A few pointers please

[Crampster]

Hi Guys.  I’ve just finished putting together my first aircraft.  I’ve been into RC cars for a while and it seemed like a natural progression.  I have started with a Seagull Innovator EP.  I am up and running but she seems to want a lot of additional weight up front to balance the centre of gravity.  In fact the weight required is the same as the 3S Lipo battery that I’m using.  Therefore could I install two batteries in parallel with one another?  If I have to put weight in the nose best it be useful weight ? Whilst writing, I’m using a Futaba 2.4Ghz 6EX and using this excellent forum I’ve read that I’ll need to reverse the throttle channel (CH3) but it also needs for the rudder (CH4)and steerable front wheel to be reversed.  Is this normal or have I done something wrong ? Any help you can give would be much appreciated.Thanks

[David Parry]

Hi Crampster, can't help with the Lipos, but I do know most EP need weight up front because the motor and speed controller don't give you much weight there, I am sure someone will put you right with the Lipos as for reversing the rudder, no you haven’t done anything wrong, you have just but the servo in the wrong way round, it is common in Planes that what the channel revere is for. Good Luck with the maiden I am sure you are aware you need insurance to fly and I hope you have joined your local club who will help you to get airborne.

[Crampster]

Thanks for your quick reply. Burning the midnight oil?

I’ve just sent off my subscription to Join the Weston Model Flying Club (Weston Super Mare).  I’ve spoken to a few people there and they seem like a great bunch who are keen to give me some much needed help).

As an extension to my original question, what sort of connectors do people use to connect the Lipo up to the ESC and the ESC to the motor.  I’m currently using normal ‘household’ block connectors but I can’t help but feel there’s a much better alternative that I’ll need to install before its maiden flight?

(Note to the moderator; should I have started this thread in the ‘Electric section’ ?)Thanks again David.

[Bruce Richards]

I have an EP model that needed more nose weight and I did exactly what yoiu suggest just added a second 3s Lipo in parallel with the first. Gives twice the duration  plenty for 2 good flights. With regard to the reversing as David said its perfectly normal to have to reverse channels to get them working in the right direction.

Good Luck

[Tim Mackey]

Pleaase remeber that before you connect in parallel, they must all be the same battery and in the exact same state of charge, thereafter, charge in parallel also.

[Crampster]

Thanks David and Timbo,

Any advice about what electrical connectors to use to connect the Lipo up to the ESC and the ESC to the motor.  I’m currently using normal ‘household’ block connectors but I can’t help but feel there’s a much better alternative that I’ll need to install before its maiden flight?

Timbo (after spending a lot of time reading different threads on this forum it seems you are the 'electrical guru' ),  on the back of the ESC there is a metal block that I assuse to be a heat sink ?  How important is it that this heat sink (assuming it is) is ventilated?  I've used it as a nice solid surface to apply some double sided velcro to hold the ESC to the airframe.

 Also, you say chage in Parallel, how do you mean ?

 I last built a plane from scratch at the age of 12.  Its funny but in all that time I didnt notice that my fingers must have got much fatter!  Its taken me ages to install the radio gear and dress all the wires so they are all nice and neat.  Can you give me any advise on this subject? Perhaps I'd best take that one up with someone medical.

Thanks again

[Tim Mackey]

Hi Crampster. The best connectors to use are known as gold bullet connectors, and they come in different sizes, the most popular being 2 /  3.5 / and 4mm. I use mainly 4 mm these days, but 2mm are good up to at least 40A+

The ESC ( and some motors ) sometimes have such connectors fitted, and they are often 3.5mm.....hard to tell them from 4 mm visually, but as I say, I just cut off whatever is fitted, and fit my own. 

The cooling of the ESC is important if it is likely to working close to its current limit - I find that if it is only working at say half its rating, then inside the fus, with no ventilation at all is usually fine. You really need to know what current is being drawn by the setup you have - remember prop chioice is very important in electric power-trains. ASfter a fluight, just feel the ESC ( and motor if possible ) and if it is nicely warm and no more, then it is fine.

