Electric setup problem

[Simon UK]

Hi Guys 

 

This is my first post, and any help would be greatly appreciated.

 

I am relatively new to the hobby and have just completed my first electric refit. I bought an Artech Wing Dragon (4 channel) a few months ago and quite quickly have become bored with its low power. After a fair amount of research I ordered a Brushless outrunner, an ESC, and a Lipo. 

 

Today I just finished soldering all the required connections; I used Deans (clones) on the battery and ESC ends and 3.5mm Bullet connectors for the motor to ESC.

 

I installed the motor on a hardwood mount that I made and connected everything up. Firstly I ran the set-up with the 8 cell Ni-MH 1000mah that came with the Wing Dragon. Everything seemed to perform flawlessly. Then I tried connecting the Lipo, this is where the problems kicked in. up to about 50% Throttle the motor behaves normally, from 50% onwards it gets very erratic. It gains RPM then Loses RPM and this fluctuates on and off. I have no idea what the problem could be so any help would be as I have said above Greatly Appreciated.

 

Motor is a Tower Pro 2408-21T-3A

ESC is a Hobby King Hk-30A ESC

Battery is a Rhino 1350mah 25C 3 cell

 

 

I have noticed that the propeller is quite loose on the shaft, is there any sort of adapter I can get to make it tighten?

 

Many thanks

Simon

 

 

 

 

Edited By Simuk on 11/11/2009 16:02:42

Edited By Simuk on 11/11/2009 16:03:20

[Romeo Whisky]

Hi Simuk and welcome to the forum.

 

Difficult to know exactly what caused this problem, but it is possible the motor or ESC were overworked by the significantly higher voltage of the LiPo compared to the NiMh, which would mean pulling more watts unless you propped down (smaller diameter or finer pitch propeller).

 

If you're just starting but intend to stay with the hobby, you really do need to get yourself a Wattmeter (BRC Hobbies stock these, as will virtually any model shop selling electric flight stuff).  By connecting this between the battery and ESC you will see all the key numbers which tell you whether or not you've got a good setup, or whether you are over-cooking the motor or ESC. 

 

Happy landings.

[Tim Mackey]

Hi Simon, and welcome aboard.

If its not as RW suggests, then It could be that the voltage is sagging under load, and the LVC is activating, ( unlikely mind, as the rhino packs are good ) - also the prop should NOT be loose, what type of prop adaptor are you using ?

That motor is quite a high Kv ( 1400 ) and only rated to 16A for short periods - I reckon you are overpropped as RW says.

Edited By Timbo - Administrator on 11/11/2009 16:20:05

[Robert Bromwich]

Hi simon and welcome

just one thing that it might be is have u set up the full throttle setting on the ESC and also set it up for lipo's etc ??

if not goto hobbykings website it says how to on there for that ESC

 

rob

[Simon UK]

Thanks guys

 

I do have a Watts Up is this of use? , Getting my head around all these numbers is hard im afraid but I am trying. 

 

I did go with the Apc 7x6- E's I did this as some guys on the Hobby King website had said they where getting good results from these. My prop problem is it's a pusher and I can't go any larger than 7" as it will hit the fuzz. 

As the motor only being rated to 16A, I was totally unaware of this Timbo. As I am on a tight budget I went with Hobby King as they are really well priced sadly the instructions and other data goes out the Window.

 

When I did connect the Watts Up to the set-up I noticed the first reading (top left) was going as high as 19A, I take it I am over stressing the motor then Guys?

 

As to fitting the prop Timbo I just used the small adapters (made of the same stuff as the props themselves) a washer and nylon threaded lock nut that came with the motor. The prop doesn’t get really tight with this set-up though.

 

Thanks for your help guys. And RW I am totally hooked on the hobby already and will be staying with it till my grave (hopefully not for a few decades yet - god willing).

 

Edited By Simuk on 11/11/2009 16:33:46

[Tim Mackey]

Yes - the motor will let out the magic smoke if you let it get to 19A.

The prop adaptor you mention is actaully a shaft diameter sizing ring - supplied with most small e props to get a good match for the prop hole to the shaft of any particular motor . However, how you actually fit the prop to the motor is another matter, and again, varies from type to type, but whichever method you use it must be TIGHT

[Tim Mackey]

I think from memory those tower poo ( ) motors use along spindly shaft, with a thread on em. hey are usually used with slow fly GWS ornage style props, ither with a prop saver type O ring fitting, or simply tightened up on the shaft/hub with a nut. If its the latter, then maybe you need to pack out the thickness of the prop hub with a washer or two , so that the nut is actually in contact with, and pressing against the prop hub tightly IYSWIM

How about a picture for us to help with the diagnosis.

