Power train for Chapter One

[Liam Ryan]

Hi All,

I'm trying to put together my own power train for the chapter one ( I know you can get the kit from 4max but want to try creating one myself - link here **LINK** )

So based on the beginners forums I've come up with the following -

**LINK**

**LINK**

**LINK**

**LINK**

**LINK**

The 4max setup would top out at 25A at full throttle and should be ~8C according to the build article.The gear I've chosen will be adding an extra 300g or so to the AUW which is hopefully ok

This is my first power train so are there other things I need like nuts, bolts, mounts? If the propeller is correct should it be CW or CCW?

As a bonus question could somebody give me the expected runtime of the battery with the setup? My guesstimate is

21A (if 25A full throttle) = 5C = 12 minutes? I'm really guessing the amperage here though

Edited By Liam Ryan on 24/07/2016 12:48:05

[Phil 9]

looks good but the prop size maybe a little small but I'm no expert

Edited By Phil 9 on 24/07/2016 13:26:41

[David Molineux]

Have you seen the website PropCalc? It is really useful for giving you a good idea of how a given setup will perform. I have used it in the past and the results it gave were pretty much spot on to what the actual items gave me when connected to my watt meter. I've noticed that they have restricted it quite a lot unless you pay (used to be completely free) but it looks like it's only a few pence... and if your setup happens to be one that's included in the demo then even better

David.

[Liam Ryan]

Thanks David, it looks very useful but unfortunately nothing there that matches up very well. I'm happy once the basic setup is good and maybe somebody that's good at this sort of thing can chime in on the prop.

The ESC will also power the RX if I've read up correctly so is there anything else needed to fit the power train besides a wattmeter or should all required accessories come with their respective bits?

Since it's an outrunner does that mean a CW or CCW prop?

Btw not asking you directly David 

Edited By Liam Ryan on 24/07/2016 14:15:27

[Liam Ryan]

Ok so taking into account stock levels etc. I've switched things around slightly and here's what I'm hoping will be my full setup -

http://www.hobbyking.com/hobbyking/store/__97461__Turnigy_P606_LiPoly_LiFe_AC_DC_Charger_UK_Plug_UK_Warehouse_.html

http://www.hobbyking.com/hobbyking/store/__26709__Turnigy_3600mAh_3S_30C_Lipo_Pack_UK_Warehouse_.html

http://www.hobbyking.com/hobbyking/store/__36827__Turnigy_D3548_4_1100KV_Brushless_Outrunner_Motor_UK_Warehouse_.html

http://www.hobbyking.com/hobbyking/store/__31600__HobbyKing_60A_ESC_4A_UBEC_UK_Warehouse_.html

http://www.hobbyking.com/hobbyking/store/__57166__Tower_Pro_Slowfly_Propeller_9x4_7_Bone_CCW_1pc_UK_Warehouse_.html

If there are any electric gurus out there that can give me the nod I'd appreciate it. On the prop size choice I'm pretty much going on the 4max supplied size for their chapter one specific kit.

Edited By Liam Ryan on 24/07/2016 20:15:51

Edited By Liam Ryan on 24/07/2016 20:16:34

[Biggles' Elder Brother - Moderator]

OK, Chapter One top weight (as I understand it) is around 3.5lb. So target power at 100W/lb will give you 350W. Let's aim at 400W to give us a bit of lee way.

You are looking at a 3s battery - nominal voltage 11.1v. So we cab calcualte an exrimate of the maximum current:

Power=current x voltage

400 = I x 11.1

Max Current = 36A.

So our motor and ESC must be able to handle say 40-50A to allow some headroom.

We want the prop at max throttle to be running at about 10.000rpm. so with 11.1v that would suggest a target kV value for the motor of 10000/11.1 or 900.

So looking at your choices:

The motor: I think this is OK, perhaps a little too beefy - it can handle over 900W! kV is a little high maybe?

The ESC: OK choice. 60A is masses of headroom - you could come down to 50A no problem.

The battery: with a max current of 36A we could estimate the average current at around 60% of that - or say 22A. So, if we want to fly for 10mins, with 20% charge left in the battery when we land, we need 12 x 22/60 Ah of capacity. That's 4.4Ah or 4400mAh. So your battery choice of 3600mAh will not allow that. In fact your flight time with that (with a 20% safety margin) would be around 8 mins. You might feel this is enough - if not you need a bigger battery!

The Prop : wrong type and too small! Get a APC style electric prop. Sze? I'd start at around 10x6 and see how that goes.

Hope this helps

BEB

[john stones 1 - Moderator]

You may have had the advice already Liam ? a wattmeter is an essential bit of kit.

John

[Liam Ryan]

Much obliged BEB,

Does this battery pack fit the bill? I was a bit worried about the 25C but if I'm starting to get my head around it that means it should be able to take a draw of up to 125A which is miles above what we should ever hit

**LINK**

I realize the motor and ESC are a bit over what's needed for the current state of the model but I'm planning on building on the aileron wing once I get a bit competent and possibly re-using the train for a aerobatic trainer as my next build so as long as it's not going to go like a dart I'd prefer to keep the overhead.

