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Old Feb 05, 2007, 02:30 PM
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College Park, Maryland, United States
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CASA F5B Contest (old VA F5B contest) April 28-28 and Sept 29-30

The spring CASA F5B contest will be held Sat. and Sun., April 28 & 29th. (weather permitting). The club board has approved our request. It would have been nice to have it later in May, but the calendar was busy. In the last of April, the weather can be either very good, or wet and cold.

We have also set up September 29 & 30 for the Fall contest. Mark your calendars.

This year will mark the first time that we will allow the use of LiPo's in competitive airframes. There will be two classes: F5B open class with either up to 16 round cells or up to 4s LiPo, and F5F with either up to 10 round cells or up to 3s LiPo. We will not be weighting or measuring ships, but encourage flyers to fly the correct size plane in the correct class.

This contest emphasizes fun and learning to fly the course at optimal speed. Beginners and/or novices are more than welcome to bring their hotliners and learn to fly the course with freely available advice from the more experienced flyers.

Detailed discription of directions and flying field location available from either Jay or myself.

Don
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Old Feb 05, 2007, 05:17 PM
turn, turn, turn.
Athol, Massachusetts
Joined Oct 2005
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That's good news for me that this year you will be allowing lipos.
I was determined to wait for news of your event without any input on my part. My apologies again, for the manner in which I presented my views on lipos for last years event.
Looks like I've run out of excuses not to attend.
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Old Feb 10, 2007, 08:47 AM
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Reston, VA
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What are the rules for LiPos and a123s? Figure I can go to 36 V with the same weight.
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Old Feb 10, 2007, 09:29 AM
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Greeley, Colorado, USA
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Quote:
Originally Posted by HavingFun2002
What are the rules for LiPos and a123s? Figure I can go to 36 V with the same weight.
Except that it's not only a weight limit, but also a voltage limit. Lipos are likely to be limited to 4S packs.

Lenny
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Old Feb 12, 2007, 10:10 AM
corrupted - 17x18 or more
eye_rc_soar's Avatar
College Park, Maryland, United States
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Quote:
Originally Posted by HavingFun2002
What are the rules for LiPos and a123s? Figure I can go to 36 V with the same weight.
For the CASA contest (see first post):

Quote:
This year will mark the first time that we will allow the use of LiPo's in competitive airframes. There will be two classes: F5B open class with either up to 16 round cells or up to 4s LiPo, and F5F with either up to 10 round cells or up to 3s LiPo. We will not be weighting or measuring ships, but encourage flyers to fly the correct size plane in the correct class.
When I wrote this I was not thinking of a123's when I said "round cell." I was still entrenched with the NiMh and NiCad mentality. As CD, I would classify the a123's (Li Ion, 3.3 nominal V) as in the LiPo class and allow only up to 4s configurations and would not consider them "round cells."

Don
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Old Feb 12, 2007, 10:35 AM
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United States, VA, Leesburg
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Quote:
Originally Posted by eye_rc_soar
For the CASA contest (see first post):



When I wrote this I was not thinking of a123's when I said "round cell." I was still entrenched with the NiMh and NiCad mentality. As CD, I would classify the a123's (Li Ion, 3.3 nominal V) as in the LiPo class and allow only up to 4s configurations and would not consider them "round cells."

Don
So David,

Wire up sixteen A123 cells as 4S4P for some real power!
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Old Feb 12, 2007, 11:07 AM
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Reston, VA
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Quote:
Originally Posted by eye_rc_soar
For the CASA contest (see first post):



When I wrote this I was not thinking of a123's when I said "round cell." I was still entrenched with the NiMh and NiCad mentality. As CD, I would classify the a123's (Li Ion, 3.3 nominal V) as in the LiPo class and allow only up to 4s configurations and would not consider them "round cells."

Don
Here is where things get confusing. So, the a123 put out less per cell, thus if I'm limited to 4 I'll go with standard LiPos. However, the a123 are less expensive, and are safer...you can't overcharge them.

