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Old Feb 07, 2009, 05:19 PM
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Christchurch, New Zealand
Joined Jun 2006
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Well, I don't think you need either 6s or 5000mAh.

Here's my setup:

Hyperion 4020-14
Hyperion Titan 80 Opto
Hyperion 5S 3700 pack
APC 13x8E prop, exactly the predicted 67A static, which is about 1300W.

Now, that motor is 574 KV. So, you should be fine with a 580 KV motor on 5s 3700, or maybe up to about 4300 if you want a bit more duration.

If this is your first big electric, I'm not surprised it's up front cost is more than glow. But, don't count the battery as part of the cost of the plane... that's its fuel for a few years. And then think about what it's going to do to the cost of your second big electric... all of a sudden that's quite a bit cheaper, 'cause you already have the battery.
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Old Feb 07, 2009, 07:00 PM
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Northern California
Joined Feb 2009
8 Posts
Thanks Andrew. How long does your battery config last you?

And for Mike, what is your A123 config and what is the duration?

Mark
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Old Feb 07, 2009, 07:13 PM
"NAVY CHIEFS"
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NAF Atsugi, Japan
Joined Jul 2005
628 Posts
Quote:
Originally Posted by mlr2000
Thanks Andrew. How long does your battery config last you?

And for Mike, what is your A123 config and what is the duration?

Mark
Mark,
I'm running 5 cell 2 parrell. I flight for about 12 min scale flight. When I just go nuts I get about 9 mins of high speed fun.

Mike
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Old Feb 07, 2009, 07:42 PM
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USA, AZ, Mesa
Joined Jul 2002
7,209 Posts
Mike,

Now that I have a bunch of A123 cells I'm thinking about dragging my Cessna out and finishing it sometime in the next year or three. I have a Scorpion 4020-12 in mine. Where did you mount your cells? I've heard a lot of people put them inside the cowl to help with balance. I may go with 6S2P.

Joe
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Old Feb 07, 2009, 10:19 PM
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Christchurch, New Zealand
Joined Jun 2006
6,794 Posts
Quote:
Originally Posted by mlr2000
Thanks Andrew. How long does your battery config last you?

And for Mike, what is your A123 config and what is the duration?

Mark
I haven't flown it for a while, I have to rebuild the left wing yet. But my Lancair, which has an even hotter 4020 power system, gets about 9 minutes if I don't do too many high-speed passes (which, I have to admit, are a lot of fun with that plane... it's fast!). So the Cessna ought to get a bit more.

Speaking of the Lancair... there's a plane that is much, much harder to fly than the Cessna. Stabilised approaches only, or else.
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Old Feb 07, 2009, 11:24 PM
"NAVY CHIEFS"
rc_man1's Avatar
NAF Atsugi, Japan
Joined Jul 2005
628 Posts
Quote:
Originally Posted by turbojoe
Mike,

Now that I have a bunch of A123 cells I'm thinking about dragging my Cessna out and finishing it sometime in the next year or three. I have a Scorpion 4020-12 in mine. Where did you mount your cells? I've heard a lot of people put them inside the cowl to help with balance. I may go with 6S2P.

Joe
Joe,
I made a hole thru the firewall and made a slide tray to mount the motor and the A123's Look below. I have no extra weight in the plane.She came out on the money.

Mike
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Old Feb 09, 2009, 01:03 AM
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Northern California
Joined Feb 2009
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Looks like A123's are the only way to go. Seems very few retail options for these and all the threads from various sites suggest building your own from an ebay DeWalt 36v pack. I like a challenge but this whole build is gona tire me out from plane all the way to battery. Meantime, before I can build a battery, is there a way I can power up and test (on the ground) my new turnigy motor and 80A ESC before the 30 day return policy expires with a test power source, perhaps 12v RV battery or 2 in series for voltage? Or the two e-flite LiPo 3200mah packs I mentioned before (not full throttle of course to avoid under amp)?

