Guy Pickett-Jones Posted June 18, 2016 Share Posted June 18, 2016 Afternoon All, Any suggestions / advice for a 'direct swap' for a brushed 540 Motor for something Brushless? Bit of background - The Motor is for a Precedent Electra Fly Glider. The main issue is that the motor fits into a pre cut 'hole' the same diameter of the 540 motor so size is crucial as I don't really want to start making changes to the motor area. Ideally it would be good if it could be a Inrunner - not asking for much I know. Main reason for the change is the standard 540 Motor just doesn't have the power to get any sort of decent climb rate. I have tried a Tamiya tuned motor which just overheated - probably due to being fully enclosed? Current battery setup is a 2S Lipo. Thanks for any advice, Guy Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted June 18, 2016 Share Posted June 18, 2016 Why don't you give 4-Max a call, here. They should be able to recommend a suitable in-runner BL motor of the correct dia, and Kv to suit your model. Quote Link to comment Share on other sites More sharing options...
Guy Pickett-Jones Posted June 18, 2016 Author Share Posted June 18, 2016 Thanks Piers, Yes I have used 4-Max before and have seen their 540 size Inrunner. Initially was a bit more expensive than I'd planned for and was recommend for 3S or 4S Lipos - ideally want to keep my set-up at 2S as these are the packs I have for the glider - it might be what I have to go with though in the end! It's one of these back-burner project if you know what I mean so want to keep it simple and cheap!! Too many other projects on the go as it is!!! Guy Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted June 18, 2016 Share Posted June 18, 2016 I know what you mean Guy. A while ago I bought an MPX Merlin to chuck in the back of the car for impromtu flying sessions whilst on my travels. I thought the MPX power set a bit pricey so I bought a cheap alternative.... I ended up buying three motors before I found the perfect power train, kind of defeated the object really. if only I had bought the MPX one in the first place! Quote Link to comment Share on other sites More sharing options...
PatMc Posted June 18, 2016 Share Posted June 18, 2016 If you have room for about 2 or 3 mm more than the brushed 540 either of HKs smaller outrunners in a can should be suitable. This 1400kv version is in stock in UK & EU warehouse but this 960kv version is out of stock in UK however price is nearly identical & postage might even be less from EU. The 1400kv version should give plenty from 2s on a 10" to 12" dia prop. The 960kv version would need a bigger dia prop on 2s & be more suited to 3s. Trouble with limiting to 2s is that you'd be drawing more current so need a heavier rated esc for the same power than if you went to 3s. A suitable 3s battery costs around £10 each depending on capacity you want. My own choice would be the 960kv motor, a Zippy or Turnigy 3s 25c - 35c 1500 - 2200mAH & a 40A - 50A esc driving a 12" dia Graupner or Aeronaut folder. Cost without prop but with 2 batteries about £60 + postage. Quote Link to comment Share on other sites More sharing options...
Guy Pickett-Jones Posted June 20, 2016 Author Share Posted June 20, 2016 Hi Piers There’s a saying in there somewhere – you get what you pay for I have so far gone through two additional motors date. The original 540 motor that came with the glider had one of the brush mounts break, so a replacement was purchased. I then tried the 540 Tuned motor but this, for some reason the overheated and burnt out… Again in hindsight the combined cost to date and I’d been close to the 4-Max motor!! Oh well! Hi Pat, I have seen the motors you mention but size is an issue. As the below photos show the front of the glider is bored out to take a 540 motor exactly at a diameter of 36mm. Again this goes back to the need for a direct replacement. The motor is fully enclosed, which could be an overheating issue with the tuned motor?? but the set up and build is exactly as the original plans stated – not that I personally built this model as I picked it up second hand. Again the original power came from a 7.2V Nicad pack with the 540 motor on a simple switch, hence going with the 2S Lipo set-up. The idea of using the Lipos was to help reduce weight. The original props are still being used, although I have tried others but the climb out on the 540 motor just seems very sluggish and in a bit of a breeze you’re almost stationary! Again as mentioned I don’t really want to make major changes to the front as it suddenly becomes a much bigger job. The glider flies nicely as is, once at height and is good for a gentle fly about. Guy Edited By Guy Pickett-Jones on 20/06/2016 21:41:20 Quote Link to comment Share on other sites More sharing options...
PatMc Posted June 20, 2016 Share Posted June 20, 2016 I think you should be able to enlarge the clearance to take a Gliderdrive motor or 35mm outrunner without much difficulty using a Dremel fitted with a drum sander tool. With the power available from one of these motors you'd only need run the motor for 30secs or less per launch to get to a thermal hunting altitude so overheating need not be an issue especially if you went for a 3s lipo. IMO the 4Max motor would have been a waste of money, you certainly get what you pay for but you'd have paid for an overpriced, heavy lump of out dated disappointment. Quote Link to comment Share on other sites More sharing options...
Guy Pickett-Jones Posted June 21, 2016 Author Share Posted June 21, 2016 I think I might have to accept that I am gong to have to do some mods to the front! One other question which was knocking about whilst looking for motors was: If a motors spec stated suitable for say 3s to 4s lipos, would there be any harm in running it on 2s? I can fully understand that running over the recommend lipos will cause problems but under powering - obviously your not going to get the same rpm etc based on the KV values, but would you be doing any harm? Quote Link to comment Share on other sites More sharing options...
PatMc Posted June 21, 2016 Share Posted June 21, 2016 It doesn't matter what voltage is connected to any motor, so long as you stay within it's current limit by adjusting the applied load [prop size] accordingly. However there will be a practical minimum size prop that’s useable for a given model & this will govern the number of cells in series that’s suitable for the model/motor combination. For example a small racing type model might be fine with a 4” prop on 6s lipos with a particular motor but the same motor used in a motor glider would require perhaps at least an 8” prop so 3s lipo might be the practical limit. But of course if a lower kv version of the same motor was used in the glider the prop dia could be increased and/or the lipo count increased. Note this also means that the potential power of any given is directly proportional to the number of cells used. Quote Link to comment Share on other sites More sharing options...
John Emms 1 Posted January 22, 2017 Share Posted January 22, 2017 I realise that this is over 6 months old, and I also realise the desire to keep costs down. We have a couple of factory recon 500 size Mega 22/30/3 and 3E, designed for use on 6 to 7 cells in 2M gliders, so there is no change in CG, and no mods are needed to the model. 6 to 7 cells IS 2S LiPo. Edited By John Emms - Puffin Models on 22/01/2017 19:51:37 Quote Link to comment Share on other sites More sharing options...
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