I will try in the Sea Hornet. Gotta be worth a try. And that Simprop should be OK for it, n'est ce pas? What concerns me is the lack of sizes available in props. They all seem to start at 35mm which might be a little too hefty for the 400, but I can't find a 30mm anywhere. I also found the Hornet II I carved a while back with a view to getting it scanned for frame sections, so that's another wee job to finish off. I am looking forward to doing that one. Cheers, Martin
Q: What does one do when one reaches the age when hand/eye coordination falters and advancing macular degeneration results in your flying models, overloaded with tape BandAids and superglue, making unexpected 'arrivals'? A: Retrieve the 'innards' of the 'foamie', add a few sheets of balsa and build a maxi-size Skimmer a la Glynn Guest but x 1.4 to take the brushless outrunner rom the late 'Easy Star'! Help please ..... I only have a MP4 video clip of 170 Mb - how do I load that?
Read further down and he clarifies that. Apart from that you can regard all brushed motors for models as 'In-runners' if you will! BTW: your last video was interesting, as far as it goes, for those into breaking the model boat speed record or competitive racing. For me the the boats themselves are totally boring, but that's just me 😉 I suspect that the majority of us here are more interested in scale modelling with a run time of more than 5 minutes. I believe Martin's planes are relatively small so I'm not sure if a small prop will be be a limiting factor. Choice will likely finally depend on the space available in the fuselage! Like I said 'Each to his own' 👍 Anyway, I'm convinced; leave the In-runners to the car racing boys😉 I only have outrunners anyway, even my Catalina arrived with two outrunners!! Mus check the 'Flying Wing' again😲 Thanks for the heads up! 'Tempus fugit' and progress too! Cheers, Doug 😎