Hello everyone, I'm new to elect and would like to know how to determine the size elect. I need for my B25 101" weight 30-35 lb. Normally I would use a 26-38cc gas. I am thinking about going elect.

Thank you
Louis

This might be useful reading. http://www.generalhobby.com/arfmfg-s...ane-p-577.html

Since the equivalent of the single gas engine is suggested as 1800-2000W you can perhaps go with two of those.. that would give you well over 100W/lb... so probably plenty for a 30-35lb scale model. What size props are suitable???... that, along with the applied voltage, will determine the correct Kv for the motors. Motor size: if you are looking at 1800-2000W, the 3W/g rule suggests motors weighing 400-600g. [Hacker A50-12L?]

Cheers, Phil

EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC POWERED FLIGHT
http://www.rcuniverse.com/forum/m_7100376/tm.htm

This e-book will help you if you want to broaden your knowledge of electric.

Using a motor selection resource can be helpful too. The Electrifly system works well. I have had good experience with the Rimfire motors.
http://www.electrifly.com/powersyste...tem-index.html

The calculator will let you vary the prop size, flight character, weight and other parameters. Even if you don't want to use Ammo or Rimfire motors you can get specs that can be applied to other brands.


Using the calculator above and assuming this is a twin engine set-up and assuming the largest prop you can use is 16". I used the calculator for the Rimfire motors.

If the assumption is wrong, just make changes in the calculator

Motor Recommendations

[TABLE]
[TR]
[TH][/TH]
[TH]Best Combination
[/TH]
[TH][/TH]
[/TR]
[TR]
[TD="align: right"]Performance
[/TD]
[TD]Sport
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]Motor
[/TD]
[TD]50-65-450 / GPMG4770
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]Gear Ratio
[/TD]
[TD]N/A
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]Gear Drive
[/TD]
[TD]Not Required
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]Propeller
[/TD]
[TD]16x10 in., Electric
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]Battery
[/TD]
[TD]6400 mAh, 22.2v
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]ESC
[/TD]
[TD]SS-80 / GPMM1860
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]ESC Motor Adapter
[/TD]
[TD]Not Required
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]Motor Mount
[/TD]
[TD]Large / GPMP1260
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]Current Draw
[/TD]
[TD]89 amps
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]Approximate Speed
[/TD]
[TD]77 mph
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]Approximate Thrust
[/TD]
[TD]212 oz.
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]Weight of Power System
[/TD]
[TD]55.3 oz.
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]Approximate Flight Time at Full Throttle
[/TD]
[TD]4 minutes
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]Watts per Pound
[/TD]
[TD]123.44
[/TD]
[TD][/TD]
[/TR]
[/TABLE]

This set-up should fly it:

2 X http://www.horizonhobby.com/products...95kv-EFLM4110A
2 X http://www.horizonhobby.com/products...c-CSE010011100
2 X http://www.buddyrc.com/glacier-35c-5300mah-5s1p.html
2 X http://www.buddyrc.com/glacier-35c-5300mah-4s1p.html

This one would provide more power if you wanted to use 3 blade props:

2 X http://www.horizonhobby.com/products...45kv-EFLM4160A
2 X http://www.horizonhobby.com/products...c-CSE010011000
4 X http://www.buddyrc.com/glacier-35c-5300mah-5s1p.html

Add some more $$ in for extension wiring, plugs, etc...
If this is your first electric plane then add about $100-$225 for a decent charger