Adrian Day Posted February 28, 2011 Share Posted February 28, 2011 hey people! yet another threat to work out how to do something that im not sure of ... So how do you work out what motor is best when changing from I.C To Electric???? this is the set up that im thinking of using can anyone tell me if this would be right ?? i have a 4.5 - 5LB Model with a 40 I.C But want it Electric (INTENDED SETUP) XYH42-50 800kv 43A Outrunner - with a 60amp ESC - And a S4 LiPo Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 28, 2011 Share Posted February 28, 2011 I have already given my input on this to Adrian via PMs.The gist of it being....40 x 2 = 80 +0 = 800 ( Watts) However, of course - we need more info on the type of aeroplane and intended flying style. Also, if he wants 800 watts from a 4s battery, a 43A motor will fry. ( 800 / 14 = 57Amps ) Quote Link to comment Share on other sites More sharing options...
Adrian Day Posted February 28, 2011 Author Share Posted February 28, 2011 I Agree with you there was going to work on the idea of 500watt motor running on a s3 45amps or s4 at around 35amps its that a better working? or am i just not getting it? 100w to every lb of plane 5lb = 500watts its a sports model weight of 4.5 - 5 lb wing sp of 50" what else would you need to know to get better idea?? just for basic flying nothing o.t.t Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 28, 2011 Share Posted February 28, 2011 Firstly the motor can handle 48A absolute max - irrespective of the voltage.3s @ 45 A would only be 470 Watts, and the revs may be a bit low for a sport planeFor a sport plane you need 100 watt per pound ( you got that bit ) so the 4s is better ( 4s @ 35A is 490 Watts.) Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted February 28, 2011 Share Posted February 28, 2011 650KV motor and 6S A123's Tim. Well what else did you expect me to say? Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 28, 2011 Share Posted February 28, 2011 LOL Quote Link to comment Share on other sites More sharing options...
Adrian Day Posted March 1, 2011 Author Share Posted March 1, 2011 i get what you mean didnt know how to do the workings of kv to watts was going to get a motor from overlander but their site doesnt give anything on the workings just the kv to a new flyer that would mean nothing less he was a mathmatician ... glad that some people are on hand to point things out still not 100% sure how to work out the watts from the kv may i ask why you would suggest the 650KV motor and 6S A123's Chris or is that your setup?? i get the revs part being a little slow this is hard to work out wish some makers could do a simple working eq 40 46 so on so on Quote Link to comment Share on other sites More sharing options...
Bob Moore Posted March 1, 2011 Share Posted March 1, 2011 I sympathise with you. I have thought about converting one of my Wot 4's with a 40 engne. It doesn't look easy, and once you get the solution and spend the money you may be looking at £50 a throw for Lipos? For one shortish flight? Because of this of this I' m now considering going lighter weight (and less cost) with the likes of a Fun Cub, and selling a couple of my IC planes? Quote Link to comment Share on other sites More sharing options...
Tom Wright 2 Posted March 1, 2011 Share Posted March 1, 2011 Hi Adrian KV is simply the motor RPM for every volt applied eg 650kv x 12volts =7800 RPM. To calculate watts multiply the applied voltage by the current in amps . AxV=W eg 30Ax12V=360W. Owning a watt meter can avoid damage to motors,esc, and batteries,and do al the the amps volts watts stuff for you,but it is good to understand the theory,Edited By tom wright 2 on 01/03/2011 01:27:16 Quote Link to comment Share on other sites More sharing options...
Tom Wright 2 Posted March 1, 2011 Share Posted March 1, 2011 Hi Bob. The FUN CUB or similar model might be a good to way to get into EP, but not necessarily the cheapest . Converting existing models can be quite easy when you have done the home work. Modern lipo batteries can give much longer flight times than you think and if used properly should give 50 to 100 flights.You are correct when you say lighter wing loadings can equate to longer flights ,and if you have a decent powered glider ,it is possible to fly for hours on one charge using a low cost lipo . There are loads of people on this forum with Wots just ask and iam sure you will get all the answers you need including.....leave it on IC....... . TW2. Quote Link to comment Share on other sites More sharing options...
Bob Moore Posted March 1, 2011 Share Posted March 1, 2011 Thanks for that Tom. I did do some research on here on the Wot's conversion power train and was quite shocked at the overall cost. (Esp with the battery price included.) But as you say, longer term the batteries don't work out so expensive. With all these things if you are using the same battery type in a number of models I think it's not so bad. I agree about leccy gliders. I have an electric West Wings Orion and thermalling and soaring I've had hours of flight. And it does use just one little £6 1000mA 1s LiPoPlus I use the same Lipos for a lightweight Depron Edge. Nice a cheap and simple. I did post in another thread about the power train for the Fun Cub. The official power train is almost a hundred quid, but it can done for half of that! Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted March 1, 2011 Share Posted March 1, 2011 Posted by Bob Moore on 01/03/2011 01:22:11:I sympathise with you. I have thought about converting one of my Wot 4's with a 40 engne. It doesn't look easy, and once you get the solution and spend the money you may be looking at £50 a throw for Lipos? For one shortish flight? Because of this of this I' m now considering going lighter weight (and less cost) with the likes of a Fun Cub, and selling a couple of my IC planes? You're shopping at the wrong places Bob!Edited By Tim Mackey - Administrator on 01/03/2011 16:16:49 Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted March 1, 2011 Share Posted March 1, 2011 Posted by Adrian Day on 01/03/2011 00:27:50:i get what you mean didnt know how to do the workings of kv to watts was going to get a motor from overlander but their site doesnt give anything on the workings just the kv to a new flyer that would mean nothing less he was a mathmatician ... glad that some people are on hand to point things out still not 100% sure how to work out the watts from the kv may i ask why you would suggest the 650KV motor and 6S A123's Chris or is that your setup?? i get the revs part being a little slow this is hard to work out wish some makers could do a simple working eq 40 46 so on so on Have you read these sections Adrian? There really is oodles of info for beginners to leccy flight on here...you just have to make a little time to find and read em all Quote Link to comment Share on other sites More sharing options...
