TLyttle

Interesting stuff. This is where I get called a dinosaur. This is where the derisive laughter starts. This is where I get called a tightwad. Go for it, guys, I have been insulted by real experts.

I am still running brushed motors and NiMH (even NiCads!) as a power source. I have no intention of converting to brushless, or LiPos, simply because I can't afford it. My question is simple:

I am using a pair of Speed 400s (brushed) on a project that calls up that power. The motors will be in parallel. Can my 30amp speed control handle that without letting out the smoke?

Any sane answer will keep me from going back to diesels...

AEAJR

Assuming you have a reasonable prop on the motors, each speed 400 should draw between 10 and 13 amps, so a 30 amp ESC should work.

It would be best to put a wattmeter on the set-up to confirm, but I think you will be fine.

TLyttle

Thanks, AEAJR, I'll do that then...

Rescue2slc

Great info on here I am am new to wattflyer and am extremely impressed. Still confused though. I just picked up a CMP P40 .50 and I am semi clueless on the power system I should use. This is what I have come up with so far.already have to Eflght ESC, batteries, and the ar7000 so trying to make good use of them. Any insight or suggestions would be greatly appreciated.

1. Turnigy 50-55 580Kv / 1580w or SK Series 42-60 500Kv / 1475W
2. 60 AMP EFlight ESC
3. (2) 3s 1800mah run in series. ( may buy the 2200 mah zippys) >?>?
5. AR7000

I am using retracts with it as well ...do I need a external BEC?
total of 6 servos. Maybe 7 if I add the tail wheel retract. 2 hitec 425's (retracts)and 4 322HD standard servos. Also want a scale 3 blade prop and spinner.

Thanks again for all the great info.

-Joe

AEAJR

Tell us why you selected this set-up and we can better tell you if it will meet objectives.

With no link to the planes information, no link to the motor's information, and no stated performance goal, all I can say is that it will consume electricity and churn the air.

slipstick

I guess you're talking about the old .50 size CMP Warhawk P40 which only weighs in at about 6lb.

Those motors are WAY too big. You only need about 700W, maximum 1000W. Even at that you'll be lucky to get run times of more than about 3 minutes with 1800mAh batteries. Something like 4000mAh will be more like it.

And unless your ESC has a switch mode BEC you will definitely need an external BEC.

Steve

Rescue2slc

Thanks Steve...I think the finished weight should come in around 6lbs. I take a look at some other motor options... Looking at the turnigy stuff. On a budget so the wife doesnt kill me and so far all I have heard about them is good... Ill keep you posted. Thanks again for the info

Joe

Mooney_Driver

I have read through most of this sticky trying to find information hopefully in the form of a chart that equates nitro engine size to electric size. I know that the 400 size electric is about equal to .049 nitro but others I am not so sure about.

I am looking for electric equivalents to the Cox .010 and also the Cox .020 engine but most of what I see starts with the 400 class electric. I assume park flyer motors must be in a different category as I do not easily locate them when looking through sites such as Hobby Lobby or Tower.

Thank you.

AEAJR

There are all kinds of such charts. None of them agree because this is the wrong approach to take to size an electric motor. If you read the thread you know that the proper way to size an electric motor to your plane is watts/pound.

As you know, not all .010 motors are the same nor area the .020s. Not try to create a chart that equates every .10 and .20 to every electric and you would need a major spreadsheet to use the tool.

But watts/pound works as the best starting point.

If you did not read that in this thread, then read this book on electric power:

Everything you wanted to know about electric power.
http://www.wattflyer.com/forums/showthread.php?t=31071


If you just want to buy a motor that is this MFG says is comparable to a .10 then buy this one:
http://www.horizonhobby.com/Products...odID=EFLM4010A

The claim this one is about comparable to a .25
http://www.horizonhobby.com/Products...odID=EFLM4025A

This is claimed to be similar to a .46
http://www.horizonhobby.com/Products...odID=EFLM4046A


If that is what you want, then you have what you need.

http://www.wattflyer.com/forums/showthread.php?t=31071

camazar

I just go by the Spec on the New Parts of buy & steer towards the Max output when looking into Li-po Batteries or ask @ you LHS if the person is inclined enough to know about what he Sells.?

FlyWheel

AEAJR - Do you have a PDF of this? I mean just this, no other postings. Like you did with Everything You Wanted To Know About Electric Powered Flight?

AEAJR

No I don't, but the content that I added here is in the e-book, for the most part.

rc modler

I am not sure if this is where this belongs or not, If not, administrator move it to where it belongs.

My question is How can I use the battery that came with my radio and the one that I use with my ESC. I have been a gas person for many years. I started when I was in Italy back in 1967 using the Kraft radios and supertigre and rosi endings and the ever so nice cox 049/051 them were the days. I just got tired of carrying all the stuff that goes with gas.

I have not been into electric that long hence my question above. I just need to know how I can hook both batteries up. Can it even be done.

