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Power Systems Talk about motors, ESC speed controllers, gear drives, propellers, power system simulators and all power system related topics

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Old 03-30-2011, 06:32 PM   #1
sgillmore
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Default SIG Somethin' Extra Conversion

I'm planning to convert SIG Somethin' Extra to electric and hoping to use a setup that I already own. The plane should come about around 4.5 - 5 lbs AUW and is a general sport flyer. Hovering is not a goal. I'm pretty flexible on flight time as long as it's over 5 min.

Here's the planned setup:
Rimfire .46
CC Phoenix 80
Koolflight Systems UBEC
A123, 2300mAh 6S1P

I have a watt meter and expect to test many props before I'm finished, but I'm thinking that an APC 13x6.5E would be a good starting point.

I'd appreciate any constructive comments or recommendations on this setup.

Thanks!
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Old 03-30-2011, 06:36 PM   #2
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Hi
Pleased to meet you
Very good info here
http://www.rcgroups.com/forums/showthread.php?t=544821
Hope this is of help
Take care
Yours Hank

"When wild the head-wind beat,Thy sovereign Will commanding, Bring them who dare to fly, To a safe landing."
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Old 03-30-2011, 06:58 PM   #3
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Originally Posted by kenchiroalpha View Post
Hi
Pleased to meet you
Very good info here
http://www.rcgroups.com/forums/showthread.php?t=544821
Hope this is of help
Take care
Yours Hank
Thanks for the link. BTW, great avatar--R. Lee Ermey is "The Man".
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Old 03-30-2011, 07:12 PM   #4
kenchiroalpha
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Originally Posted by sgillmore View Post
Thanks for the link. BTW, great avatar--R. Lee Ermey is "The Man".

Hi
Your most welcome
I agree 110%
Take care
Yours Hank

"When wild the head-wind beat,Thy sovereign Will commanding, Bring them who dare to fly, To a safe landing."
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Old 03-31-2011, 12:27 AM   #5
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Well, a Rimfire .46 is 268g..... and the suggested ESC on 6s is 60A.

The first rule of thumb suggests watts = cubic inches x 2000... thus 920W max.

The second rule of thumb (3W/g) suggests 800W max.

Motocalc suggests that using a 13x6.5 (max recommended for 6s is 11x5) you'll draw
>63A and 1360W... welcome to the world of immersion heaters.

Motor: Great Planes Rimfire 42-60-800 (#4725); 800rpm/V; 4.6A no-load; 0.017 Ohms.
Battery: Thunder Power TP4400 (G4 ProPower 45C) (45C); 6 cells; 4400mAh @ 3.7V; 0.002 Ohms/cell.
Speed Control: Castle Creations Phoenix 80; 0.001 Ohms; High rate.
Drive System: Direct; 13x6.5 (Pconst=1.17; Tconst=1) direct drive.
Airframe: Anything you want.
Motor Amps = 63.7
Motor Volts = 21.4
Input (W) = 1361.5
Prop RPM = 9570
Thrust (oz) = 121.7
PSpd (mph) = 58.9
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Old 04-01-2011, 06:29 AM   #6
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Originally Posted by Dr Kiwi View Post
Well, a Rimfire .46 is 268g..... and the suggested ESC on 6s is 60A.

The first rule of thumb suggests watts = cubic inches x 2000... thus 920W max.

The second rule of thumb (3W/g) suggests 800W max.

Motocalc suggests that using a 13x6.5 (max recommended for 6s is 11x5) you'll draw
>63A and 1360W... welcome to the world of immersion heaters.

Motor: Great Planes Rimfire 42-60-800 (#4725); 800rpm/V; 4.6A no-load; 0.017 Ohms.
Battery: Thunder Power TP4400 (G4 ProPower 45C) (45C); 6 cells; 4400mAh @ 3.7V; 0.002 Ohms/cell.
Speed Control: Castle Creations Phoenix 80; 0.001 Ohms; High rate.
Drive System: Direct; 13x6.5 (Pconst=1.17; Tconst=1) direct drive.
Airframe: Anything you want.
Motor Amps = 63.7
Motor Volts = 21.4
Input (W) = 1361.5
Prop RPM = 9570
Thrust (oz) = 121.7
PSpd (mph) = 58.9
I'm using A123 cells, not LiPOs. They're lower voltage and I'm not getting anywhere 1300 watts on MotoCalc with the 13x6.5.
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Old 04-01-2011, 06:45 AM   #7
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If your using A123 cells, then a 13" prop is probably safe for a first test but it will likely still be pushing that motor. Be prepared to prop down.

Those are not the most efficient motors so I would stay on the lower end of the power range Dr kiwi suggested above and use throttle management.

I think I need a signature.
Larry
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Old 04-01-2011, 03:37 PM   #8
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Originally Posted by Larry3215 View Post
If your using A123 cells, then a 13" prop is probably safe for a first test but it will likely still be pushing that motor. Be prepared to prop down.

Those are not the most efficient motors so I would stay on the lower end of the power range Dr kiwi suggested above and use throttle management.
Yeah, I'll do some static testing of course and try to keep an eye on things. I don't fly a plane like this very hard. Just cruise it around with some basic aerobatics thrown in. I'll only be full throttle for short vertical up-lines. I suspect a 12x6 or a 12x8 might be the ticket.

I had a Somethin' Extra converted to electric a couple years ago with an AXI 4120 and CC Phoenix 60. I was flying it on a 4S1P 4000mAh Li-PO with a APC 13x6.5E. It performed really well. It was a beautiful, kit-built SE that I wish I'd have held on to. I sold it at a fun fly and the guy crashed it that night.

I have this setup hanging on the wall and have an opportunity to acquire another SE so I thought I'd give it a try.

I fly with a Hitec Aurora and have a full sensor station on order that will allow me track RPM, motor & ESC temps and current while in flight. I ordered it for another, much larger project (B.USA 1/4-scale FOKKER D.VIII). However, I might slip the sensor station in the Somethin' Extra for some test flights to get everything worked out.

Thanks.
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