BECS and regulator info ( beginners )

[David Lawrence]

Your sympathy is appreciated, Timbo!

I live out in the sticks, far from model shops (nerest one closed down) or clubs, and have never had any problems with ic, buying most stuff by mail order, but now feel it is the responsible thing to do to switch to leccy and 2.4 (I was a bit worried that I have seen quite a few RTF heli's around in random fields/gardens, which appear to be flying on 35mhz, and I am quite sure that none of the kids flying them has the remotest idea that there is such a thing as interference!).

I shall plough on regardless,

David

[Tim Mackey]

Dave... i now purchase all my stuff from the WWW as I too live an expensive distance from any model shop.

Maany specialist suppliers will offer good and friendly advice and are very happy to talk you through the equipment you will need if you just tell them what it is you are trying to achieve. Scott and co at Brian Collins ( BRC ) are very good, as also is John Emms at Puffin models, Aurrora, Rob at flying wings.co.

This is NOT an exclusive or biased list, and plenty of others exist.

Also, as I say, please post away with any questions...its what we do !

[Erfolg]

Electric flight is not as certain as IC, in my opinion.

You can pretty much stick any 25IC motor on a suitable model and it will fly pretty much the same as all the rest.

With EF even with a data sheet, it does not guantee sucess. I have found that I must use a watt meter to ensure I am pulling the current that the sheet suggests. Propellers do seem to vary more with EF, or may be it is the controllers etc.

Erfolg

[Tim Mackey]

No...that is a fair assesment Erfolg ( and YES propellor selection is VERY important with EF)

[David Lawrence]

Now, a wattmeter....is there no end to the bits I need!

What will that set me back?

[Tim Mackey]

About half the price of the powertrain that will go up in smoke the first time you put the wrong prop on without using a wattmeter first.

PS please keep on topic

 I am happy to discuss the use of a wattmeter etc on another thread, and please feel free to start one

[David Lawrence]

Ok Timbo....but back to soldering first!

[Myron Beaumont]

David   believe me you ain't even started after getting the basics ;The next thing is more batteries to be able to have more than 20 mins flying a day

  I,ve got 3 gallons of fuel = now I wonder how long that will last?

[Mike Stevens]

I have just read Nigel Hawes interesting article in the current volume of RCME and am now  a little more confused. Nigel states that if using 3S LiPo or up to 8 cell Nimh we could be flying a lethal weapon and we should not be using a BEC or have I missed something?

Now amongst my squadron are two aircraft from Multiplex - a Twin Star II - 8 cell and brushed ESC with BEC and a Gemini 3 cell LiPo brushless motor and ESC with BEC both of which use four servos.

Both were purchased with Multiplex's supplied motor package, ESC's and servos and using the manufacturer's suggested battery options. So, am I correct in thinking that a company with the reputation of Multiplex is designing, producing and marketing aircraft that inherently unsafe as would be the inference of the article particularly on page 109, the last two paragraphs.

As I have said above, I am now a little confused and would be grateful if someone could clarify this for me.

 Many thanks

Mike

[Tim Mackey]

Hi Mike...you might want to read this thread over here also - relating directly to Nigel's article.

Nigel is of course perfectly entitled to his opinion, and indeed if his experience leads him to deploy a separate battery for radio power in a great many of his models, then so be it. Not inherently a bad thing. However, my experience indicates that this practice may be a little bit over cautious - not a bad thing as I say - but I fly very many of my electric models using the ESC built in 5v BEC - some of which have 4 servos and have never experienced a problem. Now maybe I am just lucky, but there you go. Many of todays BECs are of better design and performance than those of yesteryear, and in very small lightweight models the extra weight and fuss of separate supplies is a pain - IMO.

[Mike Stevens]

Hi Timbo

Thanks for that - I shall read it and missed it earlier though(not feeling the Maye West today) - I did have a read of your thread on BECS. The part I can't quite comprehend is that surely manufacturer's are not going to put something on the market which is inherently dangerous in its standard format especially bearing in mine the potential for litigation from our US colleagues should an accident occur but note your comments on current electronic design.

Regards

Mike

[Tim Mackey]

MIke as with most things the way a thing is used by the user is beyond the manufacturers control and the warnings about using BECs are clearly stated in the manufacturers blurb and  - many "warnings" and advice are offered in order to ensure a high degree of safety margin. Most ESCs will warn ( check the small print) about the use of the BEC with high cell counts, or more than 2 or 3 servos. Older style linear BECS were being overworked when asked to drop high voltages from 4 cells or more down to the 5V required for the radio - and smaller digital servos are far more power hungry than older standard S148s and so on. Have read of all the posts and opinions expressed in that other thread - then make your choice. BECS used correctly and within their parameters are NOT "inherently dangerous" - but unfortunately people will push them beyond these parameters...sometimes unknowingly.

