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Nov 16, 2017, 11:52 PM
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Correct.
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Jul 11, 2018, 03:02 PM
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kurupt17's Avatar
Very interesting
Aug 14, 2018, 07:27 PM
Fly Crash Fix Fly
As a newb I find all this stuff to be a bit of a black art. Thanks ChrisF for explaining it in simple terms, this is exactly what I've been looking for.
Feb 22, 2019, 02:51 PM
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Hermani's Avatar

Choosing the right motor


Recently I bought a RC ARF kit plane and I am in doubt about choosing the right motor.

The model is quite light and is supposed to have an overall weight (AUW) of 500 grams. Now I need to choose a motor.

I would prefer to go light on this model, as I want this to be a trainer and not a performance model. This is the first non-foam aircraft I'll be flying (and I haven't that much experience as well ). I have an Emax 2805 motor (26 gram) which ought to be suited for models with an AUW of 200-300 grams. It appeals to me because I intend to keep the model light. Otherwise I could use a heavier 2212 980kV motor but that motor would be heavier, require a heavier ESC and a larger (and heavier) battery as well - that all will make the model heavier.

Should I give the 2805 a shot or would this be a waste of time and should I opt for a heavier motor?
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Aug 03, 2019, 04:43 PM
Registered User
looking for a little help. Returning to the hobby from a long lay off from the nitro days and my first foray into electric flight.

I am recommissioning a old Hanger 9 Arista 40. Previously powered by a YS-56. I am recovering the plane and have modified it with a removable hatch for battery access.

Plane Specs:

Advertised weight 6.2 pounds
Wing Span 56 inches
Wing Area 565 inches
Wing Loading 25oz

Chosen Motor Rim Fire 45
KV 800
Constant Watts 1000
Burst 1850

Speed Control Talon 90

I have played with several of the calculators but what I end up doesn't quit make sense to me.

Motor specs state 5s or 6s but everything ends up overheating the speed control in the calculators. the only thing that gives me decent specs is a 3s.

So what I'm looking for is what battery to run and what prop for around 7 to 8 min flight times.

Sorry I'm such a D.A. in this area but I'm thankful for any help.
Aug 04, 2019, 04:50 AM
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Fourdan's Avatar
Hi
Just a first suggestion :
Kv 800 rpm/V .. OK for 3S LiPo
With APC E 14x10 you will draw ~50A (WOT @ 11.1V)
With 3S LiPo 5000 mAh and an average current of 40A you will get around 5/40 = 0.125 hour = 7.5 minutes 5000
(Zippy 3S , 5000mAh = 420 grams)
ESC around 80A max

If you want 4S or 5S or 6S you have to lower the motor Kv

You can play with freeware Scorpion Calc
http://www.rcgroups.com/forums/showthread.php?t=736782
Select the close motor SII 3026-710 and edit the Kv to 800 rpm/V
Then select Source 3S LiPo and scroll the prop upto the APC 14x10E(#232)
Louis
Aug 05, 2019, 02:20 PM
Registered User
Thank you Fourtan for your assistance, One more question. in the battery area of the calculator i understand the "S" is for the number of cells but it is followed by a another area that is denoted with a "P". What info are the looking for in this area?

Again thanks for the help.
Aug 05, 2019, 03:24 PM
Registered User
Fourdan's Avatar
Quote:
Originally Posted by mobileraptor
Thank you Fourtan for your assistance, One more question. in the battery area of the calculator i understand the "S" is for the number of cells but it is followed by a another area that is denoted with a "P". What info are the looking for in this area?

Again thanks for the help.
Hi
Scorpion Calc (SC) is considering/managing only the number of cells (or voltage) for the source
xP is a parameter regarding the cells in parallel (or the capacity in mAh)
The capacity is acting only on the flight duration (not considered in Scorpion Calc)

The main results of SC are
* rpm
* static thrust (airspeed = 0)
* pitch speed
* current
* Power In (W) and power out(W), efficiency
tools are :"propellers" frame
Louis


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