Boeing

My Feedback: (145)

Am new to the electric flight arena. In setting up the power system for an electric powered aircraft, how can I be sure I have the appropriate combination of battery, ESC, motor and propeller.

Do not want to end up killing the battery, ESC, or motor by using the wrong combination.

What sort of malfunction is indicated when after a flight, you find that the battery is swollen?


Thanks for all and any information you electric guys can provide.

Cheers,
Boeing

tIANci

Boeing ... welcome to the Dark Side! How to go about it? Like this:

Motors - problem with motors is that there is no standard rating unlike GP engines, so you can use a motorcalc software or the recommended set up or info from others in forums
ESC - based on cell count and amp draw, anything more than 3 cell needs separate power supply for the RX but the Turnigy Plush 60A and 80A does not need the external power suply, its built in to handle the RX. If you are properly propped you want the following power to weight ratio as a baseline guide:

Easy flying: 75W/lb - 125W/lb
Sport flying: 125W/lb - 150W/lb
3D flying: 150W/lb - 200W/lb

Batt - cell count to suit the motor and prop, capacity depends on amp draw. Keep withing the 80% rule, means if the batt can handle 100A discharge use it in a system that draws 80A max. Its a healthy guide.

Prop - use the size that matches the motor and number of cells used, usually we use 8"-10" pitch props for flying unless its 3D then for smaller planes as low as 5.5" or 6". Diameter is larger than what you get on GP engines because generally we run on lower RPMs. My 40 sized planes are running 13"-15" props if clearance permits.

To make it easy for you, let us know what plane you are looking into and then we can all suggest something. Bloated batts? Possibly its been over discharge, in terms of amps or voltage (dropped below maybe 2.9V per cell).

Boeing

My Feedback: (145)

Thanks for the reply tIANci!!

Provides alot of good information that I can digest.

The aircraft I'm looking at is actually two: the Multiplex Fun Jet and the Multiplex Easy Star. For the Easy Star I am considering replacing the stock brushed power setup with a brushless system.

Again, thanks of the info,

jooNorway

This is a small challenge, you have to find a motor which gives you the oomph you want running a 5" or 6" propeller. (I guess) Due to small space

cyclops2

Swollen batteries are like Hand Grenades with the firing pin lost.

We know it will blow up. Not when. Always dig a 1foot deep hole. Carefully lay it in the hole& cover it with plenty of dirt. Make SURE there is NOTHING burnable near it.

There is NO safe way to handle a swollen battery.
NO one knows when it may burst into flame.

Rich

cyclops2

On a happier note.

There are free web sites that will give you very good motor / esc / & prop calculations. It will stop bad guessing & swollen batteries.

Rich

tIANci

Boeing FunJet and Easy Star? Okay ... here we go:

Easy Star ... use a 28mm x 40mm motor from HobbyCity. Something in the 2,000KV-2,200KV range with 3S packs. Prop it with a 5x5 or 6x4. Get a 40A ESC once and for all. Turnigy ones work great. You should be pulling about 25A only. Now you have an issue here, the plane was designed for NiMH but you will probably fly with 25C 3S 2,200 packs. Now a single pack will be ever so slightly tail heavy. If you can, carry some ballast, about 2-3 oz it will make her fly nicely. That should get the CG about right. For me she flies nicer in that manner.

FunJet ... how fast do you want to go? If you are keeping to the same packs then use the following, 28mm x 40mm motor of not more than 3,000 KV ... use a 40A ESC and turn either a 5x5 or 4.75x4.75. You will be drawing about 30+A and that is a nippy set up, not awesomely fast but very nippy. The Mega 16/15/3 is nice and sweet motor to use. I flown my FunJets on 3S, 4S and 6S. My next one, No. 6 I think, will be a simple light set up using 3S 1,500 packs and the Mega 16/15/3 turning a 5x5 prop. She is lovely to fly when light. The fast hot set ups are really lousy in the way it handles due to the higher wing loading. They go fast but I do not enjoy how they handle. With a light or average set up, cruise her around and feel how smooth she is. For a simple set up you can afford to use those Tower Pro 9g servos, it will be sufficient. For fast set ups I use the HS65s.