[Simon UK]

Thanks for the info Rob i will program the esc now. Timbo would you have any suggestions as to how i get the system to run within the Amps rating of the motor? I really do not want to see the Magic Smoke! I do have the problem of only being able to fit upto 7 inch props though. As to the prop being loose, i will call into the LHS tomorrow and see if i can get a prop adapter for the motor.

[Simon UK]

I will sort out  some pics shortly TImbo

[Simon UK]

a couple of pictures

 

 

Watts Reading on 8.4v nimh not fully charged

 

 

[Tim Mackey]

Well at those sort off currents - its not an over propping problem

When you stick a 3s Lipo onto that, the volts will probably go to around 10.5 and the current will increase, together with the watts. However its still going to be well within the motors limits. I take it you have got the prop on the correct way around, and the motor turning the correct way also?

[Simon UK]

Umm i think the prop is on the correct way round, the plane try's to take off from my hands if that helps.

New reading on 3/4 throtle with lipo connected (good news is after adding a nut as a spacer, i am able to tighten the prop completely. Got to  3/4 throtle with no hicups ok, problem now is am i gonna fry my motor at full throttle?

 

 

Edited By Simuk on 11/11/2009 18:19:48

[Bruce Richards]

I think you need to try some smaller props 7 X 4 or 6 X 5 if you can get them. I am surprised you are drawing so much current on that set up. May be you should try it on a 2S battery.

[Tim Mackey]

Agreed.

[Simon UK]

Ok guys thanks for the help, i will try to aquire a 7x4 and a 6x5 and see what difference they make.

 

Failing that i will go to 2 cells.

[Frank Skilbeck]

mmm 8.4 NimH at full throttle = 40W 3s lipo at 3/4 throttle = 170W, should go OK just make sure the wings stay on

[Ady Hayward]

Hi,

Just looking at your pic.... If the plane is a pusher then you have got the prop on the wrong way round. The one shown is a tractor prop, not  a problem if the motor direction is reversed.

 

Adrian

[Simon UK]

Hi Adrian

 

Thanks for that, switched it around after Timbo mentioned it earlier. Lipo readings where taken with it correct way round.

 

Cheers

Simon

[Simon UK]

Yes Frank 600 grams of plane with 170w of power should go kinda well i hope

[Tim Mackey]

Ridiculously so - far too much power for this type of model IMO.

I would drop to a 2s and enjoy the long duration that will ensue.

[Simon UK]

Argh!

 

ok Timbo you win, i will buy myself a 2 cell battery.

 

I will stick with the 7x6 props that i have (bought 6) and drop to 2 cells.

 

Now to source a 2 cell that will fit in the front of the plane.

 

Thanks for all the help fella's safe flying!

[Hamish]

Simuk

 

Totally off subject but great that you posted pictures.

 

I have just acquired an Banchee and have been trying to get my head round how the prop attaches to the motor.  Had worked out the prop saver route with "O" rings etc which I was not sure about.  Your pic shows exactly how prop attached which was in the back of my mind.

 

New to this electric flight so  any info of great assistance

 

 

Hope you get your problem resolved

[Tim Mackey]

Posted by Simuk on 11/11/2009 22:54:53:

Argh!

 

ok Timbo you win, i will buy myself a 2 cell battery.

 

I will stick with the 7x6 props that i have (bought 6) and drop to 2 cells.

 

Now to source a 2 cell that will fit in the front of the plane.

 

Thanks for all the help fella's safe flying!

 

I have been "playing" with the new 5C chargeable loong max "tipple" packs from Giant Cod.

Impressed so far, worth a look, as they are nice and light too.

This one here is a 2300mahr 2 cell, and as you can see, it fits easily in the nose area of a small (20 oz ) ultrafly hawk.

Chargeable in 20 minutes - assuming you have a charger capable of it .

[Hamish]

I have just ordered Loong Tipple batteries from GC so am delighted with your posting Timbo.

 

Wanted to confirm a email I had sent to GC to amend an order and phoned to leave a message on answering machine. At 10 30pm tonight and got an answer.

 

Whoever I spoke to was in Hong Kong and it was 5 00 am.  Now thats service

[Simon UK]

Ok Timbo bellow is a picture of the current battery i was planning to use.

 

 

 

I can go maybe 1cm more in length and that it (or it will stick out the top of the Fuzz which i don't want.

 

How does the GC battery compare?

 

 

Hamish, i basically just packed out the non-threaded part of the shaft with washers, until i was able to get the prop tight enough that it won't spin on the shaft.