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Old Oct 21, 2012, 07:18 PM
That's a funny word
NE Ohio
Joined Apr 2003
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I just realised I have a new wattmeter too. Never used it yet. I'll definately get some readings with it. I'm also not afraid to use my 30 amp esc for a few second test. I can also hook my best battery up to it if it proves to be a weak battery. I do know the IR is about the same as it was before because I just tested it today before flying.
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Old Oct 21, 2012, 08:22 PM
If I build it, it will fly
United States, NY, East Rochester
Joined Jan 2012
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If the motor/prop is suppose to draw over 30a you may not get an accurate read, even for a few sec, but the fresh battery will be nice to compare vs your first on the watt meter... Speaking of watt meter, luck bum! HeHe

~psguardian
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Old Oct 21, 2012, 08:35 PM
That's a funny word
NE Ohio
Joined Apr 2003
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I got 10 volts x 25 amps and about 245 watts with my spent cold pack.
I get 11.8 volts x 29 amps and about 348 watts with the same full warm pack.

This is a nice combo with 11x5.5 prop on the Sensei with all stock equipment. Now my question remains to be why the current is much lower than webcalc shows. My only speculation is that it is because the motor is "undersized"
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Last edited by gulio; Oct 23, 2012 at 06:29 PM.
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Old Nov 25, 2012, 12:38 PM
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United States, CO, Grand Junction
Joined Oct 2009
229 Posts
Need motor help

building and older kit that calls for and includes GWS 280 size brushed motors, i need to know what a reasonable substitute brushless motor is.. around the same size with as much or more power
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Old Nov 25, 2012, 10:22 PM
UMs & parkflyers... for now.
davidterrell80's Avatar
United States, VA, Herndon
Joined Apr 2012
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Quote:
Originally Posted by jquackjr View Post
building and older kit that calls for and includes GWS 280 size brushed motors
It'd be easier to answer knowing which kit (the type and size of model) and the style of flying (scale, 3D) you intend to perform. Then, one can pick a motor/esc/propeller combination for the job, rather than just replace the original.

That said, I assume you mean the motor/gearbox combination?

http://www.aeromicro.com/catalog/280...bs__804154.htm is stats on the EPS-100C for 2S and 3S
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Old Nov 26, 2012, 07:31 AM
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United States, CO, Grand Junction
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need 280 motor replacement for EAM c130

that is fair enough,
i appreciate the help.

http://www.rcgroups.com/forums/showt...t=eam+c130here is a link to the plane i am building.

I am concerned about the brushed motors burning out quickly, and feel brushless would offer more power and longer flights. i prefer not to gear the motors as there is not really room in the nacelles for that. I have not started building, just trying to get the plans together and decide if 4 Bl motors and 4 esc are going to work....
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Last edited by jquackjr; Nov 26, 2012 at 07:32 AM. Reason: forgot link
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Old Nov 26, 2012, 06:20 PM
UMs & parkflyers... for now.
davidterrell80's Avatar
United States, VA, Herndon
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I'm doing a little research... meanwhile, this is a place you might consider reading for future knowledge.
http://www.wattflyer.com/forums/showthread.php?t=31368
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Old Nov 26, 2012, 07:04 PM
UMs & parkflyers... for now.
davidterrell80's Avatar
United States, VA, Herndon
Joined Apr 2012
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Here is my thinking.

The plane's thread says the flying weight came out 2lb 9oz (2.7 lbs). For scale flying, call it 80 W/lb or a total of 216 W and rounding up to 220 for ease of math... divided by 4 motors... means 55 W per motor. If you use 2S lipos (7.2 V) you get 7.6 A per engine and round to 8 A.

So you're looking for a motor/esc/prop that will deliver 55 W at 2S running about 8 A.

Something like the E-Flight Park 250 (almost perfect at 55 W max) or E-Flite Park 300 (if you want power reserves at 88W max) or an equivalent.

Also, a buddy has recently finished an Avro Lancaster of almost the same weight as your plane. The build thread is HERE.

He powered two engines and let the other two props be freewheeling.

His stats were
Scratch Built from 6mm and 8mm EPP
Wingspan 1.5m /60", AUW 1200g /42oz with 2x 3s 1500mAh
Motors 2x Emax 2812 1500kv
Props GWS 7x6
ESC's 2x 30amp
Servos HXT 9g
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Old Nov 26, 2012, 11:23 PM
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United States, CO, Grand Junction
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hmmm 2 engines not four...

I am very intrigued by that idea.. i have been looking at the kit and it may allow 2 motors sightly larger/more powerful in the nacelles with minor modification and then i could eliminate the weight of the 2 motors and 2 ESc and wiring, simplify the electronics..... an interesting idea indeed....

the increased power would also allow me to use 3 bladed props...maybe
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Old Nov 27, 2012, 12:52 AM
wood is good
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United States, CA, Marina Del Rey
Joined Jun 2012
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Good thinking outside the box.
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Old Dec 14, 2012, 06:45 AM
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Saudi Arabia, Makkah Province, Jeddah
Joined Mar 2009
130 Posts
Hello friends... wow wow wow ,, very very very very nice and helpful topic really appreciate it NoFlyZone thanks so much and much ...

