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Old May 21, 2010, 01:17 PM
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darook's Avatar
Johannesburg, South Africa
Joined Apr 2006
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Me 110 power setup?

Hi Guys

Busy building a twin me 110 and have a few questions re power setup. I have no idea how heavy but the wingspan will be 1600mm. I guestimate probably 2.5-3.5 pounds maybe?

a.) Do you work on the 100 watts per pound principle?
b.) Batteries - Will I need one 6s or two 3s in parallel?

It seems the twin setups I have found so far use 3S2P. Is this because a 6S battery will burn out a pair 3S motors? Must I keep the output voltage at 11.1V(3S) and ramp up the total mAH to keep the flight time up, to accommodate the 2 motors?

I have attached my sketchup drawings for a an idea of what I am building.
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Old May 21, 2010, 10:51 PM
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Chattanooga, Tennessee, United States
Joined May 2003
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You have a good grasp of it all......yes, 3s is the way to go....far more motors and ESC's are operated on 3s than on 6s (such high voltage requires more specialized components, external BECs etc)...two 175W motors should be fine (say 16-17A on 3s). Determine the prop size which best suits the plane, then hunt up motors with the appropriate Kv (and amp capability) to spin them at 16-17A on 3s (a pair of 25A ESCs would be good). Total amp draw will be 32A-34A so you'll need batteries capable of coping easily with that.
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Old May 22, 2010, 01:31 AM
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darook's Avatar
Johannesburg, South Africa
Joined Apr 2006
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Thanks Dr Kiwi.

I looked at a three blade prop, probably 12x8 or so.... from there I have no clue as to how to match a motor and esc to that.

Guess I will have to troll the forums some more.... unless some one can direct me to tips on how to match motors and props etc.
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Old May 22, 2010, 06:10 PM
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Chattanooga, Tennessee, United States
Joined May 2003
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Whoa, 12x8x3 will require a very large amount of power, if you expect to spin them fast enough to get decent pitch speed!

Here is one way to get 50mph:.. but this needs 1000W total... and the motors weigh 6oz each!

Motor: Dualsky XM3548CA-5; 850rpm/V; 1.87A no-load; 0.032 Ohms.
Battery: Thunder Power TP5200 (G4 ProRace 50C) (50C); 3 cells; 5200mAh @ 3.7V; 0.001 Ohms/cell.
Speed Control: Castle Creations Phoenix 60; 0.0012 Ohms; High rate.
Drive System: Direct; 12x8 3-bladed (Pconst=1.17; Tconst=1) direct drive.
Airframe: Anything you want.

Motor Amps = 46.3
Motor Volts = 10.9
Input (W) = 505.2
Prop RPM = 6859
Thrust (oz) = 77.4
PSpd (mph) = 52.0


If this plane has a 5ft wingspan... is that AUW, or is that 2.5-3.5lb just the airframe.
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Last edited by Dr Kiwi; May 22, 2010 at 06:19 PM.
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Old May 22, 2010, 07:56 PM
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Chattanooga, Tennessee, United States
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I figure that a pair of 70g Suppo A2217K-8T (1100Kv) motors might do well with 9x5x3 GWS HD props...they should draw just under 20A and ~200W. I have not tested the 3-blade on this motor, but 2-blade gets you:

10.7v, 16.75A, 180W, 9840rpm, 46.6mph, 985g, 34.68oz, 5.47g/W

Since, from my testing on other motors, a 3-blade would draw about 20% more... and get you commensurately more thrust.

AUW is, however, an important number to know!
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Old May 23, 2010, 02:32 AM
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Johannesburg, South Africa
Joined Apr 2006
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OK - Guess I have to be careful pulling everything off the 3 view. I was quite keen on a pair of scorpions. Will have to search a bit on ebay to get a decent supplier from Hong Kong area.

something like this......

Model Number S-2215-22
Rotation Speed 940 Kv / RPM/V
No-Load Current 0.5 Amps @ 10 volts
Motor Resistance 0.13 Ohms
Max Continuous Current 16A
Max Continuous Power 180W
Body Dimensions (Diameter x Length) 27.9mm x 27.6mm
Shaft Dimensions (Diameter x Length) 2.95mm x
8.2mm (Front) / 4.8mm (Back)
No. of Stator Arms 12
No. of Magnet Poles 14
Recommend Model Airplane


That seems about right eh?

Doc, thanks for your input of knowledge and time, it really is kind of you.
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Old May 23, 2010, 10:05 AM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
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darook,

There are a few threads already on the Me 110 model, if you want to see what others have done.

Try the following -

Click on Search (towards the top RH side), click on Advanced Search in the drop down, (a new window opens).
Enter Me 110 in the Key Word(s) box.
Set, Search Titles Only in the little box just underneath.
Click on Aircraft - Electric - Airplanes to highlight it, (it's in the Search in Forums box, on the lower RH side, it saves searching every forum here).
Click on Search Now.

You should get 13 threads with Me 110 in their titles, all from the electric forums.
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Old May 23, 2010, 02:44 PM
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Dr Kiwi's Avatar
Chattanooga, Tennessee, United States
Joined May 2003
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Quote:
Originally Posted by darook View Post
OK - Guess I have to be careful pulling everything off the 3 view. I was quite keen on a pair of scorpions. Will have to search a bit on ebay to get a decent supplier from Hong Kong area.

something like this......

Model Number S-2215-22
Rotation Speed 940 Kv / RPM/V
No-Load Current 0.5 Amps @ 10 volts
Motor Resistance 0.13 Ohms
Max Continuous Current 16A
Max Continuous Power 180W
Body Dimensions (Diameter x Length) 27.9mm x 27.6mm
Shaft Dimensions (Diameter x Length) 2.95mm x
8.2mm (Front) / 4.8mm (Back)
No. of Stator Arms 12
No. of Magnet Poles 14
Recommend Model Airplane


That seems about right eh?

Doc, thanks for your input of knowledge and time, it really is kind of you.

Scorpions are good!
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Old Jun 25, 2010, 04:14 PM
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United States, WI, Fond du Lac
Joined Sep 2008
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Quote:
Originally Posted by Dr Kiwi View Post
I figure that a pair of 70g Suppo A2217K-8T (1100Kv) motors might do well with 9x5x3 GWS HD props...they should draw just under 20A and ~200W. I have not tested the 3-blade on this motor, but 2-blade gets you:

10.7v, 16.75A, 180W, 9840rpm, 46.6mph, 985g, 34.68oz, 5.47g/W

Since, from my testing on other motors, a 3-blade would draw about 20% more... and get you commensurately more thrust.

AUW is, however, an important number to know!
I used a similar set up in my P-61
http://www.rcgroups.com/forums/showthread.php?t=1132193

With these motors:http://www.hobbyking.com/hobbyking/s...idProduct=5687

I got combined thrust with the GWS 9x5x3 of 52 oz for a total draw of only 24A from a single 2200mAh 3s battery. Two blade 10x6 boosts thrust to over 60 oz with a draw of 26-27A and a higher pitch speed to boot. I'm going to use the same setup in my Dinah. http://www.rcgroups.com/forums/showthread.php?t=1240702 I've been happy with this setup and I thought the motors were good quality. The shaft sticks out the back if you use the included prop adapter but thats a minor issue.

You might want a little more power for your larger 110 but if it comes in under three pounds, this is an efficient setup for a twin that can run on a single 3S. Under 13 oz. total including ESCs and wiring.

Multi engine electrics can get heavy really fast if you get carried away with wanting lots of power.
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