Adam Colins 2 Posted October 10, 2016 Share Posted October 10, 2016 HelloCan you help I have a small F3A aerobatic model wingspan 1220mm weight 970g fitted with a turnigy D3536/8 1000kv motor turnigy 30 amp esc and a 3s 2200 lipo. Swinging a 10x6 prop.My problem is that it seems underpowered. Is there anything I can do or is it a case of replace motor and esc. My understanding is that for a aerobatic/sport model it should be about 150w per lb. The motor is 430 wattEdited By Adam Colins 2 on 10/10/2016 21:45:02 Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted October 10, 2016 Share Posted October 10, 2016 Hi Adam....do you have a Wattmeter? What current & watts is the motor consuming currently? I would have thought you would be in the ballpark with that motor & that prop...a bigger prop will develop more power but we need to be sure you don't overload either the motor or the ESC......things tend to melt. A wattmeter is the answer...we need some figures to know more about what is happening.... Quote Link to comment Share on other sites More sharing options...
gangster Posted October 10, 2016 Share Posted October 10, 2016 I would have thought you would have had enough power with that set up for a 970 gram model. Although as you say it's a 430 watt motor you would exceed the 30 amp limit of the motor and esc if you tried to prop it to that power. Perhaps the simplest method would to be to up it to a 4s set up that should enable you to get the 430 watts but keep the current within limits A watt meter is an essential tool for playing with power train set ups other wise it will end in tears. Such a meter can be bought very cheaply Quote Link to comment Share on other sites More sharing options...
Adam Colins 2 Posted October 11, 2016 Author Share Posted October 11, 2016 Thanks guys, I will purchase a watt meter and get back to you with figures. Quote Link to comment Share on other sites More sharing options...
Adam Colins 2 Posted October 12, 2016 Author Share Posted October 12, 2016 Well it seems the motor is only putting out 175.6w and 15.5a at full throttle. My guess is a bigger motor and esc.. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted October 12, 2016 Share Posted October 12, 2016 I disagree Adam......all you need to do is make the existing set up work a bit harder......your existing ESC will happily take 30A (actually I'd limit it to 25A as anything working flat out will have a shorter life) all you need is a bigger prop.....try an 11x7 or a 12x6 & see where that puts you.... As well as a wattmeter you need a big bag of props to be successful in electric flight.... Let us know how you get on... Quote Link to comment Share on other sites More sharing options...
Geoff S Posted October 12, 2016 Share Posted October 12, 2016 With modern brushless motors 100 watts/lb is more than adequate unless you need blistering performance. Change the prop until that's what you're getting ie about 200 watts and around 20 amps but 25 would be stacks. After all your model is only about 2lbs in old money Geoff Quote Link to comment Share on other sites More sharing options...
John Muir Posted October 12, 2016 Share Posted October 12, 2016 Adam, just try a bigger prop first. Maybe a 10x8 or 11x7? Check the amps each time and keep going up a size until you get to near the maximum quoted for the motor or esc, whichever is lower. I have a 35-48 1000kv running a 12x6 at about 36A, 380W so a bit smaller than that should be about right. A selection of props will cost a lot less than new motor/esc and be a lot less hassle to change. Quote Link to comment Share on other sites More sharing options...
Adam Colins 2 Posted October 13, 2016 Author Share Posted October 13, 2016 Thank you everyone I am going to try different props and see if I increase the watts. I will keep you all posted Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted October 13, 2016 Share Posted October 13, 2016 Bigger props -- larger diameter and/or more pitch -- will increase the watts. That's why the wattmeter is so essential. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted October 13, 2016 Share Posted October 13, 2016 Just run a 10x6 APCe prop and that 1,000 kv motor through e-calc and it gives rpm - 8,800 thrust - 1267g Amps - 21.6 amps at 10.4 volts (approx 225 watts) So it seems your setup is not performing as it should, this could be either the ESC LVC is set too high and is keeping the amps down, it's not going to full throttle, or you Lipo is not maintaining volts under load. But based on your watts at 15.5amps it's holding 11.3volts, so not too bad and unlikely to be the LVC at that voltage. Can you confirm what prop you are using, those results are more like a 10 x 4.5. Quote Link to comment Share on other sites More sharing options...
Adam Colins 2 Posted October 14, 2016 Author Share Posted October 14, 2016 WOW Thanks for the help everyone. I hooked my set up to the watt meter with a 12 x 8 apc prop and it is pushing 340w at 35a....I think i will increase the esc size to a 40 or 60amp though So i think i will look at about a 11x8 or 11x10 prop and i think i will be somewhere where i need to be, Thanks again for all the help and info this has greatly helped me with future setups.. Like the saying goes if you don't ask you don't know... Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted October 14, 2016 Share Posted October 14, 2016 Good news Adam....incidentally what is the C rating of your battery? This dictates the maximum current you can draw from the battery....for instance if you drew 22A that would be 10C....(10 x 2.2A equals 22A) & this would give you 6 mins at full power for a completely flat battery....draw 44A & you would get 3 mins....you see how it works? Also draw too much current & you will wreck the battery Quote Link to comment Share on other sites More sharing options...
Adam Colins 2 Posted October 16, 2016 Author Share Posted October 16, 2016 Hi Steve The battery I am using is a 25c overlander 2200mah 11.1 3S... Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 16, 2016 Share Posted October 16, 2016 Adam Just remember you don't get something for nothing. Drawing 35A compared to 15.5A will shorten your available battery duration considerably. I doubt you will be using 35A all the time but even so things will get hotter and be a bit less efficient so to be safe whatever duration you were working with on your 'under powered' set up - halve it! And if you fly 'tearing up the sky' limit it to 1/3 - at least to start with. Edited By Simon Chaddock on 16/10/2016 16:35:14 Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted October 16, 2016 Share Posted October 16, 2016 OK so a 25C battery will allow 25 x 2.2A = 55A max current so you have a bit of headroom there.....I prefer to keep my batteries to around 10-12C max. This gives me good duration & (I hope) allows the batteries to last a few more cycles... Quote Link to comment Share on other sites More sharing options...
Adam Colins 2 Posted October 19, 2016 Author Share Posted October 19, 2016 Hi all,Well good news...put a new apc 11x8 prop on connected to watt meter and now 260watt at 26amp...Think this is about where I need to be. Thanks again for the help everyone Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted October 19, 2016 Share Posted October 19, 2016 Sounds perfect Adam......everything is working well within it's limits. Bee interesting to see how the model flys now... Quote Link to comment Share on other sites More sharing options...
Adam Colins 2 Posted October 19, 2016 Author Share Posted October 19, 2016 I will update you on fingers crossed improved flight..thanks again for your help Steve. Quote Link to comment Share on other sites More sharing options...
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