And Mike, that is a terrific job you did on the firewall to make space for your batteries and balancing your CG. Routers sure come in handy from time to time for things like this.
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Old Feb 09, 2009, 02:39 AM
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Christchurch, New Zealand
Joined Jun 2006
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The 3200s will be fine if you just fit a 12x8 prop to reduce the load; test the current, if it's still too much, come down to 11x7.
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Old Feb 09, 2009, 03:56 AM
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madhun1's Avatar
Sunshine Coast
Joined Jun 2006
1,495 Posts
Quote:
Originally Posted by mlr2000
Looks like A123's are the only way to go. Seems very few retail options for these and all the threads from various sites suggest building your own from an ebay DeWalt 36v pack. I like a challenge but this whole build is gona tire me out from plane all the way to battery. Meantime, before I can build a battery, is there a way I can power up and test (on the ground) my new turnigy motor and 80A ESC before the 30 day return policy expires with a test power source, perhaps 12v RV battery or 2 in series for voltage? Or the two e-flite LiPo 3200mah packs I mentioned before (not full throttle of course to avoid under amp)?

And Mike, that is a terrific job you did on the firewall to make space for your batteries and balancing your CG. Routers sure come in handy from time to time for things like this.
If you had a vice you could mount the motor, esc, speedy, pack and rx to a plank of ply and secure it in the vice. Ensure the prop won't foul anything, stand well clear and operate with the TX.

Would be a good idea to whack in a data logger if you had one to do some testing whilst you are there.

HC are pretty good replacing any broken items.
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Old Feb 09, 2009, 11:25 AM
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Northern California
Joined Feb 2009
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Andrew, if I wanted to test full capacity of the setup with 13x8 prop under full load (on ply in a vice as good suggestion here) could I use two 12 RV batteries in series (24v) with 5 meters of 18 guage wire (to limit current)? I seen an interesting YouTube video on use of two 12v batteries in series (not parallel) to re-charge your A123's >>>
6s2p A123 Direct charge method video#1 (7 min 33 sec)
. And good to here HC is good on returns if problems. This is my first order with HC and somewhat concerned as shipping is EXPENSIVE overseas back and forth.

Mark
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Last edited by mlr2000; Feb 09, 2009 at 04:45 PM.
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Old Feb 09, 2009, 04:37 PM
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Christchurch, New Zealand
Joined Jun 2006
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You know, those 3200s will not be unhappy with one short run at full power. Keep it less than, say, 15 seconds at full power and they'll be fine. Just don't let them get hot.
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Old Feb 09, 2009, 06:53 PM
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Northern California
Joined Feb 2009
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Well for a test of the motor and ESC on the ground I guess that won't hurt. Just don't want to destroy anything. Been doing a lot of reading on the A123'on the web today. Seems pretty straight forward. Mike's configuration looks like it will do the trick. The 12v car battery charge method for the A123s in the YouTube video seems hopefull but not sure how he handles "balance" charging or maybe it does not matter with A123s since you cannot overcharge them.
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Last edited by mlr2000; Feb 09, 2009 at 06:59 PM.
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Old Feb 24, 2009, 01:13 PM
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San Jose, CA
Joined Mar 2000
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What motor from hobbyking (aka hobbycity) would be ideal for this plane? I need a recommendation and a fast one please. Thanks

Tony
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Old Feb 24, 2009, 03:56 PM
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NAF Atsugi, Japan
Joined Jul 2005
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Quote:
Originally Posted by rcdude
What motor from hobbyking (aka hobbycity) would be ideal for this plane? I need a recommendation and a fast one please. Thanks

Tony
Tony,
I used the 50-55B 600kv trinity motor on mine and it's over powered. Flights really fast and will go stright vertical..

Mike
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Old Feb 27, 2009, 08:15 AM
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Connecticut, USA
Joined Oct 2008
144 Posts
For those interested it looks like nitroplanes.com has got the 50 size plane in stock again. I just got this link in my email.


http://www.nitroplanes.com/cmskylaarf50.html

Looks like $119+shipping until 2-28-09
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