[Roy Gallagher]

I am puzled here and am hoping one of our electrical gurus can help me, two simple 30amp Hobbyking ESC's two Hi model 2600kv brushless motors all wired correctly running from one 3s 2200mha battery. should run fine? yet when i throttle up one motors starts before the other and stops before the other all ESC's and Motors bought at same time. anyone any ideas because im pulling my hair out.

[Tim Mackey]

Did you "train" both ESCs at the same time to recognize your Tx throttle movement?

[Roy Gallagher]

Now Timbo you have asked some thing there, by train i assume you mean program, no i did not ,i started one motor up on one ESC first with an identical motor i recieved from Flying wings while i waited for my two new motors of the same model, if that is case what do i need to do to train the little blighters.

[Tim Mackey]

Connect both ESCs and motors. Then ( usually ) move the Tx throttle stick to full high, and then turn on the Rx and then the TX. Move the Tx stick to low and wait for the confirmation beeps. That should teach both ESCs the Tx commands. Then try, and let us know.

[Roy Gallagher]

thanks Timbo, will try that tomorrow and let you know the outcome.

[Roy Gallagher]

Yet another satisfied customer thank you Timbo problem solved. however what i had to do was turn on TX with full throttle, then plug my battery in with the ESC'S and motors all connected up and it bleeped 4 times, then i pulled throttle to low and it then gave confirmation bleeps and whalla they where singing sweet music together and in sink. would not have done it without ya mate again thank you, top man. they are fitted in my GWS C47 which is at the moment undergoing a full revamp as stock motors just dont cut it for me, and it just does not behave itself in air the way i would like it to, so i have cut ailerons short be 6 inches and added 5mm reflex to them at ends which can be adjusted, this to try and solve the problem of it nose diving when you shut off throttle and it's habbit of tip stalling at low speed, i will get it to fly nice if it kills me.

[Tim Mackey]

Nice one Roy - another satisfied customer eh!

The nose diving when off throttle sounds like a motor thrust angle issue to me ? 

[Roy Gallagher]

Yes Timbo i thought that so i have added 2mm of down thrust to the motors with washers on mounting screws, i can tinker with that, may need more, up to now the watt meter is showing 280watts @ 23.4 amps using the 11.1v 3s 2200mha with gws 3 bladed 5x5 prop,  AUW 1.3/4lb. Over 3/4 throttle though i am getting a lot of prop baffle may need to put a fibreglass master airscrew props on

[Tim Mackey]

I find the APC "E" are about the best and most efficient mass produced props for leccy stuff.

Your 280 Watts at 23.4A  means your 11.1V nominal lipo is holding 11.96 volts under load !

I always reckon that a 3s under load will only normally show around 10.5V so either your meter is fibbing a little, or those are very excellent Lipos

2200 mA hr @ 23.4A is over 10C, so they are not exactly lightly loaded either

[Roy Gallagher]

Sorry , wrong info there its an 3 bladed 5x3 GWS and it is a brand new lipo on its first charge so would that be the difference, i am using one of those what meters from BRC so would imagine it to be fairly accurate, it is a 25C batt, I'm not sure on this electric stuff yet but am trying to get my head round it, by reading these excellent threads and books but like i always say you learn nowt till you try it out, and have ago yourself. in my oppinion you only then start getting an understanding of how it all works i.e changeing prop size to see how it affects your performance and battery times.

[Tim Mackey]

Unfortunately I think you may find that the meters are NOT actually that accurate  - someone else complained of strange readings on the same thing

However, I wouldnt fret too much......I doubt the battery is really holding up quite that well, but at 25C rating the current draw you are getting is absolutely fine....and its current that kills motors not volts.

[Roy Gallagher]

On those motors Timbo, they are exactly they same as i have on my Buzz Lightning from Flying wings and i run that on same Battery size i get around 7-8 mins flying time, so assumeing that, would you think running two of the same motors i will get around 5 mins flight time. motors are Type: A2208/8
Prop Size 5 x 5 (speed APC)
No. Of cells:2-3 Li-Poly, 6-8 Ni-Mh/Ni-Cd
RPM/V:2600 RMP/V
Max. efficiency:78%
Max. efficiency current:8-15A (>74%)
No load current / 10 V:1.3 A
Current capacity:20A/60 s
Internal Resistance: 62 mΩ
Dimensions:27.5x26 mm
Shaft diameter: 3 mm
Weight:36g /1.27 oz
And using 30amp ESC's, with the 3 blade 5x3 props with as mentioned all up weight. I would be interested to see how you would work it out.

[Tim Mackey]

Sorry Roy not exactly sure what it is your asking me

Re-word it, and I will get back to you when I return from the afternoons session up the orme!