Re: For those wanting to go electric, my long story
- From: Ken Cashion <kcashion@xxxxxxxxxxx>
- Date: Mon, 13 Mar 2006 11:07:22 -0600
On Mon, 13 Mar 2006 02:32:22 GMT, "desmobob"
<desmobob@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
I've been wanting to increase the performance of my old ElectroStreak and
install a brushless motor. That is, until I started looking for the right
one and became hopelessly lost in a jumble of outrunners and inrunners and
turns and winds and amps and volts and watts and gear boxes and ratios....
I live out in the sticks and don't have access to any knowledgeable electric
flyers or big hobby shops, so I would always end up discouraged. I read a
lot of electric posts on the newsgroup and even saved the more informative
ones but still couldn't seem to really get a handle on the whole electric
thing; enough of a grip that I was able to confidently spend the money
involved to get in the game.
I've flown the ElectroStreak for years (I'm currently flying #2); first, in
stock form, then with Kyosho Magnetic Mayhem truck motors (1900SCR NiCad
packs and Kontronic Sun 4000 ESC) but I really wanted to get her up to date
in the power system department. It's one of those models I take to the
field every once in a while when I get the urge. I always enjoy it.
At the WRAM Show, I decided to put my trust in Sal at Northeast Sailplane
Products and finally break into the brushless thing. I asked him for a
brushless motor appropriate for the ElectroStreak and he handed me a new
RCer Warp4 4-turn brushless motor and a Castle Creations Phoenix 25 ESC. A
3-cell 2100mah 15C LiPo pack and Thunder Power LiPo charger followed.
I came home from the show excited about the new power system. I thought I
had it ready to go until it came time to pick a prop. How do you do it? I
found I needed a watt meter to measure the motor draw with different props
to find one that drew the amount of amperage that the motor was efficient at
but not too much, cooking my ESC and motor or drawing too hard on my
battery. So I ordered a Medusa Power Analyzer. Now what?
Enter MotoCalc. This program allows you to input your airframe, battery,
motor, speed control, and prop choices and gives you a whole bunch of
valuable information on what will happen electrically and otherwise. (free
30-day trial, 39USD to purchase). It's fun to play around and experiment
with different potential power systems or power system components for your
model.
It also gave me enough confidence in my ability to pick proper components
that I decided to upgrade another electric and purchase a new model designed
for electric power. I'm in! I'm in! I flew the 'Streak today with the new
set-up and I was all grins.
I'm a diehard glow junky and IC engine nut, but I also love the convenience
of electric power. My ElectroStreak and Zagi will always have a special
place in my RC heart.
Yes, your story was long and worth every word. I didn't snip
a thing. You have done a service here whether that was your intention
or not.
I am a brushes flier and do not own a LiPo pack or brushless
motor. I haven't worn out what I have but I have decided that it will
it all outlast me so I will most likely get rid of almost all e-things
and start over with current (no pun) technology. And I would have the
same problems in understanding the present stuff as you do/did.
My choices will be the same as yours; learn it the hard way or
ask someone I trust and follow his recommendation...the other one is
get an ARF close to what I want and then learn from trial and few
errors with simple mods. That is what I will do because I want to
know how the new stuff works.
I am a retired NASA electronic engineer so I should be able to
learn the details of the limited range of performances in which I
would be interested.
Now the second thing is the MotoCalc you mentioned. I have
E-Calc and because of the many variations in batteries, props, gears,
motors, etc., there is just no way a guy can live long enough and have
enough money to do all the experimentation in the shop and field. I
believe that E-Calc has easily saved me $400 dollars and almost as
many days of testing. (I have used mine for 10 years.)
I have sat here and gone through the program, printed it out,
and then gone to a contest. If the wind comes up (or goes away), I
might switch props and batteries as recommended by E-Calc...or I might
even change motors, gears, and prop.
I have done this without any prior testing!
I would do what I had figured out would optimize my variables,
rig the model, check the CG, and get me a timer, my score card, and
head out to the flight line for a launch. Sometimes there would be a
minor improvement; sometimes, it would result in an award I would not
have otherwise had gotten.
So ... fellows, ya' wanna' save money? Ya' wanna' save time?
Ya' wanna' "fly" dangerous combinations while sitting at the computer?
Get one of the computer programs and have fun.
Ken
.
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