Giant scale electric power with A123's (Full Version)

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marc 540 -> Giant scale electric power with A123's (3/30/2008 3:58:54 AM)

Is it possible to run A123's instead of li-po's to power giant scale outrunner engine's? I'm thinking about converting my 50cc gasser to electric but li-po's are very $$$!!


Thank's Marc 540[8D]



everydayflyer -> RE: Giant scale electric power with A123's (3/30/2008 4:17:36 PM)

Of course you can. Years ago some rather large aircraft were converted to electric using motors from cordless power tools and Nicd batteries. These motor were far heavier and less efficient than modern brush-less motor and the Nicds were also much heavier.

During the past few years there has been a LiPo mania epidemic and everyone seems to this that LiPolys are the only viable power source for electric flight.

I flew many .40 size aircraft with 4 and 5 cell A123 2300 mAh batteries. One is a Sig Fazer which had an OF .46FX with tuned pipe and ran a 12X4 prop. It now has an AXI 2826-12 5S A123 and APC 13X6.5E prop. It in fact weighs almost 12 oz. less and has better power then it did when glow powered. AUW is 4 1/2 pounds and it has just over 600 watts of power.

A good site to do a little research is

http://homepage.mac.com/kmyersefo/M1-outrunners.htm

Here is aan interesting Thread on RC Groups

http://www.rcgroups.com/forums/showthread.php?t=722914

Charles



Walt Thyng -> RE: Giant scale electric power with A123's (4/4/2008 3:03:41 PM)

How does a 1/4 scale Reno racer biplane with a MagaMax and 12 A123s on a 16/12 prop sound. Is that giant scale enough> Or a Nosen Citabria on a geared Astro 60 with 32 NiMhs? Cobra is 19lbs rtf, cit is 17lbs rtf. Cobra has been radared at 85mph (scale would be about 66 mph).


sorry, I don't know how to post pics to this forum yet.
Walt



dirtybird -> RE: Giant scale electric power with A123's (4/6/2008 1:21:32 AM)

Here is a couple of pics of my installation in a Nitroplanes 80" Extra. I just took two Dewalt packs and removed the case and hung them on the firewall. The motor is a Hacker 6016 and turns a 20x10 prop at 5700 on the batteries. The longest flight I have had so far is 4 minutes after which I charged each pack 1 AH. At that rate I should get 8 minutes and still have power to land. The Extra landing gear need beefing up to withstand the extra 2lb of the electric conversion.
The airplane weighs 17lb resulting in 37 oz/sq ft wing loading. With 15 lb max thrust it seems to fly OK but its not good for 3D. I would rather fly like an airplane than flit around like a butterfly anyway.



dick Hanson -> RE: Giant scale electric power with A123's (4/6/2008 11:05:12 PM)

Here is my latest approach:
I have a couple of "60" size motors One is the EFlite -the other a similiar sized one from Extreme Flite .
I started setting up a little YAK from Seagull -65 " thing - anyway -I put in the EFite 60 and new 60 EFlite controller
and figgered on 7 cells - pushing the limit on VOLTAGE for the ESC
After sme cogitating and discusion with a friend who is running 16 A123 in series (yes series) on a geared Nue -- I decided to ge another ESC which would allow more voltage
NOT more amps -mor voltage --so I got a Cyclon 80 HV - good for 40 volts (these are on blow out at Horizon for 101 bucks a steal as list was 300 bucks
Now I am going to use th little YAK as a mule to try 8cells on th e 60 -thats almost 29volts starting voltage --which will smoke a 24 v ESC
I will have to fiddle to get best prop size for this 23 oz pack but I thinkit will all work out .
I am shooting for --40 amps with whatever the prop prooves out to be -
I am looking for lower amps more volts -cooler running-andbased on others reults it looks feasable
charging is easy - I have both 8 and 4 volt chargers and I will build two 4 cell packs connected in series with the EFight Y.



dirtybird -> RE: Giant scale electric power with A123's (4/7/2008 1:50:34 AM)

If you look closely at the pictures you will note I have the plastic inner holders from the Dewalt packs still on the packs. This allows me to check each cell voltage. After about ten recharges I have not had to rebalance. I have not yet run them more than about 50% discharge.
My charger is nothing more than a full wave rectifier connected to a variac and powered by a 1K Pep Boys generator. For a filter I have an automobile noise filter and a 4700uf capacitor I got from Radio Shack. It reduces the ripple to about 2V P-P. I can charge up to 25 Amps with this. I just watch the voltage and quit at 37 volts. Since it usually only takes 10 minutes its no problem.
I got the batteries from Ebay for $170, the motor from Viper hobbies for $75 (show special) and the ESC from Hyperion for $185. Thats less than the ZDZ 40 the airplane is designed for.
The Hyperian ESC is good for 12 Lipolys so I could go up to 14s2p if I need more power and get longer flight times if I wanted to. I have plenty for me as it is.



dirtybird -> RE: Giant scale electric power with A123's (5/12/2008 7:12:54 PM)

One interesting fact to me is the 60 size electric motor is supposed to be the same as a a .60 glow motor.
My Hacker 6016 draws about 60 amps on 30 V @ 5500RPM with a 20x13 prop. Thats about 1800W or less than 3 HP. A good glow .60 will give you more HP than that easily. However, a good .60 glow swinging a 11x8 prop at 15000RPM is sure not going to pull that 17lb airplane like the electric does.



dick Hanson -> RE: Giant scale electric power with A123's (5/13/2008 1:58:04 AM)

you can not compare the glow 60 to an electric.
why? the electric has max torque at zero and then torque goes down
the glow has no torque at zero rpm and builds in a curve to max out at about 12000.
a 15000 rpm 60 is doing that best at flight speeds of way over 100mph
we spent 30 years with these little glo thingys
You CAN get a setup which very roughly approximates the two on a sport model.



everydayflyer -> RE: Giant scale electric power with A123's (5/13/2008 2:02:58 AM)

I find that around 450 watts on a 12X8 or 13X6.5 prop provides performance similar to but better than a good .45-.50 glow with a 12X4 prop. Larger dia. / higher pitch props are more efficient. Many glow flyers learned this when 4 cycles started to appear years ago.

Some practical data here

http://homepage.mac.com/kmyersefo/M1-outrunners.htm#RETURNDIA


Charles



dick Hanson -> RE: Giant scale electric power with A123's (5/13/2008 3:20:29 AM)

It all depends on what type model you are flying
basically a "square pitch / dia is one of the best - IF the motor will pull it . example: a 14x14 APC on a YS1.2 four stroke on a 9 lb aerobatic (pattern) model
the 3Dstuf is very low speed so a 14x6 -is better and so forth
a common setup for current sport models is a 10"pitchor less -



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