Top Flight Elder 20 Electric
03-17-2003, 02:33 AM
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Top Flight Elder 20 Electric
If I want to use a 10 inch prop. and the airplane has a wing area of 500 Square inches 52 inch wing span Flat Bottom Wing. and it is around 2.75 pounds with no radio or motor installed.
the airplane is made for a .25 size 2 stroke.
What electric motor would be a good pick?
speed controler?
and batery pack?
I need help... I know nothing about electric.
I don't want to run to big of a prop... is a 10 inch a good size?
thanks... any ideas would be great.
the airplane is made for a .25 size 2 stroke.
What electric motor would be a good pick?
speed controler?
and batery pack?
I need help... I know nothing about electric.
I don't want to run to big of a prop... is a 10 inch a good size?
thanks... any ideas would be great.
03-17-2003, 01:48 PM
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Top Flight Elder 20 Electric
of course you can easily make it fly electric, but with such a tiny little prop and being so heavy,.. it's going to take a lot of power. You're looking at 5.25~5.5 lbs probably by the time you add 12~14 cells with a geared motor and small servos and such(figure 2 to 2.5 lbs for power system depending on cellcount, assuming sub-C cells). To get adequate performance, you're going to need about 300 watts minimum,.. better at 400~500 though, so current is gonna be a bit high for a putt-around plane like that due to the low cellcount. If, however, you'd go to a larger prop, a 13X8,.. 14X7, 14X10, etc,... you could keep the cellcount down to 10 or so, and draw less current (less input power, but good, or better, thrust due to the large prop). You gain so much efficiency with a larger prop that you can use less input power to get the same thrust. Pitch speed suffers just a wee bit, but the elder is a putt around plane anyway, so pitch speed is almost irrelevant.
When getting into electrics, you really have to change your whole mindset regarding propping
My funtana, for instance, was setup with a 20X8 prop and drew 66 amps peak (about 1/3 of that average) off a 30 cell pack. That's 2100 watts fresh off the charger. thrust was roughly 18 lbs (11.6 lb plane) with a pitch speed in the low 50's. I re-geared to use a larger prop (22X12) and now I'm down to 53 amps , about 1800 watts (1/7 less power going in), but thrust is up over 20 lbs, and pitch speed is actually a bit higher,..so,.. from 20X8 to 22X12 (just 2 inches more prop) I'm using 1/7 less power from the batteries (longer flights) yet gaining about 10% in thrust, and about 5% in pitch speed. Gary's rule of thumb for electrics,... Gear HIGH and swing a BIG prop
When getting into electrics, you really have to change your whole mindset regarding propping
My funtana, for instance, was setup with a 20X8 prop and drew 66 amps peak (about 1/3 of that average) off a 30 cell pack. That's 2100 watts fresh off the charger. thrust was roughly 18 lbs (11.6 lb plane) with a pitch speed in the low 50's. I re-geared to use a larger prop (22X12) and now I'm down to 53 amps , about 1800 watts (1/7 less power going in), but thrust is up over 20 lbs, and pitch speed is actually a bit higher,..so,.. from 20X8 to 22X12 (just 2 inches more prop) I'm using 1/7 less power from the batteries (longer flights) yet gaining about 10% in thrust, and about 5% in pitch speed. Gary's rule of thumb for electrics,... Gear HIGH and swing a BIG prop