When building the FunJet, I dock off the turtle deck just behind of the intake. Why? So I can fit the motor in and then have access to double side tape the ESC in place, I don not like it flopping around. Also, try to tape together the connectors from the ESC to the motor, in case of a hard landing, they will not detach. Please ensure its properly insulated, you do not want to tape the connectors then fry your motor when it shorts.

tIANci

I must say that I have seen so so so many swollen batts here, but I have yet to see them blow up. I am not saying that they never will but just not seen it blow despite being repeatedly used by pilots. They swell because gasses are released and its trapped. Some branded batts have chemicals that do its best to scrub the excess gasses. For me I am not keen to use bloated batts because the performance is no longer good. I dispose of mine in landfills. Mind you these things can combust. Try this advice:

[link=http://thunderpowerrc.com/PDF/DISPOSAL-OF-LIPO-BATTERIES.pdf]Disposing Lipos Safely[/link]

Also, for safe charging its good to place the batt in a earthen pot or a big porcelain mug. In case anything goes wrong it will contain the flames. It does not explode but burns like firework/gun powder. You can use those lipo-safe bags too, its cheap from Hobby City. Better safe than sorry! Seen chargers go bad while it was being charged in a moving car ... was funny how my pal described how he had to brake hard and chuck the batt out! Another burnt his hobby room ... I doubt the missus was impressed at how he redecorated the room.

Rockfish88

Hello,

I am setting up a kit plane, StevensAero Soarstik, with a GWS 350c motor, Electricfly C-12 Micro ESC, four Hitec HS-55 Servos, and a AR6110e receiver from Spektrum. I use a Spektrum Dx6i transmitter. In the guide to setting up the plane, it tells me to center the servos using your transmitter. How does one do that? The Dx6i manual is pretty much silent on this question. Any ideas? Do I basically have to have the whole system running to set the servos?

Thanks!

tIANci

Rockfish ... That would mean ensure that the servos are set at neutral. I am not familiar with your DX7 but its basically a JR and with my 9X when you set up, ensure that the FLAPS are all set at ZERO. So go to the flap function and ensure the FLAP positions are all at 0%. Then try to get the horns in a 90* setting to the servo housing or level it as necessary. This may happen by moving the servo horn on the servo output shaft or if its slightly out then use the SUB TRIM, not the trims by the gimbals.

Boeing

My Feedback: (145)

Set up my Easy Star much like you suggested and I have a "new" glider!!!

This machine now leaps into the air and is a much better flying aircraft.

Thanks for your information.

heavy metal thunder

I had a cheap 2200 15c 4s battery actually catch fire in flight in one of my EP gliders after about a 30 second burst of power at launch. Fried the ESC and crashed the glider. The battery was ejected at impact, made a flying streak in the sky, and left a 1' burn spot on the grass. The glider has repaired and is flying well. I still use canopy that got burned and show it to the newer electric flyers what can happen when a battery catches fire.

faster the better

hello all

I am new setting up funjets and at present will be buying the multiplex funjet, I have been recommended the hi max 4400 kv inrunner with 60 a esc running 3s 30c cells is thios going to be fast ??

can anybody out there give me some advise as i want to go really fast

tIANci

Faster man ... 4,400KV? You will probably burn the motor or ESC or kill the batt if you want to stick to 3S. If its a 28mm motor 4,400KV is heck of a lot, unless you drop your prop to a 3". I tested out a 28mm x 40mm motor of 3,600KV with a 4.7x4.25 prop on 3S, she was already overheating.

How fast do you want to go? On 3S she is not that fast, on 4S to 6S she is pretty fast but you are talking about a lot of watts for not that much more speed with also the 'pig wallowing in the mud' handling because of the higher wing loading. I have tried her in 3S, 4S and 6S configuration. I favour the 3S with a light set up, a personal preference.

The FJ is nice to fly but its a draggy airframe, there are other planes out there where you can get really great speed with less watts put in.