The prop really is a head scratcher for me, is it just a case of experience or is there some rule of thumb to go by? When you say wrong type are you referring to the CW/CCW ? Would either of these work?

**LINK**

**LINK**

[Biggles' Elder Brother - Moderator]

Hi,

capacity wise the new battery is fine - the old one was fine too, provided you were happy with 8 min flights -. which is OK. This new one will give you about 11mins. That's quite long. In my experience few beginners can concentrate for that long!. But you could always do two 5 min flights with one battery. One thing to check - does it fit? Its physically quite big - check on the plan that it will fit! Also bear in mind it will push the weight up - and so the model fly faster!

Regarding C ratings - anything 10C up is Ok for this application. Bear in mind higher "c rating" equals higher price, so best to avoid high C batteries unless you need them.

By "the wrong type" I mean its a slo-fly - you don't want that. Something like this would be better. Sadly HK don't seem to have a electric 10x6 that isn't wood in stock in the UK! Or at least I couldn't find one. Wood is a good prop material - but a bit fragile for beginners! The prop you want is a CCW (that's the norm - CW prop are unusual except on muti-rotors) It would be an idea to get a small selection 10x6 11x6, 11x7 maybe?

BTW a lot of your links go to the Global Warehouse at HK? I would advise against ordering from there unless you have no choice. It takes longer and you face possible import duties. Better to set to the UK Warehouse and order from there.

BEB

John is right BTW, a wattmeter really is essential kit! The only way to be sure prop is right is to measure the current it draws at full throttle. Also the only way to ultimateky protect yourself from accidently over-proping and burning the motor/ESC out is again a wattmeter.

BEB

[MattyB]

I wold definitely be buying a bigger charger if I were you - 45W is not a lot of charging power. I always recommend at least a 150W setup even for beginner, as most people either want to charge more or bigger batteries in short order (more power is particularly important if you want to start charging in parallel, which is very handy if you want to shorten the time needed between deciding to fly and loading up fully charged ready to go to the field).

This charger would fit the bill, along with a suitable 250-300W power supply, or just convert a cheap server power supply bought on eBay.

Edited By MattyB on 25/07/2016 01:32:43

[MattyB]

Server power supply conversion information - just search for the model referenced on eBay, they come up regularly at under £20. Half an hours work and you have 575W of über reliable power for a fraction of the price of a commercial PSU of that size, and future proof too - if you get any really big batteries in future you can add another PSU in series to make a 1.1kW, 25V monster!

Edited By MattyB on 25/07/2016 07:35:49

[Piers Bowlan]

The HK Reaktor charger highlighted by MattyB also has the 'storage charge' function, which will extend the life of your LiPos by storing them at about 80% fully charged rather that fully charged.

Buy the best branded charger your budget can manage. The old adage of buy cheap, buy twice seems to apply here. It will also look after your investment in LiPos as well as not burning your house down!

+1 for a Wattmeter.

[Liam Ryan]

Thanks everyone,

I'll grab the props suggested by BEB and order the rest from HK. Thanks for the tip on UK warehouse as well!

Unfortunately factoring in everything including the wattmeter and servos needed to finish construction I'm already hitting the ceiling of my hobby budget for the month so I'll have to go with the all in one charger I linked earlier for now. It will get me going and I can pick up the other charger with another pack or two of batteries next month but I definitely appreciate the advice Matty & Piers.

I've reverted to the original batteries as well, you were spot on about the size and the last thing I want is to increase speed even more when I'm already edging over the line with the motor.

[MattyB]

Posted by Liam Ryan on 25/07/2016 09:26:32:

...Unfortunately factoring in everything including the wattmeter and servos needed to finish construction I'm already hitting the ceiling of my hobby budget for the month so I'll have to go with the all in one charger I linked earlier for now. It will get me going and I can pick up the other charger with another pack or two of batteries next month but I definitely appreciate the advice Matty & Piers.

It's your money, but looking at some recent pics you have posted in your build thread it looks to me like your Chapter One is a fair way off flying yet. For that reason I would just hold off getting a charger at all - the one you have linked to is pretty limited in terms of power and features, and unless you have a model to fly you don't really need the charger asap! Save your £30 for now and put it towards a 200-300W setup in a month - you will have a far better long term charging setup that way, and you'll have saved some money too.

[Biggles' Elder Brother - Moderator]

I think Matty is right here - one of the advantages of building is that the time factor enables you to spread the cost over a couple of months.

BEB

[MattyB]

You could always buy and convert the PSU as a cheap side project this month - £15 inc P&P buys you one of those HP Proliant server PSUs off eBay. That way you will be ready to go once you buy your DC charger next month.

[Liam Ryan]

Not including postage to Ireland Matty but it's a fair point and I'll probably do just that

[David Molineux]

Matty

I've not seen that PSU idea before. I usually use an old 12v leisure battery to power my chargers. I'm definitely getting one of those. Cheers 😁

Dave.