This time next here we'll all be on them, might as well start now. However, I will play by the rules and bring a $400 pack. :-)
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Old Feb 12, 2007, 11:11 AM
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Reston, VA
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Quote:
Originally Posted by down_shift
So David,

Wire up sixteen A123 cells as 4S4P for some real power!
Good point. However, I think that will be less power more duration than the standard LiPo cells. I need all the power I can get.

I've been running a 6S a123 configuration in my F5B ship. 22V and only $50 bucks for the cells (out of a Dewalt pack). Can't beat that.

I'm telling you guys, might was well move this direction now, we'll be there soon.
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Old Feb 12, 2007, 11:13 AM
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Reston, VA
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Quote:
Originally Posted by eye_rc_soar
For the CASA contest (see first post):



When I wrote this I was not thinking of a123's when I said "round cell." I was still entrenched with the NiMh and NiCad mentality. As CD, I would classify the a123's (Li Ion, 3.3 nominal V) as in the LiPo class and allow only up to 4s configurations and would not consider them "round cells."

Don
"either up to 10 round cells or.."

Too late. Now I get to show up with a 36V ship. You got to love how quickly this stuff changes.
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Old Feb 12, 2007, 11:19 AM
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Aren't 16 round cells quite a bit more voltage than 4s lipos? And certainly more voltage than 4 a123s. 4s lipo really equates with 12-13 round cells.

1.2 nominal x 16 = 19.2v
3.7 nominal x 5 = 18.5
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Old Feb 12, 2007, 02:05 PM
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Greeley, Colorado, USA
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Quote:
Originally Posted by thunder1
Aren't 16 round cells quite a bit more voltage than 4s lipos? And certainly more voltage than 4 a123s. 4s lipo really equates with 12-13 round cells.

1.2 nominal x 16 = 19.2v
3.7 nominal x 5 = 18.5
No, not in practice because it's the voltage under load that really matters. A good 4S lipo has the edge (right now, at least).

Lenny
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Old Feb 12, 2007, 02:44 PM
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Reston, VA
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Here are the costs:

4 cell 2500mah LiPoly @ 14.8V, is $121.15,

4 cell 2300mah, A123 @ 13.2V, is $91.95.
6 cell 2300mah, A123 @ 19.8V, sells for $122.95.
8 cell 2300mah, A123 @ 24.6V, sells for $153.95.
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Old Feb 12, 2007, 02:46 PM
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Reston, VA
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Quote:
Originally Posted by Lenny970
No, not in practice because it's the voltage under load that really matters. A good 4S lipo has the edge (right now, at least).

Lenny
Yep. Lenny is right. However, the costs and tech will change a lot in the next few months.
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Old Feb 12, 2007, 03:53 PM
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Wow, you guys must be using some really good lipos. Or maybe just bad NiCDs. What is the voltage under load per cell for the NiCds/NiMHs you're using? Isn't pushing them to below about .9v/cell destruction? I'll admit I don't have any of the latest generation lipos, all mine are 15C right now. They will put out about 3.5v/cell at their rated capacity.

On a weight by weight comparison, though, lipos always have an edge.
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Old Feb 12, 2007, 04:20 PM
turn, turn, turn.
Athol, Massachusetts
Joined Oct 2005
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Quote:
Originally Posted by thunder1
Wow, you guys must be using some really good lipos. Or maybe just bad NiCDs. What is the voltage under load per cell for the NiCds/NiMHs you're using? Isn't pushing them to below about .9v/cell destruction? I'll admit I don't have any of the latest generation lipos, all mine are 15C right now. They will put out about 3.5v/cell at their rated capacity.

On a weight by weight comparison, though, lipos always have an edge.
I just bench tested a 5s TP Extreme 2070.
I got 48 amps and 650 watts.
That's 2.7 volts per cell.
I'm not surprised.
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