Help with setup

[Adam Colins 2]

Hello

Can 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 watt

Edited By Adam Colins 2 on 10/10/2016 21:45:02

[Steve Hargreaves - Moderator]

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....

[gangster]

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

[Adam Colins 2]

Thanks guys, I will purchase a watt meter and get back to you with figures.

[Adam Colins 2]

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..

[Steve Hargreaves - Moderator]

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...

[Geoff S]

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

[John Muir]

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.

[Adam Colins 2]

Thank you everyone I am going to try different props and see if I increase the watts.

I will keep you all posted

[Allan Bennett]

Bigger props -- larger diameter and/or more pitch -- will increase the watts. That's why the wattmeter is so essential.

[Frank Skilbeck]

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.

[Adam Colins 2]

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...

[Steve Hargreaves - Moderator]

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

[Adam Colins 2]

Hi Steve

The battery I am using is a 25c overlander 2200mah 11.1 3S...

[Simon Chaddock]

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

[Steve Hargreaves - Moderator]

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...

[Adam Colins 2]

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

[Steve Hargreaves - Moderator]

Sounds perfect Adam......everything is working well within it's limits.

Bee interesting to see how the model flys now...

[Adam Colins 2]

I will update you on fingers crossed improved flight..thanks again for your help Steve.