I'm looking for help with a motor calculator for electric motored aircraft
Anybody there use one of these programs?
I'm looking for a motor solution to electrify a SIG Rascal 40
Weight = 5.5 lbs.
Wing Area = 728 sq.ft.
Designed for a .40 engine ... but I want to go electric ... so I need;
What Electric Motor ... Manufacture and Model
What Motor Controller ... Manufacture, Model/Amps
What Gear System ... Manufacture, Model/Ratio
What Propeller ... Manufacture, Model/Size
I've already gone to MegaMotorsUSA and looked at their solutions ... but if
you've got something better I'd like to know about it ...
Mahalo, Capt. RainDownOn-U Walt Perko
None of the components you've listed will do anything without a
certain crucial component, the battery. The battery is not only your
fuel tank, it's also the determining factor in how much power you will
have available. More cells means more Volts means more power. Power
comes from the product of Volts and Amps. You can use a lower-voltage
battery and draw more Amps, but that makes a lot of heat and your
flight times will be short. It's better to use more cells, spin the
motor faster, and gear it down to use fewer Amps.
Here are a few *ROUGH* equivalents for glow-electric conversions,
assuming you use Sub C cells and prop for a full-throttle current of
about 35-40 Amps. Note that I say rough. These cell counts are only a
starting point, and only work if you adhere to the conditions I
prescribed at the beginning of this paragraph. Often, you can use
fewer cells, and sometimes you need more:
.15 == 8 cells
.25 == 10 cells
.40 == 16 cells
I said you can often use fewer cells. For example, I am powering a
Tower Trainer .40 with 10 cells, a Kyosho Endoplasma brushed car
motor, a 4.6:1 gearbox, and a 12x8 propeller. I would say that the
plane has about the same performance as one with an OS .40LA or .46LA.
It's about the same size, and has the sae flying characteristics as
your Rascal, so you could use a similar 10-cell power system.
Replace that motor and gearbox with an AXi 2820/10, and you've got a
simple, inexpensive, direct-drive brushless system and two additional
minutes of flight time.
I use electrocalc for many calculations.
Your plane suggestion:
14 cells 2400 mAh, motor Astro FAI40 geared 3.1, prop 14x9. 24 Amp current
draw, so a 40 Amp Esc will do fine.
all up plane weight will rise to about 110 Oz, estimated climb angle about
15 degrees, flight duration about 6 minutes, 10 minutes with clever throttle
10-12 cells on a hotter motor with lower gearing will also do, but more Amp
draw is needed then, (40 amps) and duration will suffer, though performance
may be enhanced.
Best advice I could give you is to download MotoCalc for a free 30 day
trial and try out varios combinations.
I flew a similarly sized Kadet Seniorita for a couple of years with a
geared Astro 25 and 16 cells. Fine flyer, plenty of power. Have a
Kadet Sr with Astro 40 and 18 cells about ready to go, and expect
I already had the Astro motors, but if I hadn't I would probably go
with a Mega as you are considering, with gearbox to turn a prop in the
12/8 to 14/6 range at 30-35 A peak draw. Don't substitute the very
similar (same OEM in fact) Jeti Phasor. The Mega rotor is kevlar
wrapped to prevent it from throwing the magnets at high rpm, as you
will encounter when using a gearbox.