If you have elected to use two ( identical only please ) batteries in parallel - which I do alot,  then it is best to make up a harness which will connect them together but still allow seperation at a later date, that way they can be used seperately in other models - I use the aforementioned bullet connectors and good quality silcon wire to make the required harness...sort of like a heavy duty Y lead. It is best to keep them in this parallel connection for charging purposes, as then they will more likely stay in balance with one another. Balancing them "properley" with a standalone balancer or combo charger however is really only possible then by charging them independentally.

I too like a neat installation, and deploy various stuff to achieve it, velcro ties,( B+Q) tie wraps, double sided sticky pads, rubber bands, plastic tubes from old snake outers to run wires through etc. 

Dont worry about the thread location, I will move it over now

[Crampster]

Timbo, you really are a wealth of knowledge, I dont suppose you want to built the next one for me do you ?

I have a lot to learn but I'm a big techie and like things complicated.  initially I thought 'lecky' flight was as simple as stuffing some old batteries into a cheap plane then off you go.  How wrong I was!

My next question might sound completly stupid but how do I know that the batteries are about to give out mid flight?

I'm using 2100mAh 25C 3S1P Lipo's (two of them strapped together now) with a GWS3020/8T motor with a  APC C-2 prop (279 x 140) and a JP E-Pro 30A ESC

Thanks again.

[Tim Mackey]

Your speed controller has a device called an LVC - this will either slow /pulse /or stop your motor when the battery reaches what it considers is a safe low voltage. Power to your radio will continue uninterrupted allowing a safe controlled landing ( assuming all the other parameters are good IE Pilot )

I cannot say how long the battery will last in flight as there are too many variables, but if you know the current draw, then a reasonable estimate is possible. Check this thread out here....just been discussing LVC earlier !

PS there are no stupid questions...only answers 

battery cut off in flight

[Andy Gates]

Crampster

Welcome to electric flight.

My first comment is to get rid of those household connectors.

You need to eliminate any chance of the 2 wires from your lipo pack touching each other. If they do touch for any length of time (couple seconds or more) the pack will be damaged and it could catch fire even a short while after connection has been broken.

I have a thread elsewhere which shows the sorts of connections and link cables that Timbo is talking about using 4mm connectors.

I will post a link and I appologise to all if it is wrong to link across different message boards.

http://www.rchobbyhub.com/index.php?name=PNphpBB2&file=viewtopic&t=4134

[Crampster]

Thanks Timbo and Andy, looks like I'll have to dust off my old soldering iron.  Andy the link demonstrated the point.  Thanks

Thanks to everyone's help, I now know what I need to do to get my trainer running correctly and safely. I've spent hours on the flight sim, seems like all that's left is to do is to find someone to help me get the thing into the air.

Thanks again everyone, very much appreciated.

[Former Member]

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[Crampster]

Eric I heaved it out the window and look where it got me.

http://uk.youtube.com/watch?v=tgWIdpegfuc

Thanks agian eveyone.

[Former Member]

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[Tim Mackey]

No carb even !

[Crampster]

Yeh, thats just my holiday home, wait till you see my Somerset mansion ! (In my dreams)

Timbo, how can I measure the current draw?  I suspect I need to spend some more cash on another bit of kit?  At my level (LOW), would it be worth the investment ?

Thanks again

[Former Member]

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[Tim Mackey]

Or a decent "clamp on " style ammeter - prefer the wattmeter m'self as Eric has suggested.

[Andy Gates]

Have a look around and compare the prices to the price of a Lipo pack or speed control.

Once you realise that the price of a watt meter is around the price of replacing one of the items I mentioned, then it makes an awful lot of finantial and safety sence.

 I use an Irvine model which gives single switchable read out of voltage or current, multiply the 2 together will give you the wattage. Realistically the most important value you will get is the current being drawn. This will show the change in current between things like prop changes, motor changes or pack size changes.

[Crampster]

Guy's, the talk of 'Clamp on's' and 'Speedo's' has left me blushing.   I think for the moment I'll just try and get the thing (aircraft, Eric) into the air and down again without bending anything.

FYI. I've mastered a Harrier on my RealFlight flight sim, shame because I don't think my Seagull Innovator will perform such a maneuver !

Thanks both of you. 

[Former Member]

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