Thanks in advance.

slipstick

I guess you're talking about in the plane and you mean the 4.8V battery that came with the radio vs the whatever it is battery you intend to connect to whatever ESC you're using. Yes ?

For real details you'll need to tell us what ESC and batteries you mean.

Most relatively small ESCs have a "BEC" function which means you don't need to use the other separate battery at all. The main battery powers the Rx and servos as well as the motor through the throttle channel on the receiver.

On bigger planes/ESCs that's not necessarily so. If the ESC doesn't have a BEC then you can just plug your normal receiver battery in the BATT slot on the receiver and connect the ESC to the throttle slot.

There are also a few other variations so let us know EXACTLY what ESC and battery it is you're talking about.

Steve

rc modler

Slipstick

Thank you for your reply. I think I know where I am at now all I had to do was look at my receiver. I have quite a few planes but I am mainly interested in using the dual batteries in some foamies as a test with weight. I am using the 4.8 that comes with the Spectrum DX7. Now if i use an ESC with a BEC will I have voltage conflict to the receiver?? I think so but I am not sure. Like I said I am just testing different things out I just dont want to cause damage.

GO

kyleservicetech

Let us know which ESC you are using. Most ESC's have a built in BEC (Battery Elimination Circuit) that can power your receiver and servos for the smaller models. But, once you get past the "Foamie" sized models, you've got to be a little careful with that built in BEC.

For the larger models, check out those switching types of BEC's such as the Castle Creations 10 Amp BEC, or the Common Sense BEC. I've used both for years with complete success.

Now, Castle Creations, along with several other ESC mfg's have come up with an ESC with a built in uBEC (switching power supply BEC) that will do the job. The CC units have the "ICE" designation.

Note that you can NOT use both an internal BEC, and a separate receiver battery at the same time. If you use a separate receiver battery, you must disconnect the red wire of the ESC servo connector. Just lift the tab, pull the red wire out, and cover it with a piece of tape or shrink tubing.

Hope this helps.

rc modler

Kyleservicetech

Yes that really helps a lot. Thank You.

George

70sflyer

I am not sure of my battery choice and would like some feed back.I am building a 60 hanger 9 Corsair.Im thinking close to 9 lbs when completed.Motor is AXI 4130/20,305 KV.controller is Phoenix 80 ESC.Prop is 15/8.For battery I am thinking a 5000MAH,6S,30C.Is that in the ball park?Any help would be appreciated.Thanks Dean

2.4ghz

all kinds of information on this forum i like this

kyleservicetech

Check out www.motocalc.com, free for 30 days, then $39. This will get you into the ballpark.

Question, do you all ready have the motor? AXI motor specs show that their motors winding resistance is 0.099 ohms, rather high for the power expected out of the motor. At 40 Amps, that's 150 watts lost directly in the motor windings itself.

Other options, check out the various Hacker A50 series motors. I've got both their A50-12S and A50-16S motors, for three years now. The A50-16S motor is very close in weight and KV to the AXI motor, but will far outperform it, per motocalc. The winding resistance of the A50-16S motor is 0.026 ohms, 1/4 that of the AXI. This motor is actually a fraction of an ounce lighter than the AXI.

My A50-16S motor is in a Showtime 50 with 6S2P A123 cells (about the same as a 5S1P 4000 Mah Lipo) with a 16X12 APC-E prop. The motor turns this prop at about 5900 RPM, and pulls the 8 pound Showtime with authority.

Also got two A50-12S motors with same 6S2P A123 cells with a 14X10 APC-E prop. This motor turns the prop at 7950 RPM, and pulls two other 8 pound models with authority. This motor is pulling about 60 Amps on the ground.

Hope that helps.

2.4ghz

I am thinking you have it about right except maybe prop, I would go with the 15/10 or bigger maybe in the 16 or 18 range, check this out
bhttp://www.modelmotors.cz/index.php?page=61&product=4130&serie=20&line=GOLD and your battery is good. you are in the ball park there. That would be a great set up for that plane

70sflyer

Yes ,i have the AXI but it looks like I should put it on Ebay and but a Hacker.Thanks for your help.Dean

ashutosh

This is my first post and hence I have restrictions to PM and link posts. Kindly bear with me.

----------
Hi Chris,

In the first post, under section "Wing Loading and Stall Speed" the link to calculate "wing loading" is not working.

"try this calculator coloradogliders ........"

Kindly correct it or add a newer link.

Thanks,
----------

Softfx

So much information to remember ...

GFH

I'm no dummy but it seems to me everyone has two different names for everything and one uses apples for measurement and the other oranges.

I've been a gas guy and decided electric for the next

SO I'm confused .............what do I need.

The model is 10 pounds a Jerry Bates Interstate Cadet (similar to a J3). Recommended power is a 60-90 2 stroke or 90-120 4 stroke or 23cc Gas.

What do I put on it for power? I might also use it to tow gliders up bt what is suggested with and without the towing option?

Cheers and thanks

G