CorsairJock
Posts: 1939
Joined: 4/14/2002
From: Parchment,
MI, USA
Status: offline
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quote:
ORIGINAL: nchrome
I personally don't realy know all that there is about electrics. Except in my opion without being a math wiss there is no way to tell what motor is rite for what plane its all a big secret to most electric flyers. I know that if I build a forty powered plane then I can get a forty or what ever engine for that plane  . But if I want to go electric I have to whip out the slide rule and the paper and start figuring out the weight,airfoil,prop size, wing load, the amount of time I want to fly  . I have enough work in the plane alone. I surly don't want to have to find out that I need a collage degree . 
You are right, it is more challenging determining correct setup for electrics (battery, prop, motor), because of the way manufacturers label/ number the motors. There isn't an electric motor out there that says on the label 'use this motor inplace of brand X .75 2 stroke'.
Here is a web-site tho, that should help out a lot. All you do is 'plug in' a possible combo (motor, prop, battery) and it will provide a pretty good idea of what to expect as far as performance (thrust, duration, prop speed), If the figures don't look good for whatever project you are planning, try another setup.
http://brantuas.com/ezcalc/dma1.asp
quote:
ORIGINAL: nchrome
I presenly have a C-47 electric (brush motors)and rite now I have an extra $60.00 in just speed controls Then the lipos to get a ten min flight will cost about $240.00(thats 2P-3S packs 2400 mil amp) and for that ten min flight I will need two of these. Plus a battery saver cost ? too keep from drawing too much juice from them now we need a lipo charger  .
You don't say anything about size/ weight. But it seems you are paying too much for Li-Pos, and not getting good results. I have two 3S (11.4 volt) 4400mAH packs in series in my Corsair. That's 22.8 volts, 4400 mAH, from which I get two 7 minute flights per charge (or one 12 minute one). Total cost for the packs about 1 year ago was $165, I have over 100 flights on them. I expect to use them this coming summer with same results. 3rd year, I'll have to wait and see. And I have flown this plane up to 6 times in same day, altho 2 times is the norm.
Tower has some 3S 2200 packs for under $75 each, and there's a guy selling 3S 1800 packs here at RCU Marketplace for $45. Admittedly, these will cost more than the nitro fuel needed for a year or 2 for a plane the same size/ weight. But don't forget to add glow plugs into the fuel power cost.
Bottom line (again): a carefully selected electric motor and speed control can be cheaper and lighter than fuel power system needed for same plane. LiPo battery packs cost more, but not as much more as some seem to think. How much do warbird pilots spend on fuel (and glow plugs) a year? And this isn't about 'which type of motor is better for a warbird', this is more about setting the record straight and dispelling myths. But if I was into jets and/ or multi-engine warbirds, electrics would definately be my 1st choice.
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Avatar: Electric Powered, Highly Modified Hangar 9 Corsair
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All Forums >> RC Airplanes >> RC Warbirds and Warplanes >> RE: 2-Cycle or 4-Cycle for a 1/7-1/8 Warbird? Which is the preferred type? 
RE: 2-Cycle or 4-Cycle for a 1/7-1/8 Warbird? Which is... - 
. i have mostly 2 strokes and one four stroke that was given to me, and i prefer the two stroker, cheaper, faster, lighter, so what if it uses a wee bit more gas, and sounds like a swarm of bees... 10 to 12 bucks a gallon doesn't kill me. i mean am i right? or am i the only penny pincher here??? maybe its the military job, i knew i shouldve gone to college first to make the big bucks!!! 
well that was just my two pesos, even if you dont ask me... 
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