Adrian Day Posted March 1, 2011 Author Share Posted March 1, 2011 Posted by Bob Moore on 01/03/2011 01:22:11: I sympathise with you. I have thought about converting one of my Wot 4's with a 40 engne. It doesn't look easy, and once you get the solution and spend the money you may be looking at £50 a throw for Lipos? For one shortish flight? Because of this of this I' m now considering going lighter weight (and less cost) with the likes of a Fun Cub, and selling a couple of my IC planes? Hi Bob I agree its kind of hard setting up on a low income but i looked a little into things and have found an offset... ok you can pay £50up for a engine and your done but then you add the price of fuel £20 +ok you may get 20 or more flights but if you pay £20 for a LiPo you could get 80 - 100 flights ok you may have to buy the charger but if you have multiple planes buy one for all will last you years so on that its kind of taken my mind from I.C To Electric also due to some clubs not letting you fly I.C Now hardest part is knowing what to get and where is good prices Quote Link to comment Share on other sites More sharing options...
Adrian Day Posted March 1, 2011 Author Share Posted March 1, 2011 Posted by tom wright 2 on 01/03/2011 01:24:56: Hi Adrian KV is simply the motor RPM for every volt applied eg 650kv x 12volts =7800 RPM. To calculate watts multiply the applied voltage by the current in amps . AxV=W eg 30Ax12V=360W. Owning a watt meter can avoid damage to motors,esc, and batteries,and do al the the amps volts watts stuff for you,but it is good to understand the theory, Edited By tom wright 2 on 01/03/2011 01:27:16 Hi Tom thanks for your post thats helped me sort out some of what im looking for on the watts front but im still a little lost the only part thats lost me is that of how does the workings or the maths of RPM equate to power to weight ie RPM needed to pull 5LB of plane to take off so if you have a say 7800 rpm motor what would that pull in weight .... sorry i like theory before i go out and spend money only to find i have got the wrong thing and its useless Best Regards Adrian Quote Link to comment Share on other sites More sharing options...
Adrian Day Posted March 1, 2011 Author Share Posted March 1, 2011 Posted by Tim Mackey - Administrator on 01/03/2011 10:56:07 Have you read these sections Adrian? There really is oodles of info for beginners to leccy flight on here...you just have to make a little time to find and read em all Thanks for that link Tim Looking at it now very informative does take a little time to read them all but its good for the theory work ... hope that i can work it out thanks again for every ones help so far and hope that it helps others Quote Link to comment Share on other sites More sharing options...
Tom Wright 2 Posted March 1, 2011 Share Posted March 1, 2011 Tim Back to your 10-53 post last line did you mean Bob ? . Yup...now changed Edited By Tim Mackey - Administrator on 01/03/2011 16:17:35 Quote Link to comment Share on other sites More sharing options...
Tom Wright 2 Posted March 1, 2011 Share Posted March 1, 2011 Hi Adrian The motor you will need for the Wot is worked out like this ....AUW of the model multiplied by 100W ,say the model is 6lbs then 6x100 = 600W . the next thing you need to know is the continuous current rating of the motor in amps. So say you use a 4 cell lipo you know that AxV=Watts eg 14v x 45A =630 Watts. This tells you that the motor selected must have a current rating of at least 45A. If you then use a watt meter to to confirm the recommended prop for that motor,gives the correct power , for a 4 cell lipo, remember more cells ,smaller prop, less cells bigger prop.All this is well explained within Tim's link keep reading it and ask more questions until you are confident . TW2. Quote Link to comment Share on other sites More sharing options...
david 7 Posted March 1, 2011 Share Posted March 1, 2011 adrian, iam converting my ic trainer to electric, i have spent hours and hours trying to work out a good set up, i think its a bit of a black hole as what size engine, prop, batterys,model weight, etc ,etc, so i whent to brc hobbies who know alot more about this subject than me, i gave them all the the spec i wanted for my model and they came back with the set that is as close to my spec, and i got a good price with there motor/esc combo, good luck what ever route you take. Dave Quote Link to comment Share on other sites More sharing options...
Tom Wright 2 Posted March 1, 2011 Share Posted March 1, 2011 Hi David BRC are very good at advertising the details you need ,and include a user friendly data sheet with all their motors lipos and esc. EP beginners can learn quite a lot browsing such sites,and BRC prices are very reasonable. TW2. Quote Link to comment Share on other sites More sharing options...
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