[MattyB]

Posted by David Molineux on 25/07/2016 15:44:06:

Matty

I've not seen that PSU idea before. I usually use an old 12v leisure battery to power my chargers. I'm definitely getting one of those. Cheers 😁

NP Dave. Once you have one you will not look back - they are rock solid, take less than an evening to convert and are designed to run forever. Oh, and they only cost a fraction of an equivalent commercial unit!

Here is mine (a double series linked unit with the DC ground on the second PSU floated as per the TJintech instructions linked above) on it's first test, charging two 6S 5000s at 24V and 20A = 480W. Amazingly at this power level it did not even spin up the fan to full speed! The controller unit on the front is available from Ian Contessa at Coolice; it gives you an on/off button, controls the fan based on the temp of the air exiting the PSU and is recommended if you have an iCharger as they are vulnerable damage if one of the two power supplies in series fails unexpectedly...

 

Edited By MattyB on 25/07/2016 18:16:49

[Liam Ryan]

The batteries, motor and esc arrived today ( with a hefty amount of warning labels might I add! )

I've read through the intro in this forum and I noticed Deans connectors in the photo, these aren't used to solder the motor to the esc though are they? If I were just dealing with normal batteries I'd crimp and solder and wrap some insulating tape around the connections. Can anyone point me towards a nice foolproof step-by-step wiring demo? I'm fine with soldering I've done some electronics before, I just haven't dealt with anything with more bite than 4 AA batteries before so I'd like to get things right.

Coming back to the batteries - with the amount of warnings stuck to these things I'm wondering how to treat a crash when it eventually happens? Is it possible for a pack to be damaged to a dangerous point from the impact or are they a lot more robust than the warnings would lead you to believe? Taken at face value I'd probably watch for smoke or an explosion for a few minutes before going anywhere near the plane.

Thanks again

Edited By Liam Ryan on 28/07/2016 02:35:19

[Dickw]

Deans connectors are common for use between the battery and the ESC.

For connecting the motor to the ESC bullet connectors are the norm, either 3.5mm or 4mm, with heatshrink tubing for insulation. The direction of rotation of the motor can be changed by swapping any two of the 3 motor/ESC wires, so individual bullet connectors allow you to correct a mistake easily.

If you are sure of what you are doing it is possible to just solder the motor/ESC wires together, but I wouldn't reccomend it for most models - it's more for competition types where low resistance and reliability are important.

Dick

Edited By Dickw on 28/07/2016 10:56:45

[Liam Ryan]

Thanks Dick,

I've had good results with Tamiya connectors when doing robotics before, would there be a reason to not use them instead of deans connectors?

I'm still wondering just how volatile the lipos could be in a crash

[Steve Hargreaves - Moderator]

Arrgghhh....... Noooooo not Tamiya connectors....they're horrible things!!! Throw them away & forget you ever set eyes on them....they have no place in electric flight.

XT60s are good, as are EC3 connectors & 3.5mm bullet connectors are very versatile too. It is worth spending some time deciding which connectors to use as you will soon find you need lots of them for all the ESCs, batteries, chargers & wattmeters you seem to accumulate!!

Sorry to be a bit late to he discussion but you have been getting some excellent advice from the other guys. I think you might have overspecced your powertrain slightly though....I've just run up Georges Chapter 1....we have a 35/36 1250kv motor in that with a 9x4 prop on it & this yields around 240 Watts @ 22A. This is plenty in this model. It flies very happily at around half throttle which is just over 80W. The motor is rated to 350W though so a change in prop to a 9x6 will give us a good hike in performance.....useful when I get around to building the aileron wing....

You really don't need more than 250W in a Chapter 1 so experiment with a few props & see what you get. The larger motor might tend to make the model nose heavy so make sure you can move the batteries back enough to balance the model. The standard U/C is fine for a 9" prop but might get a bit low with a 10 or 11" prop....no real matter as you can make the undercarriage a bit longer if you need to.

[MattyB]

I find Tamiya connectors excellent... for wedging open doors! But seriously, that is really all they are good for - their resistance and cycle life are both inferior to any of the other connectors in mainstream use.

Ask a bunch of "sparkle" modellers what their favourite connector is and warfare will often break out, but not one of them would ever mention Tamiya these days. Besides, if you go that route you will literally have to resolved every battery you ever buy as none of them come with Tamiya as std. I personally use Deans and XT60 on my smaller (4S and below and EC5 on the big packs, bit if I were starting again I would ditch the Deans - they are a little harder to solder than XT60s, equally tricky to pull part, but crucially there is less contact area on the Deans blade type connector than a bullet. This makes them slightly higher resistance and sometimes vulnerable to failure, especially the knock off versions; these someomes go slack, risking an intermittent contact type situation.

[MattyB]

Ps - Don't worry too much about lipos in a crash. Yes they can ignite, but it generally has to be a really big impact to do so, and the battery has to be in a fairly full state of charge Just secure them well in Velcro and with a few bits of foam and you will be fine in 99.9% of cases (also remember there are several causes of crashes that are substantially less likely with electrics, most notably the dead stick"arrival".