I want to know the suitable motor and propeller of my 38~42 size Electric KATANA plane, its parameters are :

AUW: 76.8oz
Wing span : 58.9"
Wing loading : 503.5 sq.in

and if i want it for a Fast Sport Aerobatics, i will get these data below.

of course i took the gear ration 1.00 ..
is it good for this plane ??
plane's link :
http://www.nitroplanes.com/cmp-ep-katana-sr.html

thank you very much

Best regards
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Old Dec 14, 2012, 08:44 AM
UMs & parkflyers... for now.
davidterrell80's Avatar
United States, VA, Herndon
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Quote:
Originally Posted by Nobel0 View Post
I want to know the suitable motor and propeller of my 38~42 size Electric KATANA plane ...
If you are purchasing that exact plane, note that it comes with the motor and esc already installed (emphasis added):
Quote:
Features
•Motor Size:4250~710Kv Brushless Outrunner (Included and pre-installed)
•Servos:5 Standard Size Servos (Included and pre-installed)
•Prop Size:13 x 4 (Included and pre-installed) Optional 13x4-13x7 prop can be used
•Speed Control: 50A ESC with built in BEC (Included and pre-installed)
•4.1lbs all up weight minus the battery pack
•4.7lbs RTF (with a Sky Lipo 4s 3000mah 40c Lipo pack)
I ran the numbers through my spreadsheet...

It looks like a 13x6 prop would be the best for that motor and ESC. That combination should give you 145 Watts per pound and about 65 MPH top speed, while topping out at 47 Watts on the ESC. The 13x4 provided will only deliver 60 mph, 120 W/lb, at 41 A... slightly longer flight times and less performance.

I'll attach a zipped copy of the spreadsheet saved with the figures I used for the Katana.
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Last edited by davidterrell80; Dec 14, 2012 at 09:32 AM. Reason: Added the 13x4 data
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Old Dec 14, 2012, 02:35 PM
Registered User
Saudi Arabia, Makkah Province, Jeddah
Joined Mar 2009
130 Posts
Quote:
Originally Posted by davidterrell80 View Post
If you are purchasing that exact plane, note that it comes with the motor and esc already installed (emphasis added):


I ran the numbers through my spreadsheet...

It looks like a 13x6 prop would be the best for that motor and ESC. That combination should give you 145 Watts per pound and about 65 MPH top speed, while topping out at 47 Watts on the ESC. The 13x4 provided will only deliver 60 mph, 120 W/lb, at 41 A... slightly longer flight times and less performance.

I'll attach a zipped copy of the spreadsheet saved with the figures I used for the Katana.
Hello again , thank you very very much for your interest and covidence ...

yes you are all right sir , but when i received it, its all electronics are missing and they told me we r apologies for that but we didnt have these elecs .. instead of that they will give me a $100 i dont have another option ..

so because of that i confused about the suitable motor for fast aerobatics.
i want motor from Hobby king and found :

http://www.hobbyking.com/hobbyking/s...50kv_785w.html

in this motor HK says DATA : 13x10 - 14.8v - 740W - 50A - 2.8kg

is it good for fast sport aerobatic sir ??

i am really confused and i dont know how to get it right, i tried and the results is below.

thanks again sir.
Best Regards
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Last edited by Nobel0; Dec 14, 2012 at 03:31 PM.
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Old Dec 14, 2012, 04:41 PM
UMs & parkflyers... for now.
davidterrell80's Avatar
United States, VA, Herndon
Joined Apr 2012
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That motor and the combination you mention would work very well in that aircraft, with exception of the ESC, which needs a greater capacity than the 50 A drawn by the motor.
-- 13x10 prop
-- 14.8v (4S) battery (I recommend a battery capacity from 3000-4500 mAh for 7-9 minutes of flight)
-- 60 A ESC

Here is a good link to help you complete your education about electric flight. It is where I learned...

http://www.wattflyer.com/forums/showthread.php?t=31368
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Old Dec 15, 2012, 12:59 AM
Registered User
Saudi Arabia, Makkah Province, Jeddah
Joined Mar 2009
130 Posts
Quote:
Originally Posted by davidterrell80 View Post
That motor and the combination you mention would work very well in that aircraft, with exception of the ESC, which needs a greater capacity than the 50 A drawn by the motor.
-- 13x10 prop
-- 14.8v (4S) battery (I recommend a battery capacity from 3000-4500 mAh for 7-9 minutes of flight)
-- 60 A ESC

Here is a good link to help you complete your education about electric flight. It is where I learned...

http://www.wattflyer.com/forums/showthread.php?t=31368
Thank you very very very much i appreciate it man .. thanks so much ...

ok i will take 60A ESC and propeller 13*10 which is :

http://www.hobbyking.com/hobbyking/s...ler_13x10.html

and battery :

http://www.hobbyking.com/hobbyking/s...Lipo_Pack.html

,,,,---------------------------------,,,,

thank you very much for the link ...

Thanks again sir...